26. Lesson: Provide Excess Consumables
Design the systems on any spacecraft for a maximum of expendables and consumables. Assure that the quantities of these expendable items exceed those necessary for the design mission by a wide margin.
The electrical power and attitude control gas of Skylab exceeded the normal mission requirements. Without this excess, it would have been impossible to save the program since it was the excess which permitted the unmanned activities to be conducted which saved the mission.
As an example of the benefits which can be derived from excess consumables, the question of how much hydrogen and oxygen should be loaded on the CSM for the fuel cells was raised in 1972. A Level 1 decision was made that the CSM would be fully loaded with cryogenics and a water storage tank would be provided to permit the fuel cells to provide power for 10-14 days. (The water tanks stored the water generated and prevented contamination of the instruments.) With the failure of the workshop solar array at launch, that power became mandatory until Astronauts Conrad and Kerwin released the jammed array.
These lessons learned are from SKYLAB LESSONS LEARNED AS APPLICABLE TO A LARGE SPACE STATION, A dissertation submitted to the faculty of The School of Engineering and Architecture Of the Catholic University of America For the Degree Doctor of Engineering by William C. Schneider, Washington, D.C., 1976.
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