Sensor glitch delays space shuttle launch

Nasa postponed the launch, scheduled for Thursday, of the United States space shuttle Atlantis after discovering a problem with a sensor in the spacecraft’s fuel tank, officials said.

The US space agency planned to try again on Friday to launch Europe’s long-delayed Columbus science laboratory to the International Space Station.

The problem that derailed Thursday’s launch attempt involved two of four sensors in the ship’s fuel tank that monitor levels of liquid hydrogen. The shuttle uses more than 2,273-million litres of cryogenic hydrogen and oxygen for its 8,5-minute sprint into orbit.

The sensors are a critical part of a back-up safety system to shut down the shuttle’s main engines once the ship reaches space or if a problem occurs after lift-off. If the engines continued to run once the fuel supply was gone, an explosion could destroy the ship.

Nasa wrestled with a series of fuel-tank sensor problems as it attempted to resume shuttle flights following the 2003 Columbia accident. The first post-Columbia mission in July 2005 was delayed by 13 days due to sensor glitches.

Engineers traced the problem to a bad batch of sensors and replaced the suspect devices.

Tucked inside Atlantis‘s cargo bay as it waited for another launch opportunity was the European Space Agency’s (ESA) primary contribution to the $100-billion space-station programme—an 8,2m-long, 4,6m-diameter laboratory named Columbus.

ESA has waited patiently for its launch for more than five years. Its initial launch was postponed when Nasa grounded the shuttle fleet for safety upgrades after the Columbia disaster.

Columbus “is our cornerstone, our baby, our module, our laboratory”, said Alan Thirkettle, ESA’s space station manager.

Columbus can hold 10 telephone booth-sized racks of experiments. One called Biolab will be used for experiments on microbes, cells, small plants and insects. An experiment using salmonella bacteria carried on Atlantis in 2006 showed the germs become more virulent in low gravity.

Another will be used to study the effects of long-duration spaceflight on the human body, including the brain and heart, while a third will test the dynamics of fluids in zero gravity.

Columbus will become the second dedicated laboratory at the outpost and Europe’s first permanent base in space.—Reuters

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