Space shuttle Discovery has launched on a mission to deliver new science equipment to the International Space Station.

Discovery blasted off from Kennedy Space Center in Florida and rose toward orbit shortly before sunrise on Monday.

Commander Alan Poindexter is leading the Discovery's crew on a 13-day mission that includes a stop at the space station. The vehicle is carrying nearly 8,000 kilograms of supplies, including a series of new science experiments to be conducted in space. Some of the experiments focus on studying how orbiting in space can affect the human body and plant growth.

Also on board is a new exercise machine, which is part of ongoing studies into the effects of long-term space flight on muscle and bone loss in astronauts.

Moments before Discovery's launch, NASA camera caught the space station passing through its orbit above Florida. NASA's George Diller said the station is easily visible from Earth because it is more than 100 meters long and 14 meters tall.

"It is a large object, getting bigger all the time," he noted. "Six permanent crew members are there today, and about to be joined by the seven crew members of Discovery to conduct science in space."

Discovery is delivering a new astronaut sleeping quarters, an ammonia tank and a gyroscope for the space station. Astronauts will conduct three space walks during the mission to install some of the equipment to the station.

NASA officials say plans to build out and expand the station are more than 90 percent complete, mainly thanks to space shuttle and its large cargo capacity. Recent shuttle missions have delivered new sleeping quarters, laboratory segments and other modules to the station.

There are only three shuttle flights remaining before the fleet is set to be retired, later this year. After that, space station partners will rely on Russian and private launch vehicles to ferry supplies to the orbiter.

ammonia: a colourless gas with a strong smell; a clear liquid containing ammonia, used as a cleaning substance 氨；氨水

gyroscope: a device consisting of a wheel that spins rapidly inside a frame and does not change position when the frame is moved. Gyroscopes are often used to keep ships and aircraft steady. 陀螺儀；回轉(zhuǎn)儀

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（來(lái)源：VOA 編輯：陳丹妮）