Composed almost entirely of ice, Tethys is one of Saturn’s larger moons and the site of Ithaca Chasma, a 2,000-kilometer long valley covering three-quarters of Tethys’s circumference. Fifteen years ago, prospectors from an ethnically Indo-British autonomist collective called the Rioters touched down on Godwin Head, a projection in the chasm wall so named because it resembles a headland projecting out into the sea. Instruments on their ship, the Caleb Williams, had detected what looked like mineral deposits in the ice, rare on Tethys. What they found instead were relics thrust to the surface by a geological event eons earlier, the remains of primordial life that became extinct millions of years ago when Tethys cooled and its sub-surface ocean froze over.

Godwinhead is now a dense, efficient settlement of 200,000 built into the five kilometer high canyon walls. The central point of the town is the Caleb Williams, which has been towed back into a sheltering cavern in the wall and converted into a communal workshop and town hall. The face of the valley wall is honeycombed with excavated ice caves hosting habitat modules, connected by conduits to a communal utility grid. The trusswork and cabling for the utility system is also the public transit system, easily traversed in the minute Tethyan gravity. The unof cial mascot of Godwinhead is the Tethyan Flatworm, a two millimeter-long translucent worm that represented the pinnacle of Tethyan evolution. A large number of the inhabitants are involved in biosciences, xenopaleontology, and prospecting for frozen lifeforms.

Tethys shares its orbit with its Trojan moons Telesto and Calypso, both of which are small and sparsely populated.