💧 Living off the land

Rockets are expensive, so colonies must use what they find — engineers call it ISRU, in-situ resource utilisation.

• Ice lies in permanently shadowed craters at the Moon's poles and under Mars's surface.
• Water can be split into hydrogen and oxygen: rocket fuel and air.
• NASA's MOXIE made oxygen from the Martian air between 2021 and 2023.
• Rovers have explored Mars since 1997.