The 24 ton Zarya (meaning "daybreak") module is based on the long experience the Russian Space Agency has had with the Mir space station. Unlike the US space station Skylab, which was until Mir the largest object in orbit, the module can stay in space for 430 days without re-fuelling. The Russian space company Khrunichev built Zarya under contract to Boeing Aerospace.

After launch Zarya will move into a circular orbit to make it easier for the space shuttle Endeavour to rendezvous with it on 3 December. Astronauts will then dock the US-built module 'Unity' with Zarya. The new 500 ton station is to be built over the next six years by 44 flights, making it the largest and most complex manmade object in space.

The International Space Station is made up by five partners, United States, Russia, Japan, Canada and the European Space Agency. Only ten of ESA's fourteen member states Belgium, Denmark, France, Germany, Italy, the Netherlands, Norway, Spain, Sweden and Switzerland are involved in the project. However, a sixth partner may soon join the list. NASA has approached the UK government to discuss using some UK technologies, such as Matra Marconi's ion thrusters, on the project. "We're in the early stage of negotiations" said a spokesperson from the British National Space Centre.