Lunar Countdown Timeline Test on LTA-8

PA/Chief, Apollo Data Priority CoordinationDecember 29, 1967EG21-M-51-67EG21/Manager, Mission Support OfficeLunar Countdown Timeline Test on LTA-8

The width of the launch window from the lunar surface is decided by:

a. Delta-h limits in concentric orbit, to allow variable catch-up rate.

b. Maximum range during boost, if RR monitoring is needed.

c. Ability of the crew to successfully complete the countdown within the launch window.

If we are certain that the crew can complete the countdown on time, then a narrow window is suggested. If for some reason the countdown was not completed on time, the crew would wait for the next pass when the comple- tion of the countdown would again be virtually assured.

However, if potential problem can arise during this countdown, we may wish to launch even if the countdown is completed late, since the next countdown might not finish on time either. Built-in hold capability would be needed under such circumstances.

We cannot make such a fundamental decision about the width of the launch window without factual data about the countdown. I suggest that a require- ment be placed on LTA-8 for immediate lunar countdown simulations (perhaps five trials with each of ten pilots) in order to evaluate timeline and hardware problems and in order to ascertain the probability of on-time completion of a countdown. Simultaneously, I suggest LMS simulations to determine how built-in holds can be added to the countdown. The touchdown and lift-off tactics depend upon which launch-window strategy we choose to follow.