The deep scanner is a ground-reading ship fitting of sensors and antennas, wired through circuits and built in an Assembler. It lets the ship that carries it deep scan the body it is at, which finds sites that prospecting never shows: deep deposits and what the builders left.
Each minute of a scan, every site at the body not yet found has a chance of turning up; the deeper a site lies, the smaller the chance. Scanners on one ship add together.
It is a small fitting. It is fitted and removed at a station with a shipyard in the ship's system.