See listNOV 1 196666-FM1-142FM/Deputy Chief, Mission Planning and Analysis DivisionIn which some items of interest regarding the AS-206 LGC program status are discussed
Quite a number of things have been going on with regard to AS-206 mission plans, spacecraft configuration, and the LGC computer program development. I would like to take a couple of minutes here to let you know about the latest developments in the latter.
Ed Copps indicates that the program development is proceeding on schedule as far as he can tell, and that the next valid schedule check-point will occur in about three weeks. I suppose we will schedule a review about that time. MIT has been studying the effects of the spacecraft equipment deletions on the program and to date has found nothing that is not accept- able. They did point out that it is necessary for the ground to send certain commands which previously were optional. We did not take time to examine this particular subject in detail, but I would suggest that some- one from the Flight Control Division should get in touch with Tom Price of our Flight Software Branch to learn more about this in detail.
One program change requested by ASPO was for the LGC to issue some addi- tional commands in order that redundant relays could be used in two mission critical circuits. MIT indicated that this program change could be imple- mented without schedule impact since we had already indicated to them that it would be okay to delete several processors from the AS-206 program which were no longer required. Specifically, we dropped out the 3rd and 4th APS maneuvers and the RCS cold soak since they are no longer a part of the mission. We also indicated that we could probably omit the DPS cold soak phase from the mission if that provided a significant saving in program effort or, if it permitted, the use of a more desirable platform alignment. Apparently the alignment which has been chosen for the AS-206 has been some- what constrained by this cold soak phase and makes necessary special pre- launch processing of some sort. MIT is to let us know if dropping this mission phase would be beneficial to them.
Currently there are no open items on the AS-206 program, although MIT is concerned about a couple of things. One is they are not happy about our one-second downlink. They feel that this will not provide enough data for post-flight analysis and are concerned that MSC will soon request addi- tional downlink formats. The second item is associated with the LM space- craft separation from the Saturn. Apparently we have requested that a constant attitude rate be maintained as opposed to an inertial attitude hold which would be simpler to provide. I gather they just honestly don't understand why anyone wants this constant rate mode, although they are programming it. Carl Huss was going to look into this a little bit. Apparently he was not even aware that was the way it was to be. Weird.
Two items were closed out as follows:
a) We have instructed MIT to implement 4-jet ullage in the AS-206 program; i.e., the computer program will command all 4 jets on for the duration of time which would be required if only 2 jets were used. This is to insure that the ullage will be sufficient-for the main engine start in spite of jet failures which have been protected against by the jet select logic in the program. Implementing the 4-jet logic means there is no need for the ΔV monitor nor the changes to the spacecraft jet failure systems which had been suggested. The ΔV monitor, you recall, was a proposed pro- gram change [i.e., MDRB #206-19] which was to inhibit the main engine start signal if sufficient ΔV had not been detected by the LGC.
b) MIT was informed to change the DPS engine start sequence to 10% thrust rather than 30% thrust. This change is beneficial to program develop- ment and to the engine people – a rare occurrence.
I might also point out we had a highly successful meeting with Grumman on October 20th where we discussed their requirements for program tapes and data packages for use on their simulation facilities. As I understand it, everyone agreed that we could provide tapes at any time Grumman requested them with the understanding that they would certainly not be flight quali- fied – in fact, their quality will likely be unknown at the time of de- livery. We also indicated that the deficiency reports accompanying these tapes might be rather crude and incomplete. As a possible work around, it was suggested that Grumman could provide a knowledgeable resident at MIT for the last couple of weeks prior to their acquiring a tape. This person should then be aware of the status of the program when they get it. Actually, Grumman has taken steps to do this – two of their guys were up there just last week to get their feet wet.