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Originally Posted by KingNor
i'm not terribly knowlegeable about this stuff, but to me, it
seems pretty obvious that a rocket punching strait up, and then
straight to the moon would have to be MUCH bigger than say.. a
rocket that launches into orbit, then uses gravity and such to
slingshot its speed up to escape velocity.
wasn't that what the S5 designer was talking about? you can't
fly straight there, so you fly in a round about way.
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No, there's no reason a rocket can't launch directly
to the Moon, and there's no saving in going into orbit first.
The Apollo spacecraft went into orbit to be sure everything
was working okay before committing to a minimum 3-1/2 days
away from Earth. And perhaps to make the exact time of launch
less critical. The time for translunar injection from Earth
orbit could be determined much more precisely, because it
didn't involve as many uncertain factors as launch from the
ground through the atmosphere.
I think that three spacecraft have used gravitational tricks
to reach the Moon, two of which were powered by ion engines.
They slowly spiralled away from Earth, were captured by the
Moon's gravity, then slowly spiralled into lower, circular
orbits. Another was a spacecraft which wasn't originally
intended to go to the Moon, but which used the Sun's gravity
to help get it from high Earth orbit to lunar orbit.
-- Jeff, in Minneapolis