NASA: Some Atlantis Shuttle Fuel Tank Repairs Complete, New Vessel Due Friday

In Highbay 1 in the Vehicle Assembly Building, the space shuttle Atlantis' orbiter cockpit, nose cone and part of the external tank peak through various levels of scaffolding as work continues to repair the external tank. CREDIT: NASA/Jack Pfaller.

NASA engineers have completed some repairs to the shuttle Atlantis' hail-damaged external fuel tank at the agency's Florida spaceport, where a possible replacement is due to arrive Friday, agency officials reported Thursday.

A barge carrying the new shuttle fuel tank is expected to dock at NASA's Kennedy Space Center in Cape Canaveral, Florida at about 1:00 p.m. EDT (1700 GMT), the space agency said in a mission update, adding that initial repairs to the vital foam insulation covering the lower half of Atlantis' damaged tank are finished.

"Foam repairs on the liquid hydrogen tank, which is located on the bottom of the external tank, are complete," NASA reported. "The focus is currently on repairs to the liquid oxygen tank."

The shuttle tank's liquid oxygen supply resides in the upper portion of the fuel vessel, where engineers have sanded away the damaged foam insulation and plan to spray on new layer of material.

Atlantis' fuel tank sustained thousands of dings during a freak Feb. 26 storm that bombarded the 15-story vessel with golf ball-sized hail at the shuttle's Pad 29A launch site. The damage prompted NASA shuttle managers to delay the planned March 15 launch of Atlantis' STS-117 mission to the International Space Station (ISS) to allow time for repairs or an external tank swap.

Atlantis is currently slated to launch its ISS construction mission no earlier than mid-May if its tank can be repaired swiftly, though a fuel tank change would push the flight into June.

"Right now I know they're working hard to repair the tank at this time," STS-117 mission specialist Steven Swanson told SPACE.com Thursday, adding that workers at NASA's New Orleans-based Michoud Assembly Facility -- where shuttle fuel tanks are built -- are focused ensuring the fixes are sound. "The engineers are working hard at Michoud on the certification of the repairs that they're doing. So that should all hopefully come together some time next week and we'll find out what we'll do."

NASA managers are expected to meet around April 10 to decide whether or not to proceed with a mid-May launch target or switch tanks and aim for June. Atlantis' launch window in May closes around May 21 and reopens around June 8, NASA officials have said.

Commanded by veteran shuttle spaceflyer Rick Sturckow, Atlantis' STS-117 astronauts plan to deliver a new pair of massive ISS trusses and solar arrays during their 11-day construction mission.

Swanson, who will perform one of three planned spacewalks during the STS-117 flight, said the mission's delay has had a silver lining of sorts, allowing he and his crewmates a short break from the frenetic pace of flight training.

"It's all in stride, I think," said Swanson, who joined NASA's Astronaut Corps in 1998 and will make his first spaceflight during STS-117, of the delay. "What's another month of two after nine years?"

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