Introduction to Space Weather
Space Weather Effects
April 26, 2012
Jie Zhang
Copyright ©
CSI 662 / PHYS 660
Spring, 2012
Roadmap
•Part 1: Sun
•Part 2: Heliosphere
•Part 3: Magnetosphere
•Part 4: Ionosphere
•Part 5: Space Weather
Effects
CH12: Space Weather Effects
CSI 662 / PHYS 660
Apr. 26, 2012
CH12: Space Weather Effects
•CH12.1 Society and Economic Impact
•CH12.2 Effects on Spacecraft
•CH12.3 Effects on Human
•CH12.4 Effects on ground-based technological system
•CH12.5 Effects on communications and navigations
•CH12.6 Space Weather Prediction and Forecasting
CH12: Space Weather Effects
References and Reading Assignment:
•Chapter 13 of Deleres D. Knipp book “Understanding
Space Weather and The Physics Behind It”
2009 Space
Weather Enterprise
Forum
May 19-20, 2009
Washington, D.C.
2012 Space Weather
Enterprise Forum
June 05, 2012
National Press Club
Washington, D.C.
Is the solar
minimum over?
Nov. 19, 2009
A “gentle” solar
maximum?
April 26, 2012
CH12.1 Society and Economic
Impact
The Society Interdependence
Economy Impact
•
•
•
•
Repair damaged S/C: $50-70 M
Replace commercial S/C: $250-300 M
Cost of major power blackout: $4-10 B
Extreme storm (“1859 Carrington event”): $1-2
Trillion
CH12.2 Effects on Spacecraft
• Spacecraft Surface Charging
• Deep Dielectric Charging
• Single Event Effect (SEE)
• Single Event Upset (SEU)
• Single Event Latchup
• Spacecraft dragging
Spacecraft Surface Charging
• A variation in the electrostatic potential of a spacecraft
surface with respect to the surrounding plasma
• A resulted electronic discharging causes problems
• Spurious electronic switching
• Breakdown of thermal coating
• Solar cell degradation
• Optical sensor degradation
• Responsible for about half of all spacecraft anomalies.
Spacecraft Surface Charging
Electric charging mechanisms
1. Particle bombardment
• electron (~Kev) penetrating
~micron into a dielectric skin
and stick in  negative
charge buildup
• In a thermal plasma, electrons
move faster; more effective
than protons on charging ->
negative charge buildup
• Particularly during satellite
eclipses
Spacecraft Surface Charging
Electric charging mechanisms
2. Photoelectric effects
• Electrons escape from the surface  positive charge
buildup on the surface
Deep Dielectric Charging
• Caused by energetic (relativistic) electrons (2-10 Mev) that
penetrate deep into the surface
• Uneven electric potential between different portions of the
inside surface of satellites
• Resulting discharging can arc directly into the satellite’s
internal electrical circuits
• Resulting discharging damages the material
Probably caused attitude control problems for
GEO satellites Intelsat K, Anik E-1 and Anik E2 on 2007 Jan. 21st and 22nd following a CME
Single Event Effect (SEE)
• Caused by energetic particles and ions (>30 Mev) penetrates
spacecraft shielding and interact with the microelectronics
(integrated circuits, ICs).
• Particles cause direct ionization of silicon materials,
producing a burst of electrons
• Single Event Upset (SEU)
• flips the logic state of a single bit (bit flip)
• Rewrite the memory or reboot the system
• Single Event Latchup (SEL)
• Lead to a permanent high state
• Disable the IC
Single Event Effect (SEE)
• More SEE events in South Atlantic Anomaly Region
SAA
Single Event Effect
• Various unplanned events due to faulty commands
• Central processing unit (CPU) to halt
• Damage to memory
Engineer design:
•Error detection and correction (EDAC), additional bit
•Memory redundancy
Spacecraft Drag
• Frictional drag force by atmospheric particles acting on the
Low-Earth-Orbit (LEO) satellites
• Decrease velocity at perigee results in a decrease in apogee
height; orbit becomes more circular
• Circular orbits experience the drag at all points; faster orbit
decay
SMM orbit
decay
Spacecraft Drag
• Heating and expansion of the thermosphere during a
geomagnetic storm
• Heating and expansion of the thermosphere by EUV and X-ray
emission of strong solar flares
• Abnormally large drag results in sudden orbit changes
• Tracking of objects are lost
• Accurate pointing becomes difficult; accurate pointing is
important for satellite constellations
Tracking of thousands of space object was lost during the
March 13 and 14, 1989 geomagnetic storms. US commands
has to re-track these objects.
Satellite Disorientation
• Some attitude control systems are guided by specific star
patterns with the field of view
• SEP particle storm produces numerous flashes of light in the
optical sensor and confuses the control system
• Loss of communication by misalignment of antenna
• Loss of satellite power by misalignment of solar panels
CH12.3 Effects on Human
• When very high energy particles encounter atoms or
molecules within the human body, the collisions cause a
release of radiation (Bremstrahlung radiation).
• The radiation ionizes the surrounding materials, producing a
region of dense ionization along its track.
• Ionizing radiation can break chemical bonds in biological
molecules which result in biological injury.
• Radiation exposure results in acute, delayed, or chronic
illness, depending on the rate and the accumulative dosage
• A person may suffer loss of appetite, digestive failure, brain
damage and even death
Radiation Health Hazard
Quantify the radiation dose
Old and SI Unites of Radiation
Deposition
Old Unit
1 rad = 10 mJ/kg
SI Unit
1 Gray (Gy) = 100
rad = 1 J/kg
Equivalent dose
Rem=RBE X rad
1 Sievert (Sv) =
quality Factor
(QF) X Gray
•rad: radiation absorbed dose
•RBE: relative biological effectiveness, 1.0 (200 Kev
gamma ray, 2.0 (protons)
Radiation Health Hazard
Recommended Limits to Radiation Exposure
Exposure
Maximum Dose
(Sv)
Equivalent Dose
(rem)
Astronaut Exposure
50 mSv in one year
~5 rem in one year
Public Exposure in
the US
5 mSv in one year
~0.5 rem in one year
Occupational
Exposure
50 mSv in one year
~5 rem in one year
Early-fetus Exposure 0.5 mSv/month
~0.05 rem in one
month
Typical Chest X-ray
0.05-0.01 mSv
~0.005-0.001 rem
Natural Background
~1 mSv in one year
~0.1 rem in one year
Radiation Health Hazard
• Earth’s magnetic field produces a factor of ~ ten reduction in
total GCR exposure for LEO, e.g., International Space
Station orbit
• Unshielded interplanetary dose to the blood forming organs
(BFO) is ~ 0.6 Sv/year, exceeding the acceptable value
• Solar energetic particles pose the greatest short-term threat to
astronauts.
Radiation Health Hazard
• Thin to moderate shielding is effective in reducing the
projected equivalent dose rate.
• As shield thickness increases, shield effectiveness drops,
because of the large number of secondary particles
Radiation Health Hazard
• Space suit has a small amount of aluminum: stops 10 Mev
protons; no extra-vehicle activity during the storm time
• Spacecraft typically have several g/cm2 of aluminum
shielding.
• Storm shelters, ~20g/cm2 or 200 kg/m2 of water equivalent
material,
Radiation hazard is also a concern for airlines that fly
commercial flights routinely over the polar cap.
(Continued on May 3, 2012)
CH12.4 Effects on ground-based
technological system
Effects of GIC
Geomagnetically Induced Current (GIC)
http://en.wikipedia.org/wiki/File:GIC_generation.jpg
Effects of GIC
Geomagnetically Induced Current (GIC)
• During space weather disturbances, enhancement of
ionospheric current induces the change of geomagnetic field
• The change of geomagnetic field in turn induces a
disturbance geo-electric field
• This induced electric field drives electric currents in groundbased technological systems, .e.g, 6 V / km
• Electric currents flow through artificial conductors present
on the surface
• Extended electric power lines
• Telecommunication cables
• Extended pipelines
• Railway lines
Effects of GIC
Power System
• GIC is a quasi-direct current (DC) (variation in order of
minutes) compared with the 50/60Hz alternating current
(AC)
• GIC flowing through a transformer winding produces extra
magnetization
• A saturated transformer converts energy to heat, reducing the
energy for transmission, and in turn, reducing the voltage
• Leading to trip-outs of individual lines to the collapse of the
entire system
Transformer Failure in
March 13-14, 1989
Storm, New Jersey
Effects of GIC
Power System
On March 13, 1989, a GIC induced by a great
geomagnetic storm caused a nine-hour blackout of the
21GW Hydro Quebec power system, leaving six million
costumers without power.
Disaster could be avoided by the preventative actions
taken by power grid managers
Effects of GIC
Pipelines
• GIC causes corrosion at points where current flows from the
pipe into the surrounding soil
CH12.5 Effects on
Communication and Navigation
Radio Wave Propagation Mode
Sudden Ionospheric Disturbance
(SID)
• Associated with strong
solar flares
• Penetration of flare Xrays causes the
enhancement density in
the D and lower E regions
• Results in sharp fadeout
of long distance radio
communication on the
sunlit side of the Earth
• Short lived, ~ 1 hour
Polar Cap Absorption (PCA)
• Caused by energetic
protons from SEP events
• Particles guided by open
field lines into the polar
cap
• Increase electron density
between 55 and 90 km
• Results in communication
blackout
• PCA is a long-lived
effect, ranging from tens
of hours to several days
Communication blackout in
polar cap region
Satellite Communication
(Satcom)
• Use UHF (>300 Mhz) and SHF band to mitigate the
ionospheric effects
• Primary long-distance communication method since 1970s
• Space weather effect on SATCOM
• Scintillation in amplitude and phase
Scintillation
• Scintillation: rapid, usually random variation of the amplitude
and phase of transionospheric radiowaves
• It is due to abrupt variation in electron density along the signal
path which produce rapid signal path variation (phase) and
defocusing (amplitude)
• It is caused by instability and turbulence
• When signal fades exceed the receiver’s fade margin, the
signal is temporarily lost
Scintillation
• Most significant variations occur near the F2-peak between
225 km and 400 km
• The scintillation effects are most pronounced in the equatorial
(± 20 deg) geomagnetic latitude belt.
• The phenomena may persist for 20 minutes to 2 hours at a
location
Satellite Navigation
GNSS: (Global Navigation Satellite System)
–
–
–
–
GPS (Global Positioning System) (USA)
GLONASS (Russia)
Galileo (Europe)
Northern Star (China)
Satellite Navigation
GPS Errors due to Scintillation
Satellite Navigation
• Primary Effects on GPS and related
systems
– Time delay and phase distortions arising from
the TEC (Total Electron Content) of the
ionosphere
• 1 TECU = 1016 electrons/m2
• 1 TECU increases the path length by ~ 0.16 m
– Scintillation in amplitude and phase at high
latitudes and equatorial latitudes
Propagation Effects & TEC
Effect
Units
Formulae
Faraday Rotation
Radians
2.97 x 10-2 f -2 HL * TEC
Group-Path-Delay
Seconds
1.34 x 10-7 f -2 * TEC
Phase Advance
Radians
8.44 x 10-7 f -1 * TEC
Doppler Shift
Hz
1.34 x 10-7 f -2 * d/dt TEC
Time Delay
Dispersion
Seconds/Hz
-2.68 x 10-7 f -3 * TEC
Phase Dispersion
Radians/Hz
-8.44 x 10-7 f -2 * TEC
MKS units are employed. The TEC is in units of electrons/square meter along the ray path, f is the radio
frequency (Hz), and HL is the component of the magnetic field along the ray path (ampere-turns/meter).
Dual frequency receiver may count for the TEC variation
WASS
– WAAS (Wide Area Augmentation System)
• A network of reference stations on the ground
• Significantly increase the accuracy, ~ order of cm
• Spacecraft approaching and landing
CH12.6 Space Weather Forecasting
• Forecast Timeframes
• Nowcast: 0 -- 2 hr
• Short-term: >2 -- 36 hr
• Mid-term: > 36 -- 120 hr
• Intermediate term: 5 days – several solar rotation
• Long-range: > several solar rotation to solar cycle
Space Weather Forecasting
• Compared with the terrestrial forecasting, space weather
forecasting is still in its infancy.
• Terrestrial weather data assimilation
• Every 6 hours, measurement of about 10 different
parameters taken at 104 to 105 observing points, which are
interpolated onto more than 106 points of a threedimensional grid used by numerical prediction model
• Space weather data
• Data are sparse, one point outside the magnetosphere (L1),
only several points inside the magnetosphere
The End