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Topics in Space Weather Lecture 14

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Title: Topics in Space Weather Lecture 14


1
Topics in Space Weather Lecture 14

Space Weather Effects On Technological Systems
Robert R. Meier School of Computational
Sciences George Mason University rmeier_at_gmu.edu CS
I 769 29 November 6 December 2005
2
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

3
Solar Radiation and Plasma Can Affect Earth
Solar radiation, magnetospheric and galactic
particles ionize and heat Earths atmosphere and
ionosphere
March 1989 Auroral Oval
Power System Events
  • 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
www.nas.edu.ssb/cover.html
Lecture 14
4
Effect of Drag on Satellite Orbits
  • Assume elliptical orbit
  • a semi-major axis
  • m satellite mass
  • M Earth mass gtgt m
  • G gravitational constant
  • Calculate change in a resulting from drag
  • Expressions derived from Keplers Laws

5
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

FD
Fg
v
2a
6
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

F rate of change of momentum, L
A
mass
v
dx
? air density in Adx A satellite front
surface area v satellite velocity
7
Drag, cont.
  • The total energy is
  • The orbital period is

8
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

Solving for da/dt substituting for FD
9
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

10
Decay of Elliptical Orbit
11
A Simple Example Decay Rate of the Solar Max
Mission (SMM) Satellite
Courtesy, J. Lean
12
Another Example Same Satellite 30 Years Apart
Emmert et al. 2004
13
Secular Trend from 27 Objects from 1966 - 2001
Emmert et al. 2004
14
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
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