Celestia Forums

Hello everyone. I have been following this discussion for a few months now. I am very interested in looking at attitude in Celestia, especially since my master's thesis will now encompass attitude constraints. I also have the opportunity to take an OpenGL graphics class this semester! So, I now have...

The Java Astrodynamics Toolkit (JAT) project is working towards making this a possiblity. However, given that the project has limited (sporadic) funding we have been taking much longer than we would like to create this tool. Right now, JAT has a large collection of powerful high-fidelity tools for c...

The XYZQ format will be wonderful. I hope everyone gets the bugs worked out.

As per recent discussion at work, if Celestia can somewhat accurate attitude dynamics, you may start seeing it more as a professional visualization tool!

viva la open source

I think this request is quite a bit more difficult than one might expect. The "standards" for coordinate systems (let alone code standards) are not as "standard" as one might think. They are subject to change every few years. The highly accurate ephemerides from the SPICE library may not be highly a...

Does anyone know of any fairly nice 3ds models of the proposed Crew Exploration Vehicle and/or (new) lunar lander?

Nice!!!

I shall have to look at this in more depth at a later time (ack, Final Exams are upon me already).

That works! Thanks, you're awesome. I usually work from my desktop so I'm used to using a mouse. I shall have to investigate Celestia hotkeys more in depth.

Has anyone ever used Celestia on a Tablet PC (Windows)? I don't know if it is impossible, but the normal ways to "right-click" to orbit bodies in Celestia doesn't work with either the pen or the pad. I haven't tried a USB mouse yet; hopefully that will work. If anyone has any ideas, I'd appreciate i...

Alright, here is an update on progress: I am almost finishing with midterm exams and anticipating making some significant progress over spring "break" in a couple weeks. I've finally amassed enough knowledge of optimal spacecraft trajectories to begin implementing some really useful classes which wi...

OK, how would I go about modifying the trajectory of an already existing mission? For instance, I want to somehow get Voyager 1 to encounter Pluto. Any help would be greatly appreciated. Thanks! J P For right now, unless you have a working knowledge of orbital mechanics, this may be quite difficult...

MKruer wrote:First is to add an option to display LaGrange Point of planets in orbit when the planet is selected. This should be fairly simple to add.

Nice! This would certainly be a cool addition.

Here is an example of the demo that I am including in the latest revision of JAT. It features an orbit for an International Space Station ephemeris on June 1, 2004 propagated for one day. The orbit is subject to the non-spherical gravity of the earth along with the gravity of the moon and the sun. N...

JAT uses planetary information from the JPL DE405 ephemerides. This translates to highly accurate information about the location of the planets in a heliocentric reference frame. Celestia uses VSOP87 expansions. However, if you plot an XYZ path for Earth using JAT, you will find that it lies right o...

You might want to keep your eye on JAT: the Java Astrodynamics Toolkit. It is an open source project which is working to model nearly all aspects of spacecraft trajectories, attitude, and mission design. Sourcecode is available at: http://jat.sourceforge.net I haven't worked out a rendezvous scenari...

Hmmm, if you want to just map inclination and ascending node, you could use my method, but you would need the following points: - Set true anomaly to zero. - Set argument of periapse to zero. - Set semi-major axis and eccentricity to correspond to the following two conditions - You need a velocity c...

There may be a fancier way to do it, but the simple way would be to compute a position and velocity and rotate the frame. http://en.wikipedia.org/wiki/Orbital_state_vectors http://en.wikipedia.org/wiki/Coordinate_rotation The following book is a fairly good reference, though not the best http://www....

Couple points of clarification: Are "heliocentric" XYZ files actually heliocentric or are they barycentric about the Solar System Barycenter? This shouldn't make a difference, but technically the DE405 ephemerides I'm using are Barycentric. What do you mean by "acceleration (20 km/sec/sec)"? Initial...

So, as of a couple days ago, we've released the updated Java Code (revision 57) with the simulation propagator in it. http://jat.sourceforge.net/source.html There are still a few bugs in the XYZ creator, as it gives an Out of Memory error if the timespan of the propagation is too long. In this case,...

Celestia does use quaternions for rotations: they are converted into matrices as the last step. I also had the idea of expanding the XYZ file to hold both position and attitude of the spacecraft. It doesn't look too complex: Celestia code also includes quaternion interpolation functions so a file c...