Realism Risk and Confidence

Despite the benefits, Apollo management thought the LLTVs might be too risky to continue. Painfully recalling the Apollo 1 fire, the last thing anyone wanted was for a highly qualified astronaut to lose his life in a training device. After Apollo 12, in January 1970, Robert Gilruth brought together a flight-readiness review board that included the two commanders who had landed on the moon, Neil Armstrong and Pete Conrad, and a variety of Apollo engineers and astronauts, including Chris Kraft, Max Faget, and Jim McDivitt. There had been two crashes so far: Armstrong's and another that also ended safely after a nearly fatal close call. What was the value, Gilruth asked, of the LLTV in training for a lunar landing? Should it be shut down?

The conversation not only concerned the trade-offs of risk and training with the LLTV but also provides a rare window into principal Apollo engineers' and managers' thinking about the optimum human role in lunar landing. They did not all agree.

Armstrong and Conrad were unequivocal. ''Were I to go back to the moon again on another flight,'' Conrad asserted, ''I personally would want to fly the LLTV again as close to flight time as practical.'' He felt the computerized lunar mission simulator was not adequate for training for the last 200 feet of the landing, nor was a large gantry-frame device built at Langley. By contrast, the LLTV gave him a good intuition for pitch attitude, which was difficult to perceive on the LM. For his Apollo 12 landing, Conrad had to make some rather radical maneuvers, pitching the LM over nearly forty degrees in a steep descent, but the confidence he developed with the LLTV allowed him to fly with no concerns. ''We are banking our whole program on a fellow not making a mistake on his first landing,'' Conrad emphasized, and the LLTV helped a pilot with a valuable but immeasurable quality: confidence.

Armstrong, as usual, chimed in with fewer words, but supported Conrad's conclusion. He recalled the LLTV's value in helping him perceive subtle variations in lateral velocities, and in imposing the discipline of time pressure. The LLTV helped him learn how to select alternate landing areas. During training, he said, ''You sort of play the game with yourself, as you fly into a touchdown area and you say no, I don't want to land thereā€”I want to land over there.'' That game, related Armstrong, provided ''the confidence in your own knowledge that you can fly the job in.'' A landing accident would be catastrophic to the entire Apollo program, and the LLTV was like an insurance policy, he said, noting, ''my own conclusion is that we still can't afford not to insure against this particular catastrophe.''52

Astronauts always supported the LLTV, and it supported them: showing lunar landing to be a difficult, risky endeavor of machine control that could be mastered by confidence, experience, and skill. Several Apollo commanders actually mentioned the LLTV training on the radio during their lunar landings. Nearly all discussed it in post-

flight briefings as support during the last critical seconds when they took over semiuto-matic control.

In both the LLRV and LLTV vehicles, computers created the conditions that made it possible to fly at all, raising the question: if the task could be automated to that degree, why not automate it all the way? If only human perception could identify and confirm a suitable landing site that the maps could not reveal, why couldn't the humans direct the automatic system to land there? Some pilots, such as Pete Conrad, landed ''blind,'' solely by reference to instruments, so why not entrust control to a computer? Apollo astronauts tended to conflate visual perception and manual control.

For these reasons, Flight Director Chris Kraft recommended installing an automated landing program in the LM. His idea was that once the commander had selected the landing site and flown the vehicle over it, the computer would once again take over, direct the vehicle to hover, and gently set it down on the surface under automatic control. The astronauts disliked the idea, but the LLTV review board recommended that the astronaut office study an automated landing capability.53 After Apollo 12, the IL added the feature to P66, calling it ''velocity-nulling guidance,'' that would automatically place the LM in a hover and descend it under automatic control. It was never used.

For the astronauts, an Apollo launch was a ride atop a fiery automaton, as they watched dials and indicators, poised for an abort while the rocket executed its sequence of staging, steering, and burns. They spent their trip to the moon largely doing systems monitoring, maintenance, and housekeeping, complemented by star sightings to back up navigation from earth. Major rocket burns were calculated in advance by computer and the ground controllers, directed and controlled by servos. Only when approaching the lunar surface would pilots do what they did best: fly and land a delicate, powerful craft. Yet even there, only the last minute or two of the ten-minute descent would be under manual control. Here ''manual'' meant jogging a stick that would provide new setpoints to computer-controlled feedback loops, either for attitude holds or descent rates. Yet this semi-automatic mode proved sufficient for the pilots and NASA to feel comfortable that the landing was made under human control, with human judgment and skill.

None doubted that the human eye could best assess a landing site and determine the most suitable place to put down the LM. Hence the final trajectory centered on a moment of vision, of perception, of revealing, as the LM pitched over and the commander saw his target for the first time. But what was the linkage between visual perception and manual control? Did choosing the landing site necessarily involve hand-flying?

Real landings, with skilled but fallible people flying magnificent but imperfect machines in less than ideal circumstances, would begin to answer these questions.

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