Mars Magnetic Dynamo: New Timeline

Guest “remote astro-geology” by David Middleton

MAVEN Mission Overview

It’s very well established that in the distant past, Mars had enough surface water to erode and deposit a wide range of fluvial sedimentary features, including mudstone (a pretty good indication of past life). In order for Mars to have had liquid water at the surface, it would have had to have had a much thicker and warmer atmosphere. It has long been thought that Mars lost its atmosphere after its magnetic dynamo shut down and it was blown away by the solar wind.

When did the Martian dynamo die?
Posted on November 7, 2012 by rburnham

Current thinking among Mars scientists holds that the Red Planet’s dynamo — the geo-engine in its molten core which generates a global magnetic field — was active soon after the planet formed, but turned off about 4 billion years ago.

Spacecraft in orbit have detected and mapped magnetic fields in parts of the ancient southern highlands and elsewhere. While these show no active global dynamo pattern, they indicate that Mars had an internally generated magnetic field at one time. Yet the field disappeared at some point because the Hellas, Argyre, and Isidis impact basins — about 4 billion years old — contain no magnetic signatures. These would have been printed into the impact-melted rocks if a global field had been present when the basins formed.

But is this ancient age in fact correct? New work by a team of scientists led by Colleen Milbury (Purdue University) and published in the Journal of Geophysical Research suggests the dynamo shutdown happened more recently. If true, this means that Mars kept its magnetic field longer — and this would have protected the atmosphere for longer as well.

A magnetic field strong enough to leave traces in once-molten rocks would deflect most energetic solar radiation and ionizing particles, thus preventing them from eroding the atmosphere. But when the dynamo died, the Martian atmosphere began to die with it. Today’s Mars has no global magnetic field, only a thin atmosphere, and solar radiation and particles can strike the surface unhindered, making conditions hostile for most forms of life.

[…]

Red Planet Report

Researchers at the University of British Columbia have now proposed that the dynamo was active during two geologic time periods, approximately 4.5 and 3.7 billion years ago (Ga).

UBC researchers establish new timeline for ancient magnetic field on Mars

SCIENCE, HEALTH & TECHNOLOGY

May 1, 2020    |   For more information, contact Erik Rolfsen

Mars had a global magnetic field much earlier—and much later—in the planet’s history than scientists have previously known.

A planet’s global magnetic field arises from what scientists call a dynamo: a flow of molten metal within the planet’s core that produces an electrical current. On Earth, the dynamo is what makes compass needles point north. But Mars’ dynamo has been extinct for billions of years.

New findings from UBC researchers working with colleagues in the U.S. and France, published today in Science Advances, bring us closer to knowing the precise timing and duration of Mars’ dynamo.

[…]

The new data for this study come from MAVEN, the Mars Atmosphere and Volatile Evolution satellite. Earlier data about magnetism on Mars had been gathered by the Mars Global Surveyor satellite which orbited the planet between 1999 and 2006, mostly at 400 kilometres above the surface. MAVEN, launched in 2013, operates as close as ~135 kilometres from the surface and picks up weaker signals that MGS could not detect.

MAVEN’s ability to pick up signals from smaller features on and near the surface helps researchers distinguish whether the magnetism is coming from those, or from older rocks buried more deeply in the planet’s crust.

These new insights have researchers wondering what could be revealed if they get even closer. Mittelholz noted that this study focused on two particular features, but craters remain all over Mars with stories to tell. In the future, exploration could progress from satellites to drones or balloons, providing even more detailed data.

University of British Columbia
Fig. 1 Dynamo timing scenarios.An early dynamo “[a]” predating Hellas, Isidis, and Argyre (1). The basin age range is shown according to the isochron (cyan) and N(50) (blue) age (47). Early dynamo termination by 4.13 Ga “[b]” is based on magnetic field signatures of a larger basin population (78). The age of magnetization of meteorite ALH84001 [3.9 to 4.1 Ga; (48)] overlaps the early dynamo time frame “[c].” A late dynamo “[d]” postdating the major basins (913). New constraints from MAVEN data (stars) over the BB, around the Utopia basin, and LP that indicate a dynamo at ~4.5 and ~3.7 Ga. The timing of Utopia is uncertain (dotted line). The map displays Mars Observer Laser Altimeter topography (49) with BB, Utopia, and LP marked (stars).” Mittelholz, et al., 2020

The second active dynamo phase at 3.7 Ga would be coincident with the Early Hesperian Period:

Pre-Noachian Represents the interval from the accretion and differentiation of the planet about 4.5 billion years ago (Gya) to the formation of the Hellas impact basin, between 4.1 and 3.8 Gya.[10] Most of the geologic record of this interval has been erased by subsequent erosion and high impact rates. The crustal dichotomy is thought to have formed during this time, along with the Argyre and Isidis basins.

Noachian Period (named after Noachis Terra): Formation of the oldest extant surfaces of Mars between 4.1 and about 3.7 billion years ago (Gya). Noachian-aged surfaces are scarred by many large impact craters. The Tharsis bulge is thought to have formed during the Noachian, along with extensive erosion by liquid water producing river valley networks. Large lakes or oceans may have been present.

Hesperian Period (named after Hesperia Planum): 3.7 to approximately 3.0 Gya. The Hesperian Period is marked by the formation of extensive lava plains. The formation of Olympus Mons likely began during this period.[11] Catastrophic releases of water carved extensive outflow channels around Chryse Planitia and elswhere. Ephemeral lakes or seas formed in the northern lowlands.

Amazonian Period (named after Amazonis Planitia): 3.0 Gya to present. Amazonian regions have few meteorite impact craters but are otherwise quite varied. Lava flows, glacial/periglacial activity, and minor releases of liquid water continued during this period.

The date of the Hesperian/Amazonian boundary is particularly uncertain and could range anywhere from 3.0 to 1.5 Gya.[12] Basically, the Hesperian is thought of as a transitional period between the end of heavy bombardment and the cold, dry Mars seen today.

http://palaeos.com/precambrian/martian_timescale.html

The Yellowknife Bay formation is thought to have been deposited during the Early Hesperian Period in a “strikingly Earth-like habitable environment.”

At Yellowknife Bay there is no hint of the strongly acidic conditions that have been thought to especially describe the planet’s younger history of aqueous alteration, sedimentation, and habitability (74, 83, 91). The record of aqueous activity at Yellowknife Bay is likely prolonged and complex, involving several stages of diagenesis, including clay formation, that culminate with precipitation of calcium sulfate salts in veins, but without attendant indicators of acidic waters such as iron sul-fates. The simplest interpretation of the sequence of diagenetic events would involve progressive desiccation of mildly saline, pH neutral waters—a very Earth-like scenario (92). Such conditions have been envisaged for the very early history of Mars (91), but it is only recently that they have been considered viable for a younger age (7, 93, 94). The surprising result is that the stratigraphy of Yellowknife Bay may not only preserve evidence of a habitable environment, but one that is relatively young by Martian standards. In the most conservative scenario allowed by geologic mapping, the Yellowknife Bay formation represents part of the older fill of Gale crater, and therefore roughly Early Hesperian in age (6), perhaps overlapping with or post-dating times of bedded sulfate formation elsewhere on Mars. This would indicate that times of sustained surface water, neutral pH, and authigenic clay formation extended later into Mars’ history. The potentially young age of clay formation (and habitability) does not invalidate the general trend that most rocks that interacted with water early in Mars’ history produced clays, and those that interacted later produced sulfates. However, much like Earth’s time-dependent records of iron formation (95, 96) and carbonates (97, 98), it points to the need to understand those special conditions which allow a distinctive aqueous environment to persist for broad spans of geologic time, or to recur when the favorable conditions again emerge. Curiosity’s detection of a relatively young, and strikingly Earth-like habitable environment at Gale crater underscores the biologic potential of relatively young fluvio-lacustrine environments.

Grotzinger et al., 2014

References

Grotzinger, J. P., Sumner, D. Y., Kah, L. C., Stack, K., Gupta, S., Edgar, L., … Yingst, A. (2014). A habitable fluvio-lacustrine environment at Yellowknife Bay, Gale crater, MarsScience343(6169). https://doi.org/10.1126/science.1242777

Mittelholz, A., C. L. Johnson, J. M. Feinberg, B. Langlais, R. J. Phillips. Timing of the martian dynamo: New constraints for a core field 4.5 and 3.7 Ga agoScience Advances, 2020; 6 (18): eaba0513 DOI: 10.1126/sciadv.aba0513

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68 thoughts on “Mars Magnetic Dynamo: New Timeline

  1. Why no wonder re possible human-type creatures existing on the planet when its environment possiby able to sustain life “as we know it”?

    • It took billions of years after life first emerged on Earth before multi-celled critters showed up. Truely complex life forms didn’t come into existence until some 200 to 300 million years ago.

      Unless life evolved orders of magnitude faster on Mars compared to the Earth, then there wasn’t time for complex life to form on Mars.

    • If Mars had or even had life, it’s probably stuck in the anaerobic stage.

      Cellular life on Earth enjoyed big transitions that probably didn’t happen on Mars, to wit, photosynthetic bacteria, producing free O2; eukaryotes, ie large, complex unicells with nuclei, bacterial-derived mitochondria and othe plastids, such as chloroplasts’; multicellular eukaryotes, ie plants, fungi and animals, let alone complex, intelligent animals.

      • Hi John
        After Covid-19, if Musk ever gets anyone on Mars, leave them up there for ever, we have enough of the Chinese microbes down here.

        • IMO viruses aren’t microbes, since not generally considered alive, ie biological.

          My personal opinion is that they should be considered alive, but that’s very much a minority view. Nevertheless, even those who regard them as nonliving replicants speak of killing them and of their life cycle.

          A grey area.

      • Some manner of chemosynthetic life would be far more likely than photosynthetic life.

  2. Mars is a warning about what happens when you leave nature completely to itself. The only hope for life is that humans will develop sufficiently that, when Earth’s time comes, they can find a way to keep all life from perishing.

    Human beings are Gaia’s greatest creation and Gaia’s greatest ally. The greenies have it exactly backward.

    • Well we would say that wouldn’t we?
      Blue Whales might have a different idea.

      And when earth’s time comes, enveloped by an expanding sun, we hope for our descendents’ sakes that they’ve got the starships ready and the motors running…

    • Humans left nature to itself for 99.9999% of the time the Earth has existed. During that time, nature did a pretty good job without our help. But the conditions for nature to succeed remained excellent on Eath and became poor on Mars and other planets.

      So what’s the best prognosis for the future of life on earth? With or without humans? By producing humans did nature create its own saviour or its destroyer? Or are humans ultimately irrelevant – nature will go on, or disappear due to over-riding factors (such as the magnetic dynamo stopping) regardless of what humans do. What will happen to humans? On the balance of probabilities, we will go extinct just like the majority of species that have ever existed.

      If you think that humans are or will be capable of saving nature, do you also think they are capable of causing global warming? After all, most commentators at this blog consider that’s not possible. And if humans couldn’t possibly be raising the Earth’s temperature a few degrees, how likely is it that they would be able to stop the magnetic dynamo slowing and the atmosphere disappearing, even in a future ‘developed’ state?

      • “If you think that humans are or will be capable of saving nature, do you also think they are capable of causing global warming? After all, most commentators at this blog consider that’s not possible. And if humans couldn’t possibly be raising the Earth’s temperature a few degrees, how likely is it that they would be able to stop the magnetic dynamo slowing and the atmosphere disappearing, even in a future ‘developed’ state?”
        Humans have to save “nature”, but some sentient life, like AI, doesn’t. Anyways,
        we living in an Ice Age, there zero consequence to life if Earth returns to it’s warmer state.
        An Ice Age causes dangerously low levels of CO2, there is no consequence to life if Earth returns to it’s higher levels of CO2

      • “Humans left nature to itself for 99.9999% of the time the Earth has existed. During that time, nature did a pretty good job without our help.”

        Sure, if we ignore all those damn impact events and massive global ice ages that pretty much wiped out everything. How likely is it that human’s do anything positive or negative to save nature? Well, depends on what you mean by save nature. Is Mars Natural? Is that what we are going to save, Mars in its current natural state? Why not Mars in its natural state 4 billion years ago.

        Reading your illogical statements posing as questions, I am quite sure that you don’t give a damn about saving nature. Your interest is to just throw monkey poo around, which I guess is a natural thing to do for some animals.

        • Frenchie77: In answer to your initial quote from my post – the impacts and ice ages certainly caused extinction events, but look at what happened next. Those extinction events opened up opportunities for new species to evolve and spread. Mammals, for example, were small and few while the dinosaurs dominated the land. After the impact event knocked most of them out, mammals blossomed, eventually producing us humans. Some small dinosaurs survived and took over the air as birds.

          So, in this sense, ‘nature’ did do a good job without our help. Note that I was using ‘nature’ in this way only because this was the wording used in commieBob’s post which I was responding to.

          The rest of your comments are confusing. I don’t think humans can ‘save nature’. My post was saying exactly that, again in response to commieBob.

          • So nature changes and adapts, hmmm, funny that. I thought we were trying to save nature by locking it in place.

      • humans can neither “save nature” nor “cause global warming”. What humans are good at it is affecting their local environment to mitigate the effects of the overall environment they live in. irrigation, damning rivers, building sea walls, cutting down forests, farming, building shelter, air conditioning/heating, etc (all of which requires cheap, reliable energy – ie mainly fossil fuels). So while they can’t stop the atmosphere disappearing, they could build contained living environments on this world before the atmosphere goes poof or (in theory) colonize other worlds (though currently there are no better worlds in reach, hence the in theory part, though a loss of atmosphere might just change the criteria for what is considered a better world).

  3. Like Mars, Venus doesn’t have a magnetic field. Why does Venus still have an atmosphere?

      • Thanks for that link, David. That’s the best explanation of this process I have seen so far.

      • They detected a very weak effect – good for them. But it does not explain why the planet still has its very dense atmosphere.

        • Since Venus has no intrinsic magnetic field to act as a shield against incoming charged particles, the solar wind sometimes interacts directly with the upper atmosphere. However, Venus is partially protected by an induced magnetic field.

          As on Earth, solar ultraviolet radiation removes electrons from the atoms and molecules in the upper atmosphere, creating a region of electrically charged gas known as the ionosphere. This ionised layer interacts with the solar wind and the magnetic field carried by the solar wind.

          During the continuous battle with the solar wind, this region of the upper atmosphere is able to slow and divert the flow of particles around the planet, creating a magnetosphere, shaped rather like a comet’s tail, on the lee side of the planet

          Spacecraft observations over many decades have shown that magnetic reconnection occurs frequently in the magnetospheres of Earth, Mercury, Jupiter and Saturn. This process, which converts magnetic energy into kinetic energy, occurs when oppositely directed magnetic field lines break and reconnect with each other. On Earth, this reconnection is responsible for magnetic storms and polar auroras – the so-called Northern and Southern Lights.

          Until now, reconnection was not generally thought to occur on non-magnetised planets. However, Tielong Zhang and an international team of co-authors now report on Science Express, the online version of the journal Science, that they have found the first evidence of magnetic reconnection in Venus’ magnetotail.

    • Mars has only 38% while Venus has about 91% of the surface gravity on Earth.
      Although the solar wind is much stronger at Venus’ distance, so is the UV providing a strong equatorial electrojet on the day side, inducing protective magnetic field repelling solar particles that strip high atmosphere’s low energy gas particles. Due to the high temperatures on the Venus surface, there is also strong vertical (up/down) gas circulation (equivalent to Hadley or Ferrel circulation on Earth) , with stronger gravity only small proportion of gases gets high enough to get cold enough (loss of kinetic energy) to be blown away by the solar wind.

  4. “solar radiation and particles can strike the surface unhindered, making conditions hostile for most forms of life.”

    Tardigrade: hold my beer

    • Yes a Tardigrade can go into long-term hibernation, a state where metabolic (energy deriving-producing) processes have all but ceased… only because its genome (while safely tucked away in some deep ice formation) is not getting blasted by ionizing radiation while it sleeps.

      If you knew anything at all about DNA repair processes, you’d know that DNA repair is an active on-going, energy (mucho ATP and GTP used) consuming process. DNA repair under ionizing radiation requires an active metabolism. So when a tardigrade goes to hibernation, its genome is vulnerable. As any organism’s would be without active repair of DNA lesions casued by a steady bombarment of izonizing radiation. Bottom-line: You can’t do both. And organism can NOT shut-down energy metabolism AND repair DNA lesions under a steady bombardment of ionizing radiation.. Shit down metabolism, and eventually the genome becomes too riddled with defects to be viable when the organism is revived by favorable conditions. This fact is one of the key downfalls of Science Fiction of long space travel hibernation. Wihout active metablosim, radiation-induced DNA lesions build-up past the point of organism viability.

      • “If you knew anything at all”

        Really, Mr. O’B? This is your response to a JOKE? You must be great fun at parties.

        • I realize it was a meant as a joke, the “hold my beer” joke.

          But I get annoyed when people think Tardigrades can survive in space or unshielded planet surfaces in a state of suspended animation just because they can do that here on Earth safely shielded from the ionizing radiation of space.

  5. “Humans left nature to itself for 99.9999% of the time the Earth has existed. During that time, nature did a pretty good job without our help”

    Next minute:

    “On the balance of probabilities, we will go extinct just like the majority of species that have ever existed”

    So does nature do a pretty good job without our help, or does she kill almost everything she makes? Time for human intervention before she turns all bunny boiler on us.

    We don’t have the ability or technology to alter the temperature of the planet to any measureable extent; our puny efforts are dwarfed by natural variation, but we will need technology on that kind of scale if we are to survive for the foreseeable future.

    • “We don’t have the ability or technology to alter the temperature of the planet to any measureable extent; our puny efforts are dwarfed by natural variation, but we will need technology on that kind of scale if we are to survive for the foreseeable future.”

      If we were in middle of glaciation period, could humans bring the world into an interglacial period?

      It would seem impossible as long human were not a spacefaring civilization. Of course if human were a spacefaring civilization, they might not be in hurry to return Earth to an interglacial period, but they could if they wanted to.
      How do you do it?
      You would have to warm the oceans.
      The ocean in glacial period could have an average temperature of about 2 C. And currently we about 3.5 C. So if warm entire ocean up by 2 C, that should do it.

    • Colin, Yes, given that the majority of species have in fact gone extinct, in fact you could say of ‘nature’ that ‘she kills almost everything she makes’.

      Of course ‘nature’ as an anthropomorphised female ‘she’ does not exist, this is just a labelling used by some humans. I only used the concept because I was satirising commieBob’s usage of it.

      Anyway, commieBob’s idea of a future ‘developed’ human who can save life on earth implies a new species of human, and that implies that our species, H. sapiens, will no longer be around, but extincted, that is dead, http://www.montypython.50webs.com/scripts/Series_1/53.htm . Maybe a few of our genes will hang on in the future new species, just like we have some Neanderthal genes.

    • We don’t have the ability or technology to alter the temperature of the planet to any measureable extent…

      We could easily lower the average surface temperature. We have long had the ability and technology to block incoming solar radiation.

    • “Evolutionary Theory” says we should keep getting more and more species.

      Obvious empirical data show that we have lost magnitudes more species than are currently walking or flying around. This observation is more in line with Bible creation explanation than with “Evolution.”

      Yet, we have faith in “Evolution.” Pondering this helps understand the meaning of the word “faith.”

      • No faith is required to observe the fact of evolution. No evidence exists supporting the irreconcilably contradictory biblical creation myths. All the evidence in the world shows them counterfactual.

        The fact of extinction helped scientists understand the reality of evolution. New species arise as prior ones go extinct. Sometimes mother species continue despite the evolution of daughter species, but eventually most if not all species go extinct or evolve into new ones. Evolution results from reproduction.

        That life on Earth has generally become more diverse, despite most of its species having gone extinct, should not be surprising. Obviously, after mass extinction events, fewer species survive than existed briefly previously. But the four billion year trend is toward more diversity. This trend will probably reverse in less than another billion years, unless intelligent life forms intervene to keep Earth habitable.

  6. Start with a sputtering, dying magneto-dynamo… add in some conjecture… a dash of speculation… a full heaping of making shit up… viola!! Life on Mars.

    Speculation heaped onto conjecture using just a wee bit of evidence as the key ingredient.
    In science, that’s called an overly broad interpretation.

    • It’s actually… Voila! Extremely solid evidence of habitable conditions on Mars approximately 3.7 billion years ago. Whether or not some form of life evolved on Mars, is a question that probably won’t be answerable until we have the capability to bring back suites of rock samples.

    • Speculation heaped onto conjecture using just a wee bit of evidence as the key ingredient.
      In science, that’s called CAGW

      Fix that for you.

    • Venus lost its water because it was a hellhole, if it has always rotated as slowly as it does now. The main reasons that the planet’s surface is so hot are its slow rotation rate and dense atmosphere, which keeps its night side practically as hot as the lit hemisphere. Heat probably also travels through its lithosphere.

      It might also have once had an internal magnetic field to help hold onto its water. In that case, it might have suffered a moist GHE.

  7. The idea of burning all the world’s oil and gas in a giant conflagration to stop the imminently expected onset of an ice age, by dramatically increasing CO2 in the atmosphere and thus warming the planet, was thought up in the 1970s and rejected because (to roughly quote Fred Hoyle) the Earth’s climate is relatively insensitive to CO2 levels. Anything changed? No.

    Mars is interesting and I just hope I live long enough to see the first humans go there. Is this study actually saying that Mars’ dynamo was active in two separate periods with an interval between? Surely not, probably just that we haven’t yet detected magnetic evidence from the interval between.

    If we ever got to the stage of thinking about restarting the dynamo to engineer Mars for surface habitation perhaps we could do it by loading up some large asteroids to provide new moons for Mars and start a gravitational pull (Marsquakes anyone?). It works well enough elsewhere in the solar system.

    Is a large moon the reason Earth’s core is still active? Perhaps we should be worrying about the Moon drifting off a few cm a year – maybe a more pressing problem than global warming of an unmeasurable from noise micro-degrees increase.

    Can we really speculate meaningfully about how quickly life might have developed on Mars? I doubt it.

      • The interpretation of the Mars Rovers’ data that the surface of Mars had flowing water on it is not universally accepted;

        https://www.nature.com/articles/news051219-10

        I thought Burt and Knauth raised some valid points, at the time, but nobody likes a wet blanket. A wet Mars, yes, but not a wet blanket.

        • They even agreed in 2005 that there was flowing water. The question was whether or not it was over a prolonged period of time.

          But it is unclear whether all the water on Mars came in sudden bursts a long time ago, when meteorites battered the ice deposits of the young planet, or whether some stood about in warmish puddles later in Mars’ life, which might have given life time to evolve.

          Since then, the bulk of the evidence has pointed to one or two prolonged wet periods.

  8. Won’t be long before the nexgen bedwetters come up with Catastrophic Anthropological Global Magnetism Change! The end of life on earth! Seas boiling, skies falling, cats and dogs living together!

    It’s the Magnetism Crisis Stupid!

    No more electricity powered goods of any kind! Big Power, particularly GE, has known about this for decades! We need a UN IPMC and Compo! Now!

    • The north magnetic pole is on an accelerated march northwest out of the Canadian Arctic towards Siberia. Those pesky Russians are stealing the north magnetic pole now. In 2007, the latest survey found the pole over Ellesmere Island. During the 20th century it moved 1,100 km (680 mi), and since 1970 its rate of motion has accelerated from 9 to 52 km (5.6 to 32.3 mi) per year.

      Reversal occurrences are statistically random. There have been 183 reversals over the last 83 million years. The latest occurred 780,000 years ago, and may be on the path to a reversal at some point again in the near geologic future. The overall geomagnetic field is becoming weaker; the present strong deterioration corresponds to a 10–15% decline over the last 150 years and has accelerated in the past several years; geomagnetic intensity has declined almost continuously from a maximum 35% above the modern value. This must have some significant effect on climate over longer time terms., perhaps from incoming space weather or effects from the Sun.

      I have not heard anyone in the climate community comment how how this might make climate change part of natural variation except perhaps for Henrik Svensmark’s theory on the effects of cosmic rays on cloud formation as an indirect cause of global warming and/or cooling, being a natural cause.

      • Current climate science can’t see the forest because it is fixated upon a single tree, while caught up in consensus and political aristocracy.
        Don’t expect the Scientology Synod of Anthro-climate Guilt to ponder facts that don’t support their meme, that might provide a clue their claims are never quite what they seem.

  9. Why was there flowing water and not glaciers 3.7Billion years ago given that the Sun had lower output then ( or so I have read) and Mars is further from the Sun than Earth? Y’all going to tell me it was the CO2 are you not?

      • Doesn’t mention N2, maybe because not considered a GHG. But nitrogen could have increased surface pressure, helping to keep liquid water on the surface, and the GHG H2O in the air.

        Once the dynamo spun down, N2 could have escaped the low gravity and been stripped by the solar wind. Dinitrogen gas of course has only about 2/3 the mass of carbon dioxide molecules.

  10. Under how many ways can the universe kill a planet: Maybe a magnetar did its thing to Mar’s atmosphere?

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