TO THE MOON AND BACK

Flight Journal, Dec 2004 by Oberg, Jim

All the crews agreed that the rocket ascent was very smooth. Aldrin reported it was "... just a little bit of slow wallowing back and forth-not very much thruster activity." A minute into the liftoff of Apollo 12's LM, Alan Bean reported, "Kind of wobbles around up here-sure jumps every time those thrusters fire."

It was also, in Aldrin's words "... a very quiet ride." When asked about cabin noise, Apollo 14 LM pilot Ed Mitchell replied, "No; the helmet blocks it out; we weren't paying that much attention to the noise in there." Asked if the ascent was noisy, Apollo 15's Dave Scott replied: "Nope. Hardly heard a thing ... earth launch was noisy. This was very quiet-very quiet! You heard a swishing sound. Shhhhhhhhh." In the air-to-ground tapes, that's exactly what Scott reported in real time: "It almost sounds like the wind whistling, doesn't it?" Many years later, when recalling the sound, he described it as "... the wind was blowing through a window." This was a real surprise: "I don't know what we expected, but nobody had ever mentioned that to us."

As the LM pitched over to the horizontal, the front windows faced the ground and the men were looking straight down. Apollo 12's Pete Conrad reported at two minutes: "What a neat-o ride. This thing is pitching over. It's right on the pitch profile; this is a hot machine."

As the autopilot turned the LM ascent engine off for the last time, every crew reported the same event: "Shutdown." They checked the guidance display to see which velocity errors ("residuals") they had, and if the errors were too high, they trimmed them with the thrusters. Then they had time to editorialize: "Well, that was a pretty exciting few moments there," Apollo 14's Ed Mitchell commented.

Its fuel exhausted, the small ascent stage weighed less than a tenth as much as the fully fueled two-stage vehicle that had headed down to the moon a few days earlier. But the control thrusters were the same size, so they were much more effective in turning the spacecraft. The LM, wrote NASA's official history, "... was a sporty machine once it was rid of its descent stage and much of its ascent engine fuel, and it took skill to keep the skittish bird from dancing about." But skill-natural talent honed by extensive training-is what the pilots brought to the task.

After several hours of maneuvering, the LM approached the waiting Command Module, which had the lifesaving tickets home. After the docking and transferring of the astronauts, film and rocks, the LM was sealed up and sent on its way. It was to carry out one final task-more fitting to autopilot control than its spectacular manned flight: crash onto the moon. This was done both to clear the lunar orbit of derelicts that might interfere with subsequent missions and to generate an artificial "moonquake" for the surface seismometers to analyze. And the autopilot followed orders on the last suicidal dive-yet another difference between computer intelligence and human intelligence!