# Re: Newbie GEO question

From: Lloyd Thomson (thomson@aros.net)
Date: Thu Oct 11 2001 - 16:31:16 EDT

• Next message: Barker, Jefferson (JBARKER): "RE: Newbie GEO question"

```Actually what happens is that as the speed increases, the orbital height
increases. If you take the speed that a LEO travels at, and impose it on a
GEO, the GEO will reduce its altitude until it reaches a LEO orbit. Works
the same if you impose a GEO speed on a LEO.

Not so simple physics determines the altitude from the speed. Basically what
happens is that all the forces (earth's gravitational pull, circular
momentum of the satellite, and many others) on the satellite will equal out,
and that will determine the orbital characteristics.

The flight patterns of the launch vehicle determine the orbit shape. For
example, some will simply go straight up, then tip over and burn to reach
the final orbit velocity (orbit insertion). Others will go up and then have
several maneuvers to achieve the desired orbit. To reach GEO, lots of them
will go into what they call a transfer orbit, and then maneuver out of that
one into their assigned location.

Orbital mechanics is a well known, but complex field. I freely admit to not
being an expert. I only build the birds that get there.

Later

Lloyd Thomson
OSSS
www.osss.com
lloyd.thomson@osss.com

----- Original Message -----
From: "Bill Mitchell" <escape@velocity.net>
To: "SeeSat" <SeeSat-L@satobs.org>
Sent: Thursday, October 11, 2001 12:53 PM
Subject: Newbie GEO question

Greetings,

I'm new to the list and have a question regarding GEO sat's.
At what speeds do they travel?
I realize that relative to the earth at 22,000 miles they travel 0, but
let's say bring their orbit down to LEO, how fast would they be traveling?
17,500?
I was able to observe one in my homemade 10" telescope, very cool. Stars
move, Satellite doesn't.

Bill
www.velocity.net/~escape

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