NASA Mulls Shuttle Fuel Tank Repair Plan

Work crews sand red dye from the surface of the hail-damaged external fuel tank of NASA's space shuttle Atlantis to help repair thousands of dings gouged into its foam insulation-covered surface. CREDIT: NASA/Jim Grossman.

NASA mission managers are meeting today to discuss of fuel tank repair efforts for the agency's delayed shuttle flight to the International Space Station (ISS).

The agency-wide video conference is evaluating ongoing repair work to the space shuttle Atlantis' external tank, which suffered extensive damage [image] during a freak February hail storm that delayed the orbiter's STS-117 mission to no earlier than late April or May. If tank experts decide to replace the damaged tank with a pristine one, the swap would push the spaceflight to June, NASA has said.

"It's an opportunity to be able to [update] everybody at once on where the engineering analysis is," NASA spokesperson Kyle Herring, of the Johnson Space Agency in Houston, told SPACE.com Tuesday of today's meeting.

Shuttle mission managers are expected to discuss today's meeting during a press briefing slated for no earlier than 5:00 p.m. EDT (2100 GMT).

NASA is hoping to launch Atlantis towards the ISS sometime between late April and May 21, after which the angle of the Sun on the station's solar arrays would hinder the outpost's ability to support an incoming shuttle crew until June 8, with that flight window running through about July 19, Herring said.

Commanded by veteran shuttle flyer Rick Sturckow, Atlantis' STS-117 mission is NASA's first of several ISS construction flights planned for 2007. The mission was slated for a March 15 liftoff from the U.S. space agency's Kennedy Space Center in Florida before a Feb. 26 storm peppered Atlantis' external tank with golf ball-sized hail, gouging thousands of tiny divots in its foam insulation-covered surface [image].

Sturckow and his five STS-117 crewmates must now wait until after a space station crew swap, expected to be complete by April 20, to launch towards the ISS. Their 11-day mission will deliver a new set of starboard solar arrays to the ISS.

External tank engineers have been hard at work sanding smooth the most minor hail-spawned dings on Atlantis' tank, though more serious damage will require pouring or hand-spraying new foam material to the afflicted areas [image].

Prior to launch, shuttle fuel tanks are filled with some 526,000 gallons of super-chilled liquid oxygen and liquid hydrogen propellant, which feeds an orbiter's main engines during liftoff. A protective layer of foam insulation prevents ice from building up on the tank's aluminum surface and adds some protection from aerodynamic stresses experienced during the 8.5-minute ride toward orbit.

NASA has kept close watch on fuel tank foam integrity since the 2003 loss of the shuttle Columbia and its seven astronaut crew. A briefcase-sized chunk of foam fell from Columbia's tank during launch, damaging the orbiter's left wing heat shield and leading to its destruction during reentry.

Since then, NASA as made a series of modifications to limit the amount of fuel tank foam shed during liftoff, but there was likely little the space agency could do to guard against the type of storm that struck Atlantis on Feb. 26, agency officials have said.

William Gerstenmaier, NASA's associate administrator for space operations, told a congressional subcommittee last week that hail storm was so localized over Atlantis' Pad 39A launch site that, had the shuttle stood atop the nearby Pad 39B site, it would likely not have suffered as much damage.

"It was an extremely isolated storm," Gerstenmaier said.

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