Engineers Inspect Atlantis Shuttle’s Hail-Damaged Fuel Tank

On an upper level of high bay 1 of the Vehicle Assembly Building, technicians move protective material toward the nose cone (foreground) of Atlantis' external tank. The nose cone will undergo repair for hail damage. CREDIT: NASA/George Shelton.

A team of engineers is taking a meticulous look at the hail-damaged fuel tank of NASA's shuttle Atlantis to determine how best to repair its weather-beaten surface for a planned April launch to the International Space Station (ISS).

"We're kind of working our way down the tank to assess it," Harry Wadsworth, a spokesperson for shuttle fuel tank manufacturer Lockheed Martin, told SPACE.com Thursday. "We should have a go-forward plan early next week to take to the space shuttle program."

A freak thunderstorm centered right over NASA's Pad 39 launch complex at the Kennedy Space Center (KSC) in Cape Canaveral, Florida peppered Atlantis' fuel tank with golf ball-sized hail on Feb. 26, gouging thousands of dings in the vessel's vital foam insulation [image].

Atlantis was slated launch its six-astronaut STS-117 crew towards the ISS on March 15, though shuttle mission managers opted to delay the space shot to late April to make repairs.

The shuttle left its Pad 39A launch site on March 4 for the shelter of NASA's cavernous 52-story Vehicle Assembly Building [image]. Once there, work crews surrounded the orbiter's fuel tank with scaffolding in order to reach its pockmarked nose cap, which sits about 184 feet (56 meters) above the Mobile Launch Platform that supports the attached shuttle, fuel tank and twin rocket boosters [image].

Wadsworth said a team of about six tank specialists headed to NASA's Kennedy Space Center in Cape Canaveral, Florida this week from the New Orleans-based Michoud Assembly Facility, where shuttle fuel tanks are manufactured.

Some foam sanding or blending to address extremely minor damage may be performed this week, but the primary goal is to survey Atlantis' fuel tank and draw up a comprehensive repair plan, Wadsworth said.

NASA shuttle workers are also eyeing minor dings to 27 protective heat-resistant tiles on Atlantis' underside. Launch officials have said ricocheting hail may have circumvented the shroud-like Rotating Service Structure at Atlantis' launch pad, which protect orbiters from weather, to cause the dings.

Damage to fuel tank foam insulation has been a prime concern for NASA since 2003, when a chunk of loose foam shook loose during the launch of Columbia and struck the orbiter's left wing. The resulting damage to the Columbia's heat shield led to the loss of the orbiter and its seven-astronaut crew during reentry.

NASA has since redesigned shuttle fuel tanks to reduce the amount of foam shed during liftoff and developed in-orbit inspection procedures, as well as some limited repair techniques, to address the problem in orbit if required. But ensuring a tank is fit to fly in the first place is imperative, NASA officials said.

"What the program has cautioned everyone is, 'Let's let the team go off and do their work,'" Jessica Rye, a NASA spokesperson at KSC, told SPACE.com. "They've got a lot of inspections to do. We want a full story on what the tank team feels needs to be done."

Commanded by veteran shuttle flyer Rick Sturckow, Atlantis' STS-117 astronaut crew is slated to launch no earlier than late April to haul a 17.5-ton addition to the space station's core framework and two starboard solar arrays.

The mission is NASA's first of up to five ISS construction flights slated for 2007, but must wait until after a 10-day ISS crew swap mission to begin with the planned April 7 launch of a Russian Soyuz spacecraft.

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