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Propulsion

Five kinds of engine move people and cargo around Saturn, and each is chosen for the one job it does best.

An engine trades thrust against exhaust speed. A hard push that burns fuel fast suits a launch from Titan's surface. A gentle push with a very fast exhaust suits a cargo tug that has months to spare. Nothing in the fleet is the best at both, so nothing in the fleet tries.

Which engine for which job

• Methalox lifts the ascent vehicle off Kraken Shore. Methane comes from the sea and oxygen from the ice, so the town makes its own propellant. See Methalox from Titan and Water, oxygen and electrolysis.
• Nuclear-thermal flies the Gateway shuttle. A reactor heats the propellant and nothing burns. See Nuclear-thermal rockets.
• Nuclear-electric drives the cargo tug between moons. A reactor powers ion thrusters that push very gently for months. See Electric propulsion.
• Fusion carries the Long Passage from the inner system to Saturn. Deuterium and helium-3 fuse, and magnets steer the products out of the nozzle. See Fusion propulsion and helium-3.
• Electric rotors and screws move the rotorcraft and the sea barge on Titan, powered by the reactors on the shore. See Titan's atmosphere and flight.

Every one of them needs somewhere to put its waste heat, and in vacuum that place is a radiator. See Reactors and heat on Titan. For the habitat side of the same problem, Concordia's power and heat page covers how a spinning city sheds its heat.

Where each engine appears

Vehicle numbers are on the fleet page.