July 4, 2006 — Space shuttle Discovery blasted off its seaside launch pad on Tuesday, on what is expected to be NASA's final bid to test post-Columbia safety upgrades and end a nearly four-year hiatus in space station construction.
Liftoff occurred at 2:38 p.m. ET. The flight is scheduled to last 12 days, though managers are expected to extend the mission by one day. The shuttle is heading toward the International Space Station and is scheduled to dock on Thursday.
"America is ready to return the space shuttle to flight, so good luck and godspeed Discovery," NASA launch director Mike Leinbach said minutes before liftoff.
"I can't think of a better place to be here on the Fourth of July," replied Discovery commander Steve Lindsey. "For all the folks on the Florida east coast, we hope to give you an upclose and personal look at the rocket's red glare."
NASA approved the launch despite a potentially serious problem with the shuttle's fuel tank, and over the objections of its chief engineer and head of safety. The tank, which is covered in foam insulation to prevent potentially hazardous ice buildups, has already been redesigned twice since the 2003 Columbia accident and is slated for additional work.
The launch was delayed twice by rain and clouds at the Kennedy Space Center. Managers faced the prospect of another delay when technicians found a small piece of foam that had broken off insulation covering a bracket holding a fuel line on the tank. Engineers, however, were able to quickly determined that the missing foam would not pose a threat to the shuttle.
Throughout the flight, the shuttle crew will spend hours scanning their ship's heat shield with a laser imager and a using high-resolution digital camera to check for damage from launch debris.
The inspections are a direct result of the Columbia disaster, which was triggered by a piece of falling foam insulation striking and damaging the shuttle's wing during launch. The shuttle was destroyed as it attempted to return through the atmosphere for landing 16 days later, killing seven astronauts.
If any damage is found, the Discovery crew will have options not available to Columbia's astronauts. They can stay aboard the space station for nearly 90 days while NASA prepares a rescue mission, or, if the damage is not serious, they can attempt repairs with experimental patches and fillers.
NASA administrator Michael Griffin decided to proceed with Discovery's launch because even if the worst-case scenario of potential foam debris impacts, the crew would not be in danger. Any more serious problems with the shuttle, however, could mean the end of the shuttle program and severely cripple the half-built space station.
"Foam is a concern. But I very strongly feel that we are not risking the crew for foam in this case, or I wouldn't feel comfortable launching," Griffin said.
"Flying the shuttle is not without risk for many reasons way beyond foam," he added. " I worry that we've spent so much time worrying about foam that we won't worry about other things which could get us. We've tried to address them all."
A successful flight will jump-start the stalled space station program, which now must be completed in four years before the shuttle fleet is retired. The shuttle is the only vehicle that can carry the remaining truss segments, solar arrays and laboratories to orbit.
"We need to get on with things," Griffin said. "I absolutely do not think and do not accept we are being unduly influenced by schedule pressure. But we pay attention to schedule because time is money and that matters."
Engineers and imaging experts will begin analyzing launch videos, pictures and radar from hundreds of instruments immediately following launch. A preliminary indication of how the remodeled tank performed is expected Tuesday night.
