The International Space Station after its latest renovations. NASA expects a long, difficult journey to complete the orbiting research station.

Related articles

• Spacewalkers instal power on space station
• Space walk a success
• Shuttle launch imperiled by coming storm
• Atlantis astronauts step out on space walk
• Shuttles ready to complete International Space Station

HOUSTON: The installation of new solar panels on the International Space Station (ISS) by the shuttle Atlantis crew marks just one stage in the difficult task of completing the orbital laboratory by 2010.

The space station and the laboratories it will eventually hold are a crucial part of the U.S. space agency's goal of returning Americans to the Moon, and also to set the stage for later expeditions to Mars.

The Atlantis mission was complex but succeeded beyond expectations, said Mike Suffredini, NASA's space station program manager, during a press conference.

The six Atlantis astronauts undocked from the space station Sunday, days before the arrival of a Russian Soyuz rocket. The shuttle is scheduled to land in Cape Canaveral, Florida on Wednesday. Suffredini however warned that future building missions will be even more difficult and include tasks never performed in space.

The ISS construction was put on hold when the space shuttle Columbia disintegrated as it tried to re-enter the Earth's atmosphere on February 1, 2003.

The station remained half-finished until last week, when the Atlantis astronauts used the ISS's Canadian-made robotic arm to attach a 16-tonne truss segment with two giant solar arrays. It took two teams of astronauts three spacewalks lasting more than 20 hours to install the module and on the way home, a chemical leak caused brief consternation within the shuttle.

The solar arrays, unfurled Thursday, measure 73 metres, and will ultimately provide a quarter of the outpost's power once it is completed. They will be activated during a space shuttle Discovery mission planned for December, doubling the space station's current power capacity.

Discovery's December mission will be particularly complicated, said Suffredini. The shuttle crew and the Russian, American and German working on the ISS will be tasked with activating permanent air-conditioning and power supply systems.

To achieve that, the astronauts will have to overhaul the whole electrical grid, including the wiring, and do that without interrupting any of the vital ISS systems.

Once this delicate operation is finished, the U.S. shuttles will be able to deliver and install the Columbus and Kibo laboratories, manufactured by European and Japanese firms respectively. These and other components will be installed during the next four shuttle flights, increasing the station's weight to nearly 40 tonnes.

When it is finished in 2010, the station will be bigger than a five-room house and weigh approximately 450 tonnes. It will be equipped with four double solar panels capable of generating 110 kilowatts of electricity, enough to supply roughly 55 middle-class homes.

About 46 kilowatts of that will be used for scientific research, the scope of which will more than triple compared to what is currently available.

Of the 115 flights completed by U.S. space shuttles since April 1981, 18 have been dedicated to the ISS. NASA plans 15 more to finish the project by 2010. At that time, the three orbiters remaining in the U.S. shuttle fleet are scheduled to be decommissioned.