Thanks Steve.
Yes this was a learning thing for me. I knew all about the Geosynchronous I thought. But i guess my thinking was actually Geostationary. Even after 30+ years playing with these birds I never thought of a Geo sync that moved he he he.
Joe WB9SBD Sig The Original Rolling Ball Clock Idle Tyme Idle-Tyme.com http://www.idle-tyme.com On 6/13/2013 8:26 PM, Stephen Melachrinos wrote:
Joe -
You used two different terms here, and there's a distinction that helps with the explanation.
A "geosynchronous" satellite is one whose orbital period is one sidereal day. This makes its orbit track (on the earth's surface) repeat day after day. A "geostationary" satellite is a special case of geosynchronous that is truly stationary with respect to the earth. This means that not only is its orbital period one sidereal day, but its inclination and eccentricity are zero. (This requires regular orbit adjustments, typically referred to as north-south stationkeeping and east-west stationkeeping.) From your description ("a good amount of vertical drift"), Terrestar is geosynchronous but not geostationary.
Unfortunately it's not always obvious which is meant when we describe a satellite with the shorthand term "Geo." Furthermore, some satellites start out as geostationary and end up becoming simply geosynchronous when the owner decides to (or has to) skip the stationkeeping maneuvers (e.g., to save fuel).
Steve W3HF On 06/13/13, Joe[email protected] wrote: <snip> It's a Geosynchronous communications satellite.
<snip>And thats where we also got messed up, the Geo bird is more or less Stationary in the sky. It has a pretty good amount of vertical drift tho. it's orbital period makes it Geo Stationary. but it has a pretty high inclination so it drifts up and down in declination some.