Goodies affecting the RTCC gleaned from the 504 GSOP meeting

FM5/Technical AssistantAUG 28 196767-FM-T-68FM/Deputy ChiefGoodies affecting the RTCC gleaned from the 504 GSOP meeting

I am writing this memorandum to you in your position as RTCC program coordinator for MPAD. During the lunar landing GSOP review of August 16 and 17, I noted a number of items discussed which had some bearing on the RTCC program. I would sure appre- ciate it if you would look them over and see if the RTCC is able to do the jobs we assumed that it's being set up to do and/or is consistent with the spacecraft computer programs.

1. There in a routine which MIT proposed for the CMC called lunar landmark selection (R-35) which we intend to delete based on the assumption that the ground can perform this function better and easier. What it does is to recommend the best five landmarks stored in the CMC to be used in lunar navigation. They are presented to the crew in order of priority with the landing site as number 1. I assume the RTCC is already prepared to supply this information in the proper format.

2. It was decided that coordinates of earth landmarks used for navigation would be in coordinates of half latitude ( ϕ/2 ) and half longitude ( λ/2 ) in order to obtain the necessary precision. These values are given to three decimal places. If it is intended to supply coordinates of landmarks from the ground, obviously they should be consistent with that unique system.

3. While in lunar orbit all altitude, apogee height, perigee height, etc., DSKY displays will be referenced to a spherical moon with radius equal to the current estimate of the landing site radius. (The only exception to this is the processing of landmarks which are ref- erenced to a pre-established moon model.) The point hero is that if sextant measurements are made onboard the CSM the estimate of the landing site radius will probably change and it will be desirable to make the RTCC consistent.

4. The lunar orbit insertion (LOI) prethrust program, P-32, is another good candidate for deletion. In fact, based on our recent discussions it is probably we may not even want to target for a circular orbit, but rather cut off the engine somewhat early in order to make the powered flight monitoring safer. In any case, if we delete this program it will be necessary that the RTCC targeting be made consistent with the standard Lambert prethrust program, and it may also be desirable to change the RTCC program to target for non- circular orbit.

5. Another deletion candidate is the lunar orbit plane change and circularization prethrust program, P-33. I assume it should be no problem to depend on RTCC targeting for this maneuver, in fact, I think we always assumed the ground was prime.