How would we get Mars' core going again?

[Mirannan]

I think for the answer we need a magnetics expert. If someone can find one let me know. I recently needed specific information about strength and the field of a rare earth magnet we have custom made from a magnetic manufacturer and they couldn't answer the simple questions.

I did manage to find this small piece of some interest.
http://www.ti.com/lit/ml/slup123/slup123.pdf

I'm not sure anything about the magnetic properties of rare earth alloys would be relevant to this discussion anyway. The reason is that permanent ferromagnetism (the sort we see in magnets) is dependent on the temperature of the magnet (or lump of metal you want to be a magnet) being below a certain point called the Curie point which is different for each alloy.

Planetary cores, including that of Mars, are big lumps of nickel-iron alloy. The temperature of even Mars's core is almost certainly well above the Curie point of this material. For reference, the Curie point of iron is 1043 K and that of nickel is 627 K. (Isn't Wikipedia great? )

Planetary magnetism is caused by a dynamic process, namely currents in the liquid part of the core caused by the rotation of the planet. The precise mechanism of this causation is unknown AFAIK. For Earth, the liquid is iron; for Jupiter and Saturn it is liquid metallic hydrogen. Mars has a weak residual field, probably generated by such materials as magnetite (Fe3O4) in its crust.

So to give Mars a significant magnetic field, one would need to re-melt the core. The energy required for this would be astronomical - literally. And getting the heat to the core without completely devastating the surface of Mars would be a problem, too.

Incidentally, Venus has very little magnetism for a different reason. Venus is almost the same size as Earth, and probably has a core about the same size too. But its rotation is so slow that the currents to generate the magnetic field just haven't formed. So to give Venus a magnetic field would involve spinning it up. Also astronomical in scale.

 

[BAYLOR]

Incidentally, Venus has very little magnetism for a different reason. Venus is almost the same size as Earth, and probably has a core about the same size too. But its rotation is so slow that the currents to generate the magnetic field just haven't formed. So to give Venus a magnetic field would involve spinning it up. Also astronomical in scale.

In the case of Venus , theytheorize that the every 500 million years, the planet heats up turns itself completely inside out.

 

[Mirannan]

In the case of Venus , theytheorize that the every 500 million years, the planet heats up turns itself completely inside out.

Yup. There are three speculative reasons for the Earth/Venus difference I've heard; of course they could all be operating. The first is that Earth's tectonic plate system crucially depends on fairly large amounts of water in material being subducted, which essentially lubricates the crustal motions involved. Venus, of course, has virtually no water. The second is that Venus's almost complete lack of rotation alters crustal dynamics compared to Earth. And the last is that tidal flexing of Earth's crust makes a difference. (This is also connected to Earth's fast rotation.)

None of this alters the matter of whether Venus's core has a liquid component. I don't know how this could be found out; the internal structure of Earth was discovered by seismometry, and dropping seismometers on Venus (that last more than a few minutes, anyway) is challenging to say the least!

But a liquid core doesn't help unless it is circulating.

 

[Ray McCarthy]

Perhaps we should pick an easier project than Mars. Anyone fancy any Real Estate on any of Jupiter's Moons?

 

[BAYLOR]

Perhaps we should pick an easier project than Mars. Anyone fancy any Real Estate on any of Jupiter's Moons?

Europa Gardens.

 

[Mirannan]

Europa Gardens.

Bit of a problem with Europa if you want to terraform it. The problem being that if you raised it to Earthlike temperatures it wouldn't have a solid surface. That's apart from the nuclear-reactor levels of radiation...

 

[BAYLOR]

Bit of a problem with Europa if you want to terraform it. The problem being that if you raised it to Earthlike temperatures it wouldn't have a solid surface. That's apart from the nuclear-reactor levels of radiation...

I though Europa had a solid surface. They have theorized that we might possibly find life on Europa given that there are oceans of water there beneath the ice.

 

[tinkerdan]

What I was referencing was::

I'm not sure anything about the magnetic properties of rare earth alloys would be relevant to this discussion anyway. The reason is that permanent ferromagnetism (the sort we see in magnets) is dependent on the temperature of the magnet (or lump of metal you want to be a magnet) being below a certain point called the Curie point which is different for each alloy.

:: the notion that magnetism just like gravity is a big unknown and that I wouldn't rule out that you could position platforms on space to generate magnetic fields that would create the desired effect of simulating a magnetosphere, but that would probably be about the same time we figure out how gravity works and then that would change everything anyway.

 

[Mirannan]

I though Europa had a solid surface. They have theorized that we might possibly find life on Europa given that there are oceans of water there beneath the ice.

Yup. Europa's surface is solid. Solid ice, which means that terraforming Europa would melt the ice. Incidentally, the ocean is thought to be 100km or so deep so planting colonies on the sea floor is also out of the question barring some serious advances in materials science.

 

[BAYLOR]

What we need to do is find the planet Mangrathea . Let them install a new core in Mars, It would be maintenance free for long time.

 

[BAYLOR]

Mars had a larger moon , that might provide the gravity to heat up Mars's Core.

 

[Vertigo]

I don't think that would be enough. I think you would have to have a 'moon' that is significantly larger than Mars to get this effect. In other words instead of moving a moon to Mars I think you'd have to move Mars to Jupiter.

As far as I know the Earth's core temperature is comes mostly from decaying radioactive isotopes; a process that will eventually die down and Earth will cool. However I think the timescale for this is comparable to that for the expansion of the Sun so I suspect it is probably not something Gaia need worry too much about!

 

[Mirannan]

I don't think that would be enough. I think you would have to have a 'moon' that is significantly larger than Mars to get this effect. In other words instead of moving a moon to Mars I think you'd have to move Mars to Jupiter.

As far as I know the Earth's core temperature is comes mostly from decaying radioactive isotopes; a process that will eventually die down and Earth will cool. However I think the timescale for this is comparable to that for the expansion of the Sun so I suspect it is probably not something Gaia need worry too much about!

AFAIK there is a fairly big contribution from phase changes at the core/mantle boundary and also at the inner/outer core boundary, both of which release heat.

 

[Vertigo]

I'm sure you probably know more on this than myself @Mirannan so you're probably right. Either way I don't think the gravitational effects of a larger moon would cut it. Ultimately to be thinking of doing something like this I suspect means we're trying to figure ways of fighting entropy.