by Conrad Kirksey
Observing artificial Earth satellites is a good way to use your personal computer to “keep track” of developments in space. Mir (the Russian Space Station), HST (the Hubble Space Telescope), Space Shuttle flights, and many other objects are all visible t o the unaided-eye. The upcoming International Space Station (ISS) will also be easily visible. You don’t need a telescope or binoculars.
You need: 1) A computer, 2) a satellite tracking program, 3) recent information on the satellite, 4) good visibility. All calculations are done before the satellite arrives. A satellite tracking program predicts when the satellite will be visible at your location. You should go outside about five (5) minutes ahead of the predicted time to let your eyes become accustomed to the darkness. Artificial Earth satellites are visible when they are in the sunlight and you are in darkness. This usually happens wi thin an hour before sunrise or within an hour after sunset. See the URL at the end of this article for shareware tracking programs.
A tracking program calls a satellite visible if it is in the sunlight, you are in darkness, and the satellite is line-of-sight from your location. There are satellites that meet these criteria; however, they are too far away. Don’t waste your time lookin g for them.
I don’t look for a satellite if the range is over 1,000 km.
A tracking program calls a satellite visible if it is in the sunlight; however, you might be on the dark side. You won’t be able to see a satellite if you are looking at its dark side. Tracking programs don’t know that.
Don’t stop because I use the word “visibility.” Yes, we live in a “dirty fishbowl”, and I’m just a mile from “refinery row.” I haven’t seen the Milky Way in years. You can see the Shuttle, the Mir, HST, and other objects when less than a dozen stars are visible in the sky. Naturally, you cannot see a satellite through the clouds, but you can see them through breaks in the clouds.
My rule: If you cannot see the stars, you will not be able to see the satellite.
Recent information on the satellite is necessary. If the Russians boost Mir into a higher orbit, your tracking program needs to know. If the Shuttle did a burn (fired rockets) yesterday, you need the latest info. Also, orbits tend to decay. The info on a satellite’s orbit is called its Keplerian elements. The Keplerian elements are loaded into your tracking program to keep it up to date. Don’t depend on the sample Keps that come with your program. They will be too old by the time you get the program.
USSPACECOM (formerly NORAD) tracks over 8,000 objects, and Keps for unclassified objects are available to the public.
They are available from the NASA/Goddard Orbital Information Group. http://oigsysop.atsc. allied.com/index.htm
The Satellite Tracking Web Site has all the information needed to track artificial Earth satellites. It also has listings of predicted satellite passes for Houston and other USA cities.
Satellite observing is a hobby that computer users can enjoy.
http://www.hal-pc.org/~sattrack/
Conrad Kirksey is a HAL-PC member.
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