This note is in response to your query regarding the “quick return” capability being provided in the lunar module (LM) for aborts during the lunar descent phase. As you recall, I reported deletion of a program in the LM computer for generating coefficients to be used in an abort polynomial to retarget the LM powered…
Category: Descent abort
Current status on the LM DPS engine gimbal caution light problem
This memorandum is to report the results of a very brief investigation into the adequacy of the LM Descent Propulsion System (DPS) engine gimbal caution light. Briefly, this light comes on if a difference between the gimbal drive signal and the gimbal response signal from the Y or Z axis trim malfunction logic is sensed….
AGS/PNGCS incompatability review – Chapter One
At the January 8 meeting of your CCB I was given the action item of reviewing AGS SCP’s Nos. 34 and 35. Specifically, I was to determine our position on the advisability of making these changes which you tentatively approved at that meeting, and, in particular, we are to satisfy ourselves that the AGS and…
Spacecraft computer programs controlling DPS throttling need more changes
On February 14 we had a meeting with everyone at MSC, plus MIT and Grumman, who are interested in the way the spacecraft computer program throttles the Descent Propulsion System (DPS). There has been concern that the throttling programs as currently designed are not adequate for the Descent Orbit Insertion (DOI) maneuver on a lunar…
Lunar rendezvous abort summary
A great deal of work has gone on over the years on the subject of lunar abort rendezvous, spearheaded by Morris Jenkins, Ed Lineberry, Buzz Aldrin and others. The results of some of this work have already been documented and more detailed reports are in the works. The primary reason I’m writing this note is…
Aborts from powered descent on the lunar landing mission
We spent the entire May 8 Ascent Data Priority meeting discussing mission techniques associated with aborts from powered descent on a lunar landing mission. This discussion led to some pretty simple procedures which are outlined in this memo. They are based on some assumptions which I’ve also listed below. If you feel that they are…
Spacecraft computer program – things dealing with lunar descent and aborts from it
I spent an interesting morning at MIT on May 16 with George Cherry, Dan Lickly, Norm Sears, and Craig Schulenberg talking about Luminary how it works and some things that really haven’t been defined yet. It primarily dealt with lunar descent and aborts from lunar descent….
PGNCS Alignment During Hohmann Transfer
The attached IOC presents an analysis which estimates the increase in the probability of an unsafe AGS abort if the PGNCS alignment during Hohmann transfer is not performed. The analysis shows that given that PGNCS fails, the probability of an unsafe AGS abort from hover is increased by less than 0.001……
AGS Performance with no PGNCS Alignment During the Homann Transfer (Task 46)
There is some concern about the capability of the AGS to safely perform an abort from hover without a PGNCS alignment during the Hohmann transfer. This concern stems from the results of Monte Carlo analyses which indicate that the mean minus three sigma for perilune altitude of an AGS controlled abort from hover is less than 30,000 feet (the safe orbit limit), and from single error analyses which indicate that an initial misalignment slightly larger than three sigma results in an unsafe orbit……
LM Descent abortability computation is proposed
Ed Copps of MIT attended one of our mission techniques meeting recently during which we discussed the use of the LM Descent Propulsion System low level sensor light. This is the light, you recall, which comes on when approximately 30 seconds worth of propellant is still available at full thrust or two minutes at 25%…