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

Was Life on Mars Extinguished Prematurely by a Huge Impact?

5 Oct , 2008 by

[/caption]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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reevesAstronomy
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reevesAstronomy
October 5, 2008 7:20 AM

In the long term, adding gases to the atmosphere is something humans are really good at, just look at all the greenhouse gases we’re emitting right now! Light gases will just float away from Mars, what if we output lots of heavy gases? The air doesn’t necessarily need to be breathable, but it’d be nice to have decent temperatures and a higher atmospheric pressure so you don’t get the bends if you need to step outside without a space suit on.

Curry
Guest
Curry
October 5, 2008 12:30 AM

Very interesting read. Can you imagine if that event is responsible for preventing the evolution of life on Mars? ie. We would have neighbors on a habitable planet next door if that impact didn’t happen – an amazing thought.

Rey
Guest
Rey
October 5, 2008 1:04 AM

…there can only be one grin

leafguy
Member
October 5, 2008 2:26 AM

Perhaps the impact on mars ejected a piece of rock that hit the earth and triggered the start of life 3.9 billion years ago.

If this event supposedly hit around 4 billion years ago, one can’t rule out that the earliest microbes supposed appeared on earth around 3.9 – 4.3 billion years ago depending on the estimates. Just some food for thought smile

Neil
Guest
Neil
October 5, 2008 4:20 AM

wouldnt it be nice to go back in time and save mars from being hit, wouldnt it be great to have a neighbouring planet to visit, only problem is above above poster speculated we may not exist to appreicate it

the mind boggles

damian
Member
October 5, 2008 5:03 AM

Perhaps one day we will have the means to re-start the molten core on Mars. Give it back a magnetosphere. Now thats what I would call terraforming. smile

Hunnter
Member
Hunnter
October 5, 2008 5:26 AM
T’is a shame ol’ Mars died off. Twas taken from us too young. On the subject of terraforming, it would be a really hard job. Unlike Spore where you just point and click, this would require a LOT of energy. Some ideas could be to create a massive mirror that sits on the dark side to reflect sun on the whole planet, 24/… uh wait, that phrase won’t work with Mars.. haha, but you know what i mean. Then you would probably need to add lots of gas, specifically gases that retain heat, such as CO2. (anyone know of Jupiter has much of that? Or Saturn?) Then you’d pretty much just need to wait for awhile to let… Read more »
Roger Levinson.
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Roger Levinson.
October 5, 2008 6:01 AM

What a sad story, but maybe this is why the planet we know as Mars has sent a message to brother Earth and requested our planet to send life forms to revive Mars. Maybe this messge is being sent to Earth from extra solar planets around the galaxy for similar help. Maybe this is the reason as to why we are here. Roger

some dumb kid
Guest
some dumb kid
October 5, 2008 7:37 AM

martians we hardly knew ye

George Kountouris
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George Kountouris
October 5, 2008 7:45 AM

The possibilities for the apparent to this article are high. We need detailed geological research by the presence of manned missions there for more evidences

Bunnyman
Guest
October 5, 2008 7:52 AM

Great article, this makes me think that life in the universe may be a matter of luck as well as having the right conditions. Between the comets, asteroids and meteors alone it seems there are plenty of opportunities to extinguish nascent life. The several mass extinctions on our own planet show how perilously close Terran life came to be snuffed out in the past.

Maxwell
Member
Maxwell
October 5, 2008 7:56 AM

I don’t think its that hard to imagine mars, alive.
Its something we suspected (or rather, expected) up until the mariner probes showed otherwise.

I wonder if our space exploration history would have been different if there was a habitable world filled with animals nearby… or if we would have been the ones being explored by martians.

I think terraforming mars is still possible given what we know. If you believe in man made global warming (accidentally changing the climate) then you must admit that change through intentional efforts are not that far fetched.
The more difficult thing would be figuring out how to spin up a magnetic field, to make our changes permanent.

Grinspoon
Guest
Grinspoon
October 5, 2008 8:30 AM
I always wonder though, was everything on earth just right and the conditions here are exactly what’s needed, or is it just the conditions life had to evolve in, and life will tend to find a way and quite different to what we know. Also, the lack of a Martian magnetosphere, thats just due to the internal workings being static and the make up of the core. Isn’t it just a likely being a small planet further from the sun, it just all died out, not enough radioactive material? If a huge impact killed the planet, it was obviously still geographically active for a very time after to cover it up, and to have supported water after. So… Read more »
leafguy
Member
October 5, 2008 8:52 AM

Ummm, in regards to the posters of terraforming. It is almost impossible to terraform mars because of the lack of a magnetic field. Nothing to stop the solar win from swiping away the atmosphere

Curtis
Guest
Curtis
October 5, 2008 8:59 AM
Great variation of commentary. With the timelines involved, I can’t help but speculate that our inner Solar system was perhaps influenced by the same event. First Venus rotates on it’s axis in the opposite direction to the other planets, except Uranus, of Course. I have seen theories that Venus had a Massive Impact Event that essentially “flipped” the planet upsidedown. Earth’s Moon was created when a massive object Collided with earth. Scientists consider the impact to be a Glancing Blow, similar to Billiards, when you “cut” the ball. The Theory says that after that blow, the resulting ejecta formed our moon. This explains how our Moon is actually Spiraling away from us, rather than orbiting. So let’s say… Read more »
Jim Baerg
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Jim Baerg
October 5, 2008 9:45 AM

I don’t see why anyone takes seriously the idea that a magnetic field is important for preserving a thick atmosphere.

After all Venus has no magnetic field but as a much thicker atmosphere than earth, including a few times as much nitrogen as earth as well as the enormous amounts of CO2

Frank Glover
Guest
Frank Glover
October 5, 2008 10:23 AM

…In addition to being closer to the Sun, where one would expect the solar wind to be yet more intense.

Thanks, Jim. That seeming contradiction’s bugged me for a long time, too….

If Mars had been at least as massive as Venus (with the Earth-like rotation it already has), I suspect things would’ve been rather different there today as well.

SkepticTim
Member
SkepticTim
October 5, 2008 10:28 AM

The asymmetry between the Martian hemispheres is somewhat reminiscent of the asymmetry between the near and far sides of the moon. In both cases major asteroid impacts have been postulated as the origin of this asymmetry. Significant mascons, evidenced from lunar gravimetric data, have been interpreted as evidence of the collision. If a large asteroid collision with mars was sufficiently catastrophic to disrupt the Martian core and prevent its reformation, then I would expect to see similar gravimetric evidence of mascons on mars. However, the very limited gravimetric data that I have seen to date does not seem to contain much evidence of Martian mascons. Has anyone seen such evidence?

Morellio
Member
Morellio
October 5, 2008 2:54 PM

How do you find remnants of 4 billion year old life?

Space Cookie
Guest
Space Cookie
October 5, 2008 3:15 PM

How do you find remnants of 4 billion year old life?
You look for it.

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