Astronauts sealed into shuttle, ready for launch

Canadian astronaut Steve MacLean and his five crewmates have boarded the space shuttle Atlantis and the hatch has been closed in preparation for a much anticipated NASA launch in Florida.

Earlier, they donned their orange space suits, then took a silver "astrovan" to the launch pad where Atlantis was docked, as crews prepared the spacecraft for the launch scheduled for 11:40 a.m.

NASA crews fuelled the shuttle early Fridaybut they were forced to attend to a fuel sensor problem as preparations got underway.

The U.S. space agencyis proceeding withthe mission despite the problem with one of the power cells, although it could cancel the launch at the last minute because of safety concerns.

MacLean and his crewmates entered the shuttle one by one, each taking their designated seats, with the commander of the mission going in first. It has been 14 years since MacLean was last in space. He reportedly has a window view.

Col. Chris Hadfield, a Canadian astronaut and NASA chief of space station operations, said Friday that the six astronauts had to ride an elevator about 60 metres in the air before boarding. "The crew is being taken in one at a time. The commander gets in first. His seat is furthest from the exit," he said.

Hadfield,who has been in space twice,recalled the most exciting moment before the actual launch. "You know, putting on the suit doesn't mean much. The actual suiting up is a very familiar process. Getting into the big silver astrovan, that's a new thing," he said.

After suiting up, the astronauts walk out of a building to board the van. "There's all those people cheering," Hadfield said, "and you see the space ship up there and suddenly, it's not a space ship it's your space ship."

Hadfield said the astronauts reflect on their impending journey while they're in the van. "We say the astronaut's prayer, which is 'Please don't let me screw up,'" he said.

Thenit's time to board. Hadfield said the astronauts on this mission know that NASA could decide to scrub the launch at the last minute because of the fuel sensor problem but he thinks the mission will be good to gobecause the other three sensors are operating.There are four in all that monitor levels of fuel on the shuttle.

"This is such a tiny little risk and a well understood problem that I think we are good to launch today."

This fuel sensor problem is different from an earlier problem that emerged this week with an electricity generating fuel cell.

Crews pumped more than 19,000 litres of liquid hydrogen and liquid oxygen into the shuttle before3 a.m. Friday. The fuelling took place more than an hour later than planned because crews had to replace a nitrogen valve on the launch pad.

Early wake-up call for astronauts

As crews prepared the shuttle for launch, the astronauts themselves prepared for blastoff. They were reportedly out of bed before 1 a.m. ET to get ready. They are expected to take an enormous solar array to the international space station to boost its power capacity.

Atlantis was originally set to launch on Aug. 27 but was delayed when lightning struck the space centre two days before. The launch was rescheduled, but had to be postponed again because of the approach of tropical storm Ernesto. It was delayed early Wednesday when the fuel cell problem arose.

MacLean and five other astronauts have been preparing for more than four years to go into space to perform construction work on the international space station during a mission that is expected to last 11 days.

NASA said the weather forecast looks promising for Friday andsaid there is a 70 per cent chance that it will be clear.