On Fri, 28 Dec 2007 07:34:38 -0500, Bob Noel
wrote:

In article ,
"Oz Lander" wrote:

How do you propose to slow the shuttle down from orbital velocity?

That I guess answers my question then. I was not aware that such high
speeds were required to just stay in orbit. What would it take to slow
the shuttle down whilst in orbit, enough to allow it to re-enter at a
slower speed?

They can slow down, but the more they slow down the steeper the
re-entry and the more power it would take to slow them at that stage.
Currently they slow just enough to drop out of orbit. Orbital speed
doesn't let them break free of earth's gravitational field. They are
continually falling around the earth.


It would require a large amount of fuel, way more than we can currently
afford to put into orbit.
Or even have the technology to lift.

Yup. Just think of a take off in reverse. They'd need enough fuel to
do the opposite of the take off which means they'd have to put
everything they now use for a takeoff, into orbit. They'd have to use
many times the fuel they now use to launch that extra weight. Much of
the initial lifting is done with those large solid propellant boosters
so they'd need to launch not only every thing they do now, they'd need
to power to put the shuttle, an external fuel tank, and two boosters
into orbit.

It sorta makes those old sci-fi movies where they used retro-rockets
to land appear in a different light. We don't have that kind of
power...yet. :-))

Roger (K8RI)