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Richard87
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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.
As Chronos' link states, the structures were fossilized before the rock left Mars.Richard87 said:I think that martian meteorite got contaminated with Earth life.
MaxwellsDemon said: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.MaxwellsDemon said: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.
MaxwellsDemon said: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.
MaxwellsDemon said: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.
http://en.wikipedia.org/wiki/Milankovitch_cyclesHowever no significant climate changes are associated with extreme axial tilts
MaxwellsDemon said: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).
mikelepore said:The period of the wobble is about 64,000 years.
MaxwellsDemon said: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.
MaxwellsDemon said:I don't see any signs of complex chemistry on Mars that would point toward the existence of life there.
Garth said: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
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...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).
Sorry! said: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?
Stark said: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.
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]
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.Chronos said: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%.Chronos said:Life arose on Earth almost immediately after it became habitable, as count noted.
DaveC426913 said:I'm not sure about "almost immediately". 4.5 / .7 is > 15%.
That's almost 1/6th of its age spent lifeless.
There are several pieces of evidence that suggest the possibility of life on Mars. For instance, the presence of water on the planet's surface and in its past geological history, the discovery of organic molecules, and the potential for underground habitats are all factors that support the idea of microbial life on Mars.
Scientists plan to explore the possibility of life on Mars through various methods, including robotic missions, sample return missions, and human exploration. These missions will involve studying the planet's atmosphere, surface, and subsurface, as well as collecting and analyzing samples for any signs of life.
One of the main challenges scientists face when exploring the possibility of life on Mars is the harsh environment of the planet. Mars has a thin atmosphere, extreme temperatures, and high levels of radiation, making it difficult for any potential life forms to survive. Additionally, the vastness of the planet and the limited resources and technology available for exploration also pose challenges.
Studying Mars can help us understand the potential for life on other planets by providing insights into the conditions necessary for life to exist. By studying the planet's geology, atmosphere, and potential habitats, we can gain a better understanding of how life may have evolved on Mars and how it could potentially exist on other planets.
Some potential ethical considerations when exploring the possibility of life on Mars include the risk of contaminating the planet with Earth microbes, the impact of human exploration on any potential native life forms, and the responsibility to preserve and protect any potential life that may be discovered on Mars. There is also a debate about whether it is ethical to alter the environment of another planet for human purposes.