Chair Force Engineer

Thursday, March 09, 2006

The Ambiguously-Shaped Capsule

When I first posted on SpaceX's "Dragon" capsule, I jumped to the conclusion that it would make a nose-first reentry like CORONA and the t/Space CXV. After reading some comments on Selenian Boondocks, I'm not so sure.

Because there is no docking hatch in the base of the gumdrop-shaped capsule, there is no reason why Dragon couldn't reenter base-first. Even if there was a hatch, a reentry could still be successful, as proven by the reflight of the Gemini 2 capsule.

Still, I am inclined to think that it makes a nose-first reentry. Why do I suspect that? Because Dragon (in the next-to-last illustration on this page from Spaceref) retains its nose cap on a hinge instead of discarding it. It tells me that it will need to shield the berthing mechanism during reentry. This was not necessary on Apollo and other capsules that made a base-first reentry.

This leads to an interesting possibility: could Dragon be designed to reenter in both base-first and nose-first attitudes? This would create a lot of new challenges, like the need for two sets of parachutes, or at least a parachute that could deploy in both orientations. But it would ensure that reentry was a lot safer if you could make a stable ballistic reentry from a wide range of spacecraft orientations.