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You can sign up on the "Spot The Station" site to receive text messages when it is going to fly over your area.
I liked the text messages, since you don't have to check the site. When you get the text, you can set an alarm on your phone to look for it at the proper time. I was surprised to find out how frequently it flies over the Northeast U.S.
So frequently that after seeing it pass over about 10 times in a couple of months I tried to opt out of the text messages. Got an error every time I tried. No worries though. You automatically get dropped from the text messages after a period of time if you don't renew your preferences.
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Thanks, Chas. Didn't realize you could sign up for alerts, but if you enter your location and search, the option is there. It makes a lot of sense doing it that way.
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Tom et al: I've been googling around and haven't found much yet. I'm curious about the ISS orbit. Does mission control steer that thing around live all the time, or is the ISS in some sort of a "precessional" orbit?
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beejee,
You have to remember the ISS is simply orbiting, but its orbit is being projected onto a "flat" map of the Earth. If you could wrap that flat map into a sphere, you would see the orbit is pretty much fixed. Add to that the Earth rotates at a different rate to the orbital period of the ISS (roughly 90 minutes), the track of the ISS will keep changing when it's projected onto a 2-d map.
The ISS does have access to thrusters that are occasionally used to adjust its orbit. Even though it's in space, there is still a very minute drag caused by molecules at the edge of our atmosphere, so its orbit decays over time. Every so often it needs a nudge to move it a little higher. As to major changes in its orbit, no, it doesn't have the ability to do that.
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Incidentally, for anyone interested, PBS has just started three hours of Nova about Einstein and relativity (started at 9pm). It's the 100-year anniversary of his theory of relativity.
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Tom: I think I got it. In layman's terms... The ISS has a fixed orbit around the earth, it always traces the same circular path. At the same time, the earth is rotating beneath, so the net effect is that the ISS flies directly over most places on the globe in due time.
Fair statements?
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Yes, beejee, you're get it! What generally confuses people though, is projecting the orbit onto a 2-d map when everything is actually happening in 3-d around a sphere, but you're well on the way to getting it now!
I'll try and find a website that might show this in movie format, it'll all become clear when you see it visually.
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This place has both a 2-d and 3-d projection of the ISS's orbit. It's the first I found so may not be the best, but hope it helps visualize what's going on.
http://www.satflare.com/track.asp?q=25544#TOP
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In non-layman's terms... It's the angular difference in the rotational axes of the earth and the ISS that creates the "precessional" ground track . It makes perfect sense to me now that you explained it Tom. Thanks!!
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You made my day. Thank you!
