QUESTION:
What kind of energy does the Hubble use, and how long will it last?

ANSWER from Trish Borgman on May 2, 1996:
Well, HST primarily uses solar energy--that's why those two
looooong solar panels are on each side of the telescope.
The panels themselves are pretty fragile, though, so they
will have to be replaced again during the servicing missions.
You may be wondering how HST can run on solar energy all
the time--after all, HST is sometimes in the Earth's shadow
during its orbit.  During these shadow times, HST relies
on batteries.  But, since solar energy is inexhaustable,
it can be used forever!