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iblis
admirer of the sky
Reged: 07/12/06
Posts: 2243
Loc: Germany
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it is often cited as the reason why Mars does not have a thick atmosphere and any atmospheric gases have been eroded into space by the solar wind:
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
The lack of a Mars magnetosphere thereby ended any chance for a nurturing atmosphere…
but 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.
read here:
http://www.timesonline.co.uk/tol/news/uk/science/article4882708.ece
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Grüße von Iblis
The Universe is not only queerer than we imagine; it is queerer than we CAN imagine.
(Haldane)
and here I observe that universe
The sky is my heaven !**********  ********
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Rick Woods
Post Laureate
Reged: 01/27/05
Posts: 4318
Loc: Inner Solar System
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Well, there's certainly a huge basin in the northern hemisphere that would fit the description!
But I'd stop short of saying there's no life on Mars. Life adapts, evolves; there's no reason it couldn't adapt quite comfortably to current conditions on Mars. Maybe not life as we know it, but life.
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- Rick
14" LX200GPS
8" Meade 826C
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llanitedave
Humble Megalomaniac
Reged: 09/26/05
Posts: 10489
Loc: Amargosa Valley, NV, USA
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A huge collision would have disrupted Mars' magnetic field, but not necessarily destroyed it. It might even be argued that the injection of so much energy into the planet caused substantial reheating, and may have delayed by some small amount of time the freezing out of Mars' internal dynamo.
During eras when the Earth's magnetic field is undergoing a reversal, there is usually some period of time, possibly millenia, during which the Earth for all practical purposes has no global field, and magnetic lines of force are chaotic and disorderly. But they are still there, and they still provide protection against impinging ions. There are no mass extinctions known for any of the Earth's recorded magnetic reversals. So the lack of a global magnetic field by itself is not a reason for life not to exist. Even today, with no substantial field on Mars, any organisms that evolved to live in the deep crust could survive there quite nicely. They'd be hard to find with today's technology, but at some point they might be.
All that said, I'm not sanguine about the possibility of life on Mars. I'm not discounting it, but I think it's more likely than not to be absent. I hope I'm wrong.
My reasoning is based not on what existing life is able to adapt to but on how life develops originally from nonlife. I suspect it may be rather less easy than many others do, and it likely relies on a number of fortuitous circumstances that may not always be repeatable. It's harder for life to originate in an environment than it is for it to evolve into an environment once it already is present. The more complex and diverse the available, interacting environments, the more likely it is that the early proto-living molecules will cross some particular threshhold to becoming actual organisms. I suspect that Mars has always had a lower diversity of chemical environments than Earth, and with fewer opportunities for them to exchange materials and energy, and what did exist lasted for a shorter period of time. That reduces the likelihood that life ever appeared there.
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"S.O.E." (Sauron's Other Eye) 16" Royce conical mirror: A permanent work in progress.
10" Homebuilt dob, old Coulter mirror
Next Project: The "Eye of Sauron" Observatory!
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Rick Woods
Post Laureate
Reged: 01/27/05
Posts: 4318
Loc: Inner Solar System
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I hope you're wrong too, Dave!
(Remember, the Procto creatures of Goboon Seven look like harmless rocks - until they attack!)
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- Rick
14" LX200GPS
8" Meade 826C
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Pess
(Title)
Reged: 09/12/07
Posts: 1910
Loc: Toledo, Ohio
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Quote:
That reduces the likelihood that life ever appeared there.
Life arose on Mars via two possibilities: Abiogenesis or migration from outer space.
Earth is 4.5 billion years old and we have identified fossils 3.5 billion years old. Since earth undergoes so much resurfacing via tectonic activity we can safely assume that life probably goes back a lot further than what we find fossils for.
So with that assumption we can figure that life arises pretty quick under the right conditions either by self-assembly or by spores hitching rides on space debris.
Earth and mars certainly share a similar adolescence and, certainly, at one time mars had a magnetic field.
So it makes more sense than not that life got a foothold at earlier age. Life certainly faced challenges as the planet dried, lost its magnetic field and let its hydrogen & oxygen evaporate off into space.
But I think life is pretty tenacious and if it got a foothold there is likely some niches where it continues to hold on if not thrive.
I suspect if we dig down deep enough we'll find some water and, likely, a mat of biologic material.
Pesse (shrugs) Msit
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Lusty
super member
Reged: 08/24/08
Posts: 193
Loc: Florida USA
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Why, I thought life was on Mars. I saw the movie, "Mars Attacks."
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Rick Woods
Post Laureate
Reged: 01/27/05
Posts: 4318
Loc: Inner Solar System
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Beautiful red Princesses and giant green Tharks.
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- Rick
14" LX200GPS
8" Meade 826C
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Pess
(Title)
Reged: 09/12/07
Posts: 1910
Loc: Toledo, Ohio
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Pesse (There is no life on mars since they closed the Hard Rock Cafe franchise there.) Mist
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