People have lived continuously in orbit since 2000. The International Space Station is the largest and longest-running example, a modular structure assembled over years and crewed by rotating teams from multiple countries.

Life aboard revolves around maintenance. Astronauts spend hours each day repairing equipment, running experiments, and exercising to counter bone and muscle loss. Supplies arrive on cargo vehicles, and crews return on capsules docked to the station.

Core modules and systems

• Pressurized modules for living and working
• Solar arrays for power
• Thermal control radiators
• Docking ports for visiting vehicles

Future stations may be commercial rather than government-run. Several companies are designing inflatable or modular habitats to replace or supplement the ISS after its retirement.