Electrodynamic Tether

CONTENTS

· Inroduction
· Principles
· Working
· Stabilization of electrodynamic
tether
· E.D.T Application
· Advantage
· Future scope

Introduction

Hi guys, I’m introducing to you electrodynamic https://goo.gl/images/Zib2Kutethers, like you know satellites have a made role to play in the present communication system. There are over eight thounsand satellite and other large objects in orbit around the earth and there are countless smaller pieces of debris generated by spacecraft explosion between satellite. An EDTs is basically made of aluminium alloy, when direct current is sent through it, it exerts force and the tether accelerates the spacecraft. By reversing the direction of current in it, the same tether can be used de-orbit old satellite.

Principle

The basic principle of an EDT is the LORENTZ FORCE . is a force that a magnetic field exerts on a current carrying wire in a direction https://goo.gl/images/GL2mPkperpendicular to both direction of current flow and magntic field. For a charged particle movingwith velocity V in a magnetic field B .The resultant is in the direction of the force F-Fleming’s lleft hand rule.

Working

An EDT can be used either to accelerate
or brake an orbiting spacecraft .when direct current is passed throught the tether , it exerts a force against the magnetic field and the tether accelerate the spacecraft. The gravity gradient field wll tend to orient the tether in a vertical position . 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 colleted at one endof the tether and expelled at the other end .This current interact with the earths magnetic field and cause a force which opposes the tether . This decrease the orbit of the tether.In an electrodynamic propulsion , the tether can be used to boost the orbit of the spacecraft. If a power is added to the tether system and current is driven in the opposite direction, then the the tether can push against the earths magnetic field to raise the spacecraft’s orbit.

The Lorentz force acts on the electrons in tether, a hallow cathode causes the tube to heat and produce xenon gas, electrons interact with the heat gas to create a plasma, due to this effect electrons are discharged rapidly

Tether Stabilization

The second algorithm requires only periodic mesurements of the tether end mass called “End mass acceleration” feedback method, these enables EDTs to provide long term propellant less propullsion while maintainin
g tether stability and efficiency.

EDT applications

. Propellant less propulsion for LEO spacecraft.
. The Terminator Tether satellite de-orbit system.
. Electrodynamic re-boost of
international space station.
. Power generation in low earth orbit
. Space junk clean up.

Advantages

The major advantages of tethers compared to other propulsion system is it does not require any propellant and other adavantages include ;
· It is reuseable.
· Cost effective method of re-
boosting spacecraft.
· High efficiency and good
adaptability to varying plasma
conditions.
. Reduces the de-orbit times.
· Substantially reduces the weight
of the spacecraft.
· Boosting tethers of moderate
length.

Future scope

Satellite Tugboat:Another idea is for thr ED tether to be attached to an unmanned space taugboat that would ferry satellites to higher orbits.
Exploring the outter planets: The most exotic use of ED tether technology would be to propel and power spacecraft exploring the outter planets.

Conclusion

As electrodynamic tethers can provide long term propellant-less propulsion capability for orbital maneuvering and station keeping of small satellites in low earth orbit, these are preferablly compared with the existing rocket propulsion system, also EDTs may provide an economical means of electrical power in orbit.

Hence Electro dynamic tethers play a key role for satellite communication system.