Van Allen Probes (RBSP)

The Van Allen Probes discovered a previously unknown third radiation belt, or 'storage ring,' that appeared in September 2012 and persisted for about a month before dissipating. Prior to this discovery, only two Van Allen radiation belts were known to exist since their discovery by James Van Allen in 1958. The probes also revealed unexpected particle acceleration processes within the belts.

The twin Van Allen Probes were launched together on August 30, 2012, aboard an Atlas V rocket from Cape Canaveral Air Force Station. The mission was originally named the Radiation Belt Storm Probes (RBSP) before being renamed in honor of James Van Allen, who discovered the radiation belts in 1958 during the Explorer 1 mission.

Two identical spacecraft allowed scientists to distinguish between spatial and temporal variations in the radiation belts. A single probe could not determine whether changes it measured were caused by the satellite moving through different regions of the belts or by actual changes occurring over time at a given location. The dual-satellite approach enabled far more precise mapping of radiation belt dynamics.

The Van Allen Probes operated for approximately seven years before NASA commanded a controlled de-orbit of both spacecraft. Probe B (RBSP-B) was decommissioned and burned up in Earth's atmosphere in mid-2019, followed by Probe A (RBSP-A) in late 2019. The controlled disposal was designed to minimize orbital debris.