Electrodynamic Braking as a method of Asteroid Deflection.

I gather you are thinking of ferromagnetic asteroids only. Useless for carbonaceous. If you are going to drag an asteroid out of the way, i presume your mag tractor is going to weigh over 10% of the mass of the asteroid? Otherwise, drawing the 2 together is going to have little time to work before it crashes onto the surface of the asteroid, returning any energy previously removed.

Land a booster on the suface, pulse the engine with the rotation so as to produce a directional force, and for a final affexct, increase the spin so that it will self-destruct into smaller, relatively harmless pieces.

With global warming, we're as likely to try herding one our way to create an orbiting dust screen to reduce the solar gain.

Rich

High Rich,

Its great that there are other folks out there showing an interest in "Asteroid Deflection."

The proposed process is not a "tractor." The makeup of the object is irrelevant, except for the ability to attache the system to the object. If the object is ferromagnetic then it could be secured magnetically.

Your suggestion of spin fractionation is quite unique. The amount of fuel mass required for any Newtonian acceleration process will approximate ΔEnergy =1/2 Δm_fuel V²_Exhaust Where m is the required fuel mass for a rocket with an exhaust velocity of V.

The purpose of Dynamic-braking is to brake the orbital velocity by converting some of the kinetic energy of the object to electrical energy through the process of electromagnetic induction where sun field provides the excitation field and the object velocity providing the "Rate of Change." Our hypothetical object is an Aten object orbiting on about the same orbital plane as the earth. This means that the velocity vector of the object intersects the solar flux at near the optimum induction angle. This process negates the need to carry reaction mass fuel to the object. Subsystems power, including auxiliary systems and magnetic attachment can be powered by the electrical energy produced through the braking process or auxilary RTGs. The effectiveness of the orbital braking will be dependent on the ability to "dissipate power" through subsystems support or any other method.

If the object makeup is suitable, it can be used as a thermal heat sink with the energy eventually being dissipated as radiated IR. The rate of radiation will be proportional to the thermal conductivity of the object, the 4th power of its absolute temperature, and the surface area of the object.

The single greatest limiting variable is the material conductivity of the induction coils. Before the potential power production (thus braking force) can be calculated the resistance of the coil windings must be determined. Systems will be available to circulate liquid nitrogen through the cores of the coils. It is assumed that on LEO assembly and testing will be available. The time frame available for technology development is about 15 years. Optimally much less.

The JAXA Muses C mission is indicative of what is possible in terms of tracking, pacing, and landing on an asteroid. This mission is by far the most technologically advanced asteroid mission to date.

To better understand what I am proposing, it might be helpful to click on the following link and then page down to the subtitle - Electro-dynamic Braking. Also, a quick scan of the last paragraph of the essay indicates the ulitmate purpose.

http://www.bestsyndication.com/?q=072407_solar-power-sailing-in-outer-space-extend-long-distance-travel.htm

Gavilan

First, applying a field coil would overcome the generative power of the magnetic field you are generating power from to run the repulsion coil. There were a pair of orbital experiments along this line, as either drag or power generators, that did show some promise. The tethered cable/satellite experiments demonstrated the generation of power through a 5 km cable, I think? The design was a single conductor, with with electron guns dissipating the accumulated electrons.

In both cases, the generation worked, but I believe that the cables fried, possibly due to the extreme voltage developed. Ah, yws, one stopped deploying with a reel jam. Possibly caused by high voltage arc.

Normally. current needs a return path to be useful. Their single conductor design required sputtering electrons into space and the accumulation by the lead satellite of free space electrons.

Try 2 insulated wires, one equipped with graphite or bismuth shielding to reduce the available flux on one cable, and even if the two bodies developed 10,000 v differential, that will be the effect on the pair. If the reduced flux would generate 100 fewer volts, then you would have a functioning system.

Back to your situation, the drag generated was very real and measurable. Powering the tethered slave from the base should result in motorization, offering some drive power.

TSS (Tethered Satellite System), I think

Rich

Here's a link to the TSS-1R pamphlet from NASA, 1992. I haven't heard of any further work on this.

http://liftoff.msfc.nasa.gov/shuttle/sts-75/tss-1r/brochure/page_cover.html

Rich

Hi Gavilan, you asked: "The solar magnetic flux at 1 au is 1e-9 Tesla. I need confirmation of this figure from some other source than Wik. "

All I could find is that the magnetic flux at Voyager 1 (~100 au) is ~10^-10 T.

Now if this is solar magnetic flux, it cannot vary with 1/r², I guess, because then the flux at 1 au must be ~ 10^-6 T, which is 3 orders too high, I think.

Jorrie

On the other hand, if Wiki is right with 0.15 T on the sun's surface, then ~10^-6 T may be the right value for 1au!

Hello Gavilan,

The polarity of the solar magnetic field flips on a regular basis. The polarity also varies depending on specific location within the solar system, and the location of a given polarity is constantly changing. The intensity of the solar magnetic flux also varies over both time and location. These variables will need to be taken into account when computing thrust vectors.

I might also point out that the intensity of a dipole field varies as 1/r³, not 1/r². Field strengths for higher-order field configurations vary as 1/rⁿ⁺² where n is the number of pole pairs. The field strength of a magnetic quadrupole (two pole pairs) for example, varies as 1/r⁴. And depending on sunspot activity and other factors, the solar magnetic field can assume the characteristics of dipole, quadrupole, or higher-order configurations at any given time. The solar system is a very dynamic place!

Yet another factor to consider when considering electrodynamic braking of asteroids is that it can be generally assumed that metallic asteroids possess a residual - and possibly strong and possibly complex - residual magnetism that itself will interact with the local solar magnetic flux. It is more than likely that the asteroid will be rotating, complicating the specific interaction.

All of these factors must be taken into account (and compensated for) when computing thrust vectors.

-e

Europium;

Thank you for taking a moment to consider the complexities of Electrodynamic Braking as a method for Asteroid Deflection.

As complex as the solar field structure may be, extrapolating induced power from an average field density would seem less problematic than solving the net force vector and impulse for nuclear explosive deflection, which at this time, is the preferred approach.

Using Electrodynamic Braking, the force vector would always be opposite the velocity vector. The variables now reduced to only the average induced power during the impulse time where the -ΔV will approximate √(2Pt/m) Where P is the dissipated power, t is the impulse time, and m is the object mass.

Europium further enlightens by stating "

I might also point out that the intensity of a dipole field varies as 1/r³, not 1/r². Field strengths for higher-order field configurations vary as 1/rⁿ⁺² where n is the number of pole pairs. The field strength of a magnetic quadrupole (two pole pairs) for example, varies as 1/r⁴. And depending on sunspot activity and other factors, the solar magnetic field can assume the characteristics of dipole, quadrupole, or higher-order configurations at any given time. The solar system is a very dynamic place!"

This leads me to ask; would the the induced power not increase directly as the exponent of that inverse function as the object moved from from aphelion (just beyond 1 AU) towards perihelion?

As complex as Solar Field structure may be, is it unreasonable to assume that an "average" value can be estimated?

In Dynamic Braking, (not to be confused with Field Reaction Propulsion) the polarity of excitation field does not affect the Lenz dynamic brake force vector, only the polarity of the circuit power.

Gavilan

Hi Jorrie,

The picture is greatly complicated by the fact that the solar magnetic flux and the solar wind are inextricably intertwined. The solar magnetic field is entrained, at least in part, by the solar wind - a plasma consisting of free electrons and ions - and cannot be assumed to have the same characteristics as, say, a dipolar field in empty space. An entrained field behaves very differently. Plasma dynamics greatly complicate the picture as everything depends on everything else, so to speak. In the complete absence of the solar wind, the field strength nearer the Sun would be much easier to compute given a known strength at some distance (say, 100 AU) and a knowledge of the field's specific polar configuration (dipole, quadrupole, etc.).

Gavilan's question about field strength presumes a much simpler - and relatively static - picture of the Solar System's magnetic configuration independent of other considerations. It's really much more complicated than that, and a simple numeric value for the field strength at 1 AU just won't suffice.

Europium:

Your expertise is greatly appreciated. It has been some time since there has been any activity here. I hope that you reply and in doing so enlighten and direct those interested to a further understanding of this specific issue.

I am quite interested in the concept of the magnetic field as being "entrained" by the solar wind.

Would you be willing to share with us this understanding?

Can you inform or speculate how this might change the relative field angle or strength of the solar field as the objects r vector changes?

Thank you for your time and interest.

Sincerely;

Gavilan