# Re: More GEO questions

From: Bjoern Gimle (b_gimle@algonet.se)
Date: Fri Oct 12 2001 - 14:33:48 EDT

• Next message: Bjoern Gimle: "Re: NOSS"

```I think Bill missed a crucial point, mentioned only briefly:
We are talking about normal satellites staying in a "fixed" orbit without
using any fuel - not a Buck Rogers type starship. Such an orbit is defined
by the position and speed at a SINGLE moment. If the speed is correct, and
perpendicular to the radius, it is a circle, and has a resulting period. If
it is lower, the period and perigee (closest point) is smaller, unless the
decrease is exactly at the perigee. If higher, the period and apogee is
higher, unless the increase is exactly at apogee. If more than 1.414...
times the circular speed, it will escape Earth gravity. If very low, what
perceive as a "parabola of throw" (?) is the tip of a very narrow ellipse,
with a perigee near the Earth's centre. To keep a 24h period closer to
Earth, it would have to hover like a VTOL aircraft, farther away it would
reverse the thrust to counteract the centrifugal force.

So, the formulae that have appeared are ONLY valid for the standard
geostationary orbit.

Arthur C. Clarke did not invent this formula, or those that describe other
"free-flight" orbits, they have been known since the days of Newton. But he
was the first to realize how they could be used for communication
satellites.

-----------------------------------------------------------------
Unsubscribe from SeeSat-L by sending a message with 'unsubscribe'
in the SUBJECT to SeeSat-L-request@lists.satellite.eu.org
http://www.satellite.eu.org/seesat/seesatindex.html
```

This archive was generated by hypermail 2b29 : Fri Oct 12 2001 - 14:38:32 EDT