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TO THE MOON AND BACK

Flight Journal, Dec 2004 by Oberg, Jim

Flying the Lunar Module

ASK ANYBODY WHAT the first words spoken on the moon were, and you'll likely get the classic answer: "Houston, Tranquility Base here; the Eagle has landed."

Neil Armstrong did radio that message to earth on July 20, 1969, but they weren't the first words spoken after the landing.

Lunar Module (LM) pilot Buzz Aldrin talked first when he gave this status report: "Contact light! OK; engine stop. Ay-see ay out of detent. Mode control both auto. Descent engine command override off. Engine arm off. Four-thirteen is 'IN'... "

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As Aldrin gave his report, Armstrong reiterated these critical comments: "Shutdown. Out of detent, auto ..." and "Engine arm is off." Those were the real first words from the moon, and it was a radioed pilot report. Landing the spidershaped contraption was a job for pilots, not fancy speechmakers, and the pilots did their jobs, even if their words about that aspect of the flight have largely been forgotten.

The task of flying the LM was "a pilot's dream." To land safely and then take off and return home, it took Neil Armstrong and Buzz Aldrin all the skills and sang-froid that their lives in aviation had brought them. And their flying machine was literally "unearthly"even bizarre. And its weirdness went right to the core of how it had been built and how it was flown.

For instance, there weren't any foot pedals because the two pilots flew standing up, waist-harnessed to the floor and walls. They each had one small triangular window in front of them and a suite of radars that pointed up or down-not forward. Instead of having control surfaces for torquing the vehicle, they had 16 small rocket thrusters pointing in so many different directions that the craft looked like a porcupine. The thrusters and their main rocket engine were controlled by two joysticks-the left one for translational motion and the right one for rotational adjustments.

They didn't have a compass, but they did have a good "eightball" attitude indicator. A tapemeter-two numbered tapes moved up and down behind a needle-showed the altitude and altitude rate calculated using radar. They also had a computer autopilot in a state-of-the-art computer with the same capacity now as today's high-tech wristwatches and cell phones. And there were more than a dozen panels covered with switches, circuit breakers and various indicators.

On a low desk between the two standing crewmen was the computer console, the "diskee." Either man could reach it, but that required care to avoid tripping over each other or entering redundant commands.

For the descent to the moon, the LM crewmen wore their suits, helmets and gloves, but because the cabin had air, their suits weren't pressurized. The gloves were a simpler version of the outside ones that had a pressure bladder but no thick, thermalabrasion-protection layers of the moonwalk gloves.

Both panes of the LM commander's double-pane window had , scribed, graduated vertical and horizontal scales marked in twodegree increments. During landing, these markings gave him a way to locate the point on the moon where the autopilot predicted that the LM would land. Also, while coasting during descent before he fired the braking engine, he used these marks to determine how quickly landmarks on the surface were moving along the scale, and that showed the LM's altitude. Neil Armstrong recalled that this was a pilot suggestion that the spacecraft designers hadn't thought of: "The visual check was something that we devised ourselves-barnyard math. ... We just timed [landmark motion] on a stopwatch and had a little plot to compare it with. As the altitude decreased, we could see it was converging pretty well. It gave us an alternate check of our altitude."

The markings were also used to take hacks on guide stars as they passed to confirm a good flight path. This was also important because they were still too high for their landing radar to lock on to the surface. When the main braking engine was turned on at 50,000 feet (they were still moving almost horizontally), to turn their radar to face the surface, the crew rolled the LM 180 degrees and wound up facing out into space (their feet were actually pointing somewhere above the lunar horizon). Then, as they curved more and more steeply, they gradually pitched the LM over, saw the horizon come into view and then, the landing site.

At this point, the LM pilot could tap his right-side hand controller to move the designated landing point, and the autopilot would steer to the new touchdown location. For early missions, one "click" moved the target half a degree up- or down-range or two degrees left or right (these increments were changed to one degree for the final three missions).

On Apollo 12, which had to land within walking distance of an earlier robot probe, the moment when the computer-predicted landing site turned out to be correct was dramatically described by pilot Pete Conrad: "OK, we're out of 19,000 feet," he radioed. "I've got some kind of a horizon out there; I've got some craters, too, but I don't know where I am, yet." A few moments later, he added, "I'm trying to cheat and look out there. I think I see my crater." Years later, he explained to a space historian that "I looked out, and I didn't know where the hell I was. I looked fat the computer] and got the number. I looked back through the number, and then I knew where I was."

TO THE MOON AND BACK

Flight Journal, Dec 2004 by Oberg, Jim

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