Space Shuttle Atlantis Poised for Monday Launch

WASHINGTON ? The space shuttle Atlantis is poised to soar into space Monday to ferry six astronauts and tons of spare parts to the International Space Station.

Atlantis is slated to lift off at 2:28 p.m. EST (1928 GMT) from Launch Pad 39A at NASA's Kennedy Space Center in Cape Canaveral, Fla. A pristine 90 percent chance of clear skies is predicted.

"The weather is looking very good for launch day," shuttle weather officer Kathy Winters said.

Atlantis' STS-129 mission will be an 11-day trek to the orbiting laboratory to deliver two massive platforms packed with spare parts, including pump modules, gyroscopes, a high-pressure gas tank, a latching end for the station?s robotic arm, battery equipment, a cargo transportation container, and more. In all, Atlantis will carry about 27,250 pounds (12,360 kg) worth of supplies.

"This flight is all about spares - basically, we?re getting them up there while we still can," said Brian Smith, the lead space station flight director for the mission.

The supply run is vital to pave the way for the future, when NASA plans to retire the space shuttles and their capacity to carry up large hardware to space.

"We're looking for the long-term outfitting of the station, making sure that ISS is ready for the long haul and has the longest life capability possible," said mission commander Charlie Hobaugh in a preflight news conference.

The shuttle fleet is due to retire in the next year or so and be replaced with new rockets and spacecraft, though NASA?s human spaceflight program is under review by the Obama administration.

To set up the new spare part carriers, which will be attached to the station's backbone-like truss, the crew plans complex robotic work and three spacewalks, or EVAs (extravehicular activities) in NASA parlance.

"All of the tasks in each one of the EVAs are complex, and we've just been training to keep our focus until we're back in the airlock and safe," said mission specialist Bobby Satcher, one of three crewmembers slated to perform the spacewalks. Satcher and crewmate Leland Melvin are chronicling their spaceflight online using Twitter, with Satcher writing under the name Astro_Bones and Melvin as Astro_Flow.

Atlantis' other STS-129 crewmembers include pilot Barry "Butch" Wilmore and mission specialists Mike Foreman, Randy Bresnik and Melvin. Wilmore, Satcher and Bresnik will be making their first trips to space.

"I'm looking forward to floating around in weightlessness; the ascent itself I hear is just remarkable," Wilmore said.

• Video ? The STS-129 Crew Rehearses For Shuttle Flight  
• Image Gallery - Shuttle Discovery's Midnight Launch
• SPACE.com Video Show - Inside the International Space Station 

SPACE.com is providing complete coverage of Atlantis' STS-129 mission to the International Space Station with Staff Writer Clara Moskowitz in Washington, D.C. and Managing Editor Tariq Malik in New York. Click here for shuttle mission updates and a link to NASA TV.