A naturally occurring object flying through space from which gas can be extracted with the fleet's recycling order using the formula recycling speed * [comet diameter]/25000. To find out the amount of gas on the comet and calculate the recycling rate, spy on it beforehand.

A comet can be discovered in an expedition lasting at least 6 hours or stumbled upon accidentally in local coordinates. Comets can be from 13 to 33 km in diameter and fly at speeds from 0.05 to 0.5 km/s, but they can be slowed down by a gravity gun beam. The speed of gas production on slowed comets increases by a factor of 10.

Once a comet is discovered, its local coordinates are stored for 7 days. If necessary, the coordinates of an already discovered comet can be updated by sending an expedition of any duration. Once a comet is in the line of sight of a fleet or station, it ceases to be a hidden object and it becomes possible to send a fleet to it.

The comet permanently loses structure and disappears in about 1000-3000 hours after its appearance. If the comet takes damage, this time is shortened. When a comet is destroyed or disappears, there is no gravity wave and fleets associated with the comet are not destroyed.