Geosynchronous GPS?

"Ultimate Buu" writes:

Wouldn't it be prudent for the U.S. to develop a GPS-like system which is
based in a geosynchronous orbit, as both the Chinese and Russians are
developing ASW (anti-satellite warfare) systems? At the very least such a
system should be used as a backup since most precision weapons rely on GPS.
It would be much harder for the Chinese to knock out a geosynchronous
satellite and it would be almost impossible to do so using lasers (their
preferred method at this time).


Were you under the impression that GPS was in LEO?

GPS is not in GEO, because it doesn't need that specific orbit and
because that's a crowded bit of real estate and frequency space as is,
but it is in a very high sub-GEO orbit not likely to be reached by
first-generation antisatellite weapons. And anything that *can* reach
GPS, can almost certainly reach GEO as well.


--
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*Member:AIAA,NRA,ACLU,SAS,LP * is worth doing for money" *
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difficult to get service at high latitudes.


"Ultimate Buu" wrote in message
...
Wouldn't it be prudent for the U.S. to develop a GPS-like system which is
based in a geosynchronous orbit, as both the Chinese and Russians are
developing ASW (anti-satellite warfare) systems? At the very least such a
system should be used as a backup since most precision weapons rely on
GPS.
It would be much harder for the Chinese to knock out a geosynchronous
satellite and it would be almost impossible to do so using lasers (their
preferred method at this time).

Ultimate Buu wrote:
Wouldn't it be prudent for the U.S. to develop a GPS-like system which is
based in a geosynchronous orbit, as both the Chinese and Russians are
developing ASW (anti-satellite warfare) systems? At the very least such a
system should be used as a backup since most precision weapons rely on GPS.
It would be much harder for the Chinese to knock out a geosynchronous
satellite and it would be almost impossible to do so using lasers (their
preferred method at this time).


Sounds like this would merely lead to development of better sattelite
knockout weapons... This planet definately doesn't need yet another
dumb arms race.

--
Sander

+++ Out of cheese error +++

On Mon, 4 Aug 2003 11:05:23 +0200, "Ultimate Buu"
wrote:

Wouldn't it be prudent for the U.S. to develop a GPS-like system which is
based in a geosynchronous orbit, as both the Chinese and Russians are
developing ASW (anti-satellite warfare) systems? At the very least such a
system should be used as a backup since most precision weapons rely on GPS.
It would be much harder for the Chinese to knock out a geosynchronous
satellite and it would be almost impossible to do so using lasers (their
preferred method at this time).

The GPS constellation is at about 12,000 miles altitude... half-way to
GEO. They're not going to get much safer than where they are now.

Brian

On Mon, 4 Aug 2003 11:05:23 +0200, "Ultimate Buu"
wrote:

Wouldn't it be prudent for the U.S. to develop a GPS-like system which is
based in a geosynchronous orbit,

I assume you meant "geosynchronous" in contrast to "geostationary,"
i.e. a 24-hour orbit vs. a circular 24-hour orbit over the Equator.
You might have trouble with the geometry if all the GPS sats orbited
in a single plane; I think that a lot of the positions indicated would
be ambiguous. The GPS sats will have to be in highly-inclined orbits.

Also, geostationary orbit has always seemed to me to be exceptionally
vulnerable. Just put a couple of kilos of gravel in the same orbit but
going the other way, and pretty soon no comsats.

Bob Munck

John Schilling wrote:
"Ultimate Buu" writes:


Wouldn't it be prudent for the U.S. to develop a GPS-like system which is
based in a geosynchronous orbit, as both the Chinese and Russians are
developing ASW (anti-satellite warfare) systems? At the very least such a
system should be used as a backup since most precision weapons rely on GPS.
It would be much harder for the Chinese to knock out a geosynchronous
satellite and it would be almost impossible to do so using lasers (their
preferred method at this time).



Were you under the impression that GPS was in LEO?

GPS is not in GEO, because it doesn't need that specific orbit and
because that's a crowded bit of real estate and frequency space as is,
but it is in a very high sub-GEO orbit not likely to be reached by
first-generation antisatellite weapons. And anything that *can* reach
GPS, can almost certainly reach GEO as well.




It is crowded and they would rather not have a lot of non-planar
satellites wandering around. They would rather distribute them around
so as to lessen the Geometric Dilution of Precision.

On Thu, 07 Aug 2003 15:20:08 -0400, Robert Munck wrote:
Also, geostationary orbit has always seemed to me to be exceptionally
vulnerable. Just put a couple of kilos of gravel in the same orbit but
going the other way, and pretty soon no comsats.

You'd have to be mighty lucky to hit even one comsat by doing that.
They aren't exactly strung out on a wire. A comsat doing good station
keeping could be anywhere in a cubic mile volume around the ideal
GSO track. Those who are in fuel conservation mode describe daily
figure 8s which cover a much larger span (roughly +/- 400 miles North
South). Meanwhile, a comsat only presents a few square meters of
cross section along the orbital track. Even a couple of kilos of fine
sand would have a hard time providing a dense enough pattern to
have more than an infinitesimal chance of hitting one in a year.

Gary

"Ultimate Buu" wrote in message .. .
Wouldn't it be prudent for the U.S. to develop a GPS-like system which is
based in a geosynchronous orbit, as both the Chinese and Russians are
developing ASW (anti-satellite warfare) systems? At the very least such a
system should be used as a backup since most precision weapons rely on GPS.
It would be much harder for the Chinese to knock out a geosynchronous
satellite and it would be almost impossible to do so using lasers (their
preferred method at this time).

As mentioned, there half way to GEO (energetically, almost all the way
there).

Another defence would be to have secret, dormant GPS satellites (in a
stealth shroud?) which would activate if other ones were knocked out.

I wonder if they have that already?

On Mon, 11 Aug 2003 04:50:49 -0400, Gary R Coffman
wrote:

... Just put a couple of kilos of gravel in the same orbit but
going the other way, and pretty soon no comsats.

You'd have to be mighty lucky to hit even one comsat by doing that.
... A comsat doing good station keeping could be anywhere in a
cubic mile volume around the ideal GSO track. ... a comsat only
presents a few square meters of cross section along the orbital
track.

Not by my figures. If there are only 1,000 pieces of gravel and
a given comsat takes up 1/1,000,000th of the (one-mile cross-
section of the) orbital track, you've about one chance in 1,000 of
hitting it. But the gravel is moving through the entire GSO track
twice a day (at 6 km/s relative) so it has a good chance of
hitting one comsat every day or two and all of them within a year
or two. I think the probabilities are actually higher than that.

Bob Munck

On Wed, 13 Aug 2003 15:48:46 -0400, Robert Munck wrote:
On Mon, 11 Aug 2003 04:50:49 -0400, Gary R Coffman
wrote:

... Just put a couple of kilos of gravel in the same orbit but
going the other way, and pretty soon no comsats.

You'd have to be mighty lucky to hit even one comsat by doing that.
... A comsat doing good station keeping could be anywhere in a
cubic mile volume around the ideal GSO track. ... a comsat only
presents a few square meters of cross section along the orbital
track.

Not by my figures. If there are only 1,000 pieces of gravel and
a given comsat takes up 1/1,000,000th of the (one-mile cross-
section of the) orbital track, you've about one chance in 1,000 of
hitting it.

You're implicitly assuming that the gravel is randomly distributed.

But the gravel is moving through the entire GSO track
twice a day (at 6 km/s relative) so it has a good chance of
hitting one comsat every day or two and all of them within a year
or two.

You're implicity assuming the gravel randomly changes squares
each orbit.

Neither of those assumptions can be taken as a given.

Gary