Gas leak postpones space shuttle launch

By Irene Klotz

CAPE CANAVERAL, Florida (Reuters) - NASA canceled plans to launch space shuttle Endeavour on a construction mission to the International Space Station on Saturday due to a potentially dangerous hydrogen leak.

The leak was found as technicians neared completion of the loading of 500,000 gallons (1.9 million liters) of liquid hydrogen and liquid oxygen into the shuttle's fuel tank for a launch attempt at 7:17 a.m. EDT.

"There's no way we could have continued," said NASA launch director Mike Leinbach. "Hydrogen is a very volatile commodity."

The problem is similar to a hydrogen leak that occurred while shuttle Discovery was being prepared for launch in March. NASA discovered a problem with a line that vents gaseous hydrogen from the fuel tank.

Technicians replaced the faulty equipment and the shuttle was successfully launched four days later.

NASA is tentatively retargeting Endeavour's launch for Wednesday, but that would mean the agency would have to delay launch of its robotic moon probe, the debut mission of a new exploration initiative aimed at returning astronauts to the moon by 2020.

Both the shuttle and the Lunar Reconnaissance Orbiter's Atlas rocket use safety and support services from Cape Canaveral Air Force Station, which needs two days to configure equipment for different launch vehicles. LRO is slated to fly on Wednesday.

"We had pretty much agreed ahead of time that we would not bump them off the range," said Mike Moses, the shuttle manager at Kennedy Space Center. "But nothing is a foregone decision."