Space station orbit earth

Space stations orbit Earth at about 400 km altitude, serving as microgravity laboratories for scientific research and technology testing.

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Space stations are artificial structures designed to remain in low Earth orbit (LEO), enabling astronauts to live and work for extended periods. The International Space Station (ISS), the largest ever built, orbits at roughly 400 km altitude, traveling at about 28,000 km/h and completing one lap around the planet every 90 minutes. Since its assembly began in 1998, the ISS has hosted over 250 astronauts from 19 countries, conducting experiments in biology, physics, materials science, and Earth observation.

Other stations have made history. The Soviet Mir (1986-2001) was the first modular station and held the record for the longest continuous human occupation. Today, China operates its own station, Tiangong, whose core module launched in 2021. Tiangong is expected to operate for at least 10 years and has already hosted crews performing experiments and spacewalks.

Maintaining a stable orbit requires periodic reboosts, as residual atmospheric drag slowly lowers altitude. Consequently, stations are regularly resupplied by cargo spacecraft such as Russia's Progress and Northrop Grumman's Cygnus. Life aboard involves challenges like cosmic radiation, isolation, and the need to recycle water and air. Microgravity research has led to advances in pharmaceuticals, metal alloys, and life-support systems, with direct benefits on Earth.

Frequently Asked Questions

What is the approximate altitude of space stations?

Most space stations, including the ISS and Tiangong, operate in low Earth orbit at an altitude between 350 and 450 kilometers.

How many astronauts live on the ISS at once?

The typical ISS crew size is 6 to 7 astronauts, who stay aboard for average missions of 6 months, though shorter and longer stays also occur.

How are space stations resupplied?

They receive supplies via uncrewed cargo spacecraft such as Russia's Progress, Northrop Grumman's Cygnus, and SpaceX's Dragon, which dock automatically to the station.