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Space Weather Research Using Galileo Radiation Monitors

This research examines the impacts of space weather on satellite systems, including increased particle radiation, satellite charging anomalies, and total satellite loss. The study aims to develop a forecasting capability to help protect satellites and support government risk assessments, satellite design, satellite operations, space insurance, and major European space industries.

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Space Weather Research Using Galileo Radiation Monitors

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  1. Space Weather Research Using the Galileo Radiation Monitors Richard Horne, Nigel Meredith, Sarah Glauert, Alex Hands, Keith Ryden and Daniel Heynderickx 1. British Antarctic Survey, Cambridge, UK 2. Surrey Space Centre, University of Surrey, UK 3. DH Consultancy, Leuven, Belgium 6thInt Colloquium on Scientific and Fundamental Aspects of GNSS/Galileo, Valencia, 26 October 2017

  2. Background • Over 1400 operational satellites • Space Weather causes disruption • Increased particle radiation • Satellite charging - anomalies • Total satellite loss • Vulnerability a concern • Growing reliance on satellites • Electric orbit raising • New technology - COTS • What would be the impacts of an extreme Space Weather event? • Assessment for UK National Risk Register Galileo - Courtesy of ESA

  3. Electron Radiation Belts • How are electrons accelerated to more than 6 MeV? • Can we explain the global variability?

  4. Science Objectives • To test the importance of electron acceleration and loss by wave-particle interactions • To determine the flux for a 1 in 100 year event • To develop a forecasting capability to help protect satellites • Science supports: • Government risk assessment • Satellite design • Satellite operations • Space insurance • Major European space industries

  5. Time Dependent Model of the Radiation Belts Glauert et al., [2014] • Wave – particle interactions play a key role in acceleration and loss • The model is to test the importance of wave-particle interactions on a global scale • WPI are included in the diffusion coefficients Pitch angle diffusion Energy diffusion Radial transport Losses

  6. Results: 30 Year Simulation • Use GOES data at GEO as outer boundary • Most intense in declining phase1993-1994, 2003-2005 • Quiet start to new cycle1998, 2009 How reliable are theresults?

  7. GIOVE-B data • Need electron data for MEO • Giove B • ~14 hour orbit - good time resolution • Passes through the radiation belts twice on every orbit • Standard Radiation Environment Monitor (SREM), [Evans et al.,2008]. • 15 channels: • TC1 channel E >2 MeV • TC3 channel E >800 keV. • Use response functions to convert model output to SREM count rates Image: ESA

  8. Compare Model and SREM – Giove B Solid line = model Dotted line = data 2010 • Outer boundary at L* = 6.0 • Wave-particle interactions improve the agreement over previous work • Needs improvement for high energies (red) • Need better wave models > 800 keV Counts (s-1) > 2 MeV | | | | | 1 Jan 1 April 1 Jul 1 Oct 1 Jan Counts (s-1) | | | | | 1 Jan 1 April 1 Jul 1 Oct 1 Jan

  9. How Reliable are the Results? • Skill Score against persistence for > 2 MeV electrons for 2010 • 1 = perfect • 0 = as good as using the average • <1 = worse than average!!! • So ~0.7 is very good, but we need to improve • Need better wave models

  10. Space Weather – Extreme Events • What is the worst case charging event? • Designers need this information • SURF is designed to measure the currents which penetrate spacecraft surfaces and cause internal charging • Consists of three aluminium collector plates mounted in a stack credit: ESA

  11. Giove A – SURF Charging Currents Sunspot number

  12. Extreme Value Analysis – Bottom Plate • Satellite charging by ~1.6 – 2.0 MeV electrons • Penetrate 2.5 mm of Al • Medium Earth Orbit is ~ 40 times higher than GEO • First calculation of the1 in 100 year event for MEO • Very important for satellite design L* is ~ distance in Earth radii

  13. Daily Averaged Current Along the Giove A Orbit • The 1 in 100 year event exceeds0.1 pAcm-2 for 2.5 mm of Al shielding • Exceeds the NASA and European (ECSS-E-ST-20-06C) design guidelines • Expect increased risk of satellite anomalies for these levels of shielding • Need to assess carefully how much radiation shielding to include for new satellites in Medium Earth Orbit – a growth area

  14. Risk Indicator for the Galileo Orbit • The Risk Indicator combines the measured radiation environment with the BAS radiation belt model and engineering effects on the system • Risk of satellite charging – and an electrostatic discharge • Risk indicator is the charging current behind 2 mm of shielding • Compare against NASA design standard • And our 1 in 100 year event level

  15. Conclusions • Data from Giove B Radiation Monitor (SREM) used to test the importance of wave-particle interactions for electron acceleration and loss • Need better wave models to explain > 2 MeV electron variations • Analysis of GioveA (SURF) data used to determine the charging current for a 1 in 100 year event for Medium Earth Orbit – Requires more than 2.5 mm of Al shielding • Results used to support the National Risk Assessment for the UK Government and the US Space Weather benchmarks • Provided to Satellite Designers and Satellite Operators across Europe • Giove A (SURF) data used in real-time to asses the risk of satellite charging above design limits • ESA Situation Awareness Programme • Request to ESA/EU – Please provide SURF/SREM data from Galileo in real-time • And please – no more Non-Disclosure Agreements to use the data for Science Rad-Sat

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