Re: our first images of the ASTRA satellite cluster AND NOSS angular separation

From: Bjorn Gimle (
Date: Sat Jun 15 2002 - 16:21:57 EDT

> Normally, I thought, geostationary satellites have fixed positions. The
> pictures are at
> ...

Subject: NOSS angular separation
> ...
> Another question---are they all equidistant or are two much closer

Geostationary satellites are not "fixed",  they are following an orbit near
the equator. To appear fixed, the orbit must be perfectly circular, and have
the same period as the Earth's rotation. But any orbit is perturbed by Moon,
Solar radiation pressure (SRP), Asymmetric gravitational field of the Earth
... ..., and must be corrected occasionally to remain close to the ideal.

The same goes for NOSS. If they were maintaining constant distances (not by
constant engine power, like StarTrek) they would at any one instant have
equal speeds and "parallell" directions. This could work for the
leader/trailer, but the "outlier" will have a different inclination, and
intersect the orbit of the others near the equator.

The outlier is normally closer to the leader.

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