They emmit a sort of invisible "net" of energy, that surounds a spherical area extending outward from the probe... the many probes of an area connect, and create a sort of 3 demensional grid, so, in the begining, they're usless, as everything in the area is recorded as natural, but whenever something changes in the area,I.E. a ship comes in, a meteor from another sistem comes in, an asteroid breaks in half, anything of that sort, the probes pick this up, and relay the disturbence to the ship that they are uplinked to.

after the scanners are deployed, they activate a very weak magnetic field about them, and gather in all the space depree of the area, therin disgusing them as just harmless astroid fragments, some fields are stronger then others, therin, making some scanners look larger, and others smaller, allowing for no identical disgues between to scanners.