Posted: Wed, Apr 27, 2011, 7:18 AM ET (1118 GMT)
NASA started the official countdown on Tuesday afternoon for Friday's launch of the space shuttle Endeavour on its final mission. Countdown clocks started at 2 pm EDT (1800 GMT) Tuesday for the launch of Endeavour, slated for Friday at 3:47 pm EDT (1947 GMT). The six-man crew of the STS-134 mission arrived at the Kennedy Space Center on Tuesday in preparation for the launch. Shuttle officials said they were working no technical issues in advance of the launch, and forecasters called for an 80-percent chance of acceptable launch weather Friday. The STS-134 mission, the final flight of the shuttle Endeavour, will deliver the AMS-02 Alpha Magnetic Spectrometer, an astrophysical experiment, to the ISS; the crew will also perform four spacewalks to carry out maintenance on the station.
