Nasa called off Wednesday’s launch of Discovery — the first by a US space shuttle since the 2003 Columbia disaster — after detecting a faulty fuel sensor.
The flight was postponed two hours and 20 minutes before the scheduled lift-off. The seven crew members, including Japanese astronaut Soichi Noguchi, had already boarded Discovery.
Discovery will not be launched before Monday, Nasa administrator Michael Griffin told journalists at the Kennedy Space Centre shortly after the lift-off was postponed.
”We have had to scrub the launch for today,” Nasa spokesperson George Diller said.
He said the defective hydrogen fuel sensor could have prevented the shuttle from reaching full power during its ascent into orbit.
The sensor is one of four designed to transmit data to computers on the levels of hydrogen remaining in the main tank, to determine when engines should be shut off during the ascent into orbit.
The sensor did not respond during tests before the launch from the Florida seashore space centre, which had been planned for 3.51pm local time.
As the seven astronauts left the orbiter in their distinctive orange suits, experts gathered to try to determine why the sensor failed.
The incident was the latest of several glitches ahead of the planned lift-off.
Earlier, a system that helps reduce the chance of an explosion during fuelling had to be replaced, delaying the pumping of close to two million litres of liquid hydrogen and oxygen into the shuttle’s massive external tank.
Nasa got a scare on Tuesday when a plastic and foam protective cover fell 20m off one of Discovery‘s windows, damaging tiles on one of the two orbital manoeuvring systems. Experts scrambled to replace the panel containing the tiles.
Worsening weather had also jangled nerves at the Kennedy Space Centre as thunderstorms rolled in.
Nasa has until the end of the month to send the shuttle into orbit so it can hook up with the International Space Station, but there are concerns Tropical Storm Emily, now raging in the Caribbean, could eventually move toward Florida.
Nasa will call off a launch if there are thunderstorms within 37km of the launch pad, since they could affect an eventual emergency landing.
Ground crews also want the skies on the shuttle’s trajectory to be clear so they can monitor the ascent.
During the planned 12-day mission, the seven astronauts, led by Commander Eileen Collins, are scheduled to test changes made since Columbia burst into flames upon reentry into the Earth’s atmosphere on February 1 2003. Nasa has grounded its shuttle fleet since then.
Crews on the ground also will be assessing the improvements, and will keep a close eye on the external fuel tank’s new insulation system.
At Columbia‘s launch, a small piece of insulation broke off and struck the orbiter’s left wing, causing a crack that allowed superheated gases to penetrate the structure just minutes before the planned landing.
More than 100 cameras are installed on the ground and aboard two airplanes, to capture Disvovery‘s first two minutes of ascent.
During one of three planned spacewalks, Japanese astronaut Noguchi and his US counterpart Stephen Robinson are due to test repair techniques.
The spacecraft is also to deliver vital supplies and equipment after docking with the International Space Station, whose crew will photograph Discovery‘s underside. — AFP
