[amsat-bb] Re: sirius orbit name?
rmann at latencyzero.com
Thu Feb 21 13:19:51 PST 2008
On Feb 21, 2008, at 10:29 AM, Jim Jerzycke wrote:
> The Sirius birds are in an "Inclined Orbit".
> It's explained more in the WikiPedia entry, about half
> way down the page.
What I read says it's in a "geosynchronous highly elliptical" orbit.
Strictly speaking, you can't have a truly geosynchronous orbit that's
elliptical (it must be circular). It must also have an inclination of
But: the inclined elliptical orbit causes the satellite to speed up
relative to Earth's rotation during parts of its orbit, and slow down
during others. This is what causes the East-West motion of the figure-
eight. The inclination is what gives the North-South motion. The two
are combined in such a way as to give a nice figure-eight pattern over
the surface of the Earth.
The Wikipedia entry refers to this as a "Tundra Orbit":
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