G Lunar Surface stuff is still incomplete

See list attachedMarch 7, 196969-PA-T-42APA/Chief, Apollo Data Priority CoordinationG Lunar Surface stuff is still incomplete

On February 27 we held a Mission Techniques meeting which I thought was going to simply edit the “final” version of the Lunar Surface Document prior to its release. To my chagrin we discovered that there are at least two areas requiring much more thought and analysis. We will probably meet again to resolve these during the last week of March. The release of the Mission Techniques Document will have to be delayed accordingly.

Before delving into these major items, there are a couple of other things I would like to mention. The first may seem trivial. It deals with terminology – specifically use of the expression “go/no go” regard- ing the decision whether to stay or abort immediately after landing on the lunar surface. Every time we talk about this activity we have to redefine which we mean by “go” and “no go.” That is – confusion inevitably arises since “go” means to “stay” and “no go” means to “abort” or “go.” Accordingly, we are suggesting that the terminology for this particular decision be changed from “go/no go” to “stay/no stay” or something like that. Just call me “Aunt Emma.”

Last summer GAEC honored us with their presence at one of our meetings and to celebrate the occasion we give them an action item. We asked them how to make the tilt-over decision and to establish the attitude and rate limits for aborting. We haven't heard from them since, on that or anything else except RCS plume impingement. Don't worry, we still have four months to figure out how to do it.

I would like to emphasize that we do not want to trim residuals following the CSM/plane change maneuver. It is recognized that they may be rather large since it is the first SPS undocked burn, but we would rather take them into account by adjusting the ascent targeting than by spending CSM RCS propellant.

Another thing we realized about the CSM Was that we had not definitively established the attitude the CSM should maintain during LM ascent nor whether it was necessary for the MCC-H to compute the associated IMU gimbal angles.

Our biggest problem in this mission phase deals with platform alignments. Specifically, we are still not sure what sequence of alignment options should be used, although, I think everyone agrees we should use a gravity alignment for the actual ascent. The basic problem seems to stem from a lack of understanding of just how the LM Lunar Surface Program (P57) actually works and, in each case, what the torquing angles really indicate. Of course, the thing we are primarily interested in accomplishing is to evaluate the performance – that is, the drift of the IMU – in order to decide if it is working, if we should align the AGS to the PGNCS, if we should update the IMU compensation parameters, if we should lift-off on the PGNCS or the AGS, etc. Prior to our meeting at the end of March, TRW will write out in detail how they think the system actually works along with a description of how we should use it. Guidance and Control Division may do the same. Then, we will all get together with MIT to see if we can get this thing straighten out and cleared up.

Finally, our other big problem has to do with how we should handle the LM location on the moon (RLS) and the CSM state vector, particularly during the first two hours on the lunar surface in preparation for the countdown demonstration and, if necessary, ascent at the end of the first CSM revolution. The point is we will have all the data needed to determine the LM's location but we do not want to change it in the various computers (LGC, CMC, RTCC) unless we can maintain a consistant CSM state vector, too. And, it is not at all clear how we can do all that. This subject becomes another major item on the agenda of the “ides of March” meeting.