Orbital probe

From Memory Alpha, the free Star Trek reference.

An orbital probe is a probe utilized by the Romulans to scan a planet from orbit.

In 2366, a cloaked orbital probe was in orbit of Nelvana III with an eight hundred kilometer apogee, scanning the planet for archaeological research. The probe was emitting ionization disturbances, leading the Federation to believe that the Romulans had established a base on the planet. (TNG: "The Defector")