16 March 2009 United Launch Alliance (ULA) announced that NASA had awarded ULA a contract to launch RSBP using an Atlas V 401 rocket. NASA delayed the launch as it counted down to the four-minute mark early morning on 23 August. After bad weather prevented a launch on 24 August, and a further precautionary delay to protect the rocket and satellites from Hurricane Isaac, liftoff occurred on 30 August 2012 at 4:05 AM EDT. End of mission On 12 February 2019, mission controllers began the process of ending the Van Allen Probes mission by lowering the spacecraft's perigees, which increases their atmospheric drag and results in their eventual destructive reentry into the atmosphere. This ensures that the probes reenter in a reasonable timespan, in order to pose little threat with regards to the problem of orbital debris. The probes were projected to cease operations by early 2020, or whenever they ran out of the necessary propellant to keep their solar panels pointed at the Sun. Reentry into the atmosphere is predicted to occur in 2034. Van Allen Probe B was shut down on 19 July 2019, after mission operators confirmed that it was out of propellant. Van Allen Probe A, also running low on propellant, was deactivated on 18 October 2019, putting an end to the Van Allen Probes mission after seven years in operation. Science The Van Allen radiation belts swell and shrink over time as part of a much larger space weather system driven by energy and material that erupt off the Sun's surface and fill the entire Solar System. Space weather is the source of aurora that shimmer in the night sky, but it also can disrupt satellites, cause power grid failures and disrupt GPS communications. The Van Allen Probes were built to help scientists understand this region and to better design spacecraft that can survive the rigors of outer space. The mission aimed to further scientific understanding of how populations of relativistic electrons and ions in space form or change in response to changes in solar activity and the solar wind. The mission's general scientific objectives were to: Discover which processes - singly or in combination - accelerate and transport the particles in the radiation belt, and under what conditions. Understand and quantify the loss of electrons from the radiation belts. Determine the balance between the processes that cause electron acceleration and those that cause losses.