Earth weather satellites

[Ortolan]

Just finished putting together a ssc file with orbital data for 37 weather satellites in geosynch or polar orbit around Earth. Download the file from here:
http://www.skullcave.com/weathersats.ssc
and add it to your celestia extras directory. There's no models or albedo set for them so you can only view them from a distance via their labels at this stage.
It's fascinating to watch the polar satellites go through their orbits with time sped right up. If you notice any errors with the data please let me know. Stay tuned for more satellite ssc files in the coming weeks!
Edit: they're visible as white spheres when you get within a few hundred km of them. I hope to either find or make some 3ds meshes for them at a later date.

[Ortolan]

Here's another 62 satellites in polar orbit:
http://www.skullcave.com/resourcesats.ssc
Space around our little planet is getting pretty busy and I've still got 2400 more satellites to go!

[Sum0]

I assume you're using NORAD's cryptic two-line system for the satellites. I'm trying to simulate a satellite (the one that delivers my satellite tv, actually ) and i've got all the orbital data sorted out - except I can't work out the epoch year and day. Can you tell me what it is so I can convert it to Celestia's Julian date format? Thanks...
This is the first line...
1 25462U 98050A 02198.96484545 .00000000 00000-0 10000-3 0 5008

[Malcolm]

Is this the sort of thing you need :
http://sattrackhouston.com/tleform.htm

if not, do a google on ( tle epoch )

(So I think the year is '02 and day is 198 then the decimal part of the day, but check that I've not got my eyes xxed ! )
I used to do this a lot with a sat-track prog. on the Beeb-B but it was a long time ago now

[Ortolan]

The julian day for that epoch is 2452473.46484545. I use the converter at:
http://heasarc.gsfc.nasa.gov/cgi-bin/To ... ateconv.pl
Hope this helps!

[Ortolan]

D'oh! I just realized I interpreted the revolutions/day as the period. Well that tears it... Move along, move along..

[Sum0]

Thanks! Here's the final code if you want it... I used the Voyager mesh, even though it doesn't look anything like it...

Code: Select all

"Astra-2A" "Sol/Earth"
{
   Mesh "voyager.3ds"
   Class "spacecraft"
   Radius 0.002
   
   EllipticalOrbit {
   Epoch      2452473.46484545
   Period      0.99397328
   SemiMajorAxis   42000
   Eccentricity   0.0005627
   Inclination   0.0484
   AscendingNode   288.5088
   ArgOfPericenter   191.222
   MeanAnomaly   191.3956
   }
   RotationPeriod   24.0
}


[Ortolan]

Putting my time to more efficient use this time, I read some online Perl tutorials (I love the internet!) and wrote a script to convert a NORAD TLE file (you can download these from http://www.celestrak.com) into Celestia's .ssc file format. You can download the Perl script here: http://www.skullcave.com/tle-ssc_orbitconverter.pl
Obviously you will need to have Perl installed to use it (and modify the shebang line if you're a windows user). It reads a file called orbits.txt (containing the NORAD data) from the same directory as the script and appends the data to a file called orbits.ssc (create it as a blank file to start with). It's a bit clumsy I know but I need to learn more about Perl file handling before I can make it easier.