Upthread: Small program change needed in the AS-501/502 AGC program (Nov 25, 1966)
Downthread: More interesting things about our work with MIT (Nov 28, 1966)
See listNOV 28 196666-FM1-169FM/Deputy Chief, Mission Planning and Analysis DivisionLGC program status for AS-206
We spent a lot of time at MIT last week wrestling with the AS-206 prob- lem. Although in a previous note I expressed some optimism regarding possibility of recovering some of the one month slip MIT draped on us, they have convinced me now that there is really not much chance. As a result we pretty well convinced ourselves that it will be necessary to release a tape on December 27th, our old flight program release date, for manufacturing ropes to be used for spacecraft systems tests at the Cape. At least this “B-release” will be needed unless the Aurora 88 programs can satisfy that requirement. MIT points out that if it is necessary for them to test the B-release assembly and determine it's deficiencies, that effort will result in a further delay in release of the flight program. We are looking into the possibility of doing that sort of program checkout on the Bit-by-Bit simulator here at MSC if it can be made ready in time. It appears to me we can't do much more to improve the situation.
MIT has brought in superstars Alex Kosmala and George Cherry on a part- time basis even at the detriment of program development for the AS-278 mission; we have reduced the program requirements to the limit even to the extent of deleting thorough restart protection – a subject which I shall discuss in a little more depth later. We are retracing the AS-204 footsteps almost exactly and as we did that time will attempt to derive maximum benefit from whatever flight schedule slips are experienced, although right now we certainly can't count on anything like that.
Regarding the elimination of restart protection, I would like to point out that this isn't a closed issue since G&C have expressed much concern over this. Apparently in the design of the Block II computer, decisions were made based on the assumption that restart protection would be pro- vided in the software. They feel the probability of encountering restart situations on Block II flights is relatively high and could result in disaster if not handled properly. Ed Copps made a guess that to provide complete restart protection would cost another couple of weeks for pro- gram delivery, but it must be emphasized that that is just a guess. I gather that it really is a rather complex process to go through the pro- gram and make it completely insensitive to interruptions which can occur at any time. Our current direction to MIT is to provide restart protec- tion for those periods during which the probability of occurence is very high, such as staging from the descent to ascent power. At other times, in the event of an interruption, the computer will send the engine-off signal and will release the digital auto pilot. Protection of the state vector and current time is also provided and mission phase registers are cleared such that no further activity will be called for by the computer. What this amounts to is that things are put into a more or less dormant state which will be known to the ground pre-mission such that it should be possible to issue new commands in an intelligent manner to get things going again. It probably will be a major undertaking in the MCC and may have implications on the RTCC program. Obviously it's not a good substi- tute for restart protection. Therefore, we have requested MIT to examine this subject in more depth, first of all identifying to us procedures to be carried out if we stick with the program as described above, and second to let us know with somewhat more precision the schedule impact associated with more complete restart protection.
Part of our meeting at MIT included participation by Grumman, which resulted in a couple of things. First of all, in response to our strong recommendation, they have finally agreed to send one of their men to MIT on an almost full time basis for the next month or so in order to provide themselves with a first-hand knowledge of the program status as it devel- ops. MIT is completely in accord with this. Another matter discussed concerned Grumman's recommendation that a third APS maneuver be carried out. An on-the-spot assessment of this indicated that it should be possible to initiate such a maneuver from the ground using the APS-2 mission phase processors and that no program additions would be required if Grumman were successful in talking the ASPO office into doing it.
And that's about it –