Astronaut training with respect to the Lunar Roving Vehicle employed some unique simulators. How could astronauts experience the performance characteristics of the Lunar Roving Vehicle operating in zg Earth's gravity? In September 1970, Donald ''Deke'' Slayton, Director of Flight Crew Operations, sent a memo to the Director of the Manned Spacecraft Center in Houston outlining his recommendations for using the centrifuge at the MSC with the 1-G Trainer, with modifications to the centrifuge to suspend the vehicle to simulate Earth's gravity.
''You requested that we evaluate the centrifuge for -G LRV simulation,'' Slayton wrote in the memo. ''A preliminary evaluation indicates that the trainer can be installed on the centrifuge. Inasmuch as all the simulator hardware proposed for
the Building 5 TDS area (except the overhead trolley) would be required for the centrifuge, we would propose going ahead with the Building 5 simulator first, then transferring the simulator to the centrifuge. Why not do it only on the centrifuge? Because it is unrealistic to drive it on the centrifuge except in a constant speed turn. While we feel it is important to test the vehicle during the turns, we feel it is equally or even more important to see if the vehicle can be driven straight or along a slightly sinuous course.''
Suspending the trainer from the centrifuge operating at a given number of revolutions per minute would impose a certain amount of constant centrifugal force, Slayton pointed out to the Director. The centrifuge would have to be beefed up to support the vehicle and two astronauts. ''In summary,'' Slayton concluded, ''we would propose to test the vehicle at /6 -G in Building 5 initially, then move to Building 29 for endurance-type tests dependent upon results from Building 5.''
This was done, and the trainer was eventually installed in the centrifuge for astronaut training. Jim Irwin and Dave Scott were the first two astronauts to use this trainer for their upcoming Apollo 15 mission. Four special cylinders and cables suspended the trainer to give it the characteristics of driving at /6 gravity; it was identified as the Pogo trainer. Irwin recalled this trainer to Eric Jones of the Apollo Lunar Surface Journal.
"You know, we had good one-sixth gravity simulations with that Pogo device in Houston," Irwin told Jones. "In fact, we could even suspend the little car from this device and remove five-sixths of its weight, so it essentially was at /6 -G. And we could drive that 1-G version on a track. In fact, we used the centrifuge on it. The centrifuge was no longer used as a centrifuge, so this thing was suspended from the centrifuge track, and it would remove five-sixths of the weight, so we'd just drive it on a surface and have that similar bouncing sensation as we would on the Moon. So it was good driving simulations, and of course we also used that to practice walking. The Pogo device was like big suspenders attached to the spacesuit and they'd just remove five-sixths of your weight and you'd bounce along under that. And we could either use it underneath the centrifuge arm, which would follow us, or they even had it mounted on the back of a truck so we could go out and walk or run behind a truck to get the feel of operating on the Moon.''
Dave Scott's recollection of this trainer was decidedly different from Irwin's. "As I recall it was not very effective, and I don't recall using it very much,'' Scott stated in
2005. ''It was difficult to remove all of the 1-G effects. The LRV was so simple to drive and so responsive that actually very little training was necessary, especially since the full lunar terrain was not simulated''.
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