Discovery’s astronauts tucked a cargo carrier back aboard the space shuttle on Friday, then surveyed their ship to make sure it was safe for the ride home.

With their space station visit drawing to a close, the shuttle astronauts finally got the carrier — and its 2 1/2-tonne load of trash and discarded equipment — into Discovery’s payload bay. The job was supposed to be completed on Thursday, but problems with the latching system for the carrier delayed its removal from the International Space Station.

The trouble dragged on so late Thursday that Mission Control let all 13 astronauts sleep in Friday, the eve of the shuttle’s departure.

Soon after they awoke, Stephanie Wilson and Japan’s Naoko Yamazaki used the space station’s hefty robot arm to transport the 21-foot carrier the final short distance. The arm and carrier had been parked near the payload bay overnight.

“Good job, ladies,” astronaut Dorothy Metcalf-Lindenburger said once the carrier was securely in place.

Then Ms. Metcalf-Lindenburger and her colleagues powered up the shuttle robot arm to inspect Discovery’s wings and nose. The four-hour procedure normally is conducted following undocking. But the failure of the shuttle’s main antenna, way back on launch day on April 5, prompted NASA to move up the operation so that all the mega files of images could be transmitted from the space station.

NASA wants to be certain the shuttle’s heat shield did not suffer any damage from space junk that could jeopardise its return to Earth. Discovery is due to leave the station on Saturday and land on Monday in Florida.

The astronauts had to watch out for all the space station pieces protruding every which way, as they used a 100-foot, laser-tipped boom to scrutinize the shuttle. NASA officials said the job was tricky because of the tight clearances — in some places just 1 1/2 feet. But there were lots of good views from inside to help the crew avoid hitting the station.

This procedure already was in development for one of the three remaining shuttle flights.

The astronauts skipped lunch to wrap up the survey early. They finished three hours ahead of schedule, in fact, and thanked flight controllers for their help with all the preparations. The images were being relayed to Mission Control as quickly as possible, so experts could analyse every single one.

Flight director Richard Jones said a quick look at the data showed nothing amiss.

With their main objectives accomplished, the astronauts got to take it easy for the rest of the day. It was a welcome respite, given that they had been struggling for more than a week with one problem after another.

First the shuttle antenna failed. Then stiff bolts hampered spacewalking work, and then a pressure valve in the space station’s cooling system would not open. Lastly, the latching system acted up.

The astronauts managed to work around each problem, save for the stuck valve.

Currently making its next-to-last flight, Discovery will blast off on NASA’s final shuttle mission in September and take back up the cargo carrier, filled with one last load of supplies and equipment. Then, the carrier will be left permanently attached to the space station, to serve as an extra closet.

The Italian-built chamber is named Leonardo, as in da Vinci.

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