The Alien Probes are weapons used by the Centauri police that went to Earth to capture Blackfire.
In "Sisters", four probes were sent by the Centauri Police to Earth to catch their criminal. One of the probes managed to find Starfire and attempted to capture her, however it was destroyed by Robin. The Centauri Police then tracked down the site where the probe was destroyed and concluded that their criminal (which should have been Blackfire) is on that location.
During a disco party, Starfire once again encountered the probes and could not free herself this time. In retaliation, the Titans could not make a scratch on the probes, however Blackfire was able to destroy the probes easily with her blackbolts.