According to a statement provided to NASAWatch by Elon Musk at SpaceX:
"Falcon 9 detected an anomaly on one of the nine engines and shut it down. As designed, the flight computer then recomputed a new ascent profile in realtime to reach the target orbit, which is why the burn times were a bit longer. Like Saturn V, which experienced engine loss on two flights, the Falcon 9 is designed to handle an engine flameout and still complete its mission. I believe F9 is the only rocket flying today that, like a modern airliner, is capable of completing a flight successfully even after losing an engine. There was no effect on Dragon or the Space Station resupply mission."
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