Under paragraph 1, we skip straight from item ‘d’ to item ‘f’. I wonder if this is a subtle Tindall-esque hint that the ‘E’ mission is being considered for deletion?
Upthread: Seventh “D” Mission Rendezvous Mission Techniques meeting (Apr 02, 1968)
Downthread: Rendezvous maneuver targeting for guidance system backup (Apr 23, 1968)
See list belowAPR 16 196868-PA-T-77APA/Chief, Apollo Data Priority CoordinationList of “D/E” Rendezvous open items
1. On April 8, we had our first weekly “D/E” Rendezvous Mission Techniques meeting. We spent the whole time going through the main flow charts. This memorandum is not really minutes of the meeting, but rather a list of questions and action items. We are assuming that both the “D” and “E” missions will utilize the Colossus CSM computer program. If this turns out to be wrong for “D”, we will have to go back and make some modifications on items which we are attempting to flag out now.
a. It is necessary to establish some sort of decision logic based on the trajectory situation and spacecraft systems status for use during the mission to give a go/no go for performing the rendezvous exercise.
b. Flight Dynamics controllers (FCD) are to check into the capability of the RTCC to compute a REFSMAT referenced to the local horizontal at some non-burn time. Previously, we have been told that they could do this, but the people at this meeting were not so sure.
c. I am to recheck and make sure the Sundisk, Luminary, and Colossus all have been modified to permit use of a ground computed REFSMAT. Sun- disk, of course, requires an awkward manual setting of a flag bit.
d. We still have to establish what REFSMAT the CSM should use for the rendezvous exercise.
f. There was a lengthy discussion regarding which spacecraft computer program should be operating during the period from the undocking to the separation maneuver. Basically, it was a question of whether the “average G” program (P-47) should be running. If it were, the crew would utilize the PGNCS to monitor their small separation maneuver. However, there was concern the accelerometer bias could foul up the state vector. We must determine what the degradation would be over this period of time.
g. Trajectory design people were requested to bias the direction of the phasing maneuver in order to insure that a suitable elevation angle for TPI will be achieved in the event an abort in the football phase is necessary.
h. Ed Lineberry's people were also requested to determine the proper elevation angle to be used for TPI in this event. Actually, we must establish the entire technique to be used including such things as whether or not a delay should be planned between the LM and CSM TPI maneuvers.
i. Guidance and Control Division was requested to report on inter- ference to be expected in the docked configuration of the command module in the field of view in the AOT. Docked alignments are planned in these missions and it is necessary to establish which detent position should be used.
j. Another lengthy discussion involved the procedure for separately synchronizing the AGS “clock” to the PGNCS. It is still not clear how this should be done. Al Nathan (GA?C) noted that some work on this had been carried out in their simulator which he will report on next time. Although, it is anticipated that differences in the order of one second are probably acceptable for rendezvous, something much better than this may be necessary on a lunar landing mission for purposes of ascent and descent guidance systems monitoring. Accordingly, it may be desirable to get experience on clock alignments on these development flights compatible with the lunar landing mission.
k. FCSD will report next time on the manner in which the PGNCS and AGS will be used during the phasing burn. Primarily, questions dealt with what sort of attitude the AGS would provide prior to the burn (inertial hold or orbit rate torquing). We are also interested in how the PGNCS, operating in the P-30/P-40 programs can be faked our during the AGS burn so that it will navigate correctly to provide the capability of trimming delta V residuals.
2. The next meeting is scheduled for Monday, April 15. at 9 a.m., Room 384 of Building 4, where we will continue the tedious process of going through the flow charts. We will start where we left off – on page 2.