[jccooper]

Methane, while less dense (thus requiring bigger tanks) has a higher specific energy than kerosene, and thus has a higher ISP (rocket efficiency). Methane is also less sooty and should have better cooling as its a "mild cryogenic" like liquid oxygen.

Basically, it's between LH2 (hydrogen: high ISP, very low density, very very cold) and RP-1 (kerosene: lower ISP, high density, room temp) and may be a good compromise.

And its derivable on Mars. Downside is there's very little flight heritage for a methane engine, so most of this is theoretical.

EDIT: Paper: http://thehuwaldtfamily.org/jtrl/research/Propulsion/Rocket%...