(CNN) -- The Space Shuttle Atlantis is scheduled to blast off from Florida on Monday afternoon, to haul key spare parts to prolong the life of the International Space Station.
Liftoff is planned for 2:28 p.m. ET at the Kennedy Space Center near Cape Canaveral.
The delivery will add years to the station's life after the space shuttle fleet is retired next year, according to NASA. Monday's launch is among six planned before then.
"You'll see this theme in some of the flights that are going to come after ours as well," said Brian Smith, the lead space station flight director for the 11-day mission. "This flight is all about spares. Basically, we're getting them up there while we still can."
Some parts are for systems that keep the station from overheating or tumbling through space, according to NASA.
"We're taking the big ones," Smith said. "And not only are they the big ones -- they're the ones deemed most critical. That's why they're going up first."
The six-member crew will return to Earth with flight engineer Nicole Stott, who launched in August.
The weather was 90 percent favorable for a launch Monday, NASA said.
The mission also will include three spacewalks and installation of two platforms to the station's backbone. The platforms will hold spare parts to sustain station operations after the shuttles are discontinued.
"As the only vehicle large enough to carry many of the big pieces of equipment into space, several of the flights are devoted to the task," NASA said.
Other items set for delivery include nitrogen and ammonia tank assemblies, a high-pressure gas tank and the station's robotic arm. The tanks help cool and pressurize the station.