Star Trek: Enterprise - Rogue Planet Season 1 Episode 18
Captain Archer is eager to investigate the dark surface of a "rogue" planet — one that has broken out of its orbit. Due to hot gas venting from the planet's interior, small oases have formed, and scans show a surprisingly large number of varied life forms within them. Lieutenant Reed also picks up a power signature — apparently, there is an alien ship on the surface, but it is unresponsive to hail attempts.