Presentation on Electrodynamic tether

1. ELECTRODYNAMIC TETHER
PRESENTED BY: UNDER THE GUIDANCE OF
SAMEEM SARKAR (15BEE0011) DR. ABRAR AHMAD
ABHISHEK KUSHWAHA (15BEEE0001)
MOHAMMAD WASIUDDIN (15BEE0008)

2.  Introduction
 Principle
 Working
 Stabilization of electrodynamic tethers
 EDT application
 Advantages
 Future scope
 Conclusion
CONTENTS

3.  Satellites have a major part to play in the present
communication system.
 There are over eight thousand satellites and other
large objects in orbit around the Earth, and there are
countless smaller pieces of debris generated by
spacecraft explosions between satellites.
 One method of removing a waste satellite from orbit
would be to carry extra propellant so that the satellite
can bring itself down out of orbit.
INTRODUCTION

4.  ELECTRODYNAMIC TETHERS (EDTs) are long conducting
wires,such as one deployed from a tether satellite.
 An ELECTRODYNAMIC tether provides a
simple and reliable alternative to the
conventional rocket thrusters.
 EDTs are basically made of aluminium alloy.
 When direct current is sent through it, it
exerts a force and the tether accelerates the
spacecraft.
 By reversing the direction of current in it, the
same tether can be used to de-orbit old
satellites.
INTRODUCTION

5. INTRODUCTION

6.  The basic principle of an
electrodynamic tether is
Lorentz force
 It is the force that a
magnetic field exerts
on a current carrying
wire in a direction
perpendicular to both
the direction of current flow
and magnetic field .
PRINCIPLE

7. PRINCIPLE
 For a charged
particle
moving with velocity
V in a magnetic field
B the resultant is in
the direction of the
force F – Fleming’s
left hand rule.

8. EARTH MAGNETIC FIELD

10. WORKING
• An EDT can be used either to accelerate or
brake an orbiting spacecraft.
• When direct current is passed through the
tether, it exerts a force against the magnetic
field and the tether accelerates the spacecraft.
• The gravity gradient field will tend to orient
the tether in a vertical position.

11.  In an EDT drag system such as the
terminator Tether, the tether can be used to
reduce the orbit of the spacecraft.
 The electrons are collected at one end of the
tether and expelled at the other end.
 This current interacts with the earth’s
magnetic field and causes a force which
opposes tether.
 This decreases the orbit of the tether.

12.  The lorentz force acts on the electrons in
tether.
 A hallow cathode causes the tube to heatup
and produce xenon gas.
 Electrons interact with heat gas to
create a plasma.
 Due to this effect electrons are discharged
rapidly.

13. Electrodynmic tethers are inherently
unstable.
 The electrodynamic forces also vary and
so a pendulum motion is developed.
 Further this motion turns in to complex
librations in both the in-plane and out-of
plane direction.
TETHER STABILIZATION

14. TETHER STABILIZATION

15. Propellant less propulsion for LEO
spacecraft.
The Terminator Tether Satellite de-orbit
System.
 Electrodynamic re-boost of the
International Space Station.
 Power Generation in Low Earth Orbit.
 Space junk cleanup.
EDT APPLICATIONS

16. EDT APPLICATIONS

17. It does not require any propellant.
 Reduces the de-orbit times.
It has the potential to make space travel
significantly cheaper.
 Boosting tethers of moderate length. (5-
20 km)
 Substantially reduce the weight of the
spacecraft.
ADVANTAGE

18. FUTURE SCOPE
 Satellite Tugboat:
Another idea is for the ED tether to be
attached to an unmanned space tugboat that
would ferry satellites to higher orbits.
 Exploring the outer planets:
The most exotic use if ED tether technology
would be to propel and power spacecraft
exploring the outer planets.

19. CONCLUSION
 EDTs may provide an economical means
of electrical power in orbit.Since ED
tethers require no propellant,they could
substantially reduce the weight of the
spacecraft and provide a cost effective
method.
 Hence electro dynamic tethers play a key
role for satellite communication system.

20. REFERENCES
• Sven G. Bilen, Brian E. Gilchrist, Carlo Bonifazi, Enrico Melchioni,
“Transient response of an electrodynamic tether system in the
ionosphere:TSS-1”, IEEE Spectrum, vol.30, pp. 1519-1535, 1995.
• John D. Williams, Juan R. Sanmartin, Lauren P. Rand, “Low work function
coating for an entirely propellantless bare electrodynamic tether” ,IEEE
Transactions on Plasma Science, vol.40, pp. 1441-1445, 2012.
• Juan R. Sanmartin, Mario Charro, Enrico C. Lorenzini, Henry B. Garrett,
Claudio Bombardelli, Cristina Bramanti, “Electrodynamic tether at Jupiter-II:
Fast moon tour after capture”, IEEE Transactions on Plasma Science,
vol.37, pp. 620-626, 2009.
• L. Johnson,”The tether solution[space propulsion, electrodynamic tether]”,
IEEE Spectrum, vol.37, pp. 38-43, 2000.

21. THANK YOU