Has a GPS receiver been used on the shuttle while in orbit? At those altitudes (200,000 - 1,000,000 m) does the altitude show correctly? If not, is this due to assumptions in the software, or inherent limitations of GPS? I am interested in the technical details of what would have displayed on a commercial receiver as it proceeded outward piggy- backing on Galileo.
I found some references to adding GPS to the avionics of the Shuttle, but this appeared to be used during landing.
GPS is intended for use on the ground (or at least in the lower atmosphere), but uses triangulation of three or more GPS satelites, which would still give a position in orbit if signals can be recieved. Special software might be required to compensate for this unintended usage, plus I don’t know if the satelites’ transmitters are omnidirectional.
Acording to NASA the ISS has 4 GPS Antennas located on the truss system, I think they use it to help determine the attitude of the station, which is why four are needed and placed along the truss segments
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GPS satellite reception should (and does) work no problem at low-earth orbit altitudes - however, you’ll probably have obstruction issues since the shuttle doesn’t fly “shiny-side” up the whole time in orbit, so the vehicle may block reception of some of the constellation.
Second, an inexpensive commercial GPS receiver probably wouldn’t display much, since they won’t typically spit out a position/velocity solution if they detect that they are above a certain altitude or velocity - this is a security measure so that joe-average can’t put one into his ballistic missile and then have it fly towards a target on its own using GPS for navigation.
Third, in general as long as you have 4 satellite in-view, you should be able to solve for a relatively accurate position (the fourth satellite is required to resolve your local clock error).
To answer your question about what the GPS position/altitude estimate would be as you left earth orbit, you would eventually fly beyond the radiation patterns of enough satellites so that you would lose lock and thus couldn’t solve for position/time. When exactly this happened would depend on how large your spacecraft antenna was and how much processing horsepower you were willing to devote to tracking the GPS signals. Once you leave orbit, it would probably be much easier to just propogate your state to find out where you are. Hope this helps.
To expand on this last point - the GPS satellites transmit most of their signal energy “down” towards the earth, so the received power as you get appreciably “above” the constellation falls off quickly (the satellites orbit at a distance of 26,560 km from the center of the earth).