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Day 9 part 34: Awake on Splashdown day Journal Home Page Day 9 part 36: Homecoming

Apollo 10

Day 9 part 35: Entry Preparations

Corrected Transcript and Commentary Copyright © 2018 by David Woods, Robin Wheeler and Ian Roberts. All rights reserved.

Last update: 2018-01-19

187 hours GET view of Earth

The view of the Earth from Apollo 10 at 187:00:00.

Flight Plan

Mission audio

187:03:22 Stafford: Roger. Tell all the people around the world, Jack, and also in Houston, MCC, what a great job they've done, and we'll see them back there shortly. Over.

187:03:31 Lousma: Roger, Tom. Thank you and their congratulations to you and your crew. Over.

187:03:36 Stafford: Roger. We'll wait until we get onboard the carrier for that.

[Comm break.]

[Mission audio not available from this point until 187:11:08.

187:08:28 Cernan: Hello, Houston. This is 10. Do you want me to maintain High Gain for you until after the update?

187:08:41 Lousma: That is affirmative, 10. We prefer the High Gain for the update.

187:08:46 Cernan: OK.

187:09:17 Lousma: And, Apollo 10, Houston. I have some attitudes for P52.

187:09:23 Stafford: Stand by. We're still doing some stowing here. Go ahead and give me a rough one, Jack.

187:09:29 Lousma: Roger. The P52 - We have two attitudes. Probably the preferred is the one I'll read first and if you want another one, I'll give it to you.

187:09:40 Stafford: Go ahead.

187:09:41 Lousma: Roll, pitch, and yaw are all balls, and your stars are Menkent, number 30, Atria, number 34, and Nunki, number 37.

187:09:57 Stafford: Roger. Roll, pitch, and yaw all balls, stars 30, 34, and 37.

[Comm break.]

Mission audio

187:11:53 PAO: This is Apollo Control at 187 hours, 11 minutes Ground Elapsed Time. Apollo 10 now 36,136 nautical miles [66.924 km] out from Earth. Velocity continuing to build up; now 10,709 feet per second [3,264 m/s]. Estimated velocity at Entry Interface, or 400,000 feet [121,920 metres] above the surface; 36,314 feet per second [11,070 m/s]. Ignition time for midcourse correction number 7, 1 hour and 37 minutes away. Entry Interface 4 hours, 36 minutes away.

187:12:43 Stafford: Houston, Apollo 10. I’ll stay in this attitude until you give us the update, and then we'll go down to zero, zero, zero. Over.

187:12:50 Lousma: Roger. We copy, 10.

187:13:33 Lousma: Apollo 10, Houston. We're ready with your update. We've got a state vector and entry REFSMMAT and a midcourse 7 target load, and if you will go to Accept. In addition, we're not reading anything on the VHF yet, and we'd like you to ensure that the VHF is cranked up. Over.

[MCC-H are updating the CMC reference matrix (REFSMMAT) for the last time, in readiness for the entry.]

187:13:58 Stafford: OK, Houston. Apollo 10. We are in P00 and Accept. I've got the VHF warming up and we'll give you a call in just a minute. Over.

[The VHF/AM system will be needed for voice communication between the spacecraft and the recovery forces when they come out of communications blackout.]

187:14:07 Lousma: Roger, 10.

187:14:37 Stafford: Hello, Houston. This is Apollo 10 on VHF A Simplex. How do you read? Over.

187:14:44 Lousma: Roger. I hear you loud and clear, 10, on VHF A.

187:14:47 Stafford: Roger, Houston. This is 10 reading you loud and clear. Over.

187:14:58 Lousma: Belay my last, 10. I think I'm getting you on S-band. We'll check with the VHF people. [Long pause.]

187:15:54 Lousma: Apollo 10, Houston. Carnarvon reads you loud and clear on VHF.

187:16:00 Stafford: Roger, Houston. Apollo 10. I'm reading you about three-by-three on VHF. How me?

187:16:14 Lousma: Apollo 10, Houston. I'm reading you here on S-band, and we'll have to check with the sites to see how the VHF is coming in.

[Comm break.]

187:18:58 Lousma: Apollo 10, Houston. We're on VHF only. How do you read? Over.

187:19:10 Lousma: Apollo 10, Houston. How do you read on VHF? Over.

187:19:59 Lousma: Apollo 10, Houston. Back on the S-hand. Apparently you weren't reading us on VHF. We'll give you another VHF check in about a half an hour.

187:20:08 Cernan: OK, Jack. [Long pause.]

187:20:58 Lousma: Apollo 10, Houston. The uplink is complete. You can go to Block.

187:21:17 Stafford: OK.

187:21:52 Stafford: Houston, Apollo 10. I'll go ahead and pitch down to 000 when you have everything the [garble] as far as the uplink is complete and verified. I guess it is verified now. Over.

187:22:07 Lousma: Roger. The uplink is complete, Tom, and you're clear to the new attitude.

187:22:12 Stafford: Roger, 10. And, Houston, 10. This attitude of 000 will be a good one to torque to the new REFSMMAT? Over.

187:22:24 Lousma: That's affirmative, 10.

[Long comm break.]

Mission audio

187:31:56 Lousma: Apollo 10, Houston. We'd like you to go to wide beamwidth and High Gain Antenna and I have a maneuver PAD and an entry PAD for you.

187:32:06 Stafford: OK. We'll be with you in one second; I'm going to wide beamwidth right now.

187:32:18 Stafford: You're in wide, Houston, and we'll give you a call when we're ready to copy. We're still doing a few little chores here. Over.

187:32:19 Lousma: Roger.

Reformatted version of the entry checklist

[Long comm break.]

187:39:27 Cernan: Hello, Houston, Houston. This is Apollo 10. We're ready to copy your P30 and your entry update.

187:39:35 Lousma: Roger, 10. Here's the maneuver PAD. MCC 7, RCS/G&N: 25232, Noun 48 is NA. Noun 33 is 188:49:56.75; plus three balls 16, minus all balls, minus four balls 1; three balls, 129, three balls; apogee is NA, perigee is plus 0021.2; three balls 16, two balls 7, three balls 16; 40, 295.9, 38.3; 033, Uniform 159, Lima 12. The rest is NA; your set stars are Deneb, 43; Vega, 36; 067, 174, 343. Your ullage is a two-quad burn, use Bravo and Delta. Read back maneuver PAD; let me know when you're ready with the entry PAD. Over.

187:41:37 Cernan: OK. MCC 7, RCS G&N: 25232; 48's NA; 188:49:56.2 - .75, plus three balls 16, minus all balls, minus four balls 1. Roll is 000, 129, 000. Apogee is NA; perigee is plus 0021.2, three balls 16, two balls 7, three balls 16; 40, 295.9, 38.3; 033, Uniform 159, Lima 12; Deneb, 43 and Vega, 36; 067, 174, 343. Using two quads, Bravo and Delta. And I'd like to read Noun 33 back to you again. That's 188:49:56.75.

[The PAD is interpreted as follows:
Purpose: This PAD is for MCC-7, the only midcourse correction opportunity used during the trans-Earth coast.
Systems: The burn will be made using the SM RCS (Reaction Control System) under the control of the Guidance and Navigation system.
CSM Weight (Noun 47): 25,232 pounds (11,445 kg).
Pitch and yaw trim (Noun 48): As this is not an SPS maneuver the pitch and yaw trim angles for this engine are not required.
Time of ignition, TIG(Noun 33):188 hours, 49 minutes, 56.75 seconds.
Change in velocity (Noun 81), fps (m/s]:x, +1.6 (0.49); y, -0.0 (0.0); z, -0.1 (0.03). The change in velocity is resolved into three components expressed relative to the LVLH (Local Vertical/Local Horizontal).
Spacecraft attitude: Roll, 000°; Pitch, 129°; Yaw, 000°. The desired spacecraft attitude is measured relative to the alignment of the guidance platform.
HA, expected apogee of resulting orbit (Noun 44): Not applicable. The trajectory being modified has no sensible apogee, at least in terms of the computer.
HP, expected perigee of resulting orbit (Noun 44): 21.2 nautical miles [39.6 km). This will be their altitude at closest approach according to the trajectory resulting from this burn. As this altitude is within the Earth's atmosphere, re-entry will take place.
Delta-VT: 1.6 fps (0.49 m/s]. This is the total change in velocity the spacecraft would experience. (It is a vector sum of the three components given above.)
Burn duration or burn time: 7 seconds.
Delta-VC: 1.6 fps (0.49 m/s]. This value is entered into the Delta-V display of the EMS (Entry Monitor System) panel. They will watch this figure descend to zero as the RCS fires, giving them a confirmation of the burn's progress.
Sextant star: Star 40 (Altair) visible in sextant when shaft and trunnion angles are. 295.9° and 38.3° respectively. This is part of an attitude check.
Boresight star: Star 033 for maneuver attitude check using the COAS. The COAS viewing angles for the boresight star are 15.9° up, and 1.2° left.
GDC align stars: Stars to be used for GDC align purposes are Deneb (43) and Vega (36). The align angles are roll, 67°; pitch, 174°; yaw, 343°. This would be used in the event that the IMU could not be used for aligning the gyro assemblies. The spacecraft would be maneuvered so that the two stars could be viewed in the scanning telescope in a certain configuration. On achieving this, the spacecraft would be in a known attitude, the same one given in the PAD, allowing the GDC to be manually aligned.
Notes: As this is such a small Delta-V (velocity) correction, MCC-H are suggesting only using two of the four SM RCS quadrants to perform this maneuver, quads Bravo & Delta on opposite sides of the SM.]

187:43:04 Lousma: That's affirmative, 10. Entry PAD when you're ready.

187:43:11 Cernan: I’m ready, Jack.

187:43:13 Lousma: OK. The entry PAD is a Mid-Pac: three balls, 153, 001; 191:31:54; 268; minus 15.07, minus 164.67; 06.8, 36315, 6.52, 1204.1; 36395; 191:48:54; 00:28; Noun 69 is NA; D0 is 4.00; 028 - correction, 02:08; 00:18, 03:29, 08:17; 40, 262.1, 34.7; 033, Dog 089, Lima 22. Lift vector is Up. Comment: Use a nonexit pattern. Your horizon is dark at Entry Interface. Over.

187:45:29 Cernan: OK. Jack. Entry PAD. Area is Mid-Pac: 000, 153, 001; 191:31:54; 268; minus 15.07, minus 164.67; 068, 36315 6.52, minus 1204.1; 36395; 191:48:54; 00:28; Noun 69 is NA. Are you still with me?

187:46:33 Lousma: That's affirmative. Go ahead.

187:46:35 Cernan: DO is 4.00; 02:08; 00:18, 03:29, 08:17; 40, 262.1, 34.7; 033, Delta 089 and Lima 22. The lift vector is Up; using a nonexit pattern and the horizon is dark at Entry Interface.

187:47:19 Lousma: Roger, 10. I have a late correction at the bottom. SPA is Dog 080, now. Over.

187:47:29 Cernan: Roger. SPA is 080.

187:47:37 Lousma: And, 10. We'd like you to read the range to go back, please.

187:47:47 Cernan: OK. The range to go is 1204.1.

187:47:54 Lousma: Roger. We copy. And that's affirmative.

[The crew have a form available to fill out with the Entry PAD.]

Form for the Lunar Entry PAD

Form for copying down the Lunar Entry PAD.

[The PAD is interpreted as follows:
Purpose: Entry.
Landing target:The landing target is in the Mid-Pacific.
IMU gimbal angles required for trim at 0.05g: Roll, 0°; pitch, 153°; yaw, 1°.
Time of the horizon check: 191 hours, 31 minutes, 54 seconds GET.
Spacecraft pitch at horizon check: 268°. This is 17 minutes before time of entry.
Splashdown point (Noun 61): 15.07° north latitude, 164.67° west longitude.
Maximum number of gs during entry: 6.8g.
Velocity at Entry Interface (400,000 feet altitude, Noun 60): 36,315 feet/second (11,070 m/s).
Entry flight path angle at Entry Interface: 6.52°.
Range to go (RTGO) to splashdown point from 0.05g event: 1,204.1 nautical miles (2,230.0 km).
Predicted inertial velocity (VI0) at 0.05g event:36,395 feet per second (11,093 m/s).
Time of Entry Interface: 191 hours, 48 minutes, 54 seconds GET.
Time from Entry Interface (400k feet (121,920 metres) to 0.05g event: 0:28 (seconds).
As this is a non exit entry, Noun 69 is not applicable.
Planned drag level (D0) (deceleration) during the constant g phase: 4.00g.
Time from Entry Interface until their velocity slows sufficiently to allow a circular orbit around the Earth: 2:08. The practical implication of this is that this is the "capture point" where the CM cannot exit on an orbit around Earth. It is bound to reach the surface on this pass.
Time from Entry Interface that the communications blackout begins: 0:18.
Time from Entry Interface that the communications blackout ends: 3:29.
Time from Entry Interface that the drogue parachutes will deploy: 8:17.
Sextant star: 40 (Altair)
Sextant shaft angle at Entry Interface minus 2 minutes: 262.1°.
Sextant trunnion angle at Entry Interface minus 2 minutes: 34.7°.
Boresight star:Star 033 for maneuver attitude check using the COAS. The COAS viewing angles for the boresight star are 8.0° down, and 2.2° left.
Lift vector at Entry Interface: Up.
Comments in addition to the PAD: They should use a non exit EMS scroll pattern, and the horizon will be dark at the time of Entry Interface as they are travelling towards the sunrise terminator.]

[Long comm break.]

Mission audio

187:51:XX PAO: This is Apollo Control. To translate some of the exchange of numbers between the spacecraft and the ground; they were passed up a maneuver PAD for midcourse correction burn number 7; will be with the RCS thrusters. At 188 hours, 49 minutes, 56.75 seconds, 1.6 foot per second [0.49 m/s] velocity change, burn time of 7 seconds. The additional - the other PAD for the entry numbers to the Mid Pacific prime recovery line, nominally along 165 west longitude, showing target point of 15.07 south latitude, 164.67 west longitude. Maximum gs expected, 6.8; velocity at 400,000 feet [121,920 metres] or Entry Interface, 36,315 feet per second (11,070 m/s]; flight path angle at 400,000 feet [121,920 metres], 6.52 degrees. The range to go at the time the Entry Monitor System is activated, 1,204.1 nautical miles [2,230.0 km]. Velocity at the time the Entry Monitor System is activated and the crew begins reading the onboard displays of range to go, steering commands and so on, 36,395 feet per second (11,093 m/s]. Begin blackout, 18 seconds after Entry Interface. End black out; 3 minutes, 29 seconds after Entry Interface. Drogue deploy; 8 minutes, 17 seconds after Entry Interface. They were also informed that the horizon would be dark at Entry Interface. Now 187 hours, 52 minutes Ground Elapsed Time. Showing 57 minutes, 40 seconds, mark, to ignition of midcourse correction burn number 7; 3 hours, 56 minutes, 28 seconds to Entry Interface. Distance now 31,956 nautical miles [59,182 km] out from Earth; speed continuing to increase to now reading 11,336 feet per second [3,455 m/s]. Continuing to monitor air to ground circuit for continuing conversation of Apollo 10 crew, with spacecraft communicator Jack Lousma here in Mission Control.

188 hours GET view of Earth

The view of the Earth from Apollo 10 at 188:00:00.

Flight Plan

Mission audio

188:00:03 Lousma: Apollo 10, Houston. We know the set - the DAP is now set up for four jets, and we think we ought to have two jets. That'd be B and D. Over.

[A two-jet ullage was specified in the MCC-7 PAD.]

188:00:15 Stafford: OK. Roger. You want - Since it's only a couple of feet per second here and everything, we've got plenty of fuel, but we’ll go ahead and use two jets. Our checklist calls for four. Over

188:00:31 Lousma: Roger, 10.

[Comm break.]

188:04:59 Young: Houston, this is 10. We're going into the cold soak in our checklist, there.

188:05:06 Lousma: Roger, 10. Copy.

[Long comm break.]

188:11:35 Cernan: Houston, this is 10. What’s your feeling about putting fuel cell 1 on for the burn?

188:11:40 Lousma: Stand by one.

188:11:59 Lousma: Apollo 10, Houston. We don't need fuel cell 1 for the burn and don't intend to use it for the burn. Over.

188:12:07 Cernan: OK.

[Long comm break.]

Mission audio

188:19:08 Stafford: Houston, Apollo 10. We're starting through our P30 series now. Over.

[The prethrusting program, Program 30 (P30 - External Delta-V) is run to enter the basic parameters such as the time of ignition and change in velocity, which was provided in the MCC-7 PAD.]

188:19:14 Lousma: Roger, 10.

[Comm break.]

188:22:24 Lousma: Apollo 10, Houston. We suspect that your suit circuit heat exchanger may be in the Bypass position and - well, for comfort, it ought to be on now, and go to Bypass at EI minus 50. Over.

188:22:37 Young: Roger.

[Very long comm break.]

Mission audio

188:33:46 Lousma: Apollo 10, Houston. When it's convenient, we'd like to get a GET time hack with you.

188:33:53 Stafford: It's convenient. Over.

188:33:56 Lousma: Roger. Go ahead and give us a time and we'll set our clocks.

188:34:04 Stafford: OK. It's 188:34, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15. Over.

188:34:17 Lousma: OK. Thank you very much. We're right on.

188:34:20 Young: That's computer time and GET time, and our mission time is right on.

188:34:25 Lousma: Roger. We're following right along with you.

[Comm break.]

188:37:39 Stafford: Houston, Apollo 10.

188:37:43 Lousma: Go ahead, 10.

188:37:46 Stafford: OK. We're going to go ahead and call up P41.

[Program 41 (P41 - RCS Thrusting) is now selected. P41 and uses the data computed by P30 to calculate the steering commands, maneuver the spacecraft to the burn attitude and control the RCS burn.]

188:37:49 Lousma: OK. We'll be watching you.

188:39:47 PAO: This is Apollo Control, 188 hours, 39 minutes Ground Elapsed Time, coming up on 10 mark to the burn, Mark, 10 minutes to ignition of midcourse correction burn number 7, air-to-ground still live.

[Comm break.]

188:41:57 Stafford: Houston, Apollo 10. Would you give us a hack at 5 minutes prior to the maneuver just so we can recheck our event timer? Over.

188:42:06 Lousma: Roger. Understand you want a time hack just prior to the burn. Is that affirmative?

188:42:11 Stafford: Give us one at 5 minutes. This event timer occasionally has been jumping numbers. Over.

188:42:16 Lousma: Roger. We'll give you a hack at 5 minutes. That'll be about a minute and a half yet.

188:42:56 Young: OK, Houston. We're showing 7 minutes.

188:42:58 Young: Mark.

188:42:59 Young: How's that sound?

188:43:00 Lousma: Yes. We're showing the same. That's confirmed, 7 minutes.

188:43:03 Cernan: OK.

[Comm break.]

Mission audio

188:47:06 Stafford: OK. We're proceeding here for the final trim.

188:47:12 Lousma: Roger, 10.

188:47:38 Young: Boy, this is absolutely fantastic. Come all the way back to the Moon and do this kind of midcourse.

188:47:47 Lousma: Yes. That's pretty good shooting, isn't it?

188:47:29 Young: Man, I mean to tell you.

188:47:55 Stafford: Tell Christopher C. and company looks like they have a pretty good rifle scope there to shoot us back in this target. Over.

[Stafford is referring to the then Director of Flight Operations, Christopher C. Kraft jr.]

188:48:02 Lousma: Roger. I guess all that mathematics really works after all.

188:48:08 Stafford: Roger.

188:48:51 Lousma: Apollo 10, Houston. We have a few configuration items we'd like to point out. Right...

188:48:58 Stafford: OK. We'll wait.

188:49:00 Lousma: Rotational hand controller power, Direct; BMAGS, Att 1, Rate 2. Over.

[MCC-H are reminding the crew that switches for the rotational hand controller Direct configuration, on panel 1, should both be set to buses MNA & MNB. When the rotational hand controller is deflected 11 degrees, in this mode, power will be applied to the direct coils of the appropriate RCS engines, and the auto coils will be disable for this axis (or axes). This permits the crew to directly, manually alter the spacecraft's attitude.

They also being reminded to set the BMAG mode for each of the three axes to Att 1, Rate 2. This BMAG setting allows the gyro assembly 2 to provide rate signals for control and display, plus for the GDC update, and allows gyro assembly 1 to provide attitude error signals for control and display.]

188:49:07 Young: Roger.

188:49:24 PAO: This is Apollo Control. Mark, 30 seconds to ignition.

188:49:58 Stafford: We're burning.

188:50:26 Stafford: OK. How we are on our residuals? You can read them? 0, minus 1, minus 1, and a Proceed.

188:50:33 Lousma: Roger. We copy.

188:51:21 PAO: This is Apollo Control. Midcourse correction burn number 7 scheduled for 7 seconds duration, was actually burned out at 6.6 seconds.

[Comm break.]

188:53:02 Stafford: Houston, Apollo 10. It's starting to get real cool in here. We'd like to go Bypass on the suit circuit heat exchanger. Over.

[Placing the Suit Circuit Heat Exch switch panel 2 in the Bypass position, prevents the flow of water-glycol through the suit heat exchanger, allowing the suit circuit temperature to increase.]

188:53:18 Stafford: And we can turn it on if it gets warm again. Over.

188:53:24 Lousma: Roger, 10. Go ahead.

188:53:28 Stafford: Bypass.

188:54:12 Cernan: Hello, Houston. This is 10. Could you give me a short count, and I'll cut off my S-band and see whether I can pick you up on VHF?

188:54:21 Lousma: Stand by one, please.

188:55:04 Lousma: Apollo 10, Houston. We'll try a VHF voice check as soon as we get the sites configured and you can go to left antenna. Over.

188:55:16 Cernan: OK. Thank you, Jack.

188:56:47 Lousma: Apollo 10, Houston. Set up your VHF and S-band turned down. We're going to try the VHF check in a minute.

188:57:08 Lousma: Hello, Apollo 10. Houston on VHF through Guam. How do you copy? Over.

188:57:20 Lousma: Apollo 10, Houston. How do you read? Over.

188:58:11 Lousma: Apollo 10, we're back up on S-band. We weren't able to read you on VHF. Over.

188:58:18 Young: Roger. We heard some kind of transmissions there in the background, but we never gave you a call on VHF. Over.

188:58:27 Lousma: Roger. I asked for a radio check on VHF. Apparently we're not quite in range yet.

188.59:24 PAO: This is Apollo Control. Apollo 10 now 24,469 nautical miles [45,317 km] out from Earth; velocity now 12,794 feet per second [3.900 m/s]. Still monitoring air to ground, live.

189 hours GET view of Earth

The view of the Earth from Apollo 10 at 189:00:00.

189:00:06 Lousma: Apollo 10, Houston. All sites are monitoring VHF downlink. When you're ready, make a transmission and they'll see if we can pick you up.

189:00:15 Stafford: Roger, Houston. This is Apollo 10 transmitting on VHF on the short count. 5, 4, 3, 2, 1. How do you read? Over.

Mission audio

189:01:57 Lousma: Apollo 10, Houston. Sites apparently aren't reading you yet on VHF. We recommend that you transmit simultaneous S-band and VHF; and, when the sites can read VHF, why, they'll let us know, and we'll conduct the radio check. Over.

189:02:10 Young: Roger. That's what we're doing. Over.

189:02:19 Stafford: OK, Houston. Apollo 10. We're all squared away and way ahead on the checklist. The next thing we're waiting for is just to read out the Command Module RCS temps and service the primary Evap and the logic check coming up. Over.

189:02:35 Lousma: Roger. And there's no significant change in the weather in the landing area. The altimeter is 29.88, or plus 38 feet, and we have a splashdown computed time of 192:03, and sunrise will be 25 minutes later. Over.

189:02:58 Stafford: Roger 192:03, sunrise 25 minutes later. Thank you.

189:03:04 Lousma: Roger. And you copy altimeter 29.88.

189:03:08 Stafford: Roger.

[The Command Module has an altimeter, similar to those found on aircraft that rely on the measurement of air pressure to determine altitude. It is sited just above the EMS panel. In order for an aircraft altimeter to be accurate, compensation must be made for the sea level air pressure which, at the time, was conventionally stated in terms of inches of mercury (the height of a column of mercury whose weight would balance the weight of the column of air creating the air pressure at that point); in this case 29.88 inches. However, as John will point out, unlike an aircraft altimeter, there is no provision for setting the sea level pressure on the Apollo version.

189:03:13 Young: Hey, Jack, we don't have any place to set the altimeter. But thanks for the plus 38 feet.

189:03:19 Lousma: Roger. Plus 38.

189:03:37 Lousma: And, 10, we're ready for your RCS temps when you're ready to read them down.

189:04:37 Cernan: Houston, here's our readings: 5-Charlie is 5.0; 5-Delta is 4.8; 6-Alpha is 5.1; 6-Bravo is 5.1; 6-Charlie is 4.2; 6-Delta is 4.9.

[These readings from the system test meter on panel 101 are checking the CM RCS temperatures. So long as they all read above 3.9 VDC, no pre-heating will be required.

These readings translate to:
5C CM RCS system B - pitch engine oxidizer valve 5.0 VDC = 50°F
5D CM RCS system B + yaw engine oxidizer valve 4.8 VDC = 46°F
6A CM RCS system A counter clockwise roll engine oxidizer valve 5.1 VDC = 52°F
6B CM RCS system A - pitch engine oxidizer valve 5.1 VDC = 52°F
6C CM RCS system A - yaw engine oxidizer valve 4.2 VDC = 34°F
6D CM RCS system B clockwise roll engine oxidizer valve 4.9 VDC = 48°F]

189:05:24 Lousma: Roger, 10. We copied the temperatures. Thank you.

[Comm break.]

189:07:12 Young: Houston, at 45 minutes to EI - to RRT time – Could you give us a time hack? Over.

189:07:20 Lousma: Roger. You want a time hack at 45 minutes to EI.

189:07:24 Young: That's affirmative.

189:07:25 Lousma: And your computer landing time precisely is now 192:03:57.

189:07:47 Young: Houston, we're going back On with the suit circuit heat exchangers. It doesn't take very long.

[Placing the Suit Circuit Heat Exch switch on panel 2 in the Bypass position, has had the desired effect, the crew are more comfortable, so Young is returning it to the Flow position to allow the suit circuit heat exchange to cool the suit gases and remove moisture in the circuit.]

189:07:53 Lousma: Roger to On.

189:08:39 Lousma: Apollo 10, Houston. Late correction on your landing time is 192:02:57.

189:08:52 Young: [Laughter.] Roger. 192:02:57.

189:08:59 Lousma: Buddy, you're going to get there. It doesn't really matter does it?

189:09:08 Young: Yes. We'll get back.

189:09:09 Lousma: Yes. We could put you in a holding pattern for a minute there, maybe.

189:09:18 Young: As long as our RET times are OK, we're in good shape.

189:09:28 Stafford: Houston, Apollo 10. Over.

189:09:30 Lousma: Go ahead.

189:09:32 Stafford: Roger. Wish you would relay on to Captain Cruse, the skipper of the Princeton, that at the time there, at 192:03, we expect to be right on top of the aim point and hope this big ship is close by. Over.

189:09:47 Lousma: Roger. We'll pass the word on, and you just holler "Meat Ball" when you see it.

189:09:53 Stafford: Will do.

[Comm break.]

[The 'meat ball' is an optical system used on aircraft carriers to indicate to an incoming pilot that they were on the correct glide slope as they approached the carrier's deck.]

189:10:38 PAO: This is Apollo Control. To recap that last exchange, predicted touchdown time, in Ground Elapsed Time 192 hours, 2 minutes, 57 seconds. Back to air to ground.

189:13:08 Young: OK, Houston. Our data up here shows no preheat.

189:13:19 Lousma: Roger. We confirm that, 10.

[As the temperatures of the CM RCS are all above 28°F, no pre-heat is required to condition them for use. Therefore as no additional electrical power will be required for the pre-heat, it will not be necessary to bring the limping fuel cell 1 back on line to supplement the two healthy fuel cells.]

[Long comm break.]

Mission audio

189:18:53 PAO: This is Apollo Control. Mark; 2 hours, 30 minutes to Entry Interface, or sensible atmosphere at 400,000 feet (121,920 metres] above the surface. Apollo 10 now 22,150 nautical miles [41,022 km] out from Earth. Velocity beginning to increase - air to ground here.

189:19:11 Cernan: Houston, this is 10. The glycol Evap water-flow valve will come on in two zero minutes.

189:19:20 Lousma: Roger. Two zero minutes.

189:19:22 Cernan: I'll leave it On for 3; then to Auto. Is that correct?

189:19:33 Lousma: That's affirmative, 10.

189:19:36 Cernan: OK. Thank you.

189:19:42 PAO: Velocity now 13,399 feet per second [4,084 m/s], beginning to build up as they get back closer into Earth - air to ground still live.

189:21:25 Lousma: Apollo 10, Houston. We would like to have all heaters and fans Off in the Cryo tanks. Over.

189:21:33 Young: Roger. Heaters and fans going off in the Cryo tanks.

189:21:44 Young: They're all Off.

189:21:46 Lousma: Roger.

189:23:05 Cernan: Houston, the Evap servicing is complete, and for the record, of course, we had been there before, but I had gone to Manual Increase again on the valve.

[In an attempt to ensure the primary Glycol Evap does not dry out as it did at the beginning of the mission, Cernan, during the its servicing, selected on panel 2, Steam Press Man which permits manual operational of the steam pressure valve actuator, and Incr which is operated momentarily to increase the steam pressure.]

189:23:15 Lousma: Roger. We copy, and Manual Increase.

189:23:20 Cernan: And I know I've got the water flow in Auto.

[Cernan also has the H2O Flow switch on panel 2 in the Auto position to apply power to the steam press/wetness control unit and allows automatic regulation of the flow of water to the water-glycol evaporator.]

189:23:24 Lousma: Roger, Gene.

189:23:35 Cernan: Houston, this is 10.

189:23:38 Lousma: Go ahead, 10.

189:23:47 Lousma: Apollo 10. Houston. Go ahead.

189:23:50 Cernan: Roger. We're requesting an in-route descent commencing 1200 Out, and we'd also like expeditious handling, CCA down near the Princeton. We'll be making a vertical descent from about 24,000 (ft, 7,300 metres]. And request No Go-around this pass.

189:24:08 Lousma: Roger. Report crossing 25 miles (40 km) at 6,000 [ft, 1,800 metres]. Over.

189:24:18 Young: How about that? Houston approach hasn't changed a bit.

189:24:23 Stafford: We hope on this one, Houston approach at 6,000 [ft, 1,800 metres] will be within about a half to a quarter of a mile [0.8 to 0.4 km]. Over.

189:24:31 Lousma: Roger. You can write your deviation up when you're on the ground.

[The crew are jovially using aeronautical terminology to request a priority approach to the splashdown point, with no go-around option as they are coming in ready or not, vertically.]

189:24:36 Stafford: Roger.

[Very long comm break.]

189:38:27 Cernan: Hello, Houston. 10. What's our range to Mother Earth?

189:38:34 Lousma: OK, 10. We're reading 19,660 [nautical miles, 36,410 km] at this time.

189:38:42 Cernan: OK. And how fast we going?

189:38:45 Lousma: You're coming in about 14,100 feet per second [4,300 m/s] right now. You're really picking it up.

189:38:52 Cernan: Thank you, sir.

189:39:19 Young: It's that last 10,000 miles (18,520 km) that's more interesting anyway.

189:40:11 Stafford: Hello, Houston. Apollo 10. Over.

189:40:13 Lousma: Go ahead, 10.

189:40:25 Lousma: Apollo 10, Houston. Go ahead.

189:40:28 Stafford: Roger, Houston. We still have lots of propellant in our primary propellant tanks, but we wanted to know, for the Service Module jettison, if you want us to open the secondary propellants. Over.

[The SM RCS will be automatically fire. The -X SM RCS engines will fire to assist separation and cause the SM to tumble during its atmospheric entry, which will speed up its destruction. The RCS will fire until propellant depletion, so MCC-H are not concerned with the quantity remaining.]

189:40:39 Lousma: Stand by one, please.

189:40:41 Young: Roger.

189:40:54 Lousma: Apollo 10, Houston. Proceed as per the checklist. Over.

189:40:59 Stafford: Roger. As per checklist.

[Long comm break.]

Mission audio

189:47:57 Young: OK, Houston. We're ready for the logic sequence check now.

189:48:07 Lousma: Stand by one, Apollo 10.

189:48:18 Lousma: OK, Apollo 10. We're ready to go with the check. Over.

189:48:43 Young: OK. The ELS logic is coming on. ELS going to Auto. SECS logic is coming on. OK. We're all set up.

189:49:05 Lousma: Roger. 10. Stand by.

189:49:14 Lousma: OK. Apollo 10, Houston. We'll give you a Go for Pyro Arm.

189:49:21 Young: Roger. SECS logic coming back off.

[The Sequential Events Control Subsystem logic circuit is used to provide part of the serial protection of the circuits that command pyrotechnic ordnance devices that initiate the several sequential events, such as CM-SM Sep. The Seq Event Control System switches, 1 & 2, are located on panel 8. When placed in the Logic position, either switch energizes the relays that connect the Main Event Sequence Controller logic circuits to battery buses A & B.]

[Comm break.]

189:53:53 Young: Houston, this is 10. We completed the sextant star check and Altair was within about 6 minutes of being right in the middle of the optics.

[The sextant check is performed to give additional confidence that the spacecraft attitude is correct.]

189:54:06 Lousma: Roger We copy, 10.

[Long comm break.]

187 hours GET view of Earth

The view of the Earth from Apollo 10 at 190:00:00.

Flight Plan

190:03:39 Cernan: Hello, Houston. This is 10.

190:03:41 Lousma: Go ahead, 10.

190:03:44 Cernan: Do you want to remain High Gain here until just before Sep?

190:03:50 Lousma: Stand by one.

190:04:23 Lousma: Apollo 10, Houston. Let's stay in High Gain until Sep and then go to Sep C. Over.

190:04:30 Cernan: OK. That's Sep Charlie; is that right, Jack?

190:04:35 Lousma: Sep Charlie at Sep. Let's stay in High Gain until that time. Over.

190:04:39 Cernan: OK. Fine. Thank you.

[Long comm break.]

Mission audio

190:11:24 Lousma: I think you're lucky there in a Noun 05.

[Young is performing a P52 IMU realignment, option 3, realigning it to the current REFSMMAT. The Noun 05 that Lousma is referring to is the star angle difference displayed on the DSKY as xxx.xx degrees when two stars are sequentially sighted through the sextant, when checking the realignment accuracy. The computer knows the angle between the two stars, thanks to into internal table of their positions. It also knows the angle between John's two sightings, and compares them. a reading of zero means the two angles match and there is no difference.]

190:11:30 Stafford: Wait until you see the next one.

190:13:29 Stafford: How about that, Jack? Over.

190:13:33 Lind: That's not bad for a young fellow.

190:13:37 Lousma: OK. You proved a point.

190:13:40 Stafford: I told you. Wait until the next one.

190:13:44 Lind: You're just a show off; that's all.

190:13:49 Stafford: How about that, Don?

190:13:52 Lind: Those ain't bad.

190:13:53 Stafford: José can work with those optics.

190:13:57 Lind: Who's doing that, you or José?

190:14:01 Stafford: No. That's José; I’m just narrating here.

190:14:03 Lind: OK.

[Comm break.]

190:16:24 Lousma: Apollo 10, Houston. Our tracking data now shows you right in the middle of the fairway with a 6.53-degree entry angle. Over.

190:16:34 Stafford: Roger. Right in the middle of the corridor with 6.53. Roger.

[Long comm break.]

Mission audio

190:23:32 Stafford: Houston, we checked Noun 61 and it looks loaded correctly now.

190:23:40 Lousma: Roger, 10. We're checking it.

190:23:40 Young: Roger. Our sextant - our alignment check sextant star on Nunki - the Auto optics put the star within the center of the reticle.

190:23:58 Lousma: Roger. Copy, John.

190:25:10 Lousma: Hello, 10. Noun 61 looks good to us.

[The Noun 61 that Lousma is referring to is the display of the input splashdown latitude and longitude, as derived from the Entry PAD, along with the appropriate Roll Attitude Code., + 1 for heads up / lift vector down, or in this case, - 1 for heads down / lift vector up. MCC-H are happy that is data has been entered correctly. This is the first part of the configuration of Program 61, the entry preparation program, which starts the navigation, checks the IMU alignment. and provide Entry Monitor System initialization data.]

190:25:15 Stafford: Alrighty.

190:25:16 Young: Roger.

[Comm break.]

Evaporator controls, Panel 2

EMS panel.

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

[The EMS is tested in readiness for the entry. The test steps are listed below:
EMS FUNC - Off
circuit breaker EMS (2) - close
EMS Mode - STBY
EMS FUNC - EMS TEST 1 (wait 5 sec)
EMS Mode - Normal (wait 10 sec)
Check indicator lights - off
Range indicator - 0.0
Slew hair line over notch
In self-test pattern
EMS FUNC - EMS TEST 2 (wait 10 sec)
.05G light - on (all others out)
EMS FUNC - EMS TEST 3
.05G light - on
RSI Lower light - on (10 sec later)
Set Range counter to 58 nm±0.0
EMS FUNC - EMS TEST 4
.05G light - on (all others out)
G-V trace within pattern to lower right corner @9G
Range indicator counts down to 0±0.2
EMS FUNC - EMS TEST 5
.05G light - on
RSI upper light - on (10 sec later)
Range indicator - 0.0
Scribe traces vertical line 9g to 0.22±0.1
ALIGN SCROll TO Entry PATTERN (on 37K ft sec line)
EMS FUNC - RNG SET
G-V scroll assembly traces vertical line 0.22g to 0±0.1
EMS Mode - STBY

The 5 EMS tests are carried out to ensure the EMS is ready and configured for the upcoming entry.

EMS test 1 Tests the lower trip point of the 0.05 G - threshold comparator and enables slewing of the scroll.

EMS test 2 Tests the high trip point of the 0.05 G - threshold comparator.

EMS test 3 Test the lower trip point of the corridor verification comparator and enables slewing of the Delta-V/Range display for EMS test 4 operations.

EMS test 4 Tests the range-to-go integrator circuits, G servo circuits, G - V plotter and range-to-go circuits.

EMS test 5 Tests the high trip point of corridor verification comparator and enables slewing of the scroll.]

190:28:42 Young: OK, Houston. EMS tests passed successfully.

190:28:48 Lousma: Roger. EMS. Thank you.

190:29:30 Young: OK. Houston, as I was driving the scroll down to - down to the pattern, the thing stopped scribing.

190:29:41 Lousma: Roger. She stopped scribing.

190:29:44 Lind: Say again, John.

190:29:47 Young: I say, the EMS stopped scribing as I was driving it down to the test pattern to set it up on the exit range.

[Following the EMS tests the scribe head is positioned at the 37K fps (11,270 m/s] mark on the next non-exit scroll pattern in the EMS display window. The formulation of the emulsion on the scroll film had recently been changed and this may have caused the emulsion to harden to much, so for Apollo 13 onwards the emulsion reverted to the original formulation.]

190:29:57 Lind: Oh, you mean driving it down to 37 K?

190:30:01 Young: Yes. I can't get this one. I say it stopped scribing.

190:30:08 Lind: You say the needle's not scraping, or it's not driving in this tape?

190:30:14 Young: It's not - the tape is driving, but the needle is not leaving any mark.

190:30:18 Lind: Understand.

190:30:21 Young: I believe I’ll go ahead and run it on down here anyway.

190:30:26 Lousma: Roger.

190:30:27 Lind: You might as well.

190:30:32 Young: Get some gs on it; it might work OK.

190:30:36 Lind: It's worth a try.

190:31:18 Young: OK. We're set up at 37 K.

190:31:22 Lousma: Roger. Maybe it'll come back in.

190:31:24 Young: On a non exit pattern. [Long pause.]

190:32:01 Cernan: Houston, this is 10. Have I got a Go to activate the primary Evaps?

190:32:07 Lousma: Standby one.

190:32:13 Lousma: 10, Houston. Activate the primary Evaps.

190:32:17 Cernan: OK. Here goes.

[Comm break.]

Mission audio

190:37:56 Young: OK. Houston, we are going to maneuver to the Sep attitude now.

190:38:00 Lousma: Roger. Maneuvering to Sep attitude.

[The spacecraft is yawed 45° left, out-of-plane, from the pre-entry attitude to the SM Sep attitude.]

[Comm break.]

190:40:19 Lousma: Apollo 10, Houston. John, if you haven't already tried it, you might, on that EMS scroll, try running the tape back a half inch backwards and back and forth between the 37K line, and if that doesn't work, why, you can try the next pattern, and maybe this will break up that emulsion a little bit.

190:40:56 Young: Roger. Understand. Run the scroll back and forth between where and where? Over.

190:41:02 Lousma: Make sure you run it backwards first, backwards no more than half an inch, and then forwards no more than the 37K line. Over.

190:41:11 Young: Roger.

190:41:44 Young: By golly, that fixed it. Good thought there. What I did was I had it on range set, I went back to test 5. Does that mean that I have to go all the way through the EMS counterclockwise anymore, or if I go to range set, will it still be initialized at 37K. Over.

190:42:09 Lousma: Roger, John. Say again how far back you went please.

190:42:12 Young: About three-eighths of an inch.

190:42:21 Lousma: Stand by one. [Long Pause.]

190:42:55 Cernan: Hello. Houston. This is 10.

190:42:57 Lousma: Go ahead.

190:42:59 Cernan: Roger. We're getting a lot of noise on the High Gain in this Sep attitude. How about me going to Sep at this time?

190:43:05 Lousma: Stand by.

190:43:15 Lousma: Apollo 10, Houston. Let's go to Sep Charlie by the checklist. Over.

190:43:33 Cernan: OK. We'll hold off on it, then; but it's awful noisy up here.

[Maneuvering the spacecraft to the Sep attitude has compromised the quality of the High Gain Antenna signal. The crew want to switch to the CM mounted omnidirectional antenna that they will use post Sep. At this range the high bit rate communications can be maintained via the CM omni antenna. MCC-H are instructing the crew to use Omni Charlie which is located on the CM external skin approximately behind window 2.]

CM Omni antenna locations

CM Omni antenna location.

190:43:50 Stafford: OK. Houston, we're going back to the initial Entry Interface attitude. This noise is about to drive us wild up here on that High Gain.

190:43:58 Lousma: Roger, 10. It's OK to go Sep Charlie, now, if you'd rather.

190:44:04 Cernan: OK. We can go there now, huh? OK. Because we're a little bit ahead of the checklist in going into this attitude. That's why I asked. OK. We'll go to Sep Charlie at this time.

190:44:11 Lousma: Roger.

190:44:59 Lousma: Apollo 10, Houston. It's not clear to us exactly what you did with the EMS. Will you describe it one more time so we can give you an answer? Over.

190:45:07 Young: Roger. I was on Range Set when you said wiggle it back and forth, so I went back to test 5 and brought it back approximately three-eighths of an inch toward 38K, and it started scribing. So I quit and went back to 37, and I'm now on test 5.

190:45:26 Lousma: Roger.

190:45:27 Young: My question is...

190:45:32 Lousma: Go ahead with your question.

190:45:35 Young: Do I have to go through another scroll pattern or go clean through the EMS test to get it reset at 37K?

190:45:43 Lousma: Roger. We'll get an answer for you in just a minute.

190:45:49 Young: I think the answer is no.

190:45:58 Lousma: Apollo 10, while we're coming up with that answer, we're ready to uplink a state vector. Can we have the computer? Over.

190:46:13 Stafford: We're in CMC and Accept.

[Final P27 update.]

190:46:15 Lousma: Roger. Thank you.

190:47:30 Lousma: Apollo 10, Houston. We're a little delayed on our uplink. It'll be up momentarily. It's coming now.

190:48:50 PAO: This is Apollo Control. Mark 1 minute to Entry Interface at which point the Apollo 10 will come back into the, effectively, the Earth's atmosphere at 400,000 feet [121,920 metres].

190:49:05 Lousma: Apollo 10, Houston. I have an update to your entry PAD. There are only five numbers that are different than the last PAD. Over.

190:49:15 Cernan: OK, Jack. Take them one at a time, will you? And let me confirm them would you?

190:49:26 Lousma: OK. Our gamma at 400K is now 6.54. Over.

190:49:37 Cernan: 6.54 gamma at 400K.

[When they reach Entry Interface (400,000 feet or 121.92 km) then their flight path will for an angle with the local horizontal at that point of 6.54°.]

190:49:42 Lousma: That's affirmative, and our RET at 0.05g is 00:27.

190:49:54 Cernan: 00:27 at 4 - 0.05g, RET.

[The point when they reach an aerodynamic deceleration of 0.05g is expected to occur 27 seconds after Entry Interface.]

190:50:07 Lousma: OK. That's affirmative. And the next three numbers are in the blackout block. Begin blackout at 00:17, end at 03:28, and drogues at 08:16, Over.

190:50:32 Cernan: OK. I got begin blackout at 00:17, and blackout at 3:28, and drogues at 8:16.

[Blackout will begin at 17 seconds and end at 3 minutes, 28 seconds. The drogues should deploy at 8 minutes and seconds, all after the 400K point.]

190:50:43 Lousma: That's affirmative.

190:50:46 Cernan: Thank you.

190:50:51 PAO: This is Apollo Control. To correct statement earlier in reading the clock it's now 57 minutes to Entry Interface, instead of 1 minute.

190:50:56 Stafford: Houston, Apollo 10. Are you finished with the uplink? Over.

190:51:01 Lousma: Apollo 10, we're finished with the uplink.

190:51:04 Stafford: Roger. Back to Block.

190:51:22 Stafford: Shows we got a 22.2-mile vacuum perigee. It looks good.

[Keying Verb 82 Enter starts Routine 30 which can be used to display current orbital parameters. A flashing Verb 16, Noun 44 displays the following parameters:

R1-Apogee altitude. Not applicable in the re-entry situation. Displayed in nautical miles. XXXX.X

R2-Perigee altitude. Displayed in nautical miles. XXXX.X

R3-TFF- Time of free fall, in this case it will display the maximum value of -59859 as it is not applicable.

As Stafford states, these values apply when the spacecraft is travelling in a vacuum. As the perigee being computed is 22.2 nautical miles [41.1 km), is well within the sensible Earth atmosphere, the deceleration this atmosphere will impose on the spacecraft, will ensure that the spacecraft returns to the Earth's surface.]

190:51:28 Lousma: Roger, 10. And on your EMS, you can go directly to Range Set and it'll work. Over.

190:51:35 Young: Roger. Thank you. I thought it would.

190:51:38 Cernan: And, Houston, we're ready to activate the secondary Evaps.

190:52:09 Lousma: Apollo 10, Houston. Let's hold off until EI minus 50, about 6½ more minutes, for the secondary Evap. Over.

190:52:17 Cernan: OK. We'll hold off.

190:52:29 PAO: This is Apollo Control. Distance is now down to 9,136 nautical miles [16,920 km], velocity building up now at 19,128 feet per second [5,830 m/s].

190:53:08 Lousma: Apollo 10, Houston. We'd like to proceed with the VHF check now, and we're configured at the sites. If you'll transmit, we’ll listen. Over.

190:53:18 Cernan: Roger. We're reading you right now VHF and short count follows: 1, 2, 3, 4, 5, 5, 4, 3, 2, 1.

190:53:27 Lousma: Roger. You came in way down in the mud. You faded out, then came back in.

190:53:33 Cernan: Roger. You're about three by and down in the mud.

190:53:38 Lousma: Roger. And I've got one more number to change on your entry PAD.

190:53:50 Young: It's OK to get on the S-band, huh, Jack?

190:53:53 Lousma: Roger.

Mission audio

190:54:40 Cernan: Hello, Houston. This is 10. How do you read?

190:54:42 Lousma: Read you loud and clear now, 10.

190:54:45 Cernan: OK. You're still down in the mud. Go ahead with that update.

190:54:51 Lousma: OK. The next change is on EMS range to go, should read 12061. Over.

190:55:01 Cernan: Roger. 12061.

[The previously provided EMS Range To Go value has now been amended to 1206.1 nautical miles [2,233.7 km]. This value will be set up on the EMS.]

190:55:05 Lousma: That's affirmative.

190:55:08 Young: OK. It sounds like you're transmitting on VHF and S-band, too, Jack. Could you go back to S-band only? Over.

190:55:14 Lousma: Roger. S-band only.

[Comm break.]

190:59:30 Lousma: Apollo 10, Houston. We have a change to your altimeter. Your Delta-H will be a plus 57. The recovery ship's on station, the aircraft are enroute. Over.

190:59:44 Young: Roger. Plus 57.

191:00:06 Cernan: OK, Houston. I'm going to activate the secondary Evap.

191:00:13 Lousma: Roger, 10. Go ahead.

[Comm break.]

191:03:20 Lousma: Apollo 10, Houston. There's no change in the weather in the landing area; 2,500 [feet, 760 metres], scattered, and 10. Winds are 120 at 10 knots, a 3-foot [0.9 metres] swell, and we're coming up on our 45-minute check momentarily.

191:03:33 Young: Roger.

191:03:48 Lousma: OK, John. Stand by for a 45-minute check; 4, 3, 2, 1.

191:03:55 Lousma: Mark.

191:03:59 Young: OK. Thank you.

191:04:00 Lousma: Roger.

191:04:02 Young: We need a Go for Pyro Arm to check the RCS.

191:04:06 Lousma: OK, John. We're Go for Pyro Arm.

191:04:09 Young: Roger.

191:04:28 Stafford: Stand by to fire the Pyros; 3, 2, 1.

191:04:33 Stafford: Mark.

[As the CM RCS helium pressurization squib valves are detonated, a thud can be heard on the air-to-ground audio.]

191:04:58 Lousma: Apollo 10, Houston. Both rings look good here.

191:05:02 Young: Roger. They look good to us, too.

191:05:52 PAO: This is Apollo Control. Some 43 minutes now from Entry Interface. Present distance 6,916 nautical miles [12,808 km] out. It's reported that Rescue Aircraft Numbers 1, 2, and 3, staging out of Samoa are now on station. Ground Elapsed Time now 191 hours, 6 minutes. Continuing to monitor air-ground as the crew approaches the separation time at the Entry Interface minus 15 minutes. Now 42 minutes from Entry Interface.

[Comm break.]

191:06:54 PAO: This is Apollo Control. Both rings of the Command Module Reaction Control System have been pressurized. Pyrotechnics are armed, both rings are showing normal pressure at this time.

191:07:48 Young: Houston, how'd it look?

191:07:54 Lousma: You’re looking real good there, John.

191:07:59 Young: Boy, it feels real good. It's a real crisp firing.

[The Command Module Reaction Control pressure system is activated, and the pressure can be heard "gurgling" through the lines. An audible noise indicates both rings of the Command Module Reaction Control System were hot fired satisfactorily.]

191:08:23 PAO: This is Apollo Control. The three rescue aircraft are C130 herkybird turboprop aircraft. Rescue 1 aircraft commander is Captain Jerald D. Parker of Barberton, Ohio. He is with the 76th Air Rescue squadron out of Hickam Air Force Base, Hawaii. Rescue 2, Captain John D. Ott, Milwaukee, Wisconsin, 79th Air Rescue squadron, Andersen Air Force Base, Guam. Rescue 3 aircraft commander is Captain Anthony A. Vanagas, of Carnei, New Jersey, 76th Air Rescue squadron, Hickam Air Force Base. 39 minutes to entry. Standing by on air ground live.

[Very long comm break.]

Mission audio

191:19:47 Young: OK, Houston. The bus ties are on the line okay. Tape recorder is going to rewind. And the Sun is setting just like you said.

191:19:57 Stafford: And here comes the Earth.

191:20:00 Lousma: Roger, 10. And the Batts look good.

191:20:03 Stafford: Roger. It's amazing to see an airglow on the horizon again. Over.

191:20:11 Lousma: Yes. You guys are a little out of your environment now aren’t you?

191:20:15 Stafford: Yes. Didn't see that up there around the Moon.

191:20:21 Cernan: It's a good round one; I'll tell you that.

191:20:55 PAO: This is Apollo Control; present altitude, 4,296 nautical miles [7,956 km]; 27 minutes away from Entry Interface. About 12 minutes away from separating the Service Module from the Command Module; this takes place at 15 minutes prior to 400,000 feet (121,920 metres], or what is called Entry Interface. Still live on air-to-ground.

[Comm break.]

191:24:44 Young: OK, Houston. We’re halfway through the Sep checklist, and we’re maneuvering to the separation attitude

191:24:49 Lousma: Roger. We're watching you.

191:25:37 Cernan: Houston, 10. Looks like we might have a primary Evap.

[Cernan is confirming the primary steam evaporator appears to be operating satisfactorily, following drying out during launch.]

191:25:46 Lousma: That's affirmative, 10. Primary Evap is working.

191:27:06 PAO: This is Apollo Control, 21 minutes from Entry Interface...

191:27:08 Young: OK, Houston. We're in Sep attitude now. We've completed the Sep checklist.

191:27:12 Lousma: Roger, 10.

[Comm break.]

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