Celestia Forums

I have a couple of questions...

What is the date format used in the .ssc files for spacecraft? How to convert from ddmmyy to that format? I would like to implement beginning and ending dates for some of the craft zipping around in Earthspace.

How does Celestia read the .ssc if there are more than one set of dates? Will it use all of them, or just the first set? (Shuttle missions).

BTW, a huge thank you to the developers - for building Celestia, distributing it for free, and even porting it to OS X. Great work!


-rthorvald

rthorvald wrote:What is the date format used in the .ssc files for spacecraft?

Julian date - a continuous count of days and fractions since noon Universal Time on January 1, 4713 BCE (on the Julian calendar). Almost 2.5 million days have transpired since this date.

How to convert from ddmmyy to that format?

A good converter can be found at... http://aa.usno.navy.mil/data/docs/JulianDate.html

How does Celestia read the .ssc if there are more than one set of dates? Will it use all of them, or just the first set? (Shuttle missions).

Each craft (object) can only have one beginning & one end date. You can have as many objects as you want in an ssc file though, with different start/end dates for each object. Celestia only renders the particular object between the start/end dates!

I wonder if it might be possible in the future to have some algebraic formula + date -so it might be possible to have a simple kind of animation going on in Celestia.e.g.The shuttle on launch pad,then in orbit,then docking with the ISS then back in orbit,then back on the launchpad to start the cycle again-just a suggestion I dont know how easy this would be to program.All the best Jestr

jestr wrote:-so it might be possible to have a simple kind of animation going on in Celestia.e.g.The shuttle on launch pad,then in orbit,then docking with the ISS then back in orbit,then back on the launchpad to start the cycle again

I am fairly new to Celestia, but it seems to me this could be done by describing the launch as a short, fast orbit, accompanied by a script that follows the shuttle. It would need two different shuttle configurations (with/without fuel tanks), the second one taking over where the first one disappears into the past.

Now, with a texture for the ground in Florida too, that would be a great add-on. I have to learn how to do this...

-rthorvald