The Syssiphus was a Model 96 "Elephant"-class DropShip operated by the mysterious mercenary unit known as the Star Seeds. While the origin of the Star Seeds was an enigma, the Syssiphus was previously registered with ComStar and apparently lost at the Titan Yards near Terra before appearing with the Star Seeds when the unit registered with the MRBC in June 3068. (The Star Seed's JumpShip, the Tramp-class Vortex was similarly a former ComStar vessel registered at the Titan Yards.) The Star Seeds refused to comment on the origin of the unit or their equipment.
On 13 July 3069 the Star Seeds and the Syssiphus were involved in a conflict on Tomans that also included forces from Clan Jade Falcon and the Green Ghosts. In an operation that involved a ram attack by the Syssiphus and subsequent boarding action, the Star Seeds managed to capture the Silhouette, a Green Ghosts Overlord-class DropShip. The Green Ghosts' JumpShip was unable to fire on the Star Seeds because they kept exactly between the two Green Ghost ships.
The Star Seeds never gave a detailed account of the event later, leading to rumors and speculation on what exactly had transpired. If the rumors are accurate, the Star Seeds had the Syssiphus wait just out of sensor range of the Magellan-class JumpShip the Green Ghosts were operating, waiting for Green Ghosts' forces to attempt to meet up with their JumpShip. When the Overlord-class DropShip being used by the Green Ghosts came within range, the Star Seeds used a combination of courage and remarkable gunnery skills to shoot open the 'Mech bay doors on the Overlord before seizing it with the Syssiphus' magnetic clamps and conducting a boarding action.
The Syssiphus was still in service with the Star Seeds until at least the end of 3071. By February 3072 a vessel referred to as Sisyphus was used by the Star Seeds, which is likely a reference to the same vessel.
- Mercenaries Supplemental Update, p. 109, "Star Seeds"
- Twisting in the Vacuum