Space shuttle Discovery blasts off on its final flight

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CAPE CANAVERAL, Fla. — After a last-minute glitch, the space shuttle Discovery lifted off Thursday on its final voyage, heading for the International Space Station with six astronauts and a humanoid robot.

The countdown proceeded smoothly until there were just minutes left before liftoff: Air Force range safety officers reported that their command system display wasn't working, which could have forced a halt to the count.

"Calm down," shuttle launch director Mike Leinbach told his colleagues. He asked for some extra time to get the problem fixed — and received the go-ahead. The countdown had to be held at T-minus-5 minutes, but the range safety glitch was resolved with just a couple of seconds to spare in Thursday's launch window.

It was an extra bit of drama for a mission that was initially scheduled for launch last November. At that time, fueling problems held up the launch, forcing months of repairs. No such problems arose this time.

"Enjoy the ride," mission control told Discovery commander Steven Lindsey as the countdown clock wound down toward zero.

"For those watching, get ready to witness the majesty and power of Discovery as she lifts off one last time," Lindsey replied.

Launch came at 4:53 p.m. ET, three minutes later than scheduled. "The final liftoff of Discovery," launch commentator Mike Curie said, "a tribute to the dedication, hard work and pride of America's space shuttle team."

Debris flies off fuel tank
A video camera mounted on Discovery's fuel tank showed several bits of debris flying through the picture during the shuttle's ascent, including what appeared to be an 8-by-10-inch patch of foam insulation that struck the orbiter almost four minutes after launch.

Foam debris loss is of particular concern because in 2003, the shuttle Columbia's wing was hit by a piece of flying foam. Investigators say the resulting damage led to the breakup of that shuttle when it re-entered the atmosphere 16 days later. All seven of Columbia's astronauts were killed, and NASA grounded the shuttle fleet for more than two years afterward.

Bill Gerstenmaier, NASA's associate administrator for space operations, told reporters that Thursday's foam strikes occurred after the risky part of Discovery's ascent. "They're not a concern to us," he said. The shuttle's protective tiles are due to get a detailed inspection on Friday.

Discovery is scheduled to dock with the International Space Station on Saturday, delivering tons of supplies, a new orbital closet and a humanoid robot named Robonaut 2.

World's most traveled spaceship
Discovery is NASA's most traveled space shuttle, putting in nearly three decades of service. Now it's slated to become the first of NASA's three remaining shuttles to retire.

This is the 39th flight for Discovery, which has logged 143 million miles (230 million kilometers) since its first mission in 1984. After retirement, the orbiter is expected to go on display at the Smithsonian Institution's Udvar-Hazy Center, an annex of the National Air and Space Museum.

NASA estimated that 40,000 guests were on hand for Discovery's farewell launch, including a small contingent from Congress and Florida's new governor, Rick Scott. Watching with special interest from Houston was astronaut Timothy Kopra, who was supposed to be the flight's lead spacewalker. He was hurt in a bicycle crash last month and was replaced by Stephen Bowen, who will become the first astronaut to fly back-to-back shuttle missions.

In addition to Lindsey and Bowen, Discovery's crew includes pilot Eric Boe, spacewalker Benjamin Alvin Drew Jr. and mission specialists Michael Barratt and Nicole Stott. All six astronauts are veterans. Stott and Barratt served long-term stints on the space station in 2009.

Onlookers flock to watch launch
Roads leading to the launch site were jammed with cars parked two and three deep; recreational vehicles snagged prime viewing spots along the Banana River well before dawn. Businesses and governments joined in, their signs offering words of encouragement. "The heavens await Discovery," a Cocoa Beach church proclaimed. Groceries stocked up on extra red, white and blue cakes with shuttle pictures. Stores ran out of camera batteries.

The launch team also got into the act. A competition was held to craft the departing salutation from Launch Control; Kennedy Space Center's public affairs office normally comes up with the parting line. Souvenir photos of Discovery were set aside for controllers in the firing room. Many posed for group shots.

Leinbach noted that it would be "tough" to see Discovery soar one last time. "What will be most difficult will be on landing day when we know that that's the end of her mission completely," he said.

Discovery will spend 11 days in orbit — on top of the 352 days it's already spent circling the planet — and will rack up another 4.5 million miles (7.2 million kilometers).

Its achievements include delivering the Hubble Space Telescope to orbit, carrying the first Russian cosmonaut to launch on a U.S. spaceship, returning Mercury astronaut John Glenn to orbit, and bringing shuttle flights back to life after the Challenger and Columbia accidents.

"She's been an amazing machine," Leinbach said Wednesday. "She's done everything we've asked of her."

Discovery's crew will deliver and install a closetlike compartment full of space station supplies. The Italian-made module was named Leonardo, after the Italian artist/inventor Leonardo da Vinci.

Packed inside the compartment is Robonaut 2, or R2, set to become the first humanoid robot in space. The experimental machine — looking human from the waist up — will remain boxed until after Discovery departs.

Up at the space station, meanwhile, the six-person crew welcomed a European cargo ship that was launched last week from French Guiana. The robotic spaceship docked successfully just six hours before Discovery's liftoff, keeping the shuttle countdown on track.

"Busy day in space," station commander Scott Kelly noted in a Twitter tweet.

NASA is under presidential direction to retire the shuttle fleet this summer, let private companies take over trips to orbit and focus on getting astronauts to asteroids and Mars. There's been considerable disagreement among lawmakers and the space community on how best to accomplish this.

"Godspeed Discovery," retired space shuttle program manager Wayne Hale said in a Twitter update Thursday. "Prayers for a safe flight and wisdom for decision makers."