Questions and Answers
EARTH RETURN ABORT CAPABILITIES
Speaker: Ronald L . Berry
1.Dr. Rees - Why not use the APS for a backup propulsion system?
ANSWER - Since the ascent engine is not gimballed, the possible c.g. offset effects cannot be controlled.
2.What is the RCS engine burn time limitation?
ANSWER - Specifications limit is 1000 seconds.
3.Dr. Mueller - Have methods to restart the SPS engine in the event of an early shutdown during transearth injection burn been investigated?
ANSWER - If the problem is a guidance or control problem, the engine can be restarted and controlled manually the problem is with the SPS engine itself, nothing can be done. This is one of the accepted risks in the program.
4.Dr. Haeussermann - Have we looked into using a DPS-SPS combination?
ANSWER - No. The main reason for using the DPS as backup is because of an SPS failure.
5.Mr. Richter - Can't we use ADS some of the time - isn't it load dependent?
ANSWER - The control authority is marginal in most cases for the APD since the APS engine is not gimballed.
6.Mr. Richter - Can we use two SPS burns for fast earth return transfer?
ANSWER - This is being looked into. This may not be a desirable way to achieve a gain in return time, since it could be dangerous. If the SPS did not fire the second time, you might exceed acceptable entry velocity or conditions.
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