Ionospheric and Magnetospheric Plasma (and Neutral Density) Effects

1. Solar and Space Physics and the Vision for Space Exploration Wintergreen Resort, VA 16-20 October 2005 Ionospheric and Magnetospheric Plasma (and Neutral Density) Effects David Cooke Gregory Ginet Air Force Research Laboratory Space Vehicles Directorate Hanscom AFB, MA

2. Plasma Effects Introduction We define plasma effects as the result of interactions between the natural space plasma and a particular system, e.g. communications, radar or satellite. • Radio wave reflection and refraction • Radio link scintillation • Satellite drag (a neutral density effect) • Satellite surface charging and materials degradation There can also be plasma effects due to active on-board plasma systems (but not addressed in this presentation) • Electric propulsion • Electron beams • Tethers

3. Plasma EffectsIonosphere TURBULENT PLASMA “BUBBLES” Ionosphere formed by solar EUV/UV radiation… POLAR IONOSPHERIC DISTURBANCES EQUATORIAL IONOSPHERIC DISTURBANCES MAGNETIC EQUATOR Subject to Raleigh-Taylor instability during day to night transition …and is an inhomogeneous dielectric

4. Plasma EffectsElectron Density Effects HF communications, GPS single and dual frequency, radar & geolocation accuracy

5. Plasma EffectsScintillation Degrades UHF (SATCOM) and L-Band (GPS) systems

6. Plasma EffectsComm/Nav Outage Forecast System (C/NOFS) Ionospheric Space & Ground Sensors Forecasting Algorithms & Modeling Data Exploitation Space, ground, and modeled data usage for forecasting Combination of physics-based and empirical forecasting techniques Real-time in-situ and remote sensing data • Provide scintillation nowcasts • Develop capabilities to produce short (2-3 hrs before onset), medium (4-6 hrs before onset) and long term (24-72 hrs before onset) scintillation forecasts • Improved understanding of equatorial ionosphere and scintillation triggers / inhibitors

7. Plasma EfectsC/NOFS Payload Description • GPS Receiver • C/NOFS Occultation Receiver for Ionospheric Sensing and Specification (CORISS) • Developed by Aerospace (P. Straus PI) • Measures: Remote sensing of LOS TEC RAM Plasma Sensors • Planar Langmuir Probe (PLP) • Developed by AFRL/VS (D. Hunton PI) • Measures: Ion Density, Ion Density Variations, Electron Temperature • Ion Velocity Meter (IVM) • Developed by Univ. of Texas(R. Heelis PI) • Measures: Vector Ion Velocity, Ion Density, Ion Temperature • Electric Field Instrument • Vector Electric Field Instrument (VEFI) • Developed by NASA/GSFC (R. Pfaff PI) • Measures: Vector AC and DC electric fields • Neutral Wind Meter (NWM) • Developed by Univ. of Texas(R. Heelis PI) • Measures: Vector Neutral Wind Velocity • RF Beacon • Coherent EM Radio Tomography (CERTO) • Developed by NRL (P. Bernhardt PI) • Measures: Remote sensing of RF scintillations and LOS TEC

8. Plasma EffectsEquatorial Plasma Bubble Modeling India Pacific America Atlantic Africa Problem:Equatorial plasma bubbles (EPBs) cause degradation of communication/navigation signals DMSP EPBs 1989 - 2003 2D Longitude 3D • Solution: • Derived global climatology (seasonal/longitudinal) using DMSP data; validated with ROCSAT-1 equatorial satellite • Developed working 3D model of EPB development

9. Plasma EffectsRe-entry Wake Signature GPS Blackout Sensor Blackout Comm Blackout Incident RF Antenna Plasma Reentry plasma effects on communication and navigation systems • Air ionization and heat shield ablation generates plasma sheath around vehicle • Blackout of navigation and communication links Reentry plasma is affected by a complex list of variables. • Vehicle geometry • Heat shield composition • Trajectory Understanding of the influence of mission design variables is essential for successful tradespace analysis.

10. PREDICTED ACTUAL Neutral Density EffectsSatellite Drag • Drag errors degrade capability • - Maintain catalog of all space objects • - Predict satellite positions • - Provide Collision Avoidance warnings • - Predict satellite reentries • - Optimize satellite design Thermospheric Cooling

11. Neutral Density EffectsModeling Problem: Atmospheric density variations due to geomagnetic storms degrade AFSPC satellite tracking capability Large storm-induced variations Frank Marcos, et al. High-Accuracy Satellite Drag Model (HASDM) • Empirical model IOC at NORAD 2005 • Improvement to 5% but still… • Does not meet operational requirements • Incapable of characterizing storms • No forecast capability Solution: Develop data-driven first-principles models to replace current operational empirical models for satellite orbit prediction

12. Plasma EffectsMagnetosphere Plasma sheet & ring current Aurora Outer zone electrons Inner belt protons

13. Plasma EffectsSatellites Solar Eruption Hazard Population GeV Cosmic rays Single event effects (SEE) (ions > 40 MeV) Solar energetic particles Dielectric charging (electrons > 0.2 MeV) Solar Cell Degradation Nuclear Detonation Surface charging (electrons 5-50 keV) Trapped energetic particles Charging Damage Space plasma (and electromagnetic fields) Total Dose (> 5 MeV p+, > 1 Mev e-) keV Ionospheric drivers Optical backgrounds

14. Plasma EffectsExample: Solar Array Breakdown Negotiations Under Way For Tempo 2 Settlement ___________________________________ Space News, August 4, 1997 Solar Array Solar cell failures on TEMPO 2 GEO communications satellite • New failure mode discovered moving from 40 to 100 V arrays • Charging of spacecraft leads to discharges between the arrays and the space plasma • Subsequent Kapton pyrolosis leads to self-destruction of the 100 Volt arrays • Impact on finished, unlaunched satellites currently under investigation

15. Plasma effects on materials… M. Meshishnek

16. HET main plume region Sheath HET Plasma EffectsNASCAP-2K NASA-AF Spacecraft Charging Analyzer Program – 2000 • AFRL – NASA-SEE partnership effort • Spacecraft charging and plasma interaction model • Supercedes previous NASA – AF charging codes • Non-linear finite elements with continuous electric fields • Time dependent PIC and steady state plasma algorithms for self-consistent sheaths, wakes, and plumes • Nested Cartesian grids plus local adaptive mesh • Object tool and import from 3rd party CAD tools • Version 3.0 for LEO & GEO released Jun 05 Object ToolKit and GEO charging NASCAP2K Model of STEREO EP thruster plume effects C/NOFS potential scheme

17. Plasma EffectsCharge Control Technology Charge Control System - II Goal: Develop an easy to integrate plasma emission source for charge control. Mitigate GEO charging Control active spacecraft potential Status: Prototype in lab testing. . M.W. Geis and S. Deneault 35% reduction in weight 8X longer lifetime 1/3 complexity Ion Proportional Surface Emission Cathode Goal: Passively emit electrons in proportion to ion current Surface emission cathode employs field emission at metal-dielectric-vacuum interface Plasma ions enhance the electron emission by maintaining the positive space charge in the substrate, eliminating need for gate Status: In lab development CCS-II: Xenon plasma – 8 yr @ 0.1 A; 13 Kg charged CCS-I: Xenon plasma – 1 yr @ 0.02 A; 20 Kg, 7 boxes.

18. Space Plasma EffectsDifferent Plasma Environments

19. The Lunar ElectrosphereThanks to John Freeman • The Moon is enveloped with a sheath of photoelectrons • Observations from Apollo SIDE and CPLEE instruments • Day-side: surface potential about + 10 volts due primarily to photoelectrons, N≈104/cc within 20cm of surface, few m total height (Freeman et.al., JGR, 1973) • Terminator: surface potential of order -50 volts or higher due to energetic electrons from Solar Wind (Benson et.al., 1975) • Night-side: surface potential = -100 volts or higher in the plasmasheet. (Reasoner and Burke, 1972) • Possible hazard to equipment with exposed potentials • Water vapor events.  • Observed on several occasions (Freeman et.al., 1973) • H2O+ clearly identified • Source of events remain unidentified • Dusty Plasma • Dust raised by impacts, activity, auto-levitation becomes photo-charged and suspended against weak gravity. (Stubbs et.al, 2005) • Potential contamination source

20. Plasma EffectsSummary • The space plasma environment can affect systems in many ways • Radio wave reflection and refraction • Radio link scintillation • Satellite drag (a neutral density effect) • Satellite surface charging and materials degradation • Regions of most concern for the Vision of Space Exploration: • Earth's magnetosphere and ionosphere • The solar wind

21. Backups

22. Space Environment Hazards • Direct Solar Hazards • Radio, optical and X-ray interference • Solar energetic particle degradation and clutter • Space Particle Hazards • Radiation degradation and electronics upsets • Surface and internal charging / discharging • Surface sputtering/contamination • Ionosphere/Neutral Hazards • Comm/Nav link degradation and outage • Surveillance clutter • Satellite Drag