FACTBOX: The mission of space shuttle Atlantis

(Reuters) - The U.S. space shuttle Atlantis, which blasted off on Monday, is hauling nearly 30,000 pounds (13,610 kg) of spare parts to keep the International Space Station operational once the shuttles stop flying next year.

Following are highlights of the 11-day flight, which is the 129th in shuttle program history and the fifth and final scheduled flight of the year.

* Atlantis, which entered service in 1985 and is on its 31st flight, is carrying two cargo platforms that will be attached to the space station. The pallets hold an assortment of gear, including pumps, gyroscopes and tanks of ammonia, oxygen and nitrogen, that are too big or heavy to be transported by the Russian, European or Japanese cargo haulers that will be left to carry the load after NASA retires the shuttles.

* Three spacewalks, each lasting 6 1/2 hours, are planned during Atlantis' weeklong stay. Astronauts Mike Foreman and Robert Satcher are paired for the first outing to install a spare antenna on the station truss and other tasks. Foreman will join Randy Bresnik for second spacewalk to outfit the station with another ham radio antenna. Satcher and Bresnik will make the final spacewalk to install a new oxygen tank on the U.S. airlock and place some experiments on one of the new pallets.

* Space station flight engineer Nicole Stott, who launched into space with the last shuttle crew on August 28, will transfer over to Atlantis for a ride back to Earth. It will be the last time the shuttle is used to rotate station crew members. The United States will pay Russia about $50 million per seat to fly astronauts on Soyuz capsules.

* Also returning aboard Atlantis will be part of the station's broken water recycling system, which purifies urine and waste water into potable water. NASA hopes to make repairs and return the system to the station on its next shuttle flight in February.

(Reporting by Irene Klotz, editing by Jim Loney and Will Dunham)