Science Overview. Vassilis Angelopoulos, ELFIN PI

Transcription

1 Science Overview Vassilis Angelopoulos, ELFIN PI Science Overview-1 MPDR, 2/12/2015

2 RADIATION BELTS: DISCOVERED IN 1958, STILL MYSTERIOUS Explorer 1, 1958 Time Magazine, May 4, 1959 Science Overview-2 MPDR, 2/12/2015

3 Space Weather Not Well Understood Science Overview-3 MPDR, 2/12/2015

4 PRIMARY SCIENCE OVERVIEW The Challenge Geospace storms result in relativistic electron flux increases only half of the time unclear why. Electron fluxes result from competition of acceleration, transport and loss. The first two processes are measured well by many equatorial, high altitude NASA, NOAA and DOE missions, but not loss Primary Science Objective To advance our understanding of dominant wave-loss mechanism of relativistic killer electrons. Implementation Approach Measure, for the first time, the angle and energy distribution of precipitating electrons. Determine if these bear the characteristic signature of scattering by the dominant wave scatterer, Electromagnetic Ion Cyclotron (EMIC) waves Science Closure ELFIN will compare the measured loss rates and electron properties during storms with theoretical models of EMIC wave scattering and with other potential mechanisms. One storm per month in declining phase of solar cycle 3 mo. minimum, 6 mo. baseline mission. Science Overview-4 MPDR, 2/12/2015

5 SECONDARY SCIENCE OBJECTIVE Determine magnetospheric source location of ionospheric field aligned currents (FACs), in relation to tail boundaries (dipole region, magnetotail, tail boundary). Measure FACs with magnetometer crossings of different latitudes. Adjust mapping models by comparing pitch-angle isotropy latitudes for different energy and species (i.e., different equatorial gyro-radius and thus different equatorial field line curvature) with model; then adjust model. Science Overview-5 MPDR, 2/12/2015

6 SCIENCE OBJECTIVES Objective ID Title Objective Primary OBJ 01 Radiation Belt Loss Sources Determine whether EMIC scattering is the primary loss mechanism of radiation belt killer electrons, or if other mechanisms are also important during the course of one storm. Secondary OBJ 02 Origin of Fieldaligned Currents Determine location of FAC sources relative to plasma boundaries (dipole vs. tail; inner edge of plasma sheet vs. plasma sheet boundary) Science Overview-6 MPDR, 2/12/2015

7 SCIENCE REQUIREMENTS Primary REQ ID Requirement Rationale Parent(s) Pitch angle distributions as a function of time at fixed energy provide a signature ELFIN shall measure the storm time electron SCI 01 that can be used to determine whether 0.5 pitch angle distribution within the loss cone 4 MeV electrons are scattered by EMIC OBJ 01 waves SCI 02 SCI 06 SCI 03 Secondary SCI 04 SCI 05 ELFIN shall measure the storm time electron energy spectrum within the loss cone ELFIN shall measure the full angle/energy spectrum at every ΔL=0.5 from L=3 to L=5 (minimum) or ΔL=0.25 from L=2 to L=9 (baseline) once per orbit ELFIN shall measure the storm time ion energy spectrum within the loss cone ELFIN shall measure the perpendicular and parallel components of the storm time ion pitch angle distribution within the loss cone ELFIN shall be capable of measuring magnetic field perturbations with a frequency of at least 2 Hz Energy spectra at fixed pitch angles can be used to determine the minimum resonant energy of precipitating electrons for comparison with EMIC waves Needed to determine if EMIC scattering is a dominant loss mechanism of relativistic electrons during geomagnetic storms Observations of ions within the loss cone can be used to identify the isotropy boundary Perpendicular and parallel components of the ion pitch angle distribution provide a signature that can be used to determine the isotropy boundary Needed to measure the expected EMIC waves OBJ 01, OBJ 05 OBJ 01 OBJ 02, OBJ 03 OBJ 02, OBJ 03 OBJ 02, OBJ 04 Science Overview-7 MPDR, 2/12/2015

8 MISSION OVERVIEW /- 1hr LT: Reduced science (EMIC waves not often there) hr LT: Worst case power: science ON and low power input hr LT: Best case power: science ON and high power input. Science Overview-8 MPDR, 2/12/2015

9 BACKUPS Science Overview-9 MPDR, 2/12/2015

10 SCIENCE TO MISSION FLOWDOWN ELFIN Implementation Strategy Polar orbit (>70 ), on any initial MLT (except sun-synchronous at ±1hr from noon-midnight) Full angular distribution of electrons (100keV-4MeV) measured by EPD instrument Spin-axis ~ orbit- (for stability) and B-field- (allows full pitch angle coverage by EPD) Magnetic torque coils adjust spin-axis attitude EMIC waves and B field measured by FGM instrument ELFIN Operations and Data Use Two Earth Stations (UCLA, WPI) Experimental on Amateur bands for communication Latency: < 1day including L0-L2 processing. Get >1 auroral/rad.belt crossing per 4 orbits (6 hrs). Record on-board multiple crossings, survey and select the ones to downlink later Open data policy, common data tools (SPEDAS) Complements many other missions Scientific: VAP and THEMIS (HEO) [NASA]; ERG (HEO) [JAXA]; DSX (MEO), VPM (LEO) [DOD]; ACE, WIND, DSCOVR (L1) Operational: DMSP (LEO), GPS (MEO) [DOD]; LANL (HEO) [DOE]; POES (LEO), GOES (HEO) [NOAA] Science Overview-10 MPDR, 2/12/2015