ELECTRODYNAMIC TETHER PDF
ABOUT ELECTRODYNAMIC TETHER, ITS STABILIZATION, ITS ADVANTAGES. In an “electrodynamic tether drag” system, such as the Terminator Tether, the tether can be used to reduce the orbit of the spacecraft to which it is attached. The motion of the long conducting wire of a tethered satellite across the geomagnetic field creates an emf of about – V/m along the length of the tether.
|Published (Last):||23 November 2010|
|PDF File Size:||19.24 Mb|
|ePub File Size:||3.73 Mb|
|Price:||Free* [*Free Regsitration Required]|
Both the “drag” and “propulsion” variants of the electrodynamic tether can in principle replace traditional propulsion systems onboard spacecraft.
Sign up using Facebook. As a result, there are a number of theories for the varying collection techniques. An Ariadna study was conducted on the eletcrodynamic of using an electrodynamic tether to explore Jupiter with microsatellites. If successful this experiment could produce a lot of electrical power.
Electrodynamic Tethers An electrodynamic tether is essentially a long conducting wire extended from a spacecraft. At the end of a satellite’s life or a rocket stage, or anything elseit is given a signal to release a long wire antenna. Bill Christensen catalogues the inventions, technology and ideas of science fiction writers at his website, Technovelgy.
Improved methods include creating an electron emitter, such as a thermionic cathodeplasma cathode, plasma contactor, or field electron emission device. Effectively, electrical energy from the Sun, in case solar arrays are used is added to the tether system and converted into kinetic movement energy, making the spacecraft go faster Fig. Typical constants for Spindt type cathodes include: You may remember from high school physics that when you move a conducting wire through a magnetic field, a voltage is induced along the wire.
An accelerating structure is typically placed in close proximity with the emitting material as in the below figure.
Electrodynamic Tethers: Getting into the Swing
In SCL electron current flow there are so many electrons emitted from the cathode that not all of them are accelerated enough by the electron gun to escape the space charge. Thrustless turning using the EDT system is possible to allow for course correction and rendezvous in interstellar space.
A current flows if there is a differential electron number at the ends, so the tether needs to be of sizeable length. In the presence of a strong electric field, the potential outside the metal will be electrodynqmic along the line AB, so that a triangular barrier is formed, through which electrons can tunnel. The below figure describes a typical EDT system in a series bias grounded gate configuration further description of the various types of configurations analyzed have been presented  with a blow-up of an infinitesimal section of bare tether.
Energy Projects – Electrodynamic Tether – NASA
The metal can be considered a potential box, filled with electrons to the Fermi level which lies below the vacuum level by several electron volts. The following figure below displays close up visual images of a Spindt emitter. There are three active electron emission technologies usually considered for EDT applications: In reverse the EDT system could be used for acceleration.
Any exposed conducting section of the EDT system can passively ‘passive’ and ‘active’ emission refers to the use of pre-stored energy in order to achieve the desired effect collect electron or ion current, depending on the electric potential of the spacecraft body with respect to the ambient plasma. By adding a battery or solar panel to the EDT circuit, the induced current is overcome, reversing the current direction; the force experienced by the tether is now in the same direction as the EDT’s motion.
This Science Fiction in the News story used with permission from Technovelgy. All of the applications mentioned in the table are elaborated upon in the Tethers Handbook.
Electrodynamic Tether / ACT / ESA
An alternative novel mission concept has been recently conceived based on conductive tethers providing both power and propulsion at Jupiter to allow a cost-effective tour of the Jovian system including tefher with the moons Io and Europa. It will add or remove energy to the orbit, thereby increasing the altitude by changing the orbit into an elliptical one. However, an uninsulated tether will be able to collect free electrons over a large part of its length instead of just at its tip.
System level configurations will be presented for each device, as well as the relative costs, electrodtnamic, and validation. They are often modeled as solid endbodies, except they are a small percentage of the solid spheres surface area. Models, accepted by scientists for more than 30 years, are incorrect and must be rewritten. In order to maximize the thrusting capability of the system a significant portion of the bare tether should be insulated.
However, since converting the orbital energy into electrical power will lower the orbit of the spacecraft there’s no such thing as a free lunchthis technique is probably only useful for providing high-power energy bursts to short-duration experiments. Much has to be learned about the interactions between the sheath structure, the geometry of the mesh, the size of the endbody, and its relation to current collection.
In addition, the geometry of the conducting body plays an important role in the size of the sheath and thus the total collection capability. The following derivation will describe the exact solution to tteher system accounting for all vector quantities involved, and then a second solution with the nominal condition where the magnetic field, the orbital velocity, and the trther orientation are all perpendicular to one another.
By using excess power generated by the ISS’s solar panels to drive current through a conducting tether, a tether reboost system electrodynnamic counteract the drag forces or even raise the station’s orbit. Steady current for onboard power results.
Other investigations will study the effects of the deployed tether and satellite on the space environment. This voltage depends directly on the magnetic field strength, the velocity, and the length of the wire. The retrieval will be conducted in two phases over a period of 18 hours. Many of these concepts overlap into other areas; however, they are elctrodynamic placed under the most appropriate heading for the purposes of this table. As a result, not all particles that are incident onto the surface of the thick sheath are collected.
Primary factors usually include high electrical conductivityand low density. If nothing were done to counteract this, the station would fall out of orbit within several months. In electrodynsmic case electrical power supplied by a set of solar arrays is used to run a current through the tether. As discussed, this method of creating electrical power has a serious side-effect, namely, that the spacecraft or satellite will experience drag.
The voltage along the tether will attract these free, negatively charged electrons at its positively charged end called electroeynamic anode. The attached tether, with fether diameter of 0. The TSS-1 first flew on STS inbut a mechanical problem allowed the electrorynamic to be tethwr only to height of feet. A 20 kilometer tether in low earth orbit LEO could produce up to 40 kilowatts of power; this is enough to run manned research facilities.
For this derivation, it is assumed that the magnetic field lines are all the same angle throughout the length of the tether, and that the tether is rigid.
A power supply is added to the tether system and used to drive current in the direction opposite opposing the motion-induced EMFthe tether can “push” against the Earth’s magnetic field to raise the spacecraft’s orbit. Version 2 is that they create a plasma by ejecting electrons around the debris and slowly slowing it down by the constant flow of electrons against it.
Environmental and orbital parameters can significantly influence the amount collected current.