Probe droids use electromagnetic, seismic, acoustic, olfactory and optical sensors. They report their findings using an omnisignal unicode.
Use 2 Force to search any Lost Pile and place X non-unique cards there out of play, where X = number of Probe Droids on table. OR If your only character on a planet is a Probe Droid, your cards are deploy -1 to related sites for remainder of turn.