MSC-07631 18. Command module systems operations

Evans

The first one is subsystem modes. All we did was utilize the nominal modes of the inertial subsystem. We had no problems, with the exception of one. And I think I should let the CDR talk about that one. The ISS worked real fine. The drift on the platform was phenomenally low. Most of the torquing angles were, within a 12-hour period - .0 blank, blank, or something most of the time.

With the LM aboard, I seldom saw any stars through the telescope, so I had to rely on PICAPAR to put a star in the sextant. Once the star was in the sextant, you could assume that it was a correct star because we always had a good platform. If we had needed to do a realignment or a P51, I think the only way we could have done that was to get an initial alignment on a Moon/Earth type of system.

The only degrading factor about the optical subsystem was the focus of the sextant, and you just couldn't quite bring the reticle of the sextant into focus. If you cranked the reticle brightness all the way up, you could see the center of the sextant. However, if you cranked it down a little bit, it was hard to see. And even with full bright, it was a little difficult to see, so you never really had it in focus. If you pointed the sextant close to a bright object , for instance, close to the Moon or close to the Earth or close to the Sun, the reticle brightness would be completely blanked out and you'd end up with a black line and two sets of reticles. One would be a heavy black line, and then there was kind of a ghost reticle behind that which wasn't superimposed on the heavy black reticle. I don't know what that was , so I always used the heavy black reticle.

Schmitt

It's not of major importance, but it's interesting that you were continually saying that it was hard to pick groups of stars and to identify groups of stars in the telescope when you could look out the window, as long as the Sun was on the other side of the spacecraft, and identify constellations with no problem.

Evans

This was particularly true on translunar coast. Even if the Sun was behind you, the reflection off the LM's radar box or RCS quad would interfere with the telescope's field of view. Now on transearth coast, if the optics were looking down-Sun, you could pick up constellations; however not as bright as looking out the window. Around the Moon, even in earthshine, which was very bright, you could pick out constellations. However, they were considerably dimmer than they were in the double umbra on the back side of the Moon. On the back side of the Moon with the double umbra, you could look out and almost see constellations as well as you could by looking out the window, but not quite as well.

Schmitt

I looked once or twice through the optics at the Earth. It appeared to be an excellent Earth-viewing system.

Evans

Yes, it is. A couple of times, I observed the Moon through the sextant. However, the field of view through the sextant was so small that you had to look through the telescope first to see where you were and then look through the sextant because you couldn't recognize the general features at all.

Schmitt

Trim displays and SPS displays - Were they all what you expected?

Evans

Evidently, from where I was sitting in the cockpit, plus 2 and minus 2 on the gimbal drive check always ended up a plus 2.2 and a minus 1.8 from my left seat viewing angle.

The trim values were always just a bit higher than what I thought they should be, which didn't bother me much either. I finally got so I would set the SCS gimbal trim position just a bit higher than what I thought they ought to be.

Schmitt

During those checks, each movement of the gimbal was indicated by an increase of amp loads on the buses.

Evans

The other thing that's more noticeable in the vehicle than in the simulator was the feeling of the dynamic motion every time the gimbals move. You also got an indication on the rate display. If you were in the 51 setting, rate display would go up to maybe a tenth of a degree before it would null itself out again. You could definitely see the spacecraft banging back and forth within the dead band.

The CMC SPS TVC - I think the greatest difference in that field and the simulator was in the roll rates involved in the SPS TVC. In all of the burns, the roll rates were almost always up around 0.4° per second within the dead band. In the simulator, it always stayed on the same side of the dead band. But, in the actual vehicle, it would hit one side of the dead band, bounce back, and go back across again at about 0.4° per second and hit the dead band on the other side and then come back. So it was oscillating back and forth across the dead band, whereas we had the simulator pretty much set on a 0.1° per second. I think it always hits one side of the dead band. The pitch and yaw rates during the TVC/SPS burns seemed to be almost steady, very little change. When you had the yaw change during TEI, it was a nice gradual change. The rates were not noticeable at all; just steady as a rock.

The only part utilized in the SCS system was attitude control during the TVC checks, and I guess the other time was when NOUN 20 got its glitch. We switched to SCS control, which took care of the rates right off the bat, caged the BMAGs, and maintained attitude quite adequately. I guess entry was the only other time I used SCS minimum impulse on the command module only, after command/service module separation. And, in that case, you always had residual rates, which wanted to yaw the vehicle to the left. You had to continually yaw it to the right, and in pitch when I was trying to pitch down, it would continually decrease the pitch-down rate. It was essentially evolving its in body pitch up. But, minimum impulse, control of the command module only, is quite adequate. It's a little bit different than the simulator in that in the simulator, roll control is the one you can't quite get with one minimum impulse blip back into zero roll. In the vehicle's case, it's yaw. You'd either give one blip, and it would go to the other side. You'd give it a blip back the other way, and it'd never end up with a zero rate in the yaw axis. However, I never did try it with the single ring authority. The only maneuvering I did again is the minimum impulse on the command module in SCS.

Thrust vector - We never did any SCS/SPS burns.

Power up/power down. We never did power down. It was powered up all the time. We never did power it down. Attitude hold worked quite well. Whenever you switched to SCS control and you had all 16 auto RCS selects on, then you had a continual bang, bang, bang, back and forth within the roll dead band. If you put limit cycle on, that kind of knocked it down a little bit. But, of course, the best way to control SCS in roll is to use two-quad authority and not four-quad.

The Delta thrust switch - I would always wait until average g on the computer before bringing the Delta-V thrust A switch. All burns were started on Delta thrust A first. Or, if it was a single-bank burn, it was Delta- V thrust A.

The Delta-V remaining counter and rocker - the EMS Delta-V worked real fine. The difference between the actual spacecraft and the CMS is that in the CMS you can see them count up and down, but in the command module when you held the button down to maximum increase or decrease, the last three digits remain solid. It really counts up, so you wouldn't have time between each of the counters to see the numbers change. It stayed on whatever number it was on. Actually, it just sat there as an eight, a constant eight all the time because it was whipping through there so fast. The Delta-V test worked all the time. There was always a minus 22.2 or 22.1 on all of the EMS Delta-V tests except the one prior to entry, which ended up as minus 27 or something. That's when the accelerometer was picking up some extraneous counts and counting a little bit more than it should have.

SPS thrust direct ON switch - I never did use it.

Direct ullage button - I never did push the direct ullage button. I don't even know if it worked.

Thrust ON button - I never did push the thrust ON button, so I don't know if it worked, either.

Engine thrust vector alignment - I don't recall any attitude deviations or maximum rate changes because of thrust vector misalignment at the initiation of any of the burns.

SPS chamber pressure indicator - During the LOI burn, the bank A indicator came up to about 87 percent, which was a little lower than anticipated. I was expecting somewhere around 95 or 97, somewhere in there. That's about 10 percent lower than expected. When I turned on bank B, I got the nominal 5 percent increase, and then throughout the LOI burn, the chamber pressure just gradually increased a little bit and finally got up to about 97 percent at the end of the burn. The other anomaly on the chamber pressure indicator was that after the LOI burn, we noticed that we were down around 5 per cent , and then later on, sometime in lunar orbit, it ended up back at zero again, and I'm not sure when it went back to zero. On all the rest of the SPS burns, the chamber pressure on bank A would always come up to about 86 to 87 percent and then a 5 psi increase when you put on bank Bravo.

Schmitt

PUGS - The PUGS was essentially nominal in general. Apparently, there were some sensors out, so it was erratic in its sensing of the LOI burn. It tended to hang in the decreased area. I went to decrease and left it in decrease for the LOI burn, and it seemed to try to keep going low. After DOI, we didn't see any real change to it. Then I guess it acted pretty much the same for you on circ. When I came back in, it looked like it had decreased more than when I looked at it last.

Evans

Well, on the plane change burn, the ground called up saying to start it in decrease. So I went to decrease, and I think it didn't have time to stabilize at all because we ended up with a gage with data of 400 decrease.

Schmitt

When we picked it up after that for TEI, we started TEI full decrease and left it there. It was, in fact, low and gradually worked itself up until it was almost balanced about 30 low at the end of the burn.

Evans

That's with the switch in full decrease.

Schmitt

And that corresponded with what we read on the gages. So, I guess you'd say it ended up nominal, but it was a little erratic during the burn, and that may have been the result of those sensors.

Evans

I think I'd better back up there a little bit on the chamber pressure indicator. Evidently, the chamber pressure indicator had a bias on it on the low side because we were definitely getting full thrust.

Schmitt

Yes, in checking the V go versus time chart, you were ahead of that on V thrust. You were getting more than the nominal thrust and that corresponded with our cutoff time.

Evans

Service module RCS - We had no anomalies with any of the quads. The audible cues are not like the simulator, but you can hear some back there. You hear something that's more than the clicking of the solenoids on and off. I don't know what it is, but it's more than the solenoids.

Schmitt

As a matter of fact, it was like somebody in another part of an old house turning on a water faucet and when it's turned off, you hear the water pound against the faucet. I think it probably was the plumbing more than the solenoid.

Evans

Whenever you started a maneuver or were in a maneuver, you could always tell because the vehicle would vibrate a little. The vehicle would move around and when it got to its position, it would sit there and shake a little bit, and then when it started moving, it would also shake a little bit, more than I had anticipated that it would do.

The command module/RCS - We had no anomalies there.

Schmitt

I guess I was impressed by both the service module and the command module firings at the amount of unburned fuel and/or oxidizer that was propelled out of it. My impression was that the command module gave more afterburn material than the service module, but that may be because I was closer to the command. module and I watched it. Also, in regard to the service module evasive maneuver after separation, it was very clear what was taking place. You could see those particles streaking out.

Evans

I guess the other thing is, whenever an engine fired at night or on the dark side of the spacecraft, you always got a white flash.

Schmitt

Fuel cells were perfectly nominal as far as I could tell on board, and the ground didn't call anything. The one switching anomaly we had was that, in the process of some activity, one of the fuel cell pumps got turned off, and I don't have any idea how that happened. It obviously happened on my watch, and they caught it within 5 minutes.

Evans

Well, I turned the laser altimeter off one time when trying to maneuver to a position to see out the window. My feet were flailing all over the place, and I kicked them off with my toe. I must have. So, I think that's probably the sane thing that happened with the fuel cell.

Schmitt

In high power loads, we did see some caution warnings on the O2 purges, which I didn't expect to see, but it was just barely triggering the high flow. The ground called saying not to worry about it. The batteries were nominal as near as I could tell. I never did quite figure out whether the ground was concerned about the vent pressure after charging because it hung at 0.6 for a long time and then gradually creeped up. They didn't seem bothered enough about it to discuss it with us, so, I ignored it too. It was always within limits. The only thing that I was a little bit surprised at is that they left the batteries uncharged longer than I had expected. I expected more calls. We never really got our entry batteries charged up until the day before entry. We had time to charge them before then. It seemed to me that after TEI we waited a long time to get the batteries back to charge, but that's a minor point.

We launched with our batteries down more than normal, so that's probably what started us off in a real-time call in the battery charging because we left battery A charging - I think it was A first - for a long time, practically 24 hours, I think. I'd have to go back and look, but it was a long time recharging. And when we put it on, it carried over 2 amps on the battery charger, which is impressive because in the simulator you never see more than 1. The battery charger was, as far as I could tell, perfectly normal.

Caution warning - Very soon after insertion, we got something like 7, if I remember correctly, before we had comm with the ground again, spurious master alarms. It gradually became evident to us that it was associated with switching panel 2 switches. Ron hit it with a helmet once. It was with the neckring, and he got an alarm. During the pressurization for the first LM entry, we got a couple more. I thought it might be associated with a higher pressure cabinet. That's the only other correlation with that anomaly. I guess after that, we never saw it again.

Evans

Well, one thing we want to mention is that we never got a caution warning light.

Schmitt

The gages - There were no anomalies or power levels that I jotted down at various times to keep track of any possible shorts. Things seemed to be perfectly normal, and anytime it jumped up, you'd always be pretty confident that you could look up and see that the O2 meter should have come on. There was one time when I thought I saw a major blink on the lights when we weren't expecting any power surge. The ground couldn't find anything on their records, and I suspect it was my imagination.

AC, nothing - I was surprised as I always am, and I've seen it in the chamber that the AC-1 voltages were as low as they were. They are right down at the lower limits, but they're not below the limits. We've asked that question in chambers, and nobody ever worries about it, so I'm sure that's standard.

AC inverters, perfectly normal - We did run inverter 3 for a while as a heat source when the cabin got cold during some of the weird SIM bay/transearth coast attitudes in conjunction with manual control of the mixing valve.

Main bus tie switches, no problem - One surprising thing was the first time I put them on at launch, during the first try at launch, the fuel cells apparently were performing much higher than I was used to seeing on the GSE in the chamber. Very little current was drawn from the batteries.

My normal mode of monitoring the bus ties to see if they got it or not was to watch the battery amps, and in those particular cases, I got no indication (for a few seconds anyway) of any amps off the battery. Gradually, a little came up and you could see there were 2 or 3 amps. Then when we checked the gimbal motors. (The batteries were not a good place to check the gimbal motors.) I went to fuel cell amps to check gimbal.

Evans

I always used the fuel cell amps or the O2 flow.

Schmitt

On the simulator, I always used the battery flow. That's another thing I might mention is that the H2 and O2 flow in the fuel cells aren't any good for that because they're too sluggish, much slower than the simulator. The simulator reacts instantaneously to changing loads, whereas the real fuel cells are quite sluggish in their reaction. The sensor bus switch, we turned off once for EVA.

The cryogenic system - The ground was playing games with the H2 fan because of a thermistor shift, scale change or something like that. We did a lot of manual switching on their call, but that was no inconvenience whatsoever because they had a sleep configuration that they could go to and it didn't bother us at all. One thing, it seemed that we, at least as far as the tank pressure was concerned, carried our H2, 1 and 2 tanks, with us after the service module jettisoned. I don't know why.

Evans

This is a good point to mention, the surge tank was biased a little bit low, too.

Schmitt

That's right, but we were alerted to that. It performed just as the alert specified.

Cabin lighting controls - One thing we didn't use initially but used later on transearth coast was the fixed position being brighter than the maximum on the restat.

Evans

I used that a couple of times trying to get enough light in there to use a camera.

Schmitt

Split bus operations - They worked fine.

Evans

Oxygen masks - We never took them out of the bag. With the gassy situation in there, I was tempted to, but we never did.

We very seldom, utilized the cold water dispenser.

Cernan

Most of the cold water came out of the gun.

Evans

It was handier; that was the reason. You wanted to keep the hot water hot so you keep it going. The water-gas separator stayed on the hot water tap, and we always ended up with gas bubbles generally of about 1/2 to 3/4 inch in diameter in the hot drink or hot beverage, things like that. In the cold water drink gun, seemed like there were a lot of very small bubbles - just little bitty ones maybe a centimeter in diameter that would end up in the drink gun.

Schmitt

The hot water bubbles were bigger.

Evans

Suit circuit - No problems. We mentioned the difference in the bias on the surge tank already.

Cernan

The waste management system was all right as far as the CSM was concerned. I still think it's a poor system from a standpoint of hygiene in waste management control. I made that statement in different sections and I'll specifically say any time you use a condom-type system you want to make the valve end of the condom of a larger diameter so that whenever you reroll it for the next use, you can reroll to a larger diameter and get your penis as far up in the system or towards the valve that you possibly can. If you don't, you have to stretch and pull the condom and half the time your penis might be part way in and half the time it may be all the way in. Any time it's not all the way in the condom, you can almost invariably end up with urine residual in there that has to be cleaned up in one way or another, in spite of the fact that you tend to push it through the valve like it's recommended. The entire system still needs improvement.

Evans

It still needs improvement and in my case the condom was too small. In other words, I anticipated a shrinkage and the shrinkage did not occur.

Cernan

I did too but I think what I just mentioned would tend to solve that. It's getting it over the head really.

Evans

That's right. That's right. We said everything we want to say about waste management. We stowed everything in the waste stowage compartment except for two feces.

The CO2 absorbers - No problems this time. Nothing sticking.

Cernan

Telecommunications - The whole thing was nominal.

Evans

The high gain worked great. There wasn't any problem with that.

DSE operation - Ground handled most of it and where the ground did not and the CMP was required, we just said configured and we did it that way.

Tunnel and hatch probes - All operations were nominal with the exception of the things that are noted on the air-to-ground tapes about the docking latches.

---

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.