NASA astronauts have attached a Russian docking and research module onto the International Space Station, bringing the $100 billion complex to near completion.
The compartment, known as Rassvet - Russian for "dawn" - was delivered aboard the shuttle Atlantis, which is making the third-to-last flight of the shuttle programme.
Russia plans to launch its prime research laboratory in 2012, which will complete the $100 billion orbital outpost, a project of 16 nations that has been under construction 220 miles above Earth since 1998.
Nasa has two shuttle missions remaining. Discovery is due to fly in September with a final load of spare parts and a storage pod that will be left at the station.
Endeavour, on Nasa's 134th shuttle flight, will mark the programme's finale with the delivery of the $2 billion Alpha Magnetic Spectrometer particle detector. The physics experiment will be mounted outside the station.
With Rassvet, the station now has 13 rooms, including two core Russian modules (Zarya and Zvezda) and three major laboratories.