Chair Force Engineer

Tuesday, April 10, 2007

Solid Support?

In announcing its memorandum of understanding with United Launch Alliance, SpaceDev revealed that it's willing to fly as many as three solid rocket boosters on the Atlas V that could possibly take the Dream Chaser spacecraft to orbit.

SpaceDev is not the first firm to advocate the use of an Atlas V with solid rocket boosters for manned spaceflight. TeamVision also proposed an Atlas V with four SRB's as a booster for the Orion spacecraft, eliminating the need for an expensive Ares I development program.

Lockheed Martin seemed to have ruled out the use of SRB's when conducting its man-rated Atlas V study. The reasoning was that NASA's specs for safety factors in human spaceflight were exceeded when the additional thrust and impulse of the SRB's was accounted for. Lockheed Martin concluded that only the single-core Atlas V's were suited for manned spaceflight.

The SpaceDev vehicle gets around the NASA safety regulations because it's developed and operated by a private entity. It remains to be seen whether the FAA will hold an orbital space tourism firm to the same standards as NASA.

At the same time, the NASA safety factors should be open to debate. As the TeamVision report argues, the safety factors on an Atlas V 551 were sufficient for an expensive, unmanned spacecraft like New Horizons. Is there any reason why a manned spacecraft with a robust abort system couldn't fly on the same launch vehicle? I suspect that the Redstone, Atlas and Titan II rockets would not have met NASA's current safety standards, either. Yet they worked well when they were employed in a total of sixteen manned spaceflights.

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