Time dilation affects all processes. The astronauts age slower, though. The effect is a lot smaller in Low Earth Orbit. ISS is a mere ~423km above surface. GPS

Time dilation affects all processes. The astronauts age slower, though. The effect is a lot smaller in Low Earth Orbit. ISS is a mere ~423km above surface. GPS satellites are ~20,200km above surface. Here is the effect for different distances: http://en.wikipedia.org/wiki/File:Daily_satellite_time_dilation.png http://en.wikipedia.org/wiki/File:Daily_satellite_time_dilat...