 Artist's impression of the Van Allen Probes in orbit | |
| Names | Radiation Belt Storm Probes (RBSP) |
|---|---|
| Mission type | Astrophysics |
| Operator | NASA |
| COSPAR ID | 2012-046A 2012-046B |
| SATCATno. | 38752 38753 |
| Website | vanallenprobes |
| Mission duration | Planned: 2 years Final: 7 years, 1 month, 17 days |
| Spacecraft properties | |
| Manufacturer | Applied Physics Laboratory |
| Launch mass | ~1500 kg for both |
| Start of mission | |
| Launch date | 30 August 2012, 08:05 (2012-08-30UTC08:05) UTC |
| Rocket | Atlas V 401 AV-032 |
| Launch site | Cape CanaveralSLC-41 |
| Contractor | United Launch Alliance |
| End of mission | |
| Disposal | Decommissioned |
| Deactivated | Van Allen Probe A: 18 October 2019 (2019-10-19) Van Allen Probe B: 19 July 2019 |
| Orbital parameters | |
| Reference system | Geocentric |
| Regime | Highly elliptical |
| Semi-major axis | 21,887 km (13,600 mi) |
| Perigee altitude | 618 km (384 mi) |
| Apogee altitude | 30,414 km (18,898 mi) |
| Inclination | 10.2° |
| Period | 537.1 minutes |
 Large Strategic Science Missions Heliophysics Division Living With a Star program | |
TheVan Allen Probes, formerly known as theRadiation Belt Storm Probes (RBSP),[1] were tworobotic spacecraft that were used to study theVan Allen radiation belts that surround Earth.NASA conducted the Van Allen Probes mission as part of theLiving With a Star program.[2] Understanding the radiation belt environment and its variability has practical applications in the areas of spacecraft operations, spacecraft system design, mission planning and astronaut safety.[3] The probes were launched on 30 August 2012 and operated for seven years. Both spacecraft were deactivated in 2019 when they ran out of fuel. They are expected todeorbit during the 2030s.
NASA'sGoddard Space Flight Center manages the overallLiving With a Star program of which RBSP is a project, along withSolar Dynamics Observatory (SDO). The Johns Hopkins UniversityApplied Physics Laboratory (APL) was responsible for the overall implementation and instrument management for RBSP. The primary mission was scheduled to last 2 years, with expendables expected to last for 4 years. The primary mission was planned to last only 2 years because there was great concern as to whether the satellite's electronics would survive the hostile radiation environment in the radiation belts for a long period of time. When after 7 years the mission ended, it was not because of electronics failure but because of running out of fuel. This proved the resiliency of the spacecraft's electronics. The spacecraft's longevity in the radiation belts was considered a record-breaking performance for satellites in terms of radiation resiliency.[4]
The spacecraft worked in close collaboration with theBalloon Array for RBSP Relativistic Electron Losses (BARREL), which can measure particles that break out of the belts and make it all the way to Earth's atmosphere.[5][6]
The Applied Physics Laboratory managed, built, and operated the Van Allen Probes for NASA.
The probes are named afterJames Van Allen, the discoverer of the radiation belts they studied.[4]
On 16 March 2009 United Launch Alliance (ULA) announced that NASA had awarded ULA a contract to launch RSBP using anAtlas V 401 rocket.[9] 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 fromHurricane Isaac, liftoff occurred on 30 August 2012 at 4:05 AM EDT.[10]
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 eventualdestructive 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 oforbital 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.[11]
Van Allen Probe B was shut down on 19 July 2019, after mission operators confirmed that it was out of propellant.[12] 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.[13]
TheVan Allen radiation belts swell and shrink over time as part of a much largerspace weather system driven by energy and material that erupt off the Sun's surface and fill the entireSolar System. Space weather is the source ofaurora that shimmer in the night sky, but it also can disrupt satellites, cause power grid failures and disruptGPS communications. The Van Allen Probes were built to help scientists understand this region and to better designspacecraft that can survive the rigors ofouter space.[2] The mission aimed to further scientific understanding of how populations of relativistic electrons and ions in space form or change in response to changes insolar activity and thesolar wind.[2]
The mission's general scientific objectives were to:[2]
In May 2016, the research team published their initial findings, stating that thering current that encircles Earth behaves in a much different way than previously understood.[14] The ring current lies at approximately 10,000 to 60,000 kilometres (6,200 to 37,000 mi) from Earth. Electric current variations represent the dynamics of only the low-energy protons. The data indicates that there is a substantial, persistent ring current around the Earth even during non-storm times, which is carried by high-energy protons. During geomagnetic storms, the enhancement of the ring current is due to new, low-energy protons entering the near-Earth region.[14][15]
In February 2013, a third, temporary radiation belt was discovered using data gathered by the Van Allen Probes. After a few weeks, the third belt was destroyed by a burst of solar wind.[16]
The Van Allen Probes consisted of two spin-stabilized spacecraft that were launched with a single Atlas V rocket. The two probes had to operate in the harsh conditions they were studying; while other satellites have the luxury of turning off or protecting themselves in the middle of intense space weather, the Van Allen Probes had to continue to collect data. The probes were, therefore, built to withstand the constant bombardment of particles and radiation they would experience in this intense area of space.[2]
Because it was vital that the two craft make identical measurements to observe changes in the radiation belts through both space and time, each probe carried the following instruments:
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