MSC-07631 20. LRV operations

Schmitt

LRV deployment was nominal. Didn't we almost slip out of the hinge pins there once?

Cernan

I think they dropped into them. The walking hinges did not drop. They were locked in, as we reported. It seemed to have fallen into the hinges. That was the only time when there was a slight jolt. Throughout the mechanical deployment, which followed the procedures as written, she came down just as advertised and broke loose from the saddle just as advertised. The setup was nominal.

Schmitt

We did have to push the hinge pin in.

Cernan

I went back and reset a forward hinge pin. One out of the four hinge pins was not locked in; the yellow was not flush. Mounting and dismounting was simply a case of getting acclimated as to know how to mount and how to dismount. The biggest problem with mounting and dismounting was to be able to mount without kicking dust all over the LCRU.

Schmitt

In my case, the problem was keeping a twist out of the lap belt, which made it difficult to unbelt.

Cernan

Mounting on a slide slope aided dismounting.

Schmitt

Almost all in one motion.

Cernan

Vehicle Characteristics - Power-up - when I pushed in the Bravo and Delta circuit breakers, the gages came up just. as advertised. Occasionally, I could feel a little wheel slippage. To the best of my knowledge, I had four-wheel drive and fore and aft steering the entire time, nominal.

The braking action was good.

As a matter of fact, on some of the extreme downslopes we were on, I had to brake continuously and stay below 18 kilometers. We barely hit 18. I had in mind the fact that the brakes could fade on you. We came down some pretty steep slopes at some reasonable speeds, and I had to brake the entire time. I worked the brakes on and off. I had no indication of brake fading at all. I never felt that I was going to lose control because of lack of braking.

Acceleration - Although we could never really go in a straight line very long with the Rover because of boulders, craters, or general terrain features, I drove the Rover full out a majority of the time. Apparently, we were going upslope, especially out to station 2. I was between 10 and 12 kilometers most of the time, and that was at full throttle. I was a little bit surprised that full throttle did not give me a little bit better acceleration and a little bit better top speed.

Schmitt

I think that 1° upslope was probably there.

Cernan

However, the acceleration when you hit a definite grade or change in grade, you could feel that the capability to climb that grade was always there. In spite of the fact that maybe you slipped down to about 8 or 10 km/hr, you always felt that you had the torque and the power required to make that grade. I never felt that there was a grade that we tried to negotiate that I didn't have the capability to getting over with the Rover. Never.

Steering and Slide Slippage - In 1/6 g with fore and aft steering and four-wheel steering for you, you've got a vehicle that is ready to react the minute you think about putting the command in. Much of the time at the speeds we were driving, as soon as that steering and side slip and sharp turn command went in, you were on three wheels. The reaction was that that you did get side slip. I did feel that the majority of my more rapid or sharp turns, I'd say 50 percent of my driving, resulted in losing the back end on some of my turns. I don't know whether you felt that on the right side, Jack.

Schmitt

Yes.

Cernan

I was comfortable in doing it because I expected it. I felt that in keeping a reasonable speed, the rear end broke loose from me on 50 percent of the turns during my entire driving on three EVAs. It's a vehicle that you have to drive to get accustomed to. It's one you approach slowly, and then you begin to peak out and you begin to live up to its maximum performance capabilities.

You can avoid obstacles very easily. The only hesitancy in doing so is that it requires the same sharp turn and generally your rear end will break out. The turning response is phenomenal.

I was a little disappointed or surprised at maximum speed on what looked like a relatively level surface, which may have been a 1° or so upslope. It was not quite as fast as I thought it might be. Coming down that slope, we did a lot of zigzagging going to different stations. So I didn't get the full brunt of coming back down the same slope. Basically, I felt I could get more top speed out of the vehicle, not that I needed it, but there were times I could have used it in negotiating the surface.

Torque - I don't really think I required more torque. I never lost the wheels going upslope, although I did feel the vehicle working, and you could see it in the amps that you were drawing going up some of those slopes. You could also feel it in the top speed. Again, there was ample torque to negotiate the slopes that we had confronting us. Some of those slopes, subjectively, were quite steep.

Controllability - You had to learn - just like you have to learn on most other vehicles that are essentially like that - to be gentle and smooth during the control. Sharp commands would tend to leave you without the rear end on the ground or leave you with the rear end not exactly where you wanted it. So controllability was excellent, but I felt it was very sensitive.

Crew Restrictions, Limitations, and Capabilities - Displays - I could see and read all displays all the time except when we got dust on the checklist down in front of the hand controller. Then that display became effectively unreadable until I could get off the Rover at the next stop and dust it.

Hand controller operations were as advertised, very similar to the trainer. I used reverse twice, and it worked. I don't recommend it as a standard mode of operation. It's much better to have the vehicle set up for forward only control capability.

Cernan

My seat and foot rest were, as far as I'm concerned, perfectly adjusted and comfortable as far as position. How about yours?

Schmitt: Fine.

Cernan

Crew Movement Within the Suits - As far as driving the Rover was concerned, I had the same right arm restriction as far as getting my arm back and driving the Rover. But I had no wrist problems as on some of the previous flights. I wore no wristlets. I did not rub my wrist raw. I had all the wrist commands. I think that's just a function of where your arms fit in the suit. I had absolutely no wrist movement problems at all. I sat in the suit high enough to be able to see down at the displays and out in front of me. The only restriction I ever had in driving the Rover, out in front, is where coincidentally the last parking angle left the high gain antenna at a planned view. Then I had to look through the high gain antenna. Then the tendency to lose the view beyond was a little bit greater.

Seat Belt Operations - On the left side, I could not have tolerated my seat belt any smaller. It kept me in tight. I felt that I would never lose the Rover. I felt that I'd stay with the Rover even if we did a 180° roll. Yet it was loose enough to get in and out of. It might be because of just generally getting a little bit more tired, but certainly during the third EVA, I found it occasionally was a little harder to release. How about your side?

Schmitt

Much the same. I mentioned that the seat belt got twisted occasionally. I suspect that made it harder to get out. Being tired, I'm sure, had something to do with that.

Let me skip back up to crew movement within the suit. The only time there was any significant movement was when we were on side hills and moving around all the contours. I noticed I was leaning against the side of the suit, which increased the impression of being on a steep slope.

Cernan

During the lunar Rover samples, the commander was able to take the sample from the LMP and was able to reach over and drop the sample in the LMPs sample bag without any difficulty at all. This was repeatable, based upon ground training. Exactly the same.

Schmitt

The Rover sample worked exactly as we had planned. No changes at all.

Cernan

The vehicle suspension characteristics were outstanding. I negotiated some intentionally, some unintentionally. I negotiated some relatively good-sized rocks, 10 to 12 inches or so, head on with the suspension system and the vehicle just walked right over these rocks without any difficulty at all. I tried to straddle the smaller craters so that we wouldn't get any side slope. In driving the vehicle, the major effort is to deter yourself from side slope activities, whether they're little craters or large craters. So you try and go down through the center of the craters if they're not too deep. If they're small craters, you try to straddle them. We went through some relatively major boulder fields, and the vehicle suspension just accepted it without any difficulty at all. I never felt that we bottomed out. We never bottomed out in terms of the wheels taking a boulder. However, we did scrape bottom once or twice in going over some boulders, centering some boulders.

Schmitt

I never went back to look, but you mentioned you looked like you'd bent a wheel. Is that right?

Cernan

I mentioned something about a golf-ball-size dent in the left front wheel. I inspected all the wheels after that. The left front inboard wheel was bigger than a golf ball. If you took a fist and just crunched the inner side wall, just punched it and you left an impression of your fist in it, that's about what I saw in that left front wheel. The impression was probably no more than a half an inch to three-quarters of an inch deep and a radius about the size of your fist. None of the other wheels had it because I inspected them after I saw this one. As far as driving characteristics are concerned, you wouldn't know it was there.

Hand Holds on the Vehicle - The hand hold I used most to get in was the low gain antenna on the commander's side to help me to get in a proper position for strap in. Any other hand holds on the vehicle were really relatively useless, particularly in adjusting the high gain and what have you, because the vehicle when it sets by itself was a very unstable vehicle. The tendency to move or shove or lean the vehicle one way or another was very great.

Schmitt

I used the accessory stands as my hand hold for mounting and dismounting.

Cernan

LRV Systems Operations - The nail system was excellent. I saw the same characteristic digital movement of the gyro that we saw in LRV sim. But it certainly didn't hamper the operation of the nav system.

Power Batteries - The temperature on the right number 2 battery was higher at initial powerup. We started powering up at 120° , which I think surprised everybody, including me. It stayed hot, although they both cooled down relatively. It stayed hot throughout the mission. At the end of the third EVA, it was above 138° or 140° and gave us a flag.

Steering and Traction Drive - I wiped out the hand controller as we had planned to prior to the flight about 6 or 8 times before powerup to remove any lubrication problems due to thermal characteristics. The minute I powered up (and you saw it), to the best of my knowledge, I had both front and reverse steering.

Voice Communications and Antenna Management - Antenna management, because of the extensive preflight planning, was excellent. I had no trouble in handling the high gain. I could pick up the Earth and center it. It was there. I just sighted it and looked through, and it was there. I tweaked it up, and there was no problem at all. The low gain antenna, except when we did 360° pans, which I did not bother to adjust at low gain antenna following on the part of the commander to keep us within plus or minus 10° to 20°, was a simple task. It did not require any undue attention. TV/TCU until the time it failed after lift-off, the TV/TCU worked very well.

Electrical and Mechanical Connections - The only connection I really had trouble with, electrical/mechanical connection, was the SEP connection to the LRV. I had to support the connector bracket with my left hand in order to get enough force on the SEP connector to mate it and lock it to the LRV.

Schmitt

That's the standard EMU connection.

Cernan

That's the standard EMU connection. The only other thing I'd like to mention about the LRV is it's about 99-percent required effort. Even to take a drink of water from the suit drinking bag during LRV driving could put you in some very embarrassing situations as far as following your terrain, craters, and what have you. It was almost 100-percent requirement.

Schmitt

Geology Science Site Response - You've covered pretty well how the Rover performed on various kinds of terrain. Gene, why don't you describe the fender? That was the major dust problem.

Cernan

With the loss of one of the fender extensions, any one of them, the dust generated by the wheels without fenders or without fenders extensions is intolerable. Not just the crew gets dusty, but everything mechanical on the Rover is subject to dust. Close to the end of the third EVA, all the mechanical devices on the gate and on the pallet in terms of bag holders and pallet locks and what have you were to the point that they would refuse to function mechanically even though the tolerances on these particular locks were very gross. They didn't work because they were inhabited and infiltrated with this dust. Some could be forced over center. Others just refused to operate even after dusting, cleaning, and a slight amount of pounding trying to break the dust loose. I think dust is probably one of our greatest inhibitors to a nominal operation on the Moon I think we can overcome other physiological or physical or mechanical problems except dust.

Schmitt

What we're really saying is that in any future operation, mechanical joints or levers and this sort of thing are going to have to be protected.

Cernan

They should be sealed or protected. We had absolutely no dust problem with the wheels, and those are sealed units. Dust accumulated on the radiator.

Schmitt

That goes for tools too. The only tools we had locks on were the scoop and the rake, and those were getting stiff and wouldn't lock. They wouldn't relock once you adjusted them.

Cernan

The period of time when we had lost the rear fender just put a solid coat of gray dust over everything. Once we got the fender repaired, the dust problem was at a minimum. After the long traverse rides, the radiators all required a good amount of dusting. That required X amount of time. That's going to be required again any time we have a lunar surface operation.

Payload Stowage - Jack, do you have anything? Initially, during EVA-1 prep, I think everything fit under the seats or on the pallet. The pallet fit on the Rover exactly as advertised. The SEP, the deployment of the SEP, the setup of the charges, and the charges on the pallet all fit.

Schmitt

I'm sure we'll get into this in the system experiments, but as a general comment for any radiator surfaces that need to be protected, you need to have more than just a cursory design on the protection of those radiators. The SEP is the case in point, and that was a completely inadequate design to protect those radiators. If we ever do it again in a dust environment, you must have clear and very tight protection of your mirrors and radiators for driving.

Cernan

Something else that dust penetrates that I don't think has been mentioned before is that it penetrates and deteriorates the capability of Velcro. I could see it on the LCRU covers and the SEP covers. The Velcro pulled off to keep the SEP covers closed, but the Velcro that kept them open didn't pull off but it was deteriorating. If you want to use tape on the lunar surface after what you're taping has been exposed to the dust, you first have to clean that surface off with a piece of tape or something and get the mirror dust off before the tape will even begin to adhere to the surface you're trying to apply it to.

Schmitt

We ought to mention here that the gray tape in general is not very good. It will stick to itself, both inside and outside the spacecraft.

Cernan

I had the impression that the gray tape has been sitting around for 10 years. That's the kind of adherence you had.

Schmitt

The tape on the food bags is what we finally used whenever we needed to really tape something. It is much better tape.

Cernan

The gray tape is very poor tape. We covered the stowage, which went exactly as planned. We had no fit problems with stowage or anything on the Rover.

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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.