An activity of an artificial satellite that uplinks and processes data from another satellite or surface vehicle, such as a lander or rover. The Mars Global Surveyor is designed for radio relay using its Mars relay antenna, and NASA's proposed Mars Network of satellites will increase communications for future probes. These spacecraft are able to have extended missions, since radio relay requires little propellant and attitude control. A satellite on its own scientific mission, however, must reduce or interrupt some of its own data gathering activities to serve as a relay.
Subjects: Astronomy and Astrophysics.