Science Forums 2

[TheBigDog]

I’m curious to see how TBD’s VB.net-based simulator and my MUMPS-based simulator compare.

TBD, can you run yours for the following “standard”, a single geostationary orbit? Here are the parameters (all units kg, m, & s, calculated from this wikipedia article):

* Gravitational constant = 6.6742e-11
* Orbital radius (from center of Earth) = 42164140.10012396182
* Orbital speed = 3074.661175977908351
* Sample position and velocity at 43082 and 86164 s (half and full orbit)

As far as I can tell we had very similar results. But because of how my simulator keeps all of the coordinates relative to a zero point in space it was difficult for me to tell exactly. When I added the sat to the sim it was orbiting the earth, but the earth was moving as it is influenced by the moon, so after a revolution I no longer had a solid frame of reference. I am creating a logging function so that the sim will be like our real life experiment, and the logging will be like the telemetry to do analysis after the fact.

I am also creating a function for adding objects to the simulator in a nicer fashion than I am doing now. I am starting the sim with the earth. As you add objects you indicate what they are orbiting around, their current distance from their parent, and their current speed/direction (along with their mass and diameter). Then when you start the sim it begins with everything in that position.

Because every object is acting upon every other object in the sim (however minutely) I want to indicate somehow what all the paired gravitational forces are. But that might be left read from the output file, rather than from the real time on screen feedback.

The output file from the telemetry is going to be a delimited text file, so you can use any type of program to turn it into useful data for yourself.

Last I will add a graphical part for observing the tests in a fun fashion. All the while I am looking forward to seeing what Janus is cooking up.

Bill