NASA Engineers Examine Space Shuttle Discovery Ahead of Repairs
A fuel leak and crack on the space shuttle Discovery's huge external tank has forced NASA to call off any attempts to launch before Nov. 30 – the latest in a series of delays for the spacecraft's final voyage.
Credit: NASA/Troy Cryder

NASA engineers are beginning their examination of the fuel leak that stalled last week's launch of the space shuttle Discovery to the International Space Station.

Engineers are taking steps to remove and inspect the component where the leak was discovered on Discovery's huge orange external fuel tank. Early work to study a 20-inch (51-centimeter) crack in the fuel tank's foam insulation is also planned for this week, NASA officials said.

"Right now they're basically trying to gather as much information as possible before they start actually making repairs for any of the issues that we're working," NASA spokesman Allard Beutel told "It's not a matter of simply making the repairs. They want to know what caused this in the first place."

NASA is now hoping for a Nov. 30 launch date for Discovery's final flight before it is retired along with the rest of shuttle fleet in 2011.

The hydrogen gas leak was detected Nov. 5 as Discovery's 15-story external tank was being filled with liquid oxygen and liquid hydrogen ? the cryogenic propellant that powers the shuttle's three main engines during liftoff and ascent into orbit.

Discovery's fuel tank leak

The leak was in the ground umbilical carrier plate, or GUCP, which is an attachment point between the external tank and a 17-inch (43-cm) pipe that carries gaseous hydrogen safely away from the shuttle to the flare stack, where it is burned off. NASA encountered similar leaks on two previous shuttle missions but wants to understand how the latest event occurred.

Engineers are expected to record measurements as the shuttle stands on its seaside launch pad at NASA's Kennedy Space Center in Florida. An analysis will be performed after the GUCP has been removed, and Discovery's STS-133 mission managers will then assess repair options.

Tank crack concerns

A crack in the foam insulation of the shuttle's external tank was also found during an inspection following Discovery's scrubbed launch.

The roughly 20-inch crack is located in the inner foam on a different part of the tank than the fuel leak. It is more than twice as long as previously thought. NASA initially estimated the crack at 7 inches (almost 18 cm) long, mission managers said. [Photo of the cracked foam]

Beutel said that while work on the leaking fuel line will begin today (Nov. 9), engineers are not expected to begin work on the foam until Wednesday.

Technicians studying the crack will use non-destructive terahertz or X-ray scans to look beneath the foam for any other potential hazards.

NASA is extremely wary of any large cracks in the foam insulation that coats space shuttle fuel tanks, because debris from the cracks pose a danger to the shuttles during flight.

Foam debris that separated during the launch of the space shuttle Columbia in 2003 led to the loss of that shuttle and its seven-astronaut crew as the spacecraft re-entered Earth's atmosphere for landing.

Since then, NASA has instituted measures to reduce the amount of foam on shuttle fuel tanks, and technicians perform several inspections before launch.? Astronauts also inspect their shuttle heat shields for damage while they are in space, using robotic arm-mounted sensors.

While NASA studies the problems, Cmdr. Steve Lindsey and pilot Eric Boe, who flew back to NASA's Johnson Space Center with their fellow STS-133 crewmembers following Friday's launch postponement, planned to return today for a series of training exercises in the agency's shuttle training aircraft.

The next possible time that Discovery can attempt a liftoff to the International Space Station is Nov. 30 at 4:05 a.m. EST (0905 GMT). Discovery is scheduled for an 11-day supply mission to the space station to deliver a humanoid robot helper for the station crew and a new storage room for the orbiting lab.

The STS-133 mission will be Discovery's grand finale in space before being retired. Managing Editor Tariq Malik contributed to this report.