Slide Number 1Space Weather Effects on Satellite Lifetimes: Atmospheric DragAn Example of Atmospheric DragSlide Number 4Slide Number 5Slide Number 6Space Environment Effects: Surface ChargingSlide Number 8Slide Number 9Slide Number 10Slide Number 11Slide Number 12Slide Number 13Slide Number 14Slide Number 15Slide Number 16Faraday’s LawPower Grids and Black OutsWhat Damages Transformers?North America Electric Reliability Corporation (NERC)Trans-continental/oceanic Fiber Optic CablesPipeline CorrosionSlide Number 23What Would Satellite Operators do if they had Accurate Space Weather Forecasts?AM and HF Radio PropagationDanger to AviationSatellite CommunicationsSatellite Signal ScintillationDanger to Aviation at Lower LatitudesWAAS Altitude ErrorsWhat Causes What? (CIR Versus CME Storms)Review of CME PropertiesSlide Number 33CIR Properties Slide Number 35More on CME and CIR StormsSolar Energetic Particles Plasma Sheet Density Plasma Sheet Temperature Spacecraft PotentialRelativistic Electrons in Radiation BeltsFormation of new Radiation beltAuroraIonospheric EffectsESS 7 ESS 7 Lectures 18, 19 and 20Lectures 18, 19 and 20November 14, 17 and 19November 14, 17 and 19Technology and Space Technology and Space WeatherWeatherSpace Weather Effects on Satellite Lifetimes: Atmospheric Drag• A satellite would orbit forever if gravity was the only force acting on it.• Near the Earth (<2000km) satellites are traveling within the Earth’s atmosphere.• Collisions with the air cause them to slow down and drop to lower altitudes.• During magnetic storms the atmosphere gets heated and the density increases.An Example of Atmospheric Drag• The increased drag can cause satellites to return to Earth.• Even if they aren’t lost their orbits are changed and they may not be able to perform their functions.Oribital DebrisNumber of SatellitesSolar MaxCleaning Low Earth Orbit (LEO)• Most satellites are in LEO• Magnetic storms remove space junk but also cripple activesatellites.Inner Belt (Protons)Outer Belt Relativistic ElectronsPlasma sheet electronsMagnetic Storms Populate the Radiation BeltsGeosynchronous Orbit (6.6 RE ) Satellites• Geosynchronous orbit where a satellite orbits the Earth in 24 hours is in the radiation belts.• Over 100 satellites orbit – used for communications, weather forecasts etc.Space Environment Effects: Surface Charging• Spacecraft charging is a variation of the electrostatic potential of the spacecraft surface with respect to the surrounding plasma. The resulting discharges can:– Cause spurious electronic switching– Breakdown vehicle thermal coatings.– Degrade amplifiers and solar cells– Degrade optical sensors.• Photoionization frees electrons from the spacecraft and it develops a positive charge.– Electrons may form a negative cloud near the spacecraft.– If the entire surface was a homogeneous conductor this would not be a problem but this isn’t the case.– Differential charging of the sunlit surface with respect to the dark surface.• Electrons with energies of a few keV can penetrate the skin of the spacecraft and charge it negatively.Effects of Surface ChargingSCATHA (Reagan et al., 1981)Surface Charging: SCATHA Satellite Observations.• Following this substorm while SCATHA was in eclipse the spacecraft charged to 20kV.Space Environment Effects: Deep Dialectric Charging• Electrons with energies between 2 and 10 MeV have enough energy to get deep into satellite surfaces.• The excess charge spreads out evenly on conducting surfaces but the charge accumulates on dielectric surfaces resulting in potential differences between different parts of the satellite.• Eventually static discharges will occur. This can happen on electron circuitry.• Left plot shows count rate of 3 MeV electrons versus time. Arrows show times when the spacecraft star tracker had anomalies. Right plot shows >2MeV electrons and anomalies. Examples of Deep Dielectric Charging3. Influx of electrons increases to levels higher than the leakage rate2. Electrons slowly leak out of the insulator1. Electrons bury themselves in the insulator4. Electrons build up faster than they leak off5. Discharge (electrical spark) that damages or destroys the materialHigh Energy Electrons: Deep-Dialectric ChargingSurface Damage in a C2 MOS CapacitorSpace Environment Effects: Single Event Upsets• Single Event Upsets are bit flips in digital micro- electronic circuits.– Damage to stored data.– Damage to software.– Stop central processing unit (CPU).– Cause CPU to write over critical data tables.– Create faulty commands.• Caused by high energy ions ionizing silicon electronics.– Galactic cosmic rays.– SEPs– Radiation belts.Effects of Single Event UpsetsBackground caused by Solar Energetic ParticlesFaraday’s Law• A time variable magnetic field can induce an electric field.• A time varying magnetic field is how an electrical generator works.• Space weather events make a time varying magnetic fields.• This can induce a voltage in wires or things like wires. tBE∂∂=×∇rrPower Grids and Black Outs• A magnetic storm in 1989 caused induced current which damaged this transformer.• It caused a black out that shut off power for 6 million people for 9 hours.What Damages Transformers?• Changing ionospheric currents induce changing magnetic fields, which induce currents in long wires• Corpuscular radiation from aurora charge conductors (like long straight wires)• Variable magnetic fields exert force on electrical components in transformer.Transformer exit lead overheatingTransformer winding failureNorth America Electric Reliability Corporation (NERC)• NERC is the Federal Energy Regulatory Commissions electric reliability coordinator.• Organized into a series of regional coordinators.•Develops and enforces reliability standards.Trans-continental/oceanic Fiber Optic Cables• Fiber optics use light instead of current to carry signals. They should not be susceptible to induced currents.• However, most 1000+km long lines need relays to boost the signal strength. These need power and hence copper wires running to them.Pipeline Corrosion• A current in a pipeline enhances corrosion.• The trans-Alaska pipeline is basically a long conductor at high latitude where there are changing magnetic fields even during substorms.Launches must be postponed during solar particle events• Launches for a number of rockets must be postponed if