A Brief History of the International Space Station

The International Space Station is the largest structure humans have ever put in space. It stretches roughly the size of a football field, weighs about 420,000 kilograms, and has been continuously occupied since November 2, 2000. Building it took more than a decade of cooperation between five space agencies - NASA, Roscosmos, ESA, JAXA, and CSA.

The early days

The idea of a permanently inhabited space station goes back to the 1980s, when NASA proposed Space Station Freedom. After the Cold War ended, the project merged with Russia's Mir-2 plans, and the International Space Station program was born in 1993. The partnership brought together the United States, Russia, Europe, Japan, and Canada.

On November 20, 1998, Russia launched the Zarya module - the first component of the ISS - aboard a Proton rocket from the Baikonur Cosmodrome in Kazakhstan. Two weeks later, Space Shuttle Endeavour delivered the Unity node, and astronauts connected the two modules during a series of spacewalks. The station had its first building blocks.

Growing piece by piece

Over the next 13 years, more than 40 assembly flights brought additional modules, solar arrays, radiators, and truss segments to orbit. Each piece had to be designed to fit together in microgravity, connected by astronauts working in spacesuits outside the station.

Some key milestones along the way:

• 2000 - The first permanent crew (Expedition 1) arrived on November 2. The station has been continuously inhabited ever since.
• 2001 - The Destiny laboratory was installed, giving NASA its primary research facility.
• 2007-2008 - ESA's Columbus and JAXA's Kibo labs were added, making the station truly international.
• 2011 - Assembly was considered complete after the final Space Shuttle mission (STS-135).

Life today

The ISS typically hosts six to seven crew members at a time. They spend about six months on board, conducting hundreds of experiments in biology, physics, medicine, and technology. The station orbits Earth every 90 minutes at roughly 400 kilometers altitude, meaning the crew sees 16 sunrises and sunsets every day.

The station is expected to remain operational until at least 2030, after which NASA plans a controlled deorbit. Until then, it continues to serve as a unique laboratory, a platform for testing deep-space technologies, and a symbol of what countries can accomplish when they work together.