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To: wastedyears

Nope- a stable orbit without thrusters must be focused on the centre of the earth, so geosynchronous orbits are only possible over the equator. Satellites that orbit above or below the equator actually cross the equator at an angle twice during each orbit; the angle at which it crosses will be the same as the maximum north and south lattitude over which it will orbit.


32 posted on 07/26/2010 8:48:25 PM PDT by Squawk 8888 (TSA and DHS are jobs programs for people who are not smart enough to flip burgers)
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To: Squawk 8888
Nope- a stable orbit without thrusters must be focused on the centre of the earth, so geosynchronous orbits are only possible over the equator. Satellites that orbit above or below the equator actually cross the equator at an angle twice during each orbit; the angle at which it crosses will be the same as the maximum north and south lattitude over which it will orbit.

Pardon, but a slight quibble with the terminology. An inclined orbit at geosynchronous altitude is still geosynchronous (although noone would call it "geostationary"). From a fixed point on the earth, as you imply, the satellite appears to wander north and south of the equatorial plane. Throw in a slight eccentricity in the orbit, and the north-south deviation becomes a figure eight.

TV stations, along with other geosync satellite users, have to use dishes that are dynamically steered through small angles in alt/azimuth (larger than their beamwidth) to track these satellites.

A friend who had to install a number of ground stations was told by the satellite people that it cost the satellite less station-keeping fuel to have an orbit like that, implying a longer satellite life.

35 posted on 07/26/2010 9:56:19 PM PDT by Erasmus (Personal goal: Have a bigger carbon footprint than Tony Robbins.)
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