As crewed missions arrive on the surface, the first priority would be scouting and processing local supplies. Starships are designed to run on liquid methane-oxygen fuel, Wooster said, in part because of the low cost of those ingredients on Earth but also because scientists believe they can be produced on Mars. Among the first tasks for Starship missions would be mapping the availability and accessibility of the raw materials for that fuel, so humans would have a way to get back home to Earth.