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Electrodynamic Tethers

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Microsoft Encarta 96. Introduction. The latest endeavor of N.A.S.A. is the Space Tether' ... Microsoft Encarta 96. Calculations ... – PowerPoint PPT presentation

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Title: Electrodynamic Tethers


1
Electrodynamic Tethers
  • A Brief Understanding Implementation

www.tethers.com
By John Missikos
2
Contents
  • Introduction
  • Uses
  • Calculation
  • Summary

Microsoft Encarta 96
3
Introduction
  • The latest endeavor of N.A.S.A. is the Space
    Tether. This, almost simplistic device, is
    extremely diverse.
  • It can cause or stop decay of a satellites orbit
    with little energy.
  • Can be used instead of propellant on small
    (micro) satellites
  • Slingshot spacecraft into orbit and beyond.
  • Or even bring in spacecraft for a landing.

www.sciencevictoria.org.au
4
  • The Space Tether is a long conductor made
    preferably from aluminum for its high strength to
    weight ratio. It is weaved so that no one impact
    by space dust or debris will destroy it.

www.tethers.com
www.tethers.com
5
  • The immediate and simplest implementation of the
    tether is to reduce the amount of space junk
    currently and soon to be in orbit of earth.

www.tethers.com
6
Uses
  • Imagine a satellite rotating the earth currently
    having a stable orbit. When it releases the
    tether the lower end (extending anywhere from 5
    to 20km) touches the ionosphere. Here charged
    particles bombard it thus charge one end. After a
    time the tether begins to conduct a current.

7
  • If the current is not opposed then through Lenses
    law an opposition force must counteract the field
    created. In this case the kinetic energy of the
    satellite is sacrificed for the energy created.
    This particular tether design is called a
    Terminator TetherTM.

www.tethers.com
8
  • On the other hand if the current is opposed then
    there is no drag force. This can be done by
    collecting energy from the sun via solar panels.
    This not only can keep the satellite in orbit
    indefinitely as well as a means of changing orbit
    with little to no power but can serve as a much
    cheaper alternative to refueling the satellite.
    This will be done with the International Space
    Station (ISS) saving over 2 Billion dollars in
    fuel not to mention the purpose launches to get
    it up there.

Microsoft Encarta 96
9
Calculations
  • By viewing the calculations you can understand
    where the forces are coming from.
  • F B I L Sin? Force on current carrying
  • wire in a magnetic field
  • I P / V Current in terms of power
  • V B V L Voltage in terms of a length
  • of conductor moving
  • through a magnetic field
  • with velocity V

10
  • In this example we will find the dragging force
    on the tether given the power running though it
    and its velocity though the ionosphere.
  • F B I L Sin? Sin? 1 since tether is
  • perpendicular to magnetic field
  • Since V B V L
  • I P / B V L
  • Substituting I into the first equation
  • F (B P L) / (B V L By cancellation
  • F P / V
  • Thus the dragging force on the tether can
    determined by the power and velocity of the
    tether though the ionosphere. Strangely enough
    the length nor the magnetic field play a part in
    the drag.

11
Summary
  • Tethers are the next big step in space
    exploration. They will make it easier for us to
    explore by providing us with remote energy not at
    the expense of material resources. This overcomes
    one of the biggest hurdles in the
    commercialization of space travel.

12
Resources
  • Microsoft, Encarta 96 Encyclopedia
  • www.tethers.com
  • www.sciencevictoria.org.au
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