A recurring technical glitch scuppered NASA’s attempt to launch its space shuttle Discovery as planned on Wednesday. It is not yet clear when the next launch attempt will take place.
The problem appears to lie in one of four fuel sensors that measure the amount of liquid hydrogen in the shuttle’s external fuel tank. The sensor did not provide a signal, says NASA spokesman Allard Beutel. So with two and a half hours left till launch and Discovery's seven astronauts already strapped into their seats in the orbiter, NASA launch director Mike Leinbach decided to delay the launch while a technical team discusses the issue.
Technicians loaded the external tank with 1.9 million litres of cryogenic liquid hydrogen and liquid oxygen earlier on Wednesday morning. This is the first time this particular tank has been loaded with fuel. Two previous fuelling tests were done with the orbiter's original tank, which was swapped out in May.
NASA experienced a similar problem with two of these sensors during the first fuelling test in April. But technicians replaced an electronics box in the orbiter, so officials thought the problem was solved. The sensors worked fine during the second fuelling test in May.
The next launch opportunity is Thursday afternoon, but it is not clear how long this problem will take to fix. The current launch window extends until 31 July and the next opens on 9 September.
“You know, you don’t want to launch until you’re ready,” US Senator Bill Nelson said minutes before the postponement. Nelson flew on the shuttle mission before the Challenger disaster and endured four postponements of his flight.
Weather conditions were also looking pessimistic on Wednesday. Forecasters had said there was a 40% chance of unacceptable launch weather on Wednesday morning. NASA's Kennedy Space Center issued a lightning advisory at 1230 EDT (1630 GMT). But weather officers thought most of the storms would move west of KSC by launch time at 1551 EDT (1951 GMT).
But the weather forecast later worsened to a 60% chance of no-go weather when winds began blowing from the southwest, keeping the storms over the flight zone.
This flight would have been the first shuttle launch since the Columbia accident in February 2003.
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