NASA managers will not decide until next month on a date for Atlantis' next launch, giving technicians more time to assess hail damage to the space shuttle's external fuel tank, officials said.
Atlantis originally was scheduled to lift off last week, but the launch was postponed after golf-ball-size hail caused thousands of dings on foam insulation on the fuel tank as the shuttle sat on the launch pad last month.
Bill Gerstenmaier, associate administrator for space operations, said Wednesday that NASA managers probably would wait until April 10 before deciding whether to use the current tank - which would leave open the possibility of flying in May - or swap it out with another tank - which would push back the next try until June.
"We can get some more analysis done; then we will have enough data to make a good decision," Gerstenmaier said.
Technicians at the fuel tank's manufacturer in Louisiana want time to practice applying foam on a mock-up of its nose cone before they apply it in Florida to the real tank, which is still attached to Atlantis and two solid rocket boosters. They also want to test it to make sure the new foam can withstand heat from the launch.
The foam is used to prevent dangerous ice from building up on the tank during fueling on the launch pad.
The space shuttle was rolled off the launch pad and sent back for repairs to the Vehicle Assembly Building. Technicians have spent two weeks erecting scaffolding around the external tank and sanding down some parts of the foam insulation.
The fuel tank has about 2,500 dings, of which 1,600 may need to be filled with new foam. Technicians can sand down some of the other dings - an easier repair.
"If it becomes uncertain that we can make this tank a good tank, then we will swap to a new one," said Wayne Hale, space shuttle program manager. "The whole goal is to have a good tank."
Atlantis' launch has to come after a Russian Soyuz vehicle completes a mission to the international space station in the first part of April.
Despite the delay, Hale said he is confident the space agency can pull off four space shuttle flights this year to continue construction on the international space station. NASA originally had hoped to fly five shuttle missions this year, but the extra flight will be bumped into next year's schedule, he said.
"The overall manifest will have a ripple effect of several months, but we will catch up about the middle to the end of next year," Hale said.
The insulating foam is of special concern to NASA since a chunk of it flew off during space shuttle Columbia's launch in 2003 and struck the orbiter. The damage allowed fiery gases to penetrate Columbia during re-entry, breaking up the craft and killing its seven astronauts.
NASA redesigned the external tank, removing large amounts of foam, before last year's three successful shuttle missions. The space agency plans another design change to the tank before the shuttle program ends in 2010.