The International Space Station is seen in June 2008. The International Space Station, one of the most ambitious space projects ever and a key launching board for exploration of the solar system, including Mars and beyond, turns 10 years old Thursday.

The International Space Station, one of the most ambitious space projects ever and a key launching board for exploration of the solar system, turns 10 years old Thursday.

On Nov 20, 1998, the first part of the space station was launched by the Russians from Kazakhstan. NASA followed up two weeks later with piece No 2 carried up by a space shuttle.

The space station has grown into a behemoth outpost 355 km up, home to three people at any given time - soon to be six.

Thanks to the newly arrived shuttle Endeavour, the space station now has five sleep stations, two baths, two kitchens and two mini-gyms. All told, there are nine rooms, three of them full-scale labs.

The United States has financed the bulk of the project, estimated to cost some 100 billion dollars. Fifteen other countries have also contributed, including Russia, Japan, Canada, Brazil and eleven nations belonging to the European Space Agency.

The space station has traveled 2.1 billion km, orbited Earth more than 57,300 times, hosted 167 people from 15 countries, and served up more than 19,000 meals.

"The ISS is the largest ever experiment in international technological cooperation," said John Logsdon, a historian at the National Air and Space Museum in US.

"I think it's a necessary stepping stone to long-term human activities in new areas of operations," Logsdon said. The station is "off the planet and it's the first step outward -- not an end in itself, but a step along the way."