"Gene Storey" wrote in message news:B0qFb.3428$6l1.2442@okepread03...
"Arie Kazachin" wrote

If memory serves, that was the reason that SR-71 had been
returned to service few years before being retired finally (at least,
so far): sats were not flexible enough (remember, you can't refuel
them and changing orbit takes LOTS of fuel).

It was forced on the USAF by Congress. The USAF wanted to spend the
money on more important stuff (like dormitories to get the enlisted troops
off the economy, and off of welfare).

You may not be aware, but most recce sats are nuclear powered, and the
fuel to scoot them around does not have to be combustible.

I do not know of any nuclear power _propulsion_ systems in present
use. Even if there were, it would still have to throw something
away from the vehicle to get momentum which means eventually it
woudl run out of whatever it was throwing away.

Even a cursory understanding of physics would lead you to conclude
that satellite-based recon is scheduled for when the vehicle will
pass over the target, and satellites are not manouvered on a
target by target basis. Manouvering is done for station keeping,
that is to keep the vehicle in it's desired orbit. For a narrow
FOV instrument one presuems that attitude control will be used
to capture the right target area when passing close enough.

My experience is with civilian satellites, or rather with joint
civilian/DOD vehicles like GEOSAT, but physics is physics.

--

FF