The CRS-7 resupply flight started with a picture-perfect launch under blue Florida skies. The Falcon 9 rocket was 28 miles up -- all but out of sight from the ground -- when long-range tracking cameras showed a burst of white smoke, then small pieces of debris.
There was no immediate cause for the failure. SpaceX, the company who builds and flies the Falcon 9 and its Dragon cargo capsule, will begin a joint investigation with NASA and the FAA immediately.
"Falcon 9 experienced a problem shortly before first stage shutdown. Will provide more info as soon as we review the data," company CEO Elon Musk tweeted just after the mishap.
Sunday afternoon, SpaceX COO Gywnne Shotwell said engineers were looking at the rocket's second stage as a possible point of failure, but warned that a full investigation could take a "number of months."
"We do not expect this to be a first-stage issue," she said. "We saw some pressurization issues in the second stage."
Since the space shuttles retired in 2011, NASA's goal has been to privatize transport of space station cargo and crews to commercial companies, freeing the agency to focus on other missions, such as flights to Mars.
This flight was to be SpaceX's seventh official resupply mission to the space station. The company is a leading contender for manned flights to the station in a few years, but the crewed version of the Dragon capsule has yet to fly into space.
Sunday's failure comes exactly eight months after Orbital, NASA's other contractor for the cargo flights, suffered a dramatic failure when its Antares rocket exploded seconds after liftoff from Virginia. The company's Antares rocket has yet to return to flight.
A Russian Progress cargo launch failed back in April, further complicating the resupply plans.
But the orbiting astronauts are not in any danger of running out of supplies, NASA says. They have enough on hand to last through October, plus a Russian cargo flight was already scheduled for next month, and a Japanese flight is on the docket for August.
For now, the U.S. will remain reliant solely on Russian craft to carry astronauts to the station, but NASA officials say this mishap should not impact the burgeoning commercial crew program, and they vowed to press ahead.
"It's not whether you stumble and fall," offered station program manager Michael Suffredini. "It's what you do after you stumble and fall."
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