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Apollo 15

Day 11: Worden's EVA Day

Corrected Transcript and Commentary Copyright © 2000 by W. David Woods and Frank O'Brien. All rights reserved.
Last updated 2018-12-31

[This section primarily covers the eleventh day of the mission, August 5, 1971. Apollo 15's CSM (Command Service Module), Endeavour, has left the vicinity of the Moon and has begun essentially falling to Earth. The last burn performed by the crew, the Trans-Earth Injection burn, placed them on a path that would have the spacecraft pass over Earth's far side at an altitude of about 35 kilometres, had the planet been devoid of atmosphere. Of course, the Earth does have an extensive envelope of gas which the spacecraft will intercept, losing its momentum through friction and heat. By that time, Endeavour will be travelling at nearly 11 kilometres per second under the pull of Earth's gravity. But now the Moon's gravity is dominant; the spacecraft is only coasting at just over 1 kilometre per second and is slowing as it continues rising away from the Moon.]

[The primary objective of the day is for Al Worden to perform an EVA (Extra-Vehicular Activity) out through the main hatch and along the side of the Service Module to the SIM (Scientific Instrument Module) bay. There he will retrieve film magazines from the Panoramic and Mapping Cameras and take an opportunity to visually inspect the bay. Throughout their time in lunar orbit, the SIM bay has experienced a few problems and since it will be destroyed along with the Service Module when it re-enters the atmosphere, engineers are keen to gather as much information as they can to aid troubleshooting. The eye of a test pilot is a welcome opportunity to see if any mechanical manifestations of the symptoms exist.]

Public Affairs Officer - "This is Apollo Control. The astronauts appear to be sleeping soundly at this time, this based on the biomedical data we have on our Command Module Pilot Al Worden. And we have about 5 and a quarter hours remaining in this sleep period. The spacecraft is in the Passive Thermal Control mode, rotating at the rate of about 3 revolutions per hour to maintain the proper thermal equilibrium, and has, at the present time, two 24 foot [7 metre] booms extended from the Service Module, one boom holding the Mass Spectrometer experiment, the other the Gamma-ray Spectrometer. Just before we said goodnight to the crew at the scheduled time in the Flight Plan of 228 hours, 50 minutes, they reported that the indicator in the spacecraft showed that the Mapping Camera had not retracted on command. After checking this, primarily with the thermal engineers to determine that there would be no problem as far as the film that's held in the camera's magazine, we elected to leave the camera deployed - it's on some rails that extend out from the SIM bay - and work with it tomorrow. It presents no serious problem. The concern initially was that perhaps, without retracting the camera and closing the doors over the camera, that the film in the cassette, which is now exposed, would get too warm. However a check with the thermal people in the back room indicated that the film should experience no thermal problems. The temperature should remain well within acceptable limits, even with the camera and the magazine extended. And the camera was left in the position that it is in, and one of the things that will be attempted tomorrow is to determine if perhaps the doors, which close over the camera once it is retracted, are possibly jammed against it. Also one thought was that perhaps before we began the Passive Thermal Control rotation of the spacecraft, that the area of the SIM bay where the camera was located may have become quite cold, causing the problem to occur, and perhaps causing something to freeze up and stop the camera from retracting. So the present configuration of the spacecraft is with the two booms deployed 24 feet, the Mapping Camera deployed, and [the spacecraft] rotating about its longitudinal axis at the rate of 3 revolutions per hour. At the present time Apollo 15 is 16,668 nautical miles [30,869 km] from the Moon, and the spacecraft velocity is 3,910 feet per second [1,192 m/s]. At 230 hours, 34 minutes; this is Apollo Control, Houston."
[Despite PAO Announcer's words, the rest period was due to begin at 228 hours exactly. Delays in finishing yesterday's activities delayed its commencement by 50 minutes.]
Public Affairs Officer - "This is Apollo Control at 232 hours, 27 minutes Ground Elapsed Time. 3 hours, 17 minutes remaining until crew awake time. The crew of Apollo 15, asleep at this time. No word from them in a couple of hours or more. Present distance from the Moon; 21,006 nautical miles [38,903 km]; velocity now 3,827 feet per second [1,166 m/s]. Maroon team of Flight Controllers settled in for the night shift. And, at 232 hours, 28 minutes Ground Elapsed Time, this is Apollo Control."

Public Affairs Officer - "This is Apollo Control at 233 hours, 26 minutes Ground Elapsed Time. Apollo 15 crew still apparently asleep as they coast homeward from the Moon. Now at 23,194 nautical miles [42,955 km] out from the Moon, approaching Earth at a velocity of 3,795 feet per second [1,157 m/s]. Slightly over two hours, 2 hours and 18 minutes remaining in the scheduled sleep period. Flight controllers on the graveyard shift, here in Mission Control, watching a playback of the television from the three EVAs."

Public Affairs Officer - "This is Apollo Control. 234 hours, 44 minutes Ground Elapsed Time. 1 hour remaining in the Apollo 15 crew rest period. And, here in Mission Control, got a clock counting down to splash; showing now 60 hours, 26 minutes; which is tentatively the time from now until splashdown in the North Pacific just North of Hawaii. On the seventh of August. Apollo 15 now 26,130 nautical miles [48,393 km] out from the Moon, en route to Earth; velocity, 3,761 feet per second [1,146 m/s]. We'll bring that air/ground circuit live, hopefully prior to the first call to the crew in approximately an hour from now. At 234 hours, 46 minutes Ground Elapsed Time, this is Apollo Control."

[Flight Plan pages 3-345, 3-346 and the current page, 3-347.]
Public Affairs Officer - "This is Apollo Control at 235 hours, 45 minutes Ground Elapsed Time. And the clock has run out on the sleep period, rest period, scheduled for the crew. The spacecraft communicator Joe Allen preparing to call the crew for the wake-up call."

235:45:46 Allen: Good morning, Endeavour. This is Apollo Control in Houston, Texas, tuning the band [i.e. about to play some "wake-up music" to the crew]. Over. [Long pause.]

235:46:21 Scott: Good morning, tuning the band. This is Endeavour. Go.

235:46:30 Allen: Roger. Good morning, Endeavour. This is Houston with CSM consumables and a few good words about your Flight Plan, when you're ready.

235:46:46 Scott: Just stand by one.

235:46:48 Allen: Okay, Dave. And you troops sure start the day early up there, I must say.

235:46:59 Scott: Yes, seems that way, doesn't it?

[Long comm break.]
235:51:01 Scott: Okay, Houston. We've located the Flight Plan. Go ahead with your updates.

235:51:13 Allen: Endeavour, this is Houston. Were you calling?

235:51:21 Scott: Roger, Joe. We've located the Flight Plan. Go ahead with your updates.

235:51:27 Allen: Okay, Dave. I guess, let me start with the CSM consumables. At 235 plus 30, RCS total, 41; quad A: 43, 40, 38, 41; H2 tank 1, 41, 40, 36; O2 tank 1, 56, 58, 45. And the only immediate other thing I have for you, Dave, is a comment on the maneuver at 236 hours - about the Gamma-ray boom retract. We'd like for you to confirm - I'll be back when...

[Comm break.]
235:53:31 Allen: 15, this is Houston. How do you read?

235:53:38 Scott: Last I heard was gamma-ray. Go ahead.

235:53:42 Allen: Okay. The rest of that mysterious transmission is essentially the following, Dave. We've got a funny in that gamma-ray experiment and - so we're going to - to want to modify the use of it a little bit today. It should be no major imposition, but the Flight Plan calls out far the Gamma-ray boom to be retracted at 236 hours. We'd like to modify that by saying, turn the Gain Step, Shield, Off, at that time and we'll want you to retract it about 10 minutes later. We'll give you a cue for that. Over.

235:54:27 Scott: Okay. Gain Step, Shield, Off, at 236 and stand by for your cue for retraction.

235:54:36 Allen: That's correct, Dave. I've got a few other good things here, but there's no hurry on any of them. [I would] be willing to stand by, if you wanted to get squared away and give me a call later, or whatever you'd like to do. It's your preference.

235:54:54 Scott: Well, let's go ahead, Joe. We're getting squared away up here.

[Scott, from the 1971 Technical Debrief - "It seems like, particularly with the SIM bay, that we really never had enough time to do our housekeeping. We were always busy trying to keep up with things. I'm not sure whether it was because of the amount of equipment on board or because we had to constantly pay attention to our SIM bay operations. But it seems like we were always pressed on the housekeeping. We had to eat fast, had to get ready for the next thing fast, and, in general, we never had a lot of time to sit around and wait to get to the Moon; nor did we have a lot of time to sit around and wait to get home. We always had something to do. And it was mostly because the housekeeping took a fair amount of time.]

["One thing we all commented on was that it would be better if, when you awaken, you ate first and took care of your cleanup activities before you got into the operational part of the day. To try and combine operations with eating sort of compromised both. A guy would be halfway through fixing a meal and he'd have to go turn on some SIM bay thing, which means you didn't do either one very efficiently. After waking up, you should eat, clean up and then go to work. You'd be more efficient.]

["There are a number of things you have to do in the spacecraft which aren't really called out in any time line. We have an eat period and then we have a rest period and vice versa. You can't go from an eat period to a rest period. There are a lot of things that have to be done, most of which are called out in the presleep checklist. You can't just go finish your dinner and in two minutes do the presleep checklist and go to bed. You have to have a transition period during which you chlorinate the water, change a canister, everybody take their last urination for the day, and clean things up in general. You have to have a period of time there to get ready to go to bed."]

235:54:58 Allen: Okay. If you have the Flight Plan then, let me add the following. At 236 plus 45, add the step, "X-ray to On". And then turning over several pages...

235:55:25 Scott: Roger. 236:45; X-ray, On.

235:55:27 Allen: Okay. And turning over several pages to 241 plus 25.

235:55:43 Scott: Go.

235:55:44 Allen: Roger. After the step "O2 heaters 1, 2 and 3 to Auto", add "O2 tanks 1 and 2, 50 Watt Heaters, Main B, two, to Open."

235:56:31 Scott: Roger. 241:25; O2 Heater - or O2 Tank 1 and 2, 50 Watt Heaters, Main B to Open, and O2 Tank Heater - They're 50 Watt also? Main A, one, Open?

235:56:54 Allen: Stand by, Dave. I'm sorry about this one. Stand by.

235:57:01 Scott: Okay. [Long pause.]

235:57:26 Allen: Okay, Endeavour. Let me try that again. Had a typographical error down here. It should read "O2 Tank 1, 50 Watt Heater, Main B, 1, Open"; and "O2 Tanks 2 and 3, 50 Watt Heaters, Main A, 2, Open". Over.

235:57:53 Scott: Okay. O2 Tank 1, 50 Watt Heater, Main B, 1, Open; and Tanks 2 and 3, 50 Watt Heaters, Main A, 2, Open.

235:58:04 Allen: That's correct, Dave. I apologize for the slow start there. Now I've got some DAP load changes that cover the times from about 247 hours to 252 hours. And - the change is apparently because of a mis - of a mistake in the Flight Plan you have on board that we, in the meantime, have caught down here. And - so there are several deletions and additions during that time. The first one starts at 247 plus 28.

235:58:44 Scott: Go ahead, I've got it.

235:58:48 Allen: Okay. Delete your Verb 48, 11111 and X1111, and add - stand by a second.

235:59:09 Scott: That's twice.

[Dave Scott and Joe Allen work well together and it is likely Dave is teasing Allen about the frequency of his pauses during these updates. Joe is reading up a revised DAP load status. These are the numbers that are entered into the computer to make the DAP operate in a desired fashion.]
235:59:14 Allen: I'll be very careful from here on. Stand by. [Long pause.]

235:59:59 Allen: Okay, D.R. [i.e. David Randolph Scott] I'm ready to try it again. You've deleted at 247:28 the line with all the funny number ones, and you're supposed to delete, in the DAP load column, also that same entry. It's in the time column, I guess. And then turn the page.

[Flight Plan page 3-348.]
236:00:14 Scott: Yes. Roger.

236:00:15 Allen: Okay. Go to 248 hours, on the next page, and in the note column, change the DAP load status to read 11101. And the rest is the same. And this DAP load status continues through the PTC until 251 hours. And the next change is at 251 hours and 4 minutes.

236:01:10 Scott: Okay. 251:04, and I got the other three changes. Go ahead.

236:01:17 Allen: Okay. Delete the Verb 48 line and the DAP load over in the time column there.

236:01:37 Scott: Okay.

236:01:38 Allen: And the next change is at 251:47. Delete the Verb 48 line and the DAP load in its corresponding time column.

236:01:58 Scott: Okay. And I guess over in the notes column, we're still carrying 11101. Right?

236:02:06 Allen: That's affirmative, Dave. And starting at 252 hours, your DAP load status should read 111 - Stand by. [Pause.]

236:02:29 Allen: Okay. Let me try again. Starting... [Long pause.]

236:02:57 Allen: Okay starting at 252 plus 00 hours, in the notes column, the DAP load status should read 11101 times 1111 [means 11101 X1111]. And this should be carried through the rest period until 261 hours. Over.

236:03:31 Scott: Okay, Joe. You were saying something there about 252:30, as we lost comm. I got the entry at 252:00. Was there any change at 252:30?

236:03:43 Allen: Negative, Dave. The change at 252:00 should just be continued through until 261 hours. And that's just the DAP - DAP load status - should be changed correspondingly through until that time.

236:04:05 Scott: Okay. I see. And then we're - we're just 11101 all the way.

236:04:10 Allen: That's correct. [Long pause.]

[This long series of changes are really intended to make a simple change to the status of the Digital Auto Pilot, the routine in the computer that maintains the desired spacecraft attitude. The setting of the fourth bit to a zero has the effect of changing the deadband from ±5° to ±0.5°, essentially tightening up the control of the PTC rotation and maintaining it throughout the day and rest period.]
236:04:29 Scott: Okay. Go ahead with your next.

236:04:37 Allen: Dave, that's all I've got for the time being. And I think I'd be afraid to go ahead much further, if you're really counting these times. Maybe I should start keeping score on you as well.

236:04:52 Scott: [Laughter.] Okay.

236:05:00 Allen: We're happy for the time being. We're - we're standing by for a crew status report at your convenience. And we'll be watching for the Gain Step Shield to come Off.

236:05:15 Scott: Okay. We'll get right back with you in about 5 or 10.

236:05:18 Allen: Thank you.

[Comm break.]

[The discriminator in the Gamma-ray Spectrometer has been switched off and the crew are waiting for a cue from Mission Control to retract the boom on which it is mounted. Meanwhile, Al Worden stops the PTC rotation and proceeds with a P52 realignment of the spacecraft's gyroscopically stabilised guidance platform. The platform will be realigned to the orientation defined by the PTC REFSMMAT and as a reference, Al will use two stars, Aldebaran and Procyon. The amount by which the three gimbals supporting the platform must be rotated or torqued is to be reported to Earth but Mission Control can see them appear on the CM's DSKY (Display and Keyboard) as it is monitored via telemetry.]

236:18:01 Allen: Endeavour, this is Houston. We'd like for you to retract the Gamma-ray boom for us, please, and we'll be watching for your torquing angles. Also, if you'd like some news reporting in the background, I have the morning news here, if you're interested in that at all. Over.

236:18:27 Scott: Rog. Gamma-ray going to Retract now, and stand by on the news.

236:18:39 Allen: Okay. Roger. You can use that for background for the P52, I guess. President Nixon in effect declared US responsibility for offensive ground combat operations in Vietnam at an end. With the draft still in limbo, Selective Service went ahead today with the lottery to determine the order in which next year's nineteen-year-olds will face military service. Secretary of State William P. Rogers plans to go to the United Nat - Nations to push for a more energetic international relief effort for East Pakistan today. The Senate Armed Services Committee completed action on a 21 billion dollar military buying bill that meets most Nixon Administration weapons requests. President Nixon and his family will fly to Manchester, New Hampshire, and then to a private island in Maine this weekend, when visits to New Hampshire also are planned by four Democratic presidential hopefuls and Republican challenger Rep - Paul N. McClosky, Jr. Predicted weather for recovery day is 2,000 feet scattered, 10 miles vis, and waves approaching 6 feet. Wind is north by northeast, 18 knots. I have a long list of baseball scores here, which I'll just glance over. In the American League, New York beat Cleveland 7 to 3. I have here a local request for the Dodgers who lost to the Astros 2 to 0. The American Classic Golf Tournament starts today at the Firestone Country Club in Akron, Ohio. And the winner will get $30,000 dollars. Sounds to me like the pay's pretty good, and I expect the hours are short. The US Pan American Team went on a fantastic Gold Medal spree yesterday, winning 17 - rather 16 of the 17 medals at stake. The only one the Americans escaped getting was the Gold Medal in weight lifting. And the total in the games, which are being held in Colombia, is 78 for the United States, 36 of them gold, and 51 for Cuba, 12 of them are gold. And I'll end with the story comparable all the way to that incredible contest between the Apollo 15 All Stars and the North American Rockets. Last night in the Texas League, 21-year-old right-hander Tom Walker, pitching far Dallas-Fort Worth team, pitched a 15-inning, no-run, no-hit game against Albuquerque. He retired the last 21 men in a row. Only four Albuquerque players got on base and all of them were on walks. Walker got the first 18 batters out before he walked the first one. He threw 153 pitches in the game, and the no-hitter is an all time record in the Texas League and may very well be an all time record in Major League Baseball. Walker's manager told him that if he did not win the game in the 15th inning, he was going to have to pull him out. Walker said his arm felt a little tired, but he felt okay, understandably. Like doing three EVAs I expect. And that's all the news for - for this morning.

236:22:42 Scott: Boy! It sounds like he's as good as our very own Blinky.

236:22:49 Allen: That may well be, Dave. I - That never occurred to me.

236:22:57 Allen: At least the equal thereof.

236:23:02 Scott: Roger. At least almost.

[Comm break.]

[Once the P52 is out of the way, the Flight Plan calls for a period of cislunar navigation exercises. This requires Al to make a series of sightings of the Earth and stars as part of his brief to be able to get Endeavour home should communication with the Manned Space Flight Network be lost. The data from these sightings are processed by program 23 (P23) in the computer. Although a box in the Flight Plan claims that this exercise "will be performed on a non-interference basis with other crew activities", both the crew and flight controllers act as if it is essential. The Flight Plan also has the P23 exercise before breakfast but, as later comm reveals, the crew are getting on with eating to they can get tidied up prior to the EVA.]

236:25:17 Allen: Endeavour. We've copied the torquing angles. Thank you. And, Dave, if you can get a volunteer to work on the Mapping Camera for us, we'd like to try to pull that Mapping Camera in and get the covers closed in preparation for the EVA. We're not quite sure the position that the camera's in right now and the procedure I'll - can read up step by step, but it's basically to open the covers, try to extend the camera, we'll confirm the extension, and then we'll have you retract the camera and ultimately retract the covers. And I'll be standing by for your advice on this. Over.
[After the final use of the Mapping Camera yesterday evening, the crew found that it would not retract into the SIM bay. After some troubleshooting before the start of the rest period, it was decided that it could be safely left out without danger to the film within its magazine as long as the spacecraft was rotating in PTC and the heat loads spread. However, the PTC has ceased and will not be restarted before Al carries out his EVA. There is some worry that the film may suffer temperature extremes.]
236:26:08 Scott: Okay, Joe. We'll see if we have time to work on this. But, it's my understanding we do not have to have it retracted for the EVA.

236:26:28 Allen: Dave. That's my understanding, too. I think - the main reason - for wanting to do this if time is available and it's, o - and it's only - would be a nicety - would be it - gives us a warm feeling regarding the film. [Long pause.]

[Journal contributor Dave Edwards suggests that the broken nature of Allen's comm may be due to him relaying information to the CM while listening to the back room engineers. He sorts it out in his head and gives it a second try.]
236:27:41 Allen: Dave, just to complete that last statement, you're correct. We don't have to have that device retracted for the EVA. But, apparently, it - it gives the film people a nice feeling regarding their film not getting too cold or too hot. That's the reason for that.

236:28:02 Scott: Okay. Well, let us see if we can get to it.

236:28:05 Allen: Roger. Just give a whistle.

236:28:10 Scott: Okay. And we sort of flip-flopped that P23 and eat period so that we could take advantage of our setup for eating and all. And we'll get on with P23 as soon as we finish breakfast.

236:28:23 Allen: Sounds good.

[Comm break.]
236:29:43 Allen: Apollo 15, this is Houston. All other things being equal, troops, we'd prefer that you do the P23 before you begin the eat period, because it gives us an hour of pointed X-ray data during your eat period.

236:30:06 Scott: Okay, Joe; but I guess the inequality is the stowage situation in here and assuring that we can get properly prepared for the EVA. So - we'll start the P23 in probably about - oh - 5 minutes or so, because we're almost through eating. But we sort of have to take advantage of our configuration in here in order to stay with the time line later on.

236:30:29 Allen: That's fine, Dave. We understand, thank you.

[Very long comm break.]

[As the Commander, Dave uses his situational awareness in the Command Module to ensure they keep ahead of the timeline. His motto, practised while on the Moon, is "Get ahead and stay ahead." He works effectively with the flight controllers to negotiate the best outcome for the mission and its objectives.]

[Meanwhile, Al begins the procedure for navigating the CSM home without Mission Control's help, using P23 and sightings on stars and the Earth.]

[Prior to taking the sightings, he places Endeavour's attitude control to "Free" and back to "Auto". The DAP status bit that determines the deadband is set to narrow it to ±0.5°, then he maneuvers the CSM to the optics calibration attitude. A sighting is made on star 20 (Dnoces) to provide a calibration of the spacecraft's optical system. Finally, he maneuvers the CSM to the sighting attitude. Here he makes three sets of angle measurements from the Earth's horizon to one of three stars; Bellatrix, in Orion; Pollux, in Gemini; Capella, in Auriga. These angles allow the computer to determine the spacecraft's position and velocity in space with respect to the Earth.]

[Worden, from the 1971 Technical Debrief - "We tried to follow the no-comm schedule on the P23s, and there were some periods where we couldn't follow that because of some other things going on. But, I felt that the on-the-job training on the way out was very valuable, because when we started those P23s on the way home, I had a pretty good feeling for what had to be done and how to handle that whole program. Even after the first set of P23s, we had a pretty good feeling about the computation of the onboard state vector because the ground called up and said that they weren't going to update our state vector because our vector was almost as good as theirs.]

["I think the reason the P23s worked out as well as they did was the fact that I'd done considerable work at MIT on their simulator practising P23s. That made a great deal of difference to me. I had a much better understanding of which horizon to look for and mark on and of how to maneuver the spacecraft with minimum impulse, which can be kind of tricky."]

[Scott, from the 1971 Technical Debrief - "Especially with a light spacecraft."]

[Worden, from the 1971 Technical Debrief - "Especially with light spacecraft. It is really responsive to even minimum impulse. The system of doing the P23s, the maneuvering that we did, and the procedures for going through the P23s worked even smoother in flight than it ever had in the simulator."]

[Scott, from the 1971 Technical Debrief - "The overall concept of how the state vectors were updated and continued on board worked very well. It was obvious that we kept our onboard state vector comparable to the ground state vector all the time. There was no question that we could have completed the navigation on board and made a very acceptable, if not precise, reentry with an onboard vector all the way."]

[Worden, from the 1971 Technical Debrief - "Yes. I definitely had that feeling.]

["One more comment about the P23s before we leave that area. The Earth was a very thin crescent when we did the P23s on the way back home. We had some discussion preflight about taking marks toward the limb of the crescent on the Earth. You don't want to get out too far on the limb. All the stars that were picked were pretty much in the center of the crescent. Never had any problem locating the horizon working on that part of the crescent or taking those marks which kind of surprised me. It's a lot easier than I thought it would be."]

236:43:20 Allen: Endeavour this is Houston,

236:43:29 Scott: Go ahead.

236:43:31 Allen: Roger. I've got some information about your midcourse [correction opportunity] 5, which is scheduled to come up here [at 238:46]. We have a firm decision that there will not be a midcourse 5 maneuver required and the numbers behind that are a Gamma of minus 6.69 [degrees, with respect to the local horizon at Entry Interface]; your vacuum perigee is 18.4 [nautical miles, 34.1 km], and the midcourse 5 correction that we're showing now would be 3/10ths of a foot per second. The corresponding midcourse 7 correction runs at about 1.8 feet per second. And, based on that new information, we're wondering if you're still interested in doing the UV photography at scheduled time we're waiting until after the - the EVA. And we're also wondering what your choice will be on the solar corona photography. Over.

[The deletion of midcourse correction 5 frees up an amount of time before the EVA. Yesterday evening, Dave asked to delay a session of ultraviolet photography until after Al gets back inside. Now that more time is available, Mission Control wonder if Dave wishes to reinstate the UV session, forgetting that his original reason for delaying it was that the equipment, (UV-capable lens, film) was stowed beneath other items in preparation for the EVA. Once they begin pulling items out, they begin floating about the cabin and almost take on a life of their own.]

[Note that the vacuum perigee, the lowest point of their path around the Earth had there been no atmosphere in the way, has dropped from last night's value of 40 km. This far out, the slightest change in their current velocity has profound influence on their final trajectory. By the same token, the inevitable error range in their knowledge of their state vector (velocity and position), leads to a substantial range of uncertainty regarding that final trajectory. As they approach Earth, the error range will narrow and the size of further midcourse corrections will become better known.]

236:44:39 Scott: Okay. That's pretty fantastic guidance, ain't it? Let us - take another look at the Flight Plan here and come right back at you.

236:44:47 Allen: Okay, Dave; fine. And no hurry on - on the - on that decision. We would like the Gamma-ray [Gain] Step Shield, On, now, please.

236:45:06 Scott: Okay. Gamma-ray Gain Step, On.

236:45:10 Allen: Thank you. [Pause.]

236:45:15 Scott: And, Joe, I guess on the corona photography, mag R has been ex - expended. And as far as the UV, is not so much a problem of time. It's a problem of stowage. It's stowed way down deep in one of Endeavour's lockers here and to get at it requires quite a bit of manipulation of bags. And that's the reason we wanted to delay that if it was possible.

236:45:41 Allen: Okay, Dave. We understand that. And that - that sounds like it's a far more reason - reasonable to delay that. The timing is not critical as far as we're concerned. We just wanted to give you a balanced workday.

236:45:58 Scott: Okay; fine. We don't mind loading up a little after the EVA, because it really saves us a lot of work in the long run. And you might wonder why we didn't put - the UV stuff somewhere else, but there's just nowhere else to put it but in it's - in its own proper little spot.

236:46:44 Allen: No, we understand. Thank you.

[Very long comm break.]

[With the P23 exercise completed, Al maneuvers the spacecraft to an attitude required for the second period of X-ray astronomy, this time aiming the X-ray Spectrometer at a mid-galactic latitude. This area of the celestial sphere will provide control data for subsequent measurements, essentially characterising the background flux of x-rays from space.]

236:57:46 Scott: Houston, 15.

236:57:49 Allen: Go ahead, 15.

236:57:53 Scott: Okay. Have a crew status report for you, and you can have the docs take a look at the LMP bio[medical], see if that's acceptable.

236:58:00 Allen: Okay.

236:58:08 Scott: Ready to copy?

236:58:09 Allen: Go ahead.

236:58:14 Scott: Okay. 7 hours sleep apiece, and PRDs 25028, 23193, 08031.

236:58:29 Allen: Okay, Dave. Thank you. And we see that we've got the X-ray going. We'd like for you to change the setting on the Gain Step. Give us a one-click increase, which will move us from - the position 7 back to position 1. Over.

236:58:50 Scott: Okay. You've got a one-click increase.

236:58:56 Allen: Okay. We see it, Dave, and Jim's Bio looks clean to us down here. Thank you.

236:59:05 Scott: Okay.

[Very long comm break.]

[Flight Plan page 3-349.]

Public Affairs Officer - "This is Apollo Control. The crew reported, in the last exchange, that the - each of the three crewmen had a good seven hours sleep during the night. And also the ground advised the crew that the magnitude of midcourse number 5 - midcourse correction burn number 5, as shown by present tracking, is so small that it will be deleted. It's now showing around 3/10 of a foot per second. Meanwhile, the space flight meteorology group of the National Weather Service said this morning, that the end-of-mission weather conditions are expected to be satisfactory in the area north of Hawaii where Apollo 15 will splash down Saturday. The forecast is for scattered clouds with good visibility, east-northeast winds 15 to 20 knots, and seas to 6 feet. Temperatures will be in the upper 70's. Splashdown clock still counting, now showing 58 hours, 7 minutes to Apollo 15 splashdown. At 237 hours, 4 minutes Ground Elapsed Time, standing by on air/ground, until the crew is put to bed again tonight, this is Apollo Control."

237:15:05 Allen: Endeavour. Give us six clicks on the Gamma-ray Gain [Step] switch, please.

237:15:14 Worden: Okay. Six clicks.

[Very long comm break.]
237:35:59 Allen: Endeavour, this is Houston.

237:36:04 Scott: Houston, Endeavour. Go.

237:36:06 Allen: Roger, Dave. A couple of miscellaneous items I'd like to ask you about. First of all, the trench sends their congratulations to whoever's doing the P23 for us. The errors are less than one sigma - and they're awarding the honorary Vasco da Gama Navigation Award for excellence in this. Secondly, we're puzzling over your remark about magazine Romeo [the high-speed black and white film magazine], which you reported to us was exhausted. And we're wondering if you just read - the frame number from the mag and, if so, what it read. Over.

237:36:57 Worden: Yes. Joe, this is Al. The last reading of Romeo, I think, was 110.

237:37:10 Allen: Okay, Al. Thank you. And were you doing the P23 for us?

237:37:17 Worden: Si. [Pause.]

237:37:23 Allen: Okay. I'll tell you a little something about Vasco da Gama later on. Another easy item here; you're going to come up on a bat[tery] charge - I guess Bat B charge - starting at 239 hours, and we'd like to delay that to 244 hours, please.

237:37:46 Scott: Okay. Delay the Bat B charge to 244. And be advised - you've got to know that we've got best navigator in trans-Earth lunar space up here.

237:38:00 Allen: At least one of them, I'm sure.

237:38:01 Scott: In fact, the only one.

237:38:03 Allen: Roger. We copy. And, finally, I'd like to get a volunteer to take a whack at this - configuring the Map Camera properly. And it's going to be a few short steps, and if it works, great; we'll have a lot of good engineering data regarding the thermal properties of that beauty. And if it doesn't work, we're just going to turn it off and leave it. And - when somebody's ready to do that, I'll go through the steps. There are not too many.

237:38:36 Scott: Okay, Joe. Somebody'll be ready in just a few minutes.

237:38:40 Allen: Rog. Thank you, Dave.

[Long comm break.]
237:46:42 Scott: Okay, Houston; Endeavour. If you want to try your camera techniques again, let's give it a whirl.

237:46:49 Allen: Okay, Endeavour. I've got five steps here, and I think it's easiest for me just to read them to you and have you carry them out rather than copying them down. And the first one - first two steps...

237:47:01 Scott: Rog.

237:47:02 Allen: ...on panel 181, verify Logic Power, Main A circuit breaker, Closed.

237:47:16 Scott: Okay, verified.

237:47:17 Allen: And same panel, verify Logic Power switches, two of them, to Deploy/Retract.

237:47:26 Scott: Verified.

237:47:28 Allen: Step 3 on panel 278, the Experiment Covers Deploy circuit breaker, Main A to Closed.

237:47:44 Scott: Verified. Closed.

237:47:47 Allen: Step 4 on panel 230, the Map Camera, verify Standby.

237:47:56 Scott: Verified to Standby.

237:47:59 Allen: Okay, and coming up on step 5 and let me read through this - and - I'll stand by for questions then, if there are some. We want the Map Camera Track to Extend; and, simultaneously, we want the Experiment Cover Map Camera/Laser Altimeter to Open, and we want those two things done simultaneously.

237:48:33 Scott: Okay. Understand. Go to Extend and open the Covers, Map Camera/Laser simultaneously.

237:48:37 Allen: Roger. And a note on that - I guess - on the Map Camera Track to Extend, we'll be watching that for about between 4 and 5 minutes or until you get a gray talkback on there. And - we think this is going to clear up our problem and if it doesn't, we're just going to turn the whole ball of wax off and go ahead and do the EVA as normally planned. Over.

237:49:13 Scott: Okay, Joe. In three seconds, we'll execute.

237:49:18 Allen: Roger, Dave. We're watching. [Long pause.]

237:49:32 Scott: Well, I got a gray on the Mapping Camera. How 'bout that.

[The talkback indicator for the Mapping Camera's Extend/Retract function is meant to show barber pole (striped) while the camera is on the move. When it reaches the limit of its travel, the talkback changes to gray. Since they tried retracting it last night, it has been barber pole. The gray indication Dave has seen means that the camera is fully out again and the short length of time taken implies that it had hardly moved in on retraction.]
237:49:43 Allen: Okay; stand by. [Pause.]

237:49:53 Allen: Dave, do you have a gray on the door as well?

237:49:59 Scott: That's affirm, but I did not get a barber pole on the door. It just stayed gray.

237:50:06 Allen: Okay; that's good. That just means that it was open already.

237:50:13 Scott: Right.

237:50:15 Allen: Okay. Then that - that's worked out fine. Apparently, we were having a temperature problem with that thing before, and we're back in business just like normal. We'd like now the Mapping Camera Track to Retract, and that'll take I guess about 4½ minutes.

237:50:38 Scott: Okay. Map Camera Track going to Retract now.

[Long comm break.]
237:56:57 Allen: Endeavour, this is Houston. Be advised that because we're not going to do a midcourse 5, we'll continue the X-ray pointing to about 238 plus 30, and we'll be coming at you with a list of the steps at 238 hours that you can delete because we're not doing the midcourse.

237:57:23 Scott: Okay. Fine. [Long pause.]

237:57:44 Allen: And, Dave, could - could you have someone check the barber pole on our Map Camera, Track, to see if you have the gray-Retract indication, please.

237:58:01 Scott: Roger, Joe. I been watching it. You got about 7 minutes and 20 - 20 seconds now and it's still barber pole.

[The indication means that the Mapping Camera is still stuck, likely near its extended position.]
237:58:10 Allen: Okay. That's what we're showing down here. And stand by. [Long pause.]

237:58:28 Allen: Okay, Endeavour. We're satisfied with that Mapping Camera exercise. Two more requests on that. Go to Off with the Extend/Retract switch, and to Off with the Mapping Camera/Laser Altimeter Cover switch, please. And we're finished with that.

237:58:54 Scott: Okay; Extend/Retract to Off; and a Map Camera/Laser Altimeter's going of Off.

237:59:03 Allen: That's right, Dave. And a note for Al. We think that the magazine Romeo, based on the frame count you gave us, still has enough frames left to take the solar corona pictures. And we'll have some special words for Al on how he's to take those pictures. I guess, we'll delete a few of the solar corona requirements. Also, word about the PRD configuration for the EVA. Apparently, we'll want the CMP to have the PRD whose number reads 25028. And, I guess, that's the one you've been carrying, Dave. And, Jim, we'll - we'll use the one that reads 08031, but we would like to have him reconfirm this number before he starts the EVA. Over.

[Flight Plan page 3-351.]
238:00:13 Scott: Okay. Let me get that checklist here Joe; standby. The CMP is 250 - say again.

238:00:22 Allen: Roger. We want Al to wear the PRD that's now reading 25028. That will distinguish it from the other two with no ambiguity. And Jim to take the one that begins 080, and we want him to give us the full reading off of that before he start the EVA, though.

238:00:46 Scott: Well, we'll have to give it to you now, because it will be in the suit and we won't be able to get to it.

238:00:50 Allen: That's fine. Any time. Any time. [Long pause.]

238:01:28 Scott: Okay. The one Jim will wear will be 08037.

238:01:37 Allen: Okay, Dave. Thank you. And if you'll give us P00 and Accept, we'll let you have a new state vector.

238:01:49 Worden: Rog. You've got it.

[Comm break.]

[Program zero-zero is the computer's 'do-nothing' state which is appropriate for those times when Mission Control were updating areas of its memory by radio link. Apollo crews usually referred to this program as P00, pronounced "Pooh" as in the classic children's character invented by A. A. Milne.]

238:04:33 Allen: Endeavour, it's your computer.

238:04:37 Irwin: Roger.

[Comm break.]
238:06:06 Scott: And, Houston; Endeavour. [Do] you want to go through the change in the Flight Plan at 238 hours, if you haven't?

238:06:13 Allen: Standby. [Long pause.]

[These are deletions intimated by Allen ten minutes ago.]
238:06:34 Allen: Okay, Dave. This involves delaying the SIM bay turnoff until 238 hours and 30 minutes. And in detail, at 238 plus 05, delete the P30 external Delta-V, and the Verb 49 maneuver. Lines: at 238 plus 20, delete sextant star check; at 238 plus 28, delete all the steps from there starting with circuit breaker SCS, et cetera, up to 238 plus 55, ending with RHC Power Direct, two, Off, et cetera. Over.

238:07:41 Scott: All right. I got all that. Thank You.

[Long comm break.]

[From this point, the crew can begin their preparation for the EVA. The only other item prior to that are the taking of a few images to calibrate the solar corona pictures taken earlier in the mission.]

Public Affairs Officer - "This is Apollo Control. Coming up in a few seconds, on Apollo 15's exit of the Lunar Sphere of Influence."

238:14:37 Allen: Hello, Endeavour, this is Houston.

238:14:43 Scott: Houston, Endeavour. Go.

238:14:45 Allen: Be advised at my mark, you are leaving the sphere of lunar influence; and it's downhill from here on in.

238:14:54 Allen: Mark.

238:14:59 Scott: Roger, Thank you, Joe. That's nice to know.

238:15:07 Allen: Did you notice anything there, Dave? Discontinuity in velocity or anything like that?

238:15:17 Scott: Well, Joe. That's one of the mysteries that we'll probably have keep to ourselves.

238:15:22 Allen: I was afraid of that.

[Long comm break.]

[After 7¼ days having the Moon as its chief gravitational influence, Endeavour now "feels" the gravity of Earth as the stronger force and its velocity begins to increase. Trajectory computations are changed over to be Earth-centric and the Moon's velocity in its orbit is taken out of the reckoning.]

[The conversation between Joe Allen and Dave pokes gentle fun at the news media's inability to fully grasp the concepts behind this imaginary boundary. Many continued to believe that there was a physical jump felt by the crew, a belief perhaps fed by the jump in the velocity numbers due to the change in reference frame.]

[Woods, from 2000 correspondence - "Was this the inspiration behind this exchange?"]

[Scott, from 2000 correspondence - "Well, that's one of those little mysteries that we'll have to leave for future researchers....!!!! It all goes along with the culture of lunar exploration!"]

238:21:56 Allen: Endeavour, this is Houston.

238:22:02 Scott: Go ahead.

238:22:03 Allen: Roger, Dave. We're looking down the line here towards the EVA. And the Surgeon's getting good biomed data on Al now, except one of the three EKG sensors is apparently marginal, and there's some noise creeping in. We're just wondering what your standard procedure is regarding sensoring before the EVA exercise. If he's going to resensor, it's probably no problem; if he's not planning to, maybe we ought to talk it a little. Over.

238:22:37 Scott: Okay. We're all three all sensored, ready to go. If they have a problem, let's get it squared away right now.

238:22:45 Allen: Okay. Do you have, - Maybe Al could try pressing down on the three EKG leads, one at a time, for us; that may help us out.

238:23:01 Scott: Okay. Here we go. The upper right.

238:23:17 Allen: Okay.

238:23:22 Scott: Okay. The upper center is being pressed.

238:23:36 Allen: Okay.

238:23:41 Scott: Okay, the lower left. [Long pause.]

238:23:57 Allen: Okay. Stand by.

238:24:02 Scott: Okay. [Long pause.]

238:24:56 Allen: Dave, it looks to us like it's one of the two top sensors, and we were wondering how difficult it would be to reseat both of them now.

238:25:11 Scott: Okay. I'll tell you what we'll do. A little further down the line here, we'll take care of both of those. We'll just reseat them and everything.

238:25:24 Allen: Okay, fine. Thank you.

238:25:29 Scott: And thank you for thinking ahead on that one.

[Very long comm break.]
Public Affairs Officer - "This is Apollo Control with the exiting [of the] Apollo 15 spacecraft [out] of the arbitrary and imaginary lunar sphere of influence. The displays in Mission Control, having to do with velocity and distance, switched over at that time from lunar reference to Earth reference. The crossing occurred at 238 hours, 14 minutes, 51 seconds. At this moment, Apollo 15 is 177,225 nautical miles [328,220 km] out from Earth, approaching at a velocity of 2,855 feet per second [870 m/s]. Landing clock showing 56 hours, 40 minutes until splashdown. Midcourse [Correction] 5 burn, because of its small magnitude, about three-tenths of a [foot per] second would be needed, will not be done, which allows the crew more time to take care of other items with the SIM bay equipment, do a little troubleshooting, and a little more pad time for preparing for today's EVA by Al Worden in which he will go hand over hand back to the Service Module to retrieve film cassettes from the Mapping and Panorama Cameras. At 238 hours, 31 minutes Ground Elapsed Time, this is Apollo Control."

[Preparation for the EVA will begin with powering down the instruments in the SIM bay, retracting the booms and closing covers.]
238:43:21 Allen: Endeavour, Houston.

238:43:28 Scott: Houston, Endeavour. Go.

238:43:30 Allen: Roger. I've got an update to your corona - window calibration photography and the UV photographs, when you're ready.

238:43:45 Scott: Okay. Stand by one.

[Comm break.]
238:46:24 Scott: Houston, Endeavour. Can't seem to get the Mass Spec. boom all the way in and I guess Al's had a little trouble with it - now and again with the barber pole being half - the talkback being half barber pole. And seems to flutter there, close to the gray position, and doesn't really come all the way in.
[Deployment of the Mass Spectrometer's boom has been an increasing problem throughout its use. The problem is correctly suspected to be caused by the mechanism being affected by cold. The spacecraft is being held in a constant attitude and if heat from the Sun cannot get in to warm the boom's systems, they quickly radiate their heat into space.]
238:46:47 Allen: Okay, Dave. We copy. Let us think about that.

238:46:53 Scott: Okay. And we're going ahead with the dumps, if that's okay?

238:47:05 Allen: Okay. [Long pause.]

238:47:17 Scott: And if you'd like a visual check of just exactly where that's hanging up, why we can give it to you in a couple of hours. We'll have Al go out and take a look.

238:47:26 Allen: That's not a bad idea. Does he know about this plan yet?

238:47:32 Scott: Well, I don't know. We'll check with him. Yeah, he nods his head like he'd probably be obliged to do it.

238:47:40 Allen: Okay. Break it to him gently, though.

238:47:44 Scott: Okay.

238:47:46 Allen: And, Dave. While I got you here, I do want to comment that the first change in the Flight Plan is to delete the step at 238 plus 23 that says "enable all jets." We think that there is a - a certain chance that Map Camera may be stuck out, and we particularly don't want RCS jets A4, A2, B1 and B4 to be enabled, because they may give us trouble with that camera.

238:48:30 Scott: Okay. Understand, Joe. We'll scratch that step and make sure A4, A2, B1 and B4 stay off.

[The four RCS thrusters mentioned are those whose exhaust would, if used, most likely impinge upon the Mapping Camera. A photograph taken of Endeavour during the rendezvous shows the relationship of this camera to these jets.]
238:48:38 Allen: Okay. And I'll - Standing by to read you some more photo PADs, just at your convenience.

238:48:48 Scott: Go ahead. I've got the Flight Plan out.

238:48:55 Allen: Okay. If you'll turn to page 3-352, which is the Corona Window Calibration and UV photos procedures page.

238:49:11 Scott: I've got it.

238:49:15 Allen: Okay. The attitude involved in the corona photographs should read 057, 005, 025. And the time on that, 239 plus 08. And the High Gain [Antenna] numbers, pitch, minus 48; yaw, 238.

238:50:03 Scott: Okay, Joe. 057, 005, 025 at 239:08. Minus 48 and 238 for the High Gain.

238:50:13 Allen: That's correct, and moving down a couple of lines, the shutter speed should be changed from 1/500th to 1/125th. And change the inhibit jets line to read "damp rates for 5 minutes." CMC Mode to Free.

238:50:58 Scott: Okay. Understand. Scratch inhibit jets, and substitute damp rates for 5 minutes, and then CMC, Free, and the 1/125th replaces the 1/500th on the camera.

238:51:11 Allen: That's correct, Dave. And moving down a little further, delete the line, "cycle 1 frame, change shutter" and delete the line "cycle 1 frame." And finally, change the last line, enable all jets to read, "CMC Mode, Auto."

238:52:44 Scott: Okay, delete line, "cycle 1 frame" and "cycle 1 frame"; and CMC Auto, replaces "Enable all jets".

238:52:52 Allen: That's correct and assuming you're going to take the UV photographs after the EVA, I have a photo PAD for that, if that assumption is correct.

238:53:06 Scott: Looks like that assumption is probably correct, Joe, and we'll take the photo PAD later on. Let us get on with corona [photography], or we won't make it.

238:53:14 Allen: Okay. Sounds good.

[Long comm break.]
238:57:25 Allen: Apollo 15, Houston.

238:57:34 Scott: Houston, 15. Go.

238:57:36 Allen: Roger, Jim. We understand you are going to delete [means postpone] the UV photographs, but after you complete the corona window calibration, you will have to do the first step in the UV photos trans-Earth coast procedures, there. And that first step is Verb 49 maneuver to Earth UV photo attitude, and it lists the attitude there. We need this for thermal reasons.

238:58:08 Scott: Roger. We'll do that.

[Long comm break.]

[Since the Passive Thermal Control was stopped three hours ago, the spacecraft has adopted various stable attitudes which have tended to heat one side of the spacecraft and chill the other. During the planning for the morning's activities, thought has been given to the temperature extremes sustained by Endeavour's systems, carefully balancing operational requirements with thermal ones. Mission Control want to ensure that after an extended period of pointing the X-ray Spectrometer to deep space, the heat load will be shared around the spacecraft's body. Therefore, the crew will maneuver to the UV photo attitude as planned even though they are not carrying out the photography. Once the SIM bay film magazines are retrieved, the thermal constraints will lessen.]

[Flight Plan page 3-353.]

239:05:41 Worden: Houston, 15.

239:05:45 Allen: Go ahead, 15.

239:05:50 Worden: Hey, Joe. Just a point of clarification on the backing to be used for the corona. I don't know whether you are aware or not, but the backing that fits into window 4, which is the right-hand rendezvous window, has two different mounting pads for the camera, one is 250 and the other is 80. And the 80 is pointing 12 degrees below the X-axis, and I just wanted to check and see if you wanted us - if that's the proper PAD or if you wanted us to use the 80 or the 250 pad.

239:06:23 Allen: Al, use the 80. The one pointing 12 degrees above the X-axis.

239:06:30 Worden: Okay, Joe. Thank you.

[Very long comm break.]
Public Affairs Officer - "This is Apollo Control; 239 hours, 19 minutes Ground Elapsed Time. Handover under way here in the control center as Gerry Griffin's gold team takes over from the outgoing shift headed up by Milt Windler of the maroon team. ... Apollo 15 now 175,871 nautical miles [325,712 km] out from Earth, approaching at a velocity of 2,885 feet per second [879 m/s]. Splashtime: 55 hours, 51 minutes away. Next major item of the morning will be the Command Module Pilot's EVA to retrieve film packages from the SIM bay. This will take place at 10:24 Central Daylight Time or 241 hours, 50 minutes Ground Elapsed Time, that is the cabin depress - the actual EVA will follow some 20 or 30 minutes after. At 239 hours, 20 minutes, up live on air/ground with Apollo 15, this is Apollo Control."
[The procedures for the EVA begin on page 3-1 of the CSM Systems Checklist.]
239:46:00 Henize: 15, this is Houston. [No answer.]
[Long comm break.]
239:50:45 Henize: Apollo 15, this is Houston. [No answer.]
[Comm break.]
239:51:47 Henize: 15, this is Houston, broadcasting in the blind, with a request that, if possible, we bring back Dave's LCG. If it's already stowed in too inaccessible place in the - in the jettison bag, don't bother. But if you can possibly save it, please bring it back.
[Mission Control want the LCG (Liquid Cooled Garment) that Dave was wearing three days ago when he and Jim Irwin returned from the Moon's surface. After re-entering the Command Module and while preparing to jettison the Lunar Module Falcon, he had trouble sealing the water connection to the LCG and had to use a plug instead. If returned to Earth, then analysis of the problem, believed to be caused by dust contamination, can be made in time for the next flight.]
239:52:08 Scott: Okay. Sorry, Houston, we were getting suited here, and didn't realize we were off comm; but we copied your request. Let us think about it some for a minute.

239:52:19 Henize: Roger. [Long pause.]

239:52:45 Scott: Well, Houston, I guess that it's a good reason we're about an hour ahead. So we'll go ahead and dig it out.

239:52:58 Henize: That's your choice, Dave.

239:53:04 Scott: Well, we're sort of ahead, and expecting little things like that to pop up.

239:53:08 Henize: Fine.

[Comm break.]

[Woods - "Suited and unsuited in the Command Module in weightlessness. Is that a particularly difficult task. Is it easier or more difficult than doing so on the Moon. You got three guys in a small space and no gravity."]

[Scott - "The only added difficulty in weightlessness is sort of getting to a position where the other guy can help you get in the suit and hold the suit. That's no big deal. The work on the suit is getting it zipped, getting it plugged, getting it checked. All that stuff. Yeah it was probably a little more difficult than... [laughs] They're both hard. If I say weightlessness is more difficult than one-sixth-g then the implication is that one-sixth-g is easy. Not easy. Very, very hard."]

239:54:11 Scott: Say, Houston, by the way, the LCG you'll get back is the one I wore on the third EVA only.

239:54:30 Henize: Roger; Dave. That's fine. That's the one we'd like.

239:54:35 Scott: Okay. Okay. [Long pause.]

239:54:56 Henize: And 15, whenever Al has a quiet moment, I have several prebriefing questions to send up to him about what to look for on the V over H sensor.

[The V over H sensor is part of the Panoramic Camera's system. The sensor optically determines the rate at which the landscape is passing below, allowing the camera to adjust for the smearing that would occur if uncorrected.]
239:55:08 Scott: Okay, give us about an hour for that, then we'll be able to talk to you.

239:55:12 Henize: Very good.

[Long comm break.]
Public Affairs Officer - "This is Apollo Control at 239 hours, 58 minutes. Apollo 15 now 174,778 nautical miles [323,688 km] from Earth. Velocity, 2,909 feet per second [887 m/s]. And the crew is in preparation for the EVA to retrieve the film cassettes from the Panoramic and Mapping Cameras."
[Flight Plan page 3-354.]
240:01:48 Henize: 15, this is Houston. We'd like to have Manual [pointing] on the High Gain whenever one of you has a chance to get there. No need to answer.
[Endeavour has probably been maneuvered to the required attitude for Al's EVA. Appropriate angles are given in the Flight Plan for aiming the HGA (High Gain Antenna). To use them, the crew assume manual control of the antenna's mounting gimbal and dial in the given angles using two knobs to the lower right of the Main Display Console, panel 2. Nearby gauges let them monitor the antenna's actual orientation.]

[Now that the spacecraft is in the proper attitude, the A and B thruster quads are disabled. These are adjacent to the SIM bay and would pose a danger to Al as the spacecraft constantly fires thrusters to maintain its attitude. Guard rails are installed over the centre of the Main Display Console to ensure that controls, particularly those concerning the RCS, are not nudged. The three crew don their suits, Dave and Jim wearing their surface EVA suits, and get connected to the spacecraft's suit oxygen circuit. Al's 7.4-metre umbilical is different in that it includes a tether connected between a fixing on the CM and a waist belt he will wear around the outside of his suit. The umbilical also carries wiring for communication and biomedical telemetry. Jim also has a waistbelt and a shorter, 2.2-metre tether as he will stand in the CM hatch during the EVA, helping control Al's umbilical, operate the TV and 16-mm cameras and bring the film cassettes into the cabin.]

240:01:58 Worden: Let me do it.

240:01:59 Scott: Okay. Go to Manual.

[Very long comm break.]
Public Affairs Officer - "This is Apollo Control at 240 hours, 06 minutes. Dave Scott reported a short time ago that the crew was about 1 hour ahead on the time line. We do not anticipate however that the EVA will start 1 hour early. We're staying keyed here to the normal Flight Plan time for EVA. If that changes we'll let you know that. At the present time, we do not anticipate moving the Flight Plan ahead. The liquid cooled garment that they have asked them to bring back is the one in which Dave Scott replaced a plug when they failed a suit integrity check about LM jettison time in lunar orbit. The experts on the ground would like to take a look at that garment."
[During this hour of communications silence, the crew continue their preparations for the EVA.]

[Scott, from the 1971 Technical Debrief - "On the night after TEI, Al started configuring the cabin, stowage-wise, so that we'd be set up for the EVA. I think he put at least 2 hours into configuring the cabin the night before."]

[Worden, from the 1971 Technical Debrief - "Yes. There was a lot of detail stuff, like putting things into the EVA bag, getting the purge valve out, and getting a lot of the little stuff out of the stowage containers. We tied the rock bags up to the sides of the spacecraft, rather than tying them down on top of the lockers. That way we could get in and out. Rearranging the stowage was kind of the detail part of some of the EVA prep that we did the night before."]

[Scott, from the 1971 Technical Debrief - "The point is that when we got into the EVA day - when we got up that morning for the EVA - the cabin was already in good shape. Everything was set up so that we could proceed into the EVA prep according to the checklist with a minimum amount of shuffling. At the outset, I'd like to say that the checklist was excellent. The procedures ran very smoothly. I don't think anything was out of order. We had a very complete set of procedures overall. Everything got done according to the book, and it was very good. The only problem was time. We got up that morning and we had a few SIM bay things to do. Al had some P23s to do, and as soon as he finished his P23s, we started into the checklist and the portion called "Cabin Prep for EVA." We started that at 237:30 GET. It's really called in the Flight Plan to start at 239:30, so we started 2 hours early in the cabin prep for EVA. We went through every step line-by-line to make sure it all got done. It flowed very smoothly with no hitches, and it just took a little time to get everything done. We ended up just about on time for the pressure integrity checks. That means that it took us almost 2 hours longer than preflight planning. We were very happy that we had started early. We were glad that we had Al configure the cabin the night before to take care of the little details. I think it will pay off if you get started early on the EVA, because it really takes a lot of time making sure that you get everything done."]

[Worden, from the 1971 Technical Debrief - "Most things you do on board take a little longer than you would expect them to preflight. That's because you take a little bit more care with what you're doing in flight. You do it much more methodically than you do preflight. That was particularly true of the EVA prep. We went through the checklist very carefully, very methodically, and we never rushed at any time. It flowed very smoothly but a little slower than we anticipated."]

[Scott, from the 1971 Technical Debrief - "Which I think was good in that case, because it was the first time through for that EVA. It was nice to have a comfortable time pad all the way through. We knew we had a good time pad all the way through, so perhaps we were not operating at maximum efficiency relative to time. We were taking our time because we knew we had the pad."]

[So that Mission Control, and the public too, can watch the progress of Al's excursion along the Service Module, a pole has been provided so that the colour TV camera and the 16-mm movie camera can be mounted far enough from the CM main hatch to gain a reasonable view of his activities around the SIM bay. The pole will be attached to the inside of the open hatch.]

[When Dave and Jim walked and drove on the Moon, they each carried a backpack called a PLSS (Portable Life Support System) which provided all the required consumables to keep them alive and fit for over seven hours. The PLSS provided oxygen, cooling water and scrubbed CO2 out of the air. If, however, a suit were to be punctured for some reason, the flow-rate from the oxygen supply would likely not be high enough to sustain the crewman against the falling pressure. For this contingency, both Dave and Jim carried an extra package on top of the PLSS called the OPS (Oxygen Purge System), the prime component of which was a very high pressure bottle of O2 which could be quickly released through a regulator. Though the PLSS's were discarded on the Moon, the two OPS units were retained in case Dave and Jim needed to transfer to the CM by an EVA. Now one unit will provide Al with his emergency supply during his EVA.]

Public Affairs Officer - "This is Apollo Control at 240 hours, 14 minutes. The CapCom Karl Henize, has been joined now by the backup crew Commander and Command Module Pilot, Dick Gordon and Vance Brand and by Donald K. Slayton, the Director of Flight Crew Operations."

Public Affairs Officer - "This is Apollo Control at 240 hours, 37 minutes. The crew is busy with preparations for EVA and Apollo 15 is 173,670 nautical miles [321,636 km] from Earth. Velocity 2,935 feet per second [895 m/s]."

[Flight Plan page 3-355.]
240:59:59 Scott: Okay, Houston. Apollo 15.

241:00:04 Henize: 15, this is Houston. Go ahead.

241:00:11 Scott: We're all suited up, and down to the comm check portion of the EVA prep, and we're ready to talk to you about whatever you'd like to talk about.

241:00:21 Henize: Roger. Stand by.

241:00:34 Henize: I guess the main thing we have to talk about is the inspection of the V over H sensor of the Pan Camera. Are you ready to listen, Al?

241:00:48 Scott: Okay. He can read you, but he's got to reconfigure his panel in order to talk to you, so we'll do that.

241:00:56 Worden: Okay, Karl, how do you read me now?

241:00:57 Henize: Loud and clear, Al. Hey, on this V over H sensor, I have a set of five steps, or five questions that we'd like to have for you to have in your mind.

241:01:09 Worden: Okay. Go ahead.

241:01:11 Henize: Okay. Number 1 is, inspect the general area - this is sort of a general point of view - inspect the general area around the V over H sensor and comment on any evidence of thermal or mechanical degradation. And 2, 3, 4, and 5 are sort of more specifically. Number 2. Is there any evidence of V over H sensor lens cracking, or debris on the lens? In other words, have a good check of the lens itself. Number 3. Is any large amount of the black paint around the V over H sensor opening missing? Number 4. Is the plume shield in place around the V over H sensor opening? And the plume shield is what I'd generally call the - or - the - it's the guard around the lens sticking out about 3 inches [75 mm] there. And, number 5. Is anything obviously obstructing the V over H sensor field of view?

Diagram showing layout of SIM bay.

[This illustration, taken from the J-mission Apollo News Reference, shows the layout of the SIM bay. The V over H sensor is to the lower right of the Panoramic Camera's lens. Though difficult to see on this picture, its plume shield is like a lens hood projecting forward. During the EVA, Al will engage his feet in the foot restraint to the left. Facing right, he will have access to the majority of the bay, particularly the film cassettes which he must retrieve.]

241:02:25 Worden: Okay, Karl. We got all those.

241:02:29 Henize: Okey doke. No other special questions at the moment. Stand by.

241:02:40 Worden: Okay.

241:02:42 Scott: Okay. We'll proceed on here then.

241:02:46 Henize: Incidentally, I guess we're - we both understand each other on the status of the Mapping Camera? So far as you know, it hasn't retracted. Is that correct?

241:02:58 Worden: That is our understanding at this point. I'll let you know when I get out.

241:03:02 Henize: Roger. [Pause.]

241:03:11 Henize: Oh, Al. One more point that I overlooked down here, and that is, the people here would like to have you look at the Mass Spec. boom, Al, if it's at all feasible. If it's not convenient to look down at the base of that boom and look at the coils, forget it; but if you can get a look in there, we would expect to find a coil crossover jamming down in the base there, and we'd like to have your visual confirmation of that.

241:03:39 Worden: Roger, Karl. I had intended to do that.

[Towards the latter part of the spacecraft's time in lunar orbit, Al began having problems retracting the boom carrying the Mass Spectrometer. This problem is discussed more fully earlier in this journal but its essence is that the boom mechanism sticks when it becomes cold.]
241:03:41 Henize: Very good. [Long pause.]
[The next exchanges are the crew's comm checks. Dave and Jim will use a PTT (Push to Talk) switch. Al will be on VOX, his transmissions being made automatically by a voice-operated switch.]
241:04:02 Worden: Roger. That's on.

241:04:04 Scott: Net comm, Off.

241:04:05 Worden: Net comm, Off.

241:04:06 Scott: S-band T/R.

241:04:07 Worden: S-band T/R.

241:04:08 Scott: [Garble.]

241:04:09 Worden: Normal.

241:04:10 Scott: Intercom T/R.

241:04:11 Worden: T/R.

241:04:12 Scott: [Garble.]

241:04:13 Scott: Off. [Long pause.]

241:04:53 Worden: Roger.

241:04:55 Scott: Houston, Endeavour. I guess the comm's acceptable to you down there on - with Al on VOX. Is that correct?

241:05:02 Henize: Roger. We're reading him loud and clear.

241:05:07 Scott: Roger. [Pause.]

241:05:14 Worden: Press Alarm, On; tone on.

241:05:17 Scott: [Garble] Off?

241:05:18 Worden: Off. [Long pause.]

241:05:38 Worden: On. [Long pause.]

241:06:13 Scott: Go ahead.

241:06:22 Worden: 900.

241:06:42 Scott: Roger.

241:06:43 Worden: Repress to Off. [Pause.]

241:06:51 Scott: Flashlight. Flashlight. Yes, got it. It's okay. It's off. Panel 600.1. Go.

241:07:16 Worden: Emergency O2 Valve, Closed.

241:07:20 Scott: Closed. [Long pause.]

241:07:49 Worden: No, I'm negative. [Garble] panel 8, front.

241:08:09 Worden: [Garble.] [Long pause.]

241:08:23 Worden: Just...

241:08:30 Henize: 15, we'd like to have Omni Charlie.

241:08:43 Scott: Roger. Omni Charlie.

[Comm break.]
241:09:52 Worden: Left to counterclockwise.

241:09:53 Scott: It's On.

241:09:57 Scott: It's on. [Long pause.]

241:10:42 Scott: Good.

[Very long comm break.]
241:20:55 Henize: 15, this is Houston. We'd like to get the High Gain Antenna up, if that's possible.

241:21:05 Scott: Roger. We'll do that.

241:21:08 Worden: Okay. Stand by. I'll get the High Gain. [Long pause.]

241:21:38 Worden: Okay. High gain?

241:21:40 Henize: Roger; and thank you.

241:21:41 Scott: You should have it. [Pause.]

241:21:50 Worden: Negative. Coming unstowed.

241:21:58 Worden: They're installed.

241:21:59 Unknown Speaker: [Garble.]

241:22:03 Worden: [Garble.]

241:22:05 Unknown Speaker: [Garble.]

241:22:09 Worden: It's attached.

241:22:09 Scott: Don OPS. Connect straps to adapter bracket.

241:22:13 Worden: In work. [Long pause.]

241:22:58 Worden: Okay. Wait. [Long pause.]

241:23:11 Worden: Wait a minute. Let's get the straps up. [Long pause.]

241:23:45 Worden: Okay.

241:23:47 Scott: Okay. Snap all the flaps.

241:24:01 Worden: Now, I'm on SCU whenever - Whenever you're ready.

[Comm break.]
241:25:16 Worden: Yes, I'm disconnected. [Long pause.]

241:25:31 Worden: All verified. Roger. Got you. [Pause.]

241:25:44 Worden: Okay.

241:25:55 Scott: You can leave them off. [Long pause.]

241:26:52 Scott: Down in the left-hand LEB, Jim. Bring it up with gloves and helmet, gloves inside. [Long pause.]

241:27:35 Scott: Cabin pressure, 5.2 [psi].

241:27:40 Worden: Yes.

[Comm break.]
241:29:42 Scott: Cabin pressure, 5.5.
[Comm break.]
Public Affairs Officer - "Distance now 172,176 nautical miles [318,869 km]. Velocity, 2,969 feet per second [905 m/s]."

241:31:53 Scott: Cabin pressure is approaching 6, and I'll crack the side hatch valve just a bit.

241:31:59 Irwin: Yep.

[Comm break.]

[Worden, from the 1971 Technical Debrief - "There was a lot of discussion about cracking the side hatch valve to maintain the cabin pressure during the EVA prep. That's particularly true when I was flowing through the umbilical. I thought that operation worked very well. I didn't see any problem at all with opening the side hatch valve just a little bit to relieve the cabin pressure."]

[Scott, from the 1971 Technical Debrief - "Except that it was easier for me to do it than it was for you."]

[Worden, from the 1971 Technical Debrief - "That's right."]

241:33:02 Scott: ...valve is on there now. Keep an eye on it.

241:33:08 Irwin: Roger. [Long pause.]

241:33:26 Worden: All locks.

241:33:28 Scott: Okay.

241:33:33 Worden: You guys do your integrity check before I put my helmet and gloves on. [Pause.]

241:33:49 Worden: In case I'd have something closed.

241:33:51 Scott: Cabin pressure, 5.4. [Long pause.]

241:34:13 Scott: Okay. O2 Flow High, pegged.

241:34:17 Irwin: Your light's on. [Pause.]

241:34:30 Worden: O2 Flow High, pegged. [Pause.]

[Comm break.]
Public Affairs Officer - "Heart rates in the 70's for all three crew men."

241:36:20 Scott: Vents.

241:36:22 Irwin: Vents all closed. [Long pause.]

Public Affairs Officer - "Heart rates now in the 60's with Dave Scott occasionally dropping down into the 50's."

241:37:19 Irwin: It's ready.

241:37:22 Worden: Side hatch valve coming on pull. [Long pause.]

241:37:56 Scott: Roger. That and my SCM. Okay? That'll hold steady.

[Comm break.]
241:39:53 Scott: ...pressure and temperature...

241:39:54 Worden: Yeah.

241:39:55 Scott: ...suit pressure reading?

241:39:58 Worden: Suit pressure's reading about - pound and a half above cabin. [Long pause.]

241:40:28 Worden: Cabin pressure's running about 5.9.

241:40:37 Scott: I'll pump it down a little bit. [Long pause.]

241:41:00 Worden: Jim. Stand by one. Get the cabin pressure down.

241:41:10 Scott: Okay. [garble] valve's, closed. SCS, closed. [Long pause.]

241:41:58 Scott: Houston, 15. The suit circuit looks pretty good up here. How does it look to you?

241:42:05 Henize: Roger, 15. It looks good to us down here.

241:42:11 Scott: Okay. Thank you. [Long pause.]

241:43:06 Irwin: SCU is done. 603 is On. Verified.

241:43:39 Worden: Okay. Let's get the helmet on first.

241:43:49 Irwin: Okay. Purge valve.

241:43:55 Worden: Got it. It's activated.

241:44:07 Irwin: Rog.

241:44:10 Scott: Pull the OPS down there, would you, Jim?

241:44:18 Worden: Hold it. Hold it up in front.

241:44:29 Worden: Okay. [Long pause.]

241:44:53 S/C: Can you [garble]?

[Comm break.]
Public Affairs Officer - "The back up Lunar Module Pilot, Jack Schmitt, is joining the group at the CapCom console."

241:46:20 Worden: Got it. [Long pause.]

241:46:55 Scott: Okay. Down and locked.

241:47:05 Scott: O2 coming off. [Long pause.]

241:47:40 Irwin: Locked. [Pause.]

241:47:48 Scott: Okay. I'll be pressurizing. [Long pause.]

241:48:16 Scott: [Garble.] [Long pause.]

241:48:51 Worden: [Garble] 3. [Long pause.]

241:49:10 Worden: Okay. [Long pause.]

241:49:28 Scott: Okay. Stable at 3.9.

241:49:36 Worden: Turn it off.

241:49:40 Irwin: [Garble] Verified, off.

241:49:43 Scott: Yes, it's okay.

241:50:05 Scott: 6. [Pause.]

241:50:14 Scott: Got it? Okay. It's off.

241:50:23 Irwin: Locked.

241:50:26 Scott: High. You've got the temp. Can you reach it? Hook that strap in for me, too, would you, please? No.

241:50:52 Henize: 15, Houston. We note that your cabin pressure's up to 6. You might consider dumping it down.

241:51:01 Scott: Roger, Houston. [Long pause.]

241:51:20 Irwin: Hooked.

241:51:38 Scott: Tell me when my temp [garble] anyone.

241:51:51 Irwin: Yeah. [Long pause.]

241:52:43 Scott: Okay. [Pause.]

241:52:50 Irwin: Reading 4.0.

241:52:55 Scott: Okay.

241:53:11 Worden: It's off. Warning tone's on.

[Comm break.]
241:54:18 Worden: Decay was about .1. It's on. O2 [garble] is on.

241:54:30 Scott: Reading 4 on stable.

241:54:32 Worden: Off. [Pause.]

241:54:43 Irwin: Reading 300. [Long pause.]

241:55:04 Scott: Okay, Houston; 15. We've got a good integrity check on the CMP, and standing by for a Go for depress from...

241:55:23 Worden: Dave, would you turn my [garble] valve, please.

241:55:31 Henize: We copy, 15. And you have a Go for depress.

[The main, or side hatch has a depressurisation valve built into it. It is operated by releasing a handle and winding the valve open. The crew are only 4 minutes behind their planned timeline.]
241:55:37 Scott: Roger.

241:55:38 Worden: Are they vertical now? [Pause.]

241:55:50 Worden: Other side too. Two of 'em.

241:55:52 Scott: Yeah. [Pause.]

241:56:02 Scott: Okay. You guys ready? Okay. Houston, 15. The side hatch dump valve is coming open.

241:56:14 Henize: 15, Houston copies. [Long pause.]

Public Affairs Officer - "Cabin pressure coming down."

241:56:47 Worden: Rog.

241:56:54 Scott: Want to stop there?

241:56:58 Worden: Well, okay. Think it's probably easier than I can. [Long pause.]

241:57:37 Scott: Reading 4.0. Go to 'em.

[Comm break.]
241:58:51 Scott: Yeah, it does. [Long pause.]

Public Affairs Officer - "Cabin is 1½ pounds per square inch."

241:59:21 Worden: Reading 3.8 on mine. [Long pause.]

Public Affairs Officer - "Half a pound cabin pressure now."

242:00:16 Worden: Roger. Fine. [Long pause.]

242:00:35 Scott: Okay.

[Comm break.]

[Flight Plan page 3-356.]

Public Affairs Officer - "Suit pressure, 4 pounds. Cabin, two tenths."

242:01:38 Worden: Yeah. It makes a difference. It's still flowing into the cabin.

242:01:42 Scott: How can you read me? You read me okay? Good.

242:01:42 Worden: You hear my VOX cut in and out? Good.

Public Affairs Officer - "Heart rates: Worden and Irwin in the 70's, Scott in the 60's."

[Mention of the crew's heart rates brings up the point that after the flight Dave had concerns as to whether Jim should have gone through the hatch for this EVA in light of the heart rhythm irregularities seen by the ground]

[Scott - "I think we should have had a discussion. We had a private loop. We could have had a comms loop discussion with the Flight Director and whoever, and they could have said, 'Jim's got a problem,' and we probably would have changed the EVA procedures.]

[Scott - "We could have switched - I just sat in the left couch. I didn't do anything. Jim didn't have a big job but he was standing in the hatch, helping Al. Suppose he had had a heart attack and died? Would have been a bad day. Would have been better to put Jim in the left couch and let him just relax, and let me do his job, which wasn't a big deal. But nevertheless, I'd have switched it."]

[Woods - "Had something happened, you would have been in a more secure position."]

[Scott - "Yeah. I mean if I had known Jim had a problem, then I would have said, 'Let's switch roles for Al's EVA and you just sit there in the couch and watch the world go by.'"]

[Harland - "Well you'd done a head-out-of-the-hatch on [Apollo] 9 so you know what's involved there."]

[Scott - "Yeah. I'd understand the hatch. Yeah. At the very least, we'd have had a nice discussion with the Flight Director, 'nice' being full disclosure of the situation and full discussion of what's the best thing to do."]

242:02:15 Scott: Yeah. Okay. You ready?

242:02:28 Scott: I suspect that SCU is forward enough to keep it there. [Long pause.]

242:03:01 Worden: It'll hold. Now. [Pause.]

242:03:12 Worden: It's released. It's in the yellow?

242:03:18 Worden: No. We've missed it.

242:03:20 Scott: Yeah. I can't see it. Jim, can you see the indicator?

242:03:23 Irwin: I can't either, can you?

242:03:27 Scott: Stand by one.

242:03:30 Worden: Roger. [Garble.]

242:03:39 Scott: Houston, 15. We're getting ready to open the hatch. How does everything look to you down there?

242:03:49 Henize: Roger, Al. Everything's looking good to us here.

242:03:53 Worden: ...out, Dave.

242:03:56 Scott: Okay? Unlatch. Unlatch. Ready? Rog.

242:04:19 Worden: No.

242:04:23 Henize: 15, Houston. We don't see the TV camera on yet.

242:04:25 Worden: The hatch is open.

242:04:29 Scott: Huh. Oh, we haven't got it out yet. We'll have it out there in a minute. It should be on though.

[Al's EVA has been described as the first interplanetary spacewalk, in an age that placed much prestige on space "firsts". Apart from the three Apollo EVAs to retrieve SIM bay film cassettes, every other EVA from a spacecraft in freefall has taken place in low Earth orbit, never more than about 600 kilometres away from the home planet. This was still true at the time of writing thirty years after the event.]

[Scott, from the 1971 Technical Debrief - "Hatch opening occurred about 5 minutes after the planned hatch opening. The integrity checks went very well. The procedures played just exactly as they were laid out in the checklist and just like we've seen them in the chamber. I'm glad we ran those chamber runs because that helped us, Jim and I, to understand what you were doing with your equipment."]

[Worden, from the 1971 Technical Debrief - "I think so, too. We were all well prepared for the EVA."]

242:04:33 Worden: Okay. I got the latch - the handle and latch.

242:04:39 Scott: Roger. Roger.

242:04:46 Worden: Okay. [Long pause.]

242:05:09 Worden: Okay. [Garbled.]

242:05:16 Worden: [Garble] zero. Clips.

242:05:32 Worden: Jettison bag is gone. And jettison bag number 2.

242:05:50 Worden: Okay. [Long pause.]

[Worden, from the 1971 Technical Debrief - "After getting the hatch open, the first thing I did was take the TV and the DAC and mount them on the bracket in the hatch. The hatch didn't get fully opened the first time. When I got part way out, I guess you opened the hatch the rest of the way so that the camera was pointing down along the SIM bay. I just went outside the hatch, grabbed the first handrail, and positioned myself just outside the hatch until Jim got in the hatch to observe and to watch the umbilical."]

[Later in the Technical Debrief, when the crew discuss simulations, Al discusses the training he did in the WIF (Water Immersion Facility). This technique, where an EVA crewmember dons a spacesuit, modified for use underwater and weighted to give neutral buoyancy, to give an impression of how the body moves in a zero-g environment has become the preferred method of training for the lengthy EVAs performed almost routinely in low Earth orbit.]

[Worden, from the 1971 Technical Debrief - "I thought the training program for the EVA was just right. There wasn't too much. I thought there was an adequate amount of training. The sessions in the WIF could have been reduced somewhat because the sensation of neutral buoyancy is sufficiently removed from zero-g that with too much training in the WIF, it almost turns out to be negative training. The operation is so much more difficult in the WIF than it is in flight or in the zero-g airplane that fewer sessions in the WIF would have been in order. Maybe one or two sessions in the WIF, instead of a large number of them, would be perfectly adequate. The zero-g airplane was invaluable. The one-g trainer going through the prep and the post was completely adequate. I thought that particular training program was outstanding."]

Public Affairs Officer - "We're getting a picture now."

242:06:16 Scott: Okay, Houston. You should be getting a picture about now.

242:06:21 Henize: Roger, 15. We're getting a signal. [Long pause.]

242:07:04 Worden: Okay. [Pause.]

242:07:12 Worden: Okay. Fine. First thing is that the map - the Mapping Camera is all the way out.

242:07:27 Scott: Okay. [Pause.]

242:07:34 Scott: Okay. [Long pause.]

242:07:52 Henize: 15, this is Houston. We're getting a clear picture now, but the aiming of the TV camera is poor. Is it possible to open the hatch wider?

242:08:10 Scott: Yeah, that's what - we're - we're looking at that, too. Stand by one, and we'll do that. [Pause.]

242:08:44 Worden: Yes, I can see the TV is pointed right at the Command Module there. Right at the interface.

Real Video file (142K)

[This Real Video file is taken from NASA's post-mission documentary on the mission.]
242:08:51 Henize: That's affirm.

242:08:57 Scott: Push it back a little there, Jim. Okay.

242:09:11 Henize: That's excellent.

242:09:13 Scott: You should have a picture at a man in space.

242:09:15 Henize: Very good. [Pause.]

242:09:20 Worden: Okay. You ready, Jim? I'll work my way down. Okay, it's reading 4. Okay. [Long pause.]

Public Affairs Officer - "Distance 171,000 [nautical] miles [316,691 km]."

Diagram showing how Worden maneuvers along the SM

[This illustration outlines how Al is to progress along from the CM hatch to the foot restraints in the SIM bay. Having exited the CM (1), he uses handholds mounted all along the side of the Service Module (2) until he is over the bay (3). Further handholds surrounding the SIM bay allow him to rotate (4) until his feet are in the correct position to engage them in the foot restraint (5), giving him full access to the bay.]

[Worden, from the 1971 Technical Debrief - "I went hand-over-hand down the SIM bay and to the left around the Mapping Camera. I just floated myself over the Mapping Camera instead of going around it down into the SIM bay. I put my feet in the foot restraints and just stood there for a minute, resting and looking at the SIM bay, and waiting for Jim to get himself positioned in the hatch."]

242:09:50 Scott: We'll have your picture back in a minute, Houston. We're turning on the 16-millimeter.

242:09:58 Henize: We copy.

242:09:59 Scott: Yes. [Long pause.]

242:10:07 Scott: Okay. [Long pause.]

242:10:40 Worden: Okay. I'm in the front restraint.

242:10:45 Henize: Yes, that's good work up there, Al. [Long pause.]

242:11:37 Worden: Okay, the Pan Camera cassette is tethered. There's the pip pin.

242:12:32 Scott: Good.

[Comm break.]

[Worden, from the 1971 Technical Debrief - "The Pan Camera went just as I had anticipated it would go. I pulled the metallic cover off the Pan Camera and released it. Then, I pulled the fabric cover off. The force that it took to pull both of those covers off was just as I had expected and remembered from preflight. It was the same operation. I pulled the pin on the Pan Camera cassette, tethered myself to it, and pulled the release handle. It came out even easier than I had expected. The mass of the Pan Camera cassette was a little bit more than I had expected, but it was no problem handling it. I just very carefully drifted it back towards the hatch, keeping my hand on the handle and maneuvering myself back. I did release it at one time, because I had to use both hands to maneuver myself over the Mapping Camera. But I didn't release it clear to the end of the tether. I just let go for a minute, repositioned myself, and then grabbed it with the handle again. I thought that went very smoothly."]

Public Affairs Officer - "Worden's heart rate about 130 now."

Public Affairs Officer - "Irwin's heart rate 116, Scott's 71. There's the film cassette."

242:13:43 Scott: Get it inside there, if you can, Jim. Get it inside. [Long pause.]

242:14:26 Irwin: Okay.

242:14:30 Worden: Rog. Would you like to exchange - would you like to get hold of it? [Laughter.]

242:14:42 Worden: That's the Pan Camera [cassette], right. Okay, Houston. The Pan Camera is safely inside. Over.

[Worden, from the 1971 Technical Debrief - "The transfer back through the hatch went just as we'd done before, too. I handed the Pan Camera cassette back in through the hatch. You tethered it and then released my tether. That was pretty much as we'd done before; no problems there."]

[Scott, from the 1971 Technical Debrief - "I put it down in the LEB and it stayed. I left it on the tether and it never got in your way. No problem."]

242:14:42 Scott: Jim, hold this.

242:14:53 Henize: Beautiful job, Al baby. Remember - remember, there is no hurry up there at all.

242:15:02 Worden: Roger, Karl. I'm enjoying it. [Long pause.]

Public Affairs Officer - "Going back for the Mapping Camera cassette now."

242:15:35 Worden: Okay, Houston. Rest break. We'll take a look at the V over H sensor.

242:15:41 Henize: Very good.

242:15:48 Worden: Uh, hum, I see nothing on the V over H sensor. There's no back - black paint missing. There's nothing obscuring the field of view. The glass is not cracked.

242:16:13 Worden: The shield is not obstructing the field of view. There's nothing in the way, Karl.

242:16:21 Henize: We...

242:16:22 Worden: It's perfectly clear.

242:16:23 Henize: We copy your report, Al. Thank you.

242:16:29 Worden: Okay. And as I look around, the Mass Spec. is - oh, it looks like about - not quite in - the cover. It looks like maybe it's the cover that's jammed. Yes, in fact, it is the cover that's jammed. See?

242:16:57 Henize: Roger, Al. We copy. That was most unexpected news.

242:16:59 Worden: No, I can't tell from here. I can't really - I can't really tell from here, Karl, whether it's the cover or not. I thought the cover was jammed. One corner of the cover is overlapping a - side section of insulation which I wasn't expecting it to. But it doesn't seem to be - it doesn't put any force on it - on the Mass Spec. If I could get around and take a look at it. The Mass Spec. is in the guide pins, and the Mass Spec looks like as it is fully retracted. The Mass Spec. is fully retracted, Karl.

242:17:57 Henize: Roger, Al. We're reading you loud and clear.

242:17:59 Worden: Any - any diffi - any difficulties with the talkback has to be associated with that cover, because the cover is not closed. How far through the slot should the guide pin come on the - on the reel?

242:18:18 Henize: Stand by, Al.

242:18:21 Worden: Okay. 'Cause I can see a guide pin coming through. You do that, and I'll get the map - Mapping Camera.

[Worden, from the 1971 Technical Debrief - "The Inconel cover on the Mass Spectrometer was cocked about 30 degrees from the closed position. I reached over and grabbed the cover and moved it a little bit. It's a fairly flimsy cover, but I wanted to see if it was jammed against anything. One corner seemed to be hung up. I released it, but the cover stayed where it was. I really couldn't close it. Then, I looked down inside the Mass Spec. itself and noticed that the guidepins were through the guide slots in the experiment itself, indicating that it had at least positioned itself on the base of the boom itself. I wasn't sure at the time. That's something I hadn't looked at preflight. I wasn't sure just how far those guidepins should come through the slots to indicate that the Mass Spectrometer was fully retracted. So I called down to the ground and said that the tip of the guidepins were just through the guideslot. They called back and said that it wasn't fully retracted then, because the guidepins should be through the slots far enough so that the cylindrical part of the guidepin could be seen. So, that indicated to me that the Mass Spectrometer wasn't fully retracted. That was all I could see on it. I couldn't see around the Mass Spectrometer. I couldn't see down into the SIM bay at that point because the cover was obscuring the view."]
Public Affairs Officer - "Worden's heart rate 97 now."

242:19:39 Worden: Okay, Jim. I'm ready to bring the other one back.

242:20:03 Henize: Hey, Al. It looks like you're running a pass up there. That's beautiful. [Long pause.]

Public Affairs Officer - "And there was the Mapping Camera cassette."

242:20:27 Worden: Okay. [Long pause.]

[Worden, from the 1971 Technical Debrief - "I pulled the cover off the Mapping Camera, I noticed that that particular cover was a little more difficult to release than I had anticipated. That particular cover is set under a flange on either side. It's held down by some pins at the release end of the cover. I had to twist it a little bit and pull it a lot harder than I had anticipated to release it from the flanges on the side. But, it did come off all right; there was no problem. The fabric cover underneath got hung up on one corner. The fabric has a rubber slot that it fits into around the edges, and it's almost an airtight seal. That rubber-slotted flange hung up in one corner, and I had to pull it three or four times before I got it released. After that, everything was just as I had anticipated."]

["I tethered the Mapping Camera cassette, released it, and it was a very easy operation after that. I brought it back into the hatch, as we had practised preflight."]

242:21:10 Worden: Jim, you look absolutely fantastic against that Moon back there. That is really a most unbelievable, remarkable thing.

242:21:25 Scott: Okay, Houston. The Mapping Camera cassette is inside.

242:21:30 Henize: We copy. [Pause.]

242:21:42 Worden: Houston, is there anything else you want me to check in the SIM bay before we go back in?

242:21:52 Henize: Al, we'd be...

242:21:53 Worden: Is there anything on the Mapping Camera I can check?

242:21:55 Henize: Al, we'd be pleased to have any general comments you had about the SIM bay experiments, otherwise than what we specifically asked you. Did everything look in order?

242:22:05 Worden: Okay. Well, everything looked good, as far as I could tell, all except for the cover on the Mass Spec., and the fact that the Mapping Camera is up. Maybe I could make another quick check back here and see if I can see anything on the Mapping Camera.

242:22:23 Henize: Rog. [Long pause.]

[Worden, from the 1971 Technical Debrief - "I think the concern at the time was that the Laser Altimeter/Mapping Camera contamination cover was binding against the side - forcing it to stay in the Extend position. I went back out and looked, and there was about three-fourths of an inch to maybe 1 inch clearance between the cover and the Mapping Camera itself. From that, I concluded that the cover hadn't anything to do with it. I looked underneath the Mapping Camera, and I looked around all of the edges to see if there was something binding, maybe something that had lodged alongside the Mapping Camera. Everything looked clean to me. There was nothing that was impinging on the Mapping Camera at all. The stellar shield was still out, but of course, it would be with the camera extended. At that point, it was maybe 12 to 15 inches away from the SIM bay mold line. So, there was nothing I could tell from there that would shed any light on why the Mapping Camera did not retract."]
242:23:11 Worden: Okay. You ready, you guys?

242:23:16 Scott: All right. [Long pause.]

Public Affairs Officer - "Worden's heart rate 85 now."

242:23:40 Worden: Oh, just a second. I've got get the mask and get the TV.

242:23:54 Worden: Okay. TV coming in. Got it, Dave? Okay.

242:24:03 Scott: Okay, take your time.

242:24:05 Worden: I - I'm doing fine. [Long pause.]

242:24:20 Worden: Okay. [Pause.]

242:24:33 Worden: Hung up - on something. [Long pause.]

242:24:58 Scott: Ah, yes, it's about the same place it was when we opened the hatch. [Pause.]

242:25:15 Worden: Okay. Hatch is locked.

[Worden, from the 1971 Technical Debrief - "I went back in the hatch, pulled the quick release on the TV camera bracket, which we had decided to do preflight. Rather than releasing the handle itself, we pulled the Marmon clamp, releasing the pole. I sent the pole in the hatch, backed into the hatch myself, and pulled the hatch closed. I thought that went very easy. It took hardly any force at all to close the hatch. It operated very smoothly and very freely. I pulled it right down to the point where it was closed. A couple of pumps on the handle, and the latches were over and off. It was very simple operation."]
242:25:21 Scott: Neutral. Gear box is in latch.

242:25:35 Worden: Can you do it, Dave? Okay.

242:25:40 Henize: 15, Houston. You can turn off the TV anytime you like.

242:25:47 Scott: Let us get depr - pressurized first, Karl.

242:25:52 Irwin: Okay. [Pause.]

[Worden, from the 1971 Technical Debrief - "Once we got the side hatch open, from that point to the time we closed the hatch, the whole operation went almost exactly as it had in preflight training, both in the zero-g airplane and the Water Immersion Facility. I don't recall anything during the EVA that I thought was off-nominal. As a matter of fact, it was so much like preflight, that I really had no anxieties about the EVA at all. The whole thing went just as smooth as it could."]

["It was just as we practised. That's the key to the whole thing - good solid practice before flight. Be well prepared for what's going to be out there and for the kind of body motions that are required to get back into the SIM bay and into the foot restraints."]

["In true zero-g it was really much easier than it had been even in the zero-g airplane. I think there's some rotation that you get in the zero-g airplane that does effect your motions a little bit. True zero-g is just much easier. If you can do it in a zero-g airplane and in the Water Immersion Facility, in flight it is easy."]

242:25:59 Scott: Can you get it there?

242:26:00 Worden: Okay.

242:26:01 Scott: Very good. [Pause.]

242:26:10 Worden: Okay. [Long pause.]

242:26:41 Irwin: Tell me when to close it. That's it.

242:26:47 Worden: [Garbled.] Take it down here before it's too - okay, okay.

242:27:09 Scott: Okay?

Public Affairs Officer - "Cabin pressure coming up now."

242:27:11 Worden: I said, I wish I were back outside. It's hell in here. Okay.

242:27:18 Irwin: Closed.

242:27:24 Worden: I can't. No. Yeah. That's okay, Jim.

242:27:43 Irwin: How's that? There we go. Now we should get our positions straight. You see it now, Dave? Okay. Make sure we got a good seal.

242:28:08 Irwin (onboard): Cool it here for a minute.

242:28:22 Scott: Okay, Houston; 15. It looks like we got a good seal. How's it look down there?

242:28:38 Henize: 15, Houston. Your seal looks good to us.

242:28:44 Scott: Okay, thank you. Is 601 open?

Scott (onboard): 601, Repress O2, Open.

242:28:52 Irwin [Worden in onboard transcript]: It's open.

242:28:53 Scott (onboard): Monitor Repress O2 indicator to zero.

242:29:03 Irwin [Worden in onboard transcript]: and it looks zero now, Dave?

242:29:04 Scott (onboard): Okay. So, you let your umbilical flow bring every - the cabin up to 3.

242:29:10 Scott [Worden in onboard transcript]: Rog. [Long pause.]

Public Affairs Officer - "Cabin pressure 2 pounds."

242:29:11 Scott (onboard): That's very nicely done. That's about - 22 minutes. Which is just about what we figured. You went back and looked at all that stuff. So that's just about right.

242:29:52 Scott (onboard): It's fun out there, isn't it?

242:29:54 Worden (onboard) [Scott in air/ground transcript]: Mm-hmm. Should have stayed longer.

[Comm break.]

[Al gets a question along the same lines during the inflight press conference tomorrow. When asked why he came in so soon, he answered that he came in when the job was done. The following interview with Dave, conducted in 2004, was before I discovered it was Worden who said he should have stayed out longer.]

[Woods - "Al seemed to spend an awful short time outside. You told him you should have stayed there longer. He was all for get out there, do the job, get back in. That seems a bit of a shame from his point of view."]

[O'Brien - "I would imagine that you would have a little bit of free time, but this wasn't time critical. You were plugged into the CSM. You weren't in a rush."]

[Scott - "Weren't in a rush, but on the other hand, the purpose was to get the film and get back in. I think Al did the right thing. Came back in. I mean, it'd be nice to stay out and float around and look around but, why? So if you stay out and float around and look around and then something goes wrong during that period, then you say, 'Why did I do that?' So I think what you do is you do your job and you get back in and close the hatch and say, 'Gee, that was wonderful. I had a great time. I did my job.' I think to float around out there is exposing yourself to an unnecessary risk. It's low risk, but on the other hand, it's high risk. So what if that last minute is a time you popped a leak for some reason? Eh? So shoot, get the job over. As sort of an analogy, we used to fly airplanes in bad weather. Rule was always; go to your destination, finish your mission and then play around because if you got to get down, you got fuel."]

[Woods - "You say to him here, 'You should have stayed longer.'"]

[Scott - "He got it done very quickly and very efficiently and came back in and the comment is, 'Geeze, you were having a good time. Why didn't you stay a while?' But I didn't really mean that. I meant it in a positive way. 'You should have stayed out there and stayed longer. You were doing really great, terrific.' But if you look at the seriousness of it, he did exactly right. He got his job done and he got in."]

[Woods - "On both of your Apollo flights, somebody went out through the main hatch of the Command Module. That's an impressive piece of engineering, an outgoing door that holds against 5 or 6 psi. After the Apollo 1 tragedy, were you involved at all in the redesign of that?"]

[Scott - "Yeah. They had all these working groups to fix all the problems. Not just the fire-related problems. All the problems kind of stuff. And I was on the working group with the probe and drogue and with the hatch and with the EMS and something else. But, yeah, I was pretty much in the middle. And in the hatch thing, they brought McDonnell Douglas guys in to really help them with that."]

[O'Brien - "Really?"]

[Scott - "Yeah, well, Gemini had an outward-opening hatch, right? They brought in the MacDac guys to help the Rockwell guys redesign the hatch."]

[Woods - "And as it happened, you were the first person to really test it on Apollo 9."]

[Scott - "Ah, but it worked. It was really a good hatch."]

Public Affairs Officer - "The cabin's at 2.3 now. They'll bring it up to 3 pounds using the spacecraft system. Then they will dump the OPS, the emergency oxygen backpack that Al Worden carried with him. They'll dump that at 3 pounds to bring the cabin pressure on up."

242:29:57 Scott (onboard): (Laughter) You done good. You made a lot of people back there very happy.

242:30:04 Worden (onboard): Roll over and let me take another look again.

242:30:ll Scott (onboard): Well, I'll tell you what, your - your left arm or something's covering up the light over there.

242:30:16 Worden (onboard): The OPS is, I guess.

242:30:19 Scott (onboard): Really bad lights in here.

242:30:20 Worden (onboard): Okay, there. I can see it now.

242:30:23 Scott (onboard): We're at 2.4, about. So we'll just let your flow bring it up to 3. Gee, I had a great view on the TV. Did you turn the TV off, Jim?

242:30:39 Irwin (onboard): No, I didn't...

242:30:40 Worden (onboard): I'll turn it off.

242:30:41 Scott (onboard): Can you reach it?

242:30:42 Worden (onboard): Yes. There. Thought I turned it off.

242:30:53 Scott (onboard): Can you reach the Scientific TV switch? The S-band TV switch, Jim?

242:30:59 Irwin (onboard): No, not yet, Dave.

242:31:01 Scott (onboard): Okay. Maybe I can. No.

242:31:06 Irwin (onboard): I don't think there's any rush on that, is it?

242:31:08 Scott (onboard): No.

242:33:00 Henize: 15 - 15, Houston. As long as we have the TV camera on, go - go to Average, and we should get a better picture down here.

242:33:11 Scott: Well, it's just down in the LEB sort of stowed away, but we'll do that.

242:33:26 Scott: We're just not in a position to get the panel 3 switch right now.

242:33:31 Henize: We - we copy, and that's fine. [Pause.]

242:33:50 Scott: You may have something on your picture, now. I'll check.

[Long comm break.]
Public Affairs Officer - "That's the hatch window in the background there."

242:37:18 Worden: Cabin pressure rate is coming up.

242:37:22 Irwin: They're out of lockup.

[Comm break.]
Public Affairs Officer - "Cabin pressure is up to 4½ pounds per square inch and the consensus in the control center is that that was reflection of lights in the cabin that you saw in the hatch window. Heart rates far Worden and Irwin now in the low 70's, for Dave Scott, high 50's."

Public Affairs Officer - "The cabin is up to 5 pounds per square inch."

Public Affairs Officer - "Apollo 15 distance from Earth now 170,172 nautical miles [318,158 km]. Velocity 3,016 feet per second [919 m/s]."

242:40:37 Irwin [Worden in onboard transcript]: I'll get it. [Long pause.]

242:40:38 Scott (onboard): Here, give me it first, Al.

242:41:02 Scott: Got it.

242:41:03 Worden: PGA pressure. [Long pause.]

242:41:23 Worden: [Garbled.]

242:41:25 Scott: Yes.

242:41:26 Worden: [Garbled.]

Public Affairs Officer - "This is Apollo Control. The EVA clock here in control center recorded 39 minutes, 56 seconds [total EVA time]."

242:41:31 Scott: On.

242:41:35 Scott: Why don't you do it so I don't get my gloves dirty. Get my helmet. Get that stuff off and leave them.

[Comm break.]
Public Affairs Officer - "And that time is about - from about midway during depressurization to midway in repressurization."
[EVA times are measured from the time cabin pressure indicates less than 3.5 psi until it rises above this figure again. Although nearly 40 minutes were clocked for the EVA, the hatch was only open for twenty of those, though the Flight Plan had 53 minutes set aside for it.]
242:45:59 Henize: 15, Houston. We see your cabin at 6.1 [psi]. You might want to keep a close eye on that.

242:46:09 Scott: Okay; we'll do that. Thank you.

[Long comm break.]

[The crew are raising the cabin pressure by bleeding the contents of the OPS oxygen bottle. The Flight Plan calls for them to do this until the bottle is depleted. However, on this occasion, this is providing too much air. With the cabin repressurised, they can doff their suits and begin configuring the cabin for the rest of the journey home.]

Public Affairs Officer - "This is Apollo Control. We have some unofficial times on some of these EVA events. The Go for depressurization was given at 241 hours, 55 minutes, 33 seconds. Depressurization started at 241:56:12; hatch open, 242:05:33; Worden going out the hatch, 242:07:29; hatch coming closed, 242:25:20; and the pressure - cabin pressure starting to come back up at 242:27:25."

242:52:38 Scott: Houston, 15. We're prepared to maneuver to the thermal attitude a little early if you'd like us to go over there.

[This is an attitude to mitigate the effects of solar heating on one side of the spacecraft and the chill of space on the other. However, the version of the Flight Plan used in the compilation of this journal does not show a change in attitude until 245:30, when there is a further period of x-ray astronomy using the SIM bay's X-ray Spectrometer.]
242:52:47 Henize: 15, this is Houston. That would be fine with us.

242:52:53 Scott: Roger.

[Long comm break.]
242:58:10 Henize: 15, Houston. We'd like to have Auto on the High Gain [Antenna] and go from Reacq to Auto quickly.

242:58:18 Scott: Roger. Going Auto. Over.

[Very long comm break.]

[If they were to place the HGA's Track switch from Reacq to Auto slowly, it would pass through the Manual position, whereupon it would begin to slew to the positions set on the HGA's position dials and go off lock. Since the HGA is already correctly pointed, they want to keep that position, perhaps to keep a solid telemetry record.]

[Flight Plan page 3-357.]

Public Affairs Officer - "This is Apollo Control at 243 hours, 02 minutes. Apollo 15 now 169,526 nautical miles [313,962 km] from Earth. Velocity: 3,031 feet per second [924 m/s]. Weight: 26,509 pounds [12,024 kg]."

243:25:57 Henize: 15, this is Houston.

243:26:07 Scott: Go ahead, Houston; 15.

243:26:10 Henize: After some discussion down here, we'd like to disable your jets A2 - Alpha 2 and Bravo 1, mainly because the Mapping Camera's still out and our concern is that the plume will be deflected down into the SIM bay and possibly damage some of our electrical wiring or some of the - the N2 plumbing, which may give us other problems.

243:26:36 Scott: Roger. That sounds like a good idea. If there's any other particular configuration you want, just let us know.

243:26:42 Henize: Roger.

243:26:47 Scott: And A2 and Bravo 1 are disabled.

243:26:51 Henize: Thank you.

[Very long comm break.]
Public Affairs Officer - "This is Apollo Control at 243 hours, 58 minutes. The crew of Apollo 15 busy stowing equipment, reconfiguring the cabin. Very quiet time as far as communications are concerned. Apollo 15 now 167,882 nautical miles [310,917 km] from Earth. Velocity: 3,070 feet per second [936 m/s]. And the clock showing 51 hours, 12 minutes to landing."
[Flight Plan page 3-358.]
244:01:39 Scott: Houston, 15.

244:01:42 Henize: 15, go ahead.

244:01:47 Scott: Rog. The OPS pressure is 2,000 [psi] and we'll be off comm for about 5 or 10 minutes here while we reconfigure the suits and everything.

[Since the OPS was not bled to depletion, Dave reports the source pressure reading on the bottle instead. Before use, its pressure gauge read 5,800 psi (40,000 kPa) and is now reading 2,000 psi (14,000 kPa).]

[Other items to be completed are a dump of the excess water produced by the spacecraft's fuel cells and a purge of those cells with oxygen. There is an additional item which is to charge battery B, delayed from before the EVA but the crew will delay all these items a little longer. The spacecraft's batteries are regularly charged during quiet periods to replenish them after any discharge that might have occurred during heavy usage in the meantime.]

244:01:57 Henize: We copy.

244:01:59 Scott: Go.

[Very long comm break.]
244:34:13 Henize: 15, this is Houston. [No answer.]

244:34:31 Henize: 15, this is Houston. How do you read? [No answer.]

[Comm break.]
Public Affairs Officer - "This is Apollo Control at 244 hours, 35 minutes. The Apollo 15 crew apparently still off the communications system as they are reconfiguring their cabin. We're showing cabin pressure holding at 5.7 pounds per square inch. Temperature, 68 degrees."

244:36:43 Henize: Apollo 15, this is Houston. How do you read? [No answer.]

[Comm break.]
244:38:25 Henize: Apollo 15, this is Houston. How do you read? [No answer.]
[Comm break.]
244:39:41 Scott: Houston, Apollo 15. We'll start to charge on battery B now, if you're ready.

244:39:46 Henize: Roger, 15. We're ready for the battery charge; and, while we're about it, the experimenters are getting a little fidgety about the waste water dump because that will impact their Mass Spectrograph work, so we would like to get the dump and the O2 fuel cell purge started also.

244:40:04 Scott: Roger. We'll get on it right away. [Long pause.]

244:40:56 Henize: And, 15, whenever Al has a couple of minutes, we have a few questions about the SIM bay that we'd like to debrief on.

244:41:09 Scott: Okay, give - give him another 15 to 20 minutes here.

244:41:13 Henize: Rog.

[Very long comm break.]

[Flight Plan page 3-359.]

Public Affairs Officer - "This is Apollo Control at 245 hours. Apollo 15 picking up velocity, getting closer to home each second. Endeavour is now 166,043 nautical miles [307,511 km] from Earth. Velocity: 3,113 feet per second [949 m/s]."

245:04:19 Henize: 15, this is Houston.

245:04:25 Scott: Houston, 15. Go ahead.

245:04:28 Henize: We need to make a small change in the Flight Plan, because there's a need now to turn the X-ray experiment on. If you'll go down to that group of steps at 245:30, we'd like to do four of them. We'd like to get the "Data Systems - On - switch to On." We'd like to "Disable the jets." We'd like to get "S-band AUX, TV to Science."

245:04:48 Worden: Hey, stand by one.

245:04:50 Henize: Rog. [Long pause.]

245:05:12 Worden: Okay. Go ahead.

245:05:14 Henize: Roger. Four of those steps down at 245:30 we want to do right away, if possible. We want to get the "S-band AUX, TV to Science." We want the "Data System On switch to On." We want to "Disable all jets except -" and we want "X-ray Experiment, On."

245:05:39 Worden: Okay. Understand at 45:30 - 245:30, you want "S-band AUX, TV to Science, Data Systems On to On, disable all jets, and X-ray Experiment, On" immediately.

245:05:54 Henize: That's correct.

[Very long comm break.]
245:13:15 Worden (onboard): We need the repress time on the cabin. ...

245:13:18 Scott (onboard): Yes.

245:13:53 Scott (onboard): Ten days and 5 hours we've been gone, Jim.

245:13:59 Worden (onboard): Long time. We beat your old record.

245:14:00 Scott (onboard): By 3 minutes.

245:14:03 Worden (onboard): Sure does. Went farther from home, too.

245:14:10 Scott (onboard): That's great.

245:14:11 Worden (onboard): Didn't go as far.

245:14:13 Scott (onboard): Let's not count the miles.

245:14:15 Irwin (onboard): ...

245:14:16 Scott (onboard): Huh?

245:14:17 Worden (onboard): Didn't go as far, but went farther.

245:14:19 Irwin (onboard): Yes, coming back.

245:14:22 Scott (onboard): And a lot more fun, too.

245:14:30 Worden (onboard): A lot more to it.

245:14:35 Scott (onboard): Big Dipper, do you know, on 9, we could have missed any one thing and pressed on.

245:14:41 Irwin (onboard): Yes.

245:14:42 Scott (onboard): Here, it's a lot different; you can't miss anything and press on.

245:14:46 Worden (onboard): Well, it looks like we can't miss anything.

245:14:49 Scott (onboard): Very different. Very different.

245:15:13 Scott (onboard): This is sort of an all-or-nothing kind of operation, you know it?

245:15:18 Worden (onboard): Yes, it really is, you know. It's really all your eggs in one basket, boy. I got to thinking about that after you guys left for your descent. Once you start that descent, man, that - that's it...

245:15:40 Irwin (onboard): We're all hanging out.

245:15:41 Worden (onboard): We're there. That's right. It's all hanging out from there on.

245:15:46 Irwin (onboard): ...

245:15:54 Worden (onboard): It would be better for ... to put pills in all the food drawers.

245:15:59 Scott (onboard): (Laughter) For sure.

245:16:02 Worden (onboard): Make him ...

245:16:03 Scott (onboard): Let's put them away somewhere.

245:16:07 Worden (onboard): Where will I put them? It's the last time I'm saying it, but you better not lose your pills.

245:16:13 Scott (onboard): You didn't see them in your TSB, did you, Jim?

245:16:16 Irwin (onboard): What?

245:16:17 Scott (onboard): You didn't see the pills in your TSB when you cleaned out, did you?

245:16:20 Irwin (onboard): No ....

245:16:31 Scott (onboard): Ohh, what did I do with it?

245:16:33 Irwin (onboard): ...

245:16:34 Worden (onboard): It's almost back to normal times.

245:16:38 Scott (onboard): Where did you see them?

245:16:40 Irwin (onboard): Down in U-1.

245:16:45 Worden (onboard): Do you really know what ...?

245:16:48 Irwin (onboard): ...

245:16:49 Worden (onboard): ...

245:16:49 Henize: Apollo 15, this is Houston. We're having some ground problems in communications networks, and we'd like to have a comm check.

245:16:57 Scott (onboard): Oh! Did you notice anything loose?

245:17:03 Worden (onboard): Well, I thought I saw - Well, I saw a...

245:17:08 Scott (onboard): Hey, do you guys ... get some orange juice? ... Let's enjoy it - let's enjoy it while we can.

245:17:16 Worden (onboard): ...

245:17:17 Scott (onboard): Except for bad stuff, we can always put up with it for 1 more day.

245:17:20 Worden (onboard): Yes, that's right. Well - Hey, let's - ... will be our last meal. We have three meals below and breakfast ... 1 day.

245:17:28 Scott (onboard): And a long way to go.

245:17:29 Worden (onboard): Oh, hush.

245:17:29 Henize: Apollo 15, this is Houston. How do you read?

245:17:39 Worden: Hello, Houston; this is 15. Loud and clear, and I got your first message, Karl. I'm sorry.

245:17:44 Henize: Hi, Al. Yeah, we've got some sort of problem on ground circuits here. Just wanted to make sure we were in contact with you.

245:17:54 Worden: No, we're here.

245:17:55 Henize: Roger; very good. [Long pause.]

245:18:46 SC (onboard): (Cough)

245:18:53 Henize: Al, we have some questions for you on the SIM bay experiments, whenever you have some time to answer them.

245:18:58 Worden (onboard): Oh, yes. That's right. That's great.

245:19:04 Worden: Okay, Karl. Tell you what, I'll give you a call back in about 10 minutes when I'm ready.

245:19:10 Henize: Very good.

[Very long comm break.]
245:19:14 Worden (onboard): No, he's got some questions on the SIM bay.

245:19:37 Scott (onboard): SIM bay looks pretty good.

245:19:42 Irwin (onboard): What'd ...?

245:19:43 Worden (onboard): I'm coming. I'm coming, Jim. ...

245:19:46 Irwin (onboard): Yes, I can see through on the handles.

245:19:55 Worden (onboard): I didn't even see any scorching or any burning or anything down there.

245:19:59 Irwin (onboard): ...

245:20:02 Worden (onboard): The covering on the - on the service module, if it hadn't been covered, boy, that would have been burned and scarred and scorched and everything else.

245:20:10 Scott (onboard): Yes. That's right.

245:20:11 Irwin (onboard): Yes. Yes. Excuse me 1 second, will you?

245:22:11 Worden (onboard): Excuse me, Jim. Let me get out of your way here.

245:22:27 Scott (onboard): ...

245:22:28 Worden (onboard): Really?

245:22:49 Worden (onboard): Well, I guess it doesn't make any difference on this food if we take it back home anyway.

245:22:58 Scott (onboard): Yes, that's probably true. They can decontaminate it back there.

245:23:02 Worden (onboard): Sure.

245:23:03 Scott (onboard): You can tell them we ran out, though. Do you think this salad's good, Al?

245:23:11 Worden (onboard): My what?

245:23:12 Scott (onboard): Sandwich spread ... It's a whole half a can.

245:23:16 Irwin (onboard): ...

245:23:17 Scott (onboard): Sure you can, Jim.

245:23:18 Worden (onboard): We have to finish after you.

245:23:21 Irwin (onboard): Okay, I'll eat it.

245:23:23 Worden (onboard): That's right.

245:23:24 Irwin (onboard): What?

245:23:30 Scott (onboard): If you wouldn't complain so much, we wouldn't leave you so much.

245:23:33 Irwin (onboard): You guys didn't leave me nothing.

245:23:36 Worden (onboard): Freak you!

245:23:38 Irwin (onboard): I'm thinking

245:23:39 Worden (onboard): (Laughter)

245:24:10 Scott (onboard): What kind of desserts we got there, Jim? A lemon pudding, huh?

245:24:16 Worden (onboard): Mmmm.

245:24:46 Irwin (onboard): ...

245:24:50 Worden (onboard): Yes, you're right, mouth, and I'm going to catch it ...

245:24:58 Irwin (onboard): I'm ready, if you can catch it.

245:24:59 Worden (onboard): (Cleared throat) That's the only way a power bowler makes it.

245:25:04 Irwin (onboard): ...

245:25:14 Scott (onboard): Huh? Yes, I suppose we ought to think about doing that. We can get to all that stuff now.

245:25:20 Irwin (onboard): Bright idea. ...

245:26:00 Scott (onboard): I would.

245:27:56 Scott (onboard): That's a pretty good sandwich.

245:27:59 Worden (onboard): Mm-bmm.

245:29:27 Scott (onboard): How much food we got left?

245:29:32 Worden (onboard): I don't know, at least a couple of days.

Public Affairs Officer - "This is Apollo Control at 245 hours, 30 minutes. Apollo 15's distance now 165,125 nautical miles [305,811 km]. Velocity: 3,137 feet per second [956 m/s]."

[The SIM bay power and communications links were re-established early and the X-ray Spectrometer started. Now Endeavour is maneuvered to aim the X-ray Spectrometer in the direction of the Scorpius X-1 x-ray source for 35 minutes. This was the first x-ray source to be discovered outside the solar system by a sounding rocket in 1962 at a time when many had believed there would be little to detect in x-rays above the atmosphere apart from the Sun. Later observations showed Scorpius X-1 to be a close binary star system in which material from a normal star accretes onto the surface of an extremely dense, collapsed star; probably a neutron star. The extreme temperatures reached in the process generate a prodigious x-ray flux.]

[The rest of the bay's instruments are also to be brought online. Associated with the X-ray instrument is the Alpha Particle Spectrometer. The Mass Spectrometer is deployed on the end of its boom and left to outgas for an hour or so. The boom for the Gamma-ray Spectrometer is to be deployed 4½ metres (15 feet). To do this, Al extends the boom fully, then, knowing how long a full retraction takes, retracts it for an appropriate fraction of that time.]

245:31:04 Scott (onboard): Six-foot waves in the recovery area, huh?

245:31:05 Worden (onboard): Yes.

245:31:06 Scott (onboard): That'll be sporty.

245:31:08 Worden (onboard): Yes, if we can dodge and land, that's great.

245:31:11 Irwin (onboard): Yes.

245:31:15 Worden (onboard): That's better than dead calm.

245:31:21 Scott (onboard): It is?

245:31:23 Irwin (onboard): Yes ....

245:31:25 Worden (onboard): It's probably because the power's ...

245:31:27 Irwin (onboard): Hmm.

245:31:28 Scott (onboard): That's why we had so much trouble on 9. ...

245:31:41 Worden (onboard): Why can't we just hop on over her pretty good in that fashion, too?

245:31:46 Scott (onboard): Yes.

245:31:49 Irwin (onboard): It's not that bad, boys.

245:33:23 Henize: 15, this is Houston.

245:33:29 Scott: Houston, 15. Go ahead.

245:33:31 Henize: Roger. Just sending up a reminder about the X-ray pointing attitude, which is due very soon now, and the activation of the SIM bay experiment.

245:33:43 Scott: Okay, Karl. Thank you.

[Long comm break.]
245:33:47 Worden (onboard): Okay, Houston. Boy, oh, boy, I used to think it was a good thing to get on a flight and then they could only talk at you one at a time. Whew, boy! Now, I think it's a good thing to get back so you - you don't have to listen to that goddam radio all the time.

245:35:00 Worden (onboard): The DAC, yes. But the Hasselblad's above your head.

245:35:05 Scott (onboard): No, mine's - I don't think so. No, that's Jim's.

245:35:13 Irwin (onboard): What else we got?

245:35:28 Worden (onboard): It's time for the UV stuff, huh? Let me get out of your way. You couldn't find any more pills, right?

245:35:36 Irwin (onboard): ...

245:35:41 Worden (onboard): No, I thought I put them in your TSB. I just saw them hanging there just before we started all that stuff, and I don't know.

245:36:02 Irwin (onboard): ...

245:38:22 Henize: Apollo 15, we'd like to have Omni Alpha.

245:38:31 Irwin: Roger; Omni Alpha. [Pause.]

[As Endeavour is maneuvered to the x-ray pointing attitude, the High Gain Antenna is liable to lose lock with Earth. By selecting one of the four omni-directional antennae mounted around the periphery of the Command Module, communication can be maintained, if at a lower quality than before.]
245:38:43 Worden: Houston, 15.

245:38:47 Henize: Go ahead, 15.

245:38:50 Worden: Okay, Karl. I'm ready to talk SIM bay; but first, a couple of questions.

245:38:53 Henize: Fire away.

[Comm break.]
245:40:00 Worden: Okay. What attitude do you want us to do the UV photo - photography at.

245:40:32 Henize: Roger, Al. The information on UV photos is to follow the procedures - Okay - you want the attitudes - the procedure's on page 3-352, and the attitude to be used is 210, 242, 322.

[Dave had requested that the UV photography session, planned to occur prior to the EVA, be postponed as all the required equipment was stowed in preparation for Al's excursion. Now Al has realised that in the six hours delay, the direction for pointing the spacecraft will have changed from that given in the procedures on page 3-352 of the Flight Plan.]
245:40:57 Worden: Say the attitude again, please.

245:41:00 Henize: 210, 242, 322. Also, note use of magazine P, and also the time - the time that we start the maneu - the time that we finish the maneuver is 247 plus 45. [Pause.]

[After each session of UV photography of the Earth, an additional image is taken using the same camera/lens combination, but using conventional colour film rather than UV-sensitive film. Henize is letting the crew know that this shot should be taken on magazine P instead of M as prescribed. He also reminds them of the time the new attitude numbers are relevant.]
245:41:35 Henize: And let me clarify that magazine. That is the magazine for the UV color for photographs. That is magazine P instead of magazine M.

245:42:02 Worden: Okay. Understand. Use the procedures on page 3-352, except change the attitude to 210, 242, and 322, and this whole thing is to be done at 247:45.

245:42:19 Henize: Roger. That's the time for completing the maneuver.

245:42:29 Worden: Well, what time would you like us to maneuver to that attitude then?

245:42:53 Henize: Roger. The time to start the maneuver is 24 - 247 plus 36.

245:43:03 Worden: I understand. 247 plus 36. Roger. Thank you, Karl. [Long pause.]

245:43:33 Henize: Okay, Al. Are you ready for the SIM bay questions?

245:43:43 Worden: Roger, Karl. Sure am.

245:43:47 Henize: Okay. First of all, the guys down here would like send up there warmest congratulations on such an ex - successful EVA. You sure made it look easy up there. And the questions. The questions we get are about the Mapping Camera, and they're directed at the general problem of is there - was there anything you could see which might indicate why it jammed? And there are three - three particular items that you might have looked at. First of all, it was the main camera cover at the bottom of the camera. Was it touching or scraping the camera in any way that you noticed?

245:44:29 Worden: The answer to that is negative. In fact. I checked it. I checked the Mapping Camera cover, Laser Altimeter cover quite carefully to make sure, because I do know that there have been some interference problems with that before, particularly with the Pan Camera, so I was looking at that in particular to see that it was maybe adjusted to close or - or interfering along the side of the Pan Camera, and it was not. There was about half an inch clearance between the upper edge of the cover and the body of the Mapping Camera, so that I - I don't see that that was responsible for the thing jamming.

245:45:07 Henize: Roger. I think you've very clearly put that suspicion to rest. There are also two covers to the solar camera in the upper left side of the Mapping Camera. And did you notice any - any distortion or any scraping in - in these covers? There's one possibility. The one that stuck out to the left - it - it might have jammed and the screwjack that controls it might have twisted it or distorted it. Was there anything you noticed like that?

245:45:37 Worden: Negative, Karl. I noticed nothing out of place with the Mapping Camera, nothing interfering. I checked all the way around it, down into the cavity, nothing interfering. I saw no evidence of anything interfering, and it looked clean underneath, so I don't think there was anything blocking it from underneath. I don't know. My distinct impression after surveying the Mapping Camera and looking around the cavity where the Mapping Camera fits was that there is a problem with its drive.

245:46:08 Henize: Roger. You didn't see anything inhibiting its motion, not even the electrical cables up on the top, huh?

245:46:14 Worden: Negative, and I guess I can ask a question along that line. Has anyone noticed any high current when we've gone to Retract on the Mapping Camera to indicate that it was hanging up?

245:46:28 Henize: We didn't see any, Al, although there had been a long controversy down here about the long amount of time required to extend and retract. It was, even though it was about the 4 minutes predicted several months ago, it was somewhat longer than what we'd observed at the Cape. People had been worrying about that for some time.

245:46:48 Worden: Yeah, I realize that. And I also, as I re - as I go back to what we saw at the Cape, there was some problems with that thing hanging up in drive itself at the Cape.

245:46:59 Henize: Roger. Okay, a couple of questions on the Mass Spectrometer. You gave us some good information there, but when you said the Mass Spectrometer cover wasn't completely closed, could you give us some idea at - as - to - to what degree it had closed, to what angle, and was there any poss - any cocking, any - any twisting in - in that cover.

245:47:28 Worden: Well, I couldn't tell whether there was any warpage in the cover or not, particularly because that kind of a cover is a little - looks like its warped anyway. It looked to me, I could - I pulled the cover out of the way enough to look at the Mass Spec. inside, and I could see the guide pin and along the sides of the carriage coming through the holes all the way up, so that they were plainly visible from the outside which - which meant to me that the - the Mass Spec. was either very close to being seated on the carriage or it was seated. I - I guess I don't really know how far those guide pins extend out beyond the - the carriage. The other thing was that the - that the cover - the Inconel cover was - it - was rotated about 30 degrees on it's - on it's hinge point from a full close position. And I thought at first, as I indicated when I was there, that there - there looked like there was some interference in one of the outer covers or one the outer edges, but after playing with that and pulling it a little bit when I was out there, it was quite obvious to me that that wasn't the problem either. And - and beyond that, I couldn't see down around beside the cover enough to tell whether there was something internal between the cover and the Mass Spec. that was - that was binding the cover.

245:48:52 Henize: Roger, Al. We copy that. And would you open the X-ray and Alpha Covers right now, please?

245:49:00 Worden: Okay, X-ray/Alpha Covers coming open.

245:49:05 Henize: Okay. I guess you've answered most of our questions on the Mass Spec., and you've approached one that we might get a little more out of, and that is those guide rails sticking through the guides. There is a tapered portion, and when it is completely seated, you actually see the - the - the cylindrical portion beyond the tapered portion. Did you actually see the cylindrical portion, or was it all tapered area that you looked at on the guide rail?

245:49:32 Worden: Okay, that's good scoop. All I saw was the tapered area.

245:49:37 Henize: Roger. You probably - If it was fully seated, you would have seen about a half inch of - of the cylinder there, and this is a good indication that it was not all the way seated even though it was close. [Pause.]

245:49:57 Henize: Here's a couple of other questions. Give me a second to look at them.

245:50:03 Scott (onboard): Why don't you get the ...?

245:50:04 Worden: Okay. [Long pause.]

245:50:40 Henize: Okay, Al. Mostly questions here about the contamination status and things in the SIM bay. First of all, how about the - the - the door eder - the door edges? Did they blow off smoothly and cleanly?

245:50:58 Worden: Yes, very cleanly. I saw no rough edges at all. [Long pause.]

245:51:22 Henize: Stand by a moment, Al.

245:51:26 Worden: Okay. [Long pause.]

245:51:27 Irwin (onboard): Don't forget to ...

245:51:29 Worden (onboard): Ion - Ion Source to Standby.

245:51:41 Henize: Al, we're anxious to bring up the High Gain Antenna. I've got a couple of angles here if they'll help.

[By using the HGA, Mission Control can acquire a greater amount of telemetry from the spacecraft's systems.]
245:51:48 Worden: Okay.

245:51:49 Henize: Minus 76 and 117.

245:52:03 Worden: Okay. Minus 76 and 117.

245:52:12 Henize: Okay. We copied your comment on the SIM bay door jettison, and further questions go as follows. The white coatings in the SIM bay were - Did you notice that any of them why - were obviously discolored or - or coated from contamination or overheating?

245:52:37 Worden: I saw no evidence of heating in the SIM bay. I saw no evidence of discoloration on the white surfaces. There were - [cough] - as - as best I could tell, no particulate matter that had come to rest on any of the surface in the SIM bay. It looked very, very clean. And - even across the top of the Mapping Camera where there was a - such a heating problem expected, I saw no indications of heating whatsoever, particularly on things like the cover over the Mapping Camera cassette, which was supposedly a very hot spot, and it was just as clean as a whistle. There wasn't - there wasn't any evidence of scorching or contamination anywhere that I could see.

245:53:23 Henize: Roger. And, on the insulation and foils, I guess there is a question here - Were any of them burned or discolored? You probably already told us that. Were any of them torn or were there any attachment failures?

245:53:46 Worden: No, I couldn't see any evidence of - of any burning or tearing or anything else back there, Karl.

245:53:59 Henize: Okay, we got one more general question there. And our Flight Dynamics Officer, who is vitally concerned about our reentry weight, would like to know whether we jettisoned more or less than a nominal 32 pounds; and, if so, by how much?

245:54:18 Worden: Okay. Stand by one. [Long pause.]

245:55:29 Worden: Say, Houston, we've talked it over, and I guess we'd say it was pretty close to a nominal - as far as weight. We have no idea of - of determining exactly what the weight was, but we're going to try and work our reentry stowage over this afternoon and tomorrow morning, and we hope to give you a - a plan by - somewhere around noon tomorrow, of where all the rocks are stowed and where everything is stowed and what we have on board. So you can start - so Mr. FIDO can work up his entry plan.

245:56:03 Henize: Roger. And, if somebody has time to copy it, I've got a small Flight Plan update available now.

245:56:14 Irwin: Okay, Karl. I'll take that.

[One of Jim Irwin's roles is to copy down Flight Plan changes as they are read up by the CapCom.]
245:56:17 Henize: Hi, Jim. How're you doing?

245:56:22 Irwin: Just fine.

245:56:23 Henize: Okay. 246 hours, 20 minutes; we have High Gain [Antenna] angles of pitch, 00; yaw, 240. At...

245:56:41 Irwin: ...00 and 240.

[These angles for the HGA are associated with a second x-ray pointing attitude at 246:20.]
245:56:44 Henize: Roger. And at 246 plus 46, we want to add "Change discriminator to low."

245:57:03 Irwin: Understand. Scratch "Discriminator, High," and make it "Discriminator, Low."

245:57:08 Henize: That's correct. And, on 247 plus 28, delete that DAP load.

245:57:20 Irwin: Okay. We already have that change.

245:57:23 Henize: Sorry about that. On 247 plus 30, we'd like to have the "Alpha/X-ray Covers, Closed; then Off", and delete the note on the Cover Open/Close.

[At the time given in this update, the spacecraft is to be placed into an attitude suitable for the PTC rotation. This is perpendicular to the Sun as required to spread its heat evenly across the outer skin as the spacecraft spins. The original plan had been to operate the X-ray/Alpha Particle Spectrometer during PTC, but to protect the instrument from damage, the covers were to be closed within certain angular limits once every 20 minutes. This onerous task would have been aided by setting a kitchen timer to warn of when to open and shut the covers.]
245:57:49 Irwin: Okay, understand. At 247:30, you'd like "Alpha/X-ray Doors, Closed," and just delete the note here.

245:58:00 Henize: Roger. And stand by one second. [Pause.]

245:58:10 Henize: 247 plus 30. Also, we would like to add "Mass Spectrometer Multiplier, High; Discriminator, Low."

245:58:34 Worden: Understand. At 247:30, you want to add "Mass Spec. Multiplier, High, and Discriminator, Low."

245:58:40 Henize: Rog. And, at 247 plus 32, we'd like to have "Mass Spec. Multiplier, High; Discriminator, High."

245:59:07 Irwin: Okay, 247:32, "Mass Spec. Multiplier, High, and Discriminator, High."

245:59:15 Henize: Roger. And I guess you need to save room, if there's any left there, because at 34 and at 36, we want to change these two switches again. At 34, we want "Mass Spec. Multiplier, Low; Discriminator, High."

245:59:40 Irwin: Understand. At 34 you want "Multiplier, Low; and Discriminator, High."

245:59:45 Henize: Affirmative and at 36, we want "Multiplier, Low; Discriminator, Low."

[Flight Plan page 3-360.]
246:00:01 Irwin: Okay. At 247:36, it's "Multiplier, Low; and Discriminator, Low."

246:00:05 Henize: Affirmative. Also at 247:36 is "Add the UV photos," and we've already sent up the changes required for that; the changes over and above what's on page 3-352. And there's one reminder there, and that is to verify that when you use filter 2, that you take one frame for 20 seconds and one frame for 2 seconds.

246:00:31 Irwin: Roger. We remember that.

246:00:33 Henize: Okay. The next step is 247 plus 45, "X-ray to Standby."

246:00:52 Irwin: Okay. At 247:45, "X-ray to Standby."

246:00:57 Henize: And, at 247 plus 50, we want to move the PTC initiation steps from 247:30 to 247:50.

246:01:24 Irwin: Okay. Understand. The initiation of PTC to be delayed from 247:30 to 247:50.

246:01:32 Henize: That's affirmative. At 248 hours and 0 minutes, we'd like the following: we'd like the Mass Spectrometer boom retraction sequence. Each retraction step will last 20 minutes, instead of 12. And terminate this test at 249 plus 30.

246:02:13 Irwin: Go back to 248, Karl, on that Mass Spectrometer boom retraction sequence.

246:02:18 Henize: Roger. I...

246:02:20 Irwin: I have that in there.

246:02:22 Henize: I - I guess all - all we're doing there is changing - The - the retraction step will be 20 minutes instead of 12 minutes. Down at the end of the writing there, it says "Each sample period will last 12 minutes." We'd like to have that at 20 minutes.

246:02:42 Irwin: Okay. I'll change the note there then. It occurs about 248:20; this 12 will be 20.

246:02:50 Henize: That's correct. At 249:05, we'd like to move the Mass Spec. boom deploy from 05 to 30 - from 249:05 to 249:30.

246:03:16 Irwin: Understand. Move the Mass Spec. boom deploy from 249:05 to 249:30.

246:03:30 Henize: Roger. And one final one at 251:48, which you may already have, is delete the DAP load there.

246:03:40 Irwin: I do; we have that one, Karl.

246:03:42 Henize: Okay. That completes the update. Thank you.

246:03:47 Irwin: Thank you. [Long pause.]

246:04:25 Henize: 15, Houston. We'd like to have Gamma-ray Gain Step up 4 clicks.

246:04:34 Irwin: Okay. That's Gamma-ray Gain Step up 4 clicks.

[Very long comm break.]

[In an attempt to keep them fit for a return to the strain of Earth's gravity acting on their limbs, the crew have a half-hour period of exercise.]

Public Affairs Officer - "This is Apollo Control at 246 hours, 15 minutes. Apollo 15 now 163,766 nautical miles [303,295 km] from Earth. Velocity: 3,171 feet per second [967 m/s]."

Public Affairs Officer - "This is Apollo Control at 246 hours, 20 minutes. Apollo 15 is maneuvering now to the x-ray pointing attitude."

[This is the second successive period of x-ray astronomy. This time the X-ray Spectrometer is to be pointed towards the constellation of Cygnus, primarily to observe the source, Cygnus X-1. Discovered just prior to the flight of Apollo 15 by the Uhuru satellite, this x-ray source is now believed to be a binary stay system in which one component star has collapsed to form a black hole which is consuming material from the other star. The intense heating of this matter as it spirals towards the event horizon of the black hole generates the huge x-ray flux.]

[Woods - "The astronomy that was done, the black hole, Cygnus X-1 and such like, were you much across what the scientists were hoping to do with the spectrometer? Was it just something afterwards you found out?"]

[Scott - "We were probably briefed before we went but we were briefed on a lot of things. Bitty, bitty, bitty experiments, if you will. I don't recall exactly. I'm sure somebody briefed us on the details but didn't really absorb them at the time. Jim and I are focussed on the surface. Al's focussed on trying to keep everything running. We had, I don't remember how many hours of microbiology scheduled when we first got assigned to the mission. Twelve to fourteen hours, something like that. Because you can't absorb it, you just can't take it all. There's too much to do."]

[O'Brien - "What kind of training in microbiology would they have you do and what would you do with that information once you got there."]

[Scott - "Bugs! They had a lot of stuff that, I don't remember how many hours. A lot of hours. They also wanted us to carry the waste management system, the new waste management system. We said no, because we don't want to take some new device on an already loaded spacecraft. And there was always this outside plethora of people who want things to be done on this flight. Things, things, things. At some point you have to cut it off and say no because in order to accomplish our major objective, we're saturated anyway. So at the beginning, we cut a lot of things out. And we added a lot of things too. We added a lot of geology. So there's a trade-off in what you really do."]

[O'Brien - "Was there anything that you felt short changed about in the end."]

[Scott - "No. Can't thing of anything. At the end of the day, that's why, when we got ready to go, we were ready. Probably wouldn't want to take another month of training. Be over-trained."]

[O'Brien - "Would have been more of a waste of time."]

[Scott - "Yeah, I think so. We probably peaked about when we should have peaked. Because we were sitting in the simulator, you know, last couple of days, we figured out how to simulate driving the rover on the model of the lunar surface. So Jim and I would sit in the simulator and pretend like we're driving the Rover. [Laughter.] It's because we'd done everything we could do. You could run another landing, another this, another that. But, you know, you're just saturated."]

[Woods - "Is that part of the thinking that says we've simmed all the horrendous things, we've done the training for the abort procedures. Let's do something that is nominal and then something that is fun to relax you a little bit the last couple of days before the flight."]

[Scott - "Sure. Yeah."]

[O'Brien - "Stories of people putting little toys on the models. You pitch over and there's Godzilla or something."]

[Scott - "Yeah. We did that. It was fun."]

[Once the exercise period is completed, the crew begin their meal break. During this, at 246:45, the Mass Spectrometer will have had enough time to outgas and will be switched on.]

Public Affairs Officer - "This is Apollo Control at 246 hours, 36 minutes. The high voltage has been turned on, on the subsatellite, everything is normal and the vehicle is considered fully operational."

246:37:35 Henize: 15, this is Houston. We trust you'll be pleased to hear the news that the high voltage has been turned on to the subsatellite, and that they find that all systems are operational.

246:37:50 Scott: Oh, that's very good. Glad to hear it.

[Very long comm break.]

[The subsatellite requires a high voltage power supply, derived from the solar cell supply to power its particle detector.]

Public Affairs Officer - "This is Apollo Control at 246 hours, 59 minutes. Apollo 15, is 162,429 nautical miles [300,819 km] from Earth. Velocity: 3,204 feet per second [977 m/s], and the clock counting down shows 48 hours, 11 minutes 'til landing. In the control center, Flight Director Glynn Lunney and his team preparing to relieve Flight Director Gerry Griffin, and his team of flight controllers. The CapCom on the next shift will be astronaut Bob Parker. ..."
[Flight Plan page 3-361.]
247:04:46 Henize: 15, Houston. We have a couple of more comments on the UV photo procedures, if somebody can copy.

247:04:56 Irwin: Go ahead, Karl.

247:04:59 Henize: Roger. We overlooked the fact that you are taking these photos in the midst of SIM bay operation, so a couple of little things change. Going back to page 3-352, you can first of all delete, below the damp rates notation, in - you can delete "Inhibit all jets, except" the jets that are there, and just keep the jet configuration you got right now.

247:05:43 Irwin: Okay. I copy that. Do you have any other comments?

247:05:46 Henize: Roger. Under "Remove the CM5 window," put in there "CMC, Free," and likewise, about four lines up from the bottom, just above "note", put in "CMC, Auto". And the final comment, "Enable all jets"; you can delete that. And that's all.

247:06:18 Irwin: Okay; understand. Just below "Remove CM5 window cover" put "CMC, Free," and then down at the - the bottom there, just above the note, put "CMC, Auto," and scratch "enable all jets."

247:06:35 Henize: Roger.

[Very long comm break.]
247:35:29 Worden: Houston, 15.

247:35:31 Parker: 15, go ahead; Houston.

247:35:39 Worden: Dr. Parker, I presume. Listen, Bob, we got to pull the Gamma-ray [boom] to 15 feet at 50, and wonder if you've got an updated retraction time for us.

247:35:49 Parker: That's affirm, Al. We have a retract time of 247 plus 50, for 72 seconds. Over.

247:36:00 Worden: Understand, 72 seconds.

[Both the Gamma-ray Spectrometer and the Mass Spectrometer are to be operated at various fractions of their booms' full 7-metre extension. The Gamma-ray boom was set to 4.5 metres when it was initialised at 245:30. In 15 minutes time it will be retracted to 2.4 metres and this will be achieved by operating its motor for 72 seconds, a value based on the boom's previous performance. This boom will be held in this position for 1 hour, 40 minutes.]

[In the meantime, Endeavour begins maneuvered to the attitude for the ultraviolet photography. This is carried out according to the procedures listed on page 3-352 of the Flight Plan.]

247:36:03 Parker: That's affirm. And, 15, if you got your Flight Plan out, we can update a couple more times in that same general vicinity for you.

247:36:19 Worden: Okay, the Flight Plan is out and the door is open.

247:36:23 Parker: Okay. At 248:02, the Mass Spec. boom retract time - that should be 33 seconds. And that time will apply to the first retraction. The second, third, fourth, and fifth retractions will be 32 seconds. Over.

[The progressive retraction of the Mass Spectrometer boom will be carried out in a slightly different manner. There will be five steps lasting 20 minutes each, between which the boom will be retracted for 33 or 32 seconds.]
247:36:51 Worden: Okay, Bob. Understand that the first retraction is 33 seconds and the succeeding retractions will be 32 seconds. Is that 4 or 5?

247:37:04 Parker: Stand by. [Long pause.]

247:37:33 Parker: Apollo 15, Houston. That will be 32 seconds for all succeeding ones, and we are going to do that up to 249:30. And so all succeeding ones you get will be at 32 seconds. And we will finish that test at 249:30, no matter where we are. And I believe I see that Karl has sent up comment that the sample period would be 20 minutes instead of 12. Is that right?

247:38:02 Worden: That's Roger; we have that.

247:38:04 Parker: Okay. And another change: at 249:36, the Gamma-ray deploy. That time will be 63 seconds. Over.

247:38:19 Worden: Copy, 63 seconds.

247:38:21 Parker: Okay. That's all we have for right now.

247:38:27 Worden: Okay, thank you, Bob.

[Long comm break.]
Public Affairs Officer - "This is Apollo Control. Flight Director Glynn Lunney is completing his mission status review with his Flight Controllers at the present time. ... At present time, Apollo 15 is 161,117 nautical miles [298,389 km] from the Earth and the spacecraft velocity is 3,237 feet per second [987 m/s]."

247:43:13 Parker: Apollo 15, Houston. Request Omni Delta, please.

247:43:20 Worden: Roger. Omni Delta.

[Very long comm break.]

[Having moved to the UV photo attitude, omni antenna D is best placed for communication with Earth.]

[Ultraviolet photographs are taken out of window 5 because it is constructed from quartz which transmits UV. A Hasselblad camera is fitted with a specialised 105-mm lens whose elements are likewise transparent to UV. Magazine N is used for this photography. The spacecraft is allowed to stabilise for 5 minutes with the FDAI set to its maximum sensitivity. Once stable, and in a change to the original procedure, the CMC mode switch is set to "Free" to inhibit further firing of the RCS thrusters, giving the crew a steady platform from which they can conduct the photography.]

[Eight frames are taken in all, two through each of four filters, though only seven appear in the Apollo 15 Index of 70-mm Photography, AS-15-99-13476 to AS15-99-13482. The proximity of the Sun to the camera's field of view is apparent in frame AS15-99-13478, taken through filter 2 with the Earth only dimly visible as a faint crescent in the central iris reflection. The linear marks to the lower right are cause by reflections from wipe marks on the window after someone has tried to clean the pane. A clearer image of Earth is in frame 13482, taken through filter 4.]

[Though an additional photo is to be taken through the same combination using colour magazine P, this magazine was exhausted in lunar orbit. Some colour photos of Earth were taken during the trans-Earth coast on magazine Q but they do not relate to this sequence of UV photos.]

[Afterwards, a protective cover is placed over window 5 and spacecraft attitude control is returned to the computer by placing the CMC switch to "Auto".]

[Flight Plan page 3-362.]

248:00:27 Parker: Apollo 15, Houston. Over.

248:00:35 Worden: Go ahead. [Pause.]

248:00:42 Worden: Houston, 15. Go ahead.

248:00:43 Parker: Roger, 15. If you guys will give us a hack when you start the first Mass Spec. retraction, we'll keep an eye on those 20-minute periods for you.

248:00:54 Worden: Okay; good deal. [Pause.]

248:00:57 Irwin (onboard): Just completed one.

248:00:59 Scott (onboard): Did you do one?

248:01:00 Worden (onboard): Yes. I'll talk to him.

248:01:01 Worden: Bob, we just completed one retraction for 33 seconds.

248:01:06 Parker: Okay, we're starting our time.

[Long comm break.]
248:01:11 Worden (onboard): ...

248:01:15 Irwin (onboard): And away we go.

248:01:17 Worden (onboard): ...

248:01:44 Irwin (onboard): Hey, you woke up just in time to eat again, Dave.

248:01:51 Scott (onboard): ... fresh.

248:01:54 Worden (onboard): To sleep in ... work ...

248:02:08 Worden (onboard): Okay, valve pressure is getting good and ... is ...

248:02:14 Worden (onboard): Surge tank pressure greater than 400?

248:02:15 Irwin (onboard): Yes, 487 ....

248:02:36 Worden (onboard): ...

248:02:48 Scott (onboard): Any surge?

248:02:50 Irwin (onboard): Yes, it's 600.

248:02:52 Worden (onboard): ...

248:02:54 Irwin (onboard): Yes.

248:03:00 Scott (onboard): ...

248:03:03 Worden (onboard): Yes. ...

248:03:13 Scott (onboard): ...

248:03:16 Worden (onboard): You got that solar stuff?

248:03:17 Scott (onboard): ...

248:03:26 Irwin (onboard): Sure a relaxed schedule here today.

248:03:28 Worden (onboard): We're going along all right until we get to ...

248:03:39 Irwin (onboard): You never do any more UV work, Al?

248:03:42 Worden (onboard): Yes, we get another one tomorrow.

248:04:11 Irwin (onboard): Hand me the log there, will you? Oh, we don't have the log out, do we?

248:04:16 Worden (onboard): ... find it.

248:04:21 Irwin (onboard): It might be in my TSB. My ... TSB.

248:04:33 Worden (onboard): ...

248:05:06 Irwin (onboard): Let's see. I have a G&C Checklist over here. But I don't have the - I don't have the other good information. I take it back; I have it. I have it.

248:06:20 Irwin (onboard): Did you take any UV photos in - in orbit?

248:06:27 Parker: Apollo 15, Houston. Over.

248:06:32 Worden: Go ahead. Go ahead, Houston.

248:06:37 Parker: Roger, 15. We'd like to get a pitch of minus 4.0 and yaw of 90 for the High Gain Antenna. And then, if you'd change your antenna switch to High Gain without hitting the Command Reset switch, we'll maintain comm that way, please.

[Comm break.]

[By the Flight Plan, the spacecraft would be in the PTC mode now. Instead, it is still in the UV photography attitude. The flight controllers are missing having full telemetry from its systems so have requested that the HGA be brought into operation. Al does maneuver Endeavour to the initial PTC attitude in less than 10 minutes anyway.]

248:06:59 Worden (onboard): Yes. Okay.

248:08:28 Parker: Apollo 15, Houston. Over.

248:08:38 Worden: Go ahead, Houston.

248:08:39 Parker: Negative. You did the right thing without us calling you. Thank you.

248:08:47 Worden: Whatever that was, okay.

[Long comm break.]
248:08:49 Irwin (onboard): Are we going to press on with the High Gain?

248:09:21 Scott (onboard): Yes, yes. If you just get your ... down here, ...

248:09:30 Worden (onboard): Ah, mark it.

248:09:32 Scott (onboard): ... We want to take four breathing samples and do our ... What do we have - we have about 50 left to make, don't we?

248:09:40 Irwin (onboard): We have 50 in this one.

248:09:41 Scott (onboard): ...

248:09:43 Worden (onboard): Okay.

248:09:44 Scott (onboard): ...

248:09:52 Irwin (onboard): Yes.

248:09:53 Scott (onboard): ...

Public Affairs Officer - "This is Apollo Control. The crew, at the present time, is setting up their Digital Auto Pilot and this will damp out the rates of the spacecraft, set it up in a stable position just prior to starting it rotating at the rate of about 3 revolutions per hour. And this is the condition that the spacecraft will be in during the sleep period to maintain the proper temperature and the proper thermal equilibrium. Prior to beginning the sleep period, which will be a 9-hour rest period, the crew will also run a Program 52 which is a platform alignment, aligning the stable platform used by their guidance and control system in the spacecraft as an attitude reference, and will also take a series of sightings on 3 different stars as part of a midcourse navigation exercise using Program 23. During this period of time also, they have [been] alternately extending and retracting the boom which holds the Mass Spectrometer. As the spectrometer moves alternately closer and farther from the Service Module bay, it allows the Principal Investigator to gather data on the cloud of contaminates that presume to follow along with the spacecraft, and to construct from this a stratification model of this contamination cloud. Once the model is constructed, then this data can be used to interpret the scientific results that are gathered with that instrument. At 248 hours, 12 minutes, Apollo 15 is 160,000 nautical miles [296,320 km] from the Earth and the spacecraft velocity is down, now, to 3,262 feet per second [994 m/s]; actually now, we're watching the velocity increase but very slowly and will continue to do so reaching its maximum shortly after Entry Interface where it'll be at about 36,000 feet per second [10,900 m/s] or a little more."

[The spacecraft has been maneuvered to the initial attitude for the PTC roll. This attitude is at right angles to the PTC REFSMMAT (the current alignment of the guidance platform) and essentially places the spacecraft's longitudinal axis broadside to the Sun, ensuring that, once it begins rotating, the heat received it evenly spread across its skin.]
248:13:23 Worden (onboard): ... change that one.

248:13:24 Scott (onboard): Bring it in ...

248:13:28 Irwin (onboard): You should bring that. I used the scissors to cut mine on the LM, but - Is there a file on the end of those scissors?

248:13:43 Worden (onboard): I don't think so. That one's ...

248:13:54 Scott (onboard): Not much of a file, huh?

248:14:00 Irwin (onboard): I got a razor blade (laughter).

248:14:02 Scott (onboard): ...

248:14:12 Worden (onboard): Yes.

248:14:13 Irwin (onboard): Yes.

248:14:14 Scott (onboard): ...

248:14:16 Worden (onboard): Okay.

248:14:17 Irwin (onboard): Okay.

248:14:17 Parker: 15, Houston, your rates look good to us for spinup.

248:14:23 Worden: Okay, Bobby.

[Long comm break.]

[During the PTC rotation, S-band communication is maintained by the HGA which is in its reacquisition mode. In this mode the antenna tracks the Earth on its articulated mount until the rotation of the spacecraft takes it to the edge of its range of movement. When this happens, the "Reacq" mode causes it to move to a setting that has been dialled in on the Main Display Console and which has been precalculated to bring it back onto Earth after the spacecraft has brought it around to the other side.]

248:15:38 Irwin (onboard): Maybe we better turn the heat up a little in here.

248:15:42 Scott (onboard): Getting cold?

248:15:45 Irwin (onboard): My feet are a little cold. I wonder where my - my little slippers went.

248:15:51 Scott (onboard): ...

248:15:53 Worden (onboard): Open up my - open up my sack. Here's my little slipper.

248:15:58 Scott (onboard): ...

248:15:59 Irwin (onboard): Get me into my slippers in here.

248:16:00 Worden (onboard): Are they yours?

248:16:01 Scott (onboard): Two-hundredths.

248:16:16 Irwin (onboard): I'll take them.

248:16:21 Worden (onboard): ...

248:16:25 Scott (onboard): ...

248:16:26 Irwin (onboard): Yes.

248:16:27 Scott (onboard): ...

248:16:31 Irwin (onboard): Yes, I think I did.

248:16:32 Scott (onboard): ...

248:16:42 Irwin (onboard): No. I think I - There is one.

248:16:43 Scott (onboard): Are you sure, Jim?

248:16:55 Irwin (onboard): The last time I saw it, we - it was in B-1. You know, wrapped in there with the - the jett bag. But it's not in there any longer.

248:17:04 Scott (onboard): ...

248:17:06 Irwin (onboard): No, it's not in there now. Just - just the - -

248:17:10 Scott (onboard): ...

248:17:11 Irwin (onboard): It's not in there now.

248:17:12 Scott (onboard): ...

248:17:14 Irwin (onboard): I don't know, Dave. I'll have to look. I don't know - I don't know who took that stuff out of B-1.

248:17:20 Worden (onboard): ...

248:17:21 Irwin (onboard): What'd you - Al, the one - the cam - we had the 500 - millimeter camera, Al?

248:17:27 Scott (onboard): ...

248:17:30 Irwin (onboard): Yes.

248:17:31 Scott (onboard): Remember, we pulled the cameras out ... and put them in the JETT bag.

248:17:35 Irwin (onboard): Yes.

248:17:36 Scott (onboard): I gave you yours, and you ...

248:17:39 Irwin (onboard): You gave me my camera at that time?

248:17:41 Scott (onboard): Yes, ...

248:17:45 Irwin (onboard): Tell me where it is and I'll lo6k.

248:17:46 Worden (onboard): Yes.

248:18:38 Irwin (onboard): Did you find ...?

248:18:39 Worden (onboard): Yes.

248:21:39 Parker: And, 15, time for the next cycle on the Mass Spec.: 32 seconds.

248:21:50 Worden: Okay. We were a little ahead of you that time.

248:21:53 Parker: Roger.

[Comm break.]

[This begins the second step in bringing the Mass Spectrometer incrementally towards the CSM.]

248:24:13 Parker: Apollo 15, Houston. Over.

248:24:18 Worden: Go ahead, Bob.

248:24:20 Parker: Roger. If you guys are - have a moment free, we'll pass up three comments to you preparatory to some stuff you want to do later on.

248:24:35 Worden: Yeah, go ahead.

248:24:37 Parker: Okay, first is a reminder that we're counting on using the OPS to pump up the cabin for sleep tonight - another way of bleeding off the OPS. Guess we'll remind you now so you don't stow it away down underneath something where it's inconvenient. And we'd like a read-out on the OPS after you finish pumping up the cabin tonight. Second comment is a reminder that we'd like a cue on the vacuum cleaner, if you intend to use it for this contamination control period coming up in a half hour or so, And third one is that as far as the medics are concerned, it's dealer's choice on who wears the biomed tonight. Over.

248:25:23 Worden: Okay, We copied, Bob.

[Long comm break.]

[Parker's last comment overrides the Flight Plan which, at 249:30, calls for Jim to wear his biomedical harness tonight. However, the crew will elect to stick with the Flight Plan.]

248:29:32 Parker: Apollo 15, Houston. Over.

248:29:38 Worden: Go ahead, Houston.

248:29:39 Parker: Roger. We'd like to confirm Auto, Auto, Off on the O2 heaters. It looks like we've gone beyond the point where they should have come on.

[By this, Parker means that oxygen tanks 1 and 2 should have their heater controls set to Auto with tank 3's heaters being switched off. The heaters in each tank are used to increase their internal pressure up to operating levels. Otherwise during use, the pressure falls as gas is extracted. The heaters can be set to switch automatically, controlled by a pressure-driven switch. Mission Control can monitor the pressure within the tank and are aware of the conditions that should trigger the heaters to come on.]
248:29:53 Worden: They're all Off right now, Bob.

248:29:56 Parker: Roger. That explains what we are seeing. Roger: we'd like Auto, Auto, Off, please.

248:30:07 Worden: Understand; Auto, Auto, Off.

248:30:09 Parker: Thank you. [Long pause.]

248:30:44 Worden: Houston, 15.

248:30:46 Parker: Go ahead, 15.

248:30:48 Worden: Okay, just wanted to clear up the O2 heaters with you. Are you aware that the last instruction that we had of the Flight Plan was at 243:30 that said "O2 Heaters, three, Off"?

[Al is mistaken here. The instruction, though, is badly formed and easy to misinterpret. This author (Woods) also made the same mistake (at first) when deciphering the line. The printed form is "O2 HEATERS 3 (1) - OFF" where the "(1)" indicates that only a single switch is being dealt with.]
248:30:59 Parker: Stand by. That wasn't on my shift.

248:31:05 Worden: You're not the regular crew chief, huh?

248:31:05 Parker: 15 - Apollo 15, Houston. That callout at 243:30 is the O2 heaters for tank 3, only.

248:31:36 Worden: Okay, Robert, I stand corrected.

248:31:55 Worden: That's one I owe you.

248:31:58 Parker: 15, you called?

248:32:04 Worden: Negative, negative.

[Long comm break.]
248:32:09 Irwin (onboard): I think this package of mags goes into A-8.

248:32:12 Scott (onboard): ...

248:32:17 Irwin (onboard): Ah, you think so, huh?

248:32:41 Worden (onboard): Should be pictures ... we used all that film. ... It picked up a little here ...

248:32:55 Scott (onboard): Who's going to ...?

248:32:58 Worden (onboard): Where's your bag? ...

248:33:06 Scott (onboard): It's down here right now. I got to get these straightened out.

248:33:18 Worden (onboard): ...

248:33:28 Worden (onboard): Yes.

248:33:29 Scott (onboard): ...

248:33:39 Worden (onboard): I'd like - I'd like to get a mag of that, too. Start eating it. ...

248:33:58 Scott (onboard): ...

248:34:06 Irwin (onboard): The mag, you mean?

248:34:08 Scott (onboard): ...

248:34:12 Worden (onboard): Well, no matter what you do, it's got to come back tightly, before you start it.

248:34:17 Scott (onboard): I knew you could, but you could - you could do it ... perfect here, or you could ... Now can you get it started?

248:34:30 Worden (onboard): Yes.

248:35:41 Irwin (onboard): Al, one pack of this film goes in A-8, the 70s in the LM.

248:35:48 Worden (onboard): Yes.

248:36:07 Worden (onboard): ... 40. Want three of them?

248:36:10 Irwin (onboard): Yes.

248:36:12 Worden (onboard): Did you get three?

248:36:13 Irwin (onboard): Yes.

248:36:14 Worden (onboard): Okay.

248:36:19 Irwin (onboard): We're going to get the other three in today. We'll have 13. We'll have to split the package up.

248:37:07 Worden (onboard): ... We can put some mags in here.

248:37:09 Irwin (onboard): Yes.

248:37:11 Scott (onboard): We only got this one mag.

248:37:16 Worden (onboard): ... that?

248:37:18 Scott (onboard): Right on. Why don't we just ...?

248:37:23 Worden (onboard): Probably, because nobody can ...

248:37:25 Irwin (onboard): Probably.

248:38:32 Irwin (onboard): ... in there? Al. That bag is much too big to fit in there.

248:38:43 Worden (onboard): ... but we can certainly get ...

248:38:47 Scott (onboard): We need one bigger than this, though.

248:38:49 Irwin (onboard): Well, this bag probably should not have come over from the LM. I used this bag, though, to wrap up these - these mags. You know, neither one have been used.

248:39:29 Worden (onboard): I think they might be ...

248:39:51 Scott (onboard): What are you going to get out of here?

248:40:01 Scott (onboard): Carry it for me. Can't help but be better.

248:40:12 Irwin (onboard): You got to work - work it out.

248:40:15 Worden (onboard): ....that one ...

248:40:18 Scott (onboard): ...

248:40:19 Worden (onboard): I wouldn't ...

248:40:22 Scott (onboard): Yes, I wouldn't ...

248:40:25 Worden (onboard): Yes. Tool - tool B on the - wait - wait a second.

248:40:48 Irwin (onboard): Tool B or tool E?

248:40:51 Worden (onboard): Tool B.

248:40:53 Irwin (onboard): From the LM?

248:40:55 Parker: Apollo 15, Houston. It's retract time.

248:41:04 Worden: Thank you, Bob.

[Very long comm break.]

[The Mass Spectrometer has been brought nearer the CSM for the third time.]

[Flight Plan page 3-363.]

248:41:41 Scott (onboard): What?

248:41:46 Irwin (onboard): Hey, I forgot to cut - I didn't cut the ion off.

248:41:50 Scott (onboard): Cut the ion ...?

248:41:52 Irwin (onboard): No. We should have cut the hammock straps. Should have got those, too, before we jettison them.

248:43:01 Scott (onboard): No, those are the LM pans. ...

248:43:22 Worden (onboard): Hey, Dave? Yes, you got them.

[There is a break in the onboard recording at this point.]
248:56:37 Irwin (onboard): We do UV photos twice. Two more - UV photos two more times.

248:56:45 Scott (onboard): ... your film.

248:57:13 Worden (onboard): It's kind of nice having some room down here, isn't it?

248:57:16 Scott (onboard): It sure is.

248:58:31 Irwin (onboard): You don't want to go through this contamination control with the vacuum cleaner, do you, Dave?

248:58:36 Scott (onboard): I don't think we're required to do it.

248:58:38 Irwin (onboard): Okay.

248:58:41 Worden (onboard): ...

248:58:43 Scott (onboard): No, we don't ...

248:58:45 Worden (onboard): We don't ...? ... mention down-range control. They're standing by to give some water on it anyway.

249:01:03 Parker: And, Apollo 15; Houston. It's time to retract again.

249:01:07 Irwin: Okay, thank you.

249:01:09 Parker: And, 15, be advised that this is the last retract we'll do. We will not do the fifth retract in order to ensure that we don't damage the filament by getting it in too close. We'll sit in this retracted position for 30 minutes, and then deploy the Mass Spec. boom as per the Flight Plan at 249:30. Over.

249:01:33 Irwin: Okay, understand.

[Very long comm break.]
249:19:15 Irwin (onboard): Oh, and then CDR doffing biomed harness. LMP donning. Alpha X-ray. Let's get a little SIM bay and then eat. Eat and then we do a canister change, You do a little P23 stuff. Then we'll get ready to go to bed.

249:19:46 Worden (onboard): Three hours to bedtime.

249:19:50 Scott (onboard): ... sleep ....

249:20:05 Worden (onboard): ... 3 to 4 hours ...

249:20:22 Scott (onboard): ... here?

249:20:25 Worden (onboard): ...

249:20:26 Irwin (onboard): Otherwise, it would have been pretty boring.

249:20:28 Scott (onboard): ...

249:21:32 Worden (onboard): ...

249:21:39 Scott (onboard): ...

249:21:40 Worden (onboard): ...

249:21:50 Irwin (onboard): (Laughter)

249:21:51 Worden (onboard): ...

249:21:55 Irwin (onboard): Yes.

249:21:56 Worden (onboard): ...

249:22:06 Scott (onboard): ...

249:22:09 Irwin (onboard): You work mighty hard, I'll tell you.

249:22:11 Scott (onboard): What ...?

249:22:12 Irwin (onboard): You work mighty hard.

249:22:20 Scott (onboard): ...

249:22:23 Irwin (onboard): No, a little ...

249:22:35 Irwin (onboard): I wish I would have tried running alongside the Rover at a - the same pace, you know, to see how...

249:22:42 Scott (onboard): You'd have never stayed with it, Jim. You know ...

249:22:47 Irwin (onboard): Yes, true.

249:22:48 Scott (onboard): ...

249:22:56 Irwin (onboard): I would have liked to have, you know, to run alongside of it. It'd been neat to do a few things like that, you know.

249:23:01 Scott (onboard): What?

249:23:02 Irwin (onboard): It'd been neat to try a few things like that.

249:23:04 Scott (onboard): Yes. I know. Yes. ...

249:23:43 Irwin (onboard): You can take off your biomed harness, Dave.

249:23:44 Worden (onboard): Whoo!

249:24:05 Irwin (onboard): He'll lose sleep for 9 hours tohight.

249:24:08 Scott (onboard): Good! ...

249:24:35 Scott (onboard): Can you see the Moon?

249:24:36 Irwin (onboard): Oh, yes.

249:25:45 Worden (onboard): Can you get that? Thank you.

249:25:58 Irwin (onboard): On a lunar eclipse - Let's see, we take a total there of...

249:26:06 Scott (onboard): ...

249:26:07 Irwin (onboard): No, we take some with the EL.

249:26:10 Scott (onboard): Yes.

249:26:11 Irwin (onboard): Yes. We take eight with the EL.

249:26:13 Scott (onboard): What kind?

249:26:14 Irwin (onboard): Color.

249:26:17 Worden (onboard): ...

249:26:27 Scott (onboard): Yes, eight with color.

249:26:40 Irwin (onboard): Here's some more Lunar Orbiter.

249:26:44 Scott (onboard): Is that the same?

249:26:47 Irwin (onboard): No, you have it on two different pages.

249:26:51 Scott (onboard): Oh, yes.

249:26:54 Irwin (onboard): Hey, what was this one for?

Public Affairs Officer - "This is Apollo Control at 249 hours, 27 minutes. Apollo 15 is now 157,700 nautical miles from the Earth, traveling at a speed of 3,322 feet per second. The crew, at this time, should be about to get something to eat. Following the eat period they'll be aligning their platform, the guidance system stable platform used in attitude reference. And [they] will also be taking some star sightings using program 23 for midcourse navigation. During the rest period, which is scheduled to begin at 252 hours, 32 minutes, or about 3 hours from now, the Gamma-ray, Alpha Particle and Mass Spectrometers will be operating, gathering background data to be compared with the information collected in orbit around the Moon."

249:27:08 Scott (onboard): Don't you have any more?

249:27:09 Worden (onboard): ... think we need any ...

249:27:12 Scott (onboard): Yes ....

249:27:15 Irwin (onboard): It's in the lockers.

249:27:20 Scott (onboard): ... more?

249:27:22 Worden (onboard): ... time to figure it out - figured out ...

249:27:26 Scott (onboard): Going to give them ...?

249:27:31 Worden (onboard): ...

249:27:34 Scott (onboard): ...

249:27:38 Worden (onboard): Yes, you got to reckon with him yet.

249:27:40 Scott (onboard): Huh?

249:27:41 Worden (onboard): You're going to have to reckon with him yet on those ...

249:27:42 Scott (onboard): Yes. ... make sure to recommend that he ...

249:27:49 Worden (onboard): Yes.

249:27:52 Scott (onboard): ...

249:28:00 Worden (onboard): Yes.

249:28:24 Parker: Apollo 15, Houston. About 2 minutes to Mass Spec. boom deploy. And we'd like a Delta-T on the length of time it takes to deploy it, please.

249:28:37 Worden: Roger, Bob.

[Long comm break.]
249:29:51 Scott (onboard): (Laughter) They can't tell that, I don't think.

[With this being essentially an engineering test flight for the SIM bay, Al carefully timed the deployment and retraction of the booms and the Mapping Camera throughout his solo mission. Mission Control are asking him to continue this practice so that they can check that the deployment time is consistent with how far they believe the Mass Spectrometer boom was retracted. This is especially important in light of the difficulty Al had at times in retracting this boom, a problem which turned out to be caused by excessive cold.]

[Note that the Gamma-ray boom is retracted also to operate for the next 2¾ hours close to the spacecraft.]

249:33:43 Irwin: Bob, the flight time [time for retraction] on the Mass Spec. was 3 and 25.

249:33:50 Parker: Roger. Copied 3 plus 25, Jim.

249:33:53 Irwin: Roger.

[Very long comm break.]

[Dave, Al and Jim begin their final meal period of the day. After that they have two hours of activities before settling down to rest. The major activities will include a P52 platform realignment, some P23 cislunar navigation exercises and a reestablishment of the PTC rotation.]

249:43:03 Scott (onboard): There must be a mag around somewhere. There must be two of them.

249:43:07 Worden (onboard): In the bag.

249:43:09 Scott (onboard): Okay.

249:43:11 Worden (onboard): Now, all we're missing is S, per his ...

249:45:32 Worden (onboard): Is that mag hooked up?

249:45:35 Scott (onboard): I don't know.

249:45:58 Worden (onboard): I've got - I've got two whole reels of color stereo.

249:48:50 Worden (onboard): Yes, that goes back up for ...

249:48:55 Scott (onboard): Why?

249:48:56 Worden (onboard): Why?

249:48:57 Scott (onboard): Why?

249:49:08 Scott (onboard): Let's see. Next is the ...

249:52:53 Scott (onboard): Huh?

249:55:17 Scott (onboard): Huh?

249:55:26 Worden (onboard): One more time. Ready?

249:55:27 Scott (onboard): Yes.

249:56:47 Parker: Apollo 15, Houston. While you're eating your supper there, I thought you might be interested in knowing how the vectors are going. Your vector and the ground's vector are extremely close, and - at least at the moment - we'll see what happens when we take the next P23. Right now we're looking at no midcourse 6 and about 1.8 foot per second for midcourse 7.

249:57:22 Worden: Houston, 15. That sounds pretty good, and it looks like we'll see what happens on the P23. One - You say 1.7 on midcourse 7 is what it looks like right now.

249:57:32 Parker: Roger; 1.8. The vectors, I guess right now, about 4,000 feet apart and about a couple of feet per second in velocity and no more.

[Endeavour's computer has two spaces set aside in its memory to store two state vectors. On the way out from Earth, a copy of the LM's state vector was kept in one of these. Now on the return leg with the LM left behind on the Moon, this slot is used by Al to keep the state vector that he calculates using his own sightings and P23 in the computer. These state vectors are collections of seven values which define the position and velocity of the spacecraft as expressed in three axes. The seventh value is the time at which the other values are current. A comparison of Al's vector with that calculated by the computers in Mission Control shows that the difference between them is indeed slight. Only 1.2 km separates them across the 400,000 km gulf between the Earth and Moon, and less than 1 metre per second in the velocity of a craft moving at over 1,000 metres per second.]
249:57:44 Worden: Sounds great.
[Very long comm break.]

[Flight Plan page 3-364.]

Public Affairs Officer - "This is Apollo Control. We've still got about 5 or 10 minutes left in the crew eat period. They'll be finishing up their evening meal before completing the last activities, prior to their sleep period. That'll be a platform alignment, and some midcourse navigation. A little while ago, spacecraft communicator, Bob Parker, told the crew that it did not appear, at this time, that we would have to do a midcourse correction at the midcourse correction 6 opportunity, which is in about 22 hours, at 272 hours, 58 minutes. Possibly a small midcourse correction will be required just prior to entry at 291 hours, 58 minutes. However this would, at the present time, appear to be only about 1.8 feet per second [0.55 m/s] velocity change, which would be well within the capacity of the Reaction Control System thrusters. It probably would be a 2 jet burn, using just 2 of the attitude control thrusters. One of the clocks in Mission Control at this time is counting toward splashdown; 44 hours, 35 minutes from now; and the Flight Dynamics Officer reports that the spacecraft appears, at this time, to be comfortably within the entry corridor, with an entry angle at - entry interface of about, negative 6.69 or 6.7 degrees. The normal, or preferred is about 6.5, but 6.7 is considered within the entry corridor. ... Apollo 15, at the present time is 155,500 nautical miles [287,986 km] from the Earth, and the spacecraft velocity is 3,382 feet per second [1,031 m/s]."

250:10:38 Worden (onboard): You got it?

250:10:39 Irwin (onboard): Over here.

250:10:40 Scott (onboard): Oh, yes.

250:12:22 Worden (onboard): God damn.

250:12:23 Scott (onboard): Huh?

250:13:11 Scott (onboard): Al, what all is there?

250:13:29 Worden (onboard): We have turkey.

250:13:34 Scott (onboard): Turkey?

250:13:35 Worden (onboard): Yes.

250:14:22 Scott (onboard): Do we have something extra for lunch?

250:14:37 Worden (onboard): Ham.

250:15:26 Scott (onboard): As you're loading it.

250:15:29 Worden (onboard): Oh, I - you know, I think we can do it with ...

250:16:03 Worden (onboard): Ah, yes.

250:16:16 Scott (onboard): Hey, I'd - I'd like to ... Yes. ...

[There is a break in the onboard recording at this point.]
250:35:08 Worden (onboard): I'm just fine. Just fine.

250:35:24 Worden (onboard): I'm so damn happy; nobody could give me any better service.

250:37:40 Scott (onboard): What seems to be ...?

250:38:20 Worden (onboard): Hey, what do you ...?

250:38:25 Scott (onboard): Yes. Yes, ...

250:38:44 Scott (onboard): ...

250:38:45 Worden (onboard): ...

250:38:48 Scott (onboard): ...

250:39:30 Worden (onboard): Yes, I guess the worst thing in the world would be to try to do something like that and not be able to do it.

250:39:35 Irwin (onboard): Oh, boy, ...

250:39:50 Worden (onboard): Tired?

250:39:52 Scott (onboard): Yes.

250:40:01 Worden (onboard): Well, I'll tell you, I'm sure glad we got rid of that clothesline operation ...

250:40:06 Irwin (onboard): ...

250:40:16 Worden (onboard): In fact, it's really a ball, when you get all suited up, get cooled off, and get the hatch open.

250:40:24 Irwin (onboard): Sounds good. Sounds real good.

250:40:29 Scott (onboard): Oh, it's great.

250:40:32 Worden (onboard): The Sun would have been some better - It would have been better if it could have been a little bit higher. Because when I went down around the side of the mapping camera, it was pretty dark.

250:40:47 Scott (onboard): Yes.

250:41:06 Scott (onboard): Yes.

250:41:19 Worden (onboard): Boy, I hope the - I hope the TV came out all right.

250:41:23 Scott (onboard): Yes ....

250:41:25 Worden (onboard): Did you? Okay. ...

250:43:17 Scott (onboard): Got them. Got them.

250:43:18 Worden (onboard): Okay.

250:43:19 Scott (onboard): Somehow they got way down in there...

250:43:20 Worden (onboard): Well, we didn't lose anything of value out the hatch. ...

250:43:23 Scott (onboard): Everything's okay.

250:43:25 Worden (onboard): We lost a spring clip. We lost a paper clip...

250:45:04 Parker: Apollo 15, Houston. We can terminate battery Bravo charge now.

[Battery B has been charging for the last 6 hours.]
250:45:16 Irwin: Houston, 15. Roger; will do. [Pause.]

250:45:32 Parker: And 15, Houston. A reminder that when we exit PTC in about 15 minutes, we'd like to do it using the SIM bay RCS configuration.

[Al has to stop the PTC rotation to carry out his cislunar navigation sightings. When he does so, he will avoid using the thrusters that impinge on the SIM bay.]
250:45:46 Irwin: Roger, Houston; understand.
[Very long comm break.]

[Al now realigns the spacecraft's guidance platform to the PTC REFSMMAT. As usual, Mission Control can copy the gyro torquing angles from their telemetry mirror of the DSKY's displays.]

250:57:43 Worden (onboard): Want me to write?

250:57:46 Scott (onboard): Where do you want this? In your ...?

250:59:24 Scott (onboard): Okay. Plus four balls 8, minus three balls 67, plus three balls 54.

250:59:34 Worden (onboard): Wait a minute; maybe that's 34.

250:59:41 Scott (onboard): Oh, yes.

250:59:42 Worden (onboard): Yes.

251:00:23 Scott (onboard): Oh, you screwed up.

251:01:22 Parker: And, 15, this is Houston. We have your torquing angles. That's some platform, isn't it?

251:01:31 Scott: Yes, sir, Bob. You bet you; it sure is beautiful.

[Flight Plan page 3-365.]

[Very long comm break.]

[Al continues his program of sightings designed to navigate him and crewmates home safely in case of a loss of communication with Earth. Once he has stopped the PTC, calibrated the optics and maneuvered to the appropriate attitude, he begins with marks on Pollux, one of the twins of Gemini, followed by Earth's horizon nearest the star. The process is repeated twice using Aldebaran, in Taurus, and Capella, in Aurigae; each time measuring angles to Earth's horizon furthest from the star.]

251:01:35 Scott (onboard): You say that sure has been planned for me?

251:01:41 Worden (onboard): Yes, ...

251:02:08 Scott (onboard): ...

251:02:09 Worden (onboard): The platform gets us home without a midcourse, by golly.

251:02:16 Scott (onboard): No range error, but pressure's a little low.

251:02:18 Worden (onboard): Hey, Jim. While you're down there, we need a canister change. Twenty-one into B. Stow 19 in A-4.

251:03:51 Scott (onboard): Twenty-one. Yes. Twenty should be in A. Get it out of A-4.

251:04:21 Scott (onboard): No!

251:04:22 Worden (onboard): ... catch it.

251:05:03 Scott (onboard): That a boy.

251:05:04 Worden (onboard): Lock her, Dave. You can ...

251:05:07 Scott (onboard): ...

251:05:09 Irwin (onboard): Yes, it is. I think we can ... I hate to use those pulleys.

251:05:16 Scott (onboard): ...

251:05:20 Worden (onboard): Yes. If you use your own tool.

251:05:30 Irwin (onboard): ...

251:05:34 Scott (onboard): Who stole my ...? (Cough) Boy, ..., didn't I?

251:05:44 Worden (onboard): ...

251:07:32 Worden (onboard): What are you doing?

251:07:42 Worden (onboard): Thank you, Davey.

251:17:37 Parker: Apollo 15, Houston. Over.

251:17:45 Worden: Houston, 15. Go.

251:17:46 Parker: Roger. Mister Lightning Fingers, we'd appreciate it if you'd keep your Noun 49 on for about 5 seconds on this P23, so we get a nice chance to look at it here on the ground. [Laughter.]

251:18:01 Worden: I will do my best, sir.

[Very long comm break.]
Public Affairs Officer - "This is Apollo Control. Al Worden is presently using program 23 to update the spacecraft guidance systems knowledge of the trajectory. Taking sightings on stars and marking. This information is integrated into the computer memory and is used to update the state vector or the trajectory information contained. This is the last task that the crew has to perform prior to beginning their rest period, and just before deploying the Gamma-ray boom. During the sleep period they will be in Passive Thermal Control mode with the Gamma-ray, Alpha Particle and Mass Spectrometers collecting data."

251:42:53 Parker: Apollo 15, Houston. Over.

251:42:59 Worden: Go ahead, Houston; 15.

251:43:01 Parker: Super marks, Al. You can do my P23s any day.

251:43:09 Worden: They looking okay down there, Bob?

251:43:10 Parker: Roger. We caught all of them. Hey, when you go back into PTC now, we'd like to change Noun 79, the rate one anyway, to a minus .42. Over.

251:43:25 Worden: Going to try a little higher one, now? Okay, minus .42.

[When Al first set up a PTC roll during the translunar coast, he had a couple of attempts at getting what was a new procedure to work smoothly. During the troubleshooting then, Mission Control asked him to enter a higher rate of rotation into the computer, up from 0.35°/sec to 0.38°/sec. Now, for reasons unknown at the time of writing, this is being raised once more to 0.42°/sec making the spacecraft rotate once every 14¼ minutes.]
251:43:29 Parker: Roger. [Long pause.]

251:43:46 Parker: And, 15; Houston. If you've got a minute, we've got a couple more comments for you.

251:43:52 Worden: Okay. Anything I need to write down?

251:43:55 Parker: Negative. Number...

251:43:59 Worden: Okay. Go ahead.

251:44:00 Parker: ...number one, we'd like to know the film status of magazine Victor. And number two, if you're planning on being the loop tonight, Al, for the biomed, your harness needs some attention. The heart rate that we're getting down is getting a little noisy. Over.

251:44:23 Worden: Well, in the first place, my heart rate is always noisy; and, in the second place, I guess Jim's going to be on tonight.

251:44:29 Parker: Understand.

[Comm break.]
251:45:41 Worden: Houston, 15.

251:45:45 Parker: 15, Houston. Go.

251:45:48 Worden: Okay, Bob. Mag Victor is 12 frames expended.

251:45:54 Parker: Copy, 12 frames expended. Thank you.

[Very long comm break.]
251:57:26 Parker: 15, Houston. We suggest that you go ahead with your Gamma-ray deployment while you're doing your rate damping.
[Having spent the last 2¾ hours operating while retracted, the Gamma-ray Spectrometer will be deployed at the full extent of its boom. In terms of Parker's comment, it may also be that having the boom extended makes it easier to stabilise the spacecraft's motions prior to PTC.]
251:57:38 Scott: Roger, Houston.
[Comm break.]

[Flight Plan page 3-366.]

251:59:19 Parker: And, 15; Houston. If you feel like it, we can take your E-mod now.

251:59:26 Scott: Okay. Coming you're way. [Long pause.]

252:01:05 Parker: And, 15, we have your E-memory dump.

252:01:11 Scott: Okay, good.

[Long comm break.]
252:04:37 Parker: 15, Houston. We're Go for spinup - for PTC.

252:04:43 Scott: Okay, good.

[Very long comm break.]
252:19:16 Irwin (onboard): What are you doing there, man?

252:19:18 Scott (onboard): ...

252:19:21 Irwin (onboard): Did you find it?

252:19:33 Worden (onboard): That's better.

252:19:36 Scott (onboard): ...

252:19:37 Irwin (onboard): Yes, I wouldn't know the switches on it.

252:19:41 Scott: Houston, Apollo 15.

252:19:45 Parker: Apollo 15, go.

252:19:50 Scott: Hi, Bob; got a presleep checklist for you.

252:19:55 Parker: Shoot; we're ready. Dave, hold on. We got a...

252:19:59 Scott: Okay. [Long pause.]

252:20:16 Parker: Okay, 15, we're back with you. We just had a site changeover.

252:20:23 Scott: Okay. Crew status is all good, no medications. And I've got the onboard read-outs if you've got a pencil.

252:20:31 Parker: I've got a pencil.

252:20:34 Scott: All righty. Starting with Bat C, 37.0, 37.0, 37.0; RCS A is 56, B is 50, 48, and 52. And I guess everything else has been done, and I guess you got your E-memory dump. We pressurized the cabin with the OPS, and, when we got to about 5.7 or 5.8, the OPS was down to 800. And I reckon that's the size of it.

252:21:10 Parker: Roger, Dave. That sounds like the size of it to us. We copy all that, and there will be no vector update. Ground says your vector is just as good as theirs right now.

252:21:22 Scott: How about that? Oh, that's pretty good. We got a good navigator.

252:21:27 Parker: And, 15, let's hold a couple of minutes while we check some data on SIM bay and while we go around the MOCR one more time. And we'll be back with you in final status, I hope.

252:21:42 Scott: [Laughter.] Okay, we got - we got time. We're not quite ready to go to bed yet.

[Long comm break.]
252:22:04 Scott (onboard): (Laughter) Bob says, if he - says, okay, let me go around to the MOCR and check it and come back with your final status, I hope.

252:22:24 Scott (onboard): But, you know, they got to old Joe, I can tell. Joe's changed. He's a changed man. They had him, boy.

252:22:32 Irwin (onboard): They did?

252:22:33 Scott (onboard): They were all over his ass during that EVA. He was just really humping. That poor fellow - I bet he's exhausted.

252:22:49 Scott (onboard): He probably had so damn many inputs, he didn't know which way to go.

252:23:04 Worden (onboard): ...

252:23:08 Scott (onboard): Huh?

252:23:09 Worden (onboard): ... apart.

252:23:14 Scott (onboard): Oh, he's pretty close to them. That - that group's all tied together pretty well. Yes. It was in pretty good shape. We got all those guys out on the field trips and sat down and talked to all of them, and that - that group's pretty well squared away.

252:23:28 Worden (onboard): ...

252:23:32 Scott (onboard): No, they're in the back room. And the guy who really comes up to him is Jerry Griffith.

252:23:40 Worden (onboard): Oh, yes?

252:23:41 Scott (onboard): He's really the experiments officer. But...

252:23:45 Irwin (onboard): Who's Jerry Griffith?

252:23:46 Worden (onboard): Yes (laughter).

252:23:47 Irwin (onboard): ...

252:23:48 Worden (onboard): Yes.

252:23:50 Scott (onboard): And - But it really goes from Gordon Swann through Griffith to the Flight Director to Joe. And it's - it's a straight loop because Griffith and Griffin both understand the problem, so it - it isn't any big deal. Except that all the other people who aren't in the loop and don't understand were there - all the guys up in the back row with their input - with them.

252:24:12 Irwin (onboard): ...

252:24:15 Scott (onboard): Jerry Griffin said he - one of his main problems was going to be holding the people off behind him - you know, to let Joe do his Job, and I'm sure it was ... - especially when they can see it all on the TV. And they're clanked...

252:24:29 Irwin (onboard): They're all there?

252:24:30 Scott (onboard): Yes. They're all clanked up anyway. Then we go up on top of some big frigging mountain or stand right next to some big frigging valley, and, you know, they can't do anything about it; they're all bunched up like a nickel cigar.

252:24:40 Irwin (onboard): ... They ... and. ...

252:24:44 Scott (onboard): Yes.

252:24:45 Irwin (onboard): And ...

252:24:46 Scott (onboard): Yes.

252:25:15 Parker: Apollo 15, Houston, the only thing we show lacking at the moment is Gamma-ray Gain Step, Shield, On. Other than that, you're Go for sleep.

252:25:27 Scott: Okay, understand. Gain Step, Shield, On.

[Very long comm break.]
Public Affairs Officer - "This is Apollo Control at 252 hours, 35 minutes. The crew is scheduled to be in their sleep period at this time. However, Dave Scott mentioned a few minutes ago that they still had a few things to complete before they tried to get some sleep. We'll keep the air to ground lines up live until it appears from the biomedical data that the crew is in fact beginning to drop off to sleep at which time we'll take the lines down, keep the recorders running to record for playback any conversations that should develop unexpectedly. Apollo 15, at the present time, is 151,632 nautical miles [280,822 km] from the Earth and the spacecraft velocity up now to 3,485 feet per second [1,062 m/s]. During the sleep period, as is normally the case, the spacecraft will be rotating at a slow rate to maintain proper temperatures. Tonight, that rate just a tad higher than it's been, rotating at the rate of about 4 revolutions per hour instead of the normal 3 to 3¾. And we understand this is being done because the booms supporting the Mass Spectrometer and Gamma-ray Spectrometer are deployed. The Lunar Module Pilot, Jim Irwin, will be wearing the biomedical harness during the sleep period tonight; we'll have heart and respiration rates on him which will be our indicator that he is beginning to sleep and by inference that the crew is dropping off to sleep."

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