Exploring the MEO Space Particle Regime Briefing to

Exploring the MEO Space Particle Regime Briefing to the National Space Weather Program Assessment Team 6 Jan 2006 Gregory Ginet AFRL/VSBX Space Vehicles Directorate Air Force Research Laboratory For Official Use Only (FOUO); Information herein NOT Approved for Export; NOT for Public Release

Exploring MEO Why Bother? • MEO is a desirable orbit regime when trading off number of satellites, global coverage and ground resolution • MEO comprises a dynamic space radiation and plasma environment • The MEO space environment is poorly quantified Electrons >~ 1 Me. V Protons >~ 25 Me. V For Official Use Only (FOUO); Information herein NOT Approved for Export; NOT for Public Release 2

Exploring MEO Current Standard Models (AE 8 & AP 8) Example: Medium-Earth Orbit (MEO) Example: Highly Elliptic Orbit (HEO) Model Dose rates behind 0. 23’’ Al J. Fennell, SEEWG 2003 DOSE (Rads/s) (>2. 5 Me. V e ; >135 Me. V p) L (RE) HEO dose measurements show that current radiation models (AE 8 & AP 8) over estimate the dose for thinner shielding For MEO orbit (L=2. 2), #years to reach 100 k. Rad: • Quiet conditions (NASA AP 8, AE 8) : 88 yrs • Active conditions (CRRES active) : 1. 1 yrs AE 8 & AP 8 under estimate the dose for 0. 23’’ shielding For Official Use Only (FOUO); Information herein NOT Approved for Export; NOT for Public Release 3

Exploring MEO from LEO? (electrons) Dosimeter data > 1. 5 Me. V electrons MEO (10000 km, 45 deg) HEO (Molnya) Qualitative signatures LEO (400 x 1600 km, 69 deg) For Official Use Only (FOUO); Information herein NOT Approved for Export; NOT for Public Release 4

Exploring MEO from LEO? (protons) Dosimeter data > 25 Me. V protons MEO (10000 km, 45 deg) HEO (Molnya) No signatures! LEO (400 x 1600 km, 69 deg) For Official Use Only (FOUO); Information herein NOT Approved for Export; NOT for Public Release 5

Exploring MEO Demonstration & Science Experiment (DSX) Wave-particle Interactions (WPIx) • 50 -m tip-to-tip antenna boom • VLF receiver & transmitter • Loss cone electron detector & magnetometer • Low-Energy Imaging Particle Spectrometer (LIPS) • High-Energy Imaging Particle 25 -m 6 -m Spectometer (HIPS) Physical Sciences, Inc. 6000 -km x 12000 -km, 28 deg MEO orbit • High Energy Proton 25 -m Spectrometer (HEPS) Space Weather Sensors (SWx) • Data for models in critical orbit regime • Determine near-field antenna environment • Compact Environmental Space Environment Testbed (NASA, AFRL) Designed for stand alone or EELV ESPA options • Measure space environmental effects on materials and electronics • Determine component system performance Anomaly Sensor (CEASE) • Low Energy Electrostatic Analyzer (LEESA) Amptek, Inc. SWx and WPIx payloads on DSX will determine MEO wave and particle distributions – critical for development of climatology, nowcast and forecast models - rated #2/44 in 2005 Do. D SERB! For Official Use Only (FOUO); Information herein NOT Approved for Export; NOT for Public Release 6

105 rads(Si)/yr 104 Quiet 103 102 DSX Orbit 1 (6000 x 12000 km, 28 deg) Quiet 101 DSX Orbit 5 (6000 x 12000, 63 deg) X 10 X 30 -80 106 rads(Si)/yr 105 From CRRESRAD model 104 Active 103 102 For Official Use Only (FOUO); Information herein NOT Approved for Export; NOT for Public Release 7

DSX SWX Sensors HIPS HEPS LIPS CEASE Sensors LEESA HIPS CEASE LCI LIPS LEESA For Official Use Only (FOUO); Information herein NOT Approved for Export; NOT for Public Release 8

Exploring MEO Wave-Particle Interactions Particles mirroring below 100 km are “lost” ELF/VLF Waves Control Particle Lifetimes Electromagnetic wave L shell = distance/RE Pitch-angle Electromagnetic waves in the Very Low Frequency (VLF) range (3 -30 k. Hz) scatter and accelerate radiation belt electrons through cyclotron resonance interactions For Official Use Only (FOUO); Information herein NOT Approved for Export; NOT for Public Release 9

DSX WPIx Motivation Diffusion coefficient along field lines Wave power in the magnetosphere Diffusion coefficients along field lines Distribution of Resonant Wave Vectors Wave-particle resonance condition Diffusion coefficients = sum over resonances Complex dependence on energy, frequency, and pitch angle Particle lifetime along field lines (approximate 1 D solution) Full 3 D global, time dependent particle distributions Xi = (L, E, ) An understanding of VLF wave power distribution & resultant wave-particle interactions is crucial for radiation belt specification & forecasting For Official Use Only (FOUO); Information herein NOT Approved for Export; NOT for Public Release 10

DSX WPIx Payload • Receiver: – Three search coil magnetometers – Two dipole antennas – Frequency range: 1 – 50 k. Hz • Transmitter: – 1 – 50 k. Hz at up to 1 k. W – 50 k. Hz – 750 k. Hz at 1 W (local electron density) • Loss Cone Detector – Pointed into the loss cone, measures 100 -500 ke. V electrons – Correlates loss cone filling with natural and/or transmitter generated events • DC Vector Magnetometer – 0 -8 Hz three-axis measurement For Official Use Only (FOUO); Information herein NOT Approved for Export; NOT for Public Release 11

Exploring MEO Summary • MEO is a desirable orbit regime but poorly quantified • DSX science goals: – Improve understanding of dynamical processes in the slot region – Develop radiation belt specification and forecast models for the MEO region – Improve understanding of VLF propagation and wave-particle interactions • DSX technology goals – Provide improved climatology models to allow spacecraft manufacturers to optimize designs – Provide data to DSX SET experiments to help evaluate radiation effects on those systems. – Validate VLF wave injection models from space and ground based platforms For Official Use Only (FOUO); Information herein NOT Approved for Export; NOT for Public Release 12

Back-up Slides For Official Use Only (FOUO); Information herein NOT Approved for Export; NOT for Public Release 13

Space Weather in MEO A Dynamic Environment Solar cycle Geomagnetic storm and proton event Solar x-rays Solar protons Solar wind velocity Electrons Protons 7. 0 1. 0 L shell (Re) 7. 0 18 months Solar wind magnetic field Geomagnetic Activity Index 1. 0 18 months Dynamic belts For radiation Official Use Only (FOUO); Information herein NOT Approved for Export; NOT for Public Release 14

Model differences depend on energy For Official Use Only (FOUO); Information herein NOT Approved for Export; NOT for Public Release 15

Space Weather in MEO DSX Coverage Pitch-angle resolution enables mapping of distributions above orbit track For Official Use Only (FOUO); Information herein NOT Approved for Export; NOT for Public Release 16

Wave-Particle Interactions Experiment Concept of Operation ~ 100 msec Transmitter Signal Time Receiver Signal Time Volts/m VLF sounding to determine farfield properties Volts/m ~ 1 sec Volts/m ~ 2 sec Stimulated particle precipitation to determine wave-particle interactions Time Counts/sec Transmitter Signal Loss Cone Particle Detector For Official Use Only (FOUO); Information herein NOT Approved for Export; NOT for Public Release Time 17