 April 9, 2013 - 4:34pm | If you haven't seen this already you should check it out: http://distancetomars.com It's a scale model, in your browser of the Earth, Moon, and Mars. Ad Astra Per Ardua! My blog - Expanding Frontier Webmaster - The Star Frontiers Network & this site Founding Editor - The Frontier Explorer Magazine Managing Editor - The Star Frontiersman Magazine |
 April 10, 2013 - 8:03am | I had no idea that the GPS satellite orbit was that far out. Wow. Why the distance? View my profile for a list of articles I have written, am writing, will write. "It's yo' mama!" —Wicket W. Warrick, Star Wars Ep. VI: Return of the Jedi "That guy's wise." —Logray, Star Wars Ep.VI: Return of the Jedi Do You Wanna Date My Avatar? - Felicia Day (The Guild) |
April 10, 2013 - 9:14am | They are in what is called Medium Earth Orbit such that their orbital period is exactly 1/2 a sidereal day. From wikipedia: Orbiting at an altitude of approximately 20,200 km (12,600 mi); orbital
radius of approximately 26,600 km (16,500 mi), each [satellite] makes two
complete orbits each sidereal day, repeating the same ground track each day.[53]
This was very helpful during development because even with only four
satellites, correct alignment means all four are visible from one spot
for a few hours each day. For military operations, the ground track
repeat can be used to ensure good coverage in combat zones. So basically it is so each satellite is always passing over the same part of the earth. Ad Astra Per Ardua! My blog - Expanding Frontier Webmaster - The Star Frontiers Network & this site Founding Editor - The Frontier Explorer Magazine Managing Editor - The Star Frontiersman Magazine |
April 10, 2013 - 11:11am | Ah. I see. Control of orbital velocity. I should have considered that. But then I probably wouldn't have thought about the military importance, so even if I considered velocity, I might not have found the sense in it. View my profile for a list of articles I have written, am writing, will write. "It's yo' mama!" —Wicket W. Warrick, Star Wars Ep. VI: Return of the Jedi "That guy's wise." —Logray, Star Wars Ep.VI: Return of the Jedi Do You Wanna Date My Avatar? - Felicia Day (The Guild) |
