科技英语新闻:U.S. shuttle Discovery lands in Florida, concluding flying career

This is the 39th and last flight for Discovery, the first of the three surviving U.S. space shuttles to be retired this year.

There were initially five space shuttles in the fleet -- Challenger exploded shortly after liftoff in 1986 and Columbia disintegrated on its way back to Earth in 2003. Endeavour is set for its final takeoff on April 19 and a last mission for Atlantis is scheduled for June 28, though funding for Atlantis remains in question.

The sixth shuttle, Enterprise, did test flights in the atmosphere but was never flown into space. It is already on display at a museum outside Washington.

Since its flight debut in August 1984, Discovery has transported the Hubble Space Telescope, helped carry the Japanese Kibo lab to the space station, been the first shuttle to be commanded by a female astronaut and the first to rendezvous with the Russian Mir Space Station. It holds the all-time record with 39 missions, 148 million miles (238 million kilometers) of flight distance, 5,830 orbits of Earth, and 365 days spent in space.

The 30-year-old shuttle program is ending due to high operating costs. The Obama administration wants to spur private companies to get into the space taxi business, thus freeing NASA to focus on deep space exploration and new technology development.

When the U.S. space shuttle program officially ends later this year, the Russian space program's Soyuz capsule will be the only method for transporting astronauts to and from the ISS.

Cargo delivery to the station will be run by Russia, Europe and Japan, as well as two U.S. firms -- Space Exploration Technologies and Orbital Sciences Corp.