When scanned, it produces data (often rare and very rare).
Finding Satellites Edit
To Find a satellite, you can orbit a planet between 6Mm - 10Mm, at 10% - 20% throttle and drop in to Encoded Emissions signal sources. They're usually at inhabited Earth-like planets. Check that the dark side of the planet has city lights.
Target a planet, get a decent orbit distance where your FSD max is 200km/s or more. For example at Earth it's a 7.5mm orbit. Then you can maintain the distance and fly around until a Unidentified Signal Source appears. With an Encoded Signal Source it's often a satellite. These can give data such as Specialized Legacy Firmware.