2009-08-29 11:56:46  

    WASHINGTON, Aug. 29 (Xinhua) --

The U.S. space shuttle Discovery lifted off midnight Friday from the Kennedy Space Center in Florida after two delays, on a track to the International Space Station (ISS).

    NASA TV showed the shuttle blasted off at 11:59 p.m. EDT (0359 GMT, Saturday). Its twin solid rocket boosters separated just over two minutes into the flight.

    The reusable boosters falls back toward the Atlantic Ocean, where they will land under parachutes and be retrieved by recovery ships. They are equipped with cameras to record the performance of Discovery's external tank and any foam loss seen during Discovery's ascent, with the glow from their engines illuminating the shuttle during the night launch.

    The rocket engines boosting Discovery and its external tank towards orbit have also shut down as planned about eight and a half minutes into flight.

    Discovery was originally scheduled to lift off early Tuesday. However, Tuesday's launch attempt was called off by thunderstorms and a Wednesday try was postponed by a fuel valve trouble.

    The valve is inside Discovery's aft compartment. It is used for the flow of liquid hydrogen from the external fuel tank to the main engines.

    NASA resolved the fuel valve problem Friday and the weather also cooperated the planned launch.

    "It looks like third time really is the charm," launch director Pete Nickolenko told shuttle commander Rick Sturckow shortly before the liftoff. "We wish you and your team good luck and Godspeed."

    The shuttle will reach the ISS Sunday night.

    Discovery's flight will deliver supplies and equipment to the ISS. Inside the shuttle's cargo bay is the Leonardo Multi-Purpose Logistics Module (MPLM), a pressurized "moving van" that will be temporarily installed to the station. The module will deliver science and storage racks, a freezer to store research samples, a new sleeping compartment and the COLBERT treadmill.

    The 1,600-pound (726 kg) freezer, developed by the European Space Agency, will be installed in Japan's Kibo laboratory.

    The sleeping compartment is the third U.S.-built sleeping berth for the station crew, bringing the total number of bedrooms in the station to five. A sixth and final crew cabin is scheduled to arrive next year.

    NASA selected the treadmill's name after comedian and host Stephen Colbert of Comedy Central's "The Colbert Report" took interest during the ISS's Node 3 naming poll and urged his followers to post the name "Colbert," which received the most entries. The treadmill will be the second on the station.

    The treadmill will fly up in more than 100 pieces. The astronauts on the station are expected to spend about 20 hours putting the COLBERT together. COLBERT will reside first inside the Harmony module. Later, it will move into Tranquility.

    Discovery's 13-day mission will also include three space walks to replace experiments outside the European Space Agency's Columbus laboratory, and install a new ammonia storage tank and return the used one.

    Ammonia is used to move excess heat from inside the station to the radiators located outside. Discovery also will deliver a new crewmember and bring back another after almost two months aboard the space station.

    STS-128 is the 128th U.S. space shuttle flight, the 30th to the station, the 37th for Discovery and the fourth in 2009. Six flights to the station remain after STS-128 before the shuttles retire in 2010.

Editor: Mo Hong