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.
