 It began tumbling and the engine shut down after only 20 seconds of operation, sending the payload into the Pacific Ocean.At liftoff, an improper disconnect of a pad umbilical also caused a loss of helium pressurization gas in the Agena's propellant tanks.A standdown was in effect in CORONA from 20 November 1959 until 4 February 1960 to allow time for intensive R&D efforts to identify and eliminate the causes of failure.