The upper stage—surprisingly—failed
Free of the booster, the upper stage, designated S25, continued to climb. As it approached SECO, or Second Engine Cut Off, it suddenly disappeared from view. “We think we may have lost the second stage,” SpaceX engineer John Insprucker said during the SpaceX broadcast. “What we believe right now is that the Automated Flight Termination system on the second stage appears to have triggered very late in the burn as we were headed downrange out over the Gulf of Mexico.”
