The orbit altitude of an object is determined by its rotational speed
above the earth.  If you want a higher orbit, start spinning around the
earth faster, lower, slow yourself down.  A space station like MIR was
at a very low orbit to begin with, and its size would make it so it
could orbit much further from the earth than any satellite and still
orbit earth (ie, not break away).

The reason they dropped it was because they had just barely enough fuel
since this last cargo ship to brake it enough (while still under their
control) to drop out of orbit.  It would have taken significantly more
fuel to speed it up enough to get it out of earth orbit, not to mention
that if they didn't make it it might start doing an elliptical orbit,
and becoming more hazardous than it was when it just occupied its own
orbit.

They didn't have enough money to send up another freighter, and if they
waited too much longer the fuel would have been used up just keeping it
in its current orbit (so it doesn't hit anything else, drift higher or
lower, and has a predictable path - critical in space)

-Adam

(actually, I'm just sending this to make sure my cable modem's smtp
server is working...  Yay for broadband!  And birthdays!  And loving
wives!  Yay!)

Jinx wrote:
>
> I've heard the question asked several times but never an answer
>
> Why is so much trouble being taken to crash Mir when it seems
> possible to send it out of orbit away from Earth ? Is it just a
> question of fuel ? There've been many cargo trips to Mir, just
> wondered why they didn't do it that way
>
> Thought I'd better ask now as there's only an hour before the old
> rustbucket's due over NZ and well, you never know. Although the
> planned braking bursts are said to be going OK and on schedule
> so no one's kacked their dacks yet about an unexpected visit
>
> --
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