FM13/Chief, Apollo Trajectory Support OfficeNOV 08 196767-FM-T-101FM/Deputy ChiefWhat is the effect of uncertainty in the lunar potential on spacecraft computer program performance
1. Sig Sjoberg called after reading my memo (67-FM-T-98) regarding the impact of current MSFN performance on lunar operations. He wondered why I had not included in my list of studies the effect of lunar potential uncertainty on the spacecraft computer programs. I guess the reason I left it out was that it was somewhat different than those. Specifically, I suggested that we do the analyses listed utilizing current MSFN per- formance regardless of its cause. However, it would probably be useful to make some estimate of the uncertainty in the lunar potential based on out MSFN experience and use that in some additional studies.
2. Two studies that I can think of specifically are (a) the determination of the effect of uncertainty in lunar potential on the onboard computation of the landing site position, particularly its distance from the center of the moon, and (b) determination of the effect of uncertainty in lunar potential on the capability of the LGC to integrate the equations of motion from the time it is initialized prior to DOI until landing—with and with- out landing radar update. I assume both of these tasks should be assigned to the Math Physics Branch. Perhaps you could request them to expand on them and add others that haven't occurred to me.