NASA will not attempt to launch the space shuttle Discovery until 30 November at the earliest, the US space agency says, after a week of aborted attempts to send the shuttle on its final mission.
The last straw came 5 November when a hydrogen gas leak was detected while filling the external fuel tank.
The leak was at the Ground Umbilical Carrier Plate (GUCP), an attachment point between the external tank and a 7-inch pipe that carries gaseous hydrogen safely away from Discovery to the flare stack, where it is burned off. Two previous shuttle missions in 2009 - Discovery's STS-119 mission and Endavour's STS-127 - had similar problems, NASA says.
While emptying the fuel tank, engineers also discovered a foam crack on the external fuel tank's liquid oxygen intertank flange.
"We always place safety first," says NASA Associate Administrator for Space Operations Bill Gerstenmaier. "It is essential we repair this hardware before we fly the mission, and we will take the time to properly understand and fix the failure before we launch."
The soonest Discovery can be launched is 4:05 EST on 30 November, NASA says. The next launch window will last through 5 December.
The 11-day mission - the 133rd for the shuttle programme and a record 38 for Discovery - will deliver a pressurized logistics module called Leonardo to the 10-year-old International Space Station (ISS). Leonardo, built by the Agenzia Spaziale Italiana, will be permanently attached to the space station and used to transfer cargo to and from the station. The shuttle will also carry Robonaut 2, a 300lb (136kg) humanoid robot developed by NASA, making its first trip into space for testing.
After 26 years of service, Discovery has faced a string of problems trying to get off the ground for its final flight. The original September launch was initially pushed back when payloads to be delivered to the ISS were not ready on time.
Then the planned 1 November take-off was repeatedly scrubbed, first to repair leaking helium and nitrogen gas lines on the shuttle's orbital manoeuvring system pod, which took longer than expected. Then, due to electrical problems during a routine engine power-up and check-out and finally because of weather.
Source: Flight International
