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Apollo 15

Day 10, part 7: Settling down for the Journey Home

Corrected Transcript and Commentary Copyright © 2000-2023 by W. David Woods and Frank O'Brien. All rights reserved.
Last updated 2023-10-27
Index to events
Flight Plan updates 225:26:21 GET
Presleep pnboard readouts 228:10:40 GET
Approaching the tenth day in the Apollo 15 mission and the Apollo 15 Command and Service Module, Endeavour, has just fired its SPS (Service Propulsion System) engine to take it out of lunar orbit on a trajectory for Earth. The three crewmen, David Scott, Al Worden and Jim Irwin, can now begin to settle down for the three-day coast from planet to planet. Tomorrow, Al will leave the Command Module on an EVA (Extra Vehicular Activity) to the SIM (Scientific Instrument Module). This evening there is only housekeeping to do before they begin their rest period.
[Download MP3 audio file. Clip courtesy National Archives and Records Administration.]
224:44:47 Parker: And, Apollo 15; Houston. We'd like that Verb 49 maneuver, so we can pick up [the] High Gain [Antenna], please.
224:44:58 Worden: Roger. We just did it, Bob.
As their spacecraft pulled away from the Moon, Al manoeuvred it to an attitude that would afford the crew and the Mapping Camera a good view of the receding lunar disc. Since, during the early stages of their departure, the Moon would be moving through their field of view rather quickly, another attitude had been given to the crew that would keep the camera's aim true. Appropriate angles for pointing the HGA (High Gain Antenna) were not given until this latter, longer-duration attitude became current. The manoeuvre is made by entering the three given attitude angles into Verb 49. Once the spacecraft has rotated to that attitude, the HGA angles also become current and a high quality link with Earth can be achieved once they are set.
224:45:01 Parker: Thank you. [Long pause.]
224:45:16 Scott: Hey, Houston. Take a look at the DSKY. I think those are the numbers you gave us.
224:45:26 Parker: Roger, 15. Those are the numbers. Looks good, thank you.
Very long comm break.
By this time, Endeavour is about 2,300 nautical miles (4,300 km) from the Moon. The occasional photography that the crew have been carrying out since TEI continues with four images taken on colour magazine Q using a 250mm lens.
AS15-96-13094 - View towards lunar north pole including Mare Smythii and Mare Marginis - Image by NASA/Johnson Space Center.
AS15-96-13095 - View towards lunar north pole including Mare Smythii and Mare Marginis - Image by NASA/Johnson Space Center.
AS15-96-13096 - View towards lunar north pole including Mare Smythii, Mare Marginis and Mare Crisium - Image by NASA/Johnson Space Center.
AS15-96-13097 - View towards lunar north pole including Mare Smythii and Mare Marginis - Image by NASA/Johnson Space Center.
The approximate distance at which these photos were taken is being determined for this journal by using the curvature of the Moon and other data (lens, film gate, etc.). By this technique, it appears that the next two photos to be taken are on magazine TT at distance of about 2,380 nautical miles (4,400 km). TT contains colour film and the assumed lens is the 60mm wide-angle lens.
AS15-88-12013 - Lunar disc, about 1 hour after TEI - Image by NASA/Johnson Space Center.
AS15-88-12014 - Lunar disc, about 1 hour after TEI - Image by NASA/Johnson Space Center.
The next set of photos to be taken use the 500mm lens with a black and white film magazine, RR, to spot detail across the visible hemisphere.
It should be noted that there is a disagreement between the numbering of these scans between various online libraries. The catalogue at the Lunar and Planetary Institute matches the Apollo 15 Index of 70mm Photographs. However, the March to the Moon catalogue at Arizona State University does not match these other two. The NASA catalogue idents the first image in the following sequence as AS15-95-12980, whereas the ASU catalogue uses 12983 for that image. In this journal, the NASA index numbering will be followed.
Although frame AS15-95-12980 is partially obscured, it manages to view some of the landscape near the Moon's south pole. Of particular note is Vallis Schrödinger, an enormous gash, 310 kilometres long, that cuts clean across Sikorsky crater on its way to a giant crater off the edge of the frame, also named after the Austrian physicist, Erwin Schrödinger, 1887-1961. Many of the craters towards the right of this frame have floors filled with mare-type material and are considered part of Mare Australe (Southern Sea), especially Lyot, named after a French astronomer, Bernard Lyot, 1897-1952.
AS15-95-12980 - Lunar terminator including Vallis Schrödinger - Image by NASA/Johnson Space Center.
AS15-95-12981 - Crater Humboldt - Image by NASA/Johnson Space Center.
The photographer, probably Al, takes a sequence of images across the width of the Moon just inside the terminator where the low-angle lighting shows the relief in the landscape.
AS15-95-12982 - View towards the lunar south pole including craters Beila, Nearch and Hagecius - Image by NASA/Johnson Space Center.
AS15-95-12983 - Eastern region including craters Beila and Pontécoulant - Image by NASA/Johnson Space Center.
AS15-95-12984 - Western Mare Australe including crater Oken - Image by NASA/Johnson Space Center.
AS15-95-12985 - Crater Humboldt - Image by NASA/Johnson Space Center.
AS15-95-12986 - North of crater Humboldt including crater Gibbs - Image by NASA/Johnson Space Center.
AS15-95-12987 - View towards the lunar north pole including crater Joliot - Image by NASA/Johnson Space Center.
AS15-95-12988 - View towards the lunar south pole including crater Boussingault - Image by NASA/Johnson Space Center.
AS15-95-12989 - Crater Petavius and Rima Petavius - Image by NASA/Johnson Space Center.
AS15-95-12990 - Crater Petavius and southwest Mare Fecunditatis - Image by NASA/Johnson Space Center.
AS15-95-12991 - Mare Smythii - Image by NASA/Johnson Space Center.
A composite of some of these images has been constructed.
Composition of images AS15-95-12982 to 12986, 12988 and 12991 showing the easter limb area including Mare Smythii, crater Humboldt and the view towards the south - Source images by NASA/Johnson Space Center.
Near the top of the image is Mare Smythii (Smyth's Sea), and Humboldt faces the camera near the middle, its dark patches easily visible.
AS15-95-12992 - Mare Smythii - Image by NASA/Johnson Space Center.
AS15-95-12993 - Cratered region centred at 49°S, 49°E including craters Biela, Watt and Steinheil - Image by NASA/Johnson Space Center.
AS15-95-12994 - View westwards at the lunar northern region centred at 44°S, 26°E including craters Metius, Fabricius and Nicolai - Image by NASA/Johnson Space Center.
In AS15-95-12995, Mare Fecunditatis is well framed showing the Messier pair of craters that the crew recently flew over, and the comet-tail rays that emanate westwards from them. The large crater that dominates the eastern side of the mare is Langrenus.
AS15-95-12995 - Mare Fecunditatis including craters Langrenus and Goclenius - Image by NASA/Johnson Space Center.
AS15-95-12996 - Craters Stevinus and Petavius - Image by NASA/Johnson Space Center.
Frame AS15-95-12996 looks directly down to an area of battered highlands southeast of Mare Nectaris. At lower right is Petavius, a large, flat-floored crater 177 km in diameter which is somewhat similar in form to Humboldt with its dark patches and a cleft, Rimae Petavius, which cuts across its floor. These features get their name from a French historian and student of chronology, Denis Petau, 1583-1682. Just right of centre is Stevinus, a 75-km crater named after Simon Stevin, 1548-1620, a Belgian mathematician. The small bright feature above it is Stevinus A. Centre left is the 70-km Rheita, named after Anton Maria Schyrleus of Rheita, a Czech astronomer who was a contemporary of Johannes Kepler.
[Download MP3 audio file. Clip courtesy National Archives and Records Administration.]
This is Apollo Control at 224 hours, 53 minutes. Apollo 15 now about 27 hundred [nautical] miles [5,000 km] from the Moon, and during the change of shift press briefing, we had one or two very brief exchanges with Dave Scott aboard the spacecraft. We'll play that for you now.
[Download MP3 audio file. Clip courtesy National Archives and Records Administration.]
224:57:29 Parker: And, 15; Houston. We'd like Gamma-ray Gain Step, On, up, three clicks. Over.
224:57:40 Scott: Okay. Gain Step, On, up, three clicks.
Long comm break.
This step is the termination of a ten-minute period of calibration for the Gamma-ray Spectrometer.
Flight Plan page 3-341.
About now, a change is made to the DAP (Digital Auto Pilot), a computer routine that maintains the desired spacecraft attitude, such that any corrections will be carried out at a slower rotation rate, namely 0.2°/sec instead of 0.5°/sec.
[Download MP3 audio file. Clip courtesy National Archives and Records Administration.]
225:04:07 Parker: Apollo 15, Houston. [Pause.]
225:04:14 Worden: Go ahead, Bob.
225:04:15 Parker: Roger. We'd like to move that "Verb 49 maneuver to lunar surface photo attitude" that you'll find at 225:30 in the Flight Plan. We'd like to move that up to 225:24. Over.
225:04:31 Worden: Roger. Understand; move the "Verb 49 maneuver" to 225:24.
225:04:36 Parker: Roger.
Very long comm break.
As they reach an approximate altitude of 3,600 nautical miles (6,700 km), their vantage point now permits them to see Tycho for the first time in the mission, as shown in AS15-95-12997.
AS15-95-12997 - Crater Tycho - Image by NASA/Johnson Space Center.
At about 100 million years old, Tycho is not only quite big, with a diameter of 86 kilometres and a depth of 4.5 km, it is also very young in lunar terms. This is borne out by the striking ray system which dominates the Moon's near side, and which is easily visible from Earth during a full Moon, even with the naked eye. The crater deservedly takes its name from one of the giants of pre-telescopic astronomy, Tycho Brahe, 1546-1601, whose careful visual measurements of the planetary positions laid a foundation for Johannes Kepler's analysis and conclusion that the planets moved in elliptical orbits, work which forms the basis for the trajectory mathematics that Mission Control now use to guide Endeavour on its journey.
Another mare caught in this sequence is Mare Marginis in AS15-95-12998.
AS15-95-12998 - Mare Marginis including craters Joliot and Neper - Image by NASA/Johnson Space Center.
Mare Crisium is well shown in AS15-95-12999. From Earth, we are used to seeing this mare heavily foreshortened along its E-W axis. In this picture, the viewpoint foreshortens its N-S axis instead, but it also suggests the truth that Mare Crisium is indeed elliptical in shape along its E-W axis. The ray crater, Proclus, is just to the left and its rays dust the western half of the mare surface.
AS15-95-12999 - Mare Crisium - Image by NASA/Johnson Space Center.
[Download MP3 audio file. Clip courtesy National Archives and Records Administration.]
225:25:26 Parker: Apollo 15, Houston.
225:25:31 Worden: Houston, 15. Go.
225:25:32 Parker: Ah, Rog. Be advised we'll be monitoring your maneuver here in case you get in your gimbal lock. And the High Gain [Antenna] angles [you should use] in case you lose antenna lock in the new attitude will be pitch of minus 45 and yaw of 024. Over.
225:25:54 Worden: Roger. Understand pitch minus 45 and yaw 024, if we lose it.
225:26:00 Parker: Roger.
225:26:01 Worden: And thanks for watching it for us, Bobby. [Long pause.]
Two possibilities are being catered for in Parker's advice. First, with respect to the current alignment of the guidance platform, there are attitudes the spacecraft should not go to for fear of reaching gimbal lock, a condition that disturbs that alignment, entailing a total realignment. The crew and controllers go out of their way to avoid this condition. Second, as they make their manoeuvre, it is possible that the control system of the HGA might not manage to keep the antenna pointed at Earth. As a precaution, appropriate angles are given which will allow the crew to re-establish the link.
225:26:21 Parker: And, 15, if one of you has time, I have a few more Flight Plan updates for you. [Pause.]
225:26:34 Worden: Okay, Houston. Stand by one. [Pause.] Go ahead, Bob.
225:26:42 Parker: Okay. The pitch and yaw angles for the P20 - P52 attitude at 226:00 is: pitch of minus 37; yaw of 322. [Pause.]
225:27:02 Irwin: Understand at the P52 attitude, it's pitch minus 37, yaw 322.
Al is about to realign the guidance platform. For this, the spacecraft will be manoeuvred to a specific attitude which avoids gimbal lock on both the old and new alignments. These HGA angles will allow the high quality S-band link to Earth to be reestablished at the new attitude.
225:27:08 Parker: Roger. At 226:15, we're changing that Verb 49 maneuver attitude to the following coordinates, 327, 143, 055. [Pause.]
225:27:37 Irwin: Roger. Copy the change to the Verb 49 maneuver that occurs at 226:15 to 327, 143 and 055.
This attitude is intended for the hour of the crew's meal break when the X-ray Spectrometer will be used as a simple X-ray telescope pointing, in this case, towards the constellation of Centaurus.
225:27:47 Parker: Roger; and the High Gain angles will be pitch 13, yaw 212. [Pause.]
225:27:58 Irwin: Roger. Pitch 13, yaw 212.
225:28:03 Parker: Roger. Stand by. [Long pause.]
225:28:15 Parker: And, 15, we're observing yaw of 61 degrees right now. [Long pause.]
225:28:40 Parker: 15, Houston. We have 65 degrees yaw.
Parker is advising Al that the spacecraft is approaching gimbal lock.
225:28:46 Worden: Rog, Bob. We're watching.
225:28:50 Parker: Okay, three more Flight Plan updates, Jim, if you're ready. [Long pause.]
225:29:05 Worden: Go ahead, Bob.
225:29:06 Parker: Okay, at 226:22, on - it'll be a line above the line that says "X-ray, On." The new line that will be added will be "X-ray, Off, for 1 second; then". Over. [Long pause.]
225:29:35 Irwin: Understand. The new line added above "X-ray, On", and it'll read "X-ray, Off, 1 second; then".
225:29:42 Parker: Roger, that's good. At 227:32, we'll add a line on top of the "Verb 48" line that says "X-ray, Standby". [Pause.]
225:30:01 Irwin: Rog. Understand. At 227:32, "X-ray to Standby."
225:30:06 Parker: Roger. And at 227:57, on a line with the Mass Spec. on it, we'll have - we'll change that "Discriminator, High" to "Discriminator, Low". [Pause.]
225:30:23 Irwin: Understand. "Discriminator, Low" instead of "Discriminator, High".
225:30:25 Parker: And that completes the update for now.
225:30:31 Irwin: Roger.
Very long comm break.
[Download MP3 audio file. Clip courtesy National Archives and Records Administration.]
This is Apollo Control at 225 hours, 38 minutes. Apollo 15 now 4,745 nautical miles [8,788 km] from the Moon; the spacecraft velocity almost matching the altitude - 4,700 feet per second [1,430 m/s]. And at the present time, the crew aboard Endeavour are photographing the lunar surface. At the same time, the instruments in Scientific Instrument Module bay, the Gamma-ray, Alpha Particle, and Mass Spectrometer are gathering background data to be used in calibrating the data gathered in lunar orbit. A little later this evening, the crew will be turning on the X-ray instrument in the SIM bay and that will looking at extragalactic X-ray source in the constellation Centaurus. We plan to put the crew to bed in a little over - or a litle less, rather - a little less than two and a half hours from now at 228 hours. At 225 hours, 39 minutes; this is Apollo Control, Houston.
Page 3-340 in the Flight Plan includes a diagram showing the field of view of the Moon at this time.
[Download MP3 audio file. Clip courtesy National Archives and Records Administration.]
225:44:43 Scott: Houston, Apollo 15.
225:44:46 Parker: Roger, 15. Go.
225:44:50 Scott: Rog. Do you have any best guess on MCC-5 yet - whether or not we'll have one?
225:44:58 Parker: Stand by. It's not going to be very large.
Mid-Course Correction 5 is an opportunity set aside to make a short burn to fine tune their trajectory towards Earth. If required, it will occur at about 238:46, just under 3 hours after they wake up tomorrow. As it turns out the velocity error will be so small that they will not bother with MCC-5.
225:45:03 Scott: Well, the question is whether or not we have to prepare for it. And we have another request. We'd like to reschedule the UV photos presently scheduled for 239:10 to some other time, primarily because of the stowage in here. We've got most of the UV equipment already stowed beneath the rocks in prep for the EVA, and - to go in and go out of the stowage container takes a fair amount of time. And we'd like to reschedule that if it's possible.
225:45:39 Parker: Rog. [I] assume you mean after the EVA?
225:45:44 Scott: Rog.
225:45:46 Parker: Okay. Stand by.
225:45:50 Scott: Okay. This is a - this is a crowded fellow up here.
225:45:55 Parker: You guys shouldn't have brought so many rocks back. [Pause.]
225:46:01 Scott: Well, I guess every once in a while we wonder. [Long pause.]
225:46:15 Scott: But we don't wonder very long. [Long pause.]
225:46:52 Parker: Okay, Davy. First of all, no problem. We can delay those UV photos until after the EVA. Second, right now midcourse 5 looks like 2 feet per second, and we do want to do it. Over.
225:47:11 Scott: Okay, thank you. That's a couple of quick answers; appreciate it. That - that will help us in our planning.
225:47:17 Parker: Okay. That is only a preliminary estimate on that midcourse 5 though.
225:47:24 Scott: That's okay. That tells us the difference between SPS and RCS kind of burns.
225:47:30 Parker: Oh; Rog. [Long pause.]
225:47:58 Parker: 15; Houston. One more thing if it's convenient.
225:48:04 Scott: Go ahead. [No answer.]
225:48:18 Scott: Go ahead, Bob.
225:48:19 Parker: Okay. At your convenience, we'd like to verify or check the Primary Accumulator fill valve, On, until the primary accumulator quantity - that's for the glycol loop - is up to 50 to 55 percent. This is the result of a review of the EVA checklist from tomorrow. It assumes that this has already checked and that we're at the 50 to 55 percent level, so we'd like this check - you could do it tonight when you're getting ready for sleep or something. [Pause.]
225:48:52 Scott: Okay, we'll do it right now. That's planning ahead.
225:48:57 Parker: Copy.
Comm break.
Photography of the receding lunar disc continues though it is difficult to pin down which sequence of photographs is being taken at a particular time. The Flight Plan calls for black and white magazine S to be used with a 250-mm lens but the Apollo 15 Index of 70-mm Photographs states that the 80-mm lens was used with this camera. The index also states that the last three images on magazine RR were taken using the 500mm lens. A close look at the images themselves brings up some inconsistencies with this.
The full-disk images on magazine RR are approximately the same size as those on magazine S. By virtue of the fact that we can see more of the Moon's near side in the S images, they were clearly taken substantially later than those on RR. Therefore, for the images to be about the same size on the film, those on S must have been taken using a longer lens. Perhaps the RR images were taken with the 80mm and the S images with the 250. Or perhaps it was 250 and 500 mm respectively. The tools to determine this are not available to this journal. In the meantime, all these full disk images from both magazines are presented here. First, three images from RR.
AS15-95-13000 - Receding Moon - Image by NASA/Johnson Space Center.
AS15-95-13001 - Receding Moon - Image by NASA/Johnson Space Center.
AS15-95-13002 - Receding Moon - Image by NASA/Johnson Space Center.
Next, seven images on magazine S. Having been taken well after the previous set, these images have Mare Serenitatis in view.
AS15-94-12863 - Receding Moon - Image by NASA/Johnson Space Center.
AS15-94-12864 - Receding Moon - Image by NASA/Johnson Space Center.
AS15-94-12865 - Receding Moon - Image by NASA/Johnson Space Center.
AS15-94-12866 - Receding Moon - Image by NASA/Johnson Space Center.
AS15-94-12867 - Receding Moon - Image by NASA/Johnson Space Center.
AS15-94-12868 - Receding Moon - Image by NASA/Johnson Space Center.
AS15-94-12869 - Receding Moon - Image by NASA/Johnson Space Center.
[Download MP3 audio file. Clip courtesy National Archives and Records Administration.]
225:50:28 Scott: Okay, Houston. Our Prim. Accumulator quantity is now about 51 percent.
225:50:34 Parker: Rog. We copy; thank you.
225:50:40 Scott: And we filled it from about 45 [percent].
225:50:43 Parker: Thank you. [Long pause.]
Sy Liebergot served as EECOM under Flight Director Milt Windler (the Maroon shift) during the Apollo 15 mission.
Sy Liebergot, from 2000 correspondence: "The accumulator is part of the Primary Coolant Loop which provided cooling for the cabin and electrical equipment, as well as the liquid cooling garment of the CSM EVA astronaut. The coolant was water ethylene glycol which was circulated by a pump. Essential to the coolant loop was a 'bump on the line' called an accumulator, the function of which was to absorb pressure surges, and thermal (heat) expansion and (cold) contraction of the glycol. So it was essential that it was not overfull to allow room for thermal expansion and not underfilled for thermal contraction. Too much glycol would create a hard system (high pump head pressure) and make the pump work harder. Too little fluid would cause the pump to cavitate (spin too fast). Hence the reason for keeping the accumulator at the necessary level."
225:50:56 Scott: And if you have any other goodies you think we ought to check over, might as well do it this evening.
225:51:03 Parker: Rog, Dave. That's the only goodie we came upon - Stan - Stand by. [Long pause.]
225:51:52 Parker: Okay, 15. That's the only goodie we had from the review of the EVA checklist for tomorrow. That - that's the only one we could find. An extra goodie that we'd like this evening sometime; if you fellows intend to use the vacuum cleaner - is for you to give us a cue when you turn it on, so we can check and watch the currents. They saw a funny on an AC bus - or an extra current load on an AC bus when they think you were using the vacuum cleaner then. They'd like to verify that by watching it again when you use the vacuum cleaner.
225:52:27 Scott: Okay. Well, we've been using it quite often on and off.
225:52:32 Parker: Okay. Just sometime when you use it, if you give us a cue as you turn it on, that would help. [Pause.]
225:52:44 Scott: Okay, I - I guess we don't see any need for it this evening. And we could check it out if you'd like...
225:52:50 Parker: No, no.
225:52:51 Scott: ...we cleaned up pretty well. The cabin's nice and clean and I...
225:52:56 Parker: Rog, Dave. No, that's just a callout. The next time you happen to get around to feeling dirty and want to use the vacuum cleaner, give us a call if you would please.
225:53:10 Scott: Okay. We'll do it.
Very long comm break.
This is Apollo Control. The UV photography, which Dave Scott requested we reschedule, is the ultraviolet photography of the, in this case of Earth, using the electric Hasselblad camera. This is an experiment being conducted to obtain ultraviolet photographs of both the Earth and the Moon to be used in study of planetary atmospheres among other things. And Scott mentioned that the equipment for that photography is stowed under the rock boxes. They've already gotten the cabin apparently set up for the EVA and requested that we reschedule it to some point after the EVA, when Al Worden will be going outside the spacecraft to retrieve the camera magazines from the SIM bay. And on taking a look at the Flight Plan, we reported to the crew there'd be no problem - would be no problem in rescheduling this to sometime after the EVA. CapCom Bob Parker also asked the the crew, at the next opportunity when they have the vacuum cleaner out to clean up the cabin, that they give us a cue. We're interested in watching the data here on the ground, the electrical data and seeing if some current flows that we've noticed previously from the spacecraft fluctuate as we've seen them fluctuate and we suspect that the fluctuations we've seen are caused by turning the vacuum cleaner on and off. We'd like to get a cue from the crew the next time they use the vacuum cleaner to see if, in fact, this is the case. At the present time Apollo 15 is 5,519 nautical miles [10,221 kilometres] from the Moon. And as the altitude from the Moon increases, the velocity continues to drop off; down now to 4,571 feet per second [1,393 metres per second].
Flight Plan page 3-342.
With the Trans-Earth Injection burn completed and the crew about to set the spacecraft rotating in the PTC (Passive Thermal Control) manoeuvre, it is time for the guidance platform to be realigned from the TEI REFSMMAT to the PTC REFSMMAT. As with all large realignments of the platform, this is a two-stage process.
In the first place, Al realigns the platform to the TEI REFSMMAT using P52 in the computer as usual. This orientation matched the attitude of the spacecraft during the TEI burn and, although it is now redundant, this first realignment allows the amount of drift since the last P52 to be measured, these figures being -0.015°, -0.027° and +0.004° in X, Y and Z respectively. For this and the subsequent P52, Al aims the sextant at star 11, Aldebaran, or Alpha Tauri; and at 16, Procyon, or Alpha Canis Minoris.
The second realignment aims to swing the platform around to an orientation called the PTC REFSMMAT which aids the setting up of the barbecue mode. This REFSMMAT was uplinked to the spacecraft just over an hour ago. In each case, Mission Control can watch the progress of the P52 by monitoring the DSKY (Display and Keyboard) read-outs.
[Download MP3 audio file. Clip courtesy National Archives and Records Administration.]
226:14:16 Scott: Houston, 15. Did you get the P52 numbers?
226:14:20 Parker: Rog. We have all your P52 numbers, Al. [Long pause.]
226:14:34 Parker: Al, we know that one of them wasn't five balls. [Pause.]
CapCom Bob Parker is teasing Al about the accuracy of his star sightings, but hasn't twigged that he's talking to Dave, and Dave isn't rising to Parker's bait.
226:14:43 Scott: Say again.
226:14:44 Parker: Rog. We noticed one of those didn't have five balls on it.
226:14:50 Scott: Rog. Did you get the torquing angles on both the P52's.
226:14:55 Parker: Rog. Yeah, we got them.
226:15:00 Scott: Okay. Thank you. [Long pause.]
As part of the P52 procedure, Al uses the computer/optics system to measure the angle between the two stars that he used. The angle is compared to the true angle to present Al with the difference. It is a matter of some pride to CMPs that this difference is zero (to within a hundredth of a degree) which presents 00000, or "five balls" on the DSKY display. Five balls and four balls one (00001) were equally common during the mission with four balls two (00002 or 0.02°) appearing only occasionally. This level of error is of no consequence.
During the double P52 just completed, Al got five balls the first time, and four balls two on the second attempt.
This is Apollo Control. At the present time Al Worden is completing a platform alignment, the Program 52. He's aligning the platform to a new set of coordinates provided by the ground and these coordinates will be used as an attitude reference by the...
226:15:55 Parker: And, Endeavour; Houston. Over. [No answer.]
Comm break.
226:17:18 Parker: Endeavour, Houston. Over. [Pause.]
226:17:24 Scott: Go ahead, Houston; Endeavour.
226:17:26 Parker: Roger. If one of you guys has time, we have what may or may not be the last iteration on troubleshooting the Pan Camera this afternoon. Over. [Pause.]
226:17:38 Scott: Okay. Have at it.
Mission Control are still concerned about the characteristics they saw from the Panoramic Camera's telemetry when it was supposed to run to the depletion of its film. Each time a problem appears in the spacecraft, a team in the SPAN (Spacecraft Analysis) Room begin dissecting and troubleshooting it, both to rectify it and to weigh up the possible consequences if it continues to impact the mission. The instructions Parker will read up are to put the camera through a well-understood set of steps so that its telemetry can be studied again.
226:17:40 Parker: Okay, step one; we'd like to know - you - you can give us these afterwards, but the first step is to determine the status of the Service Module Sector 1 AC 2, circuit breakers on panel 181. Those are three circuit breakers. Number two is to determine the status of the Pan Camera Mode switch. Number three, after these have been done, Pan Camera Mode, Standby; Power, On, talkback barber pole for 2 seconds, then gray, and then Stereo. Number four, Pan Camera Mode, Operate, talkback barber pole for 2 seconds, then gray. Number five, operate Pan Camera until MSFN cues, or until the beginning of the sleep period. And number six, on MSFN cue, Pan Camera Mode to Standby; and after one minute, Pan Camera Power, Off. Over. [Pause.]
226:19:07 Scott: Okay, Bob. You clipped the first part of number 5. Say again, please.
226:19:12 Parker: Roger. Number 5 says operate the Pan Camera until the ground gives you a cue or until the beginning of the sleep period. Then we'll give you a cue.
226:19:27 Scott: Okeydoke. Stand by a minute. [Long pause.]
226:19:55 Scott: Okay, Houston. SIM Sec AC 2 circuit breakers, three, Closed, verified. And the Pan Camera Mode switch is in Standby. So would you like us to go to step 3?
226:20:08 Parker: Endeavour, Endeavour, this is Houston. Roger. That appears to be the problem. Stand by and I'll see what we want to do. Do we... [Pause.]
226:20:23 Scott: Okay.
226:20:24 Parker: Apollo 15, Apollo 15, this is Houston. Roger. Press on with step 3 from that point when convenient.
Note that Parker has begun repeating the initial words of his call. As explained at 228:17:40, this is to overcome network communications problems. As pointed out by journal reader Dave Edwards, Dave Scott noticed about a minute ago that the beginning of Parker's sentences were being clipped. Parker immediately begins a work-around until the problem can be fixed.
226:20:35 Scott: Okay. Going Power, On, 2 seconds, gray, and then stereo. [Long pause.]
226:20:55 Scott: Okay. Power, On, and we have a continuous barber pole.
226:21:00 Parker: Apollo 15, Apollo 15. Roger. Understand, continuous barber pole.
226:21:08 Scott: Why don't you just tell us what next? Do you want to go to Stereo or not?
226:21:14 Parker: Apollo 15, Apollo 15, stand by.
226:21:19 Scott: Okay.
226:21:23 Parker: Apollo 15, Apollo 15, press on with Stereo, please.
226:21:30 Scott: Roger. It's Stereo now, still barber pole. [Long pause.]
226:21:49 Scott: And I guess we'll go to step 4 now. Okay?
226:21:52 Parker: Apollo 15, Apollo 15. Roger.
226:21:58 SCott: Okay. Operate, still barber pole.
226:22:09 Parker: Apollo 15, Apollo 15, Houston. Roger. We understand; it's still barber pole, and we'll give you a cue when to turn it off. Okay? Thank you.
226:22:17 Scott: Roger. Be standing by.
Comm break.
[Download MP3 audio file. Clip courtesy National Archives and Records Administration.]
226:25:37 Parker: Apollo 15, Apollo 15, Houston. Over. [Pause.]
226:25:46 Scott: Go ahead.
226:25:47 Parker: Apollo 15, Apollo 15, we've succeeded in using up the last of the film in the Pan Camera. You may now go Pan Camera Mode, Standby; and, after 1 minute, Pan Camera Power, Off, per step 6. Over.
226:26:02 Scott: Okay, understand. Pan Camera to Standby, and 1 minute, Off.
226:26:11 Parker: Apollo 15, Apollo 15, Roger. [Long pause.]
226:26:53 Parker: Apollo 15, Apollo 15, Houston. We're going to take down the network line here for 20 seconds. We'll be back up with you after that.
226:27:05 Scott: All righty.
Very long comm break.
Mission Control's analysis leads them to believe that a sensor switch within the Panoramic Camera is not being acted upon at film depletion. After return to Earth, it is found that the film is about 60 metres short, having been cut in the middle of the camera's penultimate frame by its retrieval from the SIM bay. Their suspicions fall on a capacitor after the flight when another camera experiences the same type of failure, which is found to be due to the capacitor. However, the situation is not so simple.
Often in engineering, designers will implement a particular function or feature to deal with a particular set of requirements, only to discover that their "design feature" operates in unforeseen ways when brought into the final model. This is the case with the Panoramic Camera. There is a switch that operates when the film nears depletion. After its actuation, it unintentionally inhibits the "Operate" control if the camera is placed in "Standby". The camera should have been left in "Operate" until film depletion, but no one was aware of the problem because the situation could only arise on a space-borne camera. Pre-launch configuration was such that this unusual condition never occurred.
[Download MP3 audio file. Clip courtesy National Archives and Records Administration.]
This is Apollo Control. Now Apollo 15 is now 8,200 [nautical] miles [15,200 km] from the Moon. And the crew should be in the midst of an eat period, and we plan to put them to bed at 228 hours, or about 1 hour from now. Prior to that, they'll put the spacecraft in a stable attitude and then start it rotating slowly so that it gets equal exposure to sunlight and darkness. This is to maintain the proper temperature equilibrium. Dave Scott inquired a while ago if we were planning to do midcourse correction 5, that's a midcourse opportunity at 238 hours, 46 minutes, and the Flight Dynamics Officer reported at that time that yes, we did plan to do midcourse correction 5 based on the preliminary data that we have, the preliminary tracking information. That burn will be about 2 feet per second which would be performed with the Reaction Control System thrusters.
Prior to their meal break, a lithium hydroxide canister was changed, with number 19 going into receptacle B and the exhausted canister 17 being stowed in compartment A4.
The spacecraft is manoeuvred to aim the X-ray Spectrometer at Centaurus and the instrument is switched on to it can collect data during their break. Jim and Al switch places as the subject of the Surgeon's study via their biomedical harness.
The X-ray source known as Centaurus-A is an elliptical galaxy which was found to emit heavily across the electromagnetic spectrum. Optically, it is well known for the large band of dust that distinctively crosses in front of it. It is now thought to contain an active supermassive black hole that emits a jet of high energy particles that is detectable in radio and X-ray sensors
Flight Plan page 3-343.
Mission Control leave the crew alone for the full hour to get on with their meal. Once that is over, the X-ray Spectrometer is switched off, its covers are closed and Al manoeuvres the spacecraft to the correct attitude to commence the Passive Thermal Control rotation.
[Download MP3 audio file. Clip courtesy National Archives and Records Administration.]
227:36:36 Parker: Apollo 15, Houston. Over. [No answer.]
227:37:00 Parker: Apollo 15, Apollo 15; Houston. Over. [Pause.]
227:37:12 Scott: Houston, 15. Go ahead.
227:37:14 Parker: Roger, 15. We see you maneuvering to PTC, and we're requesting that you not maneuver to PTC until the SIM bay covers are closed. I don't know whether they're closed at the moment or not. [Pause.]
227:37:33 Scott: Roger. They're closed up. [Pause.]
227:37:39 Parker: Understand. And if you fellows...
227:37:41 Scott: We're just following down through the Flight Plan.
227:37:44 Parker: Good. We weren't sure where you were. If you fellows are through eating, we have two or three calls to send up to you, when it's convenient. [Long pause.]
227:38:34 Parker: Apollo 15, Apollo 15; Houston. We can go to T-stop with the Mapping Camera now. And that would be - to follow the checklist on pages 1-39, steps - section 6, 7 and 8; first one being Mapping Camera, On to Off, 30 seconds, and then Standby. Over. [Long pause.]
227:39:23 Worden: Houston, 15.
227:39:25 Parker: Apollo 15, Apollo 15; Houston. Go.
227:39:28 Worden: Houston, 15. Okay...
227:39:31 Parker: Apollo...
227:39:32 Worden: ...Listen, Bob. Is this the T-stop on the Mapping Camera photo PAD at 224:10?
227:39:37 Parker: Apollo 15, Apollo 15, that's a Roger. [Long pause.]
The Mapping Camera PAD that Al refers to only had an absolute T-start time which had been read up at 222:49:49. The T-stop time was replaced by an instruction to stop the camera on the ground's instructions - a MSFN cue - which the ground have just given.
227:40:31 Scott: Okay, Houston. Go with the rest of the updates to the Flight Plan.
227:40:36 Parker: Apollo 15, Apollo 15; Houston. Roger. We - want to remind you, when you go into PC - TC, to follow the block in the Flight Plan for the usage of quads, rather than the section in - in the checklist where it calls out to disable all jets on two adjacent quads. This is to avoid contamination of the Mass Spec. It's just to remind you to follow that little box in the Flight Plan. Over.
The last time Al executed the PTC manoeuvre, was during the translunar coast, before the SIM bay door had been jettisoned. Now he has to be careful that the hot gases from the RCS thrusters do not impinge on these exposed instruments, therefore, he must follow steps in the Flight Plan rather than in the checklist.
227:41:07 Scott: You mean that little box on page 3-343?
227:41:12 Parker: Apollo 15, Apollo 15, that's a Roger.
227:41:17 Scott: Okay. We'll follow that little box just like it's in the Flight Plan. Go ahead with your - the rest of your updates.
227:41:23 Parker: Apollo 15, Apollo 15. Roger. On - one discussion here on the UV photos which we're delaying until after the EVA, it looks like the last chance to get these photos is at 246 dash 15, which is about 3 or 4 hours after the nominal end of the EVA. We'd like to propose that for your consideration. Over.
At 225:45:03, Dave requested that a series of UV photos be delayed as the equipment had been stowed beneath other items in preparation for tomorrow's EVA.
227:41:51 Scott: That's just fine. We'll do it, 246:15. Thank you. [Long pause.]
227:42:29 Scott: Okay, Bob. Do you have anything else to add to the Flight Plan.
227:42:34 Parker: Apollo 15, Apollo 15; Houston. Roger. One more item we just got is a request that now that the covers on the X-ray are closed, we're requesting X-ray, On, for 10 minutes and then Off. Over.
227:42:51 Scott: Okay, X-ray, On, for 10 minutes and then Off. [Pause.]
227:42:57 Parker: Apollo 15, Apollo 15, the posit - the last [switch] position should be Standby rather than Off. Over. [Pause.]
227:43:07 Scott: Roger. Standby. [Long pause.]
227:43:52 Scott: Okay, Houston. The X-ray is On, and we'll turn it Off in 10 minutes. Anything else?
227:44:00 Parker: Apollo 15, Apollo 15; Houston. That's a Standby in 10 minutes. I believe you understand that, Dave, anyway. And I believe that the next...
227:44:11 Scott: Rog.
227:44:12 Parker: ...thing we will want from you is a call when you're ready to go to sleep. And we will verify all systems at that time so we can get a solid goodnight, rather than tagging on, again like last night. [Pause.]
227:44:27 Scott: Roger that.
Comm break.
[Download MP3 audio file. Clip courtesy National Archives and Records Administration.]
227:46:29 Parker: Apollo 15, Apollo 15; Houston. We see you cycling through the DAP. We suggest you need a zero in R2 to get B/D roll. Over.
Very long comm break.
The status of the Digital Auto Pilot is set by two values stored in registers in the computer. Mission Control is monitoring Al's use of the DSKY and they help to catch any problems with setting the PTC roll going. The alternative steps given in the Flight Plan for this PTC include the use of the B and D RCS quads to start the roll. This pair of opposed quads are chosen as they direct their exhaust away from the SIM bay. They are enabled by entering 0 in the first position of Register 2 in the DAP routine.
[Download MP3 audio file. Clip courtesy National Archives and Records Administration.]
This is Apollo Control at 227:55 minutes. The crew is - aboard Apollo 15, is presently getting the spacecraft set up for the Passive Thermal Control where they'll be rotating at about 3 revolutions per hour. This is the standard set up used during the sleep periods to maintain proper thermal equilibrium on the spacecraft. And at the present time, Apollo 15 is 10,488 nautical miles [19,424 km] from the Moon. The spacecraft's velocity is 4,129 feet per second [1,259 m/s]. We're going to replay the videotape from this morning's check of the TV system on the Lunar Roving Vehicle at the Hadley Base site. The total tape duration is about 12 minutes.
227:57:08 Worden: Houston, 15.
227:57:11 Parker: Apollo 15, Apollo 15. Go.
227:57:16 Worden: Hey, Bob, you didn't update the [garble] load in the P20 for PTC. Was that meant to be updated to .375 or shall we leave it at .35? [Pause.]
On the first day of the mission, Al had some trouble getting a stable PTC roll going. One of the changes given by Mission Control to fix the problem was to make the spacecraft spin slightly faster, at 0.375°/second.
227:57:33 Parker: Apollo 15, Apollo 15. Let's keep it at .375.
227:57:40 Worden: Understand you want the Flight Plan updated to .375.
227:57:46 Parker: Apollo 15, Apollo 15. That's a Roger.
227:57:53 Worden: Roger. Thank you. We got the update. [Long pause.]
227:58:46 Irwin: Houston, Apollo 15.
227:58:48 Parker: Apollo 15, Apollo 15; Houston. Go ahead.
227:58:54 Irwin: Yes, Bob. We're trying to retract the Mapping Camera. But the time has been well exceeded and we still have the barber pole indication. [Pause.]
227:59:06 Parker: Apollo 15, Apollo 15. Stand by. [Long pause.]
The first time the Mapping Camera was used in lunar orbit, its extension and retraction times were as expected. Subsequently, the times have extended until now when the mechanism appears to be stuck in the deployed position. This is not a problem for the remainder of this mission but needs to be fixed before Apollo 16, in case a similar problem affects spacecraft operations.
227:59:59 Parker: Apollo 15, Apollo 15. We'd just as soon you didn't spin up quite yet. We still think the rates are a little high. Over. [Pause.]
228:00:14 Worden: Okay, Houston. We'll wait on your cue then.
Comm break.
Flight Plan page 3-344.
The crew's rest period is due to begin now.
228:01:34 Parker: Apollo 15, Apollo 15; Houston. Concerning the Mapping Camera retraction problem, the question is did you get a barber pole during the Alpha/X-ray cover procedure? Over. [Long pause.]
228:02:03 Irwin: You ought to amplify your question there a little bit, Bob. You mean when we are - operating the covers? [Long pause.]
228:02:35 Parker: Apollo 15, Apollo 15; Houston. Jim, the question basically is, did the barber pole, did the talkback function properly when you just closed the alpha/X-ray covers? Over. [Pause.]
228:02:52 Irwin: Yes. Dave said it works fine. [Long pause.]
228:03:43 Parker: Apollo 15, Apollo 15; Houston. Jim, stand by on that. We got your last answer, and they're working on it.
228:03:53 Irwin: Okay. I think I'll take the - go out of the Retract position on the switch and just wait for your word.
228:04:01 Parker: Apollo 15, Apollo 15. That sounds good to me, Jim.
Long comm break.
Mission Control suspect that there is mechanical interference between the camera and the instrument covers. Al will have a chance to look at it tomorrow but, in the meantime, the SPAN room continues to troubleshoot the problem. However, the problem still had not been solved according to the post-mission report dated 5 months after the flight.
[Download MP3 audio file. Clip courtesy National Archives and Records Administration.]
228:09:45 Parker: Apollo 15, Apollo 15; Houston. We'd like to hold off on PTC a little bit longer until we get this Mapping Camera business straightened out. And, Jim, for some troubleshooting on this, we'd like to have you check on panel 181, the Main A circuit breaker, Closed, and the Deploy/Retract switch in the Retract position. And on panel 278, the Deploy Main A circuit breaker, Closed. Over. [Pause.]
228:10:26 Irwin: Those two circuit breakers and the switches are verified, Bob, Closed.
228:10:32 Parker: Apollo 15, Apollo 15. Copy. [Pause.]
It's getting past the time for the crew's rest period to start and they are getting on with the items in the pre-sleep checklist. First of all, Jim reports on the crew status and the onboard read-outs.
228:10:40 Irwin: And the presleep checklist: been no medication today. Onboard readouts are Bat C, 37; pyro Bat A, 37.3; pyro Bat B, 37.3. On the RCS, it's 56, 55, 54, and 55. And I guess, after we get PTC squared away, we'll give you the E-memory dump. [Pause.]
It is interesting to compare the RCS quantity readings from the spacecraft, currently averaging 55 percent, to those coming from Mission Control which were averaging 46 percent this morning and will be 41 percent tomorrow morning. This is in light of the fact that the secondary tanks were brought online earlier today, giving an accurate data point of 43 percent. Mission Control have far greater resources to monitor and factor helium temperature, pressure, RCS usage and system history into an accurate reading, whereas the read-out in the CM is derived only from the temperature and pressure of the helium used to pressurise the system.
228:11:12 Parker: Apollo 15, Apollo 15; Houston. Copy the crew status and the onboard readout. And stand by on the E-mod; we may ask you for that before PTC, but we'll be back with you on that in a minute.
Comm break.
Other items to be dealt with are to chlorinate their water supply, verify the status of various spacecraft systems and prepare the spacecraft communication system for their sleep period.
[Download MP3 audio file. Clip courtesy National Archives and Records Administration.]
228:12:48 Scott: Houston, 15. [Pause.]
228:12:56 Parker: Apollo 15, Apollo 15; Houston. Go.
228:13:02 Scott: Rog. Un - unless you got a solution for the camera now, why don't we troubleshoot it in the morning and get on with our evening powerdown. Okay?
228:13:13 Parker: Apollo 15, Apollo 15; Houston. That's a Roger. We've just come to that conclusion ourselves down here. We're ready for an E-mod dump before the start of PTC, please. [Pause.]
228:13:29 Scott: Okay. It's on the way. [Long pause.]
228:14:18 Parker: Apollo 15, Apollo 15; Houston. One last attempt on the Mapping Camera. We suggest you try Mapping Camera doors, Open, then Retract, and then doors, Close, if successful on the retract. And you can do that while - after you start up PTC, if you like.
228:14:38 Scott: Roger. We've already attempted to do that, Bob.
228:14:43 Parker: Apollo 15, Apollo 15; Houston. Roger. You're ahead of Building 45. [Pause.] And, Apollo 15, Apollo 15, we have a good E-mod dump. [Long pause.]
The E-mod dump send the contents of the computer's erasable memory to Earth so that its contents can be analysed overnight.
228:15:11 Worden: Houston, 15. How do the rates look now?
228:15:16 Parker: Apollo 15, Apollo 15; Houston. Your rates look good. You're Go for PTC.
228:15:23 Worden: Okay. We'll try. [Long pause.]
See the explanation of the PTC manoeuvre from earlier in the mission.
228:15:46 Parker: Apollo 15, Apollo 15; Houston. As soon as you configure the Mass Spec - Multiplier, Low; Discriminator, Low; Experiment, On; Ion Source, On; et cetera, you're Go for sleep. Then no more comments from the ground until morning.
Four hours ago, the boom carrying the Mass Spectrometer was deployed and the instrument allowed to outgas. Now it is operated throughout the rest period before being switched off just prior to tomorrow's EVA. The data gathered during this spell is primarily intended for comparison with that taken from lunar orbit in a bid to tease out indications of a lunar atmosphere.
228:16:08 Scott: Roger. [Pause.]
228:16:16 Parker: Apollo 15, Apollo 15, Houston is out for the evening. [Pause.]
228:16:25 Scott: Don't go too far out, though. [Pause.]
228:16:31 Parker: Apollo 15, Apollo 15, our ever watchful eye will be on you while you sleep.
228:16:39 Scott: Very good. [Pause.]
228:16:43 Worden: Houston, 15. [Garbled] initial rates [garbled]. [Long pause.]
This is Apollo Control. The spacecraft now is beginning the Passive Thermal Control rotation. As we rotate from one antenna to another on the Omni antennas, we'll pick up some noise from time to time during the evening.
228:17:12 Parker: Apollo 15, Apollo 15; Houston. You called just as we lost and locked onto the high - onto the Omni. [Pause.]
228:17:24 Worden: Okay, Bob. Just wanted to know how initial rates of PTC looked? [Pause.]
228:17:31 Parker: Apollo 15, Apollo 15, initial rates look good. We'll be keeping an eye on it though for you, Al.
228:17:40 Worden: Okay, Bob. It just didn't look like I got quite as much rate when I entered on that as I expected.
Very long comm break.
[Download MP3 audio file. Clip courtesy National Archives and Records Administration.]
Our Communications Engineer reports that the crew has configured - have configured the communications circuits on board the spacecraft now for their sleep period and we do not expect to hear from them further during this 8-hour rest period. We've had some questions [from journalists] on the double calls, the repetition of the call Apollo 15, by the CapCom. And the Network Controller reports that this is being done because of a weak or low level we've got on the landlines from Houston to - to Madrid. And normally the tone that is sent out in conjunction with the CapCom's call, the bleep that usually precedes the call is used to key the ground transmitter so that it's in the proper configuration for uplinking the voice communications. The problem we're having with the lines gives us a low level at Madrid and the beep is not getting through. At least not with sufficient signal strength to the transmitter to key the transmitter. So, in order to key it, the CapCom reports - repeats the call Apollo 15. The first Apollo 15 keys the transmitter and the second one goes up to the spacecraft. This is a relatively minor problem; the network controller says it can be readily remedied once we've completed our presleep checklist and have gotten the crew off to - off to sleep and don't expect any further air to ground communications. They'll simply take the line down, make the necessary corrections to it, and within a matter of minutes have the situation remedied. It was decided to use the so-called manual keying technique with the CapCom repeating the Apollo 15 call, simply because it was a simple procedure and because we were close to the - to beginning the sleep period when we could do the maintenance on the lines that were necessary. Apollo 15 at the present time is eleven hundred - rather 11,534 nautical miles [21,454 km] from the Moon and the spacecraft velocity is 4,078 feet per second [1,243 m/s]. The crew reported, prior to beginning their rest period, that the Mapping Camera, which extends out from the SIM bay on a rail system, had not, apparently, not retracted. They have an indicator in the spacecraft cockpit that tells when this camera has retracted and the indicator showed that it had not come back in. After checking with the - the situation with the Orbital Science Officer, it was decided that it would do no serious harm to leave the camera deployed. The only concern would be that the temperatures could possibly go higher than desired. However, the temperatures that we've seen from the Passive Thermal Control mode previously indicate that this should not be a problem; we would not expect the camera to become too warm and more importantly the film cassette. And the thermal experts feel that the temperatures that we'd encounter in the SIM bay during the Passive Thermal Control mode would not cause us any problem. So we've elected to follow the suggestion of Dave Scott and leave the camera deployed until tomorrow and work on the problem then. One suggestion that the Orbital Science Officer had is that perhaps the camera retract mechanism has become too cold and is for that reason failing to retract and perhaps in the Passive Thermal Control mode, when the temperature will warm up somewhat, it'll free whatever it is, that is causing the problem, and we'll be able to retract it in the morning. At 228 hours, 24 minutes; this is Apollo Control, Houston.
[Download MP3 audio file. Clip courtesy National Archives and Records Administration.]
228:41:49 Parker: Apollo 15, Houston. Over. [No answer.]
228:42:28 Parker: Apollo 15, Houston. Over. [Long pause.]
228:43:03 Worden: Houston, 15. Go.
228:43:06 Parker: Roger, 15. Would you believe that we have one more call on the Pan Camera. We do not show Pan Camera Power to Off, please, and unfortunately, that means that we might heat up the film too much. So we would like Pan Camera Power to Off. [Pause.] And guys, as long as you're down there, would you mind trying Mapping Camera, Retract once more. [Pause.] 15...
228:43:37 Worden: Sure.
228:42:38 Parker: ...we see a certain rise in temperature there which may mean that if it was frozen; it'll improve. And we do not see any - the Mass Spec. configuration yet. And a progress report on your PTC says it's about 60/40, but it'll - it will last the night.
Long comm break.
[Download MP3 audio file. Clip courtesy National Archives and Records Administration.]
228:48:17 Scott: Houston, it doesn't look like the Mapping Camera is going to come back in. What's the problem if it's left out?
228:48:24 Parker: 15, Houston. Would you believe we've just determined that it doesn't seem to be a problem if it stays out overnight.
228:48:35 Scott: Great. Then I guess we can call it quits for the night. Okay?
228:48:40 Parker: I sure hope so.
228:48:44 Scott: [Laughter.] Okay, good night.
228:48:46 Parker: 15, we don't have TM on you right now. Is the Mass Spec. taken care of?
228:48:54 Scott: Rog. The Mass Spec's taken care of. There's one switch out of position. And the Mapping Camera is going to go to Off. [Pause.]
228:49:11 Parker: Roger. Copied, Dave. We'll try again. [Pause.]
228:49:19 Scott: Okay.
Long comm break.
[Download MP3 audio file. Clip courtesy National Archives and Records Administration.]
228:58:50 Parker: Apollo 15, Houston. In the blind, no need to reply. Our Pan Camera data still shows Power, On. This is the middle switch in the bottom row. The Power Boost switch should be in the center, Off position. No need to reply. Over.
Very long comm break.
[Download MP3 audio file. Clip courtesy National Archives and Records Administration.]
This is Apollo Control at 229 hours, 30 minutes. The Flight Surgeon reports that the crew appears to be getting to sleep at this time. We have biomedical data on Command Module Pilot Al Worden and his rates indicate that at least he is approaching sleep. Apollo 15, at the present time, is 14,244 nautical miles [26,380 km] from the Moon and the velocity is down now to 3,976 feet per second [1,212 m/s]. During this rest period we plan to come up with hourly status reports and in the - in between status reports we will have lines down with tape recorders running to record any unexpected conversation with the crew. The spacecraft is in a stable Passive Thermal Control attitude right now. That will be one of the activities here in Mission Control tonight, to watch that attitude and see that it does not diverge from acceptable limits. And assuming that the attitude stays stable, the spacecraft rotating at approximately 3 revolutions per hour and not diverging from the preset attitude, we would not plan to call the crew this evening. At 229 hours, 32 minutes; this is Apollo Control.
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