SpaceX Rocket Explodes On Launchpad

SpaceX's Falcon 9 rocket has exploded as part of a test on a launch pad in Cape Canaveral, Florida, according to eyewitness accounts posted to Twitter. The company was scheduled to do a static test-fire of the rocket, which it previously landed safely on a ship in April - a historic move-- after it delivered supplies to the International Space Station. Witnesses reported a huge roar from the explosion that shook nearby buildings, as well as a plume of dark smoke. SpaceX did not immediately respond to MarketWatch's request for more information. It was preparing to use the rocket for an upcoming mission to launch a communications satellite.