Weather delays shuttle liftoff

Source: news.com.au

WITH the seven astronauts aboard and the countdown clock showing minutes to go, NASA has announced the postponement of its shuttle launch.

"We have scrubbed our launch attempt for today," said NASA launch spokesman Bruce Buckingham at the Kennedy Space Centre in Cape Canveral, Florida. Officials with the US space agency scheduled a launch attempt for 3.26pm tomorrow (0526 AEST Monday).

"The primary concern was for anvil clouds within 32.2km of the landing facility," Mr Buckingham said.

The 12-day mission, which will bring critical supplies and equipment to the International Space Station, is considered crucial for the future of the space program as it will determine whether NASA has improved shuttle safety three years after the Columbia disaster.

Shortly before launch, NASA found that a thermostat controlling the heater of a thruster at the tail of the shuttle had failed, officials said. But John Shannon, the chairman of the mission management team, decided it will not be an impediment for the mission.

The major concern for this mission has been the possibility of debris shedding from the shuttle's external fuel tank yet again.

Columbia's demise was caused by loose foam that pierced its protective heat shield during liftoff.

NASA spent more than $US1 billion ($1.36 billion) to fix the problem, but foam still fell off the tank during Discovery's launch last year, the first since the tragedy.

The debris missed the shuttle, but the incident prompted the space agency to ground the spacecraft until now.

NASA Administrator Michael Griffin defended his controversial decision to schedule today's launch despite opposition within his staff, and he expressed confidence that no large chunks of foam would peel off this time around.

"We are not expecting that. I do not feel vulnerable," he said, although he underscored that flying into space was never free of danger.

"Flying a shuttle is not without risk for many reasons," Mr Griffin said.

"In fact, I worry that we spend so much time worrying about foam that we won't worry about other things which could get us," he said.

"Foam is a concern, but I very strongly feel that we are not risking the crew for foam in this case, or I wouldn't feel comfortable launching," Mr Griffin added.

NASA chief safety officer Bryan O'Connor and chief engineer Chris Scolese had called for a six-month delay to the launch to redesign foam on the fuel tank.

But the two officials backed the launch after NASA said the astronauts could take refuge on the ISS and wait for a rescue mission should the shuttle suffer irreparable damage.

NASA has installed more than 100 cameras to detect any loose debris, and Discovery will perform a back flip before docking to the ISS so the space station's crew can take pictures to detect any damage to the shuttle's heat shield.

The images will allow officials to better understand the phenomenon and fix it, Mr Griffin said.

"This is the first step back toward restoring the shuttle to regular (flights) ... that will allow us to finish the space station project," Mr Griffin said.

"Quite frankly, I think if we are unable to complete the project that we have before us, the space station, we will have a certain lack of credibility in encouraging others to join us in the exploration of Mars," Mr Griffin said.