Upthread: D Rendezvous Ground Rules and Working Agreements update (Sep 23, 1968)
Downthread: D Rendezvous Open Items, Action Items or whatever you call them (Oct 17, 1968)
See list attachedOctober 10, 196868-PA-T-218APA/Chief, Apollo Data Priority CoordinationD Rendezvous Mission Techniques
On October 4 we met to review a draft of the D Rendezvous Mission Techniques. Although we spent the entire day we didn't get past page 3 and so it is obvious we are going to have to beef up our effort in order to get all this cleaned up. In fact, I am going to schedule all day meetings every other Monday specifically for this purpose.
I feel we did accomplish some rather important things in this meeting. The most significant was identifying exactly what pieces of equipment must be working in both spacecraft at each of four go/no go points, namely:
b. Separation into mini-football
c. Phasing into football
d. Insertion into CSI/CDH rendezvous
This is the first time we have made a coordinated attack on this subject and I feel we were probably 90% successful or better. I have attached a table summarizing the results which you may find interesting. The decision as to whether each piece of equipment was required or not in order to go on with the mission phase is based on a pretty detailed understanding of how we want to do the rendezvous exercise and how we want to get out of trouble if other pieces of equipment subsequently fail. We adopted, as a general philosophy, that the command module must be prepared to rescue the LM and so we insisted on having redundant CSM capability for all crucial operations. In the LM we were somewhat more liberal assuming that the CMC rescue capability provides an adequate backup for the next LM systems failure for all operations except braking. This philosophy seemed to us to provide the best tradeoff between crew safety and assurance of meeting mission objectives. One item I would particularly like to point out regards the AGS which we feel is not required for anything except Insertion into the CSI/CDH rendezvous. It may seem inconsistent that we are willing to make the phasing burn into the football rendezvous but then not go for the second bigger loop. The reason was that most objectives will have been achieved in the football and the additional experience gained in the CSI/CDH rendezvous does not appear to justify the risk of demanding CSM rescue for subsequent PGNCS failure. Incidentally, the thing we want the AGS for in this case is not rendezvous navigation or maneuver capability but as an attitude reference in the event we lose the PGNCS. This is considered important since without it, it may not be possible to keep the tracking light oriented toward the command module.
Some other items I would like to list briefly are:
a. Whereas previously we had stated the MSFN solution for CSI and CDH would be used to target the AGS, the crew has a strong preference for using the PGNCS solution once it has been tested and found satisfactory. They feel this gives a better burn monitoring. Our main reason for having suggested using the NM solution was to avoid unnecessary activity close to burn time. However, since the PGNCS solution is checked before the AGS targeting is loaded – that concern is not longer valid.
b. We had stated that no radar data would be input into the AGS prior to CSI and CDH. To this we are adding the football prior to TPI₀ unless the PGNCS fails or it is known that TPI₀ will be executed.
c. It has been established that the LGC rendezvous navigation W-matrix will be initially set to 1,000 feet and 1 fps. In addition, it is necessary to set initialization value for the radar angle biases. The value selected for this is .001 radians.
d. We have established a mission rule the flight controllers should utilize in targeting the maneuvers prior to the rendezvous exercise in order to meet satisfactory rendezvous lighting conditions and MSFN coverage. They may permit the Δh for TPI₀ (that is, the football rendezvous) to vary ± 1 nautical mile. The Δh for TPI should be tar- geted to be 10 ± 0 nautical miles. Actually this tolerance variation in the football provides quite a bit of control for the real time mission planner and he should be able to do the CDH targeting to meet the TPI Δh constraint.
An open item still hanging around deals with whether or not an AGS gyro cal- ibration should be performed during the rendezvous exercise. I believe both GAEC and GCD have stated it should not for fear of screwing up the AGS gyro calibration. TRW's AGS people, I believe, would like to have the calibration done since they feel it would greatly improve the accuracy of the system. Of course, everyone agrees with that providing the calibration works. We must vote everyone concerned with this again, I guess; right now the crew has included it in the timeline while docked to the CSM.
LM systems required to continue the exercise assuming that CSM rescue provides an adequate backup for failure (except braking).
SEPARATION INTO PHASING INTO INSERTION, LM SYSTEMS UNDOCKING MINI-FOOTBALL FOOTBALL CSI/CDH
PGNCS LGC R¹ R R R IMU R¹ R R R AGS³ AEA NR NR NR R² ASA NR NR NR R² CES R¹ R R R DPS/DECA NR NR R⁴ NR⁵ RR⁶ NR R⁷ R R Tape Meter⁸ NR NR NR NR Event Timer NR NR NR NR FDAI's⁹ NR R R R AOT or COAS¹⁰ NR NR R R Hand Controllers¹¹ R R R R Cross Pointers NR NR NR NR CSM Tracking Light NR NR NR NR Redundant CSM Systems required to provide LM rescue capability without LM assistance.
GNCS CMC NR NR⁹ R R IMU NR NR⁹ R R Optics SXT NR NR R R SCT NR NR R R COAS NR NR NR NR SCS BMAGS NR NR⁹ R¹² R¹² GDC NR NR NR R FDAI's NR NR⁹ R R SPS NR NR NR R DKSY¹³ NR NR R R Handcontrollers R R R R EMS ΔV Counter NR NR NR R Event Timer NR NR NR NR LM Tracking Light NR NR¹⁴ R R 1. Either PGNCS or CES required since “Direct” is assumed acceptable for docking. 2. Assuming additional experience gained in the CSI/CDH rendezvous does not justify the risk of demanding CSM rescue for subsequent PGNCS failure. 3. Includes DEDA. 4. Alternate mission may be possible. 5. Nominal trajectory possible with APS/RCS. 6. Includes transponder. 7. Separation acceptable if some important test objectives can be accomplished. 8. Assuming RR self-test (V62) provides raw RR readout. 9. One or the other required – not both. 10. Assuming rendezvous navigation studies show uncalibrated COAS IMU alignment is adequate to make flight meaningful. 11. Translation and at least one RHC. 12. One/channel. 13. Crew to verify one CSM DSKY adequate to perform rescue for SPS burns and navigation. 14. Assuming running or cabin lights are visible at 2.5 NM.