(KFH) wrote in message ...
I have been thinking about a concept for a remote sensing satellite where
the satellite in LEO would be in an orbit that always passed over the same
ground track every orbit. The purpose would be for multiple daily
observations of one specific area.
I have been told that such an orbit is not stable and without using a lot
of fuel it would drift off of the ground track. Is that true? Or can
there be a stable orbit of this nature?
Thanks
Fred

There is something called a sun-synchronous orbit. You only get one
pass over your target area per day, but it happens at the same time
each day. You end up with a pretty elliptical orbit at around 97
degrees inclination. A completely-LEO orbit (mostly circular) with a
continuous grounnd track is only possible with an orbit directly over
the equator. Otherwise, the rotation of the earth and nodal
regression will throw you off.