NASA has postponed the launch of its space shuttle Discovery to no earlier than 4:05 a.m. EST on 30th November, after engineers had to delay launch following a hydrogen gas leak.

The delay will allow engineers and technicians time to diagnose and repair a hydrogen gas leak detected while filling the external tank Friday morning, a NASA press release explains.

Engineers and technicians will also assess a foam crack on the external fuel tank's liquid oxygen intertank flange. The crack was discovered during de-tanking operations.

The leak was found at the Ground Umbilical Carrier Plate, 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.

“We always place safety first,$quot; said 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 hydrogen leak, dicovered two hours into the fuelling operation, is considered serious by NASA managers due to the potential flammability of the gas.

After 26 years of service, the vehicle is due to make one last flight to the International Space Station (ISS) before being retired to a museum, repots claim.

The agency is now planning a launch date on 30th November, to give plenty of time to fix the leak.