Re: What was the launch window for a moon shot?

mmaker@xxxxxxxxxxx wrote:
On Jun 23, 4:26 am, Orval Fairbairn <orfairba...@xxxxxxxxxxxxx>
wrote:
I do know that a direct ascent trajectory had only about a 3-minute
launch window, which is why it was not planned into the missions.

Presumably the launch to parking orbit was more down to a desire to check out the spacecraft before committing to the Moon? If there was
a major fault (e.g. an air leak somewhere which couldn't be fixed, or
multiple fuel cell failure) then they could rapidly return to Earth from the parking orbit, whereas if they launched on a direct ascent
to the Moon they'd take quite a while to get back even with a direct abort using the SPS.

As others have noted, you're both right. Apollo hung around in LEO for
~1.5 revolutions so that the spacecraft could be checked out. Otherwise, one could do TLI after coasting in a parking orbit for as
little as, say, a third of a revolution. In both cases, doing two burns
- one to reach orbit and one to escape orbit - gave a much longer launch
window.

It's all explained at http://en.wikipedia.org/wiki/Parking_orbit

--
Dave Michelson
davem@xxxxxxxxxx

.

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