But the launch of Zvezda sets the scene for the arrival of the construction workers, cosmonauts and astronauts, later in the year. Once it docks with Unity and Zarya, crews will not only be able to take their tea breaks in its kitchen but also sleep in it, look out of the windows, use an exercise bicycle and generally make it a home while they tackle the complex five-year job of putting the station together.
Cynics say the motives are more political than rational.
Originally dreamed up in 1984 in the America of Ronald Reagan, it was set to collapse for lack of funds when, in 1994, Bill Clinton reinvented it as a means to promote cooperation between the west and Russia. But Washington and Nasa underestimated the extent to which the Russian space programme was being starved of funds. At times it looked as if the programme would be scrapped altogether. Now, with the successful launch of Zvezda, the project seems to have reached critical mass, and is set to proceed, although the Russians' own labs may never materialise, making the station slightly smaller. Scientists will use the ISS mainly to examine how familiar chemical and physical processes on earth change when they occur in conditions of weightlessness.