life on Mars

**Richard87** · Nov24-09, 07:00 AM

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** · Nov24-09, 08:53 AM

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** · Nov24-09, 10:35 PM

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** · Nov24-09, 10:59 PM

Originally Posted by Richard87

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** · Nov25-09, 06:05 AM

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

**MaxwellsDemon** · Nov25-09, 11:44 AM

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!~~ · Nov25-09, 01:12 PM

Originally Posted by 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.

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** · Nov25-09, 01:26 PM

Originally Posted by 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.

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** · Nov25-09, 09:22 PM

Originally Posted by MaxwellsDemon

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** · Nov25-09, 10:42 PM

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!~~ · Nov25-09, 11:06 PM

Originally Posted by 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.

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** · Nov26-09, 12:39 AM

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** · Nov26-09, 05:30 AM

Originally Posted by 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).

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

**qraal** · Nov26-09, 06:34 AM

Originally Posted by mikelepore

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** · Nov26-09, 06:40 AM

Originally Posted by 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.

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** · Nov26-09, 09:25 AM

Originally Posted by MaxwellsDemon

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