From Space Exploration
Lifesupport window from Space Exploration

Lifesupport is required to survive outer space and other hazardous environments. Space includes orbits, asteroid belts, and asteroid fields. While lifesupport is required, the Lifesupport canisters in your inventory automatically deplete and are replaced by Empty lifesupport canisters. Once those run out, you should seek the safety of a Space capsule or Spaceship, or return to a planet! Certain equipment, if installed in your suit, can extend the working life of your canisters; while other recipes let you clean and refill empty canisters. For the base Thruster Suit, at 100% efficiency, the duration of a single Lifesupport canister is 1:40s.