Debris from burning satellites could be affecting Earth's magnetic field

[Admin]

The growing number of satellites burning in Earth's atmosphere has concerned scientists for years. A new paper explores how the emerging shell of "conductive dust" may affect Earth's protective magnetic field.

Debris from burning satellites could be affecting Earth's magnetic field : Read more

 

[Unclear Engineer]

While this paper does raise the general question about what all those burn-up-on-re-entry satellites are doing to our atmosphere, it seems to have some very unscientific arguments in it that detract from its credibility.

First, calling aluminum a "superconductor" is not appropriate. Even in its normal metallic state on Earth, it is not a "superconductor" that has no or almost no resistance to electrical current. As extremely fine particles in the atmosphere, it is definitely not a superconductor across the atmosphere.

And comparing the mass of the dust in the atmosphere to the mass of the plasma in the radiation belts surrounding Earth is also senseless. The radiation belts are composed mainly of plasma from cosmic radiation. It is conductive because it is a plasma. And it gets shunted to Earth's poles by our geomagnetic field, where it interacts with the atmosphere and becomes neutral particles, eventually. There is no similar mechanism for neutral metallic particles in the upper atmosphere.

And, there is nothing said about how some non-magnetic material like aluminum that is not able to conduct electricity from particle to particle, could create a magnetic field in the atmosphere.

If you want to talk about potential problems, here are a couple I suggest. One she did mention. That is the possibility of effects on the ozone layer. Depleting it would become a problem. But, I did not see any quantitative mention of a depletion effect. The other is in the general effects of atmospheric metallic particles on phenomena such as lightning. If there any known effect on the frequency, intensity, or behavior of lightning? There is often lightning associated with major volcanic eruptions, so it seems a plausible question to ask. But I do not see any analysis that says satellite debris is going to be a problem through that mechanism.

 

[Bruce Perens K6BP]

I couldn't find "superconductor" or "super" or "conductor" in the PDF of the paper, just using the search function. I didn't spend a lot of time.

I would really hope an author or editor on Space.com would have enough science to delete a line like "aluminum is a superconductor". Elemental aluminum is a conductor, but in the atmosphere it is probably aluminum oxide, an electrical insulator. Aluminum corrodes very quickly if there's any oxygen around, the reason we don't see it and we generally think aluminum does not rust is because all aluminum around us is coated with a transparent layer of aluminum oxide that protects it from further corrosion. Ask any welder.

When I see stuff like this article, I wonder if it's AI produced.

 

[Bruce Perens K6BP]

All I can think of is that the paper author believes that the aluminum in the atmosphere will become a faraday cage. It won't, because it's aluminum oxide, and not capable of shielding magnetic flux in that form.

 

[Mordyn]

This study is on very shaky theoretical ground. One major issue is the author doesn't seem to understand how atmospheric conductivity works. It is dominated in the ionosphere by the mobility of heavy atmospheric ions (H+, O+, etc.) and free electrons. Adding neutral (non-ionized) metals can actually serve to impede overall conductivity, because it increases the collision frequency between the charge carriers and neutral atoms/molecules. Thus, less current can actually "flow" before being dissipated, leading to higher (not lower) resistivity there.

Further, they argue that the magnetic field outside of a conductive layer of metal fragments containing the Earth is zero. This is only possible if those fragments can carry a strong global-scale electric current. But they are not a wire or solid piece of metal as the author envisions, rather just isolated fragments that cannot transmit a current to each other without again colliding with the neutral atmosphere. In reality, any small/finite amount of electrical resistivity will allow the magnetic field to diffuse through over time, which certainly would happen here.

They also compare with mass loading from the radiation belts, which is silly, because it is well-known to be a very low density region that precipitates very little mass. The primary ionospheric mass loading sources are typically ions from the nightside plasma sheet (responsible for many auroral phenomena) and the polar cap, where solar wind ions can directly penetrate Earth's field. These number fluxes are orders of magnitude higher than the radiation belts, and should have been compared with instead.

I could go on, alas...

 

[Unclear Engineer]

For an understanding of how shielding of magnetic fields can actually occur, I found this site helpful: https://www.kjmagnetics.com/blog.asp?p=magnetic-shielding-materials
Notice that it relies on iron, nickel or cobalt, not aluminum.

 

[Mordyn]

For an understanding of how shielding of magnetic fields can actually occur, I found this site helpful: https://www.kjmagnetics.com/blog.asp?p=magnetic-shielding-materials
Notice that it relies on iron, nickel or cobalt, not aluminum.

Yes, static magnetic fields can be locally deflected by either a containing boundary of magnetizable material (e.g. iron-based alloys) or by very highly conducting material surfaces. The circumstances of the study do not meet either of these conditions (the electrical conductivity of the metal fragments surrounded by neutral atmosphere is not high enough, and even if the fragments were pure iron, there is no way their magnetic permeability could block Earth field at such low densities--especially without any physical rigidity to the layer).

As an aside, people who work in space/geo/plasma physics typically refer to magnetic field leakage through conductive elements as "magnetic diffusion". Some reading to check out, if anyone is interested: https://en.m.wikipedia.org/wiki/Magnetic_diffusion

 

[Meteoric Marmot]

I have to say that the credibility of Space.com just took a major hit for me. This article is, to put it bluntly, trash. Tereza Pultarova needs to be virtually smacked for putting out this mess.

 

[billslugg]

Tereza has a BS in Journalism, an MS in Cultural Studies and an MS from International Space University. No grounding in physics.

 

[Unclear Engineer]

https://en.wikipedia.org/wiki/International_Space_University

Are there any real experts teaching these programs? Has any alum done anything noteworthy?

 

[billslugg]

It is a legitimate university. Founded in 1987, physically located in Strasbourg, France. Has 5,000 alumni, 200 students at any one time. Offers 1 or 2 year Master's degrees.
One of the three founders, Peter Diamandis, writes an AI blog I have been getting for a year or so.

 

[Unclear Engineer]

I am used to a "university" having a campus with classrooms, student housing and faculty colocated, and providing education across the "universe" of study areas. This one sounds very limited and a bit pretentious. It adds some credibility that it is "non-profit", compared to a for-profit diploma mill. But, this paper doesn't seem like it has any substantial science knowledge behind it. So, it makes me wonder what kind of "education" its author got for her money, there.

 

[billslugg]

This does have a campus with classrooms. Has since 1993. They have a physical building with about 200 students. It is limited to space science.

I agree that the paper is not well written. It follows a pattern of poorly written articles, by authors with no other internet presence, who never populate these forums to defend their works. Very suspicious to me. Smacks of AI.

 

[Bruce Perens K6BP]

For an understanding of how shielding of magnetic fields can actually occur, I found this site helpful: https://www.kjmagnetics.com/blog.asp?p=magnetic-shielding-materials
Notice that it relies on iron, nickel or cobalt, not aluminum.

That's only applicable to solid Faraday shields, and any conductor will do, copper works fine as does elemental aluminum. But all of that is done for near-field effects on electronics, it doesn't have much to do with the atmosphere and you can't make a Faraday shield by sprinkling ferromagnetic particles in the air.

 

[Unclear Engineer]

My understanding is that copper or other non-magnetic conductors will not shield from static magnetic fields. It is not the same as a Faraday cage for electric fields. The link I posted says as much.

 

[billslugg]

Yes, non-ferrous metals do not deflect static magnetic fields. A compass can be used inside a copper Faraday shield.

Static electric fields cannot exist inside a conductor.

Any conductor shields against time varying electric or magnetic fields simply because the time varying field induces a current which dissipates as heat.

 

[Mordyn]

My understanding is that copper or other non-magnetic conductors will not shield from static magnetic fields. It is not the same as a Faraday cage for electric fields. The link I posted says as much.

The issue is the finite (non-zero) resistivity of essentially every conductor at non-cryogenic temperatures. Copper and other non-magnetic metals will actually provide an initial shielding response to a suddenly applied but otherwise constant magnetic field. The field will diffuse through it though as the electric eddy currents the magnet field induced in the metal are dissipated as heat

 

[Unclear Engineer]

Mordyn, You just seem to be intent on confusing the issue. What you describe is not a static magnetic field, it is a transient field, with the behavior after the transient has completed becoming what we have already described for static fields. Aluminum will not shield a static magnetic field. And that is only one of the several things that are wrong with this paper.

 

[Mordyn]

Mordyn, You just seem to be intent on confusing the issue. What you describe is not a static magnetic field, it is a transient field, with the behavior after the transient has completed becoming what we have already described for static fields. Aluminum will not shield a static electric field. And that is only one of the several things that are wrong with this paper.

I am aware. The point was to describe why the shielding effect fails (it is not simply that aluminum has no effect on magnetic fields), and to clarify what determines the timescale over which the field can penetrate it. The author should provide some numerical estimation of these quantities if they want people to believe the story

 

[billslugg]

"Aluminum will not shield a static electric field"
Any conductor will shield a static electric field. Such a field cannot exist inside a conductor as it would result in a current flow which would neutralize it. All electric field lines meet conductors at right angles and end at the surface of the conductor.

 

[Unclear Engineer]

"Aluminum will not shield a static electric field"
Any conductor will shield a static electric field. Such a field cannot exist inside a conductor as it would result in a current flow which would neutralize it. All electric field lines meet conductors at right angles and end at the surface of the conductor.

Bill, of course you are correct. I meant to type "magnetic" not "electric". I have edited my post to say what I meant to say. (And pledged again not to hit "send" when interrupted before rereading my posts.)

 

[Mordyn]

"Aluminum will not shield a static electric field"
Any conductor will shield a static electric field. Such a field cannot exist inside a conductor as it would result in a current flow which would neutralize it. All electric field lines meet conductors at right angles and end at the surface of the conductor.

Yep, although I think we should be careful about the interpretation of electric "shielding." A conducting shell enclosing a point charge does not actually prevent the electric field from reappearing in full to the outside world at its outer boundary (it is only zero within the conductive material of the shell).

 

[Unclear Engineer]

Mordyn, "electric" was corrected to "magnetic" already in my post. I did not post what I actually intended to post, but have now corrected it. As corrected, it is true.

Let's stop picking nits about things that are not the issue with this story.

 

[billslugg]

Mordyn makes a good point I was not aware of.

" A conducting shell enclosing a point charge does not actually prevent the electric field from reappearing in full to the outside world at its outer boundary (it is only zero within the conductive material of the shell)."

I did not know an electric field would reappear on the other side of a conductor.
Thank you, Mordyn.

 

[Unclear Engineer]

The real effect of an electric charge inside a conducting enclosure is usually that the conducting enclosure gains a counteracting electric charge from its outside environment, and thus effectively neutralizes the field outside of itself. But, if that is precluded, then the field is not contained.

The effect of a Faraday cage is not exactly the exclusion of the field, either. It is better thought of as the nulling of the effect inside by making the field the same all around the enclosure. Due to the inverse square law, the force on a charged particle inside the enclosure ends up being the same in all directions - so a net zero in the force in any particular direction.