Fun and Speculation With Lunar Magnetism

Our curmudgeonly friend over at Curmudgeon’s Corner posted a link to an interesting article from Space.Com a few days ago. The article was talking about the small localized magnetic fields that exist on the moon. I had known for a while that while the Moon doesn’t have a global magnetic field, that there were several local magnetic fields in certain areas of the moon, but hadn’t really delved too far into the topic.

The interesting thing is that they seem to believe the fields come from magnetization of the kind of nano-phase iron deposits in the regolith that I had previously been mentioning, as opposed to being due to large potential nickel-iron meteor cores as I had thought. Dennis Wingo mentioned the possibility of Ni-Fe meteors surviving impacts with the moon largely intact due to the much lower median impact velocity on the moon (due to being higher up in the gravity well as I understand it). I wonder if any of the regions of high magnetic field line up with any of the charted “Mascons”. That could make for a very interesting landing site, not just scientifically, but commercially as well.

The point they mentioned about the magnetic fields being strong enough to deflect all the solar wind based particles from the area is also interesting. As I understand it, during solar flares, the energy of the particles doesn’t go up, it’s the particle flux that goes through the roof. If an area was under enough of such a magnetic umbrella that normal solar wind particle didn’t reach it, am I correct in assuming that it’d also be safe from solar flares? While that wouldn’t get rid of concerns about Galactic Cosmic radiation (since those particles are much higher energy), not having to worry about solar flares is a good start.

Which gets me wondering even further. First off, if the Moon’s weak primordial magnetic field was enough to magnetize these regions, would a much stronger magnetic field be able to magnetize them further? Or since nanophase iron particles are so prevelant in the lunar dust everywhere, could you recreate this phenomenon elsewhere? What if you found the core of a Fe-Ni meteorite. Could you induce enough of a magnetic field in it to help with the solar radiation problem? Even better, could you induce enough of a field to deal with GCR?

This is rather potentially interesting, as it would make setting up a mining camp for such a meteor impact site a lot easier. By inducing a strong local magnetic field, you’d no longer have to bury everything, and you wouldn’t have to worry about solar flares either. Mining would get a little tougher (you’d have to make most of the equipment out of weakly non-ferromagnetic materials like some stainless steels, aluminum, etc), but by making it easier to live there, you definitely lower the hurdle for exploitation.

Here’s another wild question. The NASA scientist who spoke about nanophase iron at the Return to the Moon conference a year and a half ago made it sound as though these nanophase iron deposites were assumed to be present in the regolith almost everywhere on the moon, and that the smaller the particle, the more the magnetically susceptible the stuff was. I wonder if this is true, is the magnetic field in some of those areas high enough to help keep the lunar dust down?

I really don’t have a good feel for these numbers, and this is all just wild speculation, but does anyone here have better information? Paging Paul Spudis. Or Dennis Wingo?

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Jonathan Goff

Jonathan Goff

President/CEO at Altius Space Machines
Jonathan Goff is a space technologist, inventor, and serial space entrepreneur who created the Selenian Boondocks blog. Jon was a co-founder of Masten Space Systems, and the founder and CEO of Altius Space Machines, a space robotics startup that he sold to Voyager Space in 2019. Jonathan is currently the Product Strategy Lead for the space station startup Gravitics. His family includes his wife, Tiffany, and five boys: Jarom (deceased), Jonathan, James, Peter, and Andrew. Jon has a BS in Manufacturing Engineering (1999) and an MS in Mechanical Engineering (2007) from Brigham Young University, and served an LDS proselytizing mission in Olongapo, Philippines from 2000-2002.
Jonathan Goff

About Jonathan Goff

Jonathan Goff is a space technologist, inventor, and serial space entrepreneur who created the Selenian Boondocks blog. Jon was a co-founder of Masten Space Systems, and the founder and CEO of Altius Space Machines, a space robotics startup that he sold to Voyager Space in 2019. Jonathan is currently the Product Strategy Lead for the space station startup Gravitics. His family includes his wife, Tiffany, and five boys: Jarom (deceased), Jonathan, James, Peter, and Andrew. Jon has a BS in Manufacturing Engineering (1999) and an MS in Mechanical Engineering (2007) from Brigham Young University, and served an LDS proselytizing mission in Olongapo, Philippines from 2000-2002.
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10 Responses to Fun and Speculation With Lunar Magnetism

  1. Habitat Hermit says:

    Since this, as you point out, wouldn’t help against cosmic background radiation isn’t the point moot right from the start?

    Perhaps not. I don’t know enough about the (possibly just hypothetical) electrostatic “linear dustdevil” moving with (and being caused by) the day/night divide across Luna’s surface to say if these weak magnetic fields might protect equipment from that.

    If memory serves I read about such a feature of lunar weather as a likely explanation for sudden/early equipment failure among some of the instruments left behind by the Apollo program. Not sure if it is solid fact or tentative speculation by now.

  2. adiffer says:

    When you want to magnetize something that is ferromagnetic you usually have to heat it to allow the magnetic moments to move into alignment with the field you impose from the outside. As the material freezes again you lock in the orientations and get a residual magnetic field after your external one is gone. That’s how you make a compass anyway.

    I don’t know how mobile the magnetic moments are on the ejecta. That would be the key to progress. If the mascons are Ni-Fe cores, though, I’m sure they aren’t magnetically mobile. You’d need a lot of heat. 8)

    There is another thing to think about regarding magnetic shielding. When the flux gets high enough, the incoming plasma will push the magnetic field around. That gives you an upper limit on how much a certain field strength and arrangement can shield you. Remember also that the flux is funneled up and down through a magnetic pole and that is the opposite of a shield. Push hard enough on a weak field and you break it into a set of smaller ones with new, mobile poles. Fun.

  3. Anonymous says:

    The particles in ordinary solar wind have energies in the KeV. The dangerous high energy particles from flares have energies in the hundreds of MeV or higher, and galactic cosmic rays can be even more energetic. I doubt the relatively weak fields on the moon will provide much protection.

  4. Anonymous says:

    Jon

    Think Reiner Gamma. It has one of the strongest magnetic anomalies on the lunar surface and is not associated with any antipodal impacts. There is very little chance that this is nanophase iron.

    If you were going to do an equatorial site that is one place. Paul Spudis points out that the Apollo 16 mission landed near another big anomaly.

    Dennis

  5. Jon Goff says:

    Dennis,
    Does Reiner Gamma have a correlated mascon perchance? Do you think there’s a decent chance that there may be an intact meteorite core there? Is there any way short of boots on the ground that we could get better answers to that question?

    ~Jon

  6. Anonymous says:

    Jon

    Simple answer.

    High power radar would do it.

    High power radar with a few different frequencies would map the mascons and find the Ni-Fe surviving impactors, if any.

    Dennis

  7. Jon Goff says:

    Dennis,
    High power radar would do it.

    How high of radar are we talking about? Are any of the planned RLEP missions going to have high enough power? Or is that something else we’ll have to do ourselves?

    ~Jon

  8. Anonymous says:

    Jon

    Simple answer:

    No

    Elaboration

    There is no “scientific” requirement for a radar powerful enough to do the radar imaging needed to positively identify these objects. However, that being said, some in the community who support my hypothesis are working the issue within the context of the existing experiments.

    Another path would be a high resolution infrared imager. This imager would look in the 2-5 micron band for the thermal radiation from a NiFe object laying on the surface not covered in a lot of regolith. This would be done on the dark side of the lunar terminator right after sunset, when the much higher emissivity of the metallic objects would be detectable from orbit.

    This would constitute a second independent measure of these objects, but only for ones laying on the surface. The radar would do much better for those deeper underground (underregolith?).

    Spirit and Opportunity rovers have found NiFe objects on the surface. Now Harrison Schmidt will say that this is because of the Martian atmosphere. This simply reveals a lack of understanding of impact dynamics. The velocity of the incoming object on Mars is not significantly slowed by the atmosphere.

  9. Jon Goff says:

    Dennis,
    How high of power would you need? Are there comparable penetrating radars used in terrestrial applications? Is this something that could be done say powered by the solar panels on one of your SEP tugs (if you can get the money to implement those)?

    Just curious. Having indirect ways of checking your primary analysis are great, but it’d be nice to have that primary source of data.

    ~Jon

  10. Anonymous says:

    Jon

    The power required is not that high and the power available from a SEP solar array is quite enough to power such a system. It will probably take a commercial mission to do such a survey.

    Dennis

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