Tindallgrams

On October 5th, we had the second of our weekly all day program development plan meetings at MIT. Most of our attention was given to the open items on the AS-278 program which I will discuss later, but first I would like to pass on some general comments regarding the work at MIT. Based on their intensive planning over the last couple of weeks, it appears that staffing for program formulation (Norm Sears’ area) and for program coding, integration, and check out (Ed Copps’ area) is now adequate. They foresee no problem in the development of the AS-278/503 and AS-504 programs in these areas. In fact, they expect to be in a position to handle follow-on mission programming in a routine fashion. There is a shortage of people in John Dahlen’s area. These are the guys who prepare the detailed program sequencing – Chapter 4 of the Guidance Systems Operations Plans, for those who are familiar with that. They have several more people scheduled to move into this who they consider to be highly qualified and experienced which should help to relieve the situation. However, this relief will only be for programs developed after AS-278 since that GSOP is currently scheduled for release on about October 17th.

The other problem areas, as I have noted before, are the computer facilities used for program development – namely, the 1800’s soon to be augmented with a IBM360/75. How quickly the new IBM computer will be on line continues to be problematical. The pacing item for this is the so-called MAC compiler necessary for running AGC programs on the IBM machine. And the hybrid computer facility is also constraining as noted previously. Phil Felleman has done a considerable amount of excellent work in laying out the projected schedule of its use based both on the current facility and in the augmented facility which I have described previously. It is our intention to continue the development of the justification for augmenting this facility for presentation to our management at MSC, probably around October 22nd. It is Phil Felleman’s estimate that this equipment could be operational by about February 15, provided they get the go-ahead by the first of November.

Following is a list of the open items associated with the AS-278 mission programs:

  1. Manual takeover of the Saturn guidance during boost into orbit. The AS-278 GSOP presently includes this capability; however, it was hastily assembled and a considerable amount of further thought and planning has been carried out at MSC leading to the desire to change that formulation. It is my understanding that Guidance and Control Division has dispatched the additional information MIT needs to develop this spacecraft capability to MSC’s satisfaction. MIT has been directed to prepare an MDRB – our change control document defining the work to be done and the schedule impact if it is to be done.

  2. Trans-lunar injection (TLI). Guidance of the SIVB by the command module computer for a simulation of the TLI maneuver on AS-503 has been proposed. The objective here is to test the interfaces of the spacecraft with the SIVB; it is not considered essential to check out actual TLI guidance equations, although that would be desirable. Since this is the case, it is possible to utilize to a large extent either the external ΔV or Lambert guidance programs already available in the AS-278 program. The question as to which of these was to be used was finally resolved in favor of the Lambert, even though it requires an additional uplink and pre-thrust program. The reason the Lambert was chosen was that it is expected to be very much closer to the TLI final formulation than the external ΔV, and it is not expected that the development of these two extra processors is a particularly large job. MIT was requested to prepare an MDRB for Lambert steering of the SIVB with a request that if they encounter some problem which use of the external ΔV processor would relieve, they would inform us immediately. Incidentally, associated with providing this capability in the AS-278/503 program, we are informed that the all-digital simulation to support testing of the Saturn steering is in pretty good shape as a result of the work they had done previously. They feel they have a good model of the Saturn steering with the IBM guidance equations, gimbal dynamics, etc. This is a rigid body representation including no fuel slosh or bending, of course.

  3. Lunar orbit insertion (LOI). MIT will prepare an MDRB to include the LOI guidance if they desire. We informed them that MSC was not particularly concerned whether this was included or not.

  4. Stable orbit rendezvous. Jerry Bell (RAB) was scheduled to discuss the changes required to the rendezvous guidance with MIT on October 7th. We decided to delay initiation of the MDRB for this until our meeting next week, at which time, hopefully, the definition of this program change will be more definite.

  5. LGC DSKY/eight ball discrepancy. MIT was requested to prepare an MDRB for the addition of the necessary transformations to make the computer and FDAI displays compatible.

  6. APS and DPS minimum impulse. Aaron Cohen accepted the action item of reviewing within MSC the need for providing these capabilities in this program. MIT was told not to prepare MDRB’s yet.

  7. DPS “30 second” maneuver constraint. MSC is also to review the need for eliminating the current constraint on DPS maneuvers within the 26 to 30 second burn range which are not accurately controlled by the AGC due to automatic throttling at that time. MIT was asked to delay preparation of an MDRB until MSC could establish its need.

  8. IMU alignment backup. It has been requested that a capability be provided to align the IMU through use of the rendezvous reticle in the CSM and the LPD reticle in the LM. This capability is most desirable for the lunar mission where loss of the primary alignment systems would be extremely serious. MIT has requested to prepare MDRB’s for both of these.

  9. Reentry landing point targeting. MIT is continuing their investigation as to the earliest time it is possible to load the latitude and longitude of the reentry landing point. It is still hoped that procedures may be available for input and verification of these parameters at an acceptable time in the mission. If this investigation proves negative, MIT will be requested to prepare an MDBR.

  10. Universal update. Action on this item had somehow been overlooked. It has been our intention to have MIT prepare an MDRB on this for some time, but apparently we had failed to request it. Accordingly, we did so.

  11. Earth orbit navigation. Our old friend was discussed as usual. MIT was informed that our direction to delete this capability had been recently forwarded to them. MIT stated that they felt it their responsibility as the G&N contractor to formally bring to our attention their concern that this action is improper. We jointly agreed that their best course of action was to prepare a letter for the ASPO Manager stating their position on this matter. I must say I don’t feel very strongly one way or the other about this, but it certainly is evident that MIT has a unanimous, sincere opinion. So do some MSC people.

I felt this meeting was quite fruitful and the MIT participation was again very cooperative. We have scheduled the next meeting for October 13th, and after that one, I might even start to tell you what the program delivery schedule actually is. How’s that for suspense?

Terms & Abbreviations

278

see AS-207/208

504

see AS-504

APS

Ascent Propulsion System

AS-207/208

AS-207/208 (also known as AS-278) was to have been the first test of the LM in Earth orbit. It was also to have be a dual mission with the command and lunar modules launched on separate Saturn 1Bs. The mission was cancelled after the Apollo 1 fire and the Saturn 1Bs were used to launch Skylab 3 (AS-207) on July 28, 1973 and Skylab 4 (AS-208) on November 16, 1978. The LM was first tested by Apollo 5 in January 1968.

AS-278

see AS-207/208

AS-503

Before the Apollo 1 fire, the mission referred to as AS-503 was originally scheduled for October 1967. AS-503 eventually launched as Apollo 8, December 23 1968.

AS-504

Before the Apollo 1 fire, the mission referred to as AS-504 was originally scheduled for December 1967. AS-504 eventually launched as Apollo 9, March 3 1969.

ASPO

Apollo Spacecraft Program Office.

CSM

Command-Service Module.

Copps, Ed

Member of the MIT Instrumentation Lab

DPS

Descent Propulsion System.

Dahlen, J. M.

Member of the MIT Instrumentation Lab. Director, Systems Engineering Division, Apollo Guidance and Navigation Program.

E. Copps

see Copps, Ed

FDAI

Flight Director Attitude Indicator. An instrument in the CM used to keep track of the orientation of the spacecraft. Commonly referred to as the "8-ball".

GSOP

see Guidance System Operations Plan

Guidance System Operations Plan

The GSOP was essentially the specification for how the guidance computer and its software where required to work for a specific mission. Many of GSOP’s are available online including the GSOP for the cancelled AS-207/208 mission

IMU

Intertial Measurement Unit

John Dahlen

see Dahlen, J. M.

LGC

Lunar Module Guidance Computer.

LM

Lunar Module. Earlier it was known as the Lunar Excursion Module and abbreviated “LEM.” Even after the name change, it continued to be pronounced “lem.”

LPD

Landing Point Designator. A set of marks on the LM window that helped the crew locate the designated landing area.

MIT

Massachussets Institute of Technology. In these memos, MIT is shorthand for the MIT Instrumentation Laboratory, created and led by avionics pioneer Charles Stark Draper. It is now known as the Charles Stark Draper Laboratory and became independent of MIT in 1973.

MSC

Manned Spacecraft Center. Now known as Johnson Space Center.