 This time, the problem was traced to a defective rate gyro in the Agena which had gone undetected at launch.The control system caused the stage to rotate uncontrollably with the result that the propellants were pushed to the outer edge of the tanks by centrifugal force and could not drain down into the fuel feed lines properly.Unlike with Ranger 1, the Agena had not operated long enough to achieve any significant ISP and so the probe was left in an even lower orbit.