If colonists are to have access to space, they will need a craft to transport them.
The craft should be:
- Single Stage to Orbit
- Use propellants that can be obtained from Mars.
- Able to share components with other machines
the craft should have SSTO capability. It has proved very difficult to build an SSTO launcher on Earth, but the lower martian gravity would be of assistance to any launching spacecraft.
Hydrogen and oxygen propellants can be obtained from martian ice. The attitude control thrusters could use gaseous oxygen and methane, kept under pressure.
Early landers will probably be non-reusable or only partially reusable. The decent stages of these landers could be dismantled and reused.