[Fledermaus]

They better have impulse engines...there are only so many years between the samllest distance between our planets. Propellent won’t work. A nuclear powered engine is the only thing I can see working at this time.

[MinorityRepublican]

Now, SpaceX’s plans for Mars are focusing on a new engine – Raptor and not a Merlin 2 – which will operate on liquified methane and liquid oxygen. The advantage of methane is its cleaner combustion leaving less exhaust deposits within the reusable engines. Furthermore, the Raptor will spearhead development of an engine that will land on Mar and be refueled with Methane produced from Martian natural resources.