"Close, but no cigar." That was how SpaceX founder Elon Musk described his company's first attempt at landing the Falcon 9 rocket's first stage on a barge in the middle of the ocean. To be clear, it wasn't a complete disaster: the first stage didn't disintegrate or crash into the water, but it did land too hard on the platform and (according to some reports) broke when it hit the ground. As to what exactly went wrong, Musk revealed on Twitter that the grid fins, which steered the structure onto the platform and stabilized it in the air, ran out of hydraulic fluid right as the stage was touching down. He said the flight next month is already loaded with 50 percent more hydraulic fluid, so the second landing attempt could achieve a result closer to what SpaceX wants.