The NASA Radiation Belt Storm Probes (RBSP) mission aims to understand how high-energy charged particles form, vary, and evolve in space environments, particularly in Earth's magnetically trapped radiation belts. Launched in August 2012, the mission consists of two spacecraft in nearly identical, highly elliptical, low-inclination orbits (1.1 × 5.8 RE, 10°), allowing for separation of spatial and temporal effects over scales from ~0.1 to 5 RE. The spacecraft carry identical instruments measuring particles, fields, and waves to address key science questions. The mission's primary objective is to understand how relativistic electrons and ions form or change in response to solar energy inputs. Three overarching science questions are: (1) What processes produce radiation belt enhancements? (2) What are the dominant mechanisms for relativistic electron loss? (3) How do ring current and geomagnetic processes affect radiation belt behavior? The mission design enables resolution of these questions through simultaneous multipoint sampling and high-quality in situ measurements. The RBSP mission will provide comprehensive data on radiation belt dynamics, including the effects of magnetic storms, substorm injections, and wave-particle interactions. The mission's design allows for access to critical regions of the radiation belts and enables the study of spatial and temporal variations. The RBSP team will use modeling and partnerships with other missions to infer details about key processes. The mission's instruments will measure particle energy and species, electric and magnetic fields, and wave characteristics. The RBSP mission is expected to observe several magnetic storms during its 2-year lifetime, providing insights into radiation belt behavior. The mission's data will help improve predictions of space weather impacts. The RBSP mission is a critical step in understanding the complex dynamics of Earth's radiation belts and their interactions with the solar wind and magnetosphere.The NASA Radiation Belt Storm Probes (RBSP) mission aims to understand how high-energy charged particles form, vary, and evolve in space environments, particularly in Earth's magnetically trapped radiation belts. Launched in August 2012, the mission consists of two spacecraft in nearly identical, highly elliptical, low-inclination orbits (1.1 × 5.8 RE, 10°), allowing for separation of spatial and temporal effects over scales from ~0.1 to 5 RE. The spacecraft carry identical instruments measuring particles, fields, and waves to address key science questions. The mission's primary objective is to understand how relativistic electrons and ions form or change in response to solar energy inputs. Three overarching science questions are: (1) What processes produce radiation belt enhancements? (2) What are the dominant mechanisms for relativistic electron loss? (3) How do ring current and geomagnetic processes affect radiation belt behavior? The mission design enables resolution of these questions through simultaneous multipoint sampling and high-quality in situ measurements. The RBSP mission will provide comprehensive data on radiation belt dynamics, including the effects of magnetic storms, substorm injections, and wave-particle interactions. The mission's design allows for access to critical regions of the radiation belts and enables the study of spatial and temporal variations. The RBSP team will use modeling and partnerships with other missions to infer details about key processes. The mission's instruments will measure particle energy and species, electric and magnetic fields, and wave characteristics. The RBSP mission is expected to observe several magnetic storms during its 2-year lifetime, providing insights into radiation belt behavior. The mission's data will help improve predictions of space weather impacts. The RBSP mission is a critical step in understanding the complex dynamics of Earth's radiation belts and their interactions with the solar wind and magnetosphere.