Apollo Expeditions to the Moon: Chapter 10

Apollo Expeditions to the Moon

CHAPTER 10.2

THOSE COMPUTER ALARMS

Fortunately, in our software review we had insisted on one point: We had to have at least a 10-percent spare capacity in the memory of the onboard computer. We did that to provide for unforeseen contingencies, and that contingency occurred on the Apollo 11 lunar landing. On that mission we used up the 10 percent with those extraneous messages from the high-altitude radar, and in spite of the spare capacity, we nearly overloaded the landing computer. It set off alarms that caused a few seconds of fast thinking, but it was quickly put right and the landing went on to a safe touchdown.

All this critical design review was then followed by a review of all the things that happened during the dry runs before the final countdown, checking to make sure that there were no anomalies that hadn't been identified and traced back to their origins. That was done in the last couple of days before the flight. What we were basically doing was making sure that everybody had done everything that could be done to assure the safety of the mission.

But you can only do so much in ground simulation and analysis, and then you've got to test the articles in actual flight. One example of this was with the docking mechanism, which presented no particular problems in ground tests and in simulation. But the first time it was tried in space, they had considerable difficulty getting the mechanism into place. That led to a very rapid redesign of the mechanism between flights, which was just one of the things accomplished in the very short time between flights. Looking back on it, it seems amazing that we were able to do a number of things on those two-month centers that would have been considered flatly impossible only a few months earlier. The key to that ability, though, was getting ourselves organized and then finding the will to do things. That made all the difference in the world on the Apollo program; there was the highest motivation, and it produced results, time and time again.

Of course, after the flights we had a thorough debriefing and evaluation of the mission, and of the behavior of the spacecraft and other systems, checking the actual results against our predicted performance, analyzing actual anomalies against ones that we had expected and planned for. The rigid discipline of postflight analysis and the preflight reviews were among the most important inputs of Apollo management to the success of the program.