WASHINGTON — The space shuttle Atlantis roared into space Monday afternoon to begin a vital 11-day delivery run to the International Space Station.

The shuttle blasted off at 2:28 p.m. EST from Launch Pad 39A at NASA's Kennedy Space Center in Cape Canaveral, Fla. The liftoff was the second-to-last planned flight for the 24-year-old orbiter — Atlantis is slated to be retired with its two sister shuttles in about a year.

"All the vehicle systems are outstanding today, the weather is near perfect," said launch director Mike Leinbach just before launch. "We wish you good luck, Godspeed, and we'll see you just after Thanksgiving," he said to the crew.

• SLIDESHOW: Space Shuttle Atlantis launch

• SLIDESHOW: Ready for takeoff — The crew prepares for lift-off

"We really appreciate all the effort that’s gone into making this launch attempt possible," responded commander Charlie Hobaugh. "We're excited to take this incredible vehicle for a ride and meet up with another incredible vehicle, the International Space Station."

Hobaugh is leading the six-member crew on the STS-129 resupply mission to ferry about 27,250 pounds worth of spare parts to the station.

"Our flight is one of the first flights that externally will provide a lot of the spare parts and the long lead type of replacement items that are required to keep [the station] healthy and running for quite some time," Hobaugh said in a preflight news conference.

Among the large parts packed onto the shuttle are spare high-pressure gas tanks, pumps, power units and battery supplies, as well as parts for the station's robotic arm. The equipment is loaded into two massive platforms due to be installed on the station's backbone-like metal truss. The delivery should help set up the orbiting laboratory to continue to run after the space shuttles stop flying.

"These are the spares that will allow us to utilize the investment that we've put in," said Mike Sarafin, the lead shuttle flight director for the mission.

Rookies no more

Flying with Hobaugh are pilot Barry "Butch" Wilmore and mission specialists Mike Foreman, Bobby Satcher, Randy Bresnik and Leland Melvin. Wilmore, Satcher and Bresnik are rookie spaceflyers.

"We don’t use the "R" word at all," Hobaugh said. "Everybody here is an astronaut. We consider them, even though they have not been in the environment yet, seasoned astronauts."

A seventh crewmember is slated to join the STS-129 crew for the ride home: NASA astronaut Nicole Stott, a space station Expedition 21 flight engineer who's been in space for about three months, plans to fill the shuttle's remaining seat for the journey back to Earth.

The astronauts expect to spend Thanksgiving in space. Bresnik, in particular, will also miss another major family event. His wife Rebecca is expected to give birth to their second child – a baby girl – while he is space, according to ABC News.

Foreman, Satcher and Bresnik plan to carry out the mission's three planned spacewalks, or extravehicular activities (EVAs).

"All of the EVAs that were doing are six or seven hours and there's a number of complicated tasks in each one of them," Satcher said.

In addition to the spacewalks, the crew plans some complex robotic work to help attach the new cargo carriers to the station and transfer the spare parts.

"All that in 11 days,” Sarafin said. "It’s a lot to package into a finite period of time; it’s a challenging mission."

Monday’s launch marked the start of NASA’s 129th shuttle mission since the fleet began flying in 1981, as well as the 31st liftoff for Atlantis.

Tweeting the shuttle

The launch also marked the first time NASA has invited Twitter followers to attend a liftoff. About 100 fans gathered in Cape Canaveral for a two-day "tweetup" to view the flight and learn more about NASA and the shuttle mission.

"I can't stop jumping up and down!" said Jan DuRaine, who travelled from Valley Springs, Calif. to view the launch. "I want to experience the sights, the noise and the vibration from the sound waves. To me, this is the experience of a lifetime."

Attendees said they relished they opportunity even as two Atlantis astronauts – Satcher and Melvin – plan to tweet about their mission from space. Satcher is posting updates as Astro_Bones and ZeroG_MD, with Leland writing under the name Astro_Flow.

"The behind-the-scenes aspect intrigues me," said Tina Cassler of Lauderdale, Minnesota. "I hope to learn a great deal and better understand all that they do at NASA."