Transcript ESS 261 Topics in Magnetospheric Physics Spring 2008

ESS 261 Topics in Magnetospheric Physics
Spring 2008
Forecasting Space Weather
Syllabus
March 31 Why Study Space
Weather? ®
April 7 Humans and Space Weather
®
April 9 Basics of Magnetic Storms ®
April 11 (F) CMEs ®
April 14 CIRs
April 16 Differences between
CME and CIR Storms
April 23 Space Weather Forecast
Models (Costello Geomagnetic
Activity Index, Relativistic Electron
Forecast, Wang Sheeley, Total
Electron Content model)
April 28 Space Weather Forecast
Models continued
April 30 Introduction to simulation
codes ®
May 5 Introduction to MHD
models ®
May 7 Introduction to CCMC ®
May 12 The importance of
accurate solar wind ®
May 14 ENLIL (solar wind
model) ®
May 23 (F) Magnetospheric
models ®
May 28 SEPs at Earth ®
May 30 (F) Modeling from the
Sun to the Earth
June 2 Modeling a CME
June 4 Modeling a CME at Earth
Grading
• Each student will be required to make a presentation on
a topic related to space weather. – 50%
• Each student will be required to participate in a group
attempt to use existing simulation codes to model a
space weather event.- 50%
Lecture 1
Why Study Space Weather?
Society has grown very dependent
on systems adversely affected by
space weather phenomena.
Commercial Space
Transportation
Airline Polar Flights
Microchip technology
Precision Guided Munitions
Cell phones
Atomic Clock
Satellite Operations
Carbon Dating experiments
GPS Navigation
Ozone Measurements
Aircraft Radiation Hazard
Commercial TV Relays
Communications Satellite Orientation
Spacecraft Charging
Satellite Reconnaissance & Remote
Sensing Instrument Damage
Geophysical Exploration.
Pipeline Operations
Anti-Submarine Detection
Satellite Power Arrays
Power Distribution
Long-Range Telephone Systems
Radiation Hazards to Astronauts
Interplanetary Satellite experiments
VLF Navigation Systems (OMEGA, LORAN)
Over the Horizon Radar
Solar-Terres. Research & Applic. Satellites
Research & Operations Requirements
Satellite Orbit Prediction
Solar Balloon & Rocket experiments
Ionospheric Rocket experiments
Radar
Short-wave
Radio Propagation
200
Growth of Space Weather
Customers
• U.S. power grid infrastructure
• Commercial airline industry
• Dep. of Transportation ( GPS)
• NASA human space flight activities
• Satellite launch and operations
• DoD Operations
DOE
Nuclear Reg Comm
Schlumberger
NY/PJM Grid
Ball
Loral
NESDIS/SOCC
Digital Globe
Boeing
Lockheed
Aerospace
Echostar
NASA
Space Command
ISS Astronauts
FAA
180
Sunspot Number
A few of the agencies and industries
that rely on space weather services
today:
160
140
120
100
80
60
40
20
0
1940
1950
1960
1970
Year
Sunspot Cycles
1980
1990
2000
American
United Airlines
Northwest
Continental
Cartoon of CME Hitting the Earth
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.
SCATHA (Reagan et al., 1981)
Surface Charging: SCATHA Satellite
Observations.
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.
• Plot shows count rate of 3 MeV electrons versus time. Arrows
show times when the spacecraft star tracker had anomalies.
High Energy Electrons: Deep-Dialectric Charging
1. Electrons bury themselves in the insulator
4. Electrons build up faster than they leak
off
2. Electrons slowly leak out of the insulator
5. Discharge (electrical spark) that damages
or destroys the material
3. Influx of electrons increases to levels higher than the leakage rate
Surface Damage in a C2 MOS capacitor
Space Environment Effects: Single Event Upsets
• 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.
• Additional hazards that affect spacecraft systems.
–
–
–
–
–
Variable atmospheric drag
Enhanced ionospheric ionization
Solar x-ray (SX) and Energetic Particle Events (SEPs).
Relativistic electron events (REE)
Magnetospheric particles and fields.
Background caused by Solar Energetic Particles
• Spacecraft operating below a few thousand kilometers
encounter a significant number of atmospheric
particles during each orbit.
• Any mechanism that heats the atmosphere will
produce density increases above the level heated.
– Geomagnetic storms
– Changes in solar extreme ultraviolet (EUV) radiation.
• Heating during magnetic storms
– Strong field-aligned currents and enhanced electrojets contribute to
atmospheric heating.
– Most of the heating is in the auroral zone so polar orbiting satellites
experience the greatest effects.
• Enhanced drag can cause satellites to reenter the
atmosphere.
– Enhanced drag at perigee will cause the orbit to become more
circular and increase the interval with drag.
– Even a single density increase will alter all future orbits.
Launches must be postponed during solar
particle events
• Launches for a number of rockets
must be postponed if the flux of
>50MeV protons exceeds 100 pfu.
• The proton fluxes interfere with the
guidance system.
What would satellite operators do if they had
accurate space weather forecasts?
• Instruments and/or spacecraft turned off or safed
• Maneuver planning
• Anomaly assessments
• Orbit determination accuracy
• Increased spacecraft and instrument monitoring for
health and safety during solar storms
Humans in Space
• Particle events
>30MeV are a
concern. Can lead to
cancellation of an
EVA.
• 100MeV ions
>200pfu and crew
will shut off
equipment.
Danger to aviation
HF Communication only
• High frequency (3-30MHz)
communications problems in
polar regions.
• By 2018 estimated 1.8 million
passengers between US and
China.
Danger to aviation at lower latitudes
• The FAA Wide Area
Augmentation System
(WAAS) is used to
navigation at lower
latitudes.
• WAAS uses the GPS
satellites.
WAAS altitude errors
• Ionosphere Disturbances
impact vertical error limits,
defined by the FAA’s Lateral
Navigation Vertical
Navigation (LNAV/VNAV)
specification to be no more
that 50 meters.
• Commercial aircraft unable
to use WAAS for precision
approaches. Space weather
can cause errors greater than
50 meters.
North 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.
Area affected by blackout.
Transformers destroyed by induced
currents.
Transformer
winding failure
Transformer exit lead overheating