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--- blog:articles:general:orbital_shenanigans [2019/03/14 15:33] – Phil Ide
+++ blog:articles:general:orbital_shenanigans [2019/08/03 11:19] – Phil Ide
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 Sometimes when you do some research – actually, quite often – you find out some really interesting stuff and end up changing your mind. In my story, I had some people on the ground on Mars, and wanted a spacecraft in a geostationary orbit above them to give them communications between them at all times. Just for info, when talking about geostationary orbits, the accepted term for Mars is aerostationary. I’ll use geostationary and geosynchronous because it’s my blog and although the aero prefix is accepted, it isn’t mandatory.
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-Since I’ve written a program that can calculate orbits around Mars (see the download section), figuring out the orbital parameters is easy enough for me, but I decided to check my results against published scientific papers. I like to be thorough in my research. This resulted in a delightful piece of serendipity, which I’ll talk about in a moment, and turned up some fascinating facts about these peculiar types of orbit that I’d never heard of.
+Since I’ve written a [[blog:articles:software:orbital_calculator|program to calculate orbits]] (including around Mars), figuring out the orbital parameters is easy enough for me, but I decided to check my results against published scientific papers. I like to be thorough in my research. This resulted in a delightful piece of serendipity, which I’ll talk about in a moment, and turned up some fascinating facts about these peculiar types of orbit that I’d never heard of.
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 To begin, I should explain the difference between geostationary and geosynchronous. I’ll use Earth as an example to make the explanations easier. The International Space Station lies at an elevation of 250 miles. It completes an orbit once every 92 minutes. The further away from the planet the orbit, the less the gravitational influence, and so the orbital speed is reduced. So the satellite is moving slower, but the circumference of the orbit is getting bigger, hence the orbital period – the time to complete a single orbit – gets longer. Keep moving out, and eventually you reach a point where the period of the orbit equals one day. This equality is a geosynchronous orbit, because the period of the orbit and the rotation of the planet are synchronised.