Space shuttle leaves station early to beat storm

CAPE CANAVERAL, Florida (Reuters) - The U.S. space shuttle Endeavour departed hastily from the International Space Station on Sunday, ending a construction mission a day early in order to land before Hurricane Dean threatens its Houston control center.

The powerful storm, which early Sunday had top winds up to 145 miles per hour (230 km per hour), was heading toward Jamaica and on track to cross Mexico's Yucatan Peninsula before making landfall late Wednesday on the central Mexican coast.

If the storm shifts north and threatens the Texas coastline, NASA would evacuate the Johnson Space Center in Houston, which oversees the shuttle during flight.

To avoid setting up an emergency command outpost at the Kennedy Space Center in Florida, NASA wants to land Endeavour a day early, with touchdown in Florida planned for 12:32 p.m. EDT on Tuesday.

Backup landing sites in California and New Mexico also may be staffed on Tuesday if the Houston center is evacuated.

Endeavour set out from the $100 billion space station at 7:56 a.m. EDT.

"Have a good trip back to Earth," station commander Fyodor Yurchikhin told the Endeavour crew as the shuttle backed away.

Replied Endeavour commander Scott Kelly: "We couldn't have accomplished the joint mission without you."

Hatches between the shuttle and space station were closed on Saturday, following an abbreviated spacewalk to finish preparing the orbital complex for the arrival of new laboratory modules beginning later this year and next.

The shuttle, whose crew includes teacher-turned-astronaut Barbara Morgan, arrived at the station on August 10 for a 10-day visit.

Morgan, who originally trained as the backup to the teacher who died in the 1986 Challenger disaster, Christa McAuliffe, participated in two educational events during her flight, similar to what had been planned for McAuliffe's mission.

A third educational session was canceled due to the shuttle's early departure from the station.

NASA also canceled the shuttle's traditional fly-around the station to document the outpost's condition.

Instead the crew was to conduct a third and final inspection of their ship's heat shield to check if it sustained any new damage while in orbit.

The shuttle is returning with a small but deep cut in two heat-resistant belly tiles, which NASA decided would not pose a threat during atmospheric re-entry.

The heat shield inspections were implemented after the 2003 Columbia disaster, which was caused by falling insulation foam knocking a hole in the wing during launch. Seven astronauts died when the shuttle broke apart during its supersonic glide through the atmosphere for landing.

Endeavour's heat shield also was nicked by foam insulation falling off the shuttle's fuel tank during launch. NASA may delay future flights to make further tank modifications.

The U.S. space agency plans 11 more construction missions, and two resupply flights to the space station, and a servicing call to the Hubble Space Telescope before the shuttles are retired in 2010.