“Any time” LM lift off is an unnecessary constraint

FA/C. C. Kraft, Jr.APR 10 196868-PA-T-75APA/H. W. Tindall, Jr.“Any time” LM lift off is an unnecessary constraint

No big deal, but I'd just like to point out that I don't agree with something in the memorandum to TA/Director of Science and Applications, dated March 19, 1968, subject: Operational constraints for the fourth lunar landing mission, which you signed. It stated in part, “It is the opinion of the Flight Operations Directorate that the requirement to be able to rescue the LM from an “any time” launch phasing situation cannot be eliminated. However, the “any time” launch rescue capability must be available only for the first CSM orbit after LM landing. For all subse- quent CSM orbits, only an “on time” launch LM rescue capability is required.”

As laid out in the attached memorandum, I think we have established a good go/no go for lunar stay technique and I don't see why there should be a requirement for “any time” lift off after the LM has been on the lunar surface for about 12 to 14 minutes. After that, we should always constrain the launch to be on time – to coincide with the discrete time about once every two hours when the command module passes overhead. Of course, RTCC and onboard programs are available to permit launching quickly at other times and for determining the proper rendezvous maneuvers to be made. But the point is, I see no reason to provide allowance in the propellant budgets for the large maneuvers that would be necessary to handle the worst phasing case, nor is it necessary to keep the guidance system in the command module or the LM powered up to support “any time” launch. Also, I think very little emphasis should be given to planning or simulating launches at times other than those specified above, etc..

I would like to see the Apollo work proceed as we have laid out, until someone shows us what is wrong with it and would appreciate you letting me know if you don't think this is a reasonable way to go. Let's simplify the mission and put the burden on the “any time” lift off people, whoever they are, to explain why we need it.