By Irene Klotz

CAPE CANAVERAL, Fla., July 3 (Reuters) - U.S. space shuttle Atlantis ended its cross-country flight atop a jumbo jet on Tuesday, touching down in Florida 11 days after returning from a construction mission to the International Space Station.

The shuttle landed at California's Edwards Air Force Base on June 22 due to bad weather at its home in Florida, a diversion that costs an extra $2 million.

It took three days, and three stops for refueling, to fly it back piggyback-style on a specially modified Boeing 747 to the Kennedy Space Center at Cape Canaveral.

NASA workers will now begin preparing the spaceship for its next flight in December, when it is due to ferry Europe's Columbus research laboratory module to the space station.

NASA has two more shuttle flights before then. Shuttle Endeavour is due to lift off on Aug. 7 with a new segment for the station's frame, and shuttle Discovery is targeted for launch in October, with a connecting node for the European and later the Japanese laboratories.

NASA needs to finish building the space station, a $100 billion project of 16 nations, before the shuttles are retired in 2010.

The U.S. space agency has 12 construction missions pending and two resupply flights. More than 60 percent of the planned construction work on the station, which hovers about 220 miles (354 km) above Earth, has already been carried out.

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