Optimizing Fly Overs in STK 10

Question

I'm trying to do the math to find the the orbit which will fly over the greatest amount Observatories anywhere in the world. in STK 10, I'm plotting as many observatories as I can and then seeing which ones I hit - a tedious process. I'm not sure STK is able to find this orbit for me once I plot each observatory, as I am very new to the software. if anyone is able to tell me if there is a function within STK that can determine such an orbit for me, I would appreciate it. Otherwise, giving me a rundown on some of the math I'd need to use to determine this orbit would be equally as appreciated.

Answer 1

I can help you here (full disclosure, I'm VP of Engineering at AGI, creators of STK). There's no magical function in STK (or any other similar tool that I'm aware of) that will do this. What they can do is tell you whether you have "coverage", after that it's an optimization problem. Here are a bunch of questions you'll need to be able to answer to help frame out the problem:

1. Fly over during what period of time? 1 day, 1 week, 1 month?
2. What is your definition of fly over? This will get you into using the constraint properties on each of the objects. For example, if you are trying to model when a satellite might be in view of an observatory so it can viewed through the telescope then you might choose the following constraints - a directly sun light constraint on the satellite (so it's lit and visible) and a max ground sun elevation angle constraint of -18 degrees on the facility you are using to model the observatory (this is the definition of astronomical twilight - e.g. it's dark enough out).
3. What is the parameter you are trying to maximize? The number of observatories seen at least once, the total number of "accesses" (even if it's to a limited set of observatories but they are seen often, the total coverage time to any observatory?

A simple approach would be to define a "constellation" object that holds all your facilities (e.g. your observatories). Then build a "chain" object containing the constellation and your satellite. There are various "chain" reports that will then give you the total access times or individual strand times.

You can then vary the satellite orbital parameters via the Connect model to change the orbit, request the chain report and evaluate the impact on the coverage time. You could do this with a Matlab, Perl, Python, (language of your choice) script. Or get fancy and use our Optimizer module which takes out the drudge work of the mechanics of hooking this up.

After you've framed it out a bit try giving our tech support team a call. They would be happy to help out.