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Re: [APML] OT: Satellite Tracking (was OK What the He** isit??)
range data is nice but pretty irrelevant, you can have 2 data points with range, az, and el andtry to do an orbit or you can have just av and el for 3 points to do an orbit. of course the more data points over time, the better the orbit. some stuff is more closely watched than others.
film cameras were shut down in early 1984.
most RADAR data is on relatively near earth stuff. errors increase with distance, plus you can do better identification on RADAR for near earth. most stuff of interest to military, is near earth. there is deep space stuff of interest but when there was a Cold War on Russia would pop up a satellite for various reasons. short orbital life, sometimes on the order of days. and you had to figure out what they wanted to do with it. I kept saying we could call the Russian Embassy and ask....
a lot of US low earth stuff is about 25 deg dec. that's not a geo synch inclination.
there were some highly elliptic stuff that had a long dwell time over higher latitudes. were low altitude over southern hemispheres. much higher at northern.
>>> jkolb@datawest.net 5/22/02 8:04:27 AM >>>
Paul,
> Since your photo was taken close to the ecliptic, note that
> there is a class of _ecliptically_ synchronous spy satellites, one of
> which may have been the cause of your problem. Whether or not these
> are documented in recent literature would depend on the longevity of
> databases of such objects.
What do you mean by "ecliptically synchronous?" Are you referring to
satellites parked at the Earth's Lagrange points, or satellites in
synchronous (24 hour) orbits at about 23.5 degrees inclination? I can
see no advantage to either orbit for a spy satellite - the Lagrange
points are awfully far away, and the inclined 24 hour orbit doesn't keep
the bird over a specific area. If you can tell me more about the
orbital parameters you're talking about, I may be able to find out
what's in that kind of orbit.
> Note that a defunct such satellite may
> have wandered away from the minimum in a specific tessoral harmonic
> of the Earth's gravitational field where it would have been parked
> years ago.
This is a recurring problem with geostationary satellites (equatorial,
synchronous orbits). The big gravity wells near the Indian Ocean and
the Rockies tend to collect the drifters and the dead ones. However, I
doubt that Jim's photo captured any drift - it's simply too short an
exposure and the blob is tapered. My personal guess is that it's a
rotating satellite body.
> Only those who track space junk might know your culprit's
> identity. And please correct me if I am wrong, but I believe NASA's
> group who followed such objects optically were put out of business
> recently by a NASA HQ costcutting measure.
I don't know about NASA, but NORAD continues to track everything the
Space Surveillance Network (SSN) can see. NORAD also provides collision
avoidance assessment for all of NASAs flights, since they're the only
folks who try to track everything. For deep space objects like those in
synchronous orbits, they use variations of the Schmidt camera - first
with film, then more recently with CCDs in the latest generation of
sensors. Only a handful of radars can reach that far, but range data
(not available from optical sensors) helps immensely in correcting the
orbits of these objects. A lot of birds pay the ultimate price for
collecting range data on deep space objects.
Sincerely,
Jon Kolb
Adventures in Astrophotography
http://home.datawest.net/jkolb/
jkolb@datawest.net
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