See list belowOCT 18 196767-FM-T-84FM/Deputy ChiefThere will be no manual input of range data capability in spacecraft rendezvous navigation
1. During the week of October 2 A group of MCC and MIT people com- pletely defined the lunar landing command module and LM programs in “GSOP Chapter 4″ format including all the crew required rendezvous program modifications and GSOP review open items. This note is to inform you of one of the basic decisions reached during that effort, namely that the capability of manual input of range and/or range rate information will not be provided in either the command module or LM computer programs. Of course, LM radar data is automatically collected and processed in the LGC and data from the new VHF ranging decide being added in the CSM will be automatically obtained and processed by the CMC. This decision certainly seemed logical to me based on the following rationale.
2. The command module only computes rendezvous maneuvers starting with TPI and has both a sextant and VHF ranging–two independent sensing devices–to utilize in these computations. It was not felt that backing this up by use of manual input of range and range rate information obtained by voice from the LM would be particularly valuable especially since the LM can utilize that data in its own computer and transmit all of the maneuvers including CSI and CDH that the command module must execute.
3. In the LM this mode was felt to be unnecessary since that vehicle is equipped with a complete backup system, the AGS, into which manual range data can be input. But probably the strongest argument against the need of manual input of range and range rate in the LM computer is that if the primary guidance system is working reasonable well the state vectors at LM insertion should be good enough even without radar data to permit targeting both the CSI and CDH maneuvers. Of course, conditions following CDH would not be ideal. That is, more than likely the orbits would not be precisely coelliptic and the TPI time would probably have shifted beyond the usual tolerances. However, a precise TPI maneuver based on updated rendezvous naviga- tion will be available from both the AGS and from the command module based on sextant and VHF ranging. In addition to these, there are the backup techniques which utilize whatever useful observational data is available. And, of course, MSFN will provide assistance.
4. Elimination of these rendezvous navigation modes substantially simplifies the spacecraft computer programs–as well as crew proce- dures and training, I suspect–and does not appear to significantly reduce overall onboard capability.