Thunderstorms threaten Discovery's second launch bid

NASA prepared for a new attempt Sunday to launch the Discovery shuttle on a critical mission for the US space program, but nearby thunderstorms threatened the lift-off again.
The seven astronauts slipped into their orange spacesuits after ground crews filled the shuttle's huge external fuel tank for the 3:26 pm (1926 GMT) launch despite the bad weather at the Kennedy Space Center in Cape Canaveral, Florida.
The five men and two women will fly to the International Space Station (ISS) on a mission aimed at improving shuttle safety three years after the Columbia disaster.
But there was a 70 percent chance the weather would force another delay after storm clouds scuttled Saturday's launch, said NASA spokesman George Diller. Apart from weather concerns, officials saw "no constraints" to launch, he added.
NASA had said that it would skip a day and try to launch Tuesday if Sunday's lift-off is also canceled. But Diller said the mission management team will meet to consider launching Monday if lift-off is canceled.
The ISS mission is scheduled to last about 12 days, but NASA wants to extend it by a day. Discovery has a July 1-19 launch window. If the launch gets the green light, the astronauts will take critical supplies to the ISS, perform at least two space walks, and carry out tests on new equipment and procedures to improve shuttle safety in just the second flight since the Columbia tragedy.
Columbia's demise was caused by a piece of foam that peeled off its external fuel tank during lift-off and pierced the shuttle's protective heat shield. Debris also shed from Discovery's tank in last year's first post-disaster flight but missed the shuttle. Still, NASA grounded the shuttle fleet until now to make further modifications to the troublesome fuel tank.
NASA Administrator Michael Griffin again defended his controversial decision to launch the spacecraft despite concerns expressed by his top safety offical and chief engineer.
"I had spent an awful lot of time of my own studying the issue very carefully, because I knew it was going to be controversial, and my analysis of it convinces me that the chances of damaging the orbiter are quite small," Griffin told Fox News Sunday.