Orbital Element to XYZ+time

[UFO64]

I am playing around with a problem with a friend. We are trying to show how much of the moons surface is exposed to earth as in orbits.

The answer is already well known, we are just going though the exercise of doing it through computation. One way we are trying is by sheer bruit force in MATLAB. Yeah, not the most brilliant way to approach the issue, but its a great excuse to learn more about the math involved!

What I am having trouble with, is converting from orbital elements to being able to plot both the orbit of a body as a line, as well as the time specific location of the body itself. I would like to avoid running a simulation of the physics behind the interactions of the orbit, and in the end it would be kind of nice to simple enter a date and plot out the locations of a bunch of planets if I wanted too. I do have a few plans to continue playing with the problem beyond just the earth/moon system.

So far I have spent a week or so toiling around on wikipedia, as well as trolling through every search I could think of for the boards. A lot of people seem to want to go from XYZ+velocity to orbital elements, but no one wants to go back! :beathead:

 

[tblaxland]

You can see how I did it in [ame="http://www.orbithangar.com/searchid.php?ID=3825"]KOST 0.75[/ame]. Even if your C is not up to scratch the code is quite well commented.

 

[UFO64]

Amazing success! I have gotten the basic plotting and location finding down. I need to sit down and do a little playing with getting semi-major axis from a TLE line... Should help with calculating orbit based on time as well.

My only outstanding issue is with my velocity graphs. Seems to estimate that the ISS is moving at around .24 meters per second... Oh well, back to the grind stone. Thanks for the helpful code!