In the near future we may be witness to an advancement in the use of materials that harken back to the earlier days of the US space program. And a rocket constructed of one of the early materials, stainless steel, that will be powered by methane, aka “swamp gas”.
SpaceX, after planning to use composite fuel tanks and aluminum alloy rocket bodies suddenly dropped that after considerable expenditure in the manufacturing processes needed and designed and started production of a prototype “Star Hopper” sub-orbital vehicle, primarily from stainless steel. They are doing this an open part of their Boca Chica, Texas facility. The narrator makes a great comment, calling the finned, short and stout shape of this vehicle as looking like “an H.G. Wells fever dream of the future”. It looks nearly Art Deco to me.
A controversial part of this design is the planned use of cooling pores in the outer skin of one side of the ship, to serve as a “heat shield” by expelling methane to dissipate the heat of re-entry. As the full up Starship model is intended to go to Mars, do an atmosphere entry there and then come back to Earth and do a re-entry here, an ablative type of heat shield will not serve.
Methane is the fuel of choice for both Blue Origin's new BE-4 and SpaceX's Raptor rocket engines. The complexity of why this is a good selection takes a good bit of an excellent video I have watched three times to try to absorb all the basic facts. Neither engine has flown yet but the commitment is there to make each a reality, as they are both far along in development and testing for flight.
The BE-4 will power Blue Origin's New Glenn heavy launch system and United Launch Alliance’s Vulcan rocket. The Raptor will power the SpaceX Star Hopper sub-orbital development vehicle and the ambitious Starship heavy launch system they intend to use for orbital cargo, missions to the Moon and also Mars.
Of note, methane can be produced on Mars, if needed, to fuel a return journey to Earth. No one said this was going to be cheap or easy! Hydrogen can be produced as well. Both will require water ice to be mined.
I am going to link in two YouTube videos that address both subjects, one relatively short and one nearly 50 minutes long. They both do a superb job of explaining each subject for we non-engineering types. The longer video, from Everyday Astronaut, has time stamps to go to individual segments. Disclosure, Everyday is a SpaceX fan.