[HN Gopher] A theory that Mars lost its magnetic field and then ...
___________________________________________________________________
A theory that Mars lost its magnetic field and then its oceans
(2022)
Author : mannykannot
Score : 150 points
Date : 2023-10-29 14:09 UTC (8 hours ago)
(HTM) web link (bigthink.com)
(TXT) w3m dump (bigthink.com)
| underseacables wrote:
| The 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 wrote:
| > 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
| jvanderbot wrote:
| From 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 wrote:
| We'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 wrote:
| s/\(Mars had\)/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 wrote:
| You're ignoring the possibility that the parent commenter
| is part of a secret time traveling cabal.
| cgriswald wrote:
| This 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 wrote:
| I'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 wrote:
| Ok, we've consed a theory onto the title above.
| ck2 wrote:
| If 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 wrote:
| The 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 wrote:
| Africa 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 wrote:
| They probably are not 2 dimensional
| xwdv wrote:
| If 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 wrote:
| Yes, 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 wrote:
| magnetosphere 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 wrote:
| The remedy would be to put up a magnetic field in the L1
| Lagrange point.
|
| It's an option for terraforming Mars.
| api wrote:
| I'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 wrote:
| Human capacity and human will are, however, rarely aligned.
| Many great things we can do with collective efforts, but
| this is not our society.
| JohnMakin wrote:
| What would power it?
| slashdev wrote:
| You have 24/7 solar power in space
| JohnMakin wrote:
| The energy requirements to generate a large enough
| magnetic field to shield an entire planet from radiation
| is many orders of magnitude higher than any reactor we
| already have on this planet can produce, let alone from
| solar power, and let alone the energy requirements from
| cooling, etc. In other words, this is science fiction. It
| isn't something we even know we could do.
| queuebert wrote:
| We do lose our field periodically. IIRC it reverses over the
| course of ~100-1000 yr every 20,000 yr or so. During that time,
| the field is multi-polar and complex and doesn't shield us
| well. We're still here, nevertheless.
| dylan604 wrote:
| what would this do to radio communications during that course
| of readjusting?
| withinboredom wrote:
| Heh. What radio?
| wheelerof4te wrote:
| Let's say that we would need an alternative to Internet by
| then.
| xwdv wrote:
| In a world where long distance electronic communication
| is no longer possible, packets of data must be delivered
| physically from place to place.
|
| The people who deliver these packets still go by the
| name...
|
| _Courier_.
| wheelerof4te wrote:
| I, for one, wish we'd go back to physical storage media
| such as DVDs, Blue-Rays and CDs.
|
| It made you value the content so much more.
| Zenst wrote:
| It 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 wrote:
| The major force keeping our core hot is nuclear fission.
|
| https://blogs.scientificamerican.com/observations/nuclear-fi...
| JackMcMack wrote:
| Interesting read. Though it says the nuclear fission happens
| in the crust and mantle, not the core.
| idlewords wrote:
| Here'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
|
| "On the Distribution and Variation of Radioactive Heat
| Producing Elements Within Meteorites, the Earth, and
| Planets"
| rvilim wrote:
| You'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.
| yongjik wrote:
| Well, yes, but it basically means the core is wrapped in a
| heat-producing blanket (the rest of the Earth), so we can
| say that the fissile materials on the outer parts of the
| Earth does keep the core stay warm.
| BurningFrog wrote:
| That's what my physics instincts tell me. It might take
| centuries for heat to conduct across the planet interior,
| but it has nowhere else to go.
|
| I'm open to being told my instructions are wrong in this
| case though.
| rvilim wrote:
| I wouldn't say that the best way of thinking about it is
| the blanket analogy because conduction is _not_ the
| primary way that the earth sheds heat, convection in the
| mantle is.
|
| Though I haven't run the numbers, I would strongly bet
| that the core would be _hotter_ than it is right now if
| the mantle did not have internal heating.
|
| The reason being that, the rate at which you remove heat
| from the core (e.g. the rate at which the core cools) is
| entirely determined by the rate at which mantle
| convection removes heat. Radiogenic heat is a _strong_
| driver of mantle convection in the earth, without
| radiogenic isotopes you would get much more sluggish
| mantle convection and a much lower rate of heat removal
| from the core.
|
| The reason for this is twofold:
|
| - Internal heating leads to higher temperatures which
| leads to lower viscosity and more vigorous mantle
| convection - Internal heating will locally heat cold
| "blobs" and make the buoyant
|
| I would also (much less strongly) bet that plate
| tectonics would not occur without internal heating. We
| only see plate tectonics in a narrow slice or parameter
| space in mantle convection models and once you get plate
| tectonics you get _much_ more heat removal and _much_
| faster cooling.
| perihelions wrote:
| Err, that SciAm author misunderstood that research... what
| they wrote is exactly backwards. The neutrino observations
| they're talking about _disproved_ the natural nuclear reactor
| hypothesis. There is no antineutrino signal from the Earth of
| the type a nuclear fission process would emit.
|
| https://arxiv.org/abs/1909.02257 ( _" Comprehensive
| geoneutrino analysis with Borexino"_)
|
| What Borexino found was about 25 terawatts of radioactive
| decay occurring inside the Earth--alpha decay of 238U and
| 232Th. But, no nuclear fission. If there are fissioning
| critical masses inside the Earth, the total amount,
| constrained by neutrino counts, is no more than 2.4 terawatts
| (and consistent with 0).
| pkaye wrote:
| From what I understand Mars is smaller mass than earth so it
| cooled faster. I can imagine other factor like lower gravity
| that makes it easier for the atmosphere and water to easily
| escape to space.
| Modified3019 wrote:
| If you're looking for curious concepts, with no real way to
| test and verify, you could consider that because of the whole
| heliosphere thing our solar system has going on, there are
| higher and lower areas of current flowing through space, and
| planets could potentially act like a resistor in some
| circumstances, which could be gained or lost.
|
| Thus far though, science seems mostly satisfied with
| radioactive decay _Edit_ :
| https://news.ycombinator.com/item?id=38061230 and the things
| rvilim mentions
| photochemsyn wrote:
| The 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-...
|
| 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 wrote:
| Woke 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
|
| (Mars starts almost exactly 2 hours in)
| JohnMakin wrote:
| This 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 wrote:
| Even if it was lost rapidly, rapid would be on the order of
| 10,000 years.
|
| That's a whole human history
| novalis78 wrote:
| It'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 wrote:
| It would be easier and cheaper to terraform/save our own
| planet than to do this. There is no point.
| ch4s3 wrote:
| I 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 wrote:
| The 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.
| anonuser123456 wrote:
| The Great Filter is not likely an astroid or gamma ray
| burst type phenomena but rather the nature of
| intelligence that evolves in a competitive environment
| via evolution. Having two planets full of hyper
| competitive, violent social apes just means having two
| planets plagued by petty infighting. And if one planet is
| insane enough to nuke itself, what's to say it won't nuke
| the other?
| jwells89 wrote:
| If humans have a big enough presence on a second planet
| for there to be wars, we've almost certainly spread
| throughout the rest of the solar system and potentially
| have even put generation ships en route to other star
| systems, so even if earth and mars are nuking each other
| humanity will persist.
|
| That scenario is somewhat unlikely anyway simply because
| access to resources is so much greater at that point,
| with there being thousands of times more of anything we
| have on earth in the asteroid belt and other parts of the
| solar system.
| actionfromafar wrote:
| Isn't it also very human to fight over _control_ over
| those resources?
| jwells89 wrote:
| When supply is short enough to warrant it and control is
| a realistic possibility, sure. Even if humans mastered
| spacefaring tomorrow neither would be true for many
| centuries. The scales involved are utterly unfathomable.
| wyldfire wrote:
| Spoken like a true inyalowda. Maybe we skip the nukes and
| just send some rocks, sasa ke?
| pstuart wrote:
| War is typically fought over limited resources. Getting
| to the proposed step would imply we have a handle on our
| inner solar system: https://hir.harvard.edu/economics-of-
| the-stars/
| leptons wrote:
| >War is typically fought over limited resource
|
| Citation needed
|
| The wars we've seen most recently have nothing to do with
| limited resources. Most wars through history have been
| about ego/ambition of royal assholes, and
| hatred/religious differences. Neither world war was about
| limited resources.
|
| > _" Most wars are not fought for reasons of security or
| material interests, but instead reflect a nation's
| 'spirit'"_
|
| https://blogs.lse.ac.uk/europpblog/2013/07/16/most-wars-
| are-...
|
| While it is possible future wars might be fought over
| limited resources, that hasn't really been the main
| factor in most wars that we know of dating back at least
| 1000 years.
| matwood wrote:
| Interesting. Something like 'spirit' is tough to define.
| WWII could be categorized as a nation's spirit and
| revenge, but would Hitler had been able to whip up the
| nationalism required if Germany had been overflowing with
| resources and was prosperous?
| r3trohack3r wrote:
| This planet has a clock that is running out.
|
| If left to itself, even if humans never evolved on this
| planet, Earth dies in roughly 500m years. A complete total
| extinction event, as the carbon cycles break down and life
| on earth slowly starves.
|
| More than 75% of the time life gets to enjoy on this planet
| is behind us.
|
| 500m years seems like a long time. It is not. 75% of life
| has passed us by, and we have only a single species so far
| that looks like it might be printing a golden ticket to get
| life off this rock. If this exercise fails, either another
| species rises to the calling (squids maybe? Idk), or
| everything goes extinct.
|
| Human intervention on this planet is necessary. And getting
| life off this planet is necessary.
|
| Advocating for anything else is advocating for letting all
| life on earth die.
| nativeit wrote:
| *Citations very much needed to pretty much everything you
| just said.
| withinboredom wrote:
| Exact numbers vary... but I think it safe to say no
| matter what, it's beyond our capabilities to understand.
| Either way, eventually the "sun goes boom" and we need to
| be long gone, or dead, as a species.
| r3trohack3r wrote:
| https://en.m.wikipedia.org/wiki/Timeline_of_the_far_futur
| e
|
| A good entrance to the rabbit hole.
| jwells89 wrote:
| It's not an either/or choice, we should do both, if only
| because learnings from performing planetary engineering on
| Mars will benefit similar efforts on Earth, but also
| because there's no point in pigeonholing ourselves into a
| single planet. We're cavepeople to Earth's metaphorical
| cave and it would be wise to venture beyond it to become a
| true spacefaring civilization.
| pstuart wrote:
| I wish I had more upvotes to give you.
|
| We have the people and resources to to this, and the
| payoff is literally astronomical.
|
| A big question would be how to divvy everything up.
| wiseowise wrote:
| Why is it always the same argument with you people? They're
| not mutually exclusive. We must save our planet and we must
| terraform other planets.
| GolfPopper wrote:
| My understanding is that the biggest challenge with
| terraforming Venus is the atmosphere. It's roughly 93 times
| the _mass_ of Earth 's, and mostly CO2. What do you do with
| it? Cycling it into the crust would take geologic spans of
| time. If you just cool it, you get deep oceans or thick
| glaciers of CO2 covering the planet. If you've got the energy
| budget to actually remove it from Venus completely (or
| sequester it rapidly), you've probably got the energy budget
| to do something easier like relocate a moon or dwarf planet.
|
| Sure, 50-60km up in the atmosphere it's fairly hospitable,
| but colonizing that isn't terraforming.
| holoduke wrote:
| You would split it to o2 and carbon. The real issue is the
| rotation speed of venus. Almost a year to rotate arround
| its axis.
| cgriswald wrote:
| What do you do with a 95% oxygen atmosphere with now only
| ~60 times the mass of Earth's atmopshere? You could make
| a small ocean out of it, but that's a huge amount of H to
| source.
| bloopernova wrote:
| I've often wondered if it would be possible to spin Venus
| faster to shorten its day. Possibly by firing millions of
| large asteroids past Venus at just the right angle.
|
| Added bonus is that you can mash all those asteroids
| together to give Venus an Earthlike moon.
|
| Plus I wonder how such large scale gravitational
| engineering would affect the rest of the solar system.
| asdff wrote:
| You would be bombarded with radiation without a magnetosphere
| javajosh wrote:
| I'd personally be more interested in colonizing Venus. What
| would happen if we construct a large disc and put Venus in the
| shadow of it? It would cool over time and we could assess what
| to do then. Perhaps it still has a dyanmo in its center? Active
| plate tectonics? Water in unexpected places? Venus is very
| similar to Earth's size, much closer than Mars, and if we could
| cool it down and terraform it, a better Earth 2 than Mars.
|
| Plus a version of such a disc might come in handy for Earth, if
| we cannot get warming under control.
| bilsbie wrote:
| I'm thinking genetically engineer organisms to transform most
| of the co2 to a stable solid form.
|
| Maybe floating organisms that can live in the cooler upper
| atmosphere.
|
| Only catch is we'd need to provide a lot of water. I don't
| think the atmosphere has much.
| javajosh wrote:
| Building a disc to shadow venus is possible today. I don't
| think we currently have the ability to create the organisms
| you describe.
| SV_BubbleTime wrote:
| >Building a disc to shadow venus is possible today.
|
| News to me.
|
| Just ignoring all the reasons this seems unlikely.
| Wouldn't it be constantly pushed away from the sun
| towards Venus?
| cgriswald wrote:
| I read a paper (that I can't seem to find now) that suggested
| putting such a sunblock up to freeze out all the CO2, then
| covering the CO2 with 'tarps' and putting the oceans on top
| of the tarps to lock all the CO2 in place.
| Kostic wrote:
| Bulletproof but not a vulcanoproof solution.
| Kostic wrote:
| Kurzgesagt had a nice video about that[0] (and the Mars
| terraforming as well[1]).
|
| [0] https://m.youtube.com/watch?v=G-WO-z-QuWI
|
| [1] https://m.youtube.com/watch?v=HpcTJW4ur54
| anonuser123456 wrote:
| https://astrobiology.nasa.gov/news/how-to-give-mars-an-atmos...
| samuelec wrote:
| A 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"
| dang wrote:
| OK, we've changed the URL from https://daily.jstor.org/how-
| mars-lost-its-magnetic-field-and... and put the year above.
| Thanks!
| weberer wrote:
| I never thought I'd see the day when JSTOR becomes blogspam.
| bilsbie wrote:
| Odd 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 wrote:
| https://astronomy.stackexchange.com/questions/10189/why-did-...
| queuebert wrote:
| Both 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 wrote:
| It'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 wrote:
| Wait 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/10.1029/2022.
| ..
| queuebert wrote:
| Thanks for the link -- I hadn't seen that. My issue is that
| water lost faster than delivered by comets is bad for
| tectonics, which is bad for atmospheric CO2. They'd have to
| show no net loss of water, or else the system is not stable
| over Gyr timescales.
| lamontcg wrote:
| > This "runaway" feedback loop is one of the main reasons why
| global warming should be avoided, in my opinion.
|
| The Earth has had a 4,000-7,000 ppm CO2 concentration in the
| atmosphere before and it hasn't led to Venusification. We've
| only gone from ~250 to ~420 ppm so far, so we're a long way
| off, and hopefully we'll stop before we dump another 20+
| "industrial revolution units" of CO2 into the atmosphere.
|
| Of course long before then we melt Antarctica and the Earth's
| climate looks a lot different, but it won't be Venus.
| c22 wrote:
| In 1860 atmospheric co2 was at 288 ppm [0]. By 1960 it was
| around 317 ppm [1]. A difference of 29 ppm which works out
| to about 226.78 gigatons of co2 [2].
|
| In 2022 we emitted 37.5 gigatons of co2, up 0.9% from 2021
| [3]. We are currently emitting an "industrial revolution"
| of co2 every ~6 years.
|
| [0]: https://www.chicagotribune.com/news/ct-
| xpm-2000-05-23-000523...
|
| [1]:
| https://www.statista.com/statistics/1091926/atmospheric-
| conc...
|
| [2]: https://www.quora.com/How-many-grams-of-CO2-are-in-
| the-atmos...
|
| [3] https://www.statista.com/statistics/276629/global-
| co2-emissi...
| jmclnx wrote:
| There 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 wrote:
| Yep, the article is behind the times. The lack-of-magnetic-
| field hypothesis isn't even the preferred one anymore I
| believe.
| leptons wrote:
| Venus' 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.
| wheelerof4te wrote:
| Not 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 wrote:
| I wonder if these oceans were made of water or some other liquid.
| actionfromafar wrote:
| Water
| wheelerof4te wrote:
| Probably water, but of different composition to that of Earth's
| water.
| musha68k wrote:
| > 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-bui...
| londons_explore wrote:
| Such 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 wrote:
| Wouldn't it still protect humans who visit (or stay on) Mars
| from the solar radiation?
| Levitz wrote:
| That makes sense though. I can hardly imagine any effort put
| 10.000 years ago that would be valuable now, with the
| technological difference.
| reactordev wrote:
| Yeah humans can measure progress afterwards but are
| terrible planners for anything beyond ourselves and next of
| kin.
| bobthepanda wrote:
| I 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.
| withinboredom wrote:
| People still do some maintenance on the 8k year old
| Afghanistan water system (underground aqueducts) because
| they are still used today. I'm failing to find some good
| sources, but when I was there in 2008, it was something
| the Army Core of Engineers was investigating on my base.
| bobthepanda wrote:
| That solves an immediate need though, not a once in a few
| ten thousand year disaster.
| kaz-inc wrote:
| this[1] places them at 3k years old:
| https://en.m.wikipedia.org/wiki/Qanat
| withinboredom wrote:
| That sounds more right to me than a memory of some random
| conversations from nearly 20 years ago.
| SV_BubbleTime wrote:
| You could write exactly what this is and what you're
| supposed to do with it on a big stone plate outside...
|
| Then in 10,000 years, find that an entire religion,
| culture, and wars were built around the simple
| maintenance instructions.
| bobthepanda wrote:
| Outside, on Mars.
|
| So we have to assume we will maintain the ability for
| human Mars travel in ten thousand years, that anyone can
| read English or whatever in ten thousand years, and that
| the supporting religion didn't lose any of its wars.
|
| To put this in perspective our first evidence of any
| human agriculture was 12,000 years ago.
| blamestross wrote:
| Progress is exponential until "surprise it is a sigmoid!"
| I'd argue we are there already, but even if we aren't
| planting seeds is rarely a waste in the long term.
| dehrmann wrote:
| Only 5,000, but look at the pyramids. They're cool to look
| at, and the construction is fun to think about, but they're
| utterly useless. For any sort of 10,000 year space project,
| there's little (1%) harm in having a 100-year cool-off
| period to see if it still makes sense and how far
| technology has come.
| pchristensen wrote:
| Road networks in cities are probably the most durable
| creations.
| fnordpiglet wrote:
| I'm not sure I understand why you think this would take 10's
| of thousands of years to yield benefit. The most important
| benefit is shielding the planet surface from solar radiation
| and cosmic rays. This would be immediately beneficial to
| anyone living on the surface and would be essential in any
| terraforming effort of any duration, long or short. There are
| proposals that terraform mars in the span of a few
| generations (orbital solar powered large lasers evaporating
| the iron oxide and melting the ice for instance). But even
| without terraforming making the surface less hostile has
| immediate benefits.
| Loughla wrote:
| All of the terraforming business always seems like just
| digging around in your belly button.
|
| We can't even fix the problems on our first planet. How
| (and why) can we even begin to think about another one?
| wiseowise wrote:
| There's a lot why's to do that. How is the question.
| c22 wrote:
| I guess if we do develop terraforming technologies I'd
| rather we test them on Mars first.
| mortehu wrote:
| We have solved countless problems on our planet. What are
| "the problems" you are thinking of?
| bsder wrote:
| > We can't even fix the problems on our first planet. How
| (and why) can we even begin to think about another one?
|
| For precisely this reason?
|
| We can't stop asteroid impacts. We can't stop a well-
| adapted plague, either (Ref: Covidiots). We have
| dictators with nuclear weapons that we can't stop. etc.
|
| Having a self-sufficient colony somewhere other than
| Terra is almost certainly the first step toward avoiding
| a "Great Filter" event.
| api wrote:
| > We can't even fix the problems on our first planet. How
| (and why) can we even begin to think about another one?
|
| By this logic we never go. There will always be giant
| seemingly insurmountable problems. If we solve climate
| change there will just be another, and another, and
| another. Life is a never ending fight against entropy.
| There will never be a time when we have it all figured
| out.
|
| Secondly it's entirely possible that the stuff we learn
| trying to survive off world will be applicable to making
| life here more sustainable. It could force us to figure
| out how to run industry efficiently with a very high
| percentage of material recycled, and how to run an
| economy without a lot of low entropy ecosystem to draw
| from. Also no fossil fuel. They don't exist. We'd only
| have nuclear and solar really.
| fnordpiglet wrote:
| Because life deserves redundancy?
| thejackgoode wrote:
| A hundred years? I feel like 90% of what happens is done
| because of election cycles and quarterly reports
| londons_explore wrote:
| People build bridges today that are expected to still be
| standing in 100 years.
|
| They could have made it a bit weaker, not bothered with
| paint or inspection hatches, and saved a little money, and
| had it only last 25 years...
|
| The time-value of money says that any benefit 25+ years
| from now is almost worthless, so it probably wasn't worth
| spending anything on those things to make the bridge last
| longer.
|
| Yet in most cases we still tend to build it to last 100
| years, despite the economist saying it isn't worth it.
| moffkalast wrote:
| Probably not the best example since once a bridge is
| built you can immediately use it, the benefits don't only
| start rolling in after a 100 years. Making sure something
| lasts is correlated with natural disaster safety margins
| anyway so if it has to be built to survive near term
| extremes it'll generally also survive a while as a side
| effect. Older constructions also seemingly last longer
| through survivorship bias and the lack of computer
| modelling at the time meant that safety margins had to be
| higher.
|
| A better example are maybe tree avenues that take decades
| to grow into anything useful, or maybe long term river
| redirection projects or reactors. ITER's still in
| construction after 16 years. But there's just about
| nothing we do that would take more than a few decades to
| start showing returns.
| elliotto wrote:
| I'm not sure what the rules are in the US but in
| Australia the infrastructure service life is set by
| regulation. It's not an economic / financial argument or
| even a benevolence / moral argument that causes this,
| it's a legal requirement. There are significant real
| world advantages of having a bridge last more than 25
| years that are not reflected by a financial return on
| investment.
| ozim wrote:
| I don't think we really have most bridges built to last
| 100 years. What I see most is built to last 50 years and
| then usually it is stretched by patching/fixes or
| ignoring the issues as those will be passed on to whoever
| is in charge politically when a bridge finally fails.
| Yizahi wrote:
| As soon as that technology level is reached, humanity need not
| to worry about restoring dead ecosystems, but about preventing
| total destruction of the existing ones, including Earth.
| Throwing space rocks will be trivial for any terrorist cell, so
| any fragile single points of failure will be demolished first
| (like this magnetic shield, or possible Earth solar
| shade(because carbon capture doesn't work so far)). Then
| orbital stations will go, then pressurized domes, then planet
| surfaces in general.
|
| I think we have no chance at the large space structures, and
| current age will be considered a fluke of the insufficient
| lifting capabilities.
| aeternum wrote:
| Seems like redundancy could solve this. Instead of a single
| huge magnet you create a constellation of smaller magnets
| with aligned fields that orbit the LaGrange point.
|
| We're decent at tracking large space rocks, and small space
| rocks will likely have to be dealt with anyway since some
| occur randomly.
|
| It's somewhat interesting that terrorism already isn't such a
| problem for huge skyscrapers. Skyscrapers can be destroyed
| with just a small fraction of the explosive energy required
| to launch an orbital rocket yet it rarely happens.
| natpalmer1776 wrote:
| Your last paragraph is an excellent point that highlights
| the likely risk factor by using existing infrastructure as
| an example.
| slibhb wrote:
| If throwing space rocks is trivial (which I'm not sure I
| buy), surely knocking them off course will also be trivial.
| bobse wrote:
| Hypothesis, not theory. FFS...
| jasongill wrote:
| isn't a theory just a hypothesis that's supported by research?
| the article mentions the published research about this theory
| (or hypothesis, I suppose)
| bobse wrote:
| No. Learn2Science.
| dehrmann wrote:
| In this context, this isn't the semantic hill you want to
| die on.
| johnea wrote:
| But for some reason people still want to live there?
|
| Since you'll have to live underground anyway, why not just live
| in Nevada?
| spandextwins wrote:
| Humans?
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