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Day 6 part 27: Tracking, snapping and napping Journal Home Page Day 6 part 29: Going back to Houston

Apollo 10

Day 6 part 28: Snoopy and fuel cells cause concern

Corrected Transcript and Commentary Copyright © 2016 by David Woods, Robin Wheeler and Ian Roberts. All rights reserved.

Last update: 2019-05-19

Rev 29 attitude diagram

Planned spacecraft attitudes during rev 27.

(Click on above diagram for larger image.)

[131:15:-- Begin lunar Rev-29]

Flight Plan

Flight Plan diagram

131:17:XX PAO: This is Apollo Control at 131 hours, 17 minutes. We've had Loss Of Signal now as Apollo 10 has gone behind the Moon on the 28th revolution. We'll be reacquiring the spacecraft again in about 41 minutes at - as it is moving into the 29th revolution after it has begun the 29th rev. And on that revolution, we'll have our first look at lunar landing site 3, hopefully. We have a television transmission scheduled which will include the landing site in the central bay of the Moon. The crew will also be taking oblique strip photography of that landing site. During the change of shift briefing, we had no further conversation with the spacecraft. The crew is still sleeping. They have now been in that sleep period - sleep period for a little over 2 hours. At 131 hours 18 minutes, this is Apollo Control.

131:55:02 Stafford (onboard): What time?

131:55:11 Stafford (onboard): [Garble] 55. Time to [garble].

131:55:55 Cernan (onboard): [Garble] came through.

131:55:57 Stafford (onboard): Yes. How are you feeling?

131:56:01 Cernan (onboard): Feel great [garble] water.

131:56:08 Stafford (onboard): You had nearly 3 hours.

131:56:17 Cernan (onboard): I really feel good.

131:56:48 Cernan (onboard): No. No.

131:57:XX PAO: This is Apollo Control at 131 hours, 57 minutes. We're now less than a minute from reacquiring Apollo 10 on its 29th revolution of the Moon. The crew has been in a rest period for about 3 hours and if they are not awake on their own accord as we reacquire the spacecraft, we'll put in a call to the crew and awaken them. We have scheduled on this revolution photography and hopefully television of lunar landing site 3. We'll be standing by to hear from the crew in about 30 seconds now.

131:57:04 Stafford (onboard): [Garble] your intercom. Suit power on?

131:57:20 Cernan (onboard): In ICS/PTT? [Internal Communication System / Push To Talk.]

131:57:22 Young (onboard): Oh. I never turned that off. Did you turn it off, Tom?

131:57:27 Stafford (onboard): No.

131:57:30 Young (onboard): Something weird - weird thing happened. We [garble] today?

131:57:36 Stafford (onboard): Let's see. It's daytime out there now, though.

131:57:38 Young (onboard): Is it?

131:57:41 Stafford (onboard): Yes.

131:57:42 Young (onboard): Shall I get off a few quick photos of opportunity? Did we miss any? There anything out there left to be photographed? (Laughter)

131:57:52 Cernan (onboard): [Garble] I don't think so.

131:57:55 Stafford (onboard): Oh, shit. I've never seen that before.

131:58:00 Young (onboard): Yes, it's old - Are we going backwards?

131:58:15 Stafford (onboard): Wouldn't be surprised.

131:58:20 Young (onboard): Hey, I know we're a damn sight closer over here on the back side than we are on the front side. I think we better get the hell out of here before this thing - starts to take a nosedive for it.

[The lunar orbit of the Apollo 10 spacecraft was affected by the mass-concentrations (mascons), discovered during the Lunar Orbiter missions. The lunar gravitational potential is not constant, and in many areas the gravitational attraction is up to 0.5 % above or below the average. Many of the mascons are co-incident with many lunar basins such as Mare Crisium and Mare Nectaris and in this situation are believed to be due to the great thickness of dense basalt that forms the mare. These gravitational variations perturb the orbit of spacecraft, reducing the perilune and elevating the apolune. After these perturbances were discovered during the Lunar Orbiter missions, they were better defined during Apollo 8 so that a reasonably accurate model, known as R2, was developed for prediction of the Apollo 10 lunar orbit. The R2 model accounted for most orbit perturbations except those which tended to rotate the orbit plane. The change to the spacecraft's orbital plane resulted in the ground track for Apollo 10 passing about 5 miles south of landing site 2.]

[Young is aware of how the orbit is being perturbed and feels the time had nearly come for Apollo 10 to leave lunar orbit, before the low point of it's orbit gets too close to the lunar surface.]

131:58:31 Young (onboard): Don't you - don't you think we're closer back here?

131:58:34 Stafford (onboard): Could be.

131:58:35 Young (onboard): You could make some scientific measurements, but it would just screw everything up.

131:58:38 Stafford (onboard): Yes.

131:58:43 Cernan (onboard): Hold it there [garble].

131:59:XX PAO: Capcom Joe Engle is getting ready to put in a call to the crew.

Air-to-ground audio

131:59:09 Stafford: Hello, Houston. Apollo 10.

131:59:15 Engle: Hey, good morning, Apollo 10. How are you doing this morning?

131:59:19 Stafford: Oh, just woke up from that little nap. Pretty good. We had kind of a long day.

131:59:26 Engle: Roger that, Tom. What have you got there for the crew status? When you get a chance, we're standing by for that.

131:59:38 Cernan: It was just a nap, Joe.

131:59:47 Cernan: As I look around here - this is Gene Cernan calling from the Moon - As I look around there's three of us: John Young, Tom Stafford, and myself. And their status has been fairly confident. Can we help you?

Flight Plan

Flight Plan diagram

132:00:07 Engle: OK. You got me.

132:00:30 Engle: OK. 10, this is Houston. We're standing by for some TV on this pass, and I've got some PADs to update to you. I've got a maneuver PAD and a couple of map updates, and as soon as you get a chance we would like to have a crew status as per the Flight Plan, there.

132:00:50 Stafford: OK. Nobody has taken any of the little pills, and we'll read you out some RADs in a minute. Over.

132:00:54 Engle: Hey, that'll be fine. Thank you, Tom.

132:00:59 Cernan: Go ahead with the maneuver PAD. Let's get that one out.

132:01:03 Engle: OK. You're ready to copy?

132:01:23 Cernan: Yes, Joe, I am. Go ahead.

132:01:26 Engle: Okey doke. This is for TEI-30, SPS/G&N; on your Noun 33, it's 135:37:18.45; plus 35111, plus 00049, plus 01010; pitch 054, all else is NA, and I'll stand by for the readback.

132:02:07 Cernan: OK. TEI-30, SPS/G&N; 135:37:18.45; plus 35111, plus 00049, plus 01010; pitch is 054, and if you didn't get Noun 31, it's 135:37:18.45.

[The TEI-30 PAD is interpreted as follows:

Purpose: The PAD is a revised version for an emergency burn to return to Earth at the end of Rev-30.

Systems: The burn would be made using the SPS engine, under the control of the Guidance and Navigation system.

Vehicle weight (Noun 47): NA

Pitch and yaw trim (Noun 48): NA

Time of ignition (Noun 33): 135 hours, 37 minutes, 18.45 seconds.

Change in velocity (Noun 81), fps (m/s): X, +3,511.1 (+1,070.2); Y, +4.9 (+1.5); Z, +0101.0 (+30.8).

The large positive number in the X direction implies a large prograde component, essentially adding to their orbital velocity, exactly what would be expected from an escape maneuver. The value is also very similar to the Moon's velocity in its orbit around Earth. With this in mind, a way to think of the TEI burn is that it counters the Moon's orbital velocity, bringing the spacecraft almost to a stop with respect to Earth. When this happens, the spacecraft begins to fall to Earth while the Moon continues to move away in its orbit, sliding out from beneath the spacecraft.

Spacecraft attitude (IMU angles): Roll, NA; Pitch, 5.4°; Yaw, NA.

Two RCS jet ullage for 14 seconds.

All the subsequent items on the form are not applicable to this maneuver.] 

132:02:49 Engle: OK, Gene-o. We copied that, and if you'll give us the computer, we'll send the state vector up to you.

132:05:43 Cernan: Hey, Joe. Are you ready to pick up High Gain at this time on TV? We're on the air.

132:05:51 Engle: That's affirmative. We're all ready for it, Gene-o.

132:05:56 Stafford: OK. Are you finished with the computer? I need to get the Verb 83.

[Verb 83 is used as part of Routine 31 to Request Rendezvous Parameter display No.1. In the context it is being used for at this time, Stafford is looking for the CMC to display the angle between the CSM plus-X axis and the local horizontal plane at the current time. It is displayed from 0 to 360 degrees to the nearest 0.01 degree. This value is updated every 2 seconds. He wants this value to try to establish the CSM relative attitude when he sights the descent stage of the LM Snoopy. He can pass this information along with the time of the sighting MCC-H, to assist them to estimate the current orbit of the LM descent stage.]

132:06:01 Engle: Roger. We're all done. You can have it back, Tom.

132:06:31 PAO: You have heard Gene Cernan advise that the crew is transmitting television, and we should be receiving that shortly. At the present time, we're still standing by to get a lock on the High Gain Antenna.

132:07:11 Young: Houston, Apollo 10. Over.

132:07:15 Engle: Roger. Go ahead, 10. Houston.

132:07:19 Young: Roger. That's Neper crater right there. You see it?

132:07:22 Engle: No. We're not getting a - Yes, there we go. OK. You bet.

Television coverage from Charlie Brown.

TV transmission (303MB MP4 video file)

132:07:28 PAO: We've got a black and white picture. Still waiting for the color.

132:07:34 Engle: Roger. It's coming in real good now, John. It's right in - just about in the center of our screen.

132:07:42 Young: OK. Well, this is another crater, here, I just panned down to.

132:07:49 Stafford: What does the color look like, Joe? Again, the lunar surface is tan except Neper is more of a dark brown; and again, the new areas look more like gypsum, like whitish - chalky white. Over.

132:08:03 Engle: Yes, it's just the way it looks down here, Tom. And at the top of your - At the top of your picture, just a moment ago, we had a darker, looks like a mare area up there.

132:08:12 Young: Yes. That's the crater in...

132:08:25 Young: Roger. That is a mare area with a central peak.

132:08:28 Engle: Roger. That central peak really stands out, John.

132:08:32 Young: Yes, and it's white on the bottom and sort of - sort of black-gray on the top. And then there's some white up at the top of it.

132:08:45 PAO: Apollo 10 is about 54 miles [100 km] high.

132:08:47 Engle: Those colors are coming through just as you're describing them. We've got that tannish color, kind of a grayish-tan color and the mare area comes out dark black and the white areas – just like you say, Tom, they look just like gypsum.

132:09:02 Young: There's a really bright rayed crater. Little bitty one. Bit...

132:09:22 Young: I don't know if you can see it or not, but it's that white crater in the center of your screen?

132:09:27 Engle: Roger. We got it.

132:09:28 Young: [Garble] small one. It has a black spot right in the middle of it. OK. It has a black spot right in the middle of it. That's a very small impact crater, very - I don't know whether it's an impact crater or not, but it's very new. It looks new.

132:09:44 Engle: OK. You're talking about the fairly small one, are you not, John?

132:09:50 Young: Yes. It's very tiny. Just a white spot.

132:09:56 Engle: Yes. I think we got the one you're referring to; however, we can't see the spot in the center of it. We don't have quite that good a definition.

132:10:05 Young: Roger. Here's another bright one inside of a rather larger crater with a little darker - little darker brownish-type bottom on it.

132:10:14 Engle: Yes. We get the spot...

132:10:15 Young: [Garble] over on the side it has two, you don't have the two dark spots in the center of it.

132:10:23 Engle: What is that white spot? Is that a small crater on the side of it there?

132:10:29 Young: Roger. That's a small impact crater. If you're seeing the same thing I'm seeing on the monitor, why you’re not - I don't imagine it would be terribly easy to tell what all is going on out there. But, it's a pretty good picture, all things considered, from how far it's going.

132:10:49 Engle: We've got a real good picture down here, John. And - Yes, that little white crater on the left-hand wall there stood out real well, and the craters that you're showing us now; looks as though you've got a central peak in one of those. Let's see if we can figure out which ones they are, there.

132:11:06 Young: Roger, look at that hill over there on the horizon.

132:11:11 Engle: Roger.

132:11:14 Young: I'll sort of pan - I'll pan the horizon, here, and you can see that this is not a very flat Moon. Look at all these - That's actual hills you're seeing out there, and they really stick up. And we just saw Snoopy rising. Maybe you can see it in your picture.

132:11:38 Engle: We can't see him. Whereabouts in the picture is he now, John?

132:11:45 Young: He's just right behind us, but he's not very far back there.

132:11:48 Engle: OK. Hey, which way are you - are you looking now, John?

132:11:57 Young: We’re going backwards right now.

132:12:07 Young: OK. Here's sweeping the other side of the horizon. No matter where you look on the Moon, there's always some different geological structure to study. Boy, it's really got its share of them! Now, we're coming to a place where the mare is getting darker. And, I don't know if you can tell it from this picture here, but there are a couple of spots in the middle there, that stand out as better, evidently much blacker than the - than the actual mare.

132:12:40 Engle: Yes. We got them. Those look pretty darn interesting.

132:12:49 Stafford: Hey, Apollo - Houston, this is Apollo 10. Look, I know you ran some studies, but by golly, we can see Snoopy, and he isn't too far away! He's catching up with us. Can you talk to the FIDOS? He's right down below us. We can occasionally see him tumbling end-over-end down below there, and he's coming in closer each pass. That's Snoopy's descent stage. We can see him right down below us now, and he's right - I thought he was a little out-of-plane, but now he's looking more in-plane with us.

132:13:22 Engle: OK. That's real interesting, Tom. We'll try and get FIDO on that.

132:13:58 Engle: Apollo 10, this is Houston. John, are you looking out directly east now, or were you looking directly east there?

132:14:07 Stafford: We're looking backwards.

132:14:10 Engle: Yes. OK.

132:14:14 Stafford: Snoopy is behind us. But we're going BEF.

[BEF-Blunt End Forward. The CSM is travelling with the crew looking back along the orbital path they have just past over.]

132:14:21 Engle: Roger, Copy.

132:14:25 Stafford: Yes, we're looking back east and Snoopy’s back there and evidently, he - earlier we saw him, and he was out in front of us and going above us and now he's behind us; but he's right around in our area, I'll tell you.

132:14:40 Engle: Can you estimate at all about how far below you think he is, Tom?

132:14:49 Stafford: No. We've lost him down in the maria now.

132:14:59 Engle: What kind of a pitch angle are - were you looking at him, do you think when you - when you last saw him, Tom? Some local or horizontal?

132:15:06 Stafford: Yes. We're looking, oh, about - We were looking straight out at about 215.

132:15:24 Stafford: It's taking forever for Verb 83 to come up here.

Air-to-ground audio

132:15:55 Stafford: Originally, we thought he might be out-of-plane, but that sure didn't look much out-of-plane to me where we finally saw him. He's getting awfully close. You could see the silver panels and - There he is right down below us; he's cutting across the Taruntius twins. Yes, between Taruntius P and K. And that rascal is right in-plane with us. I'm looking down now at 257. He's right down below us.

132:16:19 Engle: OK, Tom...

132:16:20 Stafford: Which means he's down low and he's going to be coming up.

132:16:27 Engle: Roger. OK. You don't have any idea, range-wise, about how far out he is, do you Tom?

132:16:35 Stafford: No, but I can see him occasionally in the sunlight down below. He couldn't be over 10 miles. Well, it's hard to say.

132:16:44 Engle: Yes. Roger.

132:16:45 Stafford: Seeing what I saw, Joe, yesterday - but we sure don't like to - around here playing footsie with that rascal.

132:16:52 Engle: Roger that.

132:16:54 Slayton: You guys treated him so bad on staging, he's out to get you.

132:16:59 Stafford: There he comes again.

132:17:06 Engle: OK. Are those the Taruntius craters you're showing us?

132:18:16 Engle: 10, this is Houston. That rille you're showing us now really is coming in clear.

132:18:43 Engle: 10, this is Houston. That sure is some mighty interesting territory you're showing us there. Those rilles and - look like slope features there are pretty darn interesting.

132:18:59 Engle: Apollo 10, Houston.

132:19:10 Stafford: Go ahead.

132:19:11 Engle: Roger, Tom. If you can kind of keep one eyeball peeled out for Snoopy, there, and give us another hack when you pick him up again, with relation to either pitch angle or some ground features, we might be able to get a rough estimate on what his orbit is.

132:19:30 Stafford: Well, that isn't the idea - Yes. OK. But the academic question, he was out in front of us and now he's moved down. It looks like our orbits are crossing. And I know...

132:19:40 Young: OK. There's Censorinus there, folks.

132:19:53 Young: And, boy, you can't - You can't see it from here, but is that rascal bright!

132:19:58 Engle: It sure looks bright from down here, John. It's standing out like a diamond.

132:21:12 Engle: And, 10, this is Houston. Is that area outside the bright ray, there - bright ray area, is that kind of brownish gray? That's the way it's showing up on our color, anyway.

132:21:41 Young: There's a [garble].

132:21:49 Young: OK. This is Rattlesnake and Diamondback Rilles, right here.

132:21:54 Engle: Roger.

132:22:32 PAO: The Serpentine rille is about a mile wide.

AS10-31-4601 Moltke

AS10-31-4601 showing Moltke

(Click on the above photograph for a larger version.)

132:22:39 Cernan: We're coming right - coming right into Site 2. The small craters that make a light ringing of Site 2 - You can see some of the ridges probably very plainly, and if we get there, John can probably show you Moltke, which will be on the right-hand side of your screen.

132:22:54 Engle: OK.

132:23:02 Cernan: And just to the right of Moltke is what we're calling U.S.1, which is a tremendously wide gulf.

132:23:44 Engle: OK. 10, this is Houston. We got you on the map there. Looks like you're panning right over the gashes right now, and just about to come into Moltke. Is that affirmative?

132:23:50 Cernan: That's affirmative.

132:24:07 Cernan: OK. Here's U.S.1, and we're just right over the landing site, ourselves, looking back.

132:24:14 Engle: Roger. U.S.1 standing out real good.

132:24:20 Engle: And we pick up a chuck hole right in the middle of U.S.1, there.

132:24:27 Cernan: Yes.

132:24:32 Cernan: You cam probably see where U.S.1 up here, it sort of looks like a straight slip fault. It's displaced the full width of the gulf, itself.

132:24:45 Engle: Roger.

132:25:01 Cernan: And, we're coming up on Sabine and Ritter, at this time.

132:25:06 Engle: OK.

132:25:23 Cernan: You're looking at Sabine and Ritter, and very shortly we’ll be crossing Schmidt. We just went over Landing Site 2.

132:25:44 Engle: OK. We're getting real good resolution again on this TV tonight. We're picking up all these things real good. And that's Schmidt crater. Is that affirmative?

132:25:54 Cernan: If I'm not mistaken. That's affirmative. You're looking right down into Schmidt.

AS10-31-4629 Schmidt

AS10-31-4629 showing Schmidt.

AS10-31-4630 Arago

AS10-31-4630 showing Arago

(Click on the above photographs for a larger version.)

132:26:02 Cernan: OK. Do you see any of the boulders around the edges that we can see from here?

132:26:08 Engle: Can't honestly say that we see anything like boulders there, Gene-o. It's sure a good picture, though.

132:26:19 Cernan: OK, Joe.

132:26:30 Engle: 10, Houston. We couldn't see any boulders, but we could sure make out the slumps on the inside of that crater, there.

132:26:42 Cernan: Some of these rascals look pretty deep to us.

132:26:46 Engle: Roger that.

132:27:12 Engle: 10, that shadow pattern on the bottom of that crater is real interesting. That looks like Theon. Does that copy with what you're showing us?

132:27:25 Cernan: Say again, Joe.

132:27:27 Engle: Roger. That crater you were just showing us, the shadow pattern on the bottom was a real interesting pattern, there. That looked like Theon crater.

132:27:37 Cernan: That's affirmative. You're right. We're almost past Landing Site 2 now, on the stretches up on into...

132:27:54 Engle: Roger.

Below is a sequence looking North towards Rima Ariadaeus.









(Click on the above photographs for a larger version.)

132:28:06 Cernan: OK. Here's an interesting - more than a ridge, it's a cliff-like ridge, jagged feature; it looks like it's smooth up to one end and then cliffs on the other side. It looks like it might also be very high in contrast. Much lower than some of the other surrounding craters, though.

132:28:25 Engle: Roger. I think we see what you're - what you're talking about.

132:28:27 Cernan: It almost looks - OK. It almost looks like it's a flow that's come down the valley and stopped right - right at that point, and then it's been dusted over. But it appears to be the front edge of some type of flow. The first time we really had a chance to look at that.

132:28:41 Engle: Yes. That looks real good from down here, Gene. We can pick that up. That's a good call.

132:29:05 Engle: Boy, that one really looks rough. I think we got that as Godin crater. Is that affirmative?

132:29:13 Cernan: That’s affirmative and the walls are very light, whitish-gray and the bottom is a dirty, dirty, tan. And it's got a central peak that - It's got very big boulders in the bottom. We can see from here. And it's got on the - On the far side, on the upper side of your screen, the side is slumped down in stages, it appears like, and it's not slumped down smoothly like you see on the bottom side. It's mostly in shadow, but you might be able to make it out.

AS10-31-4647 Godin

AS10-31-4647 showing Godin

(Click on the above photograph for a larger version.)

132:29:43 Engle: That's just great and that's a good call. That's a great description, too. We couldn't make the boulders out, but that slumping is coming through, just as you're describing.

132:29:58 Cernan: We're getting into the area of long shadows as we approach the terminator at this point.

131:30:06 Engle: Roger.

132:30:20 Stafford: OK. Pitching down at a half degree per second.

132:30:43 Engle: Apollo 10, this is Houston. I know you all are keeping an eye out for Snoopy. You haven't happened to seen him again, have you?

132:30:53 Stafford: Negative. It's going to be awful hard to. We're going into sunset here.

132:30:56 Engle: Roger.

132:30:57 Cernan: You know, about 4 minutes ago, I thought I saw him go - I thought about 4 minutes ago, I thought I saw a glimpse of him go vertically below us. However, it was just a quick glimpse. It was something glistening; it was hard to tell whether it was a close-by particle, or something way down, so I - I only saw it once.

132:31:14 Engle: Roger.

132:31:18 Cernan: We're moving to the left-hand window now because of the Sun off the hatch window.

132:31:23 Engle: OK. Gene, about 15 or 20 seconds ago, you were showing us a bunch of little - what looked like domes, there. Did they look like little domed hills to you?

132:31:38 Young: There's some little domes out there. There's plenty of little domes out there, now. Which ones you're talking about, I sure don't know.

132:31:47 Engle: OK.

132:31:53 Cernan: Tom's going to give you a look at a lot of rilles in the area he's looking at outside the left-hand window.

The sequence below shows Rima Hyginus.







(Click on the above photographs for a larger version.)

132:32:00 Engle: OK. Our signal is breaking up a little bit right now, but keep shooting. We'll try and get her squared away.

132:32:07 Cernan: OK.

132:32:37 Cernan: Joe, because the Sun's shafting on the forward window, Tom's got you out the left-hand window, looking to the north.

132:32:44 Engle: OK. We're still not getting a good picture. You'll...

Air-to-ground audio

132:32:46 Cernan: And as we see an area - We're seeing down in front of us a number of rilles that look very much like we saw back on Landing Site number 2 area. We're just beginning to see some of these areas because they're coming into sunlight now. The area right here, appears to be very familiar in terms of number of ridges and Highway 1 [U.S.1] type of rille, and I see again another area where a very wide rille, probably three-quarters of the widest Highway 1, where there's another, what could be or what would appear to be a strike-slip fault-type of movement between one side and the other.

132:33:28 Engle: OK. We've lost our picture, we think because of our High Gain Antenna, Gene-o. If it's possible, if you could - If you could rotate back around to your original attitude.

132:34:57 PAO: We've still not been able to lock onto the spacecraft High Gain Antenna. At this time, Apollo 10 should be just about over Landing Site 3 at an altitude of about 62 nautical miles [115 km].

132:34:07 Cernan: OK, Houston.

132:35:48 Engle: Apollo 10, Houston.

132:35:53 Cernan: Go ahead, Joe.

132:35:57 Stafford: Go ahead, Joe.

132:36:00 Engle: Roger, 10. We're just barely reading you. We’re not getting any TV picture now. Have you secured the camera?

132:36:18 Stafford: And one thing, we'll try to keep it on just a few minutes to see if we can pick up Earthshine, here.

132:36:23 Engle: OK. Very good.

132:36:24 Stafford: And what do your FIDO's say about Snoopy? Over.

132:36:27 Engle: I'm sorry, Tom; I cut you out. Say again.

132:36:31 Stafford: What do your FIDO's say about Snoopy? It appears in our analysis that basically we've seen him going small end forward. And now we were turned around and, you know, BEF, and he's always been out in front of us going above us, but this time he was right down below us. So it looks like we are catching Snoopy. Is that their analysis? Over.

132:36:54 Engle: Well, Tom, I think maybe we misunderstood your first call. When you first called him out on this pass, did you say he was down behind you and you were at about a 215 pitch angle?

132:37:08 Stafford: Well, he was - he was - We were looking right at him at 215 pitch. So evidently he's out in front of us. Well, maybe he is behind us. You see I didn't have the Orb Rate going. The computer wouldn't cough me out a solution [Verb 83] and so I was looking inertial, and I finally got him; and, as we were pitching around at 330, I think he was out in front of us. But he wasn't out in front of us near as much as he has been and he was down below us, definitely, and always before we've seen him out in front, but way up above. But there's no doubt he's getting lots closer. Over.

132:37:47 Engle: Roger. OK. And when he passed right directly below you, that was right over Taruntius. Is that correct?

132:37:57 Stafford: Yes. Around Taruntius; when we were there, he was down below us.

132:38:03 Engle: OK. We got that call OK. And we're trying to figure out what he - what Snoop's doing right now.

132:38:13 Stafford: Yes, I know it's highly improbable, a collision, but it'd ruin your whole day, if it ever happened.

132:38:19 Engle: Roger that.

132:38:44 Stafford: OK. I've got Snoop down there and – and reflected - I'm aiming right at him. He's down below us. I'm pitched at 336, and Snoop is in about the plus-X going across the crater. See him down there?

132:39:01 Stafford: He looks right plain. He's in reflected sunlight. He's in reflected sunlight; the rascal isn't too far out there. I'm now pitched at 340 degrees, and my X-axis is right at him so Snoop is out in front of us and below us. Over.

132:39:17 Engle: Roger. We copy, Tom. And he's probably coming up. Is that affirmative?

132:39:23 Stafford: That's affirmative. I would say he'd be coming up and heading up towards his apogee.

132:39:28 Engle: Roger that.

132:39:29 Stafford: Or should I say apolune?

132:39:32 Engle: Roger.

132:39:33 Stafford: He's moved out in front of us.

132:39:43 Cernan: He's just playing into his own sunset right now. We've just lost him.

132:39:47 Stafford: We may be able to pick him up in Earthshine.

132:39:51 Engle: OK. We'll crank those angles in and that, alongside of your sighting of him right directly under you over Taruntius, that should - We should be able to come up with some sort of a guesstimate on how close he's going to be. The FIDO troops think that when you saw him directly under you, that's probably the closest point that he'll be to you in his orbit. We're going to keep working that, though, Tom.

132:40:14 Stafford: OK. Of course, you know, in reflected - right, Joe. In reflected sunlight it's awful hard. However, earlier, just - We could see the sparkles off of his legs, you know - and some different colors there as the sun would rotate off the panels, but that was with the 28 power monocular. Over.

132:40:31 Engle: Roger. Understand. That's still plenty close.

[The orbit the LM was in at staging was 190 x 11.8 nm (305 x 19 km), and the descent stage would still be in an orbit approximating these values. Therefore the orbital period of the LM descent stage is longer than that of the CSM and on the nearside the descent stage would be descending from its high point down to the low point of it's orbit, well below that of the CSM which is current in an orbit of 67.6 x 54.1 nm (125.2 x 100.2 km). Due to the differing orbital periods, the CSM has now completed an extra orbit compared to the descent stage and in effect is now lapping it.]

CSM & LM descent stage relative orbits

Diagram showing the relative orbits of the CSM and the LM descent stage.

132:40:36 Stafford: Yes, I'd say so. OK. We have Earthshine real good here, and Gene will try to give it to you out the window. We got the...

132:40:56 Engle: OK. Old Snoop's just a devoted old hound dog, Tom. He'll probably try and follow you back home.

132:41:04 Stafford: Just as long as that rascal doesn't sniff too close.

Air-to-ground audio

132:41:53 Cernan: Joe, Earthshine is very bright to us, but it doesn’t appear like it's going to be very bright to the camera. I don't think we're going to get anything. I thought maybe we'd even get the Earthshine horizon here, but I don't think that...

132:42:06 Engle: OK. I'm afraid we're not getting any picture at all down here, Gene.

132:42:17 Stafford: OK, Joe. We'll go ahead and terminate. I thought the light level was pretty low where the eye could adapt to it. It's pretty dark down there, I must admit.

132:42:27 Engle: OK. Mighty fine. I've got a couple of landmark tracking updates and a map update for you when you're ready to copy.

132:42:38 Stafford: Stand by. We're getting ready to get the camera secured and some other stuff.

132:42:45 Engle: Roger that.

132:43:19 Stafford: OK. Houston, Apollo 10. Go ahead.

132:43:27 Engle: OK, Tom. I'll give you the landmark tracking update PADs first. This is for Rev-30. Your T-1 is 134:15:56; T-2 is 134:17:30. For roll, all balls; pitch, 282; and yaw, all balls; north 29 29 41. And that was for site B-1. For 150: T-1 is 134:27:40, 134:29:12. Roll is all balls; pitch, 246; yaw, all balls; north 02 02 40. And I'll stand by for readback on those two.

132:43:45 Stafford: OK. Give me the first one on B-1. I missed that, the first T-1.

132:43:49 Engle: Roger. T-1 is 134:15:56.

132:45:10 Stafford: OK. with the readback: T-1 for B-1; 134:15:56, 134:17:30; 000, 282, 000; north 29 29 41. 150: 134:27:40, 134:29:12; 000, 246, 000; north 02 02 40.

[Landmark tracking PAD breakdown for revolution 30:

Target B-1
T-1: 134:15:56 (Initial point when the target is on the local horizon.)
T-2: 134:17:30 (When the spacecraft is at an elevation angle of 35° above the target.)
Roll: 000°, Pitch: 282°, Yaw: 000°
Target 29 nautical miles North of the groundtrack.
SA-Shaft angle: 29°, TA-Trunnion angle: 41°.

Target 150
T-1: 134:27:40 (Initial point when the target is on the local horizon.)
T-2: 134:29:12 (When the spacecraft is at an elevation angle of 35° above the target.)
Roll: 000°, Pitch: 246°, Yaw: 000°
Target 2 nautical miles North of the groundtrack.
SA-Shaft angle: 2°, TA-Trunnion angle: 40°.]

132:45:46 Engle: Roger. That's good copy on a readback, and let me know when you're ready for your map update.

132:45:57 Stafford: Go ahead, Joe.

132:45:59 Engle: OK. This is for Rev-30: LOS will be 133:10:56, 133:21:44, 133:57:05.

132:46:23 Stafford: Roger. Readback: 133:10:56, 133:21:24, and 133:57:05.

132:46:31 Engle: OK. On your second row there, Tom, that's 133:21:44.

132:46:47 Stafford: Roger. That's 133:21:44.

[Rev-30 map update details are:
LOS: 133:10:56
crossing 150°W: 133:21:44
AOS: 133:57:05.]

132:46:53 Engle: Roger. That's correct, Tom.

132:47:10 Stafford: OK. John's going to an IMU realign just for academic interests. I'd like to talk a little more about Snoopy. Obviously, he was out in front of us, and he'll be going out in front of us and coming up higher. As such, I'm trying to make a relative motion plot in my own mind here, and it looks like at TEI, if he continues to do that and we burn and zip out there, well we could be fairly close. Over.

132:47:40 Engle: OK. Tom. What FIDO has come up with - if you initially pick him up behind or if he was behind you and then he passed directly below you, and if coming up in front of you now, what he should do is continue to climb on up above you and, therefore, fall back behind. And he'll continue to fall behind, and at TEI, you should be between 5 or 600 miles [930 to 1,110 km] out in front of him. What has happened, evidently, is you've lapped him once and this probably will be the only time you'll get a chance to see him until you leave the lunar orbit.

132:48:16 Stafford: OK. That's what my initial estimate was and what I called into Charlie earlier. It looked like that we were, you know, naturally he went away, out - oh, above us and behind us, and it looked like we'd already caught up with him. And I didn't know what the rate of catch-up was. But - the whole thing when we saw him down below and like that, I see - so we've already lapped him and he's going to continue to go. That's good. Over.

132:48:44 Engle: Roger. Understand, Tom.

132:48:48 Stafford: I could tell we're right in the place where the orbits would cross and I was trying to plot a relative motion, picture in my mind and fly at the same time, and do a few other things, and it wasn't too easy. But there’s no doubt about it, we were so close to the rascal you could see different colors in the sunlight between the black and silver panels on the sides of the descent stage there. Over.

132:49:12 Engle: Roger. That's getting pretty close.

132:49:19 Stafford: Yes, I admit that the possibility of a rendezvous is real low, but still just like to keep my hand on it. Over.

132:49:27 Engle: Roger that, Tom.

132:49:32 Unidentified MCC-H: Roger.

132:49:38 Engle: 10, this is Houston. Tom, other than this rev, can you recall what other revs you've seen Snoopy on?

132:49:49 Stafford: We've seen Snoopy every rev on the landmark tracking. And - You know the landmark tracking we did for those four revs? And every time he was out in front of us and would disappear over our head. Over. And when - that's - We were going just about local - We were pitching down from local horizontal about 20 degrees, you know, as John was doing the landmark tracking, maintaining orb rate, and Snoop would come up over the horizon and then disappear out over our center hatch window. And each time it looked like we were getting closer, which meant, you know, that we were catching him. Over.

132:50:25 Engle: Roger. Understand.

132:50:49 Stafford: Roger, Houston. Like I know we were lapping him, but like I said, he was out in front of us now and the whole thing what I was concerned about was the next two relative perigees that Snoop would make the way he'd be coming down and what our pitch would be in that period of time. Over.

132:51:10 Engle: OK, Tom. We understand that, what you told us. We're trying to piece together what seems to be the most logical route that Snoopy’s taking there.

131:51:21 Stafford: OK.

132:51:22 Cernan: Joe, since we were late changing our last canister, do you want us to back off this one or do you want us to change it on time?

132:51:34 Engle: OK, 10. We'd like for you to go back on the normal schedule.

132:51:41 Cernan: OK.

[Comm break.]

Air-to-ground audio

132:55:11 Stafford: OK, Joe. I'm going to rol1 over 180 degrees here.

132:55:16 Engle: OK.

132:56:46 PAO: Apollo 10 is now in an altitude of 68.1 nautical miles [126.1 km] approaching apogee 68.2 [126.3 km], we should say apolune. The crew has just completed realigning their guidance platform. Shortly after we lose touch with the spacecraft...

132:57:17 Young: Houston, this is Apollo 10. Over.

132:57:22 Engle: Roger, 10. Go ahead.

132:57:26 Young: Roger. We're showing a 68.5 by a 53.6 [nautical miles, (126.9 x 99.3 km)]. Where is the perilune now? At what point...

132:57:33 Engle: Stand by. I'll get it.

132:57:34 Young: ...over the surface, is it?

132:57:37 Engle: I cut you out there at the last, John. Say your last again, please.

132:57:43 Young: At what point over the lunar surface is perilune?

132:57:46 Engle: OK. I'll get that for you. Just a minute.

132:58:37 Engle: Apollo 10, Houston.

1322:58:42 Young: Go ahead. Over.

132:58:43 Engle: Roger. John, we've got your perilune there at 58 minutes north and longitude is 86 degrees, 58 minutes east.

132:58:56 Young: Roger.

132:59:28 Young: That means the people that were watching the TV were watching at the closest point of approach?

132:59:34 Engle: That's affirmative, John.

132:59:44 Young: Hey, Joe, is it 1 o'clock in the morning or 1 o'clock in the afternoon.

132:59:49 Engle: It's just about 1 o'clock in the morning.

132:59:54 Young: What morning?

Flight Plan

133:00:01 Engle: It's Saturday morning. The 24th, John. Can't you guys what - where it is daytime, there?

133:00:14 Stafford: Oh, yes. We can see how the Sun progresses across the Earth up there every time we get an Earthrise. Over.

133:00:19 Engle: Roger.

133:00:21 Young: You ever see Earthshine - you can see the – when you get night adapted - you can see the lunar surface through the telescope, almost well enough so that I believe you might be able to do landmark tracking, on some large feature.

133:00:39 Engle: Very good.

133:00:41 Young: You - You can't see anything through the sextant, but the large features come through loud and clear in Earthshine.

[As a 28-power instrument, the sextant would be expected to have an intrinsically dimmer image than a one-power instrument, like the telescope.]

133:00:55 Cernan: Joe, I'm going to lose you. I'm going to put you on omni.

133:00:58 Engle: OK. Thank you, Gene.

133:01:00 Young: I don't know why we didn't think to look for that before.

133:01:12 Engle: John, this is Houston. Do you think that you could pick up the same type of features in Earthshine but about within 10 degrees of the terminator?

133:02:49 Cernan: Houston, do you read us at all?

133:02:52 Engle: OK. Apollo 10, this is Houston. We're reading you now, John.

133:03:00 Cernan: You keep calling me by the wrong name.

133:03:05 Engle: You keep sounding like the wrong guy.

133:03:12 Cernan: I keep getting mixed up myself.

133:03:31 Cernan (onboard): T.P., we're hanging right about 27 miles (50 km), and we've still got a battery charge to go.

133:03:37 Stafford (onboard): Huh?

133:03:39 Engle: Hey, Apollo 10, this is Houston. On your comment on being able to pick up these features through the - through the telescope in Earthshine, do you think you could pick up these features within about 10 degrees of the terminator?

133:03:52 Stafford (onboard): Oh, shit.

133:03:53 Engle: This is still in the Earthshine?

133:03:56 Stafford (onboard): Man, that would be rough.

133:04:01 Young: The Earthshine terminator or the nighttime terminator?

133:03:59 Stafford (onboard): We go from Earthshine to nighttime.

133:04:05 Young (onboard): No; I do not, because...

133:04:06 Engle: The nighttime terminator.

133:04:08 Young: No. I do not, because - No. You mean 10 degrees?

133:04:14 Engle: Roger.

133:04:15 Young: Which Earthshine are you talking about? The regular front terminator? It would be impossible, because you're not that adapted. You can't see anything when you go into the dark through the telescope.

133:04:29 Engle: Roger. Thank you.

133:04:16 Cernan (onboard): They're talking about the regular Sun terminator, John.

133:04:19 Young (onboard): The regular Sun terminator would be impossible, because you're not night-adapted. You can't - you can't see anything when you go into the dark through the telescope...

133:04:30 Young: ...until you get night adapted and then you can – then you can see - then you can see all the terrain features.

133:04:35 Stafford: Now, we may...

133:04:37 Engle: Yes. OK. We understand. Thank you.

133:04:50 Young (onboard): Stupid, freaking question.

133:05:00 Stafford: OK, Houston. Apollo 10. All the way through the landmark tracking we shot photos of opportunity, and we just about ran out of film here we shot so much of it. So on this one we're just going to maintain orb rate with our heads up here and - instead of heads down - but we can get pretty good coverage really out the side windows, and we shot the whole strips out the other way. So we're – on the rev we're just going to maintain orb rate with heads up. And I - and I don't think there's really any photos of opportunity that we haven't already got, but we'll still be shooting some.

133:05:34 Young (onboard): What they would like to have when you can is get photos - what they would like to have when you can get them is photos of the horizon, photos of the...

133:05:42 Engle: OK, Tom. We understand.

133:05:44 Young (onboard): of the sort of a strip on the side. A strip photo of the...

133:05:49 Stafford (onboard): Sideways?

133:05:52 Young (onboard): Yes, but do you know what I'm talking about?

133:05:53 Stafford (onboard): You mean out this way?

133:05:54 Young (onboard): Yes, they'd like to have photo - oblique out showing just the - just the horizon a little bit. In other words, because that gives them an idea of what - of what - the horizon gives them a real good hack on the elevation.

133:06:06 Engle: Apollo 10, Houston.

133:06:12 Cernan: Go ahead. Over.

133:06:13 Engle: Roger, 10. FIDO is predicting that on the backside at sunrise at 133:26, that Snoopy, should be directly overhead. So if you pitch up you right - might be able to pick him up and - right at sunrise.

133:06:30 Stafford: Roger. At sunrise, 133:26. Thank you.

133:06:30 Young (onboard): Freak it. Screw him.

133:06:33 Cernan (onboard): I think he's a little early.

133:06:35 Young (onboard): If he's directly overhead - if he's in the phasing orbit, he'd be at 300 miles [555 km], wouldn't he?

133:06:45 Stafford (onboard): He'd be 200 miles [370 km] plus what he's torqued at.

Air-to-ground audio

133:07:13 Stafford (onboard): The whole thing - I wasn't - It took so damn long to get that Verb 83 up, I wasn't sure about...

133:07:19 Young (onboard): Yes, that damn thing is really bad...

133:07:20 Cernan (onboard): Boy, it takes long in the LM, too, remember that, Tom; how long it took to get that thing up?

133:07:25 Stafford (onboard): I think if I'd had a quick Verb 83, I could have given him marks on what we were tracking on.

133:07:27 Young (onboard): Let me see that a minute.

133:07:40 Stafford (onboard): Yes. If we don't see the son of a gun out in front anymore, like maybe we done - he's done passed behind us.

133:07:50 Young (onboard): Those guys don't have the foggiest blessed notion where he's at; I bet you a hundred bucks.

133:07:56 Stafford (onboard): I think Shaffer - Oh, Phil Shaffer will.

[Phil Shaffer is the FIDO on the black shift of flight controllers, under flight directors Glynn Lunney or Gerry Griffin.]

133:07:59 Cernan (onboard): You've got one more Hill to do, John. And one more P52 to do.

133:08:06 Young (onboard): And that's the one that counts. Right? When do we do that? You mean before we get out of the dark here?

133:08:17 Stafford (onboard): No, after landmark tracking.

133:08:19 Young (onboard): After landmark tracking.

133:08:20 Cernan (onboard): You want to change the canisters, John?

133:08:23 Young (onboard): Yes.

133:08:24 Cernan (onboard): Canister A; 13 to A and 11 to A-3.

133:08:37 Young (onboard): 13 to A, and 11 to A-3. OK, excuse me, Tom.

133:08:45 Engle: Apollo 10, this is Houston. We show LOS here in about 2 minutes, and we should pick you up again at 133:57, which is about 48 minutes from now. We'll keep in contact with you until you go around the corner.

133:09:03 Stafford: OK, Joe. Real good. Thank you.

133:09:27 Young (onboard): Nice place to live, but I wouldn't want to land there (laughter). We got him. don't we? Let's tell Neil that (laughter). 13 to - to where? 13 to where, babe?

133:09:47 Cernan (onboard): 13 to A.

133:09:49 Young (onboard): Oh, shit, John; you dumb shit. Excuse my tongue.

133:09:50 PAO: And we've had Loss Of Signal. Apollo 10 looked good as it went around the corner. We'll next acquire the spacecraft in about 46 minutes, early in the 30th revolution. During this revolution, we had some interesting comments from the crew relative to sightings of Snoopy's descent stage, which was left in an orbit of about 10 nautical miles by 190 nautical miles [352 km]. Of course the LM ascent stage is now in solar orbit. The crew reported that they had seen Snoopy on each landmark track rev, which would have been rev 24, 25, 26, and 27; the spacecraft, rather the LM descent stage, appearing out in front and then as Stafford described it disappearing overhead. And each time he said Snoopy would appear to come closer indicating that the CSM was catching and in effect lapping the Lunar Module. The ground here in Mission Control concurred with that analysis, the Flight Dynamics Officer estimated that at the time of Trans-Earth Injection, the Command Module would be about 500 or 600 miles [930 or 1,110 km) out in front of the LM descent stage. We advised the crew that if they looked directly overhead at 133 hours, 26 minutes, which would be sunrise on the back side of the Moon, they should be able to see Snoopy directly overhead. As the spacecraft went around the corner of the Moon, we were showing an orbit with an apogee of 68.5 nautical miles [126.9 km], and a perigee of 53.3 [98.7 km]. The orbit continuing to show a decrease in perigee and increase in apogee. The spacecraft orbital weight at this time, is 36,685 pounds [16,640 kg], and the orbital period is 1 hour, 58 minutes, 50 seconds. At 133 hours, 14 minutes; this is Mission Control, Houston.

133:09:56 Cernan (onboard): And 11 to A-3.

133:10:15 Stafford (onboard): OK.

133:10:15 Engle: OK, 10. This is Houston. We'll probably lose you here in about half a minute, so we'll see you on the next round; and keep an eye for ol' Snoop.

133:10:25 Stafford: OK. Will do, Joe. Thank you.

133:10:38 Stafford (onboard): What's been the burn times on those TEIs? 2 minutes and...

133:10:43 Cernan (onboard): Roger; 2 minutes and - almost 3 minutes.

133:10:48 Young (onboard): God, you can tell when you lose them, can't you?

133:10:50 Stafford (onboard): Yes.

133:10:57 Cernan (onboard): We're not going to do this black and white test, are we?

133:11:00 Stafford (onboard): Do what?

133:11:02 Cernan (onboard): Black and white TV test?

133:11:03 Stafford (onboard): No.

133:11:05 Young (onboard): They want us to.

133:11:06 Cernan (onboard): Man, that's like wringing out the dirty - you know, the dirty bras after you've [garble] in the program.

133:11:12 Stafford (onboard): Yes. At least I feel better about Snoopy. We can't say it's impossible we'd ever hit him, but that rascal didn't look - it looked out of plane earlier when we were right on keel...

133:11:20 Young (onboard): [Garble] sure it didn't look out of plane when we...

133:11:22 SC (onboard): (Laughter)

133:11:24 Stafford (onboard): [Garble] right down the bellyband.

133:11:26 Young (onboard): That son of a bitch has got the right idea.

133:11:31 Cernan (onboard): This is beautiful. We eat breakfast and then we go to sleep.

133:11:38 Stafford (onboard): That little nap sure helped out.

133:11:39 Young (onboard): Boy, I tell you I feel like a new man. Feel good.

133:11:46 Stafford (onboard): OK, after - Let's see - after landmark tracking, we've got just a whole REV there to do nothing but just get squared away, right?

133:11:54 Cernan (onboard): No. We don't. That's what I'm looking at. Son of a bitch. We're doing targets of opportunity...

133:12:00 Stafford (onboard): Freak it.

133:12:01 Cernan (onboard): ...strip photos right up until - shit, that's what we're doing. Discontinue strip photography at 136:15, and we burn at about 137:15. And between there, John's got to do a P52, we've got to roll to TEI attitude, P52, P30, P40; we lose them in 30 minutes after that - no - 25 minutes after that.

133:12:26 Young (onboard): That's no sweat; we'll make it.

133:12:28 Cernan (onboard): Yes, but God dang.

133:12:29 Stafford (onboard): What have we got to do? How much time have we got left?

133:12:33 Young (onboard): Shoot up the rest of the black and white.

133:12:35 Cernan (onboard): Yes. We'll shoot up the black...

133:12:36 Stafford (onboard): Yes. Shoot the stuff out to the side.

133:12:39 Young (onboard): Shoot, they're interested in the elevation. They won't bother you.

133:12:45 Stafford (onboard): What do you...

133:12:46 Young (onboard): You can get it all on this REV, for that matter. But just don't get too much of the horizon. They just want...

133:12:52 Stafford (onboard): Just the horizon right near the top.

133:12:54 Young (onboard): Yes, well. Yes. The horizon near the top - and then that gives them an idea - that gives them the best estimate of elevation of the terrain.

133:13:06 Cernan (onboard): I see [garble] the horizon [garble].

133:13:24 Stafford (onboard): If you look back like that at sunrise, you should be able to see Snoop, if he's up there. You see anything out there now?

133:13:37 Young (onboard): A few stars.

133:13:43 Stafford (onboard): Did we put any tape over that fuel cell 1 light?

133:13:46 Young (onboard): No!

133:13:47 Stafford (onboard): Why?

133:13:48 Young (onboard): Because it burns. Son of a bitch is going to get hot. That thing...

133:13:57 Stafford (onboard): There's fuel cell 2.

[The Fuel Cell 2 caution and warning light has come on, on panel 2.

FC2 C&W light on P2

Fuel cell 2 caution and warning light on panel 2.

(Click on the above diagram for a larger version.)

The condenser exhaust temperature is cycling between 149° and 168°F [65° and 76°C] at a rate of 2 cycles/minute for 30 to 40 minutes while the spacecraft was behind the Moon over the unlit portion and that the caution and warning alarm for low temperature had been triggered about every tenth cycle. The maximum amplitude of the oscillations in temperature was about 20°F [11°C].

FC2 condenser exhaust temp gauge P3

Fuel cell condenser exhaust temperature gauge on panel 3.

(Click on the above diagram for a larger version.)

Following the pump failure on fuel cell 1, it dictated two fuel cell operations. The oscillations in the fuel cell condenser exhaust outlet temperature occurred when low radiator temperatures, less than 80°F (27°C) and high current loads prevailed. Furthermore, the oscillations damped out for radiator temperatures greater than 115°F (46°C), once they were back in sunlight. The same issue was observed on at least one fuel cell on each of the previous manned Apollo missions.]

FC2 condernser exhaust temperature oscillations graph

Fuel cell 2 condenser exhaust temperature oscillations.

133:13:59 Cernan (onboard): What did you do? May have been while I was sleeping. I must be confused.

133:14:10 Young (onboard): What the hell's the matter with fuel cell 2?

133:14:12 Cernan (onboard): I think it's this heater's cycling.

133:14:15 Stafford (onboard): Let's tell them about it.

133:14:16 Cernan (onboard): Something's wrong with the heater [garble].

133:14:23 Young (onboard): You bet.

133:14:29 Cernan (onboard): See?

133:14:34 Young (onboard): Why should the goddamn light come on? Oh, that's right, because...

133:14:39 Cernan (onboard): [Garble] just below the [garble]...

133:14:40 Young (onboard): ...because - because that caution and warning [garble] was set right on its goddamn, edge.

133:14:43 Cernan (onboard): ...cycles. [Garble] can't do that.

133:14:53 Young (onboard): Tell them about it.

133:14:54 Cernan (onboard): We can't. I ain't talking to them.

133:14:56 Young (onboard): Oh, I mean; well, why didn't you tell them about it before?

133:14:58 Cernan (onboard): Because I didn't see that before.

133:14:59 Young (onboard): Oh.

Rev 30 attitude diagram

Planned spacecraft attitudes during rev 30.

(Click on the above diagram for a larger version.)

[133:15:-- Begin lunar Rev-30]

133:15:00 Cernan (onboard): [Garble] it was a high [garble] I didn't see that before.

133:15:05 Stafford (onboard): So what have we got on it? The high flow?

133:15:08 Cernan (onboard): No. We got a...

133:15:09 Young (onboard): No. The flow's normal.

133:15:10 Cernan (onboard): It's just the [garble] the exhaust temperature is [garble].

133:15:18 Young (onboard): Weird thing.

133:15:24 Cernan (onboard): Well, now the computer really controls both these primary [garble] - It could be that goddam pump package [garble], too.

133:15:29 Stafford (onboard): No shit. Pump package going out on that one? Wouldn't that be the shits to get it - in the back and turn those gimbal motors on and get your main bus undervolts and all that?

[Stafford is pointing out that it would not be good if, when they are preparing for the TEI maneuver and they power up the SPS gimbal motors, they could get a Master Alarm due to main bus undervolts, as the malfunctioning fuel cells are unable to carry the extra electrical demand during the burn.]

[At this point, the crew is to some extent speculating about the nature of the second fuel cell problem. Stafford is questioning whether they have also lost the H2 pump package on fuel cell 2.]

133:15:46 Young (onboard): What would you do?

133:15:50 Stafford (onboard): Would the batteries carry those mo - those gimbals?

133:15:52 Cernan (onboard): We've - we've still got some pretty good fuel cells right now. We've still got fuel cell 1.

133:15:59 Stafford (onboard): Will the batteries and that carry them?

133:16:04 Young (onboard): Yes. Well, I mean, we ain't got - Fuel cells will work; we just got to learn how to baby them, that's all.

133:16:19 Cernan (onboard): [Garble] up and down.

133:16:30 Young (onboard): Did you drive the pressures up and down?

133:16:33 Cernan (onboard): Look at the - look at the - see if there's something on the fuel cell - fuel cell condenser exhaust - see if there's something on the - on the pumps down there- in your glycol temperature - something out there, that says something about fuel cell - there is something on your [garble] down there.

133:16:52 Young (onboard): Yes? Nothing about the pump. There's regulators OK, fuel cell radiator outlet temperature, fuel cell - fuel cell 2 radiator outlet temperature, let's take a look at that.

133:17:13 Cernan (onboard): Compare them. Compare them. Compare - compare them all.

133:17:18 Young (onboard): OK.

133:17:20 Stafford (onboard): I'm going to power down my GDC for a while. OK.

[Stafford is still focussed on reducing the electrical load on the remaining active fuel cells. Temporarily, by pulling the Logic Bus 3/4 MNA and Logic Bus 1/4 MNB circuit breakers on panel 8, he can remove the GDC from use, bringing it back on line during the preparations for the TEI maneuver.]

SCS Logic Bus cb P8

SCS Logic Bus circuit breakers on panel 8.

(Click on the above diagram for a larger version.)

133:17:24 Young (onboard): Alright.

133:17:30 Cernan (onboard): There it is again.

133:17:35 Young (onboard): Same thing?

133:17:42 Cernan (onboard): It's the cooling system on that god-dang fuel cell 2. Now. It's the same thing we had on these other ones.

133:17:50 Stafford (onboard): Hey, look, what we can do - Let's talk to them. Let's don't freak around with this situation.

133:17:57 Young (onboard): I don't know what the shit here.

133:17:58 Cernan (onboard): Hey, it seems like an hour; it's been 2 hours, you guys.

133:18 08 Stafford (onboard): If we can make a good platform alignment and get out of here in a hurry, we've got a good state vector. Even though we'd like to keep to the nominal mission. What do you see on it? You got the Mal[function] procedures out there?

133:18:21 Cernan (onboard): Yes, Tom. It's the same thing except the [garble] can't hold it. What bothers me is that - is that - It's not this regulator pump; the damn thing's still working.

133:18:45 Young (onboard): 3-B, -C, and -D.

[Young is referring to readouts from the System Test Meter in the Lower Equipment Bay. The readouts provide the following data:

3-B: EPS Radiator Outlet Temperature for fuel cell 1. Range between -50°F to + 300°F.

3-C: EPS Radiator Outlet Temperature for fuel cell 2. Range between -50°F to + 300°F.

3-D: EPS Radiator Outlet Temperature for fuel cell 3. Range between -50°F to + 300°F.]

133:18:56 Stafford (onboard): Has any spacecraft had fuel cell problems before?

133:19:00 Young (onboard): Yes.

133:19:01 Cernan (onboard): Which one?

133:19:03 Stafford (onboard): Which one? They've had condenser-exhaust problems.

133:19:05 Young (onboard): I heard that the D [Apollo 9] was open-circuited before they came in. There's no motion there, and the condenser and radiator outlet temperatures are constant.

133:19:21 Stafford (onboard): On all of them?

133:19:22 Young (onboard): Yes.

133:19:24 Cernan (onboard): What else you got to look at?

133:19:26 Young (onboard): Let's see. That was 3-B. -C, and -D. OK, let's look at - Well - 1-A, -B, and, -C. Fuel cell 1 and 2, Reg pressure. 1-A. -B, -C.

[The crew are now checking the following System Test Meter readouts:

1-A N2 regulator out pressure for Fuel Cell 1. 0 to 75 psia (pounds per square inch, absolute, or with respect to vacuum).

1-B N2 regulator out pressure for Fuel Cell 2. 0 to 75 psia.

1-C N2 regulator out pressure for Fuel Cell 3. 0 to 75 psia.]

133:19:42 Stafford (onboard): They all look good, huh?


AS10-31-4653 showing the far-side crater Spencer Jones.


AS10-31-4657 showing the far side crater Papaleski.

(Click on the above photographs for a larger version.)

133:19:43 Young (onboard): OK, B is a little higher. A's a little lower. The Reg pressure's OK. 1-C. -D, and 2-A, 1-D, -A and-B; 1-D, that's O2 regulator pressure. 2-A and -B. Well, the O2 Reg pressure on 2 is a little high. It's carrying a lot of load.

[Further readouts from the System Test Meter provide the following data:

1-D O2 regulator out pressure for Fuel Cell 1. 0 to 75 psia.

2-A O2 regulator out pressure for Fuel Cell 2. 0 to 75 psia.

2-B O2 regulator out pressure for Fuel Cell 3. 0 to 75 psia.]

133:20:31 Cernan (onboard): Is it out of spec?

133:20:34 Young (onboard): No. it's in the nominal range, 3.9 to 4.6. And then, 2-C, fuel cell 1 H2 pressure Reg, 2-D, 3.8 to 4.5; those are all ok. And 3-A, that crummy-looking - That's all - they're all the same. So everything's the same. Even with the bad one. Everything that we could read.

[System Test Meter readouts continue, providing the following data:

2-C H2 regulator out pressure for Fuel Cell 1. 0 to 75 psia.

2-D H2 regulator out pressure for Fuel Cell 2. 0 to 75 psia.

3-A H2 regulator out pressure for Fuel Cell 3. 0 to 75 psia.]

133:21:34 Cernan (onboard): Oh. shit. I just don't like the way it's cycling up and down. up and down.

133:21:40 Stafford (onboard): Well. when they - Once we make TEI, we can tie a bunch of stuff down here.

133:21:47 Young (onboard): Yes.

133:21:48 Stafford (onboard): Turn off the BMAGs.

133:21:50 Cernan (onboard): That's why - that's why I don't like to sit on our ass, you know? [Garble].

133:22:01 Stafford (onboard): We can fire TEI at the end of this rev. We'll talk...

133:22:05 Cernan (onboard): [Garble] a nice little item.

133:22:08 Young (onboard): Well, let them look at it. They'll want to look at the freaking thing. They're going to make up their mind about the time we do TEI.

133:22:22 Cernan (onboard): TEI is in 4 hours.

133:22:48 Young (onboard): I don't really think this will show up when we get the batteries on.

133:22:53 Cernan (onboard): John. don't you think we ought to take some of those things from out there and snap them on the - snap them on the floor?

133:22:59 Young (onboard): Yes. I'll do that, as a matter of fact.

133:23:03 Cernan (onboard): Here. I've got a mess of film that we could [garble].

133:23:07 Stafford (onboard): Oh.

133:23:08 Young (onboard): Have you got any that's all used up? We'll stick it back. huh?

133:23:12 Stafford (onboard): It's used up. Keep that color exterior film and haven't we - we got the two color backs? We're going to get some great pictures with them. You got some sequence camera film for the Moon going away because once we turn around, it's going to be pretty phenomenal, and we'll bring out the boob tube then and throw it on.

133:23:39 Young (onboard): OK.

133:23:57 Young (onboard): Here comes a thread floating up to get you. Hell, there's three pack - three things already in there.

133:24:09 Cernan (onboard): Stand by the [garble].

133:24 10 Young (onboard): Yes.

133:24:12 Cernan (onboard): What a [garble].

133:24:16 Stafford (onboard): There it - it's stalled again.

133:24:17 Young (onboard): Same thing?

133:24:18 Cernan (onboard): Yes. [Garble]. Let's just [garble] here.

133:24:24 Young (onboard): Yes. No, it goes behind here.

133:24:55 Young (onboard): OK. Watch your fingers. Where does this here go? In R-13?

133:24:57 Cernan (onboard): What?

133:24:58 Young (onboard): In R-13?

[Young is referring to storage compartment R13 which is on the right wall of the crew compartment at approximately the same level as the couch head rests.]

Storage compartment R-13

Storage compartment R-13.

(Click on the above diagram for a larger version.)

PAO audio

133:25:XX PAO: This is Apollo Control at 133 hours, 25 minutes. We're still about 32 minutes from reacquiring Apollo 10. The spacecraft will shortly be beginning its 30th revolution of the Moon. We have some additional information from our Flight Dynamics Officer on the relative positions of the Command and Service Module and Snoopy's descent stage. The analysis of the relative orbits of the two spacecraft shows that Snoopy has apparently been - or rather the Command and Service Module has apparently been lapping Snoopy, as we said, and we believe that the point of closest approach of the two spacecraft occurred during the current revolution when Tom Stafford and John Young were describing their sightings of the LM descent stage. Not necessarily at exactly that time, but sometime during that revolution, we believe, the point of closest approach of the two spacecraft occurred. From now on, the orbits - the relative orbits, will take Snoopy farther behind - Snoopy, of course, being in a higher orbit, thus taking longer to complete a revolution. The Command Module will continue to move out in front so that by the time Trans-Earth Injection occurs, Snoopy should be about 5 to 600 miles [930 to 1,110 km] behind at its point of closest approach. At 133 hours, 27 minutes into the flight of Apollo 10; this is Mission Control.

133:25:07 Cernan (onboard): No, that's a [garble].

133:25:11 Young (onboard): Yes.

133:25:12 Cernan (onboard): [Garble]. They're closed.

133:25:38 Stafford (onboard): Is that- OK, here comes sunrise. Now, watch it. I want to pitch up. See if you can see anything straight up.

133:26:09 Cernan (onboard): [Garble].

133:26:10 Young (onboard): Man, that [garble].

133:26:31 Young (onboard): You want to put these here down near the floor?

133:26:45 Stafford (onboard): What about snapping those things - like that? Just...

133:26:50 Young (onboard): Oh, yes.

133:26:55 Stafford (onboard): I don't know whether that will reach with that end.


AS10-31-4660 showing the far side crater Schuster.


AS10-31-4665 showing the far side craters Harden (foreground) and Fischer on the floor of Mendeleev.

(Click on the above photographs for a larger version.)

133:28:06 Stafford (onboard): What about this bear? You think you [garble] up and down?

133:28:07 Young (onboard): What?

133:28:10 Stafford (onboard): This one here.

133:28:13 Young (onboard): It probably will, unless we tie it up.

133:28:16 Stafford (onboard): Here, you can - can you double it back on the -

133:28:22 Young (onboard): If I had a strap, I'd strap it to this here thing, right here.

133:28:24 Stafford (onboard): You don't want anything coming down and whopping you during that burn.

[The application of thrust at TEI will impart an acceleration that is not dissimilar to Earth's gravitational acceleration. It will also impost a temporary sense of which way is down.]

133:28:28 Young (onboard): No. Here, let's get this - let me get - Well. I don't see any more straps.

133:28:42 Stafford (onboard): Here's somebody's ear.

133:28:46 Young (onboard): I thought I shit the [garble].

133:29:02 Young (onboard): Yes.

133:29:30 Cernan (onboard): Yes, Tom; I don't know. I'm not averse to making to getting - you know, once you get out of lunar orbit, you can do a lot of things. You can power down, you can do a lot of things. [Garble] another fuel cell, we're going to be sucking a hind tit. And what's happening is...

133:29:44 Stafford (onboard): Oh - Who did it?

133:29:46 Young (onboard): Who did what?

133:29:47 Cernan (onboard): What?

133:29:49 Stafford (onboard): Who did it? (Laughter)

133:29:51 Cernan (onboard): Where did that come from?

133:29:52 Stafford (onboard): Give me a napkin quick, there's a turd floating through the air.

133:29:55 Young (onboard): I didn't do it. It ain't one of mine.

133:29:57 Cernan (onboard): I don't think it's one of mine.

133:29:59 Stafford (onboard): Mine was a little more sticky than that. Throw that away.

133:30:06 Young (onboard): God almighty.

133:30:08 SC (onboard): (Laughter).

133:30:10 Stafford (onboard): What do you see?

133:30:12 Young (onboard): Nothing, that's enough for me.

133:30:16 Cernan (onboard): Yes.

133:30:18 Young (onboard): Nice going there.

133:30:20 Cernan (onboard): No more turds are going to fit in there.

133:30:23 Stafford (onboard): Is that waste compartment full?

133:30:26 Young (onboard): No, hell; there's nothing in there.

133:30:28 Cernan (onboard): It goes all the way down to the...

133:30:30 Crew (onboard): (Laughter).

133:30:32 Cernan (onboard): Hell, when I got in there, I had to stick my hand in there and [garble] - He put it in the bag, didn't he? You guys been trying to stick it through there with your fingers?

133:30:40 Crew (onboard): (Laughter)

133:30:44 Stafford (onboard): OK. Soon as we get contact...

133:30:46 Cernan (onboard): Tom, what bothers me about this pump action is [garble]...

133:30:50 Stafford (onboard): There it goes. OK. Let's...

133:30:53 Cernan (onboard): this damn thing - I think it's the pump - is cycling on and off. It's not like it's set, set within limits. The son of a bitch is going on and off, on and off. How long is that going to last? It's like I'm watching the voltage going or something.

133:31:05 Stafford (onboard): From the fuel cell, too?

133:31:06 Cernan (onboard): No, I'm watching, the voltage go up and down, and I'm trying to correlate it with when the pump is going on and off and I can't, but almost.

133:31:19 Young (onboard): When do they pick us up? [Garble].

133:31:24 Stafford (onboard): Hey, What about this monocular?

133:31:27 Cernan (onboard): Here, is there some - Where does this thing go?

133:31:28 Stafford (onboard): Down below.

133:31:32 Cernan (onboard): John, do you know where this mother stows, by any chance?

133:31:35 Young (onboard): No.

133:31:37 Cernan (onboard): [Garble] know where it goes.

133:31:41 Stafford (onboard): 133:57. Got 25 more minutes.

133:32:11 Cernan (onboard): I just don't like that cycling pressure like that.

133:32:14 Young (onboard): Something peculiar going on there.

133:32:17 Stafford (onboard): We can limp home on one fuel cell, once we get out of orbit, here.

133:32:20 Young (onboard): Yes. We want to get out of orbit. I don't want to do that either.

133:32:29 Stafford (onboard): Well, we could - [fuel cell] 1 is still good, it can carry some load.

133:32:33 Cernan (onboard): Yes. We'll put 1 on the line, so you can find its - its temperature here. Get the pump back on.

133:32:45 Stafford (onboard): We got an H2 purge going on it full?

133:32:48 Cernan (onboard): Huh?

133:32:49 Stafford (onboard): We got an H2 purge going on it?

133:32:51 Cernan (onboard): No. No.

133:32:53 Stafford (onboard): Did it all come back into the normal spec.

133:32:55 Cernan (onboard): Yes, Yes. You'll have the - put a continuous H2 purge on it if you use it all the time, to keep it cool. What they're talking about is using it for burns. OK. Call up a Noun - a Verb 64.

[Verb 64 is used to call up Routine 5 to compute and display the two steerable S-band antenna gimbal angles which will point the High Gain Antenna towards the center of the Earth. Cernan is trying to get prepared for AOS, to try and get a good antenna lock-on as quickly as possible after acquisition.]

133:33:11 Stafford (onboard): OK. It'll be 25 minutes before we get them.

133:33:15 Young (onboard): Yes. Are we going to hold orb rate?

133:33:17 Stafford (onboard): Yes.

133:33:20 Cernan (onboard): I'm getting tired of watching this thing go up and down.

133:34:01 Cernan (onboard): Need some help up there, John?

133:34:03 Young (onboard): No. I got it, finally. Probably isn't exactly military in its stowage range.

133:34:14 Cernan (onboard): You want this?

133:34:16 Young (onboard): Yes.

133:34:26 Stafford (onboard): There it is.

133:34:30 Cernan (onboard): Man, I don't like that at all. Tom, you better put these in your pocket.

133:34:36 Stafford (onboard): Yes.

133:35:01 Stafford (onboard): We have a - a maneuver - a TEI maneuver for this time around, don't we?

133:35:13 Cernan (onboard): It's right now. Right now it's at 37.

133:35:20 Young (onboard): Well, shit.

133:35:23 Stafford (onboard): This is what - Yes, TEI, it's going to be right in the sunlight.

133:35:28 Young (onboard): Heads down.

133:35:30 Stafford (onboard): Inertial.

133:35:31 Young (onboard): What's your pitch angle?

133:35:32 Stafford (onboard): Oh, pitch angle is 055, so we...

133:35:34 Cernan (onboard): This one would be 054 and it's [garble], so you're at about the attitude.

133:35:39 Stafford (onboard): I'm at 054. You pitch down where the horizon is right - What time is it?

133:35:47 Young (onboard): I'm going to turn this off - the power switch off. What time are we - supposed to,,,

133:35:56 Stafford (onboard): 27. You get that stuff out of the way. John?

133:36:01 Young (onboard): Yes. It's all down out of the tunnel. Tunnel inspection, tunnel verified as clear.

133:36:08 Stafford (onboard): OK. That's the attitude.

133:36:13 Cernan (onboard): We were supposed to have had a waste water dump at 135.

133:36:16 Young (onboard): We should have?

133:36:18 Cernan (onboard): No, it's not yet, it's not that time yet, but do you want to do that now?

133:36:20 Stafford (onboard): Go ahead and do it.

133:36:21 Cernan (onboard): Just in case?

133:36:22 Stafford (onboard): Go ahead and do it. Then we won't have any particles back in it.

133:36:27 Young (onboard): 135.

133:36:30 Cernan (onboard): Same place, 2 hours from now. Let me look and see. I wrote it in there.

133:36:39 Young (onboard): Waste water-dump you can do anytime, even while you're burning.

133:36:44 Cernan (onboard): Tom. the waste water dump is 135.

133:36:47 Stafford (onboard): Let me have the camera. Have you got black and white?

133:36:53 Cernan (onboard): 135. [Garble]...

133:36:57 Stafford (onboard): [Garble] You got black and white?

133:36:58 Cernan (onboard): Yes.

133:37:31 Young (onboard): How often does the Master Alarm come on? Must be - We could time it.

133:37:37 Cernan (onboard): Once every 5 times. John, we're up to 80 per cent waste water. Do you want to dump it?

133:37:42 Young (onboard): OK. Is that a no-no?

133:37:46 Cernan (onboard): What?

133:37:48 Young (onboard): It says was 85 percent.

133:37:58 Cernan (onboard): That could be an 82 percent.

133:38:01 Young (onboard): Maybe that's part or our problem.

133:38:03 Cernan (onboard): That's what I was wondering. We've got to dump it in a rev hours anyway.

133:38:08 Stafford (onboard): That water may be backing up in the cell, huh?

133:38:11 Cernan (onboard): That's a remote possibility, but it's not - it's the temperature though.

133:38:19 Young (onboard): OK. Well, I'll dump it.

133:38:20 Cernan (onboard): Let's dump it.

133:38:21 Stafford (onboard): Ain't going to perturb my orbit here.

133:38:27 Young (onboard): Did they say we could do it anytime?

133:38:29 Cernan (onboard): They said on 135. They told us that - Here's another goddam turd. What's the matter with you guys'? Here, give me a...

133:38:37 Stafford & Young (onboard): (Laughter)

133:38:39 Cernan (onboard): Well, babe, if it was me, I sure would know I was shitting on the floor.

133:38:43 Stafford (onboard): It was just floating around?

133:38:45 Cernan (onboard): Yes.

133:38:47 Stafford (onboard): (Laughter) Mine was stickier than that.

133:38:52 Young (onboard): Mine was too. It hit that bag...

133:38:53 Cernan (onboard): When I stuck my finger in mine - mine was too soft. God dang.

133:39:01 Stafford (onboard): (Laughter)

133:39:03 Cernan (onboard): (Laughter) I don't know whose that is. I can neither claim it nor disclaim it (laughter).

133:39:09 Young (onboard): What the hell is going on here?

133:39:10 Cernan (onboard): I don't know. I - that's what I was up against when - (laughter) - After Tom stuck his in there, I figured, Jesus, how...

133:39:22 Young (onboard): Something wrong there. We're going to have to get all that crap out. It's supposed to go clean back over that [garble] there.

133:39:55 Young (onboard): OK, the dump is already dumping, huh?

133:39:59 Cernan (onboard): The dump is - is not doing anything.

133:40:04 Young (onboard): OK. You want me to go to Dump on 2?

[Young is referring to the operation of the water pressure relief valve on panel 352 used as part of the procedure for dumping waste water. He is asking whther Cernan wants him to move the valve to the 2 position, which directs the waste water to the No.2 pressure relief valve. With the valve set to this position, it provides automatic pressure relief of the waste water storage tank.]

Waste water tank pressure relief valve control P352

Waste water tank pressure relief valve control on panel 352.

(Click on the above diagram for a larger version.)

133:40:05 Cernan (onboard): Yes.

133:40:06 Young (onboard): OK, 2?

133:40:12 Cernan (onboard): Is it dumping?

133:40:13 Young (onboard): Yes.

133:40:14 Stafford (onboard): I think so. Looks like it's going down to me...

133:40:16 Cernan (onboard): Yes, there it. is. It's going out.

133:40:49 Stafford (onboard): Do we have any black and white left besides this MAG?

133:40:52 Cernan (onboard): [Garble].

133:40:58 Young (onboard): You what?

133:40:59 Cernan (onboard): [Garble].

133:41:26 Stafford (onboard): Well, I don't - there's Snoopy.

133:41:28 Young (onboard): Got him?

133:41:30 Stafford (onboard): You're damn right I - Oh, shit, do I have him. Get that monocular.

133:41:33 Young (onboard): Here it is.

133:41:34 Cernan (onboard): That's the same way he came up before.

133:41:38 Stafford (onboard): Where - where's the op - where's - Here, let me go to [garble]. Get the monocular on him, Gene-o.

133:41:51 Stafford (onboard): The COAS.

133:42:03 Cernan (onboard): Remember we got a waste-water dump going.

133:42:07 Young (onboard): So?

133:42:08 Cernan (onboard): So we don't dump it all.

133:42:13 Young (onboard): He's way up there.

133:42:14 Cernan (onboard): That's him alright. You can see his damn legs...

133:42:20 Young (onboard): Let me see - let me see.

133:42:22 Cernan (onboard): Let me take one quick peek.

133:42:26 Young (onboard): You have a sight on him?

133:42:28 Stafford (onboard): OK. We're on - Oh - he's starting to get lost on the Sun's [garble].

133:42:33 Cernan (onboard): No, you can see him. You can see his legs on...

133:42:35 Stafford (onboard): He passed down below us. Maybe he's going up and behind us.

133:42:38 Cernan (onboard): He's still going out but you...

133:42:39 Stafford (onboard): OK. Let's stand by to take some data, just for the heck of it. OK, babe?

133:42:43 Cernan (onboard): Alright. Give me some GET...

133:42:44 Stafford (onboard): I want - OK...

133:42:46 Cernan (onboard): ...give me a - turn the GET time on...

133:42:48 Stafford (onboard): I've got it full bright - you'll have to hold your hand and shade it.

133:42:50 Cernan (onboard): OK.

133:42:51 Stafford (onboard): I'm going to track him optically.

133:42:53 Young (onboard): I don't see him...

133:42:54 Cernan (onboard): Give me a Mark.

133:43:02 Stafford (onboard): Stand by.

133:43:09 Young (onboard): Let me see if I can put the optics on him. Gene-o.

133:43:10 Stafford (onboard): Stand by...

133:43:12 Stafford (onboard): Mark.

133:43:13 Young (onboard): Let me put the optics on him.

133:43:14 Cernan (onboard): What do you get for an angle. Tom?

133:43:16 Young (onboard): Let me put the optics on him. Tom.

133:43:17 Stafford (onboard): Mark.

133:43:18 Stafford (onboard): Inertial, in orb rate - orb rate, he is 3 - 350.

133:43:23 Young (onboard): There ain't [garble] inertial will get him.

133:43:26 Stafford (onboard): You Mark; he was 350 at that time.

133:43:28 Cernan (onboard): Let John track him with the optics.

133:43:30 Young (onboard): Yes. pitch up and get him with the optics...

133:43:31 Stafford (onboard): OK. You got some Sun out there. babe. He's going out.

133:43:36 Young (onboard): Oh, OK.

133:43:37 Stafford (onboard): Now he looks a little out of plane - a couple of degrees. on the bellyband. What's he look like to you. babe? OK. I got him 12 degrees below the X-axis. John.

133:44:08 Cernan (onboard): No question about - about what it is, I'll tell you.

133:44:13 Young (onboard): You got him 12 degrees below the X-axis?

133:44:14 Stafford (onboard): Yes.

133:44:11 Young (onboard): Oh, shit. I turned the optics off. Here comes the optics back on - Watch - watch it. I got him - I got him - I got him!

133:44:21 Stafford (onboard): OK. OK. Start tracking him. Well, if we start our TEI, we're going to be climbing out like mad, see? And he's going to be up above us, and we'll be going right through that thing.

133:44:54 Cernan (onboard): That's right. We would have fired TEI [garble] minutes ago.

133:44:58 Stafford (onboard): You damn right...

133:44:59 Young (onboard): Snoopy.

133:45:00 Cernan (onboard): Huh?

133:45:01 Young (onboard): I got him.

133:45:11 Stafford (onboard): Shit. I could nearly see his legs from here.

133:45:13 Cernan (onboard): I know it.

133:45:14 Young (onboard): I can't see any legs from here. He must be a long ways off.

133:45:17 Stafford (onboard): You can't in the scope?

133:45:19 Young (onboard): Yes. I cannot.

133:45:20 Stafford (onboard): You cannot.

[The Apollo optical navigation telescope is a unity-power instrument and hence provides no magnification.]

133:45:22 Young (onboard): [Garble] the tunnel for a bit - babe. Goddamn it, P20; knock that shit off. I got him. Hold what you got, TP.

[Young has been trying to use Program 20 in option 4. This option is used to acquire the LM in the sextant field of view. Having acquired the LM descent stage he now wants Stafford to maintain the current attitude rather than let the CMC drive the auto-optics.]

133:45:34 Stafford (onboard): OK.

133:45:39 Young (onboard): You sure that's him out there?

133:45:40 Stafford (onboard): Babe, that's got to be him.

133:45:43 Young (onboard): I think that is a planet.

133:45:44 Stafford (onboard): Huh?

133:45:45 Cernan (onboard): That's him, babe. No, that's him.

133:45:56 Young (onboard): Oh, look at this freaker calculate.

133:46:06 Stafford (onboard): That ain't no planet, John, baby.

133:46:12 Young (onboard): Well, I don't know what the hell it...

133:46:19 Stafford (onboard): He isn't that far out there.

133:46:21 Young (onboard): Looks like a planet.

133:46:24 Stafford (onboard): It couldn't be, John.

133:46:25 Cernan (onboard): It couldn't be, John. We've seen him go in reflected sunlight and disappear...

133:46:29 Stafford (onboard): Yes, but - what was - that wasn't no planet going down below us like a scalded...

133:46:31 Cernan (onboard): No, and that's exactly where he'd be.

133:46:48 Young (onboard): Now a Verb 37 [garble]. OK. OK. Let's just get some accurate GET time - time hacks on his position.

[Verb 37 is used to change between programs.]

133:47:11 Stafford (onboard): OK. Stand by. Gene-o, got the clock ready to mark?

133:47:20 Young (onboard): I - I don't know - I - There's no way - there's no way for me to...

133:47:25 Stafford (onboard): Babe, that isn't any planet, I'll clue you. He's got dimensions to him.

133:47:28 Cernan (onboard): That's right; he does...

133:47:29 Young (onboard): I tell you...

133:47:30 Cernan (onboard): ...he's tumbling [garble]...

133:47:31 Stafford (onboard): Can you track him...

133:47:32 Young (onboard): Have you got the...

133:47:33 Cernan (onboard): ...tumbling in the sextant. You ought to see it through the monocular.

133:47:38 Stafford (onboard): I'm trying to say he's out of plane here, but the odd here. He's pitching up all the time, going above us.

133:47:48 Cernan (onboard): OK. John. I'm ready to record some marks on time...

133:47:51 Young (onboard): My God. I don't have any state vector or nothing I can't. Well, let me do it this way.

133:48:03 Stafford (onboard): Well, I could - I could put the X-axis on him and track local horizontal. and it can get something from there.

133:48:10 Young (onboard): Oh, shit; that'll lock the freaking computer up.

133:48:14 Cernan (onboard): Still got him. Tom?

133:48:15 Stafford (onboard): Oh, you better believe I've got him.

133:48:16 Cernan (onboard): Sun's in my eyes. I can't see him.

133:48:19 Young (onboard): Well, hell...

133:48:20 Cernan (onboard): Doesn't he look like he's tumbling to you. Tom?

133:48:23 Young (onboard): ...let's just stay in this attitude, until we get to the ground.

133:48:26 Stafford (onboard): Huh?

133:48:27 Young (onboard): When are we going to get ground contact?

133:48:28 Cernan (onboard): In about...

133:48:30 Stafford (onboard): You ought to - I'll stand by to put the plus-X on him. You can't do any good marking on him inertially, can you?

133:48:38 Young (onboard): Well - but wait a minute...

133:48:39 Cernan (onboard): ...10 minutes, John.

133:48:40 Young (onboard): ...the ground can read this stuff. They can figure out just where he is.

133:48:41 Stafford (onboard): OK.

133:48:42 Young (onboard): They can read our platform angles and his. I'll just stay here - I'll just keep this on him. When are we supposed to come in contact with them?

133:48:49 Cernan (onboard): Give me a Verb 64. 10 more minutes.

[Once again Cernan wants the CMC to calculate the high-gain antenna pointing gimbal angles in preparation for AOS.]

133:48:53 Stafford (onboard): I don't...

133:48:54 Young (onboard): OK. You got to pitch up some more, Tom.

133:48:55 Stafford (onboard): OK.

133:49:09 Young (onboard): He's going up above us, now. I'm not sure it's not a planet.

133:49:13 Cernan (onboard): Shoot, you can see the shades of reflection off him when he tumbles through that monocular.

133:49:17 Young (onboard): He's not tumbling in the optics. It looks like Venus or something like that...

133:49:21 Stafford (onboard): Is that right? It could be.

133:49:24 Cernan (onboard): I don't know how you can see Venus with it looking right up at that Sun. Oh. you're not looking at the Sun, though.

133:49:28 Young (onboard): Well, that's the thing of it. The Sun - the Sun is - shades Venus. It's either Venus - I think it's Saturn, is what I think it is. Why don't we knock this off? It's going to be embarrassing.

133:49:46 Stafford (onboard): (Laughter) Yes. He's sure got dimension. Well, there's no doubt that that was Snoop when we saw him going down below us.

133:49:58 Cernan (onboard): [Garble] nothing else could [garble]...

133:49:59 Young (onboard): Yes. Well, I'll agree with that. I just don't believe - I just don't believe that's him.

133:50:03 Stafford (onboard): Yes. I - I think you're probably right.

133:50:07 Young (onboard): Why don't we knock it off?

133:50:08 Stafford (onboard): Yes. I'm with you, babe.

133:50:11 Young (onboard): Because he's - this is definitely out to one side.

133:50:14 Stafford (onboard): Yes. Well, OK; but I'm yawed a little bit, too.

133:50:17 Young (onboard): Well, he's worse when you yaw back.

133:50:25 Stafford (onboard): Well, what we have here is out of plane, definitely. We've never seen anything...

133:50:28 Young (onboard): Yes. It ain't even close.

133:50:30 Cernan (onboard): Can't you call up Venus or Saturn on the Auto Optics and find out?

133:50:39 Young (onboard): I could if I knew what the freak the numbers were.

133:50:47 Stafford (onboard): Yes. He - it's out of plane - that's the plane of the ecliptic there. Yes, that thing would never bother us. It's over and to the left.

133:51:00 Young (onboard): I don't think that's him.

133:51:02 Cernan (onboard): Maybe you're right. I don't know.

133:51:05 Young (onboard): I think it's Saturn or Venus, one.

133:51:09 Stafford (onboard): Now it isn't sparkling...

133:51:10 Young (onboard): Probably Saturn.

133:51:11 Stafford (onboard): it isn't sparkling like it was before. But that was the real living, breathing Snoopy that we saw going down below us (laughter).

133:51:24 Young (onboard): Maybe even [garble].

133:51:29 Stafford (onboard): Yes, that was trailing the sun right through. It's got a different color - it doesn't have the orange color like...

133:51:35 Young (onboard): Yes. You guys, when you - when you're out there, you look like a star (cough). Looks like I'm tracking a damn star (cough) in the daytime.

133:51:44 Stafford (onboard): Well, I wouldn't sweat what we've got here. He's out of plane. You know, that could have been probably what we saw before - then picked up Snoopy other than that, and then tried to extrapolate it.

133:52:26 Young (onboard): Maybe.

133:52:30 Cernan (onboard): (Cough).

133:52:40 Young (onboard): What time are we supposed to do this landmark shit - stuff'?

133:52:45 Stafford (onboard): We got a ways to go. We got B-1 which is way down in landing site 1. We've got...

133:52:49 Cernan (onboard): Got a waste-water dump, John.

133:52:51 Young (onboard): Huh?

133:52:52 Cernan (onboard): Waste-water turn-off.

133:52:54 Young (onboard): Did you turn it off?

133:52:57 Stafford (onboard): Did we dump too much?

133:52:58 Cernan (onboard): About 20 percent.

133:53:40 Cernan (onboard): Done with your optics? Why don't you turn them off?

133:53:49 Young (onboard): Which amp does that bias?

133:53:50 Cernan (onboard): Turn off the optics...

133:53:51 Stafford (onboard): I got - I got my GDC I'll do.

133:54:01 Cernan (onboard): Did you say something?

133:54:02 Young (onboard): Which amp does that bias, turning off the optics?

133:54:06 Cernan (onboard): I'd expect the amps gives you about a quarter of a volt count. Quarter - sometimes a half, at least.

133:54:14 Young (onboard): OK. That O2 flow is fluctuating plenty, isn't it?

133:54:17 Cernan (onboard): It's fluctuating at both cells.

133:54:22 Young (onboard): Has it been doing that before? Huh?

133:54:26 Cernan (onboard): No. It hasn't been doing that before.

133:54:35 Young (onboard): How about this cryogenic tank things?

133:54:38 Cernan (onboard): [Garble] configuration I gave it a while ago, and we're still alright there.

133:55:00 Stafford (onboard): 1 minute after TEI we can shut off the ORDEAL and pull the ORDEAL breakers and stow that box, because it isn't going to help us any more.

[ORDEAL is used to drive the FDAI in the pitch axis only whilst the spacecraft is in orbit around Earth or the Moon, therefore it will have no further function once TEI has been performed.]

133:55:10 Young (onboard): That's right. We got the waste water off, didn't we?

133:55:21 Cernan (onboard): Call up Verb 64 for me; we're getting close to them now.

[Yet again Cernan needs the CMC to give him the High Gain Antenna pointing angles. He is keen to get good communications as he needs to advise MCC-H about the issue that has become apparent with fuel-cell 2 condenser exhaust temperature fluctuations.]

133:55:24 Stafford (onboard): I don't think we can get them with that - this side up.

133:55:30 Young (onboard): What about the [garble]?

Air-to-ground audio

133:56:XX PAO: This is Apollo Control at 133 hours, 56 minutes. We're now about 50 seconds from reacquiring Apollo 10, now in its 30th revolution of the Moon. Coming up on this revolution, the crew will be involved in some landmark tracking exercises and also will be taking photographs of targets of opportunity. As you heard on that previous revolution, Tom Stafford reported that he had taken a large number of pictures and that the onboard film supply was running low. So we don't anticipate a great deal of photography out of this revolution. We'll stand by now to reacquire the spacecraft in about 10 seconds.

133:56:26 Cernan (onboard): Yes, I know what - don't know what it means coming out of' orbit 2 hours earlier, but I sure - I just don't like all these fluctuations.

133:56:34 Stafford (onboard): It doesn't land you that much earlier. And - before sunrise.

133:56:46 Stafford (onboard): Yes, you'd rather have these problems on the way home (laughter).

133:56:48 Cernan (onboard): On the way home, where you can power the son of a bitch down and don't have to worry about it. But this type of thing - OK, we're coming in now.

133:57:00 Stafford (onboard): Here comes the Earth. Beautiful. We'll get him on Omni. We won't have any High Gain.

133:57:07 Cernan: Hello, Houston. Houston, this is Apollo 10. Over.

133:57:15 Young (onboard): I'm just now getting him.

133:57:16 Engle: Roger, Apollo 10. Reading you loud and clear. Go ahead.

133:57:22 Cernan: Hey, Joe, we got another little fuel cell problem we want to throw at you, fuel cell 2.

133:57:28 Engle: Roger. Go.

133:57:33 Cernan: The condensor exhaust temperature is cycling on fuel cell 2 between the ... about 155 degrees about. It's cycling 2 cycles per minute. It's been doing this for at least the last 30 or 40 minutes. And one in every 10 cycles it rings the Master Alarm for module exhaust temperature on fuel cell 2. In addition, I guess maybe we are seeing things we haven't before, but on fuel cell 2 and 3 the O2 flow rate dips to - the gauge, it keeps bobbling up and down just maybe 0.01 or so but just enough so the needle went up and down so flow rate ran continuously on both fuel cells. Over.

133:58:24 Young (onboard): That may be normal. Did - you never noticed that before?

133:58:26 Cernan (onboard): No. They bounce - they go up, then they bounce.

133:58:27 Engle: OK, 10. We copied everything except the band that the temperature is cycling between. It's between 155 and Something. What was the other number?

133:58:40 Cernan: It's between about 173 and about 155. It's cycling right in the green band at 2 cycles per minute and rings the Master Alarm on the low side about 1 every 10 cycles.

133:58:56 Engle: OK. Thank you, Gene-o. We copied all that.

133:59:51 Engle: OK, 10. This is Houston. We'll monitor...

133:59:55 Cernan: And Houston, this is...

133:59:57 Engle: Go ahead, Gene.

133:59:58 Cernan: Go ahead, Joe. No, you go ahead.

133:59:59 Stafford (onboard): Call over.

Flight Plan

134:00:01 Cernan (onboard): He's waiting.

134:00:03 Engle: OK. We'll monitor that fuel cell down here the best we can and keep us advised if anything new happens. Also, did you get a chance to look for Snoopy on the back side of the sunrise?

134:00:08 Cernan (onboard): Well. thanks a freaking lot.

134:00:15 Stafford: No. We looked up there, but as soon as the Sun comes up, it blanks everything and it's real funny. We had a planet to spot to the right and above Snoopy, but the phasing was wrong and we didn't see him at all.

134:00:30 Engle: OK. We copied that, Tom. Go ahead, Gene. You were going to say something.

134:00:36 Cernan: I was going to say we got our water dump out of the way a little bit early. We dumped it about 15 minutes ago.

134:00:44 Engle: OK. I copied that. We got a power configuration for TEI burn with respect to this fuel cell. Now, this is with the original fuel cell problem; we may want to change it some if we've got another problem. But if you'd like to copy this down, I'll read off this configuration for you.

134:01:05 Cernan: Go ahead. And believe it or not, it looks like that condenser exhaust temperature cycle has now closed its band down to be about plus or minus 10 degrees, well within the green band, just as we came on here, within the last 5 minutes.

134:01:22 Engle: OK. That sounds real good. We'll still keep a good close eye on it for you. On this configuration for the TEI burn, this will be for 136 hours. We'd like for you to verify that fuel cell 1 pumps are Off on panel 5, and prior to the TEI burn, at approximately 136 hours, place fuel cell 1 on both main buses. And after the TEI burn, take number 1 fuel cell off main A, main B buses whenever it's convenient.

134:01:56 Young (onboard): How much prior? Did he say? Did he say how much prior to the burn to put it on?

134:02:03 Cernan: You want it On the half hour before - an hour and a half before the burn; is that correct?

134:02:08 Engle: That's affirmative, Gene.

134:02:14 Cernan: OK. Do you want Fuel Cell 1 Pump, Off now?

134:02:15 Stafford (onboard): It's been Off.

134:02:17 Young (onboard): No, it ain't been Off.

134:02:21 Stafford (onboard): Thought they couldn't set the circuit breaker.

134:02:23 Engle: OK Gene, the circuit breaker for 1 is open now, is that affirmative.

134:02:32 Cernan: That's affirmative, but the switch according to what I'm reading here, it says the switch must be On to enable power for power factor correction, is that correct?

134:02:44 Engle: You're coming through a little scratchy.

134:02:47 Cernan: [Garble] fuel cells according to what I'm reading. As long as you're going to use the fuel cells for the burn what I read here is that the pump switch for fuel cell 1 and or 3 should be left On for power factor correction.

134:03:06 Young (onboard): Is that High Gain?

134:03:10 Stafford (onboard): [Garble] might be able to get him now.

134:03:15 Engle: OK, Gene. I think, if I read you correctly, if we understand what you mean, we're not going to try and activate the pump during the TEI burn. We're going to leave it turned off. So you can leave that switch at whatever it is now, if you like...

134:03:33 Young: Let's leave it alone.

134:03:34 Engle: ...The circuit breaker is pulled. We're just going to bring the fuel cell - we're going to activate the fuel cell. We won't turn the pump on.

134:03:41 Cernan: I'm with you. We cannot turn the pump on because the circuit breaker will not reset. I'm referring primarily to the switch, and I'll leave it - it's been in the AC-1 position. We never did turn it off after the circuit breaker popped. And unless you have anything other I'll just leave it there.

134:03:59 Engle: That will be fine, Gene; just leave it where it is. It's inactivated now, anyway.

134:04:04 Young (onboard): That ain't what the freaking malfunctions...

134:04:06 Cernan (onboard): [Garble] power [garble] the Fuel Cell's On.

134:04:12 Young (onboard): OK. Let me see if I can get him on the High Gain.

134:04:16 Stafford (onboard): OK. When is the landmark tracking?

134:04:23 Young (onboard): Got it in the Flight Plan?

134:04:39 Stafford (onboard): Thank you.

134:04:45 Young (onboard): 133:50. Maneuver to landmark track attitude?

134:04:52 Stafford (onboard): Yes. We've been in landmark track attitude.

134:04:55 Young (onboard): OK. Where's the PAD?

134:05:02 Cernan: Say, Houston, do you read us on the High Gain? We're getting a semi-strong signal.

134:05:03 Stafford (onboard): 134:15.

134:05:07 Engle: Roger. We're reading you, 10.

134:05:12 Cernan: OK. I'll stay here then.

134:05:13 Stafford (onboard): Yes.

134:05:14 Engle: OK.

134:05:18 Cernan: OK. It looks like that oscillation on the condenser exhaust temperature, fuel cell 2, has damped out, believe it or not. But I timed it, and it was going 2 cycles per second throughout the region and, as I said, triggering the Master Alarm on fuel cell 2, but it's stable now.

[With the spacecraft having now been back in sunlight for several minutes, the condenser exhaust temperature has stabilized somewhat.]

134:05:33 Stafford (onboard): Per minute or per second?

134:05:35 Cernan (onboard): Per minute.

134:05:36 Stafford (onboard): You said second.

134:05:38 Engle: OK.

134:05:40 Cernan: That was 2 cycles - that was 2 cycles per minute Joe.

134:05:48 Engle: OK. We were monitoring some of that oscillation down here but we didn't see quite the width of oscillation that you were seeing, Gene.

14:05:57 Cernan: OK. I just took it right off the gauge here, and that's why I wanted to let you take a look at it now.

134:06:03 Engle: OK. And 10 this is Houston, you can...

134:06:05 Stafford (onboard): Where's the monocular?

134:06:08 Engle: ...terminate your battery B charge now if you want to.

134:06:10 Cernan (onboard): OK.

134:06:18 Stafford (onboard): That is Snoopy.

134:06:19 Young (onboard): Where you got him?

134:06:21 Stafford (onboard): Right in front; going down. Take a look.

Air-to-ground audio

134:06:30 Stafford: Houston, this is 10 again. It looks like I may - like - I've got Snoopy right out in front of me again. There's something going down just went by us. It just went down below. You can see [garble] a bright - 30 seconds ago he was at 350 pitch.

134:06:47 Young (onboard): Could that be that piece of Mylar wrapping that fell off?

134:06:51 Stafford (onboard): Yes. It could be...

134:06:53 Engle: OK, Tom. You're breaking up a little bit. I understand about 30 seconds ago he was ahead of you. Say again the pitch angle?

134:07:00 Stafford: Roger. The pitch angle was 350. Again, it could be a big hunk of Mylar wrapping. That's the only thing I can think of that would cause a reflection. We had a big hunk of our insulation blow off. It was with us for a while, and now it's disappeared completely down in the maria area. We'll keep looking for him.

134:07:22 Engle: Roger, Tom.

134:07:30 Stafford: In reflected sunlight it's awful hard to tell exactly the distance or dimension of anything. Over.

134:07:36 Engle: Roger. Understand, Tom.

134:07:41 Stafford (onboard): Phew! OK, John.

134:07:42 Young (onboard): See if this is the right numbers, Tom.

134:07:44 Stafford (onboard): OK. 02522, 17518, minus 0154. You got it. babe. OK. It'll be at 15:56. You got - nearly 8 minutes.

134:08:06 Young (onboard): 8 minutes. OK, optics power's coming back on.

134:08:24 Young (onboard): [Garble] those out the side window. I guess.

134:08:21 Stafford (onboard): Yes. Why don't you...

134:08:28 Cernan (onboard): [Garble] damn fuel cell. I don't understand why the son of a bitch stopped. [Garble].

134:08:53 Cernan (onboard): You got the camera, Tom?

134:09:00 Young (onboard): [Garble].

134:09:04 Stafford (onboard): Yes. I shot a bunch of them. It came off the Velcro. Here we go.

134:09:24 Young (onboard): Now, do we do a realign just before TEI - or no? We do this - we do one after this and then we come around TEI...

134:09:33 Cernan (onboard): No. I don't think we do one after this. I looked for one after this. I didn't see any...

134:09:35 Stafford (onboard): We don't do one after this.

134:09:37 Young (onboard): OK. So this next one will be a good one. Of course, this one here's - this one here's a good one. We could do TEI with this...

134:09:43 Stafford (onboard): Sure.

134:09:44 Young (onboard): we got right here. No sweat.

134:09:48 Stafford (onboard): You know, that could be that hunk of Mylar insulation, that big yellow hunk that drifted out there - but I don't think it'd show that much.

134:09:56 Young (onboard): Yes. It wouldn't be bright.

134:09:59 Cernan (onboard): We're going forward. If he's coming down. he's way out in front of us now.

134:10:07 Stafford (onboard): In orbital mechanics, if he was that close underneath us, you'd have to be behind [garble]. If you'd pass under once you pass under us in that type of orbit, he'd go way under us.

134:10:24 Cernan (onboard): Maybe there's some other things up here we don't know about.

134:10:30 Young (onboard): Come on, now. How much time is it, 5 minutes? What's the pitch over time. Tom?

134:10:46 Stafford (onboard): 5 minutes.

134:10:48 Young (onboard): I mean the...

134:10:49 Stafford (onboard): Zero time - Let me - Where's the - 34:15:56.

134:10:53 Cernan (onboard): Just take side oblique. Is that all that thing says. Tom?

134:10:58 Stafford (onboard): Yes. Configure camera for descent strip photography.

134:11:07 Cernan (onboard): Does it say start taking [garble]?

134:11:18 Young (onboard): Is that the right number? Yes. 25 [garble] There we go. Jesus Christ, I don't know what - OK. He's north of ground track, so don't roll at all, Tom.

134:11:38 Stafford (onboard): Yes.

134:12:15 Cernan (onboard): Strip photography beginning at 90 degrees East and continuing to the terminator. Spacecraft is yawed 20 degrees off at the vertical at 85 degrees East. We center Censorinus at the approach path in the strip maneuver - strip, and maneuver back to vertical at 30 degrees to center landing site, site 3, and its approach path in the strip. Son of a bitch; you got a lot of stuff to do here, babe.

134:12:41 Cernan (onboard): Hey, we are at 90 degrees east and we're still on target. How the hell are we doing landmark? How...

134:12:45 Stafford (onboard): That's a rev later - rev later - rev later...

134:12:48 Cernan (onboard): 135; you're right. I'm sorry. I'm sorry.

134:13:00 Stafford (onboard): OK. You got 2 minutes - nearly 3 minutes. John.

134:13:12 Young (onboard): Shit. this freaking map is worthless!

134:13:18 Stafford (onboard): OK. I got Mount Marilyn up here, babe, and the crater Weatherford.

134:13:45 Young (onboard): Hell, there we are. There's the Taruntius - Secchi and Secchi B. Secchi A and B. We just went between them. Taruntius F and its friend - OK. Starting to look pretty good, Tom.

134:13:45 Stafford (onboard): I've got the five diamond craters that leads into landing site 1. Well, we've got beaucoup shots of this, haven't we?

134:13:57 Cernan (onboard): Yes. [Garble].

134:14:01 Young (onboard): Yes. I got them.

134:14:02 Engle: Apollo 10, Houston.

134:14:08 Stafford: OK. We're right near B-1 for this mark. Go ahead; keep it short. Over.

134:14:15 Engle: I've got a maneuver PAD. Give me a call when you're ready to copy, Tom. I'm sorry.

134:14:22 Stafford: Roger.

134:14:31 Stafford (onboard): OK. John, at 17:30 is when we'll...

134:14:47 Young (onboard): We got a ways to go yet. Tom.

134:14:50 Stafford (onboard): This one is probably pretty easy to see, isn't it?

134:14:54 Young (onboard): Well, I don't know - Shit to tell you the truth...

134:15:02 Stafford (onboard): I've got it out there.

134:15:08 Cernan (onboard): You know, can you tell me why that thing's settled down?

134:15:12 Stafford (onboard): Beats the heck out of me, Gene-o.

134:15:15 Cernan (onboard): Even the oxygen has started - stopped its fluctuation.

134:15:20 Young (onboard): T.P. started shaking - stopped shaking the spacecraft.

134:15:24 Stafford (onboard): OK. It's, going to be out to the north of track. There's no doubt about that. I can see it, babe.

134:15:38 Young (onboard): OK. It's coming down.

134:15:40 Stafford (onboard): Yes.

Air-to-ground audio

134:16:27 Young (onboard): Go get them.

134:16:30 Stafford (onboard): OK. 17:30 is when you - Got about another minute to go, John.

134:16:35 Young (onboard): OK, there's the stars. Those freakers on here?

134:17:11 Young (onboard): This map is sh - crappy!

134:17:14 Stafford (onboard): OK.

134:17:17 Cernan (onboard): Censorinus has got all that white stuff right in the - Boy, there's a silly-reading mother.

134:17:22 Stafford (onboard): OK. 15 seconds, John.

134:17:24 Young (onboard): OK. I got it:

134:17:30 Stafford (onboard): OK. About another 15 or so - whenever you get ready, babe, you can go ahead and hit it. Give me a mark.

134:17:37 Young (onboard): OK.

[Crew are marking on landmark B-1.]

Landmark B-1

Landmark B-1 in southern Mare Tranquillitatis, near landing site 1.

(Click on the above image for a larger version.)

134:17:48 Stafford (onboard): Mark.

134:17:51 Young (onboard): OK

134:17:59 Stafford (onboard): 10 seconds. 20 seconds. 25 seconds. 30 seconds.

134:18:20 Stafford (onboard): Mark.

134:18:21 Stafford (onboard): That's two of them. 5, 10, 15, 20, 25, 30. 5...

134:18:57 Young (onboard): Pitch down some, Tom.

134:19:00 Stafford (onboard): ...10, 15, 20, 25. That's four of them. 5...

134:19:25 Young (onboard): Didn't get it.

134:19:28 Stafford (onboard): Didn't get it?

134:19:29 Young (onboard): No. There are four good marks, though.

134:19:35 Stafford: OK, Houston. Go ahead with your maneuver PAD.

134:19:34 Cernan (onboard): Wait a minute - wait a minute - wait a minute! We're not ready.

134:19:40 Engle: Roger, 10, this will be...

134:19:41 Stafford: Stand by.

134:19:43 Engle: OK. I'm standing by.

134:19:47 Stafford: OK. We're in between B-1 and Site 3. Over.

134:19:49 Young (onboard): You know, I don't think we have very much time to make this shift either.

134:19:52 Stafford (onboard): 27 [garble]...

134:19:52 Engle: OK. Do you want me to hold off on this pad, Tom?

134:19:56 Cernan: Go ahead, Joe.

134:19:57 Stafford (onboard): Yes, we do.

134:19:59 Stafford (onboard): Well, hell, we got...

134:20:00 Engle: Roger. TEI 31, SPS/G&N: 36685, minus 062, plus 089; 137:36:28.20; plus 36255, plus 00401, plus 01889; 181, 051, 002 NA, plus 0021.2; 36306, 2:41, 36079; 16, 146.4, 29.4. The next three are NA. Noun 61: minus 15.08, minus 165.00; 1203.8, 36394, 191:50:43. Your stars are Deneb 43, Vega 36; 241, 240, 013. For ullage: two quads with 14 seconds; and use quads Bravo and Delta. Horizon on 6-degree window mark at ignition minus 1 minute...

134:22:55 Stafford (onboard): Right.

134:22:56 Young (onboard): Good.

134:22:59 Engle: ...Sextant star not available until 137:06:00. Sun not visible in COAS at ignition. Horizon will be lit at ignition. That's the end, and I'll stand by for your readback.

134:23:33 Stafford (onboard): Hang on for just a minute. OK, John. At 27:40, you should pick up 150 and at 29: 12. So you got about 4 minutes. OK?

134:23:46 Young (onboard): Yes,

134:23:48 Stafford (onboard): You can read it back real fast.

134:23:52 Young (onboard): Can you check these numbers here, Tom?

134:23:53 Stafford (onboard): OK. I'll check the numbers. 00283, minus -That's plus on that first one - minus 00714, and a minus 00105. Got it?

134:24:05 Cernan (onboard): Yes. Roger.

134:24:08 Stafford (onboard): You can read it back...

134:24:11 Cernan: OK, Joe. Give me Noun 47 again, and then I'll read it back.

134:24:16 Engle: You want Noun 47?

134:24:21 Cernan: Yes. The first number, the weight.

134:24:23 Engle: Roger that. 36685.

134:24:33 Cernan: OK. That's TEI-31, SPS/G&N: 36685, minus 0.62, plus 0.89; 137:36:28.20; plus 36255, 00401, plus 01889; 181, 051, 002. Apogee is NA; perigee is plus 0021.2; 3606, 2:41, 36079; 16, 146.4 29.4. Noun 61 is minus 15.08, minus 165.00, plus 12038...

134:25:09 Stafford (onboard): It's right on the ground track...

134:25:10 Cernan (onboard): Noun 61 is minus...

134:25:11 Young (onboard): [Garble] 10 degrees?

134:25:12 Cernan (onboard): ...15.08...

134:25:13 Stafford (onboard): 2 miles.

134:25:14 Cernan (onboard): ...minus 165.00...

134:25:15 Stafford (onboard): North.

134:25:16 Young (onboard): OK. Roll right.

134:25:17 Cernan (onboard): 1203.8...

134:25:18 Young (onboard): How much?

134:25:19 Young (onboard): Right - 10.

134:25:20 Cernan: ...36394, 191:50:43. Deneb 43, Vega 36, 241 240013, 2 jets, 14 seconds plus Bravo and Delta. Horizon is on window [garble] the horizon is on the 6-degree window mark at TIG minus 1 minute. Sextant star not available until 137:06:00. Sun not visible in COAS at TIG and horizon is lit.

[This PAD represents all the information the crew need to burn their engine and begin their return path to Earth. A fuller interpretation of the PAD follows:
Purpose: This PAD will be used for TEI-31 Return-to-Earth burn.
Systems: The burn would be made using the SPS (Service Propulsion System) engine under the control of the Guidance and Navigation system.
CSM Weight (Noun 47): 36,685 pounds (16,640 kg).
Pitch and yaw trim (Noun 48): -0.62° and +0.89°.
Time of ignition, TIG (Noun 33): 137 hours, 36 minutes, 28.20 seconds.
Change in velocity (Noun 81), fps (m/s): x, +3,625.5 (+1,105.1); y, +40.1 (+12.2); z, +188.9 (+57.6). These velocities are expressed with respect to the Local Vertical/Local Horizontal frame of reference of the Moon.
Spacecraft attitude: Roll, 181°; Pitch, 51°; Yaw, 2°. The desired spacecraft attitude is measured relative to the alignment of the guidance platform which itself has been aligned to the lunar lift-off REFSMMAT.
HA, expected apogee of resulting orbit (Noun 44): Not applicable. The spacecraft will be on a trajectory coming from the Moon so any apogee figure would be meaningless.
HP, expected perigee of resulting orbit (Noun 44): +21.2 nautical miles (+39.3 km). The perigee distance is so low, it intersects the Earth's atmosphere. In other words, the spacecraft will re-enter.
Delta-VT: 3,630.6 fps (1,106.6 m/s). This is the total change in velocity the spacecraft would experience. (It is a vector sum of the three components given above.)
Burn duration or burn time: 2 minutes, 41 seconds.
Delta-VC: 3,607.9 fps (1,099.7 m/s). The crew enter this figure into their EMS Delta-V counter display. The EMS can shut down the engine using this data if the G&N system fails to do so. Its value is lower to allow for the extra thrust imparted by the engine after shutdown, a quantity allowed for the the G&N software but not by the EMS.
Sextant star: Star 16 (Procyon, Alpha Canis Minoris) visible in sextant when shaft and trunnion angles are 146.4° and 29.4° respectively. This is part of an attitude check.
The next three items are not applicable because the COAS will not have a clear view to the stars.
The next five parameters all relate to re-entry, during which an important milestone is "Entry Interface," defined as being 400,000 feet (121.92 km) altitude. In this context, a more important milestone is when atmospheric drag on the spacecraft imparts a deceleration of 0.05 g.
Expected splashdown point (Noun 61): 15.08° south, 165.00° west; in the mid-Pacific.
Range to go at the 0.05 g event: 1,203.8 nautical miles. To set up their EMS (Entry Monitor System) before re-entry, the crew need to know the expected distance the CM would travel from the 0.05 g event to landing. This figure will be decremented by the EMS based on signals from its own accelerometer.
Expected velocity at the 0.05 g event: 36,394 fps. This is another entry for the EMS. It is entered into the unit's Delta-V counter and will be decremented based on signals from its own accelerometer.
Predicted GET of 0.05 g event: 191 hours, 50 minutes and 43 seconds GET.
GDC Align stars: Stars to be used for GDC Align purposes are Deneb and Vega. The align angles are roll, 241°; pitch, 240°; yaw, 13°.
The ullage burn to settle the contents of the propellant tanks is to fire two RCS (Reaction Control System) quads (B&D) for 14 seconds.
Other notes include the fact that at the correct attitude for the burn and one minute to ignition, they should expect the Moon's horizon to line up with the 6° mark on the left rendezvous window; and the sextant star does not rise above the local horizon until after 137:06:00 GET.]

134:26:00 Engle: That was a real good readback, Gene. That was a full one, too. We had all the squares filled, out in that one, right?

134:26:08 Cernan: You fooled me.

134:26:09 Stafford (onboard): OK. Coming up 20 - 21:40.

134:26:23 Young (onboard): OK. What time is the...

134:26:28 Stafford (onboard): 27:40 at the ACQ time and 29:12 [garble].

134:26:34 Young (onboard): OK. There's [garble].

134:26:41 Cernan (onboard): Oh, yes.

134:26:45 Stafford (onboard): Oh, yes. Here's Bruce. Old Bruce is out there, babe. See Bruce?

134:26:50 Cernan (onboard): What's up in the air up there, babe? Is that a star?

134:26:53 Stafford (onboard): I guess so. It's out of plane, whatever it is; it can't hurt us.

134:26:56 Young (onboard): It's going to be a low sun angle. That'll be pretty good.

134:27:04 Stafford (onboard): There it goes into the terminator.

Air-to-ground audio

134:27:09 Engle: OK, Apollo 10. This is Houston. Let's see, Gene, I've got a short map update and a photo update; however, did I copy before, that – You say you are out of film, or you're about out of film?

134:27:25 Stafford: Stand by, Joe. We're in the middle of a landmark tracking. We'll call you. Over.

134:27:28 Engle: Sorry. Standing by.

134:27:34 Cernan (onboard): God dang! [Garble] out here, isn't it?

134:21:39 Stafford (onboard): Can you see him. John?

134:21:40 Young (onboard): Well, we're coming right into the terminator, anyway.

134:27:43 Stafford (onboard): Yes. I got Bruce and this other one - Linne [mistaken, as Linne is in Mare Serenitatis] - or something like that. You got the rille up there. I got your landmark. OK, you should be seeing - acquiring him now.

134:28:11 Engle: OK, 10. This is Houston...

134:28:12 Young (onboard): Can you pitch up some. Tom?

134:28:13 Engle: ...We observed on your last mark there, that you got four marks and the last one was just past the nadir. It looks like if you increase your pitch rate just a little bit, you can probably get five Marks without any problem.

134:28:27 Stafford: Roger. Pitch up.

134:28:32 Young (onboard): [Garble] Bruce.

134:29:07 Young (onboard): OK. T.P, start a pitch-down.

134:29:11 Stafford (onboard): Pitching down, babe. Is that enough? You can mark him any time now, babe.

[The crew is now marking on landmark 150. Due to the low Sun angle illumination of this area, Young had difficulty identifying the correct target. After the flight, the actual site that he had marked was located, and is shown as 150/10.]

Landmark 150 and 150/10

Landmark 150 and 150/10 in Sinus Medii near landing site 3.

(Click on the above image for a larger version.)

134:29:20 Young (onboard): OK.

134:29:23 Stafford (onboard): Let me know when...

134:29:24 Young (onboard): I think it's him.

134:29:27 Stafford (onboard): Did you get one?

134:29:51 Stafford (onboard): OK. Got him?

134:29:59 Young (onboard): Not yet.

134:30:01 Stafford (onboard): Mark.

134:30:04 Stafford (onboard): 5 seconds gone.

134:30:06 Young (onboard): That wasn't him.

134:30:01 Stafford (onboard): Want to kill it or keep going? Just keep on...

134:30:09 Young (onboard): Keep going.

134:30:11 Stafford (onboard): 10. 15. 20 - Pitch down some more?

134:30:30 Young (onboard): Yes.

134:30:34 Cernan (onboard): That's your old friend Mars up there.

134:30:36 Stafford (onboard): 10. 15. 20. 25. 30. 5. 10. 15. 20. 25. OK - 5, 10. 15. 20, 25. OK. Is that it, five - marks?

134:31:52 Young (onboard): Isn't that it?

134:31:53 Stafford (onboard): Yes. OK.

134:32:09 Young: Houston, this is 10. Over.

134:32:12 Engle: Roger, 10. Go ahead.

134:32:17 Young: Roger. That first Mark of that group was not on what I think is site 150. This low Sun angle - You got so darn many craters out there - The grouping don't stand out like they do with a high Sun angle, and I’m not even sure that I marked on 150, although it was one of three craters in there, with pretty high contrast.

134:32:43 Stafford (onboard): There's that thing again, out in front of us.

134:32:44 Cernan (onboard): No, that's Mars; I just looked at it.

134:32:46 Stafford (onboard): Look down on the ground, babe.

134:32:50 Young: The first Mark definitely was not on the – on the site - on what I thought was 150, but the last four were.

134:33:00 Engle: OK. We copy that, John. Thank you.

134:33:06 Stafford: Joe, I've got this object out in front of me again. I'm sure that you can say orbital mechanics - it must be a big hunk of Mylar out there in reflected sunlight. It's going into its own terminator now, and it's held about the same. It's pitched down at a local vertical of about, I'd estimate - I'm coming up to it now - 330 degrees. It's holding out there at 330.

134:33:29 Cernan (onboard): How can it be in the sunlight when we're into darkness already?

134:33:33 Engle: OK. Sure understand. And you think that's a...

134:33:36 Cernan: Joe, do y'all have the...

134:33:37 Engle: You think that's a hunk of Mylar, you say, Tom?

134:33:40 Cernan: You have the data, Joe?

134:33:41 Stafford: Yes, to be - to be that - that low down with the lowest and still keep about the relative position, it's got to be, Joe. Over.

134:33:44 Cernan (onboard): It would have to be, to be in sunlight.

134:33:51 Engle: OK. You can't get the monocular on that, can you?

134:33:57 Cernan: Joe, I'm looking at it now, and to be in sunlight where it is, it has to be awfully close to us and I got the monocular on it and I think it's a piece of Mylar, too.

134:34:08 Engle: OK. Mighty fine. Thank you.

134:34:09 Cernan: It will probably go into darkness about - I'll give you a hack. It ought to go into darkness about the same time we do, if we can tell here, and I’m pretty sure it's not too far away.

134:34:19 Stafford (onboard): That tail is still up in sunlight.

134:34:21 Engle: OK. We understand. And understand you're ready for this map update PAD?

134:34:28 Cernan: No, let me watch this thing first. Then I’ll get it.

134:34:31 Engle: OK. Give me a call when you're ready.

134:34:36 Cernan (onboard): Tom. when you fire the thrusters, it sort of lights it up.

134:34:39 Cernan: Houston, do you have the data from that landmark? Over.

134:34:43 Stafford (onboard): It does, doesn't it?

134:34:45 Cernan (onboard): Does what?

134:34:46 Stafford (onboard): Son of a gun; it does.

134:34:47 Engle: Roger. We got it.

134:34:48 Cernan (onboard): It's got to be pretty close. If it was the LM, it couldn't be - it couldn't be that far away. You know, it would still be in sunlight if it were that low.

134:34:57 Stafford (onboard): No. It's [garble] out there.

134:34:57 Engle: 10, this is Houston. Jack says that it looked like your last four marks were spaced very nicely over the target.

134:35:08 Young: Yes. Whatever it was.

134:35:11 Stafford: Roger.

134:35:12 Young: I think that was Site 150, but boy, there are a lot of shadows out in that place right now, and I wasn't 100 percent sure that that was Site 150 crater.

134:35:24 Engle: OK. We copy.

134:35:33 Young: But it was darn close if it wasn't.

134:35:35 Engle: OK.

134:35:42 Stafford (onboard): No, [garble].

134:35:44 Cernan (onboard): No. He's farther away than that but...

134:35:46 Stafford (onboard): That's got to be Mylar. Right? That couldn't be...

134:35:48 Cernan (onboard): couldn't be Snoopy down there; because, you know, if he were down there, he would be in darkness.

134:35:55 Stafford (onboard): Well, also, his orbital mechanics at that relative rate out there - huh - uh.

134:36:05 Young (onboard): He'd be moving way out.

134:36:10 Cernan (onboard): The obvious thing to me is that he would be in darkness, right now, and he's not. So he's just...

134:36:18 Stafford (onboard): Right about our same level - -

134:36:20 Young: Houston, both those - Both those last sites were done with a telescope. I couldn't pick either one of them up in the sextant. The first one was almost dead. It was washed out in the sextant due to sunshine, and the second one, I just didn't - With all the shadows, I couldn't see anything.

134:36:42 Engle: Roger. Copy, John.

134:36:44 Young: It wasn't defined in the sextant.

134:36:51 Cernan: Joe, I'm ready for your update.

134:36:54 Engle: OK. This is for Rev-31. LOS is 135:09:24, 135:20:09, 135:55:30. And that's all; I'll stand by for your readback.

134:37:22 Cernan: OK. They're all 135. They go 09:24, 20:09, 55:30.

[Rev-31 map update details are LOS, 135:09:24; crossing 150°W, 135:20:09; AOS, 135:55:30.]

134:37:29 Engle: Roger. That's correct, and on this photo update, again Gene-o, just - Did you figure you guys are out of film up there? There's no sense sending it up if you're all out.

134:37:39 Cernan: No, we got a little bit left; we've been saving for this - Give us the update.

134:37:45 Engle: OK. Coming up. Descent strip and Site 3: 135:59:24, 136:01:01, 136:18:52. Your ORDEAL angles are roll 180, pitch 282, yaw 000. At T-1, yaw right 20 degrees. At T-2, yaw left 20 degrees. That concludes, and standing by for the readback.

134:37:48 Cernan: OK. 135:59:24, 136:01:01, 136:18:52. Orb rate is in roll, 180; pitch, 282; yaw, 000. At T-1, yaw right 20 degrees, and at T-2, yaw left 20 degrees.

[Description of the photo PAD:
The strip photography, beginning at 90° East T-0, 135:59:24, and continuing to the terminator. The spacecraft is yawed 20° off the vertical at 85°E T-1, 136:01:01, to center Censorinus (32° East) and its approach path in the strip and maneuvered back to vertical at 30° East T-2, 136:18:52, to center on landing site 3 (1.4°W) in Sinus Medii and its approach path in the photo strip.]

Apollo 11 training chart of appropach to LS3

Apollo 11 training chart of the area of final approach to landing site 3, which Apollo 10 is photographing.

(Click on above image for a larger version.)

134:39:04 Young (onboard): OK. Can you get me some stars?

134:39:06 Stafford (onboard): You don't need to do alignment now, babe...

134:39:07 Engle: OK. Read back's correct, Gene-o.

134:39:08 Stafford (onboard): ...unless you want to. You don't need to do any more alignments until that last big one, babe.

134:39:10 Cernan (onboard): Doesn't call for any alignment.

134:39:12 Young (onboard): Doesn't call for any? Oh, shit; what am I going to do? Sit here and watch the caution and warning lights?

134:39:19 Stafford (onboard): You want to give them a TV test? (Laughter)

134:39:22 Cernan: And are you going to update us the omnis or you want us to get High Gain?

134:39:26 Stafford (onboard): We're using B and D for that ullage. That should be not using any out of A and C.

134:39:28 Engle: We'd like to have High Gain, Gene-o. We'd like to look at some of the data.

134:39:31 Young (onboard): You got it set up so we can do that?

134:39:33 Stafford (onboard): No.

134:39:38 Cernan: Verb 64. Stand by.

134:40:44 Stafford (onboard): Very good [garble].

134:40:56 Cernan: Houston, are you reading us High Gain?

134:41:00 Engle: OK. We got it. Thank you, Gene-o. And if you'll give us P00 and Accept now.

134:41:03 Young (onboard): Oh - what's...

134:41:07 Stafford (onboard): What's what?

134:41:08 Cernan (onboard): [Garble] longitude at [garble].

134:41:11 Young (onboard): [Garble] longitude?

134:41:13 Stafford (onboard): It's about zero.

134:41:17 Cernan (onboard): Latitude and longitude - site 3.

134:41:22 Stafford: OK, Joe. You’re CMC and Accept. You got it.

134:41:22 Young (onboard): 283 minus 714.

134:41:25 Engle: OK. Thank you, Tom.

[Comm break.]

134:46:45 Cernan: Houston, how's your High Gain lock now?

134:46:56 Engle: OK 10. It looks like we're on Wide right now.

134:47:04 Cernan: Negative. [Garble]. We're [garble].

134:47:42 Engle: 10, this is Houston. We're not able to read your transmission here. You're coming through a little broken up and it looks like - From the data, it looks like you're coming in on the scan limit.

134:47:57 Cernan: OK. Now I think you got it. Go ahead.

134:48:00 Engle: Roger. You're booming in loud and clear now. And we got good data now, Gene-o.

134:48:04 Cernan: OK.

134:48:54 Engle: Apollo 10, this is Houston. The computer is yours. You can go back to Block now.

134:49:01 Stafford: Roger. We're in Block.

Air-to-ground audio

134:52:08 Stafford: Hello, Houston. Apollo 10.

134:52:11 Engle: Roger. Go ahead, 10.

134:52:15 Stafford: OK. We're loading the DAP to set up for TEI. We've got the two-jet ullage in, set up for B and D and plus-X translation in register 1, if you're reading our DSKY. OK. Now for register 2, just to reaffirm here, we're going to use B and D for roll, too. Over.

134:52:36 Engle: Roger. That's affirmative.

134:52:43 Stafford: OK. You know, we want to activate quad D, though. Is there any quad we want to have fail there in register 2 other than use BD in the first digit? Over.

134:53:06 Engle: OK, Tom. We do not want to fail any quads. We want a zero and four ones in there.

134:53:15 Stafford: OK. That's what we thought.

134:55:13 Cernan: Hello, Houston. This is 10.

134:55:14 Engle: Roger. Go ahead, 10.

134:55:18 Cernan: OK. It looks like our condenser exhaust temperature, once we come into nighttime, is now starting to cycle again. It's starting slowly. You can watch it from where you are, I guess.

134:55:34 Engle: OK. We'll monitor it down here, Gene. Thanks for alerting us. And also, Tom, just to remind you, we want you to Enable all the Auto RCS for your burn.

134:55:49 Stafford: Roger. You want all Auto RCS. That includes AC for roll, too? Over.

134:55:53 Engle: That’s affirmative.

134:55:57 Stafford: Say again.

134:55:59 Engle: That's affirmative.

134:56:03 Stafford: OK.

134:58:53 Engle: Apollo 10, Houston.

134:58:58 Stafford: Go ahead.

134:59:00 Engle: OK. On your fuel cell there, we're monitoring this power output on 2 and 3, and the load sharing appears to be normal, although we are monitoring this change in temperature on the condenser exhaust. We're showing about - Oh, it's grown to about an 8- or 9-degree spread, now. However, it doesn't look like we could recommend any kind of changes right now. We'll keep watching it, though.

134:59:28 Stafford: OK, Joe. Thank you.

Flight Plan

[Comm break.]

135:07:48 Cernan: Houston, this is 10. What's your temperature limits at that exhaust temperature's oscillating through now?

135:08:17 Cernan: Hello, Houston. 10.

135:08:19 Engle: Roger, 10. I was just getting those numbers, Gene-o. The lower limit is 149.5, and the upper limit is 177 [deg F].

135:08:30 Cernan: You mean it's going from 149.5 to 177?

135:08:34 Engle: I'm sorry; I misunderstood you. What we're reading is from about a 154.2 or so up to 167. The limits where you're liable to get a light is 149.5 to 177. Over.

135:08:50 Cernan: OK. Thank you, Joe. You're reading about the same thing I am, I guess. I expect the light here about a minute and a half after we lose you.

135:08:59 Engle: OK. I'll tell you, Gene, we've been monitoring the cycles here, the oscillation, and it looks like it opened up to about a 15-degree – 14- or 13- or 14-degree spread. And it appears to be holding that pretty steadily, and it's going up and down between about the same limits. Is that about what it looks like to you?

PAO audio

135:10:29 Engle: Apollo 10, Houston.

135:11:40 PAO: This is Apollo Control. We've had Loss Of Signal now. We'll be reacquiring Apollo 10 in about 43 minutes. The spacecraft at that time will be in its 31st revolution. During that revolution, we'll be passing up the information that the crew will need for their Trans-Earth Injection maneuver. That burn is scheduled to occur at 137 hours, 36 minutes, 28 seconds and, of course, will take place behind the Moon while we're out of contact with Apollo 10. The burn duration [means change of velocity] is currently planned at 3,631 feet per second [1,107 m/s] with a burn duration of 2 minutes, 41 seconds. During that last pass on rev-30, as we reacquired the spacecraft, Gene Cernan came on to advise that he had noticed a temperature cycling in fuel cell number 2 in the condenser exhaust temperature. This was cycling, he said, between 155 degrees and 173 degrees [Fahrenheit, 68°C and 78°C]. Later he reported that the cycling had reduced, that the temperature range had stabilized and the fuel cell temperature had become stable and as the spacecraft moved into darkness again, near the end of the acquisition period, Cernan reported again that the temperature was beginning to fluctuate. We were also able to monitor that temperature fluctuation here on the ground. The temperature range was cycling on the order of 10 or 15 degrees, ranging from between 153 to around 165 or 68. There's no concern about the temperature on the low side. The temperature ranges on the high side can get up to around 200 degrees before there is any concern with that particular temperature. We'll continue to observe that parameter in the fuel cell when the spacecraft comes back around on the 31st revolution. At this time, it does not appear to be a problem. The EECOM, the electrical and communications engineer reports that the fuel cell appears to be functioning normally in all other aspects and is sharing the load as it should and that its power output is absolutely nominal. At 135 hours, 15 minutes; this is Apollo Control, Houston.

[No onboard DSE recording is available following LOS.]

[135:13:-- Begin lunar Rev-31]

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