Is there evidence to support past life on Mars?

[Richard87]

Is there or was there any life on Mars in the past? Do you think so? I personally don't. I think that martian meteorite got contaminated with Earth life.

 

[gabrielh]

Possibly. We don't know much about Mars' past, so there may have been water and different atmospheric qualities some time ago. However, it looks unlikey that there'd be any advanced or sophisticated life on Mars, unless they are underground or something of that nature. Any life we find now would be along the lines of bacteria and the like.

 

[Chronos]

The famous Mars meteorite contained fossil evidence of possible microbial life forms, so contamination is not an issue. See
http://nssdc.gsfc.nasa.gov/planetary/marslife.html
for discussion.

 

[DaveC426913]

I think that martian meteorite got contaminated with Earth life.

As Chronos' link states, the structures were fossilized before the rock left Mars.

So, the fossilized ovoid structures are Martian in origin. The only question left to answer is whether the ovoids are compelling evidence of biological action, or if they are formed by some non-life process.

 

[Richard87]

Some would say that not only was there life on Mars in the distant past, but it is where Earth's life originated.

 

[MaxwellsDemon]

I think it unlikely that there was or is life on Mars. I suspect that Earth has some unique geologic processes like plate tectonics that help generate a life favorable chemical environment. I'm also thinking that our moon has helped to provide long term stability to our climate through gravitational activity. This sort of stability is necessary for life to flourish. Another thing that raises doubts about Martian life in my mind is the fact that life tends to change and effect its environment in a noticable way. Our atmospheric composition would undoubtedly be more like that of Venus (or Mars) if it weren't for the life here constantly spewing out oxygen and nitrogen. I don't see any signs of complex chemistry on Mars that would point toward the existence of life there.

 

[Sorry!]

I think it unlikely that there was or is life on Mars. I suspect that Earth has some unique geologic processes like plate tectonics that help generate a life favorable chemical environment. I'm also thinking that our moon has helped to provide long term stability to our climate through gravitational activity. This sort of stability is necessary for life to flourish. Another thing that raises doubts about Martian life in my mind is the fact that life tends to change and effect its environment in a noticable way. Our atmospheric composition would undoubtedly be more like that of Venus (or Mars) if it weren't for the life here constantly spewing out oxygen and nitrogen. I don't see any signs of complex chemistry on Mars that would point toward the existence of life there.

This is of course assuming all life in the Universe will be formed the same way on Earth, it assumes that people claim that Mars had abundant life on it, and that this life stuck around for a long enough time to make a noticeable difference to the planets atmosphere. For instance here on Earth for oxygen levels to rise enough to support any animals it took 1 billion years.

Earth has definitely been very lucky that this life flourished, I would however not rule out that life formed in other parts of even our solar system but never got a chance to really 'kick off' before being destroyed by the planet itself(especially on Mars, as far as I know the planet is very hostile) or maybe a comet/asteroid...

 

[DaveC426913]

I think it unlikely that there was or is life on Mars. I suspect that Earth has some unique geologic processes like plate tectonics that help generate a life favorable chemical environment. I'm also thinking that our moon has helped to provide long term stability to our climate through gravitational activity. This sort of stability is necessary for life to flourish. Another thing that raises doubts about Martian life in my mind is the fact that life tends to change and effect its environment in a noticable way. Our atmospheric composition would undoubtedly be more like that of Venus (or Mars) if it weren't for the life here constantly spewing out oxygen and nitrogen. I don't see any signs of complex chemistry on Mars that would point toward the existence of life there.

Don't discount microbial life so quickly. It's surely true that so macrofauna have developed on Mars but Mars' environment is well-within the comfort zone of microbial life.

 

[ehilge]

I'm also thinking that our moon has helped to provide long term stability to our climate through gravitational activity. This sort of stability is necessary for life to flourish.

I realize that this is a little off topic, but could you explain the moon helps stabilize long term climate stability?

And for the record, I certainly think that Mars supported life at some point in the past. As mentioned, even if the conditions on Mars aren't what we're used to life could still develop. Just look at some of the conditions where life is found in Earth like in heat vents and what not. Finally, even if the meteorite is somehow proved to be from non-biological processes, that certainly doesn't mean that life never existed anywhere on Mars.

 

[MaxwellsDemon]

What I meant by the moon stabilizing the climate, is that without the moon our planet would wobble about its axis of rotation a lot more than it does over long periods of time (millions of years). Currently we go through periods of ice ages and warmth that cycle on and off due to the Earth's wobble, but without the moon our wobble would be more erratic...so ice ages would be more frequent and more severe. Abrupt and severe environmental change is bad if you're an evolving life form. To form complex life you want a changing environment, but not one with too much change. We owe our relatively stable global climate to the presence of our comparatively large moon. Mars' tiny little moons don't have the same stabilizing effect, so I'd imagine that the somewhat unstable long term climate would be an obstacle for Martian life. I grant that microbial life might exist, but still I think the lack of any geologically inexplicable global chemicals (like our atmospheric oxygen) is a strong sign that there probably isn't any life there...I think that by its very nature life tends to notably mark and change its environment. The presence of something like oxygen...or even significant quantities of methane...would tip me off that there is possibly something biologically interesting happening there. As far as bodies in the Solar System go, I think Titan is probably the best candidate for life. Some of those geologically active moons with water are also strong candidates. Although its true that life on Earth didn't cause appreciable oxygen levels early in its development, methane was thought to be an indicator of early life on Earth...I remember hearing a lecture by a biology professor who pointed out geologic evidence of methane in rocks dating back to around 3 and a half billion years ago. He took this as evidence of early life. (I asked him whether it might be due instead to atmospheric chemistry...he thought not) I agree with you all that microbial life is unbelievably durable so I'm willing to admit that Martian microbes aren't outside the realm of possibility.

 

[Sorry!]

What I meant by the moon stabilizing the climate, is that without the moon our planet would wobble about its axis of rotation a lot more than it does over long periods of time (millions of years). Currently we go through periods of ice ages and warmth that cycle on and off due to the Earth's wobble, but without the moon our wobble would be more erratic...so ice ages would be more frequent and more severe. Abrupt and severe environmental change is bad if you're an evolving life form. To form complex life you want a changing environment, but not one with too much change. We owe our relatively stable global climate to the presence of our comparatively large moon. Mars' tiny little moons don't have the same stabilizing effect, so I'd imagine that the somewhat unstable long term climate would be an obstacle for Martian life. I grant that microbial life might exist, but still I think the lack of any geologically inexplicable global chemicals (like our atmospheric oxygen) is a strong sign that there probably isn't any life there...I think that by its very nature life tends to notably mark and change its environment. The presence of something like oxygen...or even significant quantities of methane...would tip me off that there is possibly something biologically interesting happening there. As far as bodies in the Solar System go, I think Titan is probably the best candidate for life. Some of those geologically active moons with water are also strong candidates. Although its true that life on Earth didn't cause appreciable oxygen levels early in its development, methane was thought to be an indicator of early life on Earth...I remember hearing a lecture by a biology professor who pointed out geologic evidence of methane in rocks dating back to around 3 and a half billion years ago. He took this as evidence of early life. (I asked him whether it might be due instead to atmospheric chemistry...he thought not) I agree with you all that microbial life is unbelievably durable so I'm willing to admit that Martian microbes aren't outside the realm of possibility.

Hmm I'm not to sure that's correct. I know that the Earths axial rotation is effected by the moon, but I never kenw the actual orbit of the Earth around the sun was (which causes major climate changes like you spoke of)

However no significant climate changes are associated with extreme axial tilts

http://en.wikipedia.org/wiki/Milankovitch_cycles

 

[Chronos]

The problem with life without the moon is the wobble factor creates a very unstable climate. Life needs a long term stable climate to thrive at any given location on earth.

 

[mikelepore]

What I meant by the moon stabilizing the climate, is that without the moon our planet would wobble about its axis of rotation a lot more than it does over long periods of time (millions of years).

The period of the wobble is about 64,000 years.

 

[qraal]

The period of the wobble is about 64,000 years.

That's the cyclical component, but the long term behaviour of an Earth without a Moon is chaotic and non-periodic.

However I'm not convinced that such a planet would be all that dramatic in its effects on biogeography.

 

[qraal]

I think it unlikely that there was or is life on Mars. I suspect that Earth has some unique geologic processes like plate tectonics that help generate a life favorable chemical environment.

Plate tectonics kicked in long after Life got started. However tidal action might be vital to pre-life chemistry - most RNA generating scenarios require a cyclical process to change the chemical mix. Tides would do the job perfectly. A proto-Venus would've experienced solar tides big enough to do the job, if it rotated a lot quicker than today. But a proto-Mars would've experienced much weaker tides than Earth.

I'm also thinking that our moon has helped to provide long term stability to our climate through gravitational activity. This sort of stability is necessary for life to flourish.

Mars doesn't have any geographic barriers to life migrating to follow its preferred weather, unlike an Earth-like planet with a lot of oceans.

Another thing that raises doubts about Martian life in my mind is the fact that life tends to change and effect its environment in a noticable way. Our atmospheric composition would undoubtedly be more like that of Venus (or Mars) if it weren't for the life here constantly spewing out oxygen and nitrogen. I don't see any signs of complex chemistry on Mars that would point toward the existence of life there.

In that respect I reluctantly agree. But there might be subterranean refugia even today. Mars was once habitable, but has been in terminal decline the last 3 aeons.

 

[Garth]

I don't see any signs of complex chemistry on Mars that would point toward the existence of life there.

Martian Methane Reveals the Red Planet is not a Dead Planet ?

Garth

 

[Ich]

"...in either a biologic or geologic sense"

 

[MaxwellsDemon]

Interesting link...Martian methane definitely makes life at least seem more plausable in my mind.

 

[Garth]

There is also this old chestnut raising its head again: Evidence of life on Mars lurks beneath surface of meteorite, Nasa experts claim. (27 Nov 2009)

Garth

 

[DaveC426913]

There is also this old chestnut raising its head again: Evidence of life on Mars lurks beneath surface of meteorite, Nasa experts claim. (27 Nov 2009)

Garth

Hee! Precious!

Gary Nelson wrote:
The fact that they found rocks with the same chemical comp. that Mars does, doesn't mean that that is where they came from. We now know that the universe is teeming with planets and It could have come from someplace else (mabey).

Life in a rock from Mars is sooo unlikely. It's 50 million km away for Pete's sake. Much more likely that it came from OGLE-05-390Lb, a mere 200 million billion km away...

 

[Sorry!]

Wow, they knew about this meteor before I was even born, lol. Weird how they still are 'unsure' if life at some point lived on Mars... I thought that the rovers that went to the planet last time were equiped with tools to dig into the ground to take samples? Are they not equiped with proper tools to study the existence of fossils?
This would seem quite odd to me considering the meteor...

What about taking say a larger chunk of martian rock (say from inside a cave or a recent meteor impact) and having a rocket launch it back to Earth. Is this possible or even feasible?

 

[MaxwellsDemon]

What about taking say a larger chunk of martian rock (say from inside a cave or a recent meteor impact) and having a rocket launch it back to Earth. Is this possible or even feasible?

Its possible to do that, but it would be incredibly expensive. The whole idea behind these rover missions is to keep expenses down by sending lots of tiny relatively crappy robots instead of mounting one really expensive mission. NASA has problems getting the funding it needs from our government...they'd rather spend it on things like wars where they look for non existent weapons of mass destruction.

 

[Stark]

Considering the amount of water on Earth, compared to that of Mars and considering how long it took for Earth to develop life, I'm surprised anyone even considers it.

 

[DaveC426913]

Considering the amount of water on Earth, compared to that of Mars and considering how long it took for Earth to develop life, I'm surprised anyone even considers it.

Mars has evidence that very large volumes of water once freely flowed on its surface until relatively recently. How much water and time do you think life needs?

 

[ideasrule]

It took a long time for Earth to develop life? There are fossilized bacterial mats 3.8 billion years old. Earth is only 4.5 billion years old.

 

[Count Iblis]

Life also somehow survived the Late Heavy Bombardment that ended 3.8 billion years ago:

http://en.wikipedia.org/wiki/Late_Heavy_Bombardment

Three-dimensional computer models developed in May 2009 by a team at the University of Colorado at Boulder postulate that much of Earth's crust, and the microbes living in it, could have survived the Bombardment. Their models suggest that although the surface of the Earth would have been sterilized, hydrothermal vents below the Earth's surface could have incubated life by providing a sanctuary for heat-loving microbes.[12]

 

[Sorry!]

I think what the poster meant to say was how long it took for 'complex-life' to form. I believe he is under the impression that people believe complex life at the level of what came to Earth (That is to say animals).

It did take a very long time to develop animals approximately what, 3 billion years? Just to get to multicellular it took around 2.5 billion...

This obviously does not mean that life never existed on Mars, or doesn't currently live there.

 

[Chronos]

Life arose on Earth almost immediately after it became habitable, as count noted.

 

[qraal]

Life arose on Earth almost immediately after it became habitable, as count noted.

Animal life came along much, much later. Micro & Macrofossils from animals only appeared c.600 Mya, some 4 billion years after Earth formed and 3.2 billion after the LHB finished. So while bacteria/archea seem to have a deep history, metazoans are Johnny-Come-Latelys. Just why they came along so late is disputed, but I wouldn't be surprised if there's an astrophysical connection for the timing.

 

[DaveC426913]

Life arose on Earth almost immediately after it became habitable, as count noted.

I'm not sure about "almost immediately". 4.5 / .7 is > 15%.

That's almost 1/6th of its age spent lifeless.

 

[Sorry!]

I'm not sure about "almost immediately". 4.5 / .7 is > 15%.

That's almost 1/6th of its age spent lifeless.

It's important to note that the Earth had life as soon as it became habitable. Not as soon as it was formed.