Space station nears completion

 It will be a busy week for astronauts on the International Space Station, with Friday's arrival of a Russian cargo ship and Sunday's scheduled U.S. shuttle launch.

The unmanned Progress M-07M spacecraft, launched from Kazakhstan on Tuesday, completed an automatic docking with the ISS on Friday morning, the Russian space agency said. It delivered 2.5 tonnes of fuel, oxygen, food, water and other supplies, as well as scientific equipment and personal packages for the astronauts.

The station's crew includes Americans Timothy Creamer and Jeff Williams, Russians Maxim Surayev and Oleg Kotov, and Japan's Soichi Noguchi.

Once its cargo is unloaded, the Progress vessel will be filled with garbage and, like its predecessors, will be undocked from the station and burned in Earth's atmosphere. This Progress spacecraft is scheduled to be undocked in May.

There are currently two Progress cargo ships and two Soyuz crew capsules docked at the station, the first time so many Russian vessels have been moored there.

The station will have to make room for one more ship, as the space shuttle Endeavour is slated to launch early Sunday and dock with the station Tuesday.

After Endeavour's 13-day mission, the space station will be 98 per cent complete.

The shuttle is carrying the Italian-built Tranquility module, also called Node 3, which will provide life-support systems and living quarters to the station. It is topped with a seven-window hexagonal dome, called Cupola, which will be used to observe dockings and Canadarm 2 operations.

Astronauts currently use TV cameras and monitors when they're using the robotic arm, and the module's large windows will allow them a direct view. The dome has one large circular window — at 80 centimetres across, the largest ever sent into space — with six trapezoidal windows around it. The windows are made of four panes of fused silica glass and each has a metal shutter to protect it from space junk and micrometeoroids.

The shuttles' contribution to the construction of the space station is scheduled to conclude in September with Discovery's launch carrying the Leonardo multipurpose module. Further station modules, such as the European robotic arm and the Nauka laboratory, will be carried by Russian rockets.

The White House's proposed budget announced this week gave a funding boost to the International Space Station, extending its operation until at least 2020.

Including Sunday's Endeavour launch, only five more shuttle missions are scheduled. After that, the fleet is slated to be retired.