1 Weather Weather Lecture 14 Space Weather Effects On Technological Systems Robert R. Meier School of Computational Sciences George Mason University [email protected] CSI 769 29 November & 6 December 2005
Feb 02, 2016
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Topics in Space WeatherTopics in Space Weather
Lecture 14
Topics in Space WeatherTopics in Space Weather
Lecture 14
Space Weather EffectsOn Technological Systems
Robert R. Meier
School of Computational SciencesGeorge Mason University
CSI 76929 November & 6 December 2005
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Topics• Meier
– Introductory comments– Drag effects on orbiting space objects– Thermospheric density decreases due to
greenhouse gas cooing
• Goodman– Introduction to Space Weather & Technological
Systems– Telecommunication Systems and Space Weather
Vulnerabilities– Large Storms and Impacts upon Systems– Modeling and Compensation Methods used in
Practice– Prediction Systems & Services
www.nas.edu.ssb/cover.html
Solar Radiation and Solar Radiation and Plasma Can Affect EarthPlasma Can Affect Earth
spacecraft drag, collisions, loss communications & navigation aurora currents induced in power grids spacecraft detector upsets hazards to humans in space ozone depletion in major events speculated climate impacts
LASCO Detector: 1997-11-06
March 1989:Auroral Oval
Solar radiation, magnetospheric and galactic particles ionize and heat Earth’s atmosphere and ionosphere
Power System Events
Lecture 14
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Effect of Drag on Satellite Orbits
• Assume elliptical orbit a = semi-major axism= satellite massM = Earth mass >> mG = gravitational constant
• Calculate change in a resulting from drag
• Expressions derived from Kepler’s Laws
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Drag, cont.
The dynamical equation to be solved is
– 1st term on the rhs is the centripetal acceleration, Fg
– 2nd term is the drag force– The orbital speed is:
ˆ
g D D2
GMmF = ma = F +F = - r +F
r
Fg
FD
v
GM 2 1v = -
r r a2a
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Drag, cont.
• The drag force is
• CD = drag coefficient– Accounts for
• Momentum transfer on all sides
• Fluid flow around satellite
• Turbulent effects
– Is a function of speed, shape,
air composition, and aerodynamic environment
– CD = 2.2 for a spherical satellite around 200 km
2D D
1F C Aρ v
2
D
2
2D
dLF
dtdL ρA dx v
dx vdt
dL ρAv dt
F ρAv
F = rate of changeof momentum, L
= air density in AdxA = satellite front surface areav = satellite velocity
dx
A
v mass
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Drag, cont.
• The total energy is:
• The orbital period is:
21 GMm GMmE = K +U = mv - = -
2 r 2a
3
2
1
2
2πaT =
GM
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Drag, cont.
• The work done by drag is:
• The rate of change of energy due to drag is:
• The rate of change of orbital period is:
D2
dE GMm da= = F v
dt 2a dt
1 dT 3 1 da=
T dt 2 a dt
•DdW = F dr = dE
23DC Ada a
= ρ vdt GM m
Solving for da/dt &substituting for FD:
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Drag, cont.
• Eliminating da/dt from the last two equations on slide 10, and substituting in for the drag force leads to:
• The relative change in orbital period over 1 rev is:
• The rate of change of period depends on B = CDA/m (the ballistic coefficient)
• If orbital parameters and the ballistic coefficient are known, the average atmospheric density can be determined
3DC AdT 3a= ρv dt
T 2MG m
3T 3a
= B ρv dtT 2MG
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Decay of Elliptical Orbit
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A Simple Example: Decay Rate of the Solar Max Mission (SMM) Satellite
Courtesy, J. Lean
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Another Example: Same Satellite 30 Years Apart
Emmert et al. [2004]
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Secular Trend from 27 Objects from 1966 - 2001
Emmert et al. [2004]
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Secular Trend
• Density decreases consistent with theoretical predictions of greenhouse gas increases with thermospheric GCMs– Heating of troposphere– Cooling of stratosphere, mesosphere and
thermosphere
• Observation: – Emmert et al. [J. Geophys Res., 109, A02301,
2004]
• Theory: – Roble, R. G., and R. E. Dickinson [Geophys. Res.
Lett., 16, 1441– 1444, 1989]