See listJAN 10 196767-FM1-5FM/Deputy Chief, Mission Planning and Analysis DivisionSignificant modifications currently planned in the Apollo Spacecraft Computer Programs
Quite a number of decisions have been obtained from the Apollo Program Manager affecting the development of the AS-258 and AS-504 spacecraft computer programs which I am recording here for my own later reference. As usual, I will send it along to you on the chance that you might be interested.
RCS translation maneuvers:
Although provision was being made in the AS-258 and AS-504 computer pro- grams for G&N controlled RCS translation maneuvers, this capability is being deleted. As I understand it, the flight crew supported this deci- sion which implies that all RCS translation maneuvers in both the command module and LM must be performed manually.
Auto proceed is the misleading term which has gained popular usage to define a capability requested by the crew for simplifying the procedure whereby the computer is commanded to progress on to it's next function with minimum input from the crew. At one time it was proposed that there be no input at all from the crew under certain circumstances. However, at this time the goal apparently is to provide the crew with the capabil- ity of making a “Proceed” command to the computer by a keyboard button assigned exclusively for that function in place of “Verb 33 Enter” – a 4-punch operation. No modification is currently planned associated with this in the AS-258 programs. However, Dr. Duncan has stated that it is his intention to provide this capability on the AS-504 and subsequent spacecraft through the redesignation of the “standby” button.
This program, which provides the capability for the crew to target a mini- mum ΔV, 2-impulse rendezvous sequence of maneuvers, was originally included to provide a flexibility it was felt might be required. Rendezvous mission planning, including aborts at the moon, has now progressed to the point where there is no recognized need for this processor, and as a result it is to be deleted from all Apollo spacecraft computer programs.
LM S-band antenna steering:
Although it had been tentatively decided to drop this capability, more definitive mission planning has revealed that there are critical periods in the mission, particularly during descent, wherein crew activity demands computer assistance in steering the LM S-band antenna to acqui- sition with the ground. Accordingly this capability is to be provided in the AS-504 LM program.
LM platform alignment while docked:
The Program Manager feels some provision should be made for alignment of the LM platform while docked without attitude maneuvering of the craft. The procedure he proposes is for all necessary computations unique to this process to be carried out in the LGC utilizing data already avail- able from the CMC programs. It is probably too late to provide this capability in the AS-208 program, but it should be available for AS-504.
DPS backup of SPS:
At one time there was some consideration given to deleting the DPS backup of the SPS. Since procedures must be developed making large DPS maneuvers docked on the development flights, this proposal has been dropped.
Another major program change which has been under consideration is to substitute for the current landing site targeting a fuel saving approach referred to as “range free”. In view of recent developments associated with the LM spacecraft hardware, this proposal is not considered a require- ment at this time, and so the descent guidance will proceed as it has with- out change. However, analysis will be carried out on the G&C proposed modification to the descent program which would permit a range free option if that should become necessary at some future time. This option will not be included in the AS-504 LM program unless time and storage permit. A decision on this matter probably need not be made for another four or five months.
Our long awaited “Black Friday” review at MIT is now scheduled for Thurs- day, January 12, 1967. At that time other modifications will probably be made for storage reasons based on priority and size of the various proc- essors and their options. It should be lots of fun. I'll let you know if anything interesting happens.