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Re: NASA to announce undeserving shuttle winners today

Posted by WillD on Tue Apr 12 22:54:00 2011, in response to Re: NASA to announce undeserving shuttle winners today, posted by johnl on Tue Apr 12 21:34:45 2011.

Unfortunately there isn't a whole lot being reused from the Apollo program. SpaceX's early animations of a crewed Dragon showed an Apollo-like tractor style launch abort escape system which gave the rocket a very Mercury/Redstone look. But their most recent releases indicates they'll use a liquid fueled pusher escape system which can also be used to provide on-orbit maneuvering and propulsive landing capabilities. It is possible a manned Dragon capsule will only return to dry earth, perhaps with a pinpoint landing in the California or Nevada deserts. But that outcome would likely require some testing, and chances are they'll fly the first few manned Dragons with parachute landings and the (highly toxic) hypergolic fuel for the LAS being jettisoned sometime before landing.

The Orion Capsule will use an Apollo-like tractor LAS, but it had to be designed to clear the debris field of an SRB. It turns out that when you abort a large solid rocket by blowing open its case with a massive 'unzipper' shaped charge running the length of the propellant chamber the fuel inside fragments into thousands of burning granules, some of which continue along the flight path. An Orion capsule's LAS may have pulled it clear of the explosion of its Ares I booster, but by the time the parachute deployed it might have been right back within that debris cloud of flaming aluminum perchlorate, which would pretty well destroy the parachutes and doom the crew. As a result the Orion's LAS is tremendously more powerful than the Apollo capsule's LAS, and will likely end up being quite overpowered for whatever vehicle it is finally fitted to, be it the heavy variants of the Delta IV, Atlas V, or Falcon 9, or the medium variant of the Space Launch System.

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