Solar Storms Obliterated Mars’ Atmosphere

By Andrew Coates University College London | November 5, 2015 5:25 pm
mars

An artist’s rendering of Mars getting bombarded by a solar storm. (Credit: NASA/GSFC)

“Mars ain’t the kind of place to raise your kids – in fact it’s cold as hell,” sings Elton John in Rocket Man. And it’s true: the present atmosphere and surface of Mars are certainly inhospitable for any aspiring rocket man. Since Mars lost its magnetic field 3.8 billion years ago, the pressure of its once Earth-like atmosphere has gradually reduced to just 1% of Earth’s, letting through damaging UV light and cosmic radiation that make the surface a lot less habitable.

We don’t really know how or why this happened. But new results from NASA’s MAVEN mission, published in Science, have shed some light on the mystery – it’s to do with solar storms and shocks from the Sun billions of years ago. There’s a bright side to the new results as well: an aurora over most of the planet’s night-time hemisphere has been discovered.

The Evolution of Habitability

Life on Mars might have developed 3.8 billion years ago, at about the same time as it evolved on Earth. There is growing evidence from NASA and ESA orbiters that virtually all the ingredients for life were present at that time – with water flowing on the surface, carving outflow channels and creating clays and other water-dependent minerals.

But something happened 3.8 billion years ago, probably a large collision with a planet-sized object, to snuff out Mars’ protective magnetic field, leaving only crustal magnetic anomalies mainly in the old southern highlands. These are the evidence of the ancient global magnetic field, which would have protected Mars’ atmosphere and surface from scavenging by the solar wind, as well as from energetic cosmic rays.

Mars as seen by Hubble. (Credit: NASA and The Hubble Heritage Team/Wikimedia)

 

NASA’s MAVEN mission has been at Mars since September 2014, bristling with the instruments needed to study atmospheric escape, which is the loss of gases in the atmosphere to outer space. It is specifically looking at the effects of the solar wind – a gusty, million-ton-per-second flow of charged particles from the sun.

This is helping to reveal the fate of the early Martian water as well as other compounds in the atmosphere. One theory is that it flowed out to space over time, with the solar wind causing this flow to increase and with some of the water being trapped in ice beneath the surface. The early sun was dimmer but more active, with more flares, coronal mass ejections and shocks to interact with anything in its way, including the early Mars.

The researchers studied the impact of a solar-wind shock which passed the planet on March 8, 2015, one of the biggest ever seen at Mars. This increased the amount of gases flowing out from the planet by a factor of ten, supporting theories that solar-wind shocks caused enhanced escape while buffeting early Mars. The higher activity of the Sun billions of years ago means that a big chunk of its atmosphere would have escaped early on.

So did the loss of Mars’ atmosphere wipe out any life that may have existed there? Not necessarily. Recent results from Mars show that salty water seeps on the surface now – but the harsh surface environment means that under the surface is the best place to look for signs of life.

The ExoMars 2018 mission will do just that, drilling two meters under the surface, enough to get below the radiation environment. This may be the haven for past or even present life (albeit less likely). We can’t wait to get our cameras and instruments to the surface in 2019 to test the sub-surface samples in this exciting ESA-Russia mission.

Northern Lights

The MAVEN mission has also discovered a new type of aurora on Mars, similar to some of the ones we see on Earth. Northern Lights occur when the magnetic field of our planet is disturbed by the solar wind, making charged particles travel into the upper atmosphere where they “glow” as they lose their energy. The brightest auroras are called “discrete” auroras but there are also “diffuse auroras”, which glow faintly, if it all.

Mars Express has already discovered that Mars has a discrete aurora. But the new measurements have found that diffuse aurora also take place, away from the polar regions. It is likely that it is all over the planet at night. These aurora are caused by penetrating solar energetic particles hitting the atmosphere, rather than the solar wind. However, both types of auroras are seen in the ultraviolet, meaning they are outside the visible spectrum that can be detected by the human eye.

MAVEN has also made an unexpected discovery about all the dust surrounding Mars. Mars is a dusty planet, with seasonal global dust storms. However, the mission has spotted dust high in the atmosphere, meaning it is not from Mars but from interplanetary sources.

The results are exciting as it is taking us ever closer to tracing the history and fate of the Martian atmosphere. Combined with the results of other missions, this will help settle exactly how habitable Mars was in the past and how habitable it is today.The Conversation

This article was originally published on The Conversation. Read the original article.

CATEGORIZED UNDER: Space & Physics, top posts
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  • OWilson

    Well, at least some scientists acknowledge that solar activity is a major influence on a planet’s atmosphere.

    After all NASA tells us that Mars has Global Warming, too.

    According to a couple of new studies, the Sun’s radiation levels and magnetic fields are more import climate change agent’s than our much maligned life giver, C02.

    Maybe we are getting somewhere :)

    • Mike Richardson

      Mars also lacks a global magnetic field, making it far more susceptible to having its atmosphere stripped away. So which of these studies are showing a greater influence on climate change from solar activity than the “maligned life giver, CO2”? Besides, CO2 becomes a lot less benign at higher levels, unless you’ve learned how to photosynthesize. :)

      • OWilson

        Well, we also have a new scientific model (Zarkhova et al) which says with 97% certainty, we are heading for a mini ice age. Due to a regular lull the solar activity.
        I go with the science.
        Bad news for Global Warming cultists, buy hey!
        As we speak, the northwest Passage is still frozen solid and the likelihood of those folks who anted up a million or so to race a sailboat through, getting their money’s worth is nil.
        Unless Obama loans them the 22 Arctic Ice Breakers, he recently ordered. :)

        • msafwan

          “global warming is fake” cultist…

          • OWilson

            Global warming is what you get after you have been through an Ice Age. We’ve been through many, major and minor, and man has not only survived but thrived.

            That’s what we have now, but it is not catastrophic and certainly not “THE GREATEST THREAT TO HUMAN KIND!”.

            That “End Is Nigh” stuff used to be on church boards, paraded around on sandwich boards, and shouted out by characters of dubious mental alacrity on street corners

            They now have found they can reach far more people on the internet and can stay warm and dry too :)

        • Mike Richardson

          Hoo-boy, you’re betting on that mini ice age thing again?! Sorry, but there’s a lot less evidence in support of that “new scientific model” than the evidence of anthropogenic climate change. Cultists usually don’t go with the theory best supported by evidence, though. Might be projecting a bit, there. 😉

          • OWilson

            Not at all, I am betting that the earth will remain somewhere between the predicted extremes for a long, long, time.

            And, I have been right for the past 50 years or so.

            Seen lots of Doomsday predictions come and go. :)

          • Mike Richardson

            No, if you look at the statistics, you really haven’t been right the last 50 years or so. Particularly for the last 20. Extreme weather events are on the rise, such as Hurricane Patricia and the rather long-lived El Nino in the Pacific. And what is the prediction of a mini ice age, based on much less evidence than that supporting global warming, if not Chicken Little talk? It just seems like you’ve got one standard for you, and a different one for everyone else. By the way, Socrates was better known for rhetoric than logic, so he might not be the best advocate to bring to this debate. Though he is a fitting avatar for you, Wilson. Good evening, my Socratic friend. :)

          • OWilson

            Sigh!

            That image is generally accepted to be Aristotle.

            But I wouldn’t expect a low info voter to know the difference. :)

          • Mike Richardson

            You mean that’s not your actual appearance? And you got to use “low info” again! Yeah, I’m not really the one sounding like a parrot here. Night. 😉

          • OWilson

            If you’re going to lecture on Greek philosophy, it’s always good to get your philosophers straight :)

            They have quite differing views.

            And if I were a parrot I would make a big deal out of your own erroneous “uptick” to your own post. (you’ll have to look for it) just like you did mine.

            But I’m above that petty stuff :)

          • Mike Richardson

            Lol… yep, you’re above the petty fray. Glad we have such mature leaders of discourse here. I do love the irony Wilson, and you always provide plenty. Thanks!

          • OWilson

            You don’t know what irony is until you’ve seen another Al Gore junket for global warming interrupted by the real world :)

          • Mike Richardson

            Irony is your last statement, given all the other things you post here. 😀

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