Molten Core of Mars: Could Tidal Action from a Moon Create a Magnetic Field?

[Bill McKeeman]

TL;DR Summary

If Ceres were a moon of Mars, would Mars have a molten core?

Mars apparently does not have a molten core, therefore no magnetic field.
If Mars had a substantial moon, say Ceres, would the tidal action melt the core in Mars?
And, perhaps, allow Mars to retain an atmosphere.

 

[mathman]

Seems highly unlikely. What is the physics behind your idea?

 

[Bill McKeeman]

Physics: distorting a solid object produces heat. Our moon distorts our planet, at least at the surface. I am wondering how much of the internal heat in our planet is generated by distortion. I have read that radioactive decay is another source of deep heat. Primordial heat will eventually dissipate.

 

[davenn]

Summary: If Ceres were a moon of Mars, would Mars have a molten core?

Mars apparently does not have a molten core, therefore no magnetic field.

this is an incorrect statement ... It does have a molten core
there's dozens of hits on google talking about this

I am wondering how much of the internal heat in our planet is generated by distortion.

Not the main contributor

. I have read that radioactive decay is another source of deep heat.

Again, not the main contributor. It does help to heat the core and mantle,
But the major reason that the core is molten is because it occurred that way when the Earth formed
out of the Solar Nebula.

Primordial heat will eventually dissipate.

well the Sun is likely to go red giant before the Earth's core cools. The rock above is an extremely
good insulator

 

[phinds]

https://www.physicsforums.com/find-threads/unanswered

Summary: If Ceres were a moon of Mars, would Mars have a molten core?

Mars apparently does not have a molten core, therefore no magnetic field.
If Mars had a substantial moon, say Ceres, would the tidal action melt the core in Mars?

It seems much more likely that if any such thing were to happen, it would be the core of the moon that would heat up. The planet has a lot more mass to dissipate the generated heat.

 

[Vanadium 50]

I don't think this is possible.

If the Earth's liquid outer core were to freeze, could the tides thaw it? No. The total kinetic energy of the moon is only about 30% of what it would take to re-thaw it.

For Mars you gain a factor of 8 for the mass you need to melt, but you immediately lose it again with the weaker Martian gravity producing slower orbits. Then you lose another factor of 5 because of Ceres mass. There just isn't enough energy in the system to do what you want, so how you couple it doesn't make much difference.

Of course, the better reason (as mentioned before) you can't do this is that Mars' core is already liquid.

 

[Damo ET]

I don't think this is possible.

If the Earth's liquid outer core were to freeze, could the tides thaw it? No. The total kinetic energy of the moon is only about 30% of what it would take to re-thaw it.

For Mars you gain a factor of 8 for the mass you need to melt, but you immediately lose it again with the weaker Martian gravity producing slower orbits. Then you lose another factor of 5 because of Ceres mass. There just isn't enough energy in the system to do what you want, so how you couple it doesn't make much difference.

Of course, the better reason (as mentioned before) you can't do this is that Mars' core is already liquid.

I'm not too sure if that is correct.

IIRC the main source of lingering internal heat for all of the terrestrial planets is the radioactive decay of elements. If the source is too small (Mercury, Mars, Pluto, Moon*) the core solidifies as the heat available at formation radiates from the body quicker than the radioactive decay can account for. The core cools, and the dynamo set up from the molten core/outer core disappears. With it, so too does the atmosphere as it gets blown off by the solar wind,

Edit:
I can't attach the scholar search I did, here is a copy of the abstract:

Abstract

If internal heating in the mantle of Mars is similar to that in the Earth, solid‐state convection is the mechanism preventing large scale melting of the Martian mantle. Convection is efficient enough in transporting heat to preclude the existence of a liquid core and hence a dynamo driven intrinsic magnetic field, if the viscosity of mantle material is lower than 1022‐1023 cm²/sec at temperatures in excess of about 1500°C. The Martian lithosphere is probably several hundred kilometers thick, intermediate in size between that of the Earth and Moon.
As for planets/moons 'using' tidal forces to keep the core warm (not sure if this includes molten) you have to have a massive body like Jupiter or Saturn, and closely orbiting moons.
Io, is the one that springs immediately to mind, where volcanism is it's main feature. Europa and Enceladus are the other two which have enough internal heat to have liquid water under the surface ice.Damien

 

[davenn]

IIRC the main source of lingering internal heat for all of the terrestrial planets is the radioactive decay of elements.

As I said earlier, that is incorrect. only about 50% of it can be accounted for by radioactive decay,
there are plenty of links on google about that.

If the source is too small (Mercury, Mars, Pluto, Moon*) the core solidifies as the heat available at formation radiates from the body quicker than the radioactive decay can account for.

Again, as I stated earlier, Mars has a molten core

 

[phinds]

As I said earlier ...
Again, as I stated earlier ...

I'm getting the feeling that nobody listens to you

 

[davenn]

I'm getting the feeling that nobody listens to you

story of my life

 

[Damo ET]

As I said earlier, that is incorrect. only about 50% of it can be accounted for by radioactive decay,
there are plenty of links on google about that.
Again, as I stated earlier, Mars has a molten core

I read what you stated, without knowing what you do or don't know, it makes it irresponsible of me to take your word for it (or anything for that matter without a little research). As for using google to verify anything, sure, but you can verify that the Earth is flat with it too. So I went to a source "Google scholar" which I figured I could use without prior expertise to determine if I was on the right path. As it turns out, it "seems' there is a little disagreeance with whether it is, or isn't, a solid.
From what I thought I understood, our magnetosphere is generated in the motion of the liquid iron outer core of the Earth. With Mars' magnetosphere going away (based on it's past atmosphere and current very weak magnetic field) as a layperson, I tied both these together.

Obviously it is far more complicated than the simplistic idea I have in mind, so how does Mars maintain its liquid core but lose its magnetosphere?

I am listening. :)

 

[davenn]

I read what you stated, without knowing what you do or don't know, it makes it irresponsible of me to take your word for it (or anything for that matter without a little research). As for using google to verify anything, sure,

Ohh boy …. there's a ton of scientific data for a molten Mars core …
time you learned how to do research

. As for using google to verify anything, sure, but you can verify that the Earth is flat with it too.

OMG, you really are in another world

There is NO scientific evidence on the net for a flat earth

Please stop deceiving yourself

 

[phinds]

I read what you stated, without knowing what you do or don't know, it makes it irresponsible of me to take your word for it (or anything for that matter without a little research).

So why did you come to this forum and ask questions if you plan on ignoring the answers?

As for using google to verify anything, sure, but you can verify that the Earth is flat with it too.

No, you cannot. You CAN verify that there are nut cases on the Internet

If you are unable to distinguish between good and bad references, you should focus on learning that before anything else.

 

[Damo ET]

"this is an incorrect statement ... It does have a molten core
there's dozens of hits on google talking about this"

Since when did the burden of proof fall onto those who you state are wrong?

As I wrote earlier (as a point only) if confirmation bias is used, 'you' can find "dozens of hits" via "google" on anything you want (including the Earth being flat). BTW, I don't remember saying that I think the Earth is flat, or that I am compelled by the "evidence" google gives for it.

Does "google scholar" not conform to what you 2 think is reasonable to believe? And if so, my statement stands, that it seems that whether Mars' core is molten or not is not clear cut.

I am still waiting for a link/page/study/citation/website/ literally anything would be better than "Again, as I stated earlier, Mars has a molten core".

"So why did you come to this forum and ask questions if you plan on ignoring the answers?"

As any good Bayesian should do, update what they think with better more compelling evidence. Sorry, but one persons say so with no corroborating evidence doesn't carry much weight. Then you managed not to read the rest of my reply, nice.


It is also a little disheartening that you 2 decide to disect a reply, and focus on the trivial while dodging the real questions.

As I also stated, I am a layperson with a layperson understanding, so if you have detail, share it.Damien

 

[sophiecentaur]

story of my life

Sorry Dave, I can't hear you. Did you say something?

 

[davenn]

Since when did the burden of proof fall onto those who you state are wrong?

Always

As any good Bayesian should do, update what they think with better more compelling evidence. Sorry, but one persons say so with no corroborating evidence doesn't carry much weight. Then you managed not to read the rest of my reply, nice.

nor did you so don't even go there

if you can't do some basic research from peer reviewed sources, then I'm not going to hold your hand
and walk you through it

here at PF, we encourage people to do their own research and come back with questions
rather than just spoon-feed them the answers I did, but in light of your earlier comments ... a response wasn't worth the effort That's it ... I'm done with this

 

[Dragrath]

I read what you stated, without knowing what you do or don't know, it makes it irresponsible of me to take your word for it (or anything for that matter without a little research). As for using google to verify anything, sure, but you can verify that the Earth is flat with it too. So I went to a source "Google scholar" which I figured I could use without prior expertise to determine if I was on the right path. As it turns out, it "seems' there is a little disagreeance with whether it is, or isn't, a solid.
From what I thought I understood, our magnetosphere is generated in the motion of the liquid iron outer core of the Earth. With Mars' magnetosphere going away (based on it's past atmosphere and current very weak magnetic field) as a layperson, I tied both these together.

Obviously it is far more complicated than the simplistic idea I have in mind, so how does Mars maintain its liquid core but lose its magnetosphere?

I am listening. :)

That is the wrong question the right question here if looking to understand what is going on is why do Mercury and Earth have a magnetosphere? In both cases the leading theory is that there is a solidifying inner core which is re energizing convection within the core resulting in the continued presence of a global magnetic field. The smallest body to possesses a molten core remnant from its formation is our Moon as determined by analysis of the Apollo era seismology experiments. Mars is more massive and thus should be less efficent at losing heat than our Moon and thus by Occam's razor it seems likely to expect that Mars will have a molten core as both the Moon and Mercury have one. Thus the most likely explanation for the lack of a magnetic field for differentiated planets is a lack of convection within the planets core. One of the goals of the Insight mission is to answer this question with a higher degree of certainty.

https://www.nasa.gov/topics/moonmars/features/lunar_core.html
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019GL082677
At the very least the moon confirms a world can have a molten core but lack a geomagnetic field

 

[Damo ET]

Interesting. From what I found, the magnetic field of Mercury represents around 1.1% of what the Earth has, which is still strong enough to set up a magnetosphere to deflect the solar wind. Also, another I found seems to suggest that the Moon's outer core may be being kept "warm" from the tidal forces of the Earth on it.

https://en.wikipedia.org/wiki/Mercury's_magnetic_field
https://phys.org/news/2014-08-hot-moon-tidal-deepest-lunar.html

Thanks for your reply.

 

[Tom.G]

Excerpt from:
https://mars.nasa.gov/news/453/scientists-say-mars-has-a-liquid-iron-core/


Researchers at NASA's Jet Propulsion Laboratory, Pasadena, Calif., analyzing three years of radio tracking data from the Mars Global Surveyor spacecraft , concluded that Mars has not cooled to a completely solid iron core, rather its interior is made up of either a completely liquid iron core or a liquid outer core with a solid inner core. Their results are published in the March 7, 2003 online issue of the journal Science.


Cheers,
Tom