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Mid course correction and TV transmission Journal Home Page Revision and TV in the blind

Apollo 10

Day 2 part 9: Housekeeping, sleep and TV.

Corrected Transcript and Commentary Copyright © 2009 by David Woods, Robin Wheeler and Ian Roberts. All rights reserved.
Last updated: 2017-02-10

Flight Plan Page 3-21

030:00:26 Stafford: Houston, Apollo 10.

030:00:30 Duke: Go ahead, Apollo 10.

030:00:33 Stafford: Okay. At 30 hours, we have a LM/CM Delta-P for you as per Flight Plan. It is now reading 1.05 psi.

[The pressure differential between the CM and LM has increased slightly since the last reading of 0.9 psi at 022:16:42. Since the the LM has not been repressurised since the initial pressurisation shortly after the Transposition and Docking, the change indicates the rate at which the lander is losing cabin atmosphere. This rate of increase is well within the acceptable figure and indicates that the LM pressure integrity is very good, and that the seal in both the CM hatch and the LM hatches are sound.]
030:00:42 Duke: Roger. Copy, Tom.

030:00:46 Stafford: Roger.

030:00:47 Young: This thing's really tight over there.

030:00:49 Duke: Roger. We agree.

030:01:02 Duke: And, 10, this is Houston. There is no need to reinitiate the CM purge now.

[As the Delta-P readout has confirmed the pressure integrity of hatches in the LM, MCC-H has decided that it would not be necessary to reinitiate the CM purge, which would have assisted in maintaining the required pressure in both the CM and LM.]
030:01:12 Young: Roger.
[Very long comm break.]
PAO: This is Apollo Control. During that last transmission you heard the crew remark that the Delta P - the difference in pressure between the Command Module and the Lunar Module now reads 1.05 pounds per square inch, What that means is that the Lunar Module, which following Earth Orbit Insertion, had a cabin pressure equal to that of the Command Module but has not been repressurized, in the meantime has lost a very small amount of its cabin atmosphere. This in turn is an indication of a very tight cabin. At the present time, Apollo 10 is at a distance of 120,271 nautical miles [222,741 km] from Earth and travelling at a speed of 4,775 feet per second [1,456 metres per second], The change-of-shift Press Conference is scheduled to begin shortly and during the Press Conference we will record any further conversation with the spacecraft and play that back following the Press Conference. This is Apollo Control at 30 hours, 5 minutes.

030:27:11 Duke: Hello, Apollo 10. Houston.

030:27:16 Young: Go ahead. Over.

030:27:17 Duke: Roger. We'll have a station handover in about 3 minutes and 45 seconds. We're going back to Goldstone, it looks like.

030:27:25 Young: Roger.

[Long comm break.]
030:31:38 Stafford: Hello, Houston, Apollo 10. How do you read now?

030:31:53 Duke: 10, Houston. Go ahead.

030:31:57 Stafford: Roger. Just wanted to check with you on the new Comm station. One thing we're doing here during all this spare time, we're getting out our lunar operation cards and charts and going through the whole thing, just having a skull session. And we'll he doing this for about the next 2 days, just reviewing the stuff. Just like going through a simulation.

030:32:15 Duke: Roger, Apollo 10. We copy. We...

030:32:23 Stafford: We might have a few questions coming down.

030:32:27 Duke: Roger. We'll be standing by with all the guys, Tom, and we finally located our backup set, and we'll be doing the same thing.

030:32:38 Stafford: Okay. Real fine, Charlie.

030:32:42 Duke: Any other requests you guys got? Looks like to us this PTC is beginning to work. We see it going off in pitch and yaw, but it is not coupling and going to one - spiraling out to one edge of the deadband. It's just going back and forth between pitch and yaw, well within the deadband.

[The new procedure for initating the PTC is proving to be satisfactory. The crews concerns that the roll rate could couple with the yaw and pitch rates are not being born out.]
030:33:01 Young: Yes. It looks like it's going to work.

030:33:03 Duke: Well, we hope so after all that.

030:33:04 Stafford: We apologize.

030:33:05 Duke: Well, we apologize to you guys for not being straight on the procedure.

030:33:11 Young: Well, I still - I don't know why the other one wouldn't have worked either.

030:33:17 Duke: We. Can't answer it either, John, really. It's just one of these black magic ones, I guess.

030:33:29 Duke: We've had a shift change down here. Too bad you guys have to work 24 hours a day up there. Well - We got the Maroon Team, it is, is on now.

030:33:45 Stafford: Okay, Charlie. Take it easy.

030:33:46 Duke: Roger.

030:33:48 Young: We'll see you tomorrow.

030:33:49 Duke: We'll see you tomorrow.

030:33:51 Stafford: Okay. One thing about working 24 hours a day, we’ve got a beautiful view up here.

030:33:54 Duke: Yes. It's well worth it, Tom. We're real envious.

030:34:01 Stafford: Yes. One thing of interest to note: you know the total clouds we described to you on TV?

030:34:06 Duke: Yes.

030:34:07 Stafford: From our angle now, it looks like the whole northern quarter of the whole globe is completely socked in there; and, again, the United States is what really stands out and part of Mexico. We can see the Gulf Coast from here real well, right through the hatch window.

030:34:21 Duke: Roger. It's still - Everybody who just came in from outside said it's still clear, so that's a good description.

030:34:29 Stafford: We'll see you tomorrow, Charlie.

030:34:30 Duke: Roger. Good night.

[Very long comm break.]
030:55:43 Cernan: Hello, Houston. This is Apollo 10.

030:55:47 McCandless: Apollo 10, this is Houston. Over.

030:55:52 Cernan: Hey, Bruce. We just want you to eye overnight on the SPS oxidizer - ullage pressure. I've seen it - after yesterday's burn - drop maybe about 5 psi, and after today's burn, it appeared like it's slowly dropping. It may be a temperature effect, but I'd like you to keep an eye on it overnight.

[The SPS pressurization subsystem consists of two helium tanks, two helium pressurizing valves, two dual pressure regulator assemblies, two dual check valve assemblies, two pressure relief valves, and two heat exchangers. The critical components are redundant to increase reliability. The helium provided pressurisation of both the fuel and oxidiser tanks. This pressurisation provided the ullage pressure to the propellants to ensure the correct flow to the engine injector plate.]

The SPS propellant storage and pressurisation system locations.


SPS fuel tank during installation into SM-107 (Apollo 11) at North American.

(Click on photo for larger image.)

030:56:18 McCandless: Roger. We'll keep a watch on it.

030:56:22 Cernan: Okay.

030:57:13 McCandless: Apollo 10, this is Houston. Over.

030:57:19 Cernan: Go ahead, Houston.

030:57:21 McCandless: Roger. This oxidizer tank ullage pressure decrease was also noticed on 8. We saw some of it last night. The explanation is that the oxidizer is absorbing the helium that is present in the tank, causing the pressure to decrease. When it becomes saturated with helium, then things will remain static in this respect for the rest of the mission. Over.

030:57:51 Stafford: Fantastic there, Bruce.

030:57:55 Cernan: Okay. I'm just glad to hear those kind of answers, because I've been looking here at it, too, for a couple of days.

030:58:01 McCandless: Roger. We will keep an eye on it, though, for you.

030:58:05 Cernan: Okay. That makes me feel a little bit warmer.

030:58:09 McCandless: Roger.

030:58:43 McCandless: Apollo 10, this is Houston. We've been having some difficulties with the Data Storage Equipment under ground command here, so we've started the tape. We'd like to record a few minutes worth of random data, and then try dumping it back down to verify our system here.

[The Data Storage Equipment (DSE) onboard the CM recorded both crew audio and data during periods when the air-to-ground communications were not possible, i.e. whilst between the coverage of the ground station when in Earth orbit, or during the spacecrafts passage behind the Moon. The DSE could be operated manually onboard or by remote commands from MCC-H.]

DSE external DSE internal

(Click on photo for larger image.)

030:59:06 Cernan: Okay. I have the gray up here so I guess it's on okay, Bruce.

030:59:10 McCandless: Roger.

[Very long comm break.]
PAO: This is Apollo Control at 31 hours, 5 minutes, Apollo 10 is at a distance of 123,024 nautical miles [227,839 km] from Earth. Current velocity is 4,690 feet per second [1,430 m/s]. During the Press Conference we have accumulated several minutes of tape conversation with the crew. Included in that conversation was a report on the Passive Thermal Control rotation mode that the spacecraft has been put into and an assessment that at first appearances it seemed to be working quite well. We'll play back the tape for you and then stand by for any further conversation.

PAO: All continues to be quiet from the spacecraft. At this time the crew is scheduled to be having their evening meal. As you've heard we've had a change of Capsule Communicators here in Mission Control. Astronaut Bruce McCandless has relieved astronaut Charlie Duke as the spacecraft communicator. At 31 hours, 14 minutes into the flight of Apollo 10, this is Mission Control, Houston.

031:13:36 Stafford (onboard): Well, that's the swing arm right here.

031:13:38 Young (onboard): Um huh.

031:13:39 Cernan (onboard): Huh?

031:13:40 Stafford (onboard): That's the swing arm. You twirl with this, see?

031:13:59 Stafford (onboard): You want to shoot the Earth out of your window, Gene-o?

031:14:02 Cernan (onboard): What's the setting? You want me to get that one?

031:14:04 Stafford (onboard): f:ll at 250. If you want to, it's right there, babe. [Garble].

031:14:09 Cernan (onboard): Yes.

031:15:10 Stafford (onboard): What I've been doing is trying to - halfway in between the [garble]...

031:15:12 Young (onboard): God, look at that!

031:15:14 Stafford (onboard): [Garble].

031:15:15 Young (onboard): That is absolutely ridiculous!

031:15:17 Stafford (onboard): Where - where's the water, old buddy?

031:15:21 Young (onboard): That's it!

031:15:28 Stafford (onboard): We'll shoot most of them on the Moon, babe. A couple of those'd be real good to correlate with what the other stuff is.

031:15:41 Cernan (onboard): Supposed to let the air out. Just swing it around - It no going down - isn't the water going down?

031:15:43 Stafford (onboard): Uh-uh - Gosh.

031:15:56 Cernan (onboard): Close the valve. You got to close the valve.

031:15:59 Young (onboard): How?

031:16:00 Cernan (onboard): I don't know - to the close - whatever closed is.

031:16:14 Stafford (onboard): [Garble] like if they had been packed real [garble] to start with, John. See?

031:16:19 Young (onboard): Oh, shit! What they did, they made it a two - Ain't this smart! Ain't that a smart freaking sack. Now you tell me how you're going to get the goddam - Oh, I got it, you wasn't supposed to do that.

031:16:38 Cernan (onboard): Yes, you were.

031:16:39 Stafford (onboard): Yes, you are...

031:16:40 Cernan (onboard): Yes, you are; yes, you are...

031:16:41 Stafford (onboard): [Garble]. Now, Jose. We're all set to go.

031:16:42 Cernan (onboard): But put more water in it, why don't you, if you're going to swing it?

031:16:44 Stafford (onboard): See.

031:16:45 Young (onboard): Oh, you don't - Ain't - How'd you do it?

031:16:48 Stafford (onboard): Yes, it is. Now - now look, old - You take this, and give it the twist. Start giving it the rpm. All it does, it looks like to me, is mixes up the water in there. (Laughter) That freaker ever gets loose [garble]. Now what do you got?

031:17:09 Young (onboard): We have to open the valve and let the air out.

031:17:11 Stafford (onboard): Oh, open the valve, and let the air out.

031:17:13 Young (onboard): I got water - (laughter) - I got air down in the bottom of my water.

031:17:15 Stafford (onboard): (Laughter)

031:20:38 Young (onboard): How do we get the water out to drink it?

031:21:35 Young (onboard): How do we get the water out to drink it, you guys?

031:21:39 Stafford (onboard): Did it come out through the air valve?

031:21:48 Young (onboard): No. That's another little discrepancy (laughter). It didn't say how to (laughter) get the goddam stuff out of it.

031:22:31 Stafford (onboard): You can tell we're up above the Earth, Gene-o. Draw a line to the north pole and the south pole. We're up above the equatorial plane.

031:22:41 Cernan (onboard): Yes. You sure can tell that.

031:22:53 Stafford (onboard): Man, that TLI was quite a ride. Never forget that son of a bitch. We still recording?

031:23:05 Cernan (onboard): Yes.

031:23:39 Young (onboard): Now the theory, I think, is you get the water in there with them bubbles in it like that, swirl it around like that, and you end up with the water all down in the bottom end with the bubbles in it. (Laughter) That makes my whole day! Did you see that? That son of a gun! It ain't done nothing but carry the bubbles down the bot - bottom.

031:24:22 Stafford (onboard): (Laughter) Look, you're slinging water all...

031:24:40 Young (onboard): [Garble]...

031:24:41 Cernan (onboard): Well, there - there's the big...

031:24:44 Stafford (onboard): The big bubble's at the bottom (laughter).

031:24:48 Young (onboard): Well, that's water.

031:24:50 Stafford (onboard): Where's the air?

031:24:55 Young (onboard): There's the air bubble (laughter).

031:24:56 Cernan (onboard): That's right (laughter). That is a big bubble.

031:25:02 Stafford (onboard): Is that the water or the air? That is the biggest - How come the biggest air bubble goes to the bottom?

031:25:14 Young (onboard): I don't know, it's the scientifical way to just - do it.

031:25:18 Stafford (onboard): (Laughter) We Just - theoretically, it – squeeze it up like this.

031:25:25 Young (onboard): What that means, instead of drinking water aerated, you drink it with the bubbles in it (laughter).

031:25:31 Stafford (onboard): And the bubbles won't mix. Oops.

031:25:40 Young (onboard): Watch out! Oh.

031:25:42 Stafford (onboard): Um-um. I'm sorry. Didn't know the valve was opened.

031:25:49 Young (onboard): Yes, I'm sorry. I left it op - That's how you do it.

031:25:54 Stafford (onboard): Let me shut this valve. Is that shut there?

031:25:59 Young (onboard): Yes.

031:26:03 Stafford (onboard): But there's still air there, John.

031:26:05 Young (onboard): I know it.

031:26:06 Stafford (onboard): I can't get the - can't get the air out the bottom.

031:26:08 Young (onboard): I know it.

031:26:17 Stafford (onboard): I'm going to see if I can [garble].

031:26:37 Stafford (onboard): Now, we got all the air in the top, right?

031:26:39 Young (onboard): Yes, that's right...

031:26:40 Stafford (onboard): We got the whole mass in the top.

031:26:42 Young (onboard): Yes. Now, let me - let me twirl it (laughter). That can't [garble] go to the bottom, the very bottom!

031:27:12 Young (onboard): There's something we don't understand about it.

031:27:18 Young (onboard): Ain't there. Maybe.

031:27:42 Young (onboard): What do you think, T.P.? This was supposed to be carried with it, and what we did was put this in the bag, as I understood it, and twirled it around. That how you understood it?

031:27:51 Stafford (onboard): Yes. And the heavy stuff would run to the bottom, and the air would be at the top, and we could just kind of squeeze it up and the air would go out the top.

031:28:11 Young (onboard): That is absolutely too much.

031:28:18 Stafford (onboard): I'll bet in one g it won't work.

031:28:20 Young (onboard): (Laughter) [Garble] shit.

031:28:31 Cernan (onboard): What - Doesn't the air come up to the top, or what?

031:28:34 Stafford (onboard): No. Now we got the air at the bottom, you see that big air bubble? It's at the bottom. There it is. See, you've got to get that there out of there. You start working, there's another air bubble -

031:28:48 Cernan (onboard): Apparently, you really got to - got to twirl that thing to really put some g forces on it.

031:28:53 Stafford (onboard): I think there's a meniscus effect in there, or something...

031:28:57 Cernan (onboard): You've got a venturi in there, too.

031:29:00 Young (onboard): Yes, some kind of maturate - mat - venturi...

031:29:03 Stafford (onboard): I guess you're - You really need to fill the bag up all the way with water, huh?

031:29:07 Young (onboard): Yes.

031:29:10 Stafford (onboard): What I would guess is that you'd fill it up more than [garble] let me - project for today.

031:29:59 Stafford (onboard): Do you think they tested this in one g?

031:30:02 Young (onboard): I don't know; but you know, it could be that nobody ever explained to us? how it is supposed to work, so we don't know. Maybe we're not doing it right.

031:30:12 Stafford (onboard): Is it in the sys - Look at all that air in there; I can't believe it: Look at that!

031:30:18 Cernan (onboard): That thing right there was 7 inches longer than it is now, too. Where the hell would you swing 7 more inches?

031:30:53 Stafford (onboard): You know one thing we have to comment on is this drink gun is a remarkable improvement over the old squirt, you know, half-ounce squirt? [Garble] don't...

031:31:24 Young (onboard): Oh, shit!

031:31:26 Stafford (onboard): Put's all the air in the one big bubble. But you can't get the big bubble out. What are we going to do with all this water we got? (Laughter) It does centrifuge air the water into one bubble.

031:31:59 Young (onboard): Well, this being hydrogen, we could always put a match in it or something.

031:32:06 Cernan (onboard): Yes (laughter).

031:32:26 Stafford (onboard): I guess if you filled it all the way up - you have to fill it all the way up, John.

031:32:30 Young (onboard): Yes.

031:32:31 Stafford (onboard): Why don't I try it?

031:32:33 Young (onboard): Well, I’d...

031:32:35 Stafford (onboard): You think it would waste too much water?

031:32:38 Young (onboard): I don't know, Tom.

031:32:40 Stafford (onboard): Huh?

031:32:41 Young (onboard): We ought to learn how to use it before we have to. But I don't think filling it all the way - I think filling up the top compartment was what they had in mind. And then - then swirling it around until ... it went down to the bottom compartment.

031:32:57 Young (onboard): Umph. Umph. Umph. Umph.

031:33:41 Stafford (onboard): Okay, that's about filled up now.

031:34:09 Stafford (onboard): That water tastes good now, you know it?

031:34:11 Young (onboard): Yes.

031:34:12 Stafford (onboard): Nice and cold. Tastes great that way: Shoot: I got an even bigger bubble down below, John. I got air above [garble] (laughter). Did anybody really try this with aerated water?

031:34:45 Young (onboard): Well, you want to get Houston to explain it to us?

031:34:51 Cernan (onboard): (Coughing)

031:34:57 Stafford (onboard): No, they'll just get in a big flap over it.

031:35:08 Stafford (onboard): Well, I can't get that air bubble out of the – I defy anybody to got that air bubble out of the bottom into the top.

031:35:30 Young (onboard): (Laughter) That's right (laughter).

031:35:32 Stafford (onboard): Hey, that water goes out of the top (laughter) [garble]...

031:35:37 Cernan (onboard): That's what you're supposed to do.

PAO: This is Apollo Control at 31 hours, 37 minutes. Our spacecraft now at a distance of 124,441 nautical miles [230,463 km] from Earth and the velocity is 4,647 feet per second [1,417 metres per second]. CapCom Bruce McCandless has just put in a call to the crew and we're in conversation with the spacecraft at this time. We'll pick that up for you at the beginning.

031:36:34 McCandless: Apollo 10, this is Houston. Over.

031:36:39 Young: Go ahead there, Houston.

031:36:44 Young: Go ahead, Houston.

031:36:46 McCandless: Roger, 10. If you're through with your meal, we've got some conversation for John regarding the P23 sightings. Over.

031:36:55 Young: Okay. Go ahead.

031:36:57 Young: [Garble] go...

031:36:58 McCandless: Okay. The noise in the data is about 8 to 12 arc-seconds, which is considered to be very good. The nominal noise on the sextant with zero errors is 10 arc-seconds, so it looks like you're doing things perfectly on the sightings. With respect to the Delta-H, we got two different values. The one from yesterday implied using a reference at 33 to 34 kilometers. The sightings from today implied Delta-H of 13 to 14 kilometers. We suspect that the background light during today's sightings was higher than yesterday. This would probably cause difficulty in sensing the upper threshold at the same place as yesterday. You tend to pick out a brighter and hence lower horizon locator. The problem is not serious. It shouldn't cause any concern, but we'd like some comments from you specifically if you can compare the lighting background for today's sightings with the background that you had yesterday. And, can you determine where this light, if it was brighter, came from? Over.

031:38:35 Young: Well, there was a distinct horizon yesterday and I was marking on the uppermost limit of where it looked like the - Actually, there was a pretty definite, defined limit that I was seeing there yesterday. And today I didn't see that. It just looked like there was no – It just looked like there was a - if there was such a band, it was too narrow for me to notice.

[Whilst performing the P23 navigation program, John Young was establishing the height of the visible Earth horizon. He was sighting the upper visible layer of the atmosphere.

John Young from the Technical Crew Debrief, June 1969 - "The first set of sightings was for calibrating the horizon to my eye (and the horizon I was siting on, according to the data, was 32 to 34 kilometers). This was a very hazy layer above the horizon that appeared to be the highest line above the horizon where I could see a useful attitude. It was definitely well above the cloudline. The star horizon sightings were no problem and had gone just as in training. During the second period of star navigation sighting after the sleep period, the horizon was much less definite. In face, it appeared to be almost nonexistent. Those sightings were no problem."

From the Apollo 10 Mission Report, August 1969 - "Based on these measurements, the onboard computer compensation for horizon altitude was updated from 24 to 34 kilometers."]

031:39:07 McCandless: Roger. You also made a comment about losing a star in the horizon. Can you elaborate on that?

031:39:14 Young: You know, sometimes the Auto tracking tracks both the star and the - It puts the optics down on the Earth. The Mark on the horizon, you bring it up to the horizon and Mark on it. Well, when it doesn't - puts it down on the Earth. It was so bright today that I couldn't see any of the stars. Every time it would be too bright to see the stars, so I didn’t really know how you would do under those kind of conditions. It would be difficult to do star landmark, I believe.

031:39:53 McCandless: Roger. We copy. Thank you.

[Comm break.]
031:39:58 Stafford (onboard): (Sigh) Maybe we need more water on it, John. (Sigh)

031:40:37 Stafford (onboard): Something is really bright out there.

031:40:48 Stafford (onboard): What do you want to do with this, fill it up some more?

031:40:55 Young (onboard): (Laughter) What are we going to do with a bag full of water and bubbles? We'd better tell the ground. This is a serious problem (laughter).

031:41:06 Stafford: Hello, Houston; Apollo 10.

031:41:08 Young (onboard): (Laughter)

031:41:09 McCandless: Apollo 10, this is Houston. Go ahead. Over.

031:41:14 Stafford: Roger. Bruce, could you make a check and see if it was tested on the ground, prior to flight, for this little handheld centrifuge to separate air from water? We have some strange phenomenon, that the bubbles go to the bottom of the bag.

031:41:32 McCandless: Roger. It may take us a few minutes to track down the party responsible for the testing on this, but we'll check it out.

031:41:41 Stafford (onboard): (Laughter) (Air-ground) Yes, I wish you would. It's utterly phenomenal!

031:41:44 Young (onboard): (Laughter) (Air-ground) What happens is that we - we start out with a bag full of water and bubbles - little bitty bubbles, and we end up with a bag full of water and great big bubbles (laughter). And there is no way to separate the bubbles from the water - that I can see.

031:42:02 McCandless: Did you try spinning it the other way?

031:42:05 Young (onboard): (Laughter)

031:42:07 Stafford: Beautiful. Yes – yes, we have. (onboard) There's some more in it.

031:42:12 McCandless: Roger. We'll look into it.

[Long comm break.]
031:42:20 Young (onboard): (Laughter) Ooh! You know, that bag probably represents - (laughter) - the combined efforts of CSD, ASPO, and crew - and North American. It probably cost the government 25,000 dollars, and it probably don't work.

031:42:41 Stafford (onboard): You really have to - It looks like you'd have to really fill the thing up all the way, ... just really pack it in; now see that big bubble's starting to ... at the top. Boy, if this thing gets busted, it's going to be a disaster.

031:42:53 Young (onboard): Would it ever! You'd be going around the cockpit licking up - Take it easy with it, babe; because if it does bust, it'll sure be bad.

031:43:06 Stafford (onboard): Yes. Oh, I don't want to put too much.

031:43:10 Young (onboard): Maybe we- we're supposed to let it sit after we whirl it.

031:43:31 Stafford (onboard): Okay, another centrifuge test.

031:50:13 McCandless: Apollo 10, this is Houston. Over.

031:50:19 Cernan: Go ahead.

031:50:20 McCandless: Roger, 10. At this time, we'd like you to select H2 tank 2 heaters to Off. We're doing this in order to avoid giving you a master caution and warning light during your sleep period, if at all possible. Over.

031:50:38 Cernan: H2 tank 2 heater is Off.

H2 Tank Heater

Click on above image for full panel diagram.

031:50:41 McCandless: Roger.
[Very long comm break.]
PAO: This is Apollo Control at 32 hours, 5 minutes. Capsule communicator Bruce McCandless, has just put a call to the crew and we're in conversation with them now.

Flight Plan Page 3-22

032:05:00 McCandless: Apollo 10, this is Houston. Over.

032:05:07 Cernan: Go ahead, Houston.

032:05:08 McCandless: Roger, 10. To facilitate our DSE dump, we'd like to try High Gain Antenna acquisition once without disturbing the PTC. If we can't do it, we'll wait until tomorrow. Your procedure for High Gain Antenna pointing to Verb 64 in the checklist starts out with a Verb 37 Enter. Do not do the Verb 37 Enter. Just start right out with the Verb 64 Enter so that we don't disturb the PTC. Over.

[Verb 37 is the AGC command to change the current program. MCC-H is advising the crew to bypass this step and go straight to Verb 64 which is used to request the S-band antenna routine (R05). The DSKY will display the required S-band pitch and yaw gimbal angles to point the S-band antenna at the center of the Earth from the spacecraft's current attitude. The crew would then manually set the S-band antenna to the required pointing angles.]


S-band pointing P2

Click on above image for full panel diagram.


032:05:52 Cernan: Roger. You want us to put the Verb 64 to DSKY. Is that right?

032:05:56 McCandless: Roger. And acquire with High Gain Antenna.

032:06:08 Cernan: Okay. And the theory is, they probably don't disturb the PTC.

032:06:16 McCandless: Roger.

032:07:31 Stafford: Houston, do you have High Gain now?

032:07:36 McCandless: Negative, 10. Not yet.

[Long comm break.]
032:13:40 Stafford: Houston, we have it now.

032:13:44 McCandless: Roger. We confirm High Gain Antenna acquisition. And, I got a few other notes for you prior to your sleep period. Are you ready to copy?

032:13:56 Stafford: Stand by.

032:14:08 Cernan: Go ahead, Bruce.

032:14:11 McCandless: Roger. We'll be using Omni antennas tonight during PTC, and this will be Omni Bravo. We'd like to request that in setting up your Comm modes for this evening you ensure that the S-band Normal Mode Voice switch is Off, and use Down Voice Backup if you need to contact us during the night. There will be a waste-water dump after GET of 45 hours tomorrow. We'll give you an exact time tomorrow. We show rotational hand controller number 2 direct power to be On. We'd like it turned Off. The general consumables analysis for this point in the mission is that you're in good shape. If you need any specific numbers, why, we can supply them. Your PTC mode looks good so far. In fact, the angular excursions in pitch and yaw which had built up to about 7 or 8 degrees a half-hour or so ago seemed to have damped down and decreased to on the order of 4½ or 5 degrees at the present time. We'd like you to report after you finish chlorinating the potable water tank. And, we’d remind you to leave the potable tank inlet valve Open. Over.

[During the crew sleep periods the Omni antennas Bravo or Delta were used. These are on diametrically opposite sides of the SM and are selected remotely by MCC-H as the spacecraft rotates during the PTC.

There are two rotational hand controllers in the CM. Each controller has two modes, Normal or Direct. In Normal the commands are routed via the Command Module Computer (CMC) to the RCS. In Direct the commands are routed directly to the RCS direct coils on the appropriate engine. MCC-H have asked the crew to turn the Direct power on RHC 2 to off. It had been in the On position for the initial damping of the spacecraft's attitude rates prior to the PTC being initiated.

Click on above image for full panel diagram.

The crew had queried the request from MCC-H prior to the first sleep period to close the potable water tank inlet valve. The crew were proven to be correct. For the second sleep period the advice is to return to the normal pre-planned procedure and leave the potable water tank inlet valve open.

From the Apollo 10 Mission Report - "The ampules of sodium hypochlorite and sodium dihydrogen phosphate were injected at the scheduled inflight chlorination time of 12 hours. Because of a procedural error after this first chlorination, the potable water tank valve was not opened to allow dispersion of the injected solutions into the tank. The result was that the concentrated chlorine buffer solution passed directly through the drinking water dispenser when the system was used the next morning, with associated unpalatability. All subsequent inflight chlorinations, with one exception, were accomplished normally and as scheduled."]

032:15:52 Cernan: Okay. I think we got the chlorination information, and we'll let you know. And if we use Omnis. I imagine it will be a Delta and Bravo like we normally have been doing. And, you want the S-band Normal Voice – Mode Voice switch Off and you want to go Down Voice Backup?

032:16:10 McCandless: Roger.

032:16:12 Cernan: And we will be waiting for a water dump after 45 hours tomorrow.

032:16:18 McCandless: Roger. That's affirmative. Over.

032:16:24 Cernan: Okay.

032:16:24 Cernan: And when you are through with the dump, you let me know and I will set up the Omnis.

032:16:35 McCandless: Roger. We will give you a call.

032:18:40 Cernan: Houston, this is 10.

032:18:44 McCandless: Go ahead, 10. Over.

032:18:48 Cernan: Bruce, are you going to want to knock off the battery charge before sleep time tonight?

[The battery referred to is one of the CM re-entry batteries.]
032:18:52 McCandless: That's affirmative.

032:18:57 Cernan: Okay. [Long pause.]

032:19:45 McCandless: Apollo 10, this is Houston. We have a state vector to uplink for you, if you give us Accept on Up Telemetry. Do not, I say again, do not Enter Verb 37. Over.

032:20:01 Young: You want Accept, huh? Okay. Here comes Accept.

032:20:07 McCandless: Roger.

032:20:08 Young: You are in Accept now. [Long pause.]

032:20:31 Young: Can you guys send a vector with that thing running like that?

032:20:33 McCandless: 10, this is Houston. Negative. You need to hit Proceed for us.

032:20:39 McCandless: Roger. Thank you. For your information, your trajectory is looking good. We'll have a lunar flyby PAD for you here shortly. You’re Go for flyby in the event of lost comm, Over.

032:20:54 Stafford: Sounds good.

032:20:55 Cernan: Thank you.

032:20:57 McCandless: You are welcome.

[Long comm break.]
032:25:52 McCandless: Apollo 10, this is Houston. We are through with the uplink. You can go back to Block on Up Telemetry and we’d like to continue charging batteries as long as it’s convenient prior to your turning in for the evening. Over.

032:26:09 Young: Okay. Roger.

[Comm break.]
032:28:52 Cernan: Houston, 10. Looks like we're about to break lock. You want us to go Omni?

032:28:54 McCandless: Roger. You can go back to Omni at this time.

032:29:01 Cernan: Okay.

PAO: This is Apollo Control. We appear to have a fair amount of noise on the communications circuit at this time. The crew should be shortly getting the spacecraft ready for their sleep period. They will be, among other things, chlorinating their drinking water supply, setting up the communications system for their sleeping period, and changing out one of the lithium hydroxide canisters that removes carbon dioxide from the spacecraft atmosphere. The sleep period, a 9-hour rest period, is scheduled to begin at 35 hours Ground Elapsed Time, or about another hour and a half from now. At the present time the spacecraft is 126,784 nautical miles [234,803 km] from Earth traveling at a speed of 4,576 feet - feet per second [1,395 metres per second]. This is Apollo Control at 32 hours. 30 minutes.

032:32:19 McCandless: Apollo 10, this is Houston. We would like you to confirm that you selected Omni – Omni antenna Bravo - on board, and we'11 take over the switching between Bravo and Delta from down here. Over.

032:32:50 Cernan: Hello, Houston. How do you read?

032:32:52 McCandless: Roger. We are reading you weak, with noise in the background. Over.

032:32:57 Cernan: Okay. In order to get you, I had to go to Omni Delta and it looks like we may be losing you. I'll go ahead to Omni Bravo and you can do the switching.

032:33:07 McCandless: Roger. Thank you.

032:33:30 McCandless: 10, Houston. Radio check. Over.

032:33:35 Cernan: Roger. Reading you loud and clear in Omni Bravo. How do you read?

032:33:40 McCandless: Roger. We are reading you the same.

032:33:42 Cernan: Okay. We are in Down Voice Backup.

032:33:44 McCandless: Okay. A little clarification on that. We meant that when you secured for the evening, if you should need to contact us at that time, you would select Down Voice Backup, not that you should stay in Down Voice Backup all night.

032:34:04 Cernan: Okay. We will just do it to Voice again, and if we need you at night time, we'll go to Down Voice Backup.

032:34:10 McCandless: Roger.

032:34:23 Cernan: Hello, Houston. We're in Normal Voice. How do you read?

032:34:28 McCandless: Roger. That is much clearer, and no noise in the background.

032:34:31 Cernan: Okay.

[Long comm break.]
032:48:38 McCandless: Apollo 10, this is Houston. I have your flyby PAD P30 maneuver, when you are ready to copy.

032:48:46 Cernan: Stand by one.

032:49:15 Cernan: Go ahead, Houston.

032:49:21 McCandless: Roger. Apollo 10, this is Houston. Maneuver PAD. Flyby SPS/G&N: Noun 47, weight, 93353; plus 0.93, minus 0.21; 070:44:20.27. Noun 81 stuff; plus 0225.6, minus 0032.7, minus 0526.3; 102, 351, 017; HA, HP not applicable, Delta-VT 0573.6, 1:17, 0568.5; sextant star 40, 222.1, 33.4; the boresight star block, not applicable. Noun 61, latitude, minus 26.36, minus 165.02; 1180.4, 36171; GET of 0.05G; 166:23:38. Your GDC align stars; Vega 36, Deneb 43; roll align, 148, 013, 018; no ullage. Remarks: this PAD is based on the PTC REFSMMAT docked configuration. Your height of pericynthion will be 886 nautical miles following this maneuver. CSM weight, 62634; LM weight, 30719. Read back. Over.

032:52:07 Cernan: Okay. Purpose is flyby, SPS/G&N: 93353; plus 0.93, minus 0.21; 070:44:20.27; plus 0225.6, minus 0032.7, minus 0526.3; roll is 102, 351 and 017, Noun 44, NA. Are you with me?

032:52:38 McCandless: Roger. So far correct.

032:52:42 Cernan: 0573.6, 1:17, 0568.5; 40, 222.1, 33.4; boresight star is NA; latitude is minus 26.36, minus 165.02; 1180.4, 36171; 0.05G is 166:23:38.

032:53:10 McCandless: Roger. So far so good.

032:53:13 Cernan: Vega is 36, Deneb 43, 148, 013, 018; no ullage. Based upon PTC REFSMMAT docked, gives us a flyby at 886 miles [1,640 km]. And the CSM weight is 62634 [lbs, 28,475 kg], LM weight is 30719 [lbs, 13,966 kg].

[An interpretation of the P30 PAD follows:

Purpose: This burn would be used in the event of an emergency. It would be fired 5 hours before the planned insertion into lunar orbit. At that point, Apollo 10 would be so near the Moon that it would be easier to allow Apollo 10 to continue and fly around the Moon.

System: The burn would be made with the SPS engine under the control of the Guidance and Navigation System.

CSM Weight (Noun 47): 62,634 pounds (28,475 kg).

Pitch and yaw trim (Noun 48): +0.93° and -0.21°.

Time of ignition, TIG (Noun 33): 70 hours, 44 minutes, 20.27 seconds, Ground Elapsed Time.

Change in velocity (Noun 81), fps (m/s): x, +225.6 (+68.8); y, -32.7 (-10.00); z, -526.3 (-160.4). These velocities are with respect to the Moon and the local vertical and horizontal that the spacecraft makes with that body.

Spacecraft attitude: Roll, 102°; Pitch, 351°; Yaw, 17°. This is with respect to the attitude of the guidance platform, itself aligned to a preferred REFSMMAT.

HA (Noun 44): As with the previous P30 PADs for returning to Earth, there is no value for HA (height at apogee); the apogee of the expected orbit is greater than the 9999.9 nautical miles value that the computer will display.

HP (Noun 44): As with the previous P30 PADs for returning to Earth, there is no value for HP (height at perigee).

Delta-VT (total velocity change): 573.6 fps (174.9m/s).

Burn duration or burn time: 1 minute, 17 seconds.

Delta-VC: 568.5 fps. (173.3m/s) This is the value to be entered into the EMS Delta-V display. A lower value, to take into account the extra thrust the engine imparts as it tails off, the EMS will stop the burn if the G&N system fails to do so.

Sextant star: Star 40 (Altair) visible in sextant when shaft and trunnion angles are 222.1° and 33.4° respectively.

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. Another important point is when atmospheric drag on the spacecraft imparts a deceleration of 0.05 G's.

Expected splashdown point (Noun 61): The landing on Earth is calculated to be at 26.36° South, 165.02° west, in the Pacific Ocean.

Range to go: 1,180.4 nautical miles (2,186.1km). This is to set up their EMS (Entry Monitor System) before re-entry. The crew need to know the expected distance the CM would travel after Entry Interface.

Expected velocity at Entry Interface: 36,171 fps (11,025 m/s).

GET of Entry Interface: Expected at 166 hours, 23 minutes and 38 seconds GET.

GDC align stars: Stars 36, Vega (in Lyra) and 43, Deneb (in Cygnus) are to be used to align the gyro assemblies if it is not possible to use the guidance platform for this purpose.

GDC align angles: x, 148°; y, 13°; z, 18°.]

032:53:36 McCandless: Roger, Apollo 10. Readback correct. And be advised that we are satisfied with the Delta-H values from the P23 sightings. Do not plan to update the value already loaded in erasable memory. Over.

[The revised Earth horizon altitude of 24km has already been loaded into the erasable memory.]
032:53:56 Cernan: Okay. Fine.

032:54:01 Young: Fine, Bruce. What was loaded?

032:54:04 McCandless: Roger. 24 kilometers was loaded.

032:54:09 Young: Okay. Thank you.

032:54:10 McCandless: So you were over and under, by about the same amount on 2 different days. We figured the first set of sightings is probably the more reliable one.

032:54:28 Young: Roger.

032:57:05 Cernan: Houston. I got the onboard read-outs.

032:57:10 McCandless: Roger. Go ahead.

032:57:14 Cernan: Okay. The cryo fans have been cycled, Batt C is 36.8; Pyro Batt A is 37; Pyro Batt B is 37; RCS ring A is 87 percent, B is 88, C is 92, and D is 86.

032:57:35 McCandless: Roger, 10. Understand battery Charlie is 36.8; Pyro batteries Alpha and Bravo are both 37.0; RCS Alpha 87, Bravo 88, Charlie 92, Delta 86. Over.

[The contents of the fuel cell cryogenic tanks have been stirred to preclude stratification. The re-entry battery C charge readout is 36.8 volts, CM pyro battery Alpha and Bravo are both at 37.0 volts. The RCS propellant levels are expressed as a percentage for each of the SM quads.]
032:58:00 Cernan: That's affirmative.

032:58:02 McCandless: Roger. Out.

[Very long comm break.]
PAO: This is Apollo Control at 33 hours, 7 minutes into the flight of Apollo 10. At the present time the spacecraft is 128,445 nautical miles [237,879 km] from Earth and the velocity is 4,528 feet per second [1,380 metres per second]. The Apollo 10 is continuing preparations for their sleep period which is due to begin about an hour from now, about 34 hours Ground Elapsed Time. They are somewhat ahead of the Flight Plan in preparations for the sleep period and could possibly begin a little before that time. Since our last report we have about 3 or 4 minutes of taped conversation with the crew which we will play back for you now.

PAO: During that conversation, the crew has passed up the information they would need in the event there was a loss of communications between now and the time, they would be approaching the Moon. With this information they would be able to do a flyby of the Moon at an altitude of about 886 nautical miles [1,641 km]. The information also included the figures they would need for a maneuver to be performed at about 70 hours into the mission to do that flyby maneuver. At 33 hours, 17 minutes, this is Apollo Control.

033:36:37 McCandless: Apollo 10, this is Houston. About all we've got left before you close up for the evening is your crew status report. Over.

033:36:50 Stafford: Okay, Bruce. We're just changing out the canisters at this time.

033:36:56 McCandless: Roger.

033:37:04 Stafford: We'll be with you in a minute.

033:37:21 Stafford: Okay. We’re going to end - terminate the battery charge at this time, and we'll purge the fuel cells.

033:37:29 McCandless: Roger. 10.

033:38:48 Stafford: Okay. Houston, Apollo 10.

033:38:52 McCandless: Roger, 10.

033:38:55 Stafford: Okay. With respect to anything out of the kit, the CDR had one Lomotil, CMP one Lomotil, LMP one Lomotil, and the LMP also had two aspirin.

[From the Apollo 10 Mission Report, August 1969 - "The crewmen took Lomotil to diminish the abdominal rumblings caused by the ingestion of hydrogen gas present in the potable water, since they were concerned that diarrhea might develop. The use of Lomotil, however, was not medically indicated; the drug decreases the propulsive activity of the lower intestinal tract and reduces the amount of gas that can be expelled."]
033:39:10 McCandless: Roger. Understand. One Lomotil each, and two aspirin for the LMP.

033:39:16 Stafford: That's correct.

033:39:21 McCandless: Do you have the personal dosimeter readings?

033:39:27 Stafford: Stand by.

033:39:48 Young: Okay. You can add one to mine. This is the CMP.

033:39:54 McCandless: Understand. CMP is plus one from the last one.

033:40:00 Young: That’s right.

033:40:02 Stafford: Okay. CDR. Forgot what the total was on the last one. Mine now reads 26029.

033:40:09 McCandless: Roger. 26029.

033:40:13 Cernan: And the LMP is 15031. I believe that's up one.

033:40:18 McCandless: Roger. And for your information, the last significant digit there is actually 1/100. Over. You're not moving much.

033:40:27 Cernan: Roger.

033:40:29 Stafford: No.

033:40:31 McCandless: Did you get the chlorine [garble] in okay?

033:40:37 Stafford: We're going to do that later on. We haven't gone to bed yet.

033:40:41 McCandless: Roger. Out.

033:40:42 Stafford: The only thing left open I can think of.

[Long comm break.]
PAO: This is Apollo Control at 33 hours, 41 minutes into the flight of Apollo 10. The spacecraft now at a distance of 129,918 nautical miles [240,607 km] from Earth and the velocity down now to 4,415 feet per second [1,346 metres per second] and continuing to drop slowly. The spacecraft weight right now is 93,353 pounds [42,441 kg]. A short while ago we heard from the crew with their daily status report and we'll play that back for you now and then stand by briefly for any further conversation.

PAO: Here in Mission Control at the present time Flight Director Milton Windier is polling the Flight Controllers to determine if they have any further information to be passed up to the crew before the crew begins their sleep period. We'll continue to stand by.

033:50:08 McCandless: Apollo 10, this is Houston. Over.

033:50:13 Stafford: Go ahead, Houston. Apollo 10.

033:50:14 McCandless: Roger, 10. We have nothing else for you at the present time. If you have no further transmissions for us, we'll bid you a good night and remind you to put the S-band normal mode voice switch to Off.

033:50:32 Stafford: Roger. The S-band normal mode switch to Off after we shut down here.

033:50:39 McCandless: Roger.

033:50:40 Stafford: Roger. And after that, we're going to [garble] Down Voice Backup?. We're going to chlorinate the water in a little bit, and then sack out.

033:50:46 McCandless: Roger. And if you need us give us a call on Voice Backup.

033:50:52 Stafford: Okay, Bruce. Sure will.

033:50:54 McCandless: Good night.

PAO: We appear to have lost lock from the spacecraft signal momentarily accounting for the noise on the circuit. During that one portion where the noise also came in on top of Tom Stafford we could make out Tom reporting that he did plan to begin the sleep period shortly and that he advised that the crew would chlorinate the drinking water supply before going to sleep and then would begin their sleep period. That rest periods scheduled to begin at about 34 hours, Ground Elapsed Time or about 10 minutes from now. At 33 hours, 51 minutes into the flight of Apollo 10, this is Mission Control.

Flight Plan Page 3-23

PAO: This is Mission Control at 34 hours, 34 minutes into the flight of Apollo 10, We've heard nothing from the crew since capcom Bruce McCandless bid them good night about 45 minutes ago. They're scheduled to be in a 9-hour sleep period, and we anticipate that they are either are or will be resting shortly. At the present time, Apollo 10 is 132,225 nautical miles [244,879 km] from Earth, and the velocity is 4,419 feet per second [1,347 metres per second]. This is Apollo Control, Houston.

Earth view GET 35 hours

The view of Earth from Apollo 10 at 35:00:00

PAO: This is Mission Control; now 35 hours, 32 minutes into the flight of Apollo 10. We've had no further conversations with the crew since our last report. I anticipate that they are sleeping at this time. The spacecraft is currently 134,651 nautical miles [249,372 km] from Earth and the speed is 4,352 feet per second [1,327 metres per second]. Out here in Mission Control the activity has also quieted down as would be expected. Flight controllers primarily observing the status of spacecraft systems and all of those seem to be functioning normally at this time. One of the displays that we have available to us shows the time at which the spacecraft will be crossing into the lunar sphere of influence. This is a somewhat arbitrary time but it is the point when here in Mission Control we will switch over from Earth-reference velocity and distance information to lunar-reference. That time is currently listed as 61 hours, 50 minutes, 49 seconds Ground Elapsed Time. At that point the spacecraft will be under this dominant influence of the Moon rather than Earth and the gradual decline we've been seeing in the velocity will reverse itself. The spacecraft will then begin to accelerate toward the Moon and under the dominant influence of the Moon's gravity. At 35 hours, 33 minutes; this is Apollo Control.

PAO: This is Apollo Control; 36 hours, 34 minutes into the flight of Apollo 10. And the spacecraft now 137,243 nautical miles [254,173 km] from Earth. The velocity is 4,282 feet per second [1,305 metres per second]. All continues relatively quiet here in Mission Control. All of our telemetry information from the spacecraft indicates that all systems are functioning normally. and we also are informed by the Flight Director that it has now been about 6 hours since the last thruster firing. As you recall, we set up with the crew a new procedure for maintaining Passive Thermal Control to minimize the thruster firing which interfered with their sleep last night. Apparently the modified Passive Thermal Control mode is working out very well. By way of additional information on the spacecraft status right now, the weight is 93,353 pounds [42,441 kg]. We'll continue to monitor and report to you any significant changes in status of Apollo 10. As said, everything continues to progress very well at this time. This is Apollo Control at 36 hours, 35 minutes into the flight of Apollo 10.

PAO: This is Apollo control at 37 hours, 34 minutes. The Apollo 10 spacecraft is now 139,716 nautical miles [258,753 km] from Earth, and the velocity continuing its very slow decrease, down now to 4,215 feet per second [1,285 metres per second]. Here in Mission Control, we are preparing to hand over shifts. Flight Director Milton Wendler will be relieved by Flight Director Pete Frank and his Orange team of flight controllers. We do not anticipate a change-of-shift briefing. Flight Director Windler summarized activities for us on this shift. Reports that continuous tracking since the midcourse correction, performed at 26 hours, 33 minutes, shows the trajectory to be very close to the nominal. He said we expect no further midcourse corrections en route to the Moon based on current tracking. And a new Passive Thermal Control mode now with a higher revolution rate, some 3 revolutions per hour. compared with the 1-revolution-per-hour thermal control used last night appears to be working well to minimize the thruster firings that disturbed the crews sleep last night. Wendler noted that we haven't observed any thruster firing since setting up this Passive Thermal Control mode more than 7 hours ago. Be also noted that we maintained good data flow from the spacecraft, which shows that all systems are functioning normally. This is Apollo Control at 37 hours, 36 minutes.

PAO: This is Apollo Control; 39 hours, 1 minute Ground Elapsed Time. Apollo 10, still en route to the Moon, is now at a distance from Earth of 143,201 nautical miles [265,207 km]. Continuing to decelerate now showing 4,123 feet per second [1,257 metres per second] in velocity. Cabin pressure aboard Apollo 10 is 4. - now at 4.9 pounds per square inch; temperature 75 degrees. A partial pressure of carbon dioxide in the cabin is now showing 1.2 millimeters of mercury. The only bioinstrumentation coming down on telemetry from the spacecraft is on the Command Module Pilot and his heart rate is in the high 50's - around 57; it fluctuates somewhat from time to time and a respiration rate of 8. Apollo 10 is being tracked at the present time through the Honeysuckle antenna. The handover to the Madrid antenna will take place at 41 hours Ground Elapsed Time. which will be about 2 hours from now. Some 3 hours, 57 minutes remaining in the sleep period. And at 39 hours, 2 minutes Ground Elapsed Time; this is Apollo Control.

PAO: This is Apollo Control; 40 hours and 1 minute Ground Elapsed Time. Apollo 10 presently is 145,602 nautical [miles, 269,653 km] away from Earth, upbound toward the Moon, continuing to decelerate. Velocity reading is now 4,063 feet per second [1,239 metres per second]. The so-called Moon sphere of influence, where the speed begins to increase again, will not take place until tomorrow at about 61 hours, 50 minutes Ground Elapsed Time. The Apollo 10 system status sheet that's put out by the spacecraft analysis people, and the one for the time of 39 hours Ground Elapsed Time, is quite brief. It covers a single page and most of the entries under the various systems say all systems performance - normal. In the cryogenic quantities of hydrogen and oxygen for the fuel cell, the tank 1 cryogenic hydrogen shows 79.7 percent remaining, tank 2, 81.4 percent remaining, oxygen tank 1, 82.4. tank 2, 82.7. In the batteries some 105.2 amp hour are remaining in batteries A, B and C. That's a total figure. All temperatures are normal in the modified Passive Thermal Control mode in which the spacecraft is being spun up a little faster than it was last night, now rolling up 3 revolutions per hour instead of 1 revolution per hour. And this faster rate apparently requires no additional attitude control by the digital auto pilot to keep the spacecraft oriented to proper direction where the sun angle is 90 degrees to the longitudinal axis of the spacecraft. Handover from the Honeysuckle antenna to the Madrid antenna is about an hour away. Two hours, 56 minutes remaining in the sleep period. And at 40 hours, 4 minutes Ground Elapsed Time; this is Apollo Control.

PAO: This is Apollo Control; 41 hours, 1 minute Ground Elapsed Time. Apollo 10 presently is 147,951 [nautical] miles [274,004 km] outbound from Earth. And just approaching 4,000 feet per second, 4,004 feet per second [1,221 metres per second], in velocity. Continuing to decelerate. In the Manned Space Flight tracking Network, we've just handed over to the Madrid antenna, Madrid, Spain, after having tracked for several hours with the big 85-foot antenna at Honeysuckle creek in Australia. The crew has less than 2 hours remaining in the sleep period - the present sleep period. We have 1 hour and 58 minutes remaining till wakeup time. All going well aboard the spacecraft; all systems still functioning normally; crew still asleep, no word from them in the past several hours since the sleep period began; and at 41 hours, 2 minutes Ground Elapsed Time; this is Apollo Control.

PAO: This is Apollo Control; 42 hours, 1 minute Ground Elapsed Time. Apollo 10 is now 150,000 miles - 150,257 nautical miles [278,274 km] away from Earth upbound toward the Moon, traveling now at a velocity of 3,948 feet per second [1,204 metres per second]. The crew is still asleep with less than an hour remaining of the sleep period. A bit whimsy here in one of the displays in the Mission Control Center, its actually a projection of pages of the Flight Plan on a large ten by ten background TV projector. They've borrowed Snoopy's dog house and show him asleep in the usual manner on his back on top of the dog house, and down toward the bottom of the page where it says "in sleep period" he's bailing out of the top of the dog house, jumping down to the ground. And other news about the next mission, Apollo 11, the Apollo 11 stack rollout to launch complex 39A at Kennedy Space Center has been delayed somewhat to install a protective cover, a raincoat sort of a device over the spacecraft stack. It's been some delay in getting this installed properly and its estimated the rollout will begin at 9:00 Central Daylight Time. And at 42 hours, 2 minutes Ground Elapsed Time; this is Apollo Control.

PAO: This is Apollo Control; 43 hours, 3 minutes Ground Elapsed Time in the mission of Apollo 10. Distance from Earth; 152,609 [nautical] miles [282,630 km]. Velocity now 3,891 feet per second [1,186 metres per second]. We've passed the time of the end of the sleep period. However we've heard nothing from the crew and it's not planned to give them a call until 44 hours unless they're first heard from here in Mission Control. At 44 hours the consumables update and Flight Plan update are scheduled as well as cycling the fans in the cryogenic storage tanks for oxygen and hydrogen and a few other items to take care of. Realignment of the inertial measurement unit and a change of the lithium hydroxide canister for removal of carbon dioxide from the cabin atmosphere. A discussion is going on here in the control center as to whether midcourse correction number 3 will really be necessary or not. The current track predicts pericynthion arrival on the back side of the Moon at 61 nautical miles [113 km]. Serious consideration is being given to not doing midcourse correction number 3. We'll continue to monitor the air-ground circuit and come up with the conversation when it does commence. And at 43 hours, 5 minutes Ground Elapsed Time; this is Apollo Control.

043:33:38 Young: Houston, Apollo 10. Transmitting on regular S-band Omni voice. How do you read? Over.

043:33:51 Lousma: Reveille! Reveille! All hands muster on the flight deck for calisthenics. How do you read?

043:34:01 Young: Loud and clear. We had a little trouble rousing up all hands this morning.

PAO: This is Apollo Control; 43 hours, 34 minutes; let's join the conversation in progress with Apollo 10.

043:34:13 Lousma: Well, we decided to let you sleep in, a little bit, and if you want to get up at your leisure, that's fine with us.

043:34:24 Young: Yes. Sort of looks like we've got a hard day of PTC. That thing didn't fire thrusters once last night. My hat's off to you. That's great.

[John Young is commenting that due to the revised PTC initiation procedure, no RCS firings were encountered during the rest period and that today would be a quiet day remaining in the PTC mode.]
043:34:35 Lousma: You were right. We were going to mention that to you, and it looks like a good way to go. That's a good solution.

043:34:46 Young: Economical, too. [Long pause.]

043:35:10 Lousma: Apollo 10, Houston. John, are you the only one who is up yet?

043:35:17 Unidentified Crew member: [Garble] on that one.

043:35:23 Lousma: Roger.

[Long comm break.]
PAO: This is Apollo Control, while we're waiting for the noise to be taken off the air-to-ground circuit, apparently its a data noise and a matter of shifting antennas. We've had word from the Cape that the Apollo 11 roll-out has been delayed to 11:30 AM Central Daylight Time; we'll continue to monitor the air-to-ground from Apollo 10, and leave the circuit open. This is Apollo Control. While we are waiting for the air-to-ground conversation to continue, the distance from Earth is now displayed as 153,929 nautical miles [285,075 km], velocity now 3,860 feet per second [1,177 metres per second].

043:40:05 Lousma: Apollo 10, Houston. When you get settled down and get breakfast there, we've got some information just to pass along, when you've got time to listen.

043:40:25 Young: Roger. I better go down to the end compartment and hold reveille.

043:40:28 Lousma: Say again, please.

043:40:35 Young: I said I've get to go back to the aft compartment and hold a little reveille.

043:40:49 Stafford: Hello, Houston. Apollo 10.

043:41:09 Lousma: Good morning, Apollo 10. This is Houston. How do you read?

043:41:18 Stafford: Loud and clear. Hey, this is really a great place to sleep on the way to the Moon, I'll tell you.

043:41:24 Lousma: Well, we let you sleep in, a little bit. Have a good rest?

043:41:30 Stafford: Yes. About 9 hours solid.

043:41:34 Cernan: Good morning, Jack. How are you?

043:41:36 Lousma: Good morning. Great shape. Understand you are a little slow on reveille this morning.

043:41:44 Cernan: Yes. If we had known you were down there, we probably would have heard the bugle.

043:41:48 Lousma: I expected to hear your feet collectively hit the deck before I finished reveille.

043:42:00 Cernan: Pretty hard to find out which way the deck is, up here. How does the spacecraft look to you?

043:42:11 Lousma: The spacecraft is in real good shape. The CSM and LM systems are both in very good health, and your consumables are considerably ahead of your Flight Plan. During the night - During the night with this PTC mode, since initialization yesterday at about 30 hours, there were no jet firings.

043:42:36 Stafford: Roger. We could tell that last night; it doubles our analysis that we haven't fired one thruster since we started. Looks like we have a real winner here, Jack.

043:42:45 Lousma: Roger. That was a good solution. And also, you are riding right down the slot. Your third midcourse correction would be seven-tenths of a foot per second, and so we are recommending deletion of that, and your present perilune, prediction without midcourse 3 is 61.8 nautical miles [114.5 km] at 76 hours.

043:43:11 Stafford: Reset. Sounds great.

043:43:16 Lousma: And, in addition, your data on both Command Module RCS rings remains the same; your leak rate on ring number 1 is the same as yesterday. And, when you have time to listen, we've got a little bit of news down here.

043:43:39 Stafford: Why not go ahead while we are fixing breakfast? Might as well listen to the news.

043:43:45 Lousma: Okay. You are right in the headlines. Among the biggest of news events of yesterday, were the three astronauts of Apollo 10. Millions of people throughout the world saw some or all of what one wire-service writer called the "Mini show". Tom Stafford was called the star, and John Young the supporting player, because he appeared upside-down throughout the show. Gene Cernan was listed as camera man. A now unemployed philosopher has pointed out that due to your efforts color television has reached new heights. Coleman Hawkins, jazz saxophonist, died at the age of 60. He was one of the innovators of Be-Bop during the late 1940's. President Nixon is reportedly in favor of keeping the 10-percent surtax past its deadline of June 30, 1969. His spokesman, speaking to a House of Representatives committee, proposed that the 10-percent surtax be extended to the end of this year, and then lowered to 5 percent. President Nixon also announced that he will meet with South Vietnamese President There within the next 2 weeks, probably at Midway Island or some other Pacific Ocean location. In the sports world, there were no major league baseball games played yesterday. Gardner Dickinson won the National Invitational Golf Tournament at Ft. Worth on Sunday with a two-under-par 278. The PGA tour moves to Atlanta this week for the Atlanta Classic.

043:45:31 Lousma: One closing note of special interest to the Apollo 10 crew is this story: Chief Winnie Red Fox of Philadelphia, who remembers his Uncle Crazy Horse fighting at the Little Big Horn, would like Man to leave the Moon alone because it's ruining the rainfall. The 99-year old Ogalala Sioux Chief summed up his reaction to the Apollo 10 moonshot in this manner, and I quote: "It doesn't seem to rain much since man started messing around with the Moon." (Laughter) And we're tracking you guys out there now at 154,221 miles, and you have slowed down to 300 - 3,000 - correction 3,853 feet per second.

043:46:25 Cernan: Hey, Jack, pass the word. I don't think I'll be able to slip back in time for the Classic at Atlanta.

043:46:31 Lousma: Roger. There wi11 be another time,

043:46:34 Stafford: Also, Jack, would you pass the word on to the Indian chief that I grew up in the Dust Bowl in Oklahoma, but I still don't think flying to the Moon has anything to do with the rainfall.

043:46:46 Lousma: Roger. We'll pass the word, Tom.

043:46:48 Young: It's always nice to - to run across somebody who's not a proponent of the atomic theory of weather production.

043:47:11 Cernan: We haven't had a chance to look out here and give you much of a weather report, yet.

043:47:18 Lousma: Roger. We're standing by, and how's that Moon look? Is it getting bigger?

043:47:24 Cernan: I'm sort of afraid to look.

043:47:27 Stafford: We still have all the window covers on since we just woke up.

043:47:32 Lousma: Roger. Relax and have your breakfast and let us know when you are ready to press on with the plan of the day.

043:47:38 Stafford: Roger.

PAO: This is Apollo Control. While the crew is eating breakfast the various updates to the Flight Plan are being passed to the spacecraft communication Jack Lousma here in Mission Control. Looks like a rather leasurely day according to the Flight Plan, and especially if it is finally decided to delete the midcourse correction number 3. Jack Lousma mentioned to the crew that the needed correction was something like 7/10 of a foot per second [0.2 metres per second] in Delta-V, or velocity change, and that the predicted pericynthion on arrival at the Moon at 76 hours, that's the pericynthion of course would be on the side opposite the Earth. would be something like 61 nautical [miles] [113 km] which is 1 [nautical] mile [1.8 km] off the desired pericynthion. We'll come back up when the conversation resumes and at...

043:49:32 Cernan: Jack, here comes the world. Looking right over Suez Canal, Saudi Arabia, the Mediterranean, Africa, back into the parts of Europe.

043:50:04 Lousma: Houston. Roger. [Long pause.]

043:50:53 Cernan: Jack, right now I'm looking at all of Africa, which is almost totally clear with the exception of a few clouds on the western side. I can see across the Straits of Gibraltar, some cloud cover just on the eastern side of the Straits. I can see Spain which is totally clear, Portugal, almost all of the Mediterranean except the north - northwest corner of the Med, Greece, Crete, Turkey, Italy. They all look clear from here. Saudi Arabia, back up into the Soviet Union, is partially clear in great areas and actually almost back into parts of China where the terminator is, it's just sort of partly cloudy. There appears to be a big, long, wide cloud swirl out into the Atlantic west of Spain. Generally, it looks like I can see Zanzibar. Generally, it looks like that whole portion of Africa and eastward – northeastward - is pretty clear today.

043:52:02 Lousma: Roger. Thank you, Gene, for the weather report.

043:52:11 Cernan: And - and it's a magnificent sight, Jack. Beautiful.

PAO: That was Gene Cernan giving a global weather report, what's visible from the spacecraft. Projecting a line from the center of the Earth out through the surface to where the spacecraft is, its present position is over Saudi Arabia approximately 20 - 27 degrees north by 50 degrees east. We'll continue to monitor in case there is further conversation but it's unlikely there will be too much as they are now preparing their breakfast meal. They'll settle down to business in probably another 15 or 20 minutes with a crew status report, consumables update, Flight Plan update, also a state vector fed up to them from the ground, and go through a realignment of the Inertial Measurement Unit for the day's activities, after having been in the rotisserie, or Passive Thermal Control mode, all night, in which under the new scheme, there was not a single thruster firing to keep them awake during the night. And at 43 hours, 54 minutes Ground Elapsed Time; this is Apollo Control.

PAO: ...further conversations; let's come back up on the loop.

043:54:23 Young: Houston, this is 10. The LM/CM Delta-P gauge is reading 1.4 today.

043:54:29 Lousma: Roger. Copy 1.4. Thank you.

[Long comm break.]
PAO: This is Apollo Control, while we are waiting for conversation to resume with the crew of Apollo 10, we'll pick up the days activities on the Flight Plan. Canister change, lithium hydroxide canisters which remove the carbon dioxide from the cabin atmosphere scheduled at about 46 hours. Fuel cell oxygen and hydrogen purge at about the same time. Noon meal at 47 hours. Environmental control system redundant component check at 48 hours, 25 minutes. At 52 hours, state vector update from the ground, also maneuver PAD and target load for midcourse correction number 3, should it actually be carried out. And just prior to the time for the midcourse correction, another alinement of the Inertial Measurement Unit. The midcourse correction, if it is done, will come at 53:45 Ground Elapsed Time. TV pass scheduled at 54 hours, running 15 minutes, this is through the Goldstone station in California. Distance at the time of this pass will be 176,000 nautical miles [326,000 km] from the Earth and 39,000 nautical miles [7,200 km] out from the Moon. In about 56 hours, 30 minutes, the crew starts powering down, and what's called the pre-sleep check list, stowing all the gear, chlorinating all the water, cycling the fans in the cryogenic storage tanks in the Service Module, crew status report going into the sleep of communications, another canister change, and at 58 hours Ground Elapsed Time, they would begin a 10-hour rest period. We'll leave the circuit open for any further conversation between bites of the crew's breakfast.

PAO: Considerable amount of line noise on the air-to-ground circuit, probably indicating a need to shift Omni antennas. Except for a brief period of realigning the Inertial Measurement Unit, most of the day will be spent in the Passive Thermal Control mode.

PAO: This is Apollo Control. The predicted closest approach to the Moon for the third stage of the Saturn V, which injected the Apollo 10 spacecraft into translunar coast, will come tomorrow, Wednesday, at about 6:42 Central Daylight Time at a distance of 1,779 nautical miles [3,295 km], sweep on by the Moon, go into solar orbit. The line noise has decreased somewhat on the air to ground. We will continue to monitor here as the crew has their morning meal.

Flight Plan Page 3-26

044:04:12 Stafford: Houston, Apollo 10. We're ready to copy the consumables update when they're available.

044:04:50 Stafford: Hello, Houston. Apollo 10.

044:04:56 Lousma: Apollo 10, this is Houston. Here we go with the consumables update. At GET 44 plus...

044:05:04 Stafford: ...Jack?

044:05:06 Lousma: Say again, please.

044:05:09 Lousma: Apollo 10, Houston. How do you read?

044:05:11 Stafford: Go ahead.

044:05:15 Lousma: Roger. The consumables update...

044:05:16 Stafford: Roger. Reading you loud.

044:05:17 Lousma: Consumables update at GET of 44 hours, RCS total 86 percent, Alpha 85 percent, Bravo 85 percent, Charlie 86 percent, Delta 86 percent, H2 total 42.7 pounds [19.4 kg], O2 total 526 pounds [239 kg]. We’d like today, in order to balance the RCS up, to use AC roll instead of BD roll. Over.

044:05:56 Stafford: Roger on the consumables, and we will switch over to AC roll instead of BD roll.

[To balance out the RCS propellant quantities, MCC-H is requesting the crew switch to using the RCS roll jets on quads A & C. Switching to A & C using power bus MNA (Main A) or MNB (Main B) will energise jets A1, A2, C1, C2.]

Click on above image for full panel diagram.

044:06:01 Lousma: Houston. Roger. And this is 4 percent above the Flight Plan on RCS.

044:06:07 Stafford: Roger. [Long pause.]

044:06:39 Stafford: Houston, Apollo 10.

044:06:43 Lousma: Go ahead, 10.

044:06:46 Stafford: Roger, Jack. Wish you'd pass on to Chris and Johnny Mayer that we think that this attitude for the PTC is really great because you can see the Moon for just - and also the Earth - for just about a half of each rev; it's really tremendous.

044:07:01 Lousma: Roger. Copy, Tom.

[Very long comm break.]
PAO: This is Apollo Control. Stafford's reference there to the PTC really being great, meaning Passive Thermal Control Mode, that is that it was modified. He wanted to pass the word on that is was really great to Chris - meaning Christopher Kraft, who's Director of Flight Operations here at Manned Spacecraft Center and to Johnny Mayer, who heads up the Mission Planning and Analysis Division, the mathematicians and trajectory planners who come up with all the numbers associated with planning the missions. We'll continue to monitor the air-to-ground loop for any further conversation from Apollo 10.

PAO: This is Apollo Control. Down at the Spacecraft Communicator's console, the Flight Activities Officer is conferring with the Spacecraft Communicator Jack Lousma on the Flight Plan update, giving him all the necessary information to read up to the crew when they are ready to take the update. Standing by for resumption of air-to-ground communication.

PAO: This is Apollo Control continuing to monitor the air-to-ground for resumption of conversation. The spacecraft communicator Jack Lousma, within the next several minutes, likely will start reading up the Flight Plan activities, updates on the day's Flight Plan activities, to the crew. Sorting out the last details of the few minor changes. Here in the Control Room. before Lousma begins the Flight Plan update reading, the circuit is still open on air-to-ground to Apollo 10.

044:29:18 Stafford: Hello, Houston. Apollo 10.

044:29:23 CapCom: Go ahead, 10.

044:29:27 Stafford: Okay, Jack. There's one thing we'd like for you to pass on to the Project Office and it's been about the only type of thing we want to pass on in real time as up to this day on the system and again that's due to the water. There was lots of air in it on the initial servicing, and it's continued just to get [garble] just a little bit, and the little handheld centrifuge, all it does is slink the big bubbles to the bottom. I guess there's something about physics we don't understand, but if you could pass that word on to them and get working on it and save some time, save about -oh - 7 or 8 days for our debriefing.

[From the Apollo 10 Mission Report, August 1969 - "One system anomaly that resulted in considerable crew discomfort throughout the mission was the quantity of bubbles in the potable water system. These bubbles resulted in a bloated feeling in the stomach which gave all three crew members the continual feeling of just having eaten a full meal."]
044:30:05 Lousma: Roger. We'll get the word to them, Tom, and also we have a Flight Plan update when you're finished with breakfast.

044:30:14 Stafford: Okay. It'll be about another 15 minutes.

PAO: This is Apollo Control. Apparently the crew is still in the midst of eating breakfast, not quite ready yet to take the Flight Plan update from the Control Center here. At 44 hours, 35 minutes; this is Apollo Control.

PAO: This is Apollo Control. Let's join the conversation in progress with Apollo 10.

044:46:24 Cernan: Hello, Houston. Apollo 10.

044:46:27 Lousma: Go ahead, 10. This is Houston.

044:46:31 Cernan: Jack, just after I put the H2 and O2 fans on, we got a Cryo Pressure light. I guess it could be H2 tank 1 or O2 tank 2 at this time.

044:46:44 Lousma: Roger. We copy.

044:46:52 Cernan: And, it just went on at this time.

044:46:56 Lousma: Roger. Understand you have a Cryo Press light. Is that affirmative?

044:47:00 Cernan: And I'm [garble]. Yes, it just went out now. It - it came on just as I cycled - turned the fans on, and now it's out. And I'm ready to copy that Flight Plan update.

[When the Cryo PRESS light is illuminated it indicates cryogenic tank pressures:

Hydrogen 220 psia or below, or 270 psia and above. The yellow caution & warning (C&W) light illuminated if either or both H2 are above or below the proper pressure limits. The H2 tank pressures can be monitored using the meters on panel 2-Cryogenic Tanks Pressure H2 1 and 2.

Oxygen 800 psia or below, or 950 psia and above. The yellow caution & warning (C&W) light illuminated if either or both O2 are above or below the proper pressure limits. The O2 tank pressures can be monitored using the meters on panel 2-Cryogenic Tanks Pressure O2 1 and 2.]

Click on above image for full panel diagram.

044:47:11 Lousma: Roger. Here's the Flight Plan update. We'd like for you to initiate charge on battery A, and we'd like to have you give us a Mark. And at 51:45 we have a waste-water dump due.

044:47:33 Cernan: That's 51:45?

044:47:35 Lousma: That's affirmative. And, we're standing by for your crew status report and your PRD [Personal Radiation Dosimeter] readings.

044:47:58 Cernan: Okay. We'll give you the dosimeter readings first.

044:48:02 Lousma: Roger. Go ahead.

044:48:07 Stafford: Okay, Jack. Mine reads 26030.

044:48:13 Lousma: 26030

044:48:15 Young: 5030 on the CMP.

044:48:18 Lousma: Say again.

044:48:20 Young: 5030 on the CMP.

044:48:24 Lousma: Understand, 5030.

044:48:25 Young: 5 - affirmative.

044:48:29 Cernan: And the LMP is 15033. That's up 2 from 10 hours ago,

044:48:34 Lousma: 15033. Then a report on how you rested last night.

044:48:52 Young: Tom was sleeping on his back and Gene was sleeping on his stomach and I was sleeping in the couch. And that's how we did it.

044:49:02 Lousma: Sounds pretty simple.

044:49:04 Young: And it was great. It was great.

044:49:09 Cernan: Yes, Jack, LMP probably got about 6 to 8 hours of pretty good sleep.

044:49:15 Lousma: Roger. Copy. That's good.

044:49:21 Cernan: Okay. And you want a Mark on when to start charging A. Is that correct?

044:49:26 Lousma: That's affirmative.

044:49:46 Cernan: Okay. I'm ready to - to charge battery A right now.

[Re-entry battery A.]
044:49:51 Lousma: Roger.

044:49:56 Cernan: And the charge is On.

044:49:59 Lousma: Roger. Charge, On.

044:50:31 Cernan: Houston, is that all the Flight Plan update?

044:50:37 Lousma: Apollo 10, Houston. Affirmative. That's the end of the Flight Plan update for now, and we're about ready to go on a state vector update and would like to have the computer. Over.

PAO: This is Apollo Control. While we're waiting for the antennas to get sorted out for this state vector update, the space digitals display shows the altitude now, or distance from Earth, at 156,728 nautical miles [290,259 km]. Velocity continuing to decelerate, 3,794 feet per second [1,157 metres per second]. We will continue to monitor air-around to Apollo 10 as the conversation resumes.

044:51:00 Cernan: Okay.

[Long comm break.]
044:55:10 Lousma: Apollo 10, Houston. We're ready to uplink your state vector now if you'll go to Accept on your up-TLM. Over.

044:55:17 Stafford: We're Accept in P00.

044:55:21 Lousma: Roger. And I have a couple more items on Flight Plan update when you're ready to copy.

044:55:27 Cernan: Go ahead, Jack.

044:55:31 Lousma: Okay. We had, on our sextant calibrations during P23, some differences in Delta-H from yesterday and the day before, and we need to check the trunnion bias to use if it's drifting. In order to do this, we'd like you to, either before or after your P52 [IMU alignment] which is coming up, to do the steps of P23 which refer to the sextant calibration. And you can use any star, and I have the steps for performing this without going through the whole P23 if you need them. In addition, we've noticed, as you have, an imbalance in our hydrogen Cryo tanks; namely, that tank number 1 is lower than number 2. And we'd like to reverse this imbalance by reversing the heater configuration. However, we'd like to do this on our mark so that we can get the heaters in the proper point in the cycle. And so, when the time comes up, what we'd like you to do is turn off the heaters in tank number 1 and turn the heaters in tank number 2 to Auto on our mark [See 45:55:10]. Over.

[The sextant trunnion bias angle is a function of angle between the Landmark Line Of Sight (LLOS) and the Sun and is a constant if the Sun is outside of a cone + or -15 deg from LLOS. Whilst in P23, routine 57 (R57) is used to calibrate the navigation optics. This calibration measures the effect of solar radiation on the sextant trunnion angle and stores measured trunnion bias for P23.



The servo system that drives the movable line of sight (also called the Star Line Of Sight (SLOS)) had to be calibrated by having the LLOS point to a star and superimposing the same star over it using the movable line of sight. This means the trunnion angle is at a true zero and the computer can store a value for difference between this and the mechanical zero (known as the "trunnion bias").]

044:56:54 Cernan: Okay. Standing by for your Mark.

044:56:58 Lousma: Roger. It'll be a while before this time comes up.

044:57:04 Cernan: Okay. Let us know, and we'll do it.

044:57:06 Lousma: Roger. It's likely to be as much as half an hour. And, do you copy the information regarding the trunnion bias check?

044:57:20 Cernan: Roger. We'll do the steps in P23 that refer to the sextant calibration, either before or after P52.

044:57:28 Young: And we don't need any data on how to do that.

[Comm break.]

Earth view GET 45 hours

The view of Earth from Apollo 10 at 45:00:00

045:00:01 Lousma: Apollo 10, Houston. The uplink to state vector is complete, you can go to Accept. Correction, you can go to Block.

045:00:14 Stafford: We're in Block.

[Very long comm break.]
PAO: This is Apollo Control and the circuit is still open to Apollo 10. However, the line noise is rather strong now as they break lock and rotating around in the Passive Thermal Control mode with the Omni antennas. In spite of the noise we will continue to monitor the air/ground circuit and leave it live.

PAO: This is Apollo Control. The crew of Apollo 10 apparently is still in the midst of the realignment of the Inertial Measurement Unit. Meanwhile the spacecraft is now 157,476 nautical miles [291,644 km] away from Earth. Velocity is now 3,777 feet per second [1,151 metres per second]. The trajectory as tracked now shows that the pericynthion at arrival of the Moon will be some 61 nautical miles [113 km], and this is one reason that the midcourse correction number 3 stands a good chance of not being done at all. Members of the Black Team of flight controllers are in the process of taking over from the Orange Team here in Mission Control. At each console there is a miniature briefing session going on as each man tells his relief about what has been happening during the night, the status of the systems, and any other thing that the man needs to know to do his job during the day. We'll continue to monitor the air-to-ground circuit to assume that the crew will call the Control Center here when they are through with their task of aligning the platform to continue any discussion, possibly more global weather reports.

045:17:16 Young: Houston, Apollo 10.

045:17:22 Lousma: Apollo 10, Houston. Go ahead.

045:17:27 Young: Roger. I don't know if the GUIDO is watching this or not on the high bit-rate or whatever, but what I'm doing here is taking advantage of the PTC to check this celestial - to check the planet optional. I've already got Jupiter and you can recognize it because of its Moons, and now I'm, looking for Mars.

045:18:00 Lousma: Roger. We copy. Thank you.

[Comm break.]
045:20:53 Young: Tom has the Earth out his window, and that's the reason for the Program Alarm, and got Mars vector in there and it's open by Tom's window.

045:21:04 Lousma: Houston. Roger.

[Very long comm break.]
PAO: The Atlantic area should have widely scattered showers for the next two days. The outlook for the end of the mission area is satisfactory. End of the mission area is 15 degrees, 7 minutes south latitude by 165 degrees west longitude, in the southwest Pacific some 345 nautical miles [639 km] due east of Pago Pago, Tutuila. in American Samoa. Continuing to monitor air-ground with Apollo 10. Circuit is still live.

045:32:23 Young: Okay, Houston. We've just checked Saturn, and it's definitely recognizable because of the rings, of course, and it's pretty close to the Sun for a data point, I think, but it's easily visible.

045:32:40 Lousma: Roger, 10. We copy.

[Comm break.]
045:33:51 Young: Houston, this is 10. We can't do that optics calibration without stopping our PTC. Over.

045:34:00 Lousma: Roger. Stand by.

045:34:05 Young: I guess everybody knew that, didn't they. We did the realign while we still had PTC, and it seemed to work okay.

045:34:16 Lousma: Stand by one, please.

[Comm break.]
045:35:34 Stafford: Houston, Apollo 10.

045:35:40 Lousma: Apollo 10, Houston. We thought we were going to come out of PTC to do the P52. There is no need at this time to do the sextant calibration. We can do that when you come out of PTC for the television later on in the Flight Plan. Over.

045:36:04 Stafford: Hello, Houston. Apollo 10.

045:36:07 Lousma: Go ahead, 10.

045:36:11 Stafford: Okay, Jack. Just for a minute to look ahead in the Flight Plan, are we still planning the fuel cell H2 purge after 46 hours?

045:36:25 Lousma: Houston. That's affirmative.

045:36:29 Stafford: Okay. We'll go ahead and get the H2 purge line heaters on as called in the Flight Plan.

045:36:36 Lousma: Roger. We copy. And did you copy my last about the sextant calibration? Over. [Long pause.]

045:37:37 Lousma: Apollo 10, Houston.

045:37:43 Cernan: Go ahead. Over.

045:37:44 Lousma: Roger, Did you copy our last about the sextant?

045:37:49 Cernan: Go ahead, Houston.

045:37:51 Lousma: Roger. This is Houston, 10. Did you copy our last about doing the sextant calibration when we come out of PTC for the television as opposed to doing it now? Over.

045:38:00 Young: Negative. We didn't. I was just fixing to get Arcturus, and do it on Arcturus. Looks like that would be a good one.

045:38:07 Lousma: Roger. We had...

045:38:08 Young: That's fine with us. There's no sense in - we'd kill two birds with one stone that way.

045:38:14 Lousma: Roger. We prefer not to interfere with the PTC. This is not - The sextant calibration is not time critical; however, we thought that you would come out of PTC to do the P52, so let's hold off on the sextant calibration until the TV pass. Over.

045:38:40 Young: Roger. That sounds fine to us.

045:38:44 Lousma: Houston. Roger.

[Long comm break.]
045:43:27 Duke: Hello, Apollo 10. Houston. Over.

045:43:35 Young: Good morning, there.

045:43:36 Duke: Good morning, you guys. Your friendly Black Team's coming back on duty for the daylight hours, and we got one thing for you. When you did the call-up of the P52, John, you collapsed your deadband. We'd like you to widen it again out to the 30 degrees. Over. When you get through the 52.

045:43:58 Young: Okay. What we did was - Yes. Well, we just went to pitch and yaw in Accel Command, and with this thing not coupling, it doesn't - you know, it doesn't make any difference, Charlie. But we're going to establish the deadband back when we get done.

[When they entered Verb 37, the crew made the deadband smaller.]
045:44:12 Duke: Roger.

045:45:31 Young: Houston, this is 10. As a result of that P52, sort of "on the fly," so to speak, the Auto optics is not positioning the stars right in the center of the reticle. They’re of – they’re within the lines but they're not in the center like they usually are, so I'd like to do another realign whenever we stop for TV or whatever, and we can get that optics calibration at the same time.

045:46:07 Duke: Roger, John. I'm pretty sure we'll concur. Stand by. Yes, 0...

045:46:14 Young: I don't - I think it's good - It's within the R and M lines on the sextant which is really pretty good. In fact, it puts all the planet options inside the sextant field of view with no problem at all. We checked three options: Jupiter, Mars, and Saturn; and it put them all right in there.

[John Young is confirming that as part of the P52 procedure the Command Module Computer (CMC) is pointing the sextant satisfactorily at planetary targets, which can be used as a substitute for stars. Young was having problems locating identifiable stars, due in main to sunlight reflections entering the optics off the LM. By pointing the optics at a brighter target such as a planet it is then possible to locate identifiable stars known to be in close proximity to these targets.]
045:46:44 Duke: Roger. We copy. We concur if you want to do the P52 - another one - down after the TV when we do the sextant cal. You can do it if you want to. Over.

045:46:59 Young: Okay. And I think this one's okay. I just want to verify it from the torquing angle.

045:47:05 Duke: Roger. Can you give us your torquing angles and your star angle differences there?

045:47:23 Stafford: Okay, Charlie. We used star 36 and 44. The star angle difference was four balls 1. The torquing angles: X was plus 00431; Y, minus 00366; Z, minus 00063.

045:47:47 Duke: Roger. Thank you much, 10. We had data dropout during the time, and we couldn't copy it. Thank you.

045:47:58 Stafford: Roger.

045:48:00 Duke: Was that on or about 45 or 44, thereabouts, Tom?

045:48:07 Stafford: Okay. It was 45:06:30.

045:48:13 Duke: Roger.

045:48:26 Young: What it was, Charlie, was I did the first P52 using the stars, and then checked the planet options without actually using those to align, with.

045:48:38 Duke: Okay 10. I copied

045:48:45 Young: So the actual realign was kind of early this morning.

045:48:48 Duke: Roger. Before we came in. Thank you.

[Long comm break.]
PAO: This is Apollo Control at 45 hours, 49 minutes. The Black Team of Flight Controllers led by Flight Director Glynn Lunney has gone on duty in the Mission Operations Control Room. The CapCom is Charlie Duke. Apollo 10's distance from Earth; 158,780 nautical miles [294,059 km]. Velocity; 3,747 feet per second [1,142 metres per second]. We will continue to stay up live.

045:52:17 Duke: Hello, Apollo 10. Houston. We're ready to configure the Cryo H2 heaters, if you're standing by.

045:52:27 Cernan: Okay, Charlie. All set.

045:52:30 Duke: Roger. On my Mark, it's - Stand by. Roger, 10. On my Mark it's tank 1 heaters Off, tank 2 heaters Auto. Stand by.

045:52:45 Duke: Mark.

[Comm break.]
045:54:43 Duke: Hello, Apollo 10. Houston. Over.

045:54:47 Cernan: Go ahead, Charlie.

045:54:49 Duke: Roger. I think we lost you with the antenna switch there, Gene-o. Did you copy the Mark on the heater switch?

045:54:58 Cernan: No, I'm sure we did lose you. Go ahead.

045:55:00 Duke: Roger. On my Mark, H2 tank 1 heaters to Off, and tank 2 heaters to Auto. Stand by.

045:55:10 Duke: Mark.

045:55:11 Cernan: Okay.

045:55:15 Cernan: Okay, you got it. H2 tank 1 is Off, and H2 tank 2 is Auto.

[The cyrogenic hydrogen tank heaters are being switched over from one tank to the other. The heaters are used to maintain the required operating pressure (245 psai) as the quantity reduces. The Master Alarm is triggered when the tank pressure exceeds 270 psia or falls below 220 psia. The heater switching has been timed so that this Master Alarm sounds during the crew active period rather than during their sleep period.]
045:55:20 Duke: Roger. And the EECOMs say that during the day here you probably can expect some Master Alarm's from this configuration, due to the heaters, but it should set us up for the night so it won't be, they won't wake you up tonight with the same things. We'll back to normal...

045:55:37 Cernan: Okay. That's great.

045:55:38 Duke: Yes. We’ll go back to normal configuration for pre-sleep.

045:55:47 Young: Roger. Houston, we reinitialized these deadbands quite a ways from our 90-degree point. And we probably ought to reinitialize them when we get back around 90 degrees. Do you concur?

045:56:00 Duke: Stand by.

[Long comm break.]
Flight Plan Page 3-27

046:01:26 Duke: Hello, Apollo 10. Houston. On reestablishing the deadband: when you went to Accel Command, you really didn't hurt a thing. When you selected the Verb 37 you collapsed it, but we noticed that you've increased your deadband and it's still established plus or minus 30 degrees around 90 degrees on the pitch; so, we're still in good shape. Over.

[Verb 37-change program, during P52 IMU realignment procedures.]
046:01:50 Stafford: Roger, Charlie. Sounds real good. Thank you.

046:01:53 Duke: Roger.

[Long comm break.]
046:09:13 Cernan: Hello, Houston. This is 10.

046:09:15 Duke: Go ahead, 10.

046:09:19 Cernan: Okay. I'm ready to purge the H2, if you're ready.

046:09:22 Duke: Roger. Stand by.

046:09:25 Duke: We're ready, 10. Go ahead.

[Long comm break.]
046:14:05 Cernan: Houston, the H2 purge is complete. The line heater is Off.

[Purging is a function of power demand and gas purity. O2 purging requires 2 minutes and H2 purging 80 seconds. A hydrogen purge is preceded by activation of the H2 Purge Line HTR switch on panel 3, 20 minutes prior to the purge.]

Click on above image for full panel diagram.

046:14:12 Duke: Roger. Copy. Hey, Gene-o, did you guys have any - Have you had any trouble with the canister changes?

046:14:23 Cernan: No. We're about to make one right now. I don't think we've had any trouble. Stand by.

046:14:27 Duke: Roger. The only reason I asked was I remember during the C-squared F-squared, we had some sticky ones, and was wondering how it was going.

046:14:43 Stafford: Thus far, Charlie, none have stuck.

046:14:46 Duke: Roger.

[Very long comm break.]
PAO: This is Apollo Control at 46 hours, 23 minutes. Apollo 10 has just passed the 160,000-mile mark. Current distance; 160,014 nautical miles [296,344 km]. Velocity; 3,719 feet per second [1,134 metres per second]. Flight Director Gerry Griffin will take over a large part of the duties today from Glynn Lunney. They are both at the Flight Director's Console, but Gerry will handle a large part of the duties, freeing Glynn for activities in preparation for Lunar Orbit Insertion day tomorrow and the subsequent lunar orbit activities including rendezvous. We'll continue to stand by live, for any transmissions from Apollo 10.

046:40:28 Young: Hello, Houston. This is 10.

046:40:32 Duke: Go, 10.

046:40:36 Young: Roger. I'm making a report on that optics tracking that we did this morning, catching it during the REFSMMAT. On the - While we're still in PTC REFSMMAT realign, the optics tracking is about 10 to 20 times smoother and easier than it is in the simulator. It's just beautiful. The optics tracking is absolutely no problem on medium speed in putting sign right in the middle of the reticle and working on it – just fantastic

046:41:08 Duke: Roger, John. We copy. In medium speed it's really easy to track the star and put it right in the center. How's the visibility...

046:41:19 Young: This Auto optics has just been working - Well, there's still no way to recognize stars from P51s that I can see other than - Probably you could do it if you put the whole Lunar Module and point it directly at the Sun. In other words, if you went to gimbal lock or something like that, then you could point the - If you didn't have any other recourse, you could point the whole Lunar Module right at the Sun, and I think that would shield you enough so that you could recognize stars as constellations. But other than that, I haven't seen a single star or constellation through the telescope that I can recognize by itself.

[The automatic optics positioning is controlled by the CMC routine R52. It is used to point the star LOS (SLOS) optics at a star or landmark define by a program or by crew input via the DSKY. The routine is automatically selected either during the IMU realign program P52, the rendezvous navigation program P20, by the orbital navigation program P22 or by the cislunar navigation program P23. In this discussion, John Young is referring to its use in P52.]
046:42:06 Duke: Roger. Thank you for that report. We'll pass it on.

046:42:18 Young: Well, there's nothing we can do about that; I'll tell you that. But it’s sure comforting to see those things like constellations, you know.

046:42:25 Duke: Yes. I know what you mean there if you dump that platform. This optics tracking is good news, though, if we can make that thing a lot easier.

046:42:41 Young: Well, it saves you quite a bit of fuel, because to reinitialize that REFSMMAT - reinitialize that PTC is probably going to cost you a little.

046:42:50 Duke: Roger. You don't think the three-tenths of a degree has - Didn't give you any trouble, did it, when you first got started there? Is it a little learning curve?

046:43:07 Young: We're looking at about 2500, maybe a little less right now. No, there's no problem at all with it.

046:43:14 Duke: Great...

046:43:15 Young: It's easy. And the Auto optics track the stars, too.

046:43:17 Duke: Right. This thing has really - I don't know whether you guys can tell it or not, but if you - The thing is really coupling up great. It looks like our angular momentum vector is just right off - just off the roll axis, and the thing goes off in pitch a little bit back into yaw, and then the yaw goes off as the pitch decreases. And it looks like we're going to be rock-solid here as long as we want to stay.

046:43:43 Young: Right. I don't know who thought of it, but it sure works good.

046:43:47 Duke: Roger. It took us a little while to get it...

046:43:50 Stafford: It's interesting to note that, even though we haven't fired a thruster up here for the past 12 to 15 hours, this whole stack has a little motion all to itself.

046:44:00 Duke: Roger.

046:44:02 Stafford: [Garble].

046:44:07 Duke: 10, you're fading out so we'll switch your antennas and get a better signal. Over.

046:44:13 Young: Yes. Ever so often the whole stack just gives a little shudder. I don't know what it is.

PAO: This is Apollo...

046:45:25 Young: Another thing that we were concerned about that doesn't seem to be a problem is that the LM on - except for a temperature from - except for reducing the brightness that prevents you from seeing stars and recognizing as constellations – actual occlusion of the telescope and sextant - doesn't appear to be near the problem it was thought to be when we started.

046:45:48 Duke: Roger. Good show. Does it look like what the pictures that you had been shown, John?

046:45:57 Young: Yes. It actually looks even less than that, and it's a good deal less than the thing we had - worst-case - fixed up in the simulator to practice with.

046:46:07 Duke: Roger. If you'll put your artistic talent to work - when nothing to do - the next couple of hours, how about sketching us up a little view so we can maybe update the CMS when we get back down, and maybe they can put a little cut-out in there and get their picture to be real-life. When you guys – We switched antennas on you. And, Tom we lost most of your conversation about the thrusters. If you'd like to repeat that, we're standing by,

046:46:41 Stafford: I guess John amplified it some more, Charlie, that even though we haven't fired a thruster for, I'd say, 12 to 15 hours now, this stack has a motion all of its own. And on occasion, you'll get a little shudder in it, a little noise, and we are getting very sensitive now, and acclimated to every little motion. And it is amazing that the whole stack has its own little motions and noises in it.

046:47:04 Duke: Roger. We copy.

046:47:07 Stafford: We didn't know the glycol pumps to the suit [garble] sounds like it might be some tank slosh or something of the nature, but it's really amazing how we can pick up these little things. Occasionally the whole thing will just give a little shudder.

[In the Crew Technical Debrief-2nd June 1969, the crew discussed the oscillations they encountered during the trans lunar coast.]

[John Young - "Even without thruster firing, or several occassions-for unknown reasons-we'd be sitting there on the second night and no thrusters would be firing, and the whole stack would suddenly give a shimmy. It was quite recognisable, because we're all sensitive to zero gravity - unexplainable, but apparently quite normal. The whole stack would sort of resonate up and down. It was kind of weird, but very interesting."]

[Tom Stafford - "It might have been some fuel sloshing in the Lunar Module, but it had its own noise. You could hear things rumbling around, and it had its own little vibrations in there. It was a low frequency vibration. Now, we never felt that on the Command Module coming back (from the Moon). It was when we had the LM on there. Also, with the LM onboard, when you fire a pulse (again the Apollo 9 crew briefed us on this) the whole stack seems to be a very loose structural model."]

[John Young - "It'd set up this frequency and it'd shake the whole works. Nothing you could see on the rate needles, but you could feel it."]

[Tom Stafford - "We timed it, and it would go through about 4 cycles. It would damp down to zero in 3½ to 4 cycles."]

046:47:19 Duke: Roger. I was talking to the 9 crew this morning about it, and they said they had the same sensations when the LM was out front - that anytime they came up with any little movement, that the whole thing just seemed to shudder. We're - It's really amazing to sit here and watch how you're coupling up in pitch and yaw and the PTC - The thing is that it never gets out of more than 20 degrees off from our initial attitude, then couples back in, and goes the other way. We think we are in pretty good shape.

046:47:56 Stafford: Yes. Sounds like you came up with a real great solution here to save fuel and everything, so far as the PTC goes. Also, like I passed on to Jack this morning, this attitude is fantastic because we can see the Earth for about half of each one of our revs here.

046:48:10 Duke: Hey, well, really great. Is the old orb getting a little bit smaller out there?

046:48:18 Stafford: You can tell we're a long ways from home now, Charlie.

046:48:21 Duke: Roger. I bet it was the SPAN people that came up with...

046:48:25 Stafford: Say, as a matter of fact...

046:48:28 Duke: I was going to say it was the SPAN people that came up with the PTC procedure, so once we got it straightened out on how to read it up to you, things seem to be working real great. We are all real pleased with it.

046:48:43 Stafford: Yes. It feels good in the air, and looks good as far as the attitude for the outside reference - We're getting a lots of pictures of the Earth. And, also, the main thing, we're saving fuel.

046:48:52 Duke: Roger. Are your sequence cameras and the Hasselblad working okay?

046:49:00 Stafford: Working slick as a whistle.

046:49:01 Duke: Beautiful.

046:49:05 Stafford: Say, Charles. I was wondering - We got a little time to kill here. Again, each day we've been going over our lunar activities, just doing homework up here, about a couple hours each day, so we'll be well ahead of the game when we get there, at least try to be. But one thing you people have never seen is Africa, and we got High Gain lock. We can call Verb 64 and we'll show you a picture of what Africa looks like and you can - or I assume that we are working through Madrid now.

[Verb 64 is used to commence routine 05 to calculate S-band antenna angles. Using routine 05, the crew compute and display the two angles required by the steerable S-band antenna to point it at the centre of the Earth. It can only be used when the IMU is running and aligned. Stafford has mentioned it in relation to transmitting TV signals to the MSFN Madrid ground station.]
046:49:29 Duke: Stand by. That's affirmative. We're coming through Madrid. Would you like to just put it on when you come around with High Gain and not stop the PTC?

046:49:42 Stafford: Yes. We don't want to stop the PTC. We want to save every ounce of fuel we can. We can show you just a few minutes of it, since we've got some time to kill here in the High Gain out through the hatch window and the side window. We'll have to get configured.

046:49:54 Duke: Stand by, 10. Let's see if we get the networks configured right. Okay?

046:50:01 Stafford: Alrighty.

046:50:53 Stafford: Houston, Apollo 10.

046:50:57 Duke: Go ahead, 10.

046:51:01 Stafford: Okay. Just to reiterate: the only two anomalies we’ve seen on the whole spacecraft - and by and large, the spacecraft is just performing beautifully - are these two items. I called one of them down to Jack and you heard about the other one, but just to summarize them - one was when the Mylar insulation, you know, kind of blew out of the tunnel hatch when John pressurized the LM. Then second one is all the air in the water. Now that was the initial servicing of the water at the Cape. As soon as we got into orbit, the stuff had lots of air in it. That's continued to bug us just a little bit, but those two are about the only - the major things now that they can start working on before we splash down.

[The bubbles in the drinking water was discussed by the crew in the Apollo 10 Mission Report, August, 1969 - "The one system anomaly that resulted in considerable crew discomfort throughout the mission was the quantity of bubbles in the potable water system. These bubbles resulted in a bloated feeling in the stomach which gave all three crew members the continual feeling of just having eaten a full meal."]
046:51:40 Duke: Roger. We'll pass it on, Tom, and we're going to start on that. 108 [CM-108, Apollo 12] has got a hydrogen separation in it and, hopefully, it's going to work. I don't know what we can do about it for 107 [CM-107, Apollo 11], but we will pass this on and see what they can come up with. This TV stuff - we don't...

046:52:00 Stafford: Okay, Charlie...

046:52:01 Duke: I was going to say, the TV stuff, we haven't got any lines called up and any time scheduled for the satellite right now, but Madrid is configured to record the stuff and then we can play it back later. Over.

046:52:17 Stafford: Okay. We will just give them about a short, 5-10-minute setup and then you can take a look at it later.

046:52:23 Duke: Roger. If you will stand by, we will have you some High Gain angles for you.

046:52:30 Stafford: Okay. I don't think you've ever seen Africa and Saudi Arabia and that part of the world yet, have you?

046:52:36 Duke: Negative. Is it real clear down there at this time?

046:52:41 Stafford: Yes. Africa is great. It looks like, though, that all of Europe, the Soviet Union, all down through the Balkans are socked in that giant cloudcover you saw yesterday. But Saudi Arabia, India, and all of South Africa is completely open, and the intertropical convergence zone is really beautiful. You can really see the total line down there, so we will just give you a quick picture of it.

046:53:06 Duke: Roger. Fine. We will let you know when Madrid is configured and we will have you some angles in a moment.

046:53:13 Duke: Later on, when we've got some time, we have got a few things we would like to discuss with you on the LOI, part of the LOI on your cue cards and some mission rules. Over.

046:53:29 Stafford: Okay.

046:53:30 Young: That's a good idea, Charlie.

046:53:32 Duke: Roger. And we will be up with that...

046:53:36 Young: I was just about to ask you if...

046:53:37 Duke: Go ahead, John.

046:53:43 Young: Okay. I was just about to ask you, in view of the chamber pressures a little lower than nominal, if we didn't want to hedge a little on that chamber pressure that we talked about the other day. I don't know.

046:53:56 Duke: Well...

046:53:57 Young: ...Maybe our gauge reading is just low.

046:54:01 Duke: Roger. I think - kind of think it's right, on our second cues, after the manual Repress attempt for propellant Press less than 160, we don't believe that if you see that first cue – propellant Press less than 160 - that the PC is going to actually got that low. You know, as we see in sims, it really didn't go that low. That's a soft point on the second cue and also in the mode 1 and 2 regions, second from the bottom down there with the SPS injector valve closed after command on. With the one bank, you know we saw PC of about 95 on the evasive maneuver, and with one bank actually closed, that PC down to less than 80 is really not a good indication. And what we're recommending is that if you have, as an example, bank B is closed or appears closed on your panel, then you close bank A. And if you're still burning, then you've had an instrumentation failure, obviously, and turn bank A back on and keep burning. If it shuts down, then you should abort anyway. Over.

Click on above image for full panel diagram.

[The Service Propulsion System (SPS) engine combustion chamber pressure can be monitored during firings using the LVa/SPS PC indicator on panel 1. This dual purpose indicator could be set to one of two positions via the LV/SPS IND switch also on panel 1. In the a position the indicator displays a percentage of the Delta P measured by the Q-ball which is a function of pitch and yaw. The range of the indicator was from 0 to 150 %. Small changes in air pressures are sensed through eight holes in the Q ball. The indicator is monitored from 50 seconds to approximately 1 minute and 40 seconds after liftoff.]

[In the SPS PC position the indicator displays the SPS chamber pressure as a % from chamber pressure transducer on injector of engine. Indicator range from 0 to 150%. This range corresponds to 0 to 150 psia chamber pressure. The normal chamber pressure range is between 95 and 105 psia.]

046:55:13 Stafford: Okay. I think we've got that. We'll talk about it a little more.

046:55:17 Duke: Okay. I just wanted to let you start thinking...

046:55:19 Stafford: ...Why don't you give us what you have?

046:55:23 Duke: Keep talking, Tom. Go ahead.

046:55:27 Stafford: Okay. And what we'd like to know is - it'll take you a little time to dig it up - what did you indicate on telemetry for the thrust chamber pressure when we had both banks on yesterday during that midcourse?

046:55:35 Duke: Stand by. I saw 95, but let's see what the descript chart says. Hang on. The engine was perfectly normal [garble] Tom, at 100 psi.

046:55:45 Stafford: Okay. Real good. Looks like we have about - gauge error bit of around 5 psi in here.

046:55:56 Duke: Roger. I just wanted ya’ll to start thinking about these - the cue card, and we'll get all squared away down here and let you - And when we get some time, we’ll discuss. I'll let you stand by for the angles and the network configuration.

046:56:13 Stafford: Okay.

046:56:15 Young: Charlie, would you please - You got through that conversation before I could get the cue card out.

046:56:19 Duke: I figured that's what vas happening about halfway through. Since I was - had a one-track mind down here, I just kept talking. Stand by. I think we’ve got some angles for you.

046:56:31 Cernan: You sure do get excited, Charlie.

046:56:44 Stafford: That's okay. We just love to hear you keep talking.

046:56:47 Duke: Okay. Hey, we've got some angles for you. If ya’ll go yaw 270, pitch 45, you should be able to pick this up right now.

[These are HGA pointing angles to enable TV signal transmission.]
046:57:30 Cernan: Okay, Charlie. How are you reading High Gain?

046:57:32 Duke: Reading you five-by, Gene.

046:57:38 Cernan: Okay. I have to wait a couple of minutes for the world to come around.

046:57:40 Duke: Roger.

046:57:59 Duke: Hello, 10. Houston. Madrid is standing by. You can turn on the tube any time.

046:58:20 Stafford: Okay. Looks like we're going to be a while before the Earth gets, around here [garble] as soon as the Earth gets bright, we can see a beautiful Moon [garble].

046:58:38 Duke: Hello, Apollo 10. You're barely readable. We request - If you read me, request you go Narrow Beam.

046:58:50 Cernan: Charlie, we are Narrow Beam. How do you read?

046:58:54 Duke: Roger. Reading you five-by now, Gene. Tom's conversation was unreadable, however.

046:59:01 Cernan: Okay. Well, we've been Narrow Beam ever since we locked up.

046:59:07 Duke: Roger. It's - Comm's beautiful, now.

PAO: This is Apollo Control. We will not receive this television transmission live. It will be recorded at the Madrid tracking station. As soon as we have an estimate on when we will be able to replay this transmission will notify you. The satellite is not available to us at the present time for live transmission.

046:59:56 Duke: Hello, Apollo 10. Houston. We request that you give us a Mark when you turn the TV on, so Madrid will get the word.

047:00:07 Cernan: TV is on the interior now until we can get the world to come around.

047:00:11 Duke: Roger.

047:00:31 Duke: 10, Houston. Madrid is getting your FM [garble] carrier.

047:00:41 Young: You say they are receiving?

047:00:47 Duke: Roger. It's weak now, but they're picking up your interior shots.

PAO: Madrid reports a fairly good signal now. Apollo 10's distance; 161,363 nautical miles [298,843 km]. Velocity; 3,689 feet per second [1,125 metres per second].

047:00:50 Cernan: Okay.

047:02:09 Cernan: Okay, Charlie. We got the world now out of Tom's window, and it looks - pretty small in our monitor right now. And we'll try zooming it.

047:02:17 Duke: Roger. Madrid is copying.

047:02:21 Cernan: Okay. It's going out of sight there, and we’ll shoot a little bit of interior and then it ought to come inside my window here in a minute or two.

047:02:30 Duke: Roger.

[MP3 audio file.]
047:03:15 Cernan: Interior-wise, we're giving them a look at the star chart which has got some colors of both the Earth, the Sun, and the Moon, and some of the planets: Saturn, Jupiter, Venus, Mars.

047:03:30 Duke: Roger. How about putting that pretty patch up there again?

047:03:40 Cernan: Okay. We'll do that.

047:04:05 Stafford: Tell them this is our star chart and how we identify the stars and the planets that we're looking at right now.

047:04:11 Cernan: This is what we use...

047:04:14 Duke: 10 Houston...

047:04:16 Cernan: ...for our star navigation. The Earth is over here - Go ahead.

047:04:19 Duke: Roger. Our signal's down about...

047:04:21 Cernan: ...Go ahead, Houston. This is 10.

047:04:22 Duke: Roger, Gene-o. Our signal strength is down about 10 dB. We'd like you to go High Gain to Medium width and then back to Narrow. Over.

047:04:36 Cernan: Okay. It's Medium, and now I'll go back to Narrow

[The High Gain Antenna (HGA) can be used in three modes - Wide, Medium, Narrow. In the wide mode, the center feed horns are used for transmission and reception of signals. In the medium mode, one of the parabolic dish reflector antennas is used for transmission and all four of the dish antennas are used for reception of S-band signals. The narrow mode employs the four parabolic dish antennas for transmission and reception of S-band signals. MCC-H is trying to optimise the signal strength of the TV transmission and is requesting the crew to cycle between the Medium and Narrow modes.]
047:04:40 Duke: Roger.

047:04:44 Cernan: How's that.?

047:04:47 Duke: Stand by.

047:04:50 Cernan: Okay. The blue ball here, the big one, is the Earth as it progresses through the - through the heavens here while we're on this trip. The Moon is in yellow, and it also progresses through the heavens.

047:05:17 Cernan: Might bring out the famous Apollo 10 symbol patch.

047:05:22 Duke: Roger. We'd like to - Wish we were seeing this now, but Madrid is going to record it for us and then we'll see it later on. That was a beautiful astronomical description of the star chart there, Gene.

047:05:38 Cernan: I thought you could follow it a little bit closer there, Charlie, if I told you about that.

047:05:43 Duke: Roger. Takes me a little while to catch on to those things.

047:05:49 Cernan: Where better can you give an astronomical description than in the astronomical heavens?

047:05:53 Duke: (Laughter)

047:05:54 Cernan: I think that's where we are.

047:05:59 Young: This PTC REFSMMAT really helps you with the orientation of the stars, both - even if you can't see them you can - you can have a feel for where they ought to be, which is - I think - is going to help us out.

047:06:18 Duke: Roger, 10. We're still having problems locking up, so we'd like to have you go to Wide Beam for 30 seconds and then back to Narrow. Over.

047:06:33 Cernan: Okay. We're in Wide Beam.

047:06:36 Duke: Roger. We'll probably lose the TV for a little while. We’d like you to keep going the next time around, and maybe we can get a better picture. Madrid is having a little bit of trouble.

047:07:35 Cernan: Charlie, you - You wouldn't believe this, but right now outside my window I've got something. I don't know how far. I assume it might be the S-IVB, just spinning around in reflected sunlight out there.

047:07:49 Duke: Roger. If we get our expert FIDO's on - on going and compute and see how far away the S-IVB should be right now from you.

047:07:58 Cernan: Well, I can see it with the naked eye, and then I put the monocular on it and I can see it spinning around. I wouldn't bet my life on it being the S-IVB, but it sure has - sure has got to be something like it.

047:08:12 Duke: Roger. We hope so. We could - We'd like you to go back to Narrow Beam width now, 10.

047:08:18 Cernan: Roger. We're back in Narrow now. Charlie.

047:08:23 Duke: Okay. And we're getting a great signal strength now, so we should be in good shape if you can give us one more pass on the - on the tube. We – We should get a good picture at Madrid.

PAO: That was Gene Cernan reporting that sighting.

047:08:58 Duke: 10, Houston. Madrid is reporting a much better picture now. So we fixed it up.

047:09:06 Cernan: Okay. The Earth ought to be coming through my window here in a minute, Charlie, if you can stand by.

047:09:09 Duke: Roger. We're standing by.

047:09:26 Duke: 10, Houston. EECOM are saying that it looked like we looked up on side low there the first time when we acquired with the high gain. Request that you stay in the Wide Beam width - for about 30 seconds, or a little bit longer before you select Narrow. Over.

[MP3 audio file.]
047:09:49 Cernan: Okay. We're all right now, though?

047:09:51 Duke: Roger. We’re in good shape now. That was just for future reference.

047:10:33 Cernan: For all the folks at home, that should be a pretty good picture of the Stars and Stripes.

047:10:39 Duke: Roger. Wish we were seeing it.

047:10:58 Duke: 10, Houston. We are expecting High Gain loss in about 1 minute. Over.

047:11:06 Cernan: Okay. And here comes the Earth. Let me get it for you first.

047:11:54 Stafford: Okay. Now we've got it, Charlie.

047:11:57 Duke: Roger. We've got about - still about a minute...

047:11:58 Stafford: ...taking a good picture of the Earth right now.

047:12:04 Duke: Roger. Madrid's got it.

047:12:24 Cernan: Okay, Charlie. That's maximum zoom. You should be seeing all of Africa - Matter of fact you should be looking right down at Madrid.

047:12:30 Duke: Roger. We're beginning to lose the High Gain...

[Due to the spacecraft still being in the PTC, the High Gain Antenna (HGA) is no longer able to maintain the narrow-angle pointing at Earth required for good TV signal transmission.]
047:12:32 Unidentified Crew member: [Garble].

047:12:34 Cernan: [Garble] antenna.

047:12:38 Duke: Roger. We're beginning to lose the High Gain Antenna, 10. We're going to Omni.

047:12:41 Young: Okay. That's a shame, cause it sure is pretty.

047:12:44 Duke: 10, Houston. If you'll go to Manual on the High Gain, and we'll switch to Omni.

[The HGA pointing angles can be manually input if the High Gain Antenna Track switch is set to the Manual position.]

Click on above image for full panel diagram.

047:12:55 Cernan: You're there.

047:12:57 Duke: Roger. We have them.

047:13:07 Cernan: Boy, she’s in a perfect spot now, Charlie; that was a shame.

047:13:13 Duke: 10, Houston. Due to our lock-on side-lobe problem, about a quarter or half of that pass was a little weak, at Madrid. If you'd like to, Madrid is still configured, and next time you come around, they'd like some more TV. Over.

047:13:30 Stafford: Okay. We got plenty - We got plenty of time here, and we're just going through reading about the lunar activities. And how soon before we can get High Gain lock-on?

047:13:44 Duke: Stand by.

047:13:52 Duke: It'll be approximately l0 minutes, 10.

047:13:59 Stafford: Okay. We'll note that, and let us know as soon as we have high gain locked. We should be able to get it out the hatch window and my side window.

047:14:05 Duke: Roger. And we'll come up with some more angles for you in just a minute.

047:14:13 Stafford: Okay.

047:14:22 Duke: Apollo 10, Houston. If you've got your LOI abort card out, we can talk about it.

047:14:38 Cernan: Okay. We got it out, Charlie.

047:14:41 Duke: Okay. Second line down, after manual Repress attempt, your first cue - propellant Press less than 160 [psia] and you got the second cue listed as PC less than 80 [psia] that's a soft number. We don’t think on the basis of sims and systems data that you'll see a PC down that low, with the propellant Press down at 160 [psia] and [garble] below that before we get down to 80 [psia]. So, just think about it, and it's a soft number and we can discuss this later on; what we want - whether we want to scratch that or not. The only other comment on the card was down at – next to the bottom - was mode 1 and 2 only. On the SPS injector valve Close, after commanded On. Your second cue again is PC less than 80 [psia]. If you'll recall the evasive burn, we were getting a PC of about 95 [psia] or thereabouts. So, that's really soft on that one. We suggest that we eliminate that cue and that we replace it with a statement that says, "Close the bank that indicates Open," and if you're still burning, it's an apparent instrumentation failure. If the engine shuts down, then you're in abort mode anyway, and you’d continue with the LOI-1, mode 1 abort, at the proper time using one bank. Over.

[The crew have been reading through the lunar orbit activities for much of day two, in preparation for the upcoming events. Meanwhile MCC-H have been considering the next major maneuver, the LOI-1 SPS (Lunar Orbit Insertion-1, Service Propulsion System) burn. They are clarifying with the crew the parameters that must be closely monitored by the crew prior to and during the LOI-1 SPS burn. Two parameters they are particularly highlighting are the SPS propellant tanks pressures and the SPS chamber pressure PC. The SPS propellant tanks pressures should be between 170 and 195 psia. See the detail of the PC indicator and pressure range at 046:54:01.]

[Should there be a need to abort the LOI-1 burn prior to ignition or during the burn, the Flight Mission Rules would dictate the procedure to be followed.

From the Apollo 10 Final Flight Mission Rules, April 1969 - Item 3-30

"During the LOI burn, the flight crew will take the following action:

A. Terminate LOI for the following SPS problems (perform the 15-minute abort if the burn is terminated in the Mode 1 or Mode 2 region):

*See malfunction procedure #1

1. Loss of one GN2 bottle (<400 psi) and decay in the other (terminate only while in the Mode 1 or Mode 2 region).
2. Pressure decay in either SPS propellant tank to 140 psi (after manual repress attempt).
*3. Fuel - Oxidizer Delta-P>20 psi.
*4. Chamber pressure <80 psi or decay of 10 psi during the burn.
5. Any ball valve(s) fails to open after its respective bank is commanded on or fails when closed (terminate only while in the Mode 1 or Mode 2 region).
6. Flange temperate light."]

[From the Operational Abort Plan for Apollo 10 mission F - "Mode 1 is a one-impulse maneuver that returns the spacecraft directly to Earth. The burn is initiated as soon as possible after LOI-1 termination to reduce the necessary Delta-V.

The mode 1 abort region is defined as the class of preabort trajectories from which a one-impulse abort maneuver initiated as soon as possible will result in Earth return. The constraints are time of ignition and abort Delta-V. The abort Delta-V available during the LOI burn is shown in figure 8-6

for an SPS burn, CSM only; for an SPS burn, CSM/LM; and for a DPS (Descent Propulsion System) burn, CSM/LM. The fuel-critical, unspecified area (FCUA) mode 1 abort requirements are shown in figure 8-7(a)

for several times of abort initiation. The required abort Delta-V increases rapidly as the abort is delayed from LOI termination. The GET of landing for these FCUA aborts is presented in figure 8-7(b).

However, rather than return to an FCUA, a return to the prime landing area would be more acceptable if it were available. The mode 1 abort delta V for returns to the MPL is shown in figures 8-8(a) through (c) at a GET of 118 hours, 142 hours, and 166 hours, respectively, for various delay times.




Mode 2 is a two-impulse maneuver that necessitates one lunar orbit. The first impulse is directed down the radius vector and is initiated as soon as possible. The burn reduces the orbital period and provides a stable intermediate lunar orbit. The second burn occurs near pericynthion and injects the spacecraft on the trans-Earth trajectory.

The mode 2 abort occurs in a region in which the required mode 1 abort Delta-V exceeds the available Delta-V and in which a stable lunar ellipse has not yet been achieved. The mode 2 abort consists of an initial DPS burn (corrective maneuver) to provide a stable intermediate ellipse and a second DPS burn to inject the spacecraft on the transEarth coast. The corrective maneuver consists of a variable Delta-V magnitude (Delta-V1) that is directed down the radius vector. The time of ignition is nominally LOIIG (LOI ignition) plus 2 hours.

Mode 3 is a one-impulse maneuver initiated near pericynthion after one or more orbits. This burn is similar to the normal TEI burn.

047:16:23 Cernan: Okay. Let me write that down, and we’ll go over it here.

047:17:03 Young: Charlie, I’m just looking through our rendezvous procedures here, and I just wondered if those guys have any second thoughts about some of those procedures. You know, we can change them now, but in a couple of days we won’t be able to.

047:17:15 Duke: Stand by.

047:17:21 Young: Charlie. I'm just kidding about the changes.

047:17:26 Duke: (Laughter) Okay. We - We really did go through them. We took the backup set last night, and from cover to cover, and everybody's happy as a clam with all the procedures now, finally.

047:17:43 Stafford: We're even [garble] satisfied with your Marking schedule.

047:17:47 Duke: Say again Tom.

047:17:53 Duke: I told Tittle not to have any more data priority meetings.

['Tittle' is a nickname given to Howard W. Tindall Jnr, Chief of Apollo Data Priority Coordination and author of the Tindallgram memos.]
047:17:57 Duke: He is locked out of the MOCR right now. We refuse to let him in.

047:18:07 Duke: Back to the LOI abort card, my first statement, after manual Repress attempt with propellant Press less than 160 [psia], we think we should substitute as a second cue, instead of the PC less than 80 [psia], there, that if you can confirm a drop in PC, then that's enough to indicate a true propellant pressure drop, and it would be enough to shut down on. Over. 10, Houston. Would you select Omni Charlie for us?

[Duke is confirming the crew should consider a low SPS chamber pressure as a cue indicating a low propellant pressure that would dictate a premature manual shut down of the SPS engine during the LOI 1 burn.]
047:20:33 Duke: 10, Houston. Have you got any thoughts on the updates for your LOI-1 abort card? Or, do you want to think about it some?

047:20:47 Cernan: Let us think about it for a minute, Charlie. Based upon that PC which we saw, with single bank, I guess maybe you got a point.

047:20:54 Duke: Roger. We'll be standing by any time on this. We'll have you some High Gain angles momentarily for your next pass around.

047:21:11 Stafford: Okay.

047:21:25 Cernan: Hey, Charlie. I bet the - I bet the FIDO has an LOI PAD for us, doesn't he? Right now?

047:21:33 Duke: Say again, 10. I cut you out.

047:21:37 Young:  I said I was betting that FIDO has an LOI-1 PAD for us right now.

047:21:42 Duke: He’s working on it; we got some - FIDO says he's got your - the S-IVB about 3,970 [nautical] miles [7,350 km] away.

047:21:55 Cernan: Well, that must be it, then, that I saw, because it's really reflecting and tumbling out there.

047:22:02 Duke: Roger.

047:22:05 Cernan: If you can see that far, but there's something out there.

047:22:19 Young: Is there any way you could give us a vector to it? We could put it in the AUTO optics and let it go look for it.

047:22:31 Duke: Stand by. We've got a yaw of - a yaw of 270 and a pitch of plus - plus 30 for the High Gain at 24 [047:24:00] for the lock-on. Over.

047:22:35 Cernan: Okay. We'll be with you.

PAO: This is Apollo Control at 47 hours, 23 minutes. The Manned Space Flight Network [MSFN] expect to be able to feed that television signal from Madrid to Houston in approximately 12 hours. There is a 12-hour reservation time for INTELSAT 3, the communications satellite through which the signal will have to be fed. The MSFN...

047:24:13 Cernan: Hello. Houston. We should be locked on Narrow now in High Gain.

047:24:20 Duke: Roger. And our signal strength looks great, 10.

047:24:25 Cernan: Okay. You should be having something here pretty quick.

047:24:30 Duke: Roger.

PAO: Madrid is receiving TV again now.

047:24:58 Duke: 10, Houston. Madrid has a good TV picture.

047:25:02 Cernan: Okay.

PAO: The picture is being received in black and white in Madrid. It will be converted to color here in Houston. The Manned Space Flight Network says it will attempt to get the signal back here as soon as possible, but they estimate it will be approximately 12 hours.

047:26:04 Duke: 10, Houston. The picture is still looking great at Madrid.

047:26:30 Cernan: Charlie, the Suez Canal appears now to be going into darkness. We're looking at most all of Africa, the Mediterranean Sea, Spain, Portugal are in view. So the folks down in that part of the area ought to be getting a good picture of themselves right now.

047:26:49 Duke: Roger. I think they can [garble] that stuff out...

047:26:54 Cernan: The whole [garble].

047:26:55 Duke: I was just going to say, Gene-o, I think they can [garble] that stuff out in black and white live. For the color, it has to come over here, be converted, and then be transmitted back into color for the people over in that area, but they're probably seeing it in black and white.

047:27:12 Cernan: Well, it's a beautiful sight. All of Africa is brown again, of course, and the waters are very, very blue.

047:27:19 Duke: Can you differentiate between the - the...

047:27:22 Cernan: Looks like it...

047:27:24 Duke: Go ahead. I'm sorry.

047:27:31 Cernan: Charlie, our picture just went off beyond the corner of our window now, so it looks like that's about it for right now.

047:27:37 Duke: Roger.

047:27:39 Cernan: And what did you want me to differentiate between?

047:27:41 Duke: I was just going to ask you, looking at Africa...

047:27:46 Cernan: What was your question, now?

047:27:48 Duke: Okay. Looking at Africa, could you tell the difference between the Congo and the tropical forests and the - and the - say, the mountains around Morocco and all the Atlas Mountains, and up around the Mediterranean, or is it all sort of the same brownish color?

047:28:02 Stafford: No, the - Once you get to the tropical rain forests, it changes colors. You can definitely see the Sahara and the Atlas Mountains. When you go south of the rain forests it's not as green as you would expect, but it gets a less red and more of a, really a purplish-green tinge there, Charlie.

047:28:23 Duke: Roger.

047:28:25 Cernan: You don't see the great - the bright - the bright green rain forest you'd think you might, but it's the shade – it's the contrast that you notice.

047:28:34 Duke: Yesterday when we were looking at South America live here, you could see the - above the timberline in the Andes Mountains, just very distinctly - a Brownish color, and in the - in the Amazon Basin and in the jungles around it, it was sort of a - a deep bluish, darker than the ocean by a considerable factor, but it was more of a bluish tinge down here.

047:29:04 Stafford: No, it's - It's a purplish-bluish tinge, and we can see - again, a lot of it has to do with the amount of haze and cloud cover on it.

047:29:10 Duke: Roger.

047:29:14 Cernan: Charlie, it sounds to me like you're seeing it pretty much as we are.

047:29:17 Duke: It was really spectacular color, 10. We're really - Everybody is really pleased and happy with the quality. All the networks and all are just ecstatic over it, as we are here in the room. It's – You guys have really been putting on a great show for us and we really appreciate it.

047:29:39 Cernan: Yes. Well, it's not a show. We just want to show you what we can see from out here. Not many people get a chance to get this far, and it really is a pretty exciting view.

047:29:48 Stafford: Yes. We also just wanted to thank all the people that helped make it possible for us to get here, too, Charlie.

047:29:57 Duke: Roger, We're passing it on, Tom, to the networks. This afternoon when we got the scheduled TV, we'd like you to do the water bag trick, the food separator stuff and - Let's see how that will look. We might be able to pick up something on the – on the live TV. Over.

047:30:15 Stafford: We'll show you a new law of physics: how the bubbles go to the bottom.

047:30:21 Duke: Okay. That's what we'd like.

047:30:23 Stafford: Roger.

047:30:45 Cernan: Forgot to tell you, Charlie. I got your picture walking to work this morning.

047:30:50 Duke: Oh, great. Walking to work?

047:30:57 Cernan: Yes. How come you were late?

047:31:00 Young: Charlie, it looks like Spain is mostly open today. I'm looking at it through the sextant. It really looks - It's beautiful.

047:31:06 Duke: Roger. Can you differentiate the...

047:31:09 Young: [Garble] Barcelona.

047:31:12 Duke: Excuse me. I was just going to ask you if you could differentiate the cities. Tell us about what you can see.

047:31:18 Young: Well, all you can make out is - It looks just like a map, a small map. And well, you can see, for, example, the Pyrenees. And you can see there, - maybe cloud cover down along the coast there, down on the Mediterranean coast. You can see, almost see, I think, Gibraltar.

047:31:42 Duke: Roger.

047:31:43 Young: And the Lisbon area over by Portugal seems to be clear. In France, Marseilles is open, and it looks like there's a little cloud cover in northern France. England is under the clouds.

047:31:56 Duke: Can you pick out any of the islands off of Greece, or say, Sardinia, or down around Italy, Capri, Sicily? Can you see those islands?

047:32:08 Young: They're pretty close to the terminator right now, and it's a little smoggier today than it was yesterday, but yesterday Crete was very clear, ll could see Cyprus; the Nile Delta is very clear right now. You can see the Nile; the Nile Valley really stands out, and, of course, the Sahara Desert is very clear, you can see geological features in the desert. It looks like Lake Chad down there in the middle of the – middle of Africa.

047:32:39 Duke: Roger. Start talking about geology and we will have [geologist-astronaut] Jack Schmitt in the room, in just a minute.

047:32:48 Young: I thought he was already there.

047:32:50 Duke: No, he's doing something over in the office today.

PAO: That's John Young giving his description of the Earth.

047:33:12 Young: That certainly is an interesting weather - weather patterns going across there. Now, I can see – I can see right now in Brazil, it stands out very clearly on the horizon. And Brazil is covered with those little thunderstorms that build in a tropical area. It just seems like each tree has its own separate thunderstorm down that way.

047:33:33 Duke: Roger.

047:33:35 Young: Boy, it's really a fantastic, just fantastic view. We can see right across the top off the world right now, and it sort of looks like, I don't know exactly how we are oriented, but it sort of looks like the North Pole is open today, but it isn't very much open. The whole northern part of the world is right under the worst cloud bank I've ever seen.

047:34:03 Duke: Roger. That thing has been there constantly almost since, it seems like, since you guys started showing us the pictures back. Do - Can you still see that strange-looking storm system up over the Bering - I guess it was just south of the Bering Straits out over Alaska there. Is that thing still there? It was a funny-looking swirl.

047:34:26 Young: We're right - The terminator runs down through Africa right now, Charlie, so we're starting to look at only about three-quarters of the world.

047:34:37 Duke: Roger.

047:34:42 Young: So that part of the world hasn't come around to us yet.

047:34:49 Duke: Roger.

047:35:03 Duke: 10, Houston. We're estimating High Gain loss at 37 [047:37:00]. We'd like you to - at High Gain loss, to return to Omni Bravo, and then we'll handle the Omnis from there. Over.

047:35:20 Cernan: Okay, Charlie.

047:35:58 Duke: 10 Houston. Bruce has got a little message here he cut out of the paper, and I'd like to read it up to Tom if you're ready.

047:36:08 Cernan: Stand by. Let us switch to Omni’s here in a second, Charlie.

047:36:10 Duke: Roger.

[Long comm break.]
PAO: This ia Apollo Control at 47 hours, 37 minutes. The TV can only be transmitted with the High Gain Antenna and there is a period in each of the revolutions that Apollo 10 makes for Passive Thermal Control and antenna loses lock with the ground antennas. It is at this period that they switch to the Omni antennas for voice communication, but television is not possible. Apollo 10's distance now 162,659 nautical miles [301,243 km], velocity 3,660 feet per second [1,116 metres per second]. We should be back in communication very shortly here. We will continue to stand by.

047:40:30 Cernan: Hello, Houston. You reading us?

047:40:32 Duke: Roger. Reading you five-by, now.

047:40:37 Cernan: Okay. I went to Omni Bravo, there, and left it there for about 2 minutes. I'm in Delta and when we lose signal strength, I'll give it back to you. I'll just go to Omni in Bravo, and let you do the switching.

047:40:49 Duke: Roger.

047:40:53 Cernan: Okay. You can read that message up, if you would, like.

047:40:56 Duke: Roger. It's from Weatherford, Oklahoma, dateline. It says two young Oklahoman’s had high hopes Sunday when they tried to send greetings to Apollo 10 Commander Thomas P. Stafford, an Oklahoma native. The two youngsters, about 10 years old were seen from a busy interstate highway by a passing motorist. They were standing on a hillside about 4 miles east of Stafford's hometown of Weatherford, holding aloft a printed sign with two small US flags attached to it. The sign said, "Hello, Tom." Did you see it?

047:41:29 Stafford: No. We were trying to, but couldn't quite make it there, Charlie. Tell them thanks a lot for the effort.

047:41:33 Duke: Roger...

047:41:34 Stafford: ...We appreciate it.

047:41:35 Duke: Roger.

047:44:00 Duke: 10, Houston. If you'll select Bravo on the Omnis, we've got the D command in and we'll just take over.

047:44:09 Cernan: Okay. You’ve got it.

047:44:11 Duke: Roger.

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