Barry Mauk, Nicola Fox, David Sibeck, Shrikanth Kanekal, Joseph Grebowsky, Ramona Kessel

1. Untangling complex processes within Earth’s radiation belts with the Radiation Belt Storm Probes (RBSP) mission. Barry Mauk, Nicola Fox, David Sibeck, Shrikanth Kanekal, Joseph Grebowsky, Ramona Kessel RBSP Project Science Team This document has been reviewed for ITAR restrictions and is cleared for public release

2. The RBSP Mission is designed to: • Objective: • Provide understanding, ideally to the point of predictability, of how populations of relativistic electrons and penetrating ions in space form or change in response to variable inputs of energy from the Sun. • Impacts: • Understand fundamental radiation processes operating throughout the universe. • Understand Earth’s radiation belts and related regions that pose hazards to human and robotic explorers. Intensities of Earth’s dynamic radiation belts

3. We have learned much about radiation belt physics but substantial & important mysteries remain

4. Two types of RBSP Goals • Better understand individual transport and energization mechanisms • Understand the extent to which non-linearities modify the role that whistler mode waves play in exchanging energy with and scattering radiation belt electrons. • Untangling complex processes: Better understand how these mechanisms act together to yield the complex behaviors that are observed. • What is the relationship between processes that supply electron source populations and those that generate the Ultra Low Frequency waves that can help transport those particles?  • What is the role of substorm injections in creating or modifying the global electric fields that transport and redistribute the injected plasma populations? • How dependent is the wave activity that energizes radiation belt electrons on the global electric field that creates the conditions for wave generation?

5. Example: What is the importance of EMIC waves in the control (loss) of radiation belt particles? Courtesy: A. (Sasha) Ukhorskiy Mauk & McPherron, Phys. Fluids,1980

6. It has been proposed that increases in helium concentrations stimulates EMIC wave generation Young et al., 1981; Roux et al., Rauch et al., 1982

7. Wave modifications are so profound that mass composition cannot be confidently determined Mauk & McPherron, Phys. Fluids,1980 Mauk and McIlwain, JGR, 1993

8. Global magnetosheric structure and transport generate the conditions for EMIC wave generation Global convection likely plays a key role

9. But, we remain profoundly ignorant of the configuration and dynamic of convective fields Rowland & Wygant, 1998 Hori et al. 2005

10. Dynamic injections appear required to explain the transport needed to population the regions of EMIC generation Mauk and Meng, 1983a Kivelson et al. 1979 10

11. Understanding the importance of EMIC wave control or radiation belts requires: • Improved understanding of the microphysics of wave generate. • Improved understanding of the global electromagnetic transport processes to understand how the conditions for wave generation are created. • Untangling complex processes within Earth’s radiation belts

12. What is required to untangle complex processes? 4 Did this feature form locally or was it transported Earthward? 2 Log [Phase Space Density] (s3/km6) T1+31 hrs 0 Mysterious “peak” T1 -2 Understandable motion 300 MeV/Gauss Oxygen Lui et al., 1986 3 4 5 6 7 8 9 L (RE) • Simultaneous, multipoint sampling at various spatial scales reveals source and evolution of critical features. • High quality, integrated measurements are needed to target key processes.

13. Multiple spacecraft must target key radiation belt regions with variable spacing Sun • 2 identically-instrumented spacecraft for space/time separation. • Lapping rates (4-5 laps/year) for simultaneous observations over a range of s/c separations. • 600 km perigee to 5.8 RE geocentric apogee for full radiation belts sampling. • Orbitalcadences faster than relevant magnetic storm time scales. • 2-year mission for precession to all local time positions and interaction regions. • Low inclination (10) to access allmagnetically trapped particles • Sunward spin axis for full particle pitch angle and dawn-dusk electric field sampling. • Space weather broadcast

14. RBSP has unusually comprehensive particle and fields instrument measurement capabilities Particle Sensors PSBR/RPS ECT/REPT ECT/MagEIS RBSPICE ECT/HOPE MagEIS electrons REPT HOPE protons RPS ion composition RBSPICE Energy 1eV 1keV 1MeV 1GeV EMFISIS FGM DC Magnetic Fields & Waves Sensors EMFISIS/MAG EMFISIS/Waves EFW AC Magnetic EFW Perp 2D DC Electric EFW Par 1D EMFISIS Waves AC Electric EFW E-field Spectra ~DC 10Hz 1kHz 1MHz Frequency

15. Coordinating RBSP with other missions helps greatly to untangle processes: Example: Themis Courtesy of Sibeck & Ukhorskiy

16. RBSP resolves important & universal science questions that have practical consequences • RBSP advances NASA’s Strategic Plan and Heliospheric Science Objectives: • Fundamental science. • Determining effects of solar variability on technological systems. • Developing ability to predict extreme & dynamic space conditions. • Much has been learned about radiation belt physics but our ignorance is profound in some areas: • Text book predictions about key observations are wrong. • Radiation belt dynamics is not understood. • Untangling the interaction of complex processes is needed. • RBSP provides the needed multi-point sampling and integrated measurements to make transformational advances in understanding.

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