In the 20 years since it was launched in November 1998, the International Space Station has delivered on its promise for scientific exploration in the unique environment of space.
Built over 13 years at a cost of over $100 billion, the ISS orbits Earth every 90 minutes, travelling at a speed of 28 000km/hour.
Fifteen countries are participants in the programme, and the ISS typically has six permanent crew, who stay for around six months at a time.