Shuttle 'buttoned' as clock ticks

By Paul Rincon
BBC News science reporter, at Kennedy Space Center

Discovery is set for a closely scrutinised launch

Nasa has said space shuttle Discovery is "buttoned up" and ready to fly as the launch countdown clock ticks.

Officials said they were "tracking no significant issues" as engineers made final preparations for lift-off from the Kennedy Space Center on Wednesday.

But they are watching the weather; a tropical depression to the south could turn into a hurricane in the next few days, meteorological experts say.

Discovery's mission is the first since Columbia broke apart in 2003.

We realise that the whole world will be looking at us on launch day Stephanie Stilson, Nasa

This will be the most closely scrutinised shuttle launch ever. The shuttle will be tracked by cameras and radar to inspect for any debris that may damage the vehicle as it launches.

Unpredictable weather

"All of our hardware is onboard Discovery," said Scott Higginbotham, STS-114 payload manager. "We're buttoned up and ready to go."

But the unpredictable July weather could yet be an issue for launch.

Shuttle weather officer Kathy Winters told reporters that a weather system known as Tropical Depression 5 to the south could yet turn into a hurricane, to be known as Emily.

"We are not currently looking at any major issues that threaten the 13th. Obviously, weather is an unknown that we always have to deal with," vehicle manager Stephanie Stilson told the BBC News website.

"There are some paperwork-type issues that are still open. There is a slight chance - not very likely - that something will come out of the paperwork. But right now, we have very high confidence for the 13th."

Cameras are positioned on the ground, on planes, on the shuttle itself and on the International Space Station at different stages of flight to inspect for any possible damage.

According to US newspaper reports, also watching closely on 13 July will be a House and Senate delegation, as they consider Nasa's $16.6bn budget.

High expectations

Expectation weighs heavy on all involved in preparing the shuttle's return to flight.

"We realise that the whole world will be looking at us on launch day to make sure we're doing the right thing," said Stephanie Stilson. "It's important to Nasa, it's important to our government, it's important to our country and it's important to our international partners."

The window for launch will open at 1545 EDT (2045 BST; 1945 GMT) on Wednesday 13 July, and ground controllers will target the middle of this window - 1551 EDT (2051 BST; 1951 GMT) - for lift-off.

The mission is scheduled to last 12 days, with landing set for 1100 EDT (1600 BST; 1500 GMT) on 25 July at the Kennedy Space Center.

At 1530 EDT (2030 BST; 1930 GMT) on Monday, workers were to begin loading reactants into the shuttle's fuel-cell storage tanks, to provide the vehicle with power in orbit.

Loading of the shuttle's external fuel tank with cryogenic propellants to blast it beyond the atmosphere will begin at 0600 EDT (1100 BST; 1000 GMT) on Wednesday, approximately nine hours before launch.