The US space agency plans to launch the space shuttle Endeavour after stormy weather forced the fourth postponement of its mission to the International Space Station.
"Looks like the team is ready but the weather is not. At this time we are no-go," the US space agency's launch director Pete Nickolenko said with the crew aboard and little more than 10 minutes to go before the planned takeoff on Sunday.
The shuttle launch was rescheduled for Monday at 6:51 pm (2251 GMT), Nickolenko said.
However, forecasters said the likelihood of favorable conditions was just 40 percent, far below the forecast leading up to Sunday's scrapped attempt when meteorologists predicted a 70 percent chance of good weather.
The cancellation was forced by a storm system that developed late afternoon near the launch site in Florida and gradually moved within 20 miles (32 kilometers) of launchpad 39A, where the Endeavour and its seven-astronaut crew were waiting to take off.
|The space shuttle Endeavour on its launch pad at the Kennedy Space Center in Cape Canaveral, Florida|
NASA officials waited until just minutes before liftoff to scrub the launch, hoping that a sea breeze might shift the weather system further afield, as has happened before.
But as the minutes ticked down, there were reports of lightning strikes within miles of the Kennedy Space Center, forcing the cancellation.
Lightning strikes were responsible for the third of four delays to Endeavour's mission to the International Space Station (ISS) to assemble the Japanese Kibo laboratory.
A Friday night storm produced at least 11 lightning strikes that hit the shuttle's pad, but did not damage the shuttle.
Takeoff had been delayed previously twice after the discovery of potentially hazardous fuel leaks, apparently caused by a misaligned plate linking a hydrogen gas vent line with the external fuel tank.
The US space agency said the problem had been fixed, and had filled Endeavour's external fuel tanks with some two million liters (half a million gallons) of low-temperature liquid hydrogen on Sunday before the launch was scrapped.
Endeavour's crew -- including six Americans and one Canadian -- are expected to install a platform on the ISS for astronauts to conduct experiments in the vacuum of space, 350 kilometers (220 miles) above Earth's surface.
Canadian Julie Payette, an electrical and information engineer, is the only woman on board.
She has been into space before, as have two other members of the crew, including shuttle commander Mark Polansky.
The crew's four other members will be on their maiden space voyage.
American aerospace engineer Tim Kopra, 46, will replace Japanese astronaut Koichi Wakata, spending several months aboard the floating space station.
He would be the latest addition to the permanent crew of the ISS, which is a joint collaboration between 16 different countries.
The astronauts were also expected also undertake repair and replacement work, including installing six new batteries in the ISS.
That mission will require two astronauts to conduct five space walks totaling 32.5 hours.
Kibo's two pressurized modules were attached to the ISS in 2008, along with the European lab Columbus.