Let's imagine that Starship and Super Heavy were currently operational delivering the anticipated performance and reliably performing orbital refueling. As far as I know, Starship is capable of delivering 100 t of cargo to the surface of Mars.
What are the options, if any, to design a mission to have a Starship land on Mars and return to Earth without local propellant production? Assume no actual payload is desired, i.e. one would send only the (autonomous) ship, fuel and oxidizer. For instance, in a touch-and-go style, if possible.
As far as I see, this includes the sub-questions
- How much fuel is required from the surface of Mars to LMO (Low Mars Orbit)?
- How much fuel is required from LMO to escape, and to Earth capture?
Assume (if necessary) to be able to transfer fuel and oxidizer among multiple Starships landed on Mars. Also, assume it's possible to refuel during transfer and in Mars orbit, and include scenarios in which one or more Starships are sacrificed.
What are the options, and if there are any, which one requires the least amount of expended Starships?