HOUSTON, Oct 26: Two astronauts floated outside the International Space Station on Friday on a spacewalk that began a hectic work schedule to ready the orbital outpost for European and Japanese laboratories.

Americans Scott Parazynski and Douglas Wheelock were to work in space for more than six hours on the first of five spacewalks planned while space shuttle Discovery is docked at the station.

“What a gorgeous view, wow,” said space rookie Wheelock as they passed over South America.

Their key tasks were to retrieve a broken antenna from the station, prepare the Italian-built Harmony module for unloading from Discovery’s cargo bay and get a space station solar power unit for repositioning.

After they complete their work on Harmony, the 24-foot cylindrical module will be moved by robot arm to a temporary location on the station.

Later it will be transferred to its permanent position, where it will serve as a berthing port for the European and Japanese science units.

Discovery arrived at the station on Thursday after launching on Tuesday from Kennedy Space Centre in Florida. The shuttle is scheduled to return to Earth on Nov 6.

NASA, the US space agency, has described the mission as one of its most complex and important because of implications for international expansion of the long-delayed space station.Europe’s Columbus module is scheduled for transport to the $100-billion space outpost on Dec 6 aboard the shuttle Atlantis, five years behind schedule.

NASA plans call for Japan’s multi-segment Kibo facility to be delivered on shuttle flights starting early in 2008 and hopes to complete the space station by 2010 when the aging shuttle fleet is to be retired.

Station construction was delayed in large part by the 2003 Columbia disaster in which the seven astronauts on board were killed when the shuttle disintegrated as it returned to Earth.

NASA did not launch another shuttle until 2005 as it investigated the accident and made changes to prevent another.

It was determined that Columbia was brought down by a hole in its wing heat shield, caused by a blow from fuel tank insulation foam that broke loose during launch.—Reuters