How long do satellites operate?

The hard limit is almost always fuel. In geostationary orbit, position must be corrected continuously, and in low orbits the residual atmosphere drags on the satellite and forces its orbit to be raised. In parallel, everything else ages too: solar cells lose power under radiation, batteries can only withstand a limited number of charge-discharge cycles, reaction wheels wear out at their bearings, and energetic particles damage the electronics. Redundant components extend service life, but they don't replace an empty tank.

Well-managed operators reserve fuel at the end to actively deorbit the satellite. In geostationary orbit it gets pushed into a graveyard orbit above the traffic; from low orbits it is deliberately steered into the atmosphere, where it burns up. Since 2022, U.S. regulations have required new satellites in low orbit to disappear within five years of the end of their service; in Europe, the space agency is pushing for an equally strict approach. Anyone who waits too long risks losing control, and a hull with no maneuverability becomes a collision risk for everyone else.

Some specific spacecraft hold out far longer. Voyager 1 launched on September 5, 1977, and is still transmitting, because it uses radioisotope generators instead of solar cells and doesn't need to maintain any orbit in interstellar space; for years now, individual instruments out there have simply been switched off one by one to save power. The Hubble Space Telescope also remained useful for an unusually long time because crews repaired and upgraded it several times in orbit.