This is a beautiful night to fly

Mike Leinbach, launch director

The shuttle's five astronauts will deliver and install a pair of giant solar wings on the International Space Station (ISS).

As the shuttle blasted off, the ISS was 370 kilometres (230 miles) above the Indian Ocean - its three residents supposedly asleep. Endeavour is due to catch up with the station on Saturday.

Costly cargo

The $600m solar panels in Endeavour's cargo bay are dotted with some 64,000 photoelectric cells.

High spirits: Pilot Michael Bloomfield boards Endeavour

The crew will install the wings in a folded position, and then allow them to automatically unravel to their full length of 73 metres (240 feet).

The panels will provide the ISS with enough electricity to power all three modules currently in space and the American laboratory component, Destiny, which is due to be added in January.

'Historic'

Veteran astronaut Brent Jett is commanding the Endeavour mission, with Michael Bloomfield serving as pilot. They are accompanied by Joe Tanner, Carlos Noriega and Canadian Space Agency astronaut Marc Garneau.

It will be Tanner and Noriega who will go outside the orbiter to attach the giant solar panels to the station.

"This mission will assemble the heaviest, largest and most complex piece of the International Space Station to date," said Ron Dittemore, the space shuttle programme manager.

The ISS will be a unique research laboratory

"Every shuttle flight for the next year carries its own set of firsts. But this mission, unfolding solar arrays of historic proportions, will make the challenge and grandeur of this entire venture more apparent than will any other single flight."

The new panels will also make the ISS clearly visible from Earth, which space scientists hope will increase interest and support for space exploration.

"People will be able to look up and see the brightest new star in the sky," said Nasa space development administrator Michael Hawes.

He said that only a handful of objects, such as Sirius and the Moon, would appear brighter from Earth.

Christmas in space

The new power from the solar wings will also allow the three current residents of the ISS - Bill Shepherd, Yuri Gidzenko and Sergei Krikalev - to open one of its modules that has been sealed since their arrival almost one month ago.

The orbiter crew and the station residents will spend little time together during this mission. The hatches between the shuttle and ISS will not be opened until all three spacewalks are complete.

For a variety of reasons, air pressure is kept lower aboard the shuttle than on the station when astronauts are moving back and forth through airlocks.

The two crews are scheduled to spend only about a day together, and most of that will be spent stowing space station rubbish on the shuttle for the return flight to Earth.

Endeavour's crew will also play Santa Claus to the three men now living on the ISS. Shepherd, Gidzenko and Krikalev will be in orbit over Christmas.

Technical glitch

Endeavour's take off was nearly delayed.

Technicians had to remove a loose bracket spotted hanging from the launch pad. The emergency began just minutes before a deadline to begin pumping hundreds of thousands of litres of fuel into the spacecraft.

Nasa officials feared the bracket could break off and strike Endeavour's wing during the lift-off.

In October, a 10-centimetre (four-inch) pin was left on Discovery's external fuel tank and delayed the flight by one day.