MSC-07631 15. Entry

Evans

Prior to midcourse 7, we did a null bias check and also an EMS Delta-V test. The Delta-V test had been going at about minus 22.2 or 22.1 at the end of the 10 seconds. Then prior to midcourse 7, we ended up with a minus 27. We'll have to check the air-to-ground tapes, but it still was within limits. We'll check the air-to-ground on the actual values of this, but it failed the null bias check by a considerable amount. Since it did that, I went through an extra EMS entry check. It passed that EMS entry check. I can't say for sure whether the .05g light was on during test 1 or not. It was on during the second EMS check. As a result of that, it was determined by the ground that the accelerometer in the EMS was probably putting out a couple of extra pulses. It was decided to change the entry checklist so that we would not put the EMS to normal until .05g time. This is what we did. The .05g light came on, and the EMS functioned correctly throughout the entry. Entry parameters are on the air-to-ground tapes and also on the frames.

The RCS sounds were a little bit louder than we'd been practicing with in the simulator, I thought. I've also mentioned the drifting and the cross coupling and minimum-impulse SPS.

Cernan

Is it louder or more of a bang?

Schmitt

It was less than the LM and more than the service module. That's a good way to put it.

Cernan

Banging on a solid can.

Evans

Communications blackout - You'd never know it from inside the spacecraft.

Ionization - Ionization is bright. It was very bright, very bright.

Schmitt

There seemed to be an early glow. Now, whether that was ionization or the initiation of the fireball, I don't know.

Cernan

They're one and the same.

Evans

They're one and the same, I think.

Schmitt

Yes, but with the true fireball, it would seem to me that that would be something that you really couldn't look at. I couldn't look at it; it was too bright. I couldn't stand it.

Evans

You couldn't look out the rendezvous windows at the fireball because it was too bright. I felt like I should have put on my sunglasses in order to be able to see. That intensity only lasted for about 10 seconds, maybe a little longer.

Cernan

It was longer than that.

Evans

It's hard to remember for sure.

Peak-g - The one thing I can recall about peak-g is that I definitely could not see the peak-g value on the EMS because I couldn't see where the pointer was on the EMS. I determined peak-g by looking at the g-meter. I could read the g-meter, and it was something just less than 7. You're pretty well pinned to the back of the seat at peak-g. You definitely have wrist action with no problem, but trying to raise your arm took a lot of effort. I don't think you'd ever get your arm up if you didn't already have it up at 6g.

Guidance Termination - No comment.

Cernan

Let me talk about guidance for a minute. The CMP was in the left seat, monitoring the EMS, g's, and what have you. I was in the center seat, monitoring CMC and passing bank angle information so we could come to a logical conclusion about giving the spacecraft over to the CMC for guidance. I had the impression after peak-g that the two of us were very close to convincing ourselves that the CMC was not going to roll the spacecraft.

Evans

That's right.

Cernan

It seemed like it took a long time for CMC guidance to roll the spacecraft back out of peak-g. I had the impression that you were just waiting for me to say, "Let's take it back," and we would have taken it. It seemed that it was longer than the simulator. It was a long time before the CMC made its first initial roll command, almost too long. In another couple of seconds, I think we might have taken it over.

Evans

We might have taken it over. I think the reason that we felt that way was because most of the runs that we ran in the simulator were nominal runs where you get about 6.1g. If you get 6.1 or 6.2g, you do reverse the bank angle to a one-eighth roll quicker than you do if you have a higher peak-g. We were pretty close to the 7. I don't know if you ever saw 7 on the DSKY or not.

Cernan

No, I never saw 7g, to my knowledge.

Evans

I never did see 7.

Cernan

I saw 6.64 or 6.65, something like that, but that's about as much as I ever saw. It just occurred to us that the CMC was never going to get around to rolling 180°. Once it did roll 180° to the best of my recollection, it never rolled except from left to right. It never rolled across the top again. It went from 90 or 100 one way, and 70, 80, 90, or 100 the other way but never made the complete turn again. It just rolled left and rolled right, rolled left and rolled right.

Evans

Visual sightings and oscillations - The one thing I forgot to look for was that in the simulator from about 90,000 on down to 50,000, it starts pitching. I don't remember if we ever got that pitch rate going or not. I think most of my comments should be on the air-to-ground tapes throughout the entry. Those would be more appropriate than something I might recall at this point in time.

Schmitt

I think we all had about the same impressions. My standard comments for launch and entry are that there are certain periods of time that lasted for several minutes where I don't think you would be too extensively doing malfunction analysis and problem solving, particularly during peak-g. I think you're mainly concentrating on the g-load, and it would be hard to move your arm anyway to take care of any problem with the switches or otherwise. I'm not saying you shouldn't simulate it. You learn a lot of systems and that sort of thing, but I don't think you can anticipate doing work during that period of time.

Cernan

I thought the drogue deployment was violent. I thought the spacecraft oscillations were quite violent. I'm not saying that there was that much difference than I personally witnessed in the past. I just forgot to expect the violence of the oscillations on the drogue.

Schmitt

I was watching the drogues, and they were moving just as hard as the spacecraft. I think that the drogue movement was being transferred to the spacecraft.

Cernan

We had all drogue deploy, all main deploy, and once we had the mains, apparently we had two good parachutes.

Schmitt

I watched the full main deployment, and I could see all three reefed parachutes after deployment. They stayed reefed probably about the amount of time you'd expect them to. Then you could see the reefing lines start to go, and the two parachutes that were on my right filled fairly quickly and seemed to push the left parachute away and out of the main slipstream. It filled much more slowly. It was clear to me, and it should be in the photographs, that the reefing lines were free. The parachute was not filling. Then gradually, it filled completely. I would say it was 15 or 20 seconds before that other parachute filled completely. It was sluggish. It just got pushed out of the way and couldn't get the full flow of the air to fill it.

Cernan

And I think that some of the people on the recovery team said that they saw the two parachutes plus the streamer.

Schmitt

I wouldn't call it a streamer. It was just unreefed. It was just still reefed.

Evans

I'd like to make a comment about the dynamic visual cues of rotation. Throughout the entry, I didn't really feel that I was rolling. I didn't get a feeling of dynamic roll other than the fact that I was watching the needles. There were no centrifugal forces involved in that operation until we were on the main parachutes. When we were on the main parachutes, I felt like I was lying on my back on a revolving table.

Schmitt

I suspect that might be because of the higher g-loads when all these other things were happening. I don't know how much you were looking at the horizon as you rolled, but that's all I had to look at.

Evans

I could see the roll. I had the visual sensations of it, but I didn't have the dynamic feeling of roll until we were on the main parachutes. While we were on the main parachutes, the roll was not continuous in one direction. It was rolling in one direction at 15° to 20° per second, and for some reason, it would reverse and go back the other way. The rolling sensation on the parachutes was kind of a wind and unwind type of a roll.

Schmitt

The DAC operation was normal. took a little bit of extra footage early of the horizon which I hope turns out. I don't understand why you turn the DAC off after you're on the mains. 'There's no reason to. We ended up with some unexposed footage.

Cernan

Oh, you did? I thought you let it run out.

Schmitt

No, the checklist said, "Stop DAC," and I stopped DAC and it was a little while later that I wondered why I stopped the DAC.

Cernan

I'm sorry. I thought you let it run out.

Schmitt

I don't know if we would have gained anything by it except some more pictures, but there was no reason to turn it off.

Evans

Communications - From 90,000 feet until about main parachute deployment, I had a time trying to hear Jack. There was a lot of background noise.

Schmitt

That's right; I remember that.

Evans

It just gets noisy in the spacecraft from about 90,000 feet on down. Once you get the altimeter off the peg, I had a time hearing you call out.

Schmitt

I was shouting, too. I realized you were having trouble hearing. There was noise. It must have been air noise coming through the hull.

Evans

It was something.

Cernan

You were on VOX that whole time. You could have been keying, and that noise could have been coming through your VOX. I'm not sure. That takes care of entry, which was a good one.

Schmitt

Let's mention ECS. I never was uncomfortably warm in the cabin at all, even through hatch opening,

Cernan

We cooled the spacecraft effectively. Just normal powerup of the ECS systems cooled the spacecraft down prior to entry, and it was comfortable. Even after we landed when it normally does warm up because of humidity et cetera, it was still very comfortable. I never thought it got hot or extremely humid throughout the whole recovery operation. The altimeter read about 100 feet when we hit. We'd been warned that we might hit with 17 feet on the altimeter. We made callouts all the way down on crew condition, altitudes, and the DSKY read-out in terms of position. They had a visual on us all the way down. We were right next to the ship, apparently right at the zero aim point.

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Edits and errors by Eric Hartwell are licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 2.5 license. The original NASA material is copyright-free.