Can anyone answer this? GPS satellites are preprogrammed before launch due to relativistic effects mainly time dilation and gravity. Yet, once in orbit, the satellite should view the earth frame as "moving" and thus apply time dilation to the earth frame meaning the earth clocks should beat slower. This does not happen. Questions, why does time dilation only apply one way with GPS satellites. The effects are emphasized for several different orbit radii of particular interest. For a low earth orbiter such as the Space Shuttle, the velocity is so great that slowing due to time dilation is the dominant effect, while for a GPS satellite clock, the gravitational blueshift is greater. The effects cancel at . The Global Navigation Satellite System GALILEO, which is currently being designed under the auspices of the European Space Agency, will have orbital radii of approximately 30,000 km. http://relativity.livingreviews.org/Articles/lrr-2003-1/ [Broken] See chapter 5.