The Survey Satellite is a modified Communications Satellite designed to relay information between planets. It is not able to move once released. It can be docked, but only one docking port is present.
The Survey Satellite is used in Mission 18 along with the Atmospheric Probe.
In conjunction with the probe, it is supposed to be a relay satellite, able to relay information from the descending atmospheric probe to HOM while in orbit around GRN.
It still does its purpose when you re-enter an Atmospheric Probe and point the Survey Satellite down to the planet, but the "data" it receives has no use to the game in Sandbox.