Astronauts begin unloading cargo

Astronauts aboard the International Space Station helped move a giant storage locker full of cargo from the space shuttle Discovery to the station on Monday. Next came the hard part: unpacking.

Crew members aboard the orbiting outpost began unloading 6,900 kilograms ofsupplies Tuesday, including two racks equipped with scientific experiments, a new station crew quarters, a laboratory freezer and a treadmill.

TheDiscovery arrived on Sunday, bringing with it seven astronauts to join the station's six-person crew, which includes Canadian astronaut Bob Thirsk. Discovery also carried with it the Leonardo Multi-Purpose Logistics Module, which contained the supplies.

Monday's installation of Leonardo, using the station's Canadarm 2 to carry it out of the shuttle' cargo bay and to the station's Harmony Node, went smoothly.

Two astronauts who slept in the station's airlock overnightbegan the first spacewalk of their mission at 5:49 p.m. ET on Tuesday.

Nicole Stott, who upon arriving aboard Discovery officially became a member of the station's crew, took her first spacewalk alongside veteran spacewalker Danny Olivas. Together, theyremoved an old ammonia tank.A new tank is to be installed during a Thursday spacewalk.

Communications between the shuttleandMission Control went out for about 30 minutes Tuesday due to a thunderstorm near a satellite relay station in Guam. NASA rearranged some of the spacewalkers' tasks due to the communications outage.

Three spacewalks are planned forDiscovery's nine-day stay attached to the station.

Prior to Tuesday's spacewalk, astronauts moved the $5 million USColbert treadmill into the space station, although themachine is currently inmore than100 pieces and won't be assembled by Stottuntil later this month. The treadmill is named for comedy host Stephen Colbert. The treadmill's official name isthe Combined Operational Load Bearing External Resistance Treadmill.

The astronauts got some good news on Monday when Mission Control informed them that a detailed review of Discovery's heat shield turned up no noticeable launch damage, thus clearing the shuttle for a return to Earth on Sept. 10 without the need for a more focused inspection on Wednesday.