Living With a Star Radiation Belt Storm Probes and Associated Geospace Missions D. G. Sibeck Project Scientist NASA Goddard Space Flight Center

Geospace: Part of the Integrated LWS Plan Distributed network of spacecraft providing continuous observations of Sun-Earth system  Solar and Heliospheric Network observing the Sun & tracking disturbances from the Sun to Earth  Geospace Network uses a comprehensive set of spacecraft to diagnose the Geospace response Stereo Lag Stereo Lead Solar Probe

Radiation Belt Storm Probes Ionosphere-Thermosphere Storm Probes UV Imager: O/N 2 and Electron Density SDO observations of EUV input Original Geospace Mission Concept

The Radiation Belt Storm Probes Mission is in Phase A Formulation Radiation Belt Storm Probes – twin spacecraft in highly elliptical orbits to understand the basic principals behind relativistic particle acceleration, transport, and loss. Launch 2012 Perigee: ~630 km altitude Apogee ~5.8 Re geocentric altitude Inclination ~10° Sun pointing, spin stabilized Duration 2 years (expendables 4 years)

Physics of the radiation belts are the physics of Charge particle acceleration, transport, and loss. Radiation Belts: Our Window on Fundamental Physics

Source, loss, and transport processes Shock-associated creation and decay of radiation belts; Quantifying adiabatic and nonadiabatic processes; ”Seed" or source populations; Ring current and its effects on energetic particles; Data assimilation and specification models --> for practical applications LWS Geospace RBSP Study Objectives

Mission Approach Simultaneous two-point measurements by identical spacecraft in common orbits. with a slow separation in phase, lapping one another 4-5 times/year, Covering the full range of local times in 2 years. Apogee of ~ 5.8 Re to sample outer belt and ring current. Perigee of ~ 630 km to sample inner belt. Simultaneous two-point measurements by identical spacecraft in common orbits. with a slow separation in phase, lapping one another 4-5 times/year, Covering the full range of local times in 2 years. Apogee of ~ 5.8 Re to sample outer belt and ring current. Perigee of ~ 630 km to sample inner belt. plasmasphere outer radiation belt Precession

Radial Profiles --> Distinguish Mechanisms When closely spaced--> determine radial phase space density gradients and discriminate between proposed source/loss regions and processes. Convection Radial Diffusion Local Acceleration

Spatial Extent When widely separated --> measure spatial extent of ring current asymmetries and wave fields.

Identify Source Populations Measure ‘seed’ or source populations: Plasma sheet Substorm injected plasma Pre-existing relativistic particles Solar Energetic Particles. and accelerated populations simultaneously.

4. Selected Investigations NASA/HQ selected the following experiments: –ECT (Spence, Boston U.) Energetic Particle Composition and Thermal Plasma Suite –EMFISIS (Kletzing, U. Iowa) Electric and Magnetic Field Instrument Suite and Integrated Science –EFW (Wygant, U. Minnesota) Electric Field and Waves Instrument for the NASA RBSP Mission –RBSPICE (Lanzerotti, N.J. Inst. Technology) Radiation Belt Storm Probes Ion Composition Experiment NASA entered into a partnership agreement with the NRO, who will supply: –RPS (Groves) Relativistic Proton Spectrometer

The Radiation Belt Storm Probes: Particle Experiments

The Radiation Belt Storm Probes: Field and Wave Experiments

Three Missions of Opportunity in Competitive Phase A Study GOLD MORE BARREL Robyn Millan Dartmouth College Balloon Array for RBSP Relativistic Electron Losses Daniel Baker U. Colorado Boulder Mission of Opportunity RadBelt Experiment Richard Eastes U. Central Florida Global-scale Observations of Limb and Disk –Final reports due September 12, 2007 –Result could augment RBSP and/or IT science.