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Old October 4th 11, 03:22 AM posted to sci.space.tech
byblow
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Posts: 9
Default SpaceX fully reusable launcher

I'm curious about the first-stage landing technique. The video doesn't
show a a nose-first reentry for the first-stage, but as dglow astutely
noticed, the front of the first-stage appears to have a heat shield
that can handle the second-stage exhaust at separation.

After separation, the first stage flips over and fires three of its
nine engines to begin reentry (I wonder what altitude the stage will
reach?). It's next shown descending tail first, possibly with just the
center engine firing. The landing struts begin to deploy, rotating
downward from a 12 o'clock position, to roughly 5 o'clock and 7
o'clock positions by touchdown. The landing struts appear rather wide,
perhaps for extra drag during final descent. I wonder if they're
thinking about using aerodynamic flaps as well?

My guess is the first-stage does a nose-first reentry like the second-
stage, flips over and goes into free fall during most of its descent
through the atmosphere, perhaps using the RCS at the top of the stage
to control its attitude. I'm curious about what altitude SpaceX
envisions firing the center engine for final descent and landing. I
assume only one engine is needed because most of its fuel is spent,
and the second-stage and Dragon are absent.

The Wiki article about the DC-X notes that if it could reach orbit, it
would make an ideal craft for landing on the moon or Mars, the latter
of which is Musk's ultimate goal. Perhaps he has visions of using the
second stage as a Mars cargo lander to complement the Dragon-derived
Mars people lander. He might need a fuel depot in earth orbit for
such a scheme.

Wiki: "Had a DC-type craft been developed that operated as an SSTO in
Earth's gravity well, even if with only a minimum 4-6 crew capacity,
variants of it might prove extremely capable for both Mars and Moon
missions. Such a variant's basic operation would have to be
"reversed"; from taking off and then landing, to landing first then
taking off. Yet, if this could be accomplished on Earth, the weaker
gravity found at both Mars and the Moon would make for dramatically
greater payload capabilities, particularly at the latter destination."