Atlantis looks good to go

Shuttle launch Thursday, weather permitting

Space shuttle Atlantis looks good to go for blast-off Thursday from NASA's Kennedy Space Center in Florida, weather permitting.

The mission to carry Europe's Columbus laboratory to the ISS has twice been delayed by faulty sensors monitoring liquid hydrogen levels in the vessel's fuel tank. The offending devices are designed to prevent the shuttle's engines running dry, provoking an explosion.

Atlantis's commander Stephen Frick said: "We can't afford to let the engines run dry because they tend to come apart."

He continued: "The sensor problem has been nagging us for quite a long time. We were able to pull the hardware out, find out what the problem really is and get a chance to fix it properly so we don't have to worry about it."

Following tests of the sensor connectors, NASA reported (pdf): "Open circuits in the part that connects wires from the interior to the exterior of the liquid hydrogen tank, commonly known as the feed through plate, were identified as the culprit that caused false readings during two launch attempts and a tanking test in December 2007."

NASA's solution was to knock together a modified connector "with the pins and sockets soldered together", and more tests subsequently "verified the adequacy of the new configuration".

NASA also identified a potential problem with a bent cooling system hose in Atlantis's payload bay earlier this week, but technicians "used a special tool to guide the hose back into its storage box while the payload bay doors were closed", as the agency puts it.

Forecasts for 7 February indicate a 40 per cent chance of favourable weather. Lift-off is scheduled for 14.45 EST (19.45 GMT).

During the 11-day mission, the team will install the aforementioned Columbus lab - a task involving three spacewalks - as well as delivering some new experiments and doing a few "maintenance chores".

European Space Agency astronaut Leopold Eyharts will remain on the ISS to oversee the experiments, relieving Daniel Tani who travelled to the station on Discovery's 23 October mission. There are full details here (pdf). ®

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