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A theory that Mars lost its magnetic field and then its oceans (2022)
- underseacables 3y agoThe headline is a little misleading. It is only a theory that Mars lost its magnetic field. The experiment that was done was on earth, simulated, and so the researchers cannot definitively say that Mars ever had a magnetic field and lost it.
- usrbinbash 3y ago> and so the researchers cannot definitively say that Mars ever had a magnetic field We know that Mars had a dynamo-effect in the past from various measurements of the magnetization in its crust, indicating that it had a magnetic field. https://en.wikipedia.org/wiki/Magnetic_field_of_Mars https://en.wikipedia.org/wiki/Magnetic_field_of_Mars
- jvanderbot 3y agoFrom my understanding, the evidence for Mars magnetic field is well established from measurements of ejecta and rock banding. Estimates differ on the strength of the field but I'm not sure there's disagreement on whether there ever was one.
- candiodari 3y agoWe've analysed old rocks, both from Mars itself and from meteorites and they are magnetized ... so Mars had a magnetic field, for ~1.5 billion years after it's formation. We also know that for at least the 1st billion years mars had an ocean. In fact, it was probably covered 100% in water for the larger part of that 1.5 billion years.
- jonhohle 3y agos/\(Mars had\)/it seems \1/ s/know/think/ When people state things as absolutely true at a cosmic scale that we can’t possibly know with any certainty except what our collectively minimal knowledge allows us to hypothesize, it shuts down discussion, discourages dissent (important in sciences, imho), and taints everything else with suspicion (again, imho, if so-and-so was so certain about thing x we now know is wrong, why should I believe anything they’ve said).
- queuebert 3y agoYou're ignoring the possibility that the parent commenter is part of a secret time traveling cabal.
- cgriswald 3y agoThis sort of moralizing is counterproductive, wrong, and dripping with irony when you talk about shutting down discussion. "Idea is only a theory," when talking about science is almost always a misunderstanding of the word theory and a conflation with the words hypothesis or hunch or guess. Mars previously having a magnetic field isn't dogma. It's the best explanation we have for the evidence. It is knowledge. Dissent is more than welcome if it can offer new evidence, prove why the existing explanation is wrong, or better explain the existing evidence. Until then, it is much more correct to say "Mars had" than "Mars didn't have". "It seems" undersells it and is pointless hedging akin to saying "It seems species change over time in response to environmental pressures due to natural selection." > (again, imho, if so-and-so was so certain about thing x we now know is wrong, why should I believe anything they’ve said). Because you're not an irrational loon? Who do you know who has never been certain and wrong about anything? In the case of science, look at the evidence. No one is asking you to believe the boy who cried wolf when he tells you the sky is made of marshmallow.
- icehawk 3y agoI'd actually posit that this sort of post shuts down discussion even more. It doesn't provide any sort of useful information that complements or refutes the point in question. It's useless naval-gazing that doesn't actually actually add anything to the conversation-- as there is nothing that we perceive directly, and anyone seriously discussing it should know the limitations of inference.
- dang 3y agoOk, we've consed a theory onto the title above.
- ck2 3y agoIf I understand correctly, Earth got very lucky with whatever massive planet ("Theia"?) crashed through in early formation to give us the huge core (hence magnetic field for particle deflection) and our absolutely massive moon to churn things. Seems like both might be needed for "life", maybe anything more than microbes? Mars core is only half the size of earth's
- hinkley 3y agoThe latest density surveys of the earth’s core lead people to claim that chunks of Theia are still discernible in the mantle and outer core. There are splotchy chunks of higher density material down there. And by chunks I mean at least half the size of Australia to almost the size of Africa.
- codeflo 3y agoAfrica and Australia describe areas, and the word "chunks" implies volumes... I have no idea whether you mean to imply those chunks are very flat, or that they are in fact volumes with a diameter similar to the width of continents.
- s1artibartfast 3y agoThey probably are not 2 dimensional
- hinkley 3y agoTake your well achtually’s back to Reddit, dude. You have nested shells in a sphere. Like a couch on moving day, there are only so many shapes that will fit around a corner and still be substantial. If they weren’t substantial no reasonable person would call it a chunk the size of Africa. Or just google it.
- codeflo 3y ago> Take your well achtually’s back to Reddit, dude. I guess you're somehow convinced that such an infallibly good explainer that any question for clarification must come in bad faith. > Like a couch on moving day, there are only so many shapes that will fit around a corner and still be substantial. That defines the geometry perfectly, glad you explained it so clearly. > Or just google it. Yeah, why waste time reading your comments.
- xwdv 3y agoIf Earth lost its magnetic field, how long would we last? My understanding is these sort of geological scale events would take thousands of years. Maybe a million.
- jwells89 3y agoYes, atmospheric loss driven by solar wind is a very slow process. It’s the only reason why anybody entertains ideas of thickening the Martian atmosphere… the loss is slow enough that if a civilization has the means to do that kind of planetary engineering, maintenance to offset losses is trivial. Intuitively I’d expect it to be faster in the case of Earth due to it being so much closer to the sun but I don’t know this for certain.
- asdff 3y agomagnetosphere also shields you from cosmic radiation. long term human settlement would have to be in shielded dwellings, easiest built underground, making the logical case much stronger for just becoming troglodytes on a dying earth than attempting to revive a dead mars as troglodytes.
- BurningFrog 3y agoThe remedy would be to put up a magnetic field in the L1 Lagrange point. It's an option for terraforming Mars.
- api 3y agoI’ve seen some math that suggests that this or perhaps even doing it on the surface with superconducting rings near the poles would take less energy than you might think. If I recall correctly it was something like the power grid output of the state of California. A lot but entirely within human capacity. If it were space based you’d have a ton of free continuous solar power.
- asdff 3y agoHuman capacity and human will are, however, rarely aligned. Many great things we can do with collective efforts, but this is not our society.
- Zenst 3y agoIt always fascinates me the inner core of our planet, after all it is from what we know a swilling mass of hot melting metal and other elements. Which is ever so slowly cooling at a size and scale we find hard to imagine. Are their events that bring about rapid cooling, or are there mechanisms that maintain or induce the heating, scale of planet and subsequent pressure, or perhaps even cosmic rays impact it are thoughts, but the deeper we look, the more questions we find and still a case of solve less answers than questions and yet to reach that point in which we fully understand it. Perhaps and very probably, Mars was a thriving ecosystem whilst the earth was still a molten blob of rock. Just the scale of time in the universe well outpaces biological life when talking billions of years.
- BurningFrog 3y agoThe major force keeping our core hot is nuclear fission. https://blogs.scientificamerican.com/observations/nuclear-fission-confirmed-as-source-of-more-than-half-of-earths-heat/ https://blogs.scientificamerican.com/observations/nuclear-fi...
- JackMcMack 3y agoInteresting read. Though it says the nuclear fission happens in the crust and mantle, not the core.
- idlewords 3y agoHere's a survey paper with a deeper treatment of the topic, for Earth and other solar system bodies: https://link.springer.com/article/10.1007/s11214-020-00656-z https://link.springer.com/article/10.1007/s11214-020-00656-z "On the Distribution and Variation of Radioactive Heat Producing Elements Within Meteorites, the Earth, and Planets"
- rvilim 3y agoYou've got to be careful here. This article refers to the heat budget of the _entire_ earth, not the Earth's core. The Earth's core has relatively little in the way of radiogenic elements now. Most of the heat originating in the core comes from - The formation of the earth (called primordial heat) - Latent heat (released when iron freezes onto the solid core) - Differentiation (e.g. settling of heavy stuff to the bottom) The mantle is chock full of radiogenic elements though.
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- photochemsyn 3y agoThe notion that the Earth's atmosphere would rapidly be stripped away if the magnetic field vanished is very unlikely. There's a lot of complex chemistry and physics that control rates of atmospheric escape from planets - but here's an accessible overview: https://www.scientificamerican.com/article/how-planets-lose-their-atmospheres/ https://www.scientificamerican.com/article/how-planets-lose-... Basically the intensity of sunlight (distance from the Sun) relative to the gravitational field of the planet are the main factors. Magnetic fields play a minor role at best, by trapping charged water-sourced hydrogen ions - but those ions can easily lose their charge and then escape to space: > "An important process for hydrogen loss is “charge exchange”, which probably accounts for about 40 percent of the present escape of hydrogen from Earth and most of the hydrogen escape from Venus. Solar radiation creates electrons and positively charged ions in upper atmospheres by tearing electrons off atoms or molecules. Subsequently, charge attraction and repulsion in collisions accelerates ions. On Earth, the magnetic field traps ions, but a fast hydrogen ion can collide with a neutral hydrogen atom and capture its electron. In this exchange of charge, fast ions turn into escaping neutral atoms." The primary reason Earth doesn't see high rates of hydrogen formation from water and subsequent loss in the upper atmosphere is that the surface temperatures are low enough such that the stratosphere remains very dry. On Mars, due to lower gravity, this stratification should have been less, leading to higher rates of water loss from the upper atmosphere.
- neom 3y agoWoke up to YouTube playing this 3 hour video on space the other day and it happened to be at the mars section so I lay and listened to it for a while, pretty fun watch: https://www.youtube.com/watch?v=eSg7TREgNTA https://www.youtube.com/watch?v=eSg7TREgNTA (Mars starts almost exactly 2 hours in)
- JohnMakin 3y agoThis is why the whole notion of colonizing/terraforming mars is a fantasy. Any humans there would be dead within a fairly short period and terraforming efforts would be futile due to getting blasted away by radiation. If we truly wanted to colonize off-planet, the moon is right there.
- was_a_dev 3y agoEven if it was lost rapidly, rapid would be on the order of 10,000 years. That's a whole human history
- novalis78 3y agoIt’s not a fantasy. Read “A case for Mars” if you are sincerely interested in the topic. Terraforming could dramatically thicken the atmosphere - a process that would take several hundred years. Yes, Mars would slowly lose it, but over 100s of millions of years. So you can keep the planet blue and green. Venus is harder but doable too. Can’t do that with the moon ever. So eventually, if we don’t WW3 ourselves, there will be 3 blue marbles in this solar system and an endless number of space and moon based habitats.
- JohnMakin 3y agoIt would be easier and cheaper to terraform/save our own planet than to do this. There is no point.
- ch4s3 3y agoI think the proponents here are imagining a future a few hundred years from now where we have done that and there are 10s of billions of people in the solar system on multiple planets.
- wyldfire 3y agoThe point is trying to get past the Great Filter. Humanity faces threats from the cosmos beyond the ones we create on this planet. We can do both: work to repair our planet while preparing for colonies on another.
- samuelec 3y agoA mere attempt to improve SEO. The article is a non-news and a non-proof. It also contains recycled content, in fact, on top of the article: "October 12, 2023 ... First Appeared on Big Think" following the link to Big think article we read "September 25, 2023" and "This article was first published on Big Think in February 2022"
- bilsbie 3y agoOdd that Venus has no magnetic field, and it has a very thick atmosphere, even though it gets 4 times the solar flux as Mars.
- contrarian1234 3y agohttps://astronomy.stackexchange.com/questions/10189/why-did-venus-not-lose-its-atmosphere-without-a-magnetic-field https://astronomy.stackexchange.com/questions/10189/why-did-...
- queuebert 3y agoBoth are related, as Venus is thought to have lost its water through runaway greenhouse. Without water, tectonics and vulcanism are likely to cease, and CO2 is unable to be recycled into the deeper layers of the planet. It builds up on the surface, and you get a 70 bar atmosphere of mostly CO2. This "runaway" feedback loop is one of the main reasons why global warming should be avoided, in my opinion.
- soderfoo 3y agoIt's quite terrifying to think of a runaway feedback loop leading to the emptying of the oceans, on the scale of happening within a lifetime.
- Kevin09210 3y agoWait I thought the extreme runaway greenhouse effect had been set aside (read that on here a few years ago IIRC), and it wasn't possible for Earth's atmosphere to turn into Venus'. Found this from April 2023: >How a Stable Greenhouse Effect on Earth Is Maintained Under Global Warming >Plain Language Summary: Observations and model simulations have shown that Earth maintains a stable longwave radiative feedback process. When the surface warms by 1 K, Earth allows for 1.7 to 2.0 Wm−2 of extra thermal cooling to escape to space in cloud-free conditions. Recent studies have claimed that this enhanced thermal cooling to space can be explained by emissions from the surface passing through the atmosphere's infrared window. However, we find that a large portion of the stability actually results from enhanced atmospheric emission during global warming, which arises from the weakening of spectral lines broadening by radiatively inert gases (N2, O2, Ar) as the Earth warms. It is a well-understood phenomenon in spectral physics but has been largely ignored in the feedback literature. As a result, the feedback responses from the thermal radiative effects of greenhouse gases tend to stabilize the climate, rather than initializing a runaway of thermal radiative energy. This study further proposes a simple theory for accurately predicting the clear-sky longwave feedback from climate base states. https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2022JD038124 https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2022...
- jmclnx 3y agoThere is an article in Syy&Telescope that contains a new theory. I did not read it fully yet, but seems Magnetic Field was/is not a factor. It shows Venus, Mars and Earth is loosing isotopes(?) at about the same rate. Plus, Venus has no Magnetic Field to speak of and its atmosphere is far denser than Earths.
- Sharlin 3y agoYep, the article is behind the times. The lack-of-magnetic-field hypothesis isn't even the preferred one anymore I believe.
- leptons 3y agoVenus' atmosphere is mostly carbon dioxide and sulphuric acid which is a far different composition than Earth's atmosphere. My guess is the heavier molecules that make up the atmosphere are what makes it far denser than Earth, and gravity likely has much more to do with it than magnetism.
- dredmorbius 3y agoMars's atmosphere is also predominantly CO2, though far thinner. That's ... somewhat to be expected of any non-life-bearing rocky planet. Free oxygen is unstable, lighter elements (hydrogen, ammonia) would tend to boil off with either low gravity or (relatively) high temperatures (as opposed to the ice-moons of Jupiter and Saturn, especially Titan).
- wheelerof4te 3y agoNot to mention Jupiter's or Saturn's magnetic fields, that are far less dense than Earth's, yet both planets have massive gaseous atmospheres.
- luxuryballs 3y agoI wonder if these oceans were made of water or some other liquid.
- actionfromafar 3y agoWater
- wheelerof4te 3y agoProbably water, but of different composition to that of Earth's water.
- musha68k 3y ago> According to NASA Planetary Science Division director Jim Green, a powerful magnetic dipole positioned at the Mars L1 Lagrange Point could potentially deflect the solar wind like a natural magnetic field. https://www.extremetech.com/extreme/245369-nasa-proposes-building-artificial-magnetic-field-restore-mars-atmosphere https://www.extremetech.com/extreme/245369-nasa-proposes-bui...
- londons_explore 3y agoSuch a project would see no tangible benefits for tens of thousands of years. Unfortunately, humans tend not to put much effort into anything that has no benefits within ~100 years. "If neither me nor my children will benefit from something, I don't want to invest my time/money."
- yincrash 3y agoWouldn't it still protect humans who visit (or stay on) Mars from the solar radiation?
- Levitz 3y agoThat makes sense though. I can hardly imagine any effort put 10.000 years ago that would be valuable now, with the technological difference.
- reactordev 3y agoYeah humans can measure progress afterwards but are terrible planners for anything beyond ourselves and next of kin.
- bobthepanda 3y agoI mean, how would you even do maintenance over 10,000 years? At some point your descendants will be too far to remember the reason but not far enough to need it and they’ll stop wasting resources on a nothing activity.
- bobse 3y agoHypothesis, not theory. FFS...
- johnea 3y agoBut for some reason people still want to live there? Since you'll have to live underground anyway, why not just live in Nevada?
- spandextwins 3y agoHumans?
- neurostimulant 3y ago> Without the magnetic field, the solar wind would strip our atmosphere, and the oceans would evaporate and be lost to space. In other words, Earth would end up like Mars. > The Earth is the only one of the rocky planets in our Solar System to have a strong magnetic field. Its presence is likely one of the major reasons why Mars and Earth are so vastly different. Venus has much denser atmosphere than Earth despite having weaker magnetic field and being closer to sun (possibly more affected by solar wind?). Why?