By Irene Klotz
CAPE CANAVERAL, Florida (Reuters)
- NASA cancelled 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
litres) of liquid hydrogen and liquid oxygen into the shuttle's
fuel tank for a launch attempt at 7:17 a.m. EDT (12:17 p.m. British
time).
"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 Centre. "But nothing is
a foregone decision."
NASA had reserved three days for
launch attempts of LRO, which also includes a payload designed to
crash into a crater on the moon to look for signs of
water.
NEXT LAUNCH WINDOW
If LRO misses its launch window
next week, the flight would have to be rescheduled for the end of
the month, which in turn would impact other spacecraft scheduled to
fly on future Atlas rockets.
"There are a lot of factors in
play," Moses said.
Endeavour is carrying a
Japanese-built porch that will be installed on the station's $2.4
billion (1.4 billion pound) Kibo complex, Japan's primary
contribution to the $100 billion station program.
The lab includes a robot arm and a
small airlock so science experiments can be installed outside the
station and retrieved without the need for spacewalks by crew
members.
Endeavour also is carrying
laboratory racks, experiments, supplies and spare parts that will
be stored aboard the outpost in preparation for when the shuttle is
no longer flying.
NASA has eight shuttle missions
remaining to complete construction of the station. It plans to
retire the three-ship fleet at the end of 2010.
The Endeavour crew plans to spend
12 days at the station and conduct five spacewalks to install the
porch, replace batteries and tackle a long list of maintenance
tasks.
The mission is NASA's first since
the station's live-aboard crew was expanded to six members from
three last month.
When the shuttle crew arrives, it
will bring the total number of people aboard the space station to a
record 13.
(Editing by Jim Loney and Sandra
Maler)