This note is in response to your query regarding the “quick return” capability being provided in the lunar module (LM) for aborts during the lunar descent phase. As you recall, I reported deletion of a program in the LM computer for generating coefficients to be used in an abort polynomial to retarget the LM powered…
Category: Lunar descent
There are differences in the descent guidance programs on AS-503 and AS-504
It is currently intended to include some sort of tests of the LM descent propulsion and guidance on the AS-503 mission. However, it is not possible to use the same guidance equations on AS-503 as will be used on the AS-504 lunar descent. This is due to obvious differences of an earth orbital mission compared…
Significant modifications currently planned in the Apollo Spacecraft Computer Programs
Quite a number of decisions have been obtained from the Apollo Program Manager affecting the development of the AS-258 and AS-504 spacecraft computer programs which I am recording here for my own later reference. As usual, I will send it along to you on the chance that you might be interested….
Does the landing radar mess up?
This memorandum is to request that you look further into the business of how the use of landing radar observations in the spacecraft computer during descent influences the onboard determination of the final landing point. Hopefully, the landing point is essentially fixed prior to processing of the landing radar data but that may not be…
Data Priority meetings schedule
In order to get a little bit more orderly in our conduct of the Trajectory Control Data Priority business, it’s evident that we must schedule meetings on a pre-established, periodic basis. Accordingly, the Ascent and Descent meetings will take place on alternate Tuesday afternoons; Rendezvous meetings will be held of Wednesdays, one mission in the…
Descent phase to be added to your Apollo Mission Techniques document
TRW recently completed the attached chapter to be added into the appropriate vacancy in the Apollo Mission Techniques document I sent you recently. As was the case for the other mission phases, this section on Descent was done essentially without participation by other than TRW personnel. Accordingly, I expect it will be modified substantially before…
First meeting of the Descent Phase Mission Techniques Working Group
This memo is to request your participation in the detailed development of the Apollo Mission Techniques for the Descent phase of the lunar landing mission. We are setting up a small working group of the following composition to do this job:…
More about LM radar rendezvous data processing
This note is in answer to some questions you scribbled on the bottom of my LM radar observations memo (67-FM-T-81). You asked if there is any smoothing process on the LM radar data prior to its input to the spacecraft computer. My understanding is that there is not. That is, when the computer wants it,…
Current status on the LM DPS engine gimbal caution light problem
This memorandum is to report the results of a very brief investigation into the adequacy of the LM Descent Propulsion System (DPS) engine gimbal caution light. Briefly, this light comes on if a difference between the gimbal drive signal and the gimbal response signal from the Y or Z axis trim malfunction logic is sensed….
What is the effect of uncertainty in the lunar potential on spacecraft computer program performance
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…