What is the space station called?

The International Space Station is the largest structure ever built in orbit and is jointly operated by five partners: NASA, Roscosmos, ESA, JAXA, and CSA. It orbits at about 400 kilometers altitude and circles the Earth in roughly 90 minutes; it has been continuously inhabited since 2000. On board, the crew, which is periodically rotated, works on microgravity experiments, from materials research to medicine. Its operation is planned to continue until the end of this decade, after which commercial stations are meant to take over its role.

For some years now, a second inhabited station has been flying: Tiangong, operated by China. It consists of the core module Tianhe and two laboratory modules, is considerably smaller than the ISS, but follows the same principle of living quarters, laboratories, solar panels, and docked transport spacecraft. Crews arrive aboard Shenzhou capsules and stay for months. Still, whoever says "the space station" in English almost always means the ISS: it is visible to the naked eye in the evening sky as a bright, fast-moving point.

Permanently inhabited stations are a young technology, but not a new idea. The Soviet Salyut stations, the American Skylab, and later Mir showed how people can live for months in orbit and where such projects fail: humidity, breakdowns, resupply. The ISS turned that into a permanent laboratory that was never switched off again. That is precisely its most important result: the experience that a stay in space can become routine is a prerequisite for longer flights to the Moon and Mars.