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Author Topic: Molniya Satellites & Orbits  (Read 3940 times)

ShoeUnited

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Molniya Satellites & Orbits
« on: April 09, 2012, 02:43:17 AM »
A neat thing that most people don't consider is how they get satellites up in Russia. Obviously satellites can't have the usual orbit, or else they'd never get to the northern latitudes.  So, they have to shoot satellites into eccentric orbits.  These orbits and satellites are called Molniya.

So, I created a small simulation showing what these orbits look like from space.  From the ground the satellite shoots up, hangs for a few hours, and then jumps back down.  You need 3 in the proper timed distance (which I'm still having fun trying to adjust) to keep a constant satellite in the sky.  This will show the weird orbits at any rate.  Two are named for easy access to read on wiki in the program.

I have checked this at varying speeds and I do believe I have the orbits stable.  This may be a fun way to check out the night's sky up in the more extreme latitudes.  :)  If not, I'll see what I can do to fix it.


vh

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Re: Molniya Satellites & Orbits
« Reply #1 on: April 11, 2012, 01:09:30 PM »
interesting, how'd you make this?

ShoeUnited

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Re: Molniya Satellites & Orbits
« Reply #2 on: April 11, 2012, 07:22:36 PM »
Well, I always like the weirder orbits in space.  So what I did was do a little bit of google scraping.  I knew I wanted to make a Molniya example since (at least all my life) nobody really talks about them.  So I grabbed some information.  Research told me that the average satellite is about 5 meters and about 5-6 tons. (Imperial for some reason).  Then I went and got the actual numbers for inclination perigee and orbital period.

I used the add tool on a blank map tossed on an Earth.  Locked the Earth in place.  Then went and found something that I remembered should have been about the same size: Monolith.  I <3 2001 and I remembered it was roughly 11 feet by 2 tons.  Which should be close enough to approximate for my example. 

I placed one in orbit around the earth with the timestep paused.  Punched in the numbers (for inclination, instead of putting in -90 I just subtracted 90 from 360).  After that I ran the sim to make sure I got it close to right.  I'd pause the simulation again (with full trails turned on) and tried to eyeball where to place the next satellite.  Wash rinse repeat.  Rename and call it done. lol

I'm sure I'm missing out on some option that'd let me set an object exactly where I'd want it.  But for now it's ok.  The weights and sizes are a bit off, but at that difference in gravitational scale I figured any wobble would be negligible.  But my computer isn't everyone's computer.  And I can clearly see that I didn't get the satellite placement quite right (need a slower timestep or some kinda coordinate cheat code.  XD).  That's why I offered to refine it. 

As a simple example of how a molniya orbit can work though, I think it speaks rather well.  A nice educational tool. :3   But if you want, I can always go and fix stuff up to make it better. :3

Also, thanks for asking. ^_^

vh

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Re: Molniya Satellites & Orbits
« Reply #3 on: April 11, 2012, 07:52:49 PM »
hehe, nice, i've always wanted to simulate the iss orbit or interplanetary satellites but i can never seem to find any data on where they're launched and what velocity they're at. Even when i do, i can never seem to figure out how to translate it into something usable in  universe sandbox. By the way, you can set the exact coordinates in the third? tab of the object, but i don't think satellite positions use cartesian coordinates :P (or do they?)

ShoeUnited

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Re: Molniya Satellites & Orbits
« Reply #4 on: April 11, 2012, 07:56:31 PM »
Derp on my behalf.  You're right.  I also just noticed the ||> next to the pause and play of the time step (moves it at one time step).  >.<

As for the ISS, I think I'll take that as the next challenge. :D  I hope I can get data and do it right.  lol