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ISS orbital data
Posted: 14.09.2006, 08:35
by bh
Hello folks...I was fed up of watching nasa tv and having celestia display the iss in the wrong place!
These are just about spot on...
EllipticalOrbit {
Period
0.064176392
SemiMajorAxis 6767
Eccentricity 0.0011498
Inclination 51.6335
AscendingNode 090.8292
ArgOfPericenter 355.6166
MeanAnomaly 14.6783
Epoch
2452028.18381755
}
Obliquity 51.5684 #
RotationOffset 90
#orientation corrections by Matt McIrvin
EquatorAscendingNode 343.1518 #
Albedo 0.10
}
At last!
Posted: 14.09.2006, 10:41
by Adirondack
Posted: 14.09.2006, 11:26
by bh
I'm afraid both sscs put the iss in the wrong place.
I suspect that my code above will start to drift somewhat too. Will probably need updating daily or after a few hours. Edit: After about four hours I'm about three hundred miles north of it's correct position...knickers!
Edit 2: Ah!...I'm now drifting behing the station's actual position by 2/300 miles...so I'm guessing the orbital data is correct and I'm lacking speed. I reckon I need to adjust the Period? Going to be a bit tricky.
Posted: 14.09.2006, 11:50
by selden
Unfortunately, Celestia's EllipticalOrbit can't give the right results for the orbit of the ISS for very long. It can't take into account all the irregular forces that are at work -- like atmospheric drag and the irregular shape of the Earth, for example. Either you have to update the parameters frequently, (at least daily) or you have to use some other way to define the orbit.
For example, the most recent version of Celestia built from CVS includes support for Spice. I haven't found any Spice Kernels for the ISS, but maybe they're available somewhere...
Posted: 14.09.2006, 11:54
by Adirondack
bh wrote:I'm afraid both sscs put the iss in the wrong place.
I suspect that my code above will start to drift somewhat too. Will probably need updating daily or after a few hours. Edit: After about four hours I'm about three hundred miles north of it's correct position...knickers!
Of course both ssc's put the ISS in the wrong place, because the epochs of the ssc's are out of date now too!
Didn't you read the info.txt?
Code: Select all
Please note, that Celestia models the shape of the Earth using a spheroid. The actual shape of our planet is much more complicated. As a result, a view from the Earth's surface in Celestia is not accurate enough to show the correct path across the sky of satellites in low Earth orbits (like the ISS). In other words, you can't use Celestia to find out where to look in the sky to see the ISS!Adirondack
Posted: 14.09.2006, 12:11
by bh
Thanks matey...yep I did read that! Looking for new data.
Posted: 14.09.2006, 19:07
by LordFerret
Posted: 14.09.2006, 21:43
by guest jo
But there was the spreadsheet for converting TLE??s directly into ssc-language.
Isn??t it working anymore ?
(I made a openoffice-version cause the original didn??t work in german-Oo.)
Posted: 14.09.2006, 22:36
by selden
It's still working so far as I know
I'm guessing people have forgotten about it or (if new to Celestia) don't know of all the utilities Grant has provided.
http://www.lepp.cornell.edu/~seb/celest ... heets.html