LEO GPS Sats

[fredinno]

Is it possible (and would it be economical/better) to build a LEO GPS constellation (like LEO the telecommunications constellation OneWeb, but for GPS) and reduce transmission time?

I know the first GPS were put in LEO, but those were experimental, and lacked capability, being tests for GPS2, sent to MEO.

[Steel]

The economy arguament falls down a bit when you look at the (quite large) increase in the number of satellites that would be needed to give reasonable coverage from LEO compared to GSO.

[fredinno]

15 minutes ago, Steel said:

The economy arguament falls down a bit when you look at the (quite large) increase in the number of satellites that would be needed to give reasonable coverage from LEO compared to GSO.

But they'd be smaller, and cost less to launch, wouldn't they?. Compare the Oneweb sats (200 kg) to The most recent Ariane V launch carrying a Eutelsat 65 West A (6.5T)

https://en.wikipedia.org/wiki/OneWeb_satellite_constellation

http://space.skyrocket.de/doc_sdat/eutelsat-65-west-a.htm

[Nibb31]

Would they be cheaper ? GPS sats are pretty expensive birds, with an atomic clock and some unique hardware. It might not be possible to actually make them much smaller, and it might not be economical to make more of them.

[Steel]

1 hour ago, fredinno said:

But they'd be smaller, and cost less to launch, wouldn't they?. Compare the Oneweb sats (200 kg) to The most recent Ariane V launch carrying a Eutelsat 65 West A (6.5T)

https://en.wikipedia.org/wiki/OneWeb_satellite_constellation

http://space.skyrocket.de/doc_sdat/eutelsat-65-west-a.htm

 

1 hour ago, Nibb31 said:

Would they be cheaper ? GPS sats are pretty expensive birds, with an atomic clock and some unique hardware. It might not be possible to actually make them much smaller, and it might not be economical to make more of them.

Yeah you're comparing telecoms and GPS satellites, which are two very different beasts.

Granted they could probably be made a fair amount less massive for LEO but probably nowhere near enough to save you money, considering the OneWeb cluster is 700 satellite to cover the earth (compared to a theoretical minimum of 24 GSO GPS satellites to have coverage) ... And that's before you consider the time cost of launching a cluster that big

On another issue other than cost, the accuracy of the GPS fix would also likely be affected due to the satellite having high relative velocity to both the ground and to other satellites in the cluster

Edited March 22, 2016 by Steel