An unmanned SpaceX cargo mission crashed back to Earth today (June 28), marking the third failure of a resupply flight to the International Space Station in the past eight months.

SpaceX's robotic Dragon capsule blasted off atop the company's two-stage Falcon 9 rocket as planned today at 10:21 a.m. EDT (1421 GMT) from Florida's Cape Canaveral Air Force Station, headed for the orbiting lab. But something went wrong about two minutes into the flight, and the rocket broke apart, raining debris out of the sky.

"There was an overpressure event in the upper stage liquid oxygen tank. Data suggests counterintuitive cause," SpaceX founder and CEO Elon Musk said via Twitter today, which is, incidentally, his 44th birthday. "That's all we can say with confidence right now. Will have more to say following a thorough fault tree analysis."