According to new data from NASA’s Cassini spacecraft, Saturn’s orange moon Titan has hundreds of times more liquid hydrocarbons than all the known oil and natural gas reserves on Earth.
This reminded me of Isaac Asimov’s The Martian Way — from 1952, reprinted in The Science Fiction Hall of Fame, Volume Two B — in which Martian colonists outwit a demagogue from Earth, who cuts off their water supply. The Martians use water not only to support life on the planet’s surface but also as reaction mass for their spacecraft — not fuel per se, but close.
The Martians, who are much better acclimated to space travel than their Earthling counterparts, make the long trek to Saturn’s rings, where they harness a chunk of the rings, a cubic mile block of ice, to bring back.
A block of solid methane or ethane probably wouldn’t be so convenient to transport.