Downthread: Invitation for an AAP spacecraft computer program requirements shindig (May 04, 1967)
See listAPR 22 196767-FM1-34FM/Deputy ChiefComputer program requirements for AAP
On April 20 we had a meeting to assemble preliminary spacecraft computer program requirements for AAP missions 1 through 4. This is one step in the process of assembling a program requirements document needed to pro- vide a basis for sensible contract negotiations with MIT and to provide a basis upon which MIT may proceed with preparation of the Guidance System Operations Plan [GSOP]. Personnel from AAPO, MPAD, FBD and C&C were represented. I neglected to include Flight Crew people through some sort of stupid oversight, and I'm very sorry about that. But we will be getting together again, I'm sure.
We did this job in two steps, first by identifying which of the individual processors in the AS-504 LM and command module programs were necessary and which ones could be deleted for the AAP missions. And then we went on to identify, as well as we could, all of the additional unique AAP require- ments which must be added in. We attempted to list programs to support all of the proposed flight operations we know about based on the assumption it would be better to drop them from the list later than to risk overlooking them.
Following is a “required/deleted” list of the AS-504 CMC processors to support AAP 1 and AAP 3. [AAP 1 is a CSM LMSS combination which will ren- dezvous with the AAP 2 SIVB workshop, airlock, and multiple docking adaptor. AAP 3 is a 56-day duration CSM which rendezvous with the AAP 4 LM/Apollo Telescope Mount (ATM) and the AAP 2 SIVB workshop]. Of course, a number of non-mission programs [executive and service types] not listed here must also be carried over. Our preliminary estimate is that these deletions will free up about 5100 words of storage – certainly not an excessive amount.
P00 CMC Idling P07 System Test P01 Prelaunch Initialization P15 TLI Prethrust & Thrust P02 Gyro Compass P17 TPI Search P03 Option Verification P22 Lunar Orbit Navigation P05 CMC Startup P23 Cis-Lunar Navigation P06 CMC Power Down P25 Lunar Landing ���� ������ P11 EOI Monitor P26 LGC Initialization P20 Rendezvous Navigation P32 Lunar Orbit Insertion (LOI) P21 Ground Track P33 Lunar Orbit Plane Change (LOPC)
P27 CMC Update P37 Return to Earth Target (R??) P30 External ΔV P65 Entry Up-Control P31 Lambert Aim Point P66 Entry Ballistic Phase P34 Transfer Phase Initiation (TPI) P70 Safe Perilune Target (RTE) P35 Transfer Phase Mid. Corr (TPM) P77 TPI Search P40 SPS Thrust Maneuver P41 RCS Thrust Maneuver P47 Thrust Monitor P51 IMU Alignment Determination P52 IMU Re-alignment (Sextant) P53 IMU Re-alignment (Backup using Telescope) P61 Entry Maneuver to Separate P62 Entry Sep. Maneuver P63 Entry Initialization P64 Entry Post 0.5 G Phase P67 Entry Final Phase P74 TPI (LM) P75 TPM (LM) R30 Orbit Parameter Display R31 Rendezvous Parameter Display R32 Target ΔV
The following capabilities may be retained, modified or added in the CM program processors noted above.
1. Digital Autopilots:
a. A digital autopilot(s) is required to control RCS translation and attitude maneuvers for the following vehicle configurations:
(1) CSM alone (2) CSM with LMSS attached (3) CSM with LM/ATM attached (4) CSM with cluster(s)
b. A digital autopilot(s) to provide thrust vector control (TVC) of the SPS engine is required for translational maneuvers of the following vehicle configurations:
(1) CSM alone (2) CSM with LMSS attached (3) CSM with LM/ATM attached
c. A special digital autopilot may be required to control the command module RCS during the firing of the solid retrorockets, if they are provided for a backup deorbit capability on the AAP 3 command module.
2. The following capabilities are required in support of the AAP 1 mission flight operation:
a. Local vertical hold mode utilizing the RCS digital autopilot for the CSM with LMSS attached.
b. The capability to compensate for the actual alignment of the LMSS [and other components which make up the over-all cluster] with the command module “nav base” in order to provide attitude control of them.
c. A landmark sighting routine utilizing the sextant.
3. Additional requirements to support AAP 3:
a. As a result of the severe Saturn payload constraint, it may be necessary to provide guidance to the SPS engine serving on a third stage of the launch vehicle to get into orbit. If this does become a nominal part of the mission, as opposed to Contingency Orbit In- sertion previously considered for main line Apollo, it will probably be necessary to also include some processing and displays to support crew backup procedures and abort procedures.
b. If a rendezvous radar is added to the command module, it will prob- able be desirable to utilize its observations in the rendezvous navigation processing. This could be in addition to or in lieu of sextant observations.
c. Special preferred alignment programs are almost certainly required in support of various experiments to provide unique attitude hold capabilities and/or attitude time history profiles.
d. Special solid retrorocket sequence to assist in attitude control during and after their firing may be necessary.
e. New telemetry downlists will be required.
f. Auto optics search and gimbal lock avoidance – programs deleted from the main line Apollo programs – may be restored to the program for AAP if storage permits.
g. Since the command module has been assigned the task of many complex operational rendezvous, it may be desirable to add the onboard capability of targeting the nominal rendezvous maneuvers [CSI and CDH] – programs we have deleted as unnecessary from the AAP 4 LM program. Storage probably will not permit this 1200 word addition which is certainly not mandatory.
h. Some inflight test programs may be desirable to check out the guidance system prior to its use following extended powered down periods.
i. Reconsideration is being given to including an automatic [rendezvous] braking capability.
��������� to a list of “required/deleted” AS-504 LM programs for use on AAP ���������������� preliminary criteria is that those deletions will ��� ������������������� of storage.
P00 LGC Idling P07 Systems Test P01 LGC Initialization P10 Predicted Launch Time (CPP) P02 AGS Initialization P11 Predicted Launch Time (TPI) P05 LGC Startup P12 Powered Descent Guidance P06 LGC Power Down P17 TPI Search P20 Rendezvous Navigation P22 RR Lunar Surface Navigation P21 Ground Track Determination P32 CSI Prethrust P25 Preferred Tracking Attitude P33 CDH Prethrust P27 LGC Update P36 TPF Maneuver P30 External ΔV Prethrust P40 DPS Thrust Prog. P31 General Lambert P42 APS Thrust Prog. P34 TPI Prethrust P55 Lunar Surface Align (Normal) P35 TPM Prethrust P56 Lunar Surface Align (Backup) P41 RCS Thrust Prog. P57 Any Time Launch Align P47 Thrust Monitor P60 Predicted Lunar Land. Time P51 IMU Orientation Determination P61 DOI Maneuver P52 IMU Realign P63 Landing Braking P53 IMU Realign (Backup using LPD P64 Landing Approach reticle) P65 Landing (Auto) P74 TPI (CSM) P66 Landing (ROD) P75 TPM (CSM) P67 Landing (Manual) R30 Orbit Parameter Display P70 DPS Abort R31 Rendezvous Parameter Display P71 APS Abort R32 Target ΔV P72 CSI (CSM) P73 CDS (CSM) P76 Transearth Inject (TEI) Backup
Since the LM will be equipped with neither a Descent Propulsion System [DPS] not an Ascent Propulsion System [APS], it is also possible to delete three AS-504 LM digital autopilots completely – namely, the APS, DPS and the command module-LM docked DPS [so-called SPS backup].
The following capabilities may be retained, modified or added to the LGC processors listed above:
4. RCS digital autopilots for control of translation and attitude maneuvers in the following vehicle configurations:
a. LM/ATM, with solar arrays both extended and retracted
b. LM ascent stage only [if it is possible to jettison the ATM.]
c. LM/ATM with CSM attached, with solar arrays both extended and retracted.
d. LM when docked to the cluster.
5. ����� special ��� processor requirements ������. �������������� ��������:
a. New telemetry downlists will be required.
b. Restoration of gimbal lock avoidance.
c. Some inflight test programs may be desirable to check out the guidance system prior to its use following extended powered down periods.
d. The MSFC is currently studying the desirability of utilizing the LGC to support their ATM and control moment gyro requirements as opposed to providing their own computer and/or special electronics. If they determine the LGC should be used they will document their requirements.
e. Reconsideration is being given to including an automatic rendezvous braking capability.
It is anticipated that within a month, a more formal spacecraft computer program requirements document will be distributed by the Flight Software Branch of the Flight Support Division. It will incorporate the results of action items assigned to various MSC elements at this meeting, such as:
1. The more precise definition of DAP requirements, which is the responsi- bility of GCD [Cox/Line].
2. Definition of the special preferred attitude program requirements in support of experiments, assigned to MPAD [Hunt].
3. The detailed requirements for the LMSS mission, assigned to AAPO and MPAD [Ernull].
4. Definition of the solid retro sequence requirements, assigned to MPAD [Weber].
5. The reconsideration of automatic braking, assigned to GCD [Klinar].
The purpose of distributing this memorandum is to inform you of what is going on in this area as well as to solicit your comments. We are partic- ularly interested in being informed of omissions and would appreciate your assistance in providing more detail in the definition of the items above.