Engineers performing a routine inspection of the tank discovered a piece of insulating foam that had broken off. The dislodged foam - a triangular piece about 3 inches on a side - was covering a bracket that holds the tank's liquid oxygen feed line in place.

At a news briefing Monday, John Chapman, who is the shuttle external tank project manager, said engineers think the incident probably occurred because of thermal flexing that took place either during or after the removal of the super-cooled LOx from the tank.

"We have a good shot at launch tomorrow - if we can resolve this particular problem," said Mike Leinbach, the shuttle launch director. He added that mission team members would meet again late Monday to assess the situation further.

NASA already had postponed Discovery's launch twice - first on Saturday and again on Sunday - due to threatening weather in the vicinity of the shuttle launch pad. As of midday Monday, however, the weather reports predicted a 60-percent chance of favorable conditions on Wednesday, dropping to 40 percent on Thursday.

Ever since the fuel tank's foam insulation was found to have caused the 2003 shuttle Columbia disaster - a piece of foam weighing about 1.5 pounds broke off during launch and punched a large hole in the leading edge of the orbiter's left wing - NASA engineers have been struggling with ways to make the material more secure.

To date, the agency has spent more than $1-billion to fix the problem. Yet in July of last year, another piece of foam fell off Discovery's tank during launch, although it missed hitting the shuttle.

NASA Administrator Michael Griffin has said repeatedly he is confident that no large pieces of foam will break off Discovery's tank when it launches again.

"As far as what happened yesterday and today, the team really performed in exemplary fashion and got the vehicle ready to go and the crew ready to go," said John Shannon, the shuttle's mission management team chairman. "It was that one thing that we really don't control - the weather - it's what kept us from launching."

Unless NASA officials decide otherwise overnight, they will try to launch Discovery at 2:38 p.m. Eastern Time on Tuesday. If the weather cooperates, the launch would be the first time NASA has sent a shuttle into space on a U.S. national holiday.

Discovery's crew includes five men and two women astronauts. They are scheduled to fly to the International Space Station on a 12-day mission intended to bring supplies and equipment to the orbiting facility and to advance its construction.

Discovery will carry 2.5 tons of supplies to the ISS, as well as the Italian-built Leonardo science module. Two members of the crew, Mike Fossum and Piers Sellers, are scheduled to undertake at least two spacewalks.

If the attempt fails on July 4, Discovery's launch window continues until July 19.

related AFP News Wire report

NASA Keeps Discovery Launch On Track Despite Foam Crack In External Tank

NASA pressed ahead with preparations to launch the Discovery shuttle on Tuesday even as inspectors analyzed a crack in the insulating foam on its troublesome external fuel tank.

"Right now we have a good shot of launch tomorrow if we can clear this particular issue," shuttle launch director Mike Leinbach told reporters Monday at the Kennedy Space Center in Cape Canaveral, Florida.

Inspectors found the five-inch (12.5 centimeter) long crack overnight after the tank was emptied of its liquid hydrogen and liquid oxygen fuel, officials said.

A three-inch (7.6 centimeter) triangular piece of foam also fell off, but debris of that size would not have damaged the shuttle during liftoff, said mission management team chairman John Shannon.

"It is less than half the size that can cause damage to the orbiter," Shannon said.

Launch preparations will go on as planned, but inspectors will continue to look at the fissure and analyze it, he said.

NASA officials will meet later Monday to discuss the findings, to "try to clear all our concerns and go launch tomorrow."

The crack may have been caused by condensation when the fuel tank was emptied of its extremely cold propellant after Sunday's launch was cancelled due to bad weather, officials said. The first launch attempt on Saturday was also scrapped due to storm clouds.

The orange-hued fuel tank's foam insulation has perplexed NASA ever since the 2003 Columbia disaster, which was caused by loose foam that pierced the shuttle's heat shield during liftoff. The damage caused Columbia to break apart as it returned to Earth.

The US space agency spent more than a billion dollars to fix the problem, only to see a piece of foam fall off Discovery's fuel tank in the first post-tragedy launch in July 2005. The debris missed the shuttle, however.

Nevertheless, the space agency grounded its 25-year-old fleet last year after the mission.

Prior to the current planned launch, NASA Administrator Michael Griffin expressed confidence that no large chunks of foam would shed from Discovery's second mission since Columbia.

Discovery's five men and two women astronauts are due to fly to the International Space Station (ISS) on a mission aimed at improving shuttle safety.

During the 12-day flight, the astronauts will test new procedures to boost safety as well as deliver critical equipment and supplies to the ISS.

They will drop off European Space Agency astronaut Thomas Reiter of Germany, who will join the ISS's two other crew members for a long-term stay, and will undertake two space walks.

NASA hopes to extend the mission by a day to conduct a third space walk to test new repair techniques.

The space agency has installed cameras on the shuttle and its fuel tank to detect any loss of foam during liftoff. The shuttle's heat shield will then be photographed as it approaches the ISS.

Griffin, the NASA chief, has said the Discovery mission was crucial to returning to regular shuttle flights. He wants to conduct four shuttle missions a year to complete the space station by 2010, when the 25-year-old fleet is scheduled to retire.

He decided to go ahead with the launch despite objections in his own staff.

NASA chief safety officer Bryan O'Connor and chief engineer Chris Scolese had called for a six-month delay to the Discovery launch to redesign foam on the fuel tank.

But the two officials backed the launch after NASA said the astronauts could take refuge on the ISS and wait for a rescue mission should the shuttle suffer irreparable damage.

NASA was also watching the weather for Tuesday's launch, with a 40 percent chance it could force another delay. Discovery's launch window ends July 19.

Related Links
Shuttle at NASA

Memory Foam Mattress Review

SPACE MEDIA NETWORK PROMOTIONS Solar Energy Solutions Tempur-Pedic Mattress Comparison ... Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News