The NASA Radiation Belt Storm Probes (RBSP) mission aims to understand how populations of high-energy charged particles are created, vary, and evolve in space environments, particularly within Earth's magnetically trapped radiation belts. The mission, scheduled for launch in August 2012, consists of two spacecraft operating in nearly identical highly elliptical, low-inclination orbits. These orbits allow for the separation of spatial and temporal effects over a wide range of scales. The RBSP mission is equipped with a suite of instruments identical on both spacecraft, designed to measure particles (electrons, ions), fields (E and B), and wave distributions (dE and dB) to address critical scientific questions. The paper outlines the high-level science objectives of the RBSP mission, provides historical context on studies of Earth and planetary radiation belts, highlights compelling scientific mysteries, and details the mission design and observation requirements. It emphasizes the need for simultaneous multipoint sampling and high-quality, integrated in situ measurements to resolve the mysteries of the radiation belts. The RBSP mission's design includes two spacecraft in nearly identical orbits, allowing for the study of various spatial and temporal scales. The instruments are capable of measuring particle distributions, electric and magnetic fields, and wave properties, enabling researchers to discriminate between time and space variations and test hypotheses about the behavior of the radiation belts.The NASA Radiation Belt Storm Probes (RBSP) mission aims to understand how populations of high-energy charged particles are created, vary, and evolve in space environments, particularly within Earth's magnetically trapped radiation belts. The mission, scheduled for launch in August 2012, consists of two spacecraft operating in nearly identical highly elliptical, low-inclination orbits. These orbits allow for the separation of spatial and temporal effects over a wide range of scales. The RBSP mission is equipped with a suite of instruments identical on both spacecraft, designed to measure particles (electrons, ions), fields (E and B), and wave distributions (dE and dB) to address critical scientific questions. The paper outlines the high-level science objectives of the RBSP mission, provides historical context on studies of Earth and planetary radiation belts, highlights compelling scientific mysteries, and details the mission design and observation requirements. It emphasizes the need for simultaneous multipoint sampling and high-quality, integrated in situ measurements to resolve the mysteries of the radiation belts. The RBSP mission's design includes two spacecraft in nearly identical orbits, allowing for the study of various spatial and temporal scales. The instruments are capable of measuring particle distributions, electric and magnetic fields, and wave properties, enabling researchers to discriminate between time and space variations and test hypotheses about the behavior of the radiation belts.