Engineers inspecting the shuttle Discovery's external tank following Sunday's launch scrub found the crack in the tank's foam insulation near a bracket holding a 17-inch oxygen feed line in place, reports CBS News Space Consultant Bill Harwood. Some engineers believe the crack must be repaired but senior managers say a variety of options are on the table, from fly as is to making repairs.
Engineers later found a small piece of foam insulation resting on the surface of Discovery's mobile launch platform that Harwood confirms was associated with the crack.
The inspectors found the crack, which was 8 inches deep, in the foam on a bracket near the top of the external fuel tank.
"We don't know if it's a problem or not," NASA spokesman George Diller said Monday.
It is not yet known what might have caused the crack, although extreme temperature differences because of the presence of super-cold propellants could have played a role, Harwood reports.
Officials were meeting to determine whether it could be fixed for a Tuesday liftoff.
If NASA decides to go ahead with Tuesday's launch, it would be the first manned launch by the United States on the nation's birthday, and only the second liftoff of a space shuttle since the 2003 Columbia disaster.
NASA Administrator Michael Griffin had decided the shuttle should go into orbit despite the concerns of two top agency managers who wanted additional repairs to the foam insulation.
The space shuttle Columbia was brought down in 2003 by a chunk of flyaway foam that damaged its wing, and another piece of foam broke off Discovery's redesigned tank last July, barely missing the shuttle.
Stormy weather prevented NASA from launching Discovery for the second day in a row Sunday, extending a yearlong grounding of the space shuttle prompted by persistent trouble with the fuel-tank foam.
Launch officials said they would try again Tuesday, on the Fourth of July, after giving the work force some rest and a chance to replenish the shuttle's on-board fuel. The weather was expected to improve by Tuesday, although rain was still in the forecast.
Launch director Mike Leinbach had said it will be tight getting Discovery ready for a Tuesday afternoon launch — only the second liftoff of a shuttle since the 2003 Columbia disaster — and that any thunderstorms on Monday could put his team behind.
He halted the countdown just an hour after the seven astronauts boarded the fueled spaceship.
"Looking out the window it doesn't look good today," shuttle commander Steven Lindsey radioed from the cockpit. He noted that July Fourth would be "a good day to launch." It would be the first time NASA has ever launched a crew on the holiday.
The afternoon sky was considerably darker than on Saturday and left NASA with little choice but to call off the flight to the international space station. Thunderstorms were moving in quickly from the west, and lightning was detected within a few miles of the launch pad. The astronauts rode back to crew quarters in the rain.
The back-to-back delays cost NASA an estimated $2 million in overtime pay and fuel costs.
"After a year of preparation and after a very careful countdown, you don't want to get into a rush and do something that is not smart from a weather standpoint," said deputy shuttle program manager John Shannon, chairman of NASA's mission management team. "Nobody is going to remember that we scrubbed a day or two days a year from now. But if we go launch and get struck by lightning or have some other problem, that will be very memorable."
Shannon said he told his team, "What a great gift NASA could give to the nation to return the shuttle to operation on Independence Day."
"If the weather is good, that's exactly what we'll do," he said.