KFL@MIT-MC.ARPA ("Keith F. Lynch") (12/30/85)
From: sun!amdahl!ems@ucbvax.berkeley.edu (ems)
Would it be possible to 'skip on the surface'? If one
re-enters on a rough tangent, cannot some form of 'aerobraking' be
used to modify the orbit?
No. If part of the orbit is in the atmosphere, the projectile will
keep returning to the atmosphere. In order to get it into a stable
orbit outside the atmosphere, thrust must be applied when outside the
atmosphere. The projectile will in any case keep returning to the
point at which thrust was last applied, whether that is on the ground,
in the atmosphere, or in space.
BTW the discussion on two masses was marvelous, what happens if one
mass is sent up, but divides in two at apogee?
That is what rockets do. The second mass is the expended fuel.
Certainly this will work, but requires a lot of energy. Which is one
of the main reasons why space travel is so expensive.
In theory you could launch a projectile from the ground with an
electromagnetic (or other) gun, and have it fire its rockets to get
into a stable orbit when it reaches a good altitude outside the
atmosphere. The only problems are that the G forces inside the gun
would be very high (enough to kill any astronaut and probably to set
off the onboard rockets prematurely) and the air resistance on the way
up would burn up much of the projectile, take away much of its kinetic
energy, and subject it to high G forces again. Hopefully a gentler
inexpensive way to get into space can be developed.
...Keithhenry@utzoo.UUCP (Henry Spencer) (01/02/86)
> ... The only problems are that the G forces inside the gun > would be very high (enough to kill any astronaut and probably to set > off the onboard rockets prematurely) ... Building rockets to stand it should not be an insuperable problem, given that similar hardware can be (and is) shot from ordinary guns without significant trouble. Building astronauts to stand it is a different matter... -- Henry Spencer @ U of Toronto Zoology {allegra,ihnp4,linus,decvax}!utzoo!henry