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Was Life on Mars Extinguished Prematurely by a Huge Impact?

Direct hit - could a huge impact on Mars have snuffed the chances of life? (Karen Carr)

A very deep impact (Karen Carr)

We keep sending missions to Mars with the key objective to search for past or present life. But what if a huge impact early in the Red Planet’s history hindered any future possibility for life to thrive? Recent studies into the Martian “crustal dichotomy” indicate the planet was struck by a very large object, possibly a massive asteroid. Now researchers believe that this same impact may have scrubbed any chance for life on Mars, effectively making the planet sterile. This asteroid may have penetrated the Martian crust so deep that it damaged the internal structure irreparably, preventing a strong magnetic field from enveloping the planet. The lack of a Mars magnetosphere thereby ended any chance for a nurturing atmosphere…

Mars looks odd. Early astronomers noticed it, and today’s observatories see it every time they look at the red globe. Mars has two faces. One face (the northern hemisphere) is composed of barren plains and smooth sand dunes; the other face (the southern hemisphere) is a chaotic, jagged terrain of mountains and valleys. It would appear the crustal dichotomy formed after a massive impact early in the development of Mars, leaving the planet geologically scarred for eternity. But say if this impact went beyond pure aesthetics? What if this planet-wide impact zone represents something a lot deeper?

To understand what might have happened to Mars, we have to first look at the Earth. Our planet has a powerful magnetic field that is generated near the core. Molten iron convects, dragging free electrons with it, setting up a huge dynamo outputting the strong dipolar magnetic field. As the magnetic field threads through the planet, it projects from the surface and reaches thousands of miles into space, forming a vast bubble. This bubble is known as the magnetosphere, protecting us from the damaging solar wind and prevents our atmosphere from eroding into space. Life thrives on this blue planet because Earth has a powerful magnetic solar wind defence.

Although Mars is smaller than Earth, scientists have often been at a loss to explain why there is no Martian magnetosphere. But according to the growing armada of orbiting satellites, measurements suggest that Mars did have a global magnetic field in the past. It has been the general consensus for some time that Mars’ magnetic field disappeared when the smaller planet’s interior cooled quickly and lost its ability to keep its inner iron in a convective state. With no convection comes a loss of the dynamo effect and therefore the magnetic field (and any magnetosphere) is lost. This is often cited as the reason why Mars does not have a thick atmosphere; any atmospheric gases have been eroded into space by the solar wind.

However, there may be a better explanation as to why Mars lost its magnetism. “The evidence suggests that a giant impact early in the planet’s history could have disrupted the molten core, changing the circulation and affecting the magnetic field,” said Sabine Stanley, assistant professor of physics at the University of Toronto, one of the scientists involved in this research. “We know Mars had a magnetic field which disappeared about 4 billion years ago and that this happened around the same time that the crustal dichotomy appeared, which is a possible link to an asteroid impact.”

During Mars’ evolution before 4 billion years ago, things may have looked a lot more promising. With a strong magnetic field, Mars had a thick atmosphere, protected from the ravages of the solar wind within its own magnetosphere. But, in an instant, a huge asteroid impact could have changed the course of Martian history forever.

Mars once had a much thicker atmosphere along with standing water and a magnetic field, so it would have been a very different place to the dry barren planet we see today.” – Monica Grady, professor of planetary and space sciences at the Open University.

Losing its magnetic field after the deep asteroid impact catastrophically damaged the internal workings of the planet, Mars quickly shed its atmosphere, thereby blocking its ability to sustain life in the 4 billion years since. What a sad story

Original source: Times Online (UK)


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Hello! My name is Ian O'Neill and I've been writing for the Universe Today since December 2007. I am a solar physics doctor, but my space interests are wide-ranging. Since becoming a science writer I have been drawn to the more extreme astrophysics concepts (like black hole dynamics), high energy physics (getting excited about the LHC!) and general space colonization efforts. I am also heavily involved with the Mars Homestead project (run by the Mars Foundation), an international organization to advance our settlement concepts on Mars. I also run my own space physics blog: Astroengine.com, be sure to check it out!

Comments on this entry are closed.

  • God October 6, 2008, 9:11 AM

    Ok Ok, maybe i did… but even I have to answer to someone. Just be thankful I spared the earth.

  • marcellus October 6, 2008, 5:08 PM

    Face it folks. Mars is too tiny to have a dense atmosphere. It is just barely bigger than half the size of Earth’s diamerer (4200 miles as compared to 8000 miles).

    It probably has microbiologic life organisms on it, but that won’t be determined until we have human missions reach the planet.

    Titan can have a much thicker atmosphere because its gases can persist in a much lower temperature than Mars.

  • dollhopf October 6, 2008, 10:54 AM

    addressed to Mr. G. Bendt, who wrote:

    Mars has lost its atmosphere because its mass is tool low to hold its atmophere. Mars has only one tenth of the mass of the Earth. Shadowdancer is right with Venus. Venus has no magnetic field but a thick atmosphere, as the mass of Venus is about the same as the mass of Earth. Venus can hold its atmosphere, as does Earth.

    Dear Sir,

    after receiving the above message of yours I hoisted my sails and set out my ship for the shores of our neighbours in the habitable zone, to Venus and Mars, and then also out for the coasts of Saturn. And there for a while my Googleyzer observed that nearby island all in clouds and mist which we call Titan. It took me some time to come full circle. But now I am back and this is what I can say about it.

    Yes, Venus has nearly the mass of the earth (0.902) but the pressure at the planet’s surface is about 92 times that at Earth’s surface which is in no relation to the instance that Venus is not even as heavy as our Earth. On Titan I found a Surface pressure of 146.7 kPa. That means that the Titanian atmosphere is denser than Earth’s, with a surface pressure more than one and a half times that of our planet. But it has only 0.0225 of Earth’s mass! So Mars has 0.107 of the Earth mass. That is much more than Titan has. So why is the atmosphere on Mars not much denser than on Titan? You see that there is no easy correlation between the mass of a body and the atmosphere it is covered by. You see that field workers are more inevitable than ever!



  • GOD October 6, 2008, 11:51 AM

    Listen not to idols and false deities…

    I did it. Why? Because I wanted to.

    Sue me.

  • Igor the mad scientits October 6, 2008, 12:24 PM

    Thank’s for the article Ian!

    If Mars ever had a molten core providing the planet with a magnetic field, we could surely tell this by looking to see if any geological activity at the time formed rocks that were magnetically aligned with its north and south pole.

    A magnetic pole would only defend the planet’s life forms from Solar radiation, which is pretty deadly to most lifeforms we know of.

    Mars (as said by others as well) doesn’t have the mass to hold on to a thick atmosphere.

    I suspect at best it could make a research facility, pobbibly a small colony, but I can’t imagine anyone walking about the surface of Mars anytime soon.

    Unless we genetically modify humans to become super-inteligent-pan-dimensional beings (another reference to Douglas Adams), we might be in for a bit of a shock.

    What if we’re alone in the entire Universe! Eeek! Agraphobics run for the hills – er sorry run for the covers!

    We might be able to fold space one day and travel billions on light years, only to find life in the form of a bunch of furry blobs. That would be embarrasing, as the eyes of the entire planet are watching and our intrepid traveller introduces himself to a blob that’s totally unaware of his presence. doh!

  • dollhopf October 6, 2008, 12:36 PM

    And God Says:

    “I did it. Why? Because I wanted to.”

    Yes, GOD! That is what a good First Sergeant is characterized by.

  • dollhopf October 6, 2008, 12:44 PM

    Mars (as said by others as well) doesn’t have the mass to hold on to a thick atmosphere.


    Titan has much less mass than Mars but it’s atmosphere is denser than that of Earth. Where do we go from here?

  • gneissgirl October 6, 2008, 1:24 PM

    Nice theory. Of course it is also theorized that the earth got a pretty good whack from a Mars-sized body, creating our moon, and we still have a magnetic field, so if that happened to Mars, it must already have been pretty crystaline.

    Now, the Hellas Basin area must have been hit by something pretty big. Might also be a good place for future landing, as it probably has the thickest atmosphere. Possibly also water, from the looks of some of the side-canyons.

  • dollhopf October 7, 2008, 1:31 AM

    Notorious face-it-folks sayers! A little bit less arrogance and egocentricity could broaden you horizon.

    Dear Marcellus,

    you claim that the lower temperature on Titan allows a denser athmosphere. Why then does the much higher temperature on Venus allow a denser atmosphere, too? Your counterfactual reasoning is funny.

    And don’t tell us that Venus has a dense atmosphere, because it has nearly the mass of the Earth. It has not even the mass of the Earth (0.857), but the atmospheric mass is 93 times that of Earth’s atmosphere! And that despite a much higher temperature. How come, when there is not “a much lower temperature than Mars“?

    Compare mass and temperature of Earth, Venus, Mars and Titan! The facts don’t support your simple assumption that the density of the atmosphere is due to the mass.

    Dear Igor,

    your argumentation is just funny. LOL

    as said by others as well“.

    Since when does parroting decide on the correctness of a statement? Use your own reason and to speak in your own person!

  • Jaget October 7, 2008, 8:08 AM

    QUOTE: “I don’t think there is consensus that life will always evolve to be smart if given enough time, or that intelligence is a permanent condition.
    The dinosaurs bumbled along for millions of years on their own and (so far as we know) no civilization arose or survived that era.

    Evolution does not dictate that animals become smarter than they need to be for basic survival. The human condition could be one of the most unusual things to ever occur in this universe.”


    Or perhaps as soon as intelligent life arises, it will quickly become dominant. The hardest part in survival of intelligent life might be that the first evolutionary steps must survive long enough.

  • dollhopf October 7, 2008, 10:20 AM

    Sorry for the wrong values I used in the above comment.

    Due to solarsystem.nasa.gov the mass of Venus is about 4,868,500,000,000,000,000,000,000 kg and m_earth = 5,973,700,000,000,000,000,000,000 kg.

    So the mass of Venus would be about 0.81 times the mass of the Earth.

    Still the atmosphere of Venus is more than 90 times denser than that of our planet. So it is obvious that the lower mass of Mars can no simply be used to explain the relatively very low density of its atmosphere.

  • Imran Khan October 10, 2008, 9:28 AM

    Mars is a Hero,you agree or not. Mars has created the platform for primordial life forms on earth.You were not posting and commenting if mars was not there.It prevented many asteroid being hit directly to the earth.Some say we are martian.It would be great if we go there within a decade and make this thing clear that something was wrong four billion years ago.We are coming mars,this is what we are for brother.

  • Barry Voeten October 14, 2008, 1:34 PM

    The history of (life on) mars has been largely described by the various books of Zecharia Sitchin. The series hold an interesting theory, as several geological, astronomical, biological and simply historical events coalesce into one big story concerning:

    * how were earth, moon and the solar system formed
    * how did the humans come to earth
    * who built the face on mars and who does it represent
    * what did they do on mars
    * who built the pyramids and what are they
    * what happened on earth before the deluge
    * who were adam, eve, noah and god?

    Concerning Mars:
    Mars has been a way station on the way to the home planet called Niburu (read: neighbour). It has had a population of several hundreds to control the space stations.
    The entrance of the large planet of niburu into our solar system and a course close to mars & earth caused both the wipe-out of the atmosphere of mars and earth’s great flood (Eridu Genesis).

    My point is: astronomists should become historicist, historicist should become readers of Sumerian and the rest of us should read Sitchin.