Washington  - Space shuttle Endeavour lifted off late Friday from Kennedy Space Centre in Cape Canaveral, Florida for a construction mission to the International Space Station.

The shuttle and its seven-member crew blasted off at 7:55 pm (0055 GMT Saturday) for a planned 15-day flight that is to include four spacewalks to repair joints that allow the station's solar panels to rotate toward the sun and to prepare the ISS for expansion.

Each spacewalk is expected to last more than six hours and will also enable astronauts to install a nitrogen tank, a global positioning system and a camera outside the ISS.

The night launch lit up the Florida sky and NASA said residents of the US East Coast would be able to view the shuttle overhead if cloud cover cooperated.

Just before launch there was some concern about a door on the launch platform that had not been properly secured, but NASA determined that it was safe to go ahead because it posed no danger to the shuttle, launch director Mike Leinbach said in a press conference after take-off.

The Endeavour will deliver 6,538 kilograms of supplies and equipment to upgrade the space station's living space and prepare it for more residents on longer-term assignments, after the retirement in 2010 of the US fleet of aging reusable orbiters.

"It's our turn to take home improvement to a whole new level after 10 years of International Space Station construction," Commander Chris Ferguson said just before launch.

The payload will be delivered in the reusable, Italian-built Leonardo module that will be transferred to the ISS using the shuttle's robotic arm. Astronauts will later fill it with old equipment and scientific samples and bring it back to Earth aboard Endeavour.

The delivery includes an exercise machine, a second toilet, two sleep stations and a water recycling pump to turn urine into drinking water. New kitchen equipment will also be part of the delivery with the addition of two food warmers and a refrigerator.

NASA administrator Mike Griffin said after launch that the system to recycle urine is critical to the planned expansion of ISS crews from three members to six, since it will lessen reliance on deliveries of supplies from Earth.

Astronauts will take water samples for 90 days before drinking from the system to be sure that it works properly and removes all contaminants, he said.

Endeavour astronaut Sandra Magnus will stay behind as a member of the ISS crew, and Greg Chamitoff will return to Earth with the seven- member crew after more than five months in space.

On Saturday, the crew will use a camera attached to a robotic arm to check for any damage to the shuttle sustained during takeoff. Since the launch occurred in the evening, it was difficult to tell whether any insulation had broken off from the shuttle.

Debris that broke off from space shuttle Columbia during launch was blamed for its explosion on re-entry in 2003, killing all astronauts on board. Since then NASA has instituted a rigorous system of checks for damage during each flight. (dpa)