Space shuttle leaves orbit for Florida landing

CAPE CANAVERAL, Fla., Sep 21 (Reuters) Astronauts aboard space shuttle Atlantis fired their ship's braking rockets today to leave orbit and head for landing after a 12-day construction mission at the International Space Station.

Flying upside-down and backward over the Indian Ocean, Atlantis began an hour-long dive back to Earth with touchdown at the Kennedy Space Center in Florida scheduled for 1551 IST.

Atlantis' descent from space began at 1444 IST with a 2-minute, 40-second rocket burn to shave about 205 mph from the ship's speed and drop it out of orbit.

As it knifes through the atmosphere on the way to Florida, temperatures outside the shuttle will reach nearly 3,000 degrees Fahrenheit (1,650 C).

The shuttle, which launched from Florida on September 9, was supposed to come home yesterday, but space debris worries and a poor weather forecast forced postponement for a day.

The Atlantis crew spent much of yesterday scanning the spacecraft with cameras and sensors, looking for heat shield damage after debris was spotted near the shuttle on Tuesday.

The inspection, which was the third of the flight, found nothing and NASA managers cleared Atlantis for the return home.

Engineers believe the debris was a spacer, a small piece of rigid plastic inadvertently left between pieces of ceramic tile on the shuttle's belly.

NASA has operated with utmost caution since shuttle Columbia disintegrated while returning to Earth on Febember 1, 2003 due to heat shield damage from launch debris that went undetected.

The seven astronauts on board were killed.

The shuttle fleet was grounded -- and space station construction halted as a result -- after the Columbia accident while the US space agency spent more than 1 billion dollars on safety upgrades.

After two shuttle flights to test shuttle modifications, NASA launched Atlantis on the first of at least 15 flights to complete the half-finished space station by 2010, when the shuttles will be retired.

The six astronauts on Atlantis completed the main task of their mission last week with the delivery and installation of a 372 million dollars solar power unit and truss structure on the station.

Their work included three long and complex spacewalks.

The 240-foot-long solar array will double the electricity on the space outpost when it is fully activated on a shuttle mission scheduled to launch in December.

Reuters SP GC1549