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By Irene Klotz

CAPE CANAVERAL, Fla., Feb 29 (Reuters) - NASA managers on Friday cleared the U.S. space shuttle Endeavour for liftoff on March 11 on the first of three flights to deliver a huge Japanese research complex to the International Space Station.

Blastoff from the Kennedy Space Center in Florida was scheduled for 2:28 a.m. EDT (0628 GMT).

Barring last-minute delays, the flight would represent the quickest turn-around between shuttle missions since NASA resumed launches 2-1/2 years after the shuttle Columbia was destroyed on re-entry into the atmosphere in 2003.

The shuttle Atlantis returned from a mission to deliver Europe's Columbus research laboratory to the space station on Feb. 20.

"We landed (Atlantis) nine days ago, which is just amazing to me," said John Shannon, who took over last week as the shuttle program manager. "The team has turned around and is ready to go."

The seven-man Endeavour crew includes two of NASA's most experienced fliers, four rookies and Japan's Takao Doi, who participated in a shuttle research mission in 1997.

The shuttle is scheduled to spend two weeks at the space station to install a storage room for Japan's Kibo laboratory complex and outfit the station's Canadian-built robot arm with a mechanical hand.

The primary portion of Kibo, which is a Japanese word for "hope," is being prepared for launch in late May. The third segment, an outdoor porch for exposing experiments to space, will follow in 2009.

During Endeavour's flight, Europe's new cargo ship, the Automated Transfer Vehicle, or ATV, will be loitering about 1.2 miles (2 km) from the station, waiting for its turn to berth. The debut flight of the European Space Agency's unmanned spacecraft is scheduled for 11:28 p.m. EST on March 7 (0428 GMT March 8). It will launch from Kourou, French Guiana.

"Space is getting to be very busy," Shannon said.

Endeavour's mission will also include a test of a heat shield repair technique NASA wants to demonstrate before a servicing call to the Hubble Space Telescope in late August or early September.

Without the space station to serve as a safe haven, a shuttle crew visiting the Hubble telescope has few options if their space ship should become too damaged to safely return to Earth.

Columbia was destroyed, and its crew of seven killed, because its heat shield was damaged on liftoff.

NASA is hoping to fly six shuttle missions this year, including the Hubble flight. The U.S. space agency needs to carry out 11 remaining space station construction missions by September 2010 when the shuttles are set for retirement. (Editing by Michael Christie and Eric Beech)

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