Hello PF.I would like to get your view on the plausible scenario

  • #1
Hello PF.

I would like to get your view on the plausible scenario panspermia that might have happened from Mars to Earth. I will try to explain what I know about this scenario and please correct me if I am wrong but I am quite fascinated and a little bit disturbed that this might be the case.

Panspermia is the scenario where life on one planet is launched e.g on a asteroid seeding life on a nearby planet. There was a time called "The period of heavily bombardment in the yearly universe" where as in the name planets all over was a shooting gallery. We have found some Mars rocks that have chemistry going on which requires the presents of life it self. And that life is traceable to Mars and not to Earth.

Its possible for rocks to be "cast" away from the host planet at a certain speed, we called that; Escape velocity.

https://www.physicsforums.com/attachment.php?attachmentid=36763&stc=1&d=1309175834

For Earth that speed is about 11 km/s (sorry for using km) for an object to be launched away from the host planet up in the atmosphere and into space.

We also know that bacteria can be quite extreme and survive extreme temperatures, pressure, radiation in other words; They can survive a trip through space. The bacteria called; extremeophile is of that kind. A single cell organism but nonetheless life that could be the fundamental reason for evolution on Earth.

We know that Mars has one been a wet planet possibly with liquid water which indicate that life could thrive there. It could be that under the bombardment period those extremeophiles were launched from Mars and cast into space then "landed"(not the right word) on Earth - seeding life on Earth.

So if we found life on Mars based on DNA we should get over the fact that we are all descendants from Martians.


/WeW
 
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Answers and Replies

  • #2
Dotini
Gold Member
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Panspermia is in bad odor just now due to the scandal surrounding an injudicious NASA scientist. I'm guessing some forum members may be disinclined to discuss it for this reason.
 
  • #3
831
293


The good news is we know a BIG impact on Mars can scatter ejecta all over the inner solar system.

The bad news-- It is likely that either Mars was 'well dead' by that stage, or life had begun here already...
 
  • #4


Panspermia is in bad odor just now due to the scandal surrounding an injudicious NASA scientist. I'm guessing some forum members may be disinclined to discuss it for this reason.
I see that. I will make some research my self though, as I said I find it quite fascinating.

Good day. :)


//WeW
 
  • #5
Ryan_m_b
Staff Emeritus
Science Advisor
5,844
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I would like to get your view on the plausible scenario panspermia that might have happened from Mars to Earth...We have found some Mars rocks that have chemistry going on which requires the presents of life it self. And that life is traceable to Mars and not to Earth.
I strongly suspect that this is not correct, we do not yet have a comprehensive http://en.wikipedia.org/wiki/Abiogenesis" [Broken] was able to point to how conditions on Earth could have led to life. I am unaware of any evidence that Mars could have or did have these conditions.

There was a time called "The period of heavily bombardment in the yearly universe" where as in the name planets all over was a shooting gallery.

Its possible for rocks to be "cast" away from the host planet at a certain speed, we called that; Escape velocity.
There have been many periods of bombardment in the history of the solar systems formation, I think you are refering to the http://en.wikipedia.org/wiki/Format...olar_System#Late_Heavy_Bombardment_and_after". This did seem to stop shortly before the first evidence for life however it is important to remember that "shortly" means hundreds of millions of years and that the first evidence for life is for celled organisms, there must have been long processes before that to go from simple molecules to functioning celled organisms.

We also know that bacteria...
Before we get started on this bacteria are highly complex organisms featuring thousands of different biochemical processes. It is not accurate to compare the modern extremophile bacteria that we see to early life.

We know that Mars has one been a wet planet possibly with liquid water which indicate that life could thrive there.
Do we know this? I have yet to see any conclusive evidence that Mars was once a wet planet. In addition to this having water is not enough for life. As I have already said we do not have a thorough understanding of abiogenesis but there is much discussion on what http://en.wikipedia.org/wiki/Abiogenesis#Early_conditions" for how those conditions might give rise to life. Without an equal understanding of the conditions of Mars (and evidence that there was ever life) we cannot start searching for abiogenic explanations.

It could be that under the bombardment period those extremeophiles were launched from Mars and cast into space then "landed"(not the right word) on Earth - seeding life on Earth. So if we found life on Mars based on DNA we should get over the fact that we are all descendants from Martians.
Unlikely as DNA does not fossilise. Even if we did find some this would not be evidence that life on Mars resulted with life on Earth, the opposite could also be true. Before we start proposing panspermia hypothesis and looking for evidence we are going to have to have a far greater understanding of how life developed, otherwise we are just leading ourselves down blind alleys of speculation.
 
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  • #6
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3


Whateverworks,

If we found very basic single cell organisms on Mars and they did indeed have the same genetic markers as life on earth, then would it not be more indicative of a shared heritage rather than a direct heritage.

Occams razor would dictate any "seeding" would more likely come from a similar source.

There was a documentary I watched where someone was studying space debris and finding duplicates in chemical composition to life on earth, I am not sure how speculative or reliable this is however so you may want to look into this.

However I do find the idea quite plausable, Comets moving through gas clouds or being large enough to contain liquid water in their cores - I am not suggesting life in a physical form but the definitive chemical composition required for abiogenesis. Would be very interesting if life was so incredibly rare because it required a rocky planet with a small margin of error on physical environment to be seeded by a comet that has managed to pick up the basics of life (even if just chemical) from a gas cloud or by other means, then impact with a rocky planet and not destroy it (I am assuming we need a large comet for liquid centre cores or not to burn up and retain decent mass on impact), then for the life to go from there...

All very speculative of course but I find the idea quite interesting.

Ryan as a biologist whats the scientific consensus on how plausible is it for life to exist in space? Not cold vacuum space. But say a comet, sufficiently large to contain a liquid core and remain at a relatively stable temperature (captured orbital), correct chemical composition and enough time, do you think abiogenesis could occur?

What other requirements are there for basic life to begin? Also once life takes hold - such as single cell organisms, does it pretty much just go from there? And lastly, would you expect the chemical structure and underlying properties for all life to be the same or is there any speculation on other types of life, such as organic but without a DNA structure as we know it. I know this is all highly speculative and am in no way promoting this as a fact I just find the concept fairly interesting and not something I have ever googled :)
 
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  • #7


I strongly suspect that this is not correct, we do not yet have a comprehensive http://en.wikipedia.org/wiki/Abiogenesis" [Broken] was able to point to how conditions on Earth could have led to life. I am unaware of any evidence that Mars could have or did have these conditions.
You're probably right I am a "newbie" on this topic of astrophysics. Anyways I am pretty certain that I've read and heard a number of statements that there is evidence for those conditions. I will look it up but again you're probably right.


There have been many periods of bombardment in the history of the solar systems formation, I think you are refering to the http://en.wikipedia.org/wiki/Format...olar_System#Late_Heavy_Bombardment_and_after". This did seem to stop shortly before the first evidence for life however it is important to remember that "shortly" means hundreds of millions of years and that the first evidence for life is for celled organisms, there must have been long processes before that to go from simple molecules to functioning celled organisms.
That's correct such a complex reaction - simple molecules to functioning celled organisms would have to sustain over a long period of time. I was not aware of multiple bombardments so thank you for mention that.


Do we know this? I have yet to see any conclusive evidence that Mars was once a wet planet. In addition to this having water is not enough for life. As I have already said we do not have a thorough understanding of abiogenesis but there is much discussion on what http://en.wikipedia.org/wiki/Abiogenesis#Early_conditions" for how those conditions might give rise to life. Without an equal understanding of the conditions of Mars (and evidence that there was ever life) we cannot start searching for abiogenic explanations.
Its a theory. But a theory with some evidence that definitely would point for an wet Mars at some time. It has; dry river beds, dead volcano's, floodplains. As far as I know we have good reasons for a wet Mars - but its not in any way controvertible.


Unlikely as DNA does not fossilise. Even if we did find some this would not be evidence that life on Mars resulted with life on Earth, the opposite could also be true. Before we start proposing panspermia hypothesis and looking for evidence we are going to have to have a far greater understanding of how life developed, otherwise we are just leading ourselves down blind alleys of speculation.
I must agree with you but I am still to fascinated and curious about this subject :)

Whateverworks,

If we found very basic single cell organisms on Mars and they did indeed have the same genetic markers as life on earth, then would it not be more indicative of a shared heritage rather than a direct heritage.

Occams razor would dictate any "seeding" would more likely come from a similar source.

There was a documentary I watched where someone was studying space debris and finding duplicates in chemical composition to life on earth, I am not sure how speculative or reliable this is however so you may want to look into this.

However I do find the idea quite plausable, Comets moving through gas clouds or being large enough to contain liquid water in their cores - I am not suggesting life in a physical form but the definitive chemical composition required for abiogenesis. Would be very interesting if life was so incredibly rare because it required a rocky planet with a small margin of error on physical environment to be seeded by a comet that has managed to pick up the basics of life (even if just chemical) from a gas cloud or by other means, then impact with a rocky planet and not destroy it (I am assuming we need a large comet for liquid centre cores or not to burn up and retain decent mass on impact), then for the life to go from there...

All very speculative of course but I find the idea quite interesting.

Ryan as a biologist whats the scientific consensus on how plausible is it for life to exist in space? Not cold vacuum space. But say a comet, sufficiently large to contain a liquid core and remain at a relatively stable temperature (captured orbital), correct chemical composition and enough time, do you think abiogenesis could occur?

What other requirements are there for basic life to begin? Also once life takes hold - such as single cell organisms, does it pretty much just go from there? And lastly, would you expect the chemical structure and underlying properties for all life to be the same or is there any speculation on other types of life, such as organic but without a DNA structure as we know it. I know this is all highly speculative and am in no way promoting this as a fact I just find the concept fairly interesting and not something I have ever googled :)
All right I will do some googleing and hopefully get deeper into this subject. Do you remember what documentary it was? I might want to give it a look.

I guess for basic life to begin requires water and energy as the two most basic "ingredients". But Ryan will definitely give a better answer for all your questions.
 
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  • #8
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0


In my point of view the question on how life emerges is fundamental and would still be left unanswered if life had been transferred from mars to earth. An interesting fact if so but not shedding any new light on the emergence of living organisms per se. By the way I agree with cosmo novice on seeding to be more probable and meaningful from a shared source. But no "theory on seeding" from space can (from what we know right now) be remotely plausible compared to emergence of life on earth and much more difficult to research. So dig where you stand.
 
  • #9
Ryan_m_b
Staff Emeritus
Science Advisor
5,844
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Ryan as a biologist whats the scientific consensus on how plausible is it for life to exist in space? Not cold vacuum space. But say a comet, sufficiently large to contain a liquid core and remain at a relatively stable temperature (captured orbital), correct chemical composition and enough time, do you think abiogenesis could occur?
Sorry for the slow reply, the notification for this slipped under my radar. As far as I am aware there is no consensus, probably because astrobiology and abiogenesis are both quite young fields. However a brief search on Web of Science shows that there is some interesting research going on looking at http://apps.isiknowledge.com/full_record.do?product=WOS&search_mode=Refine&qid=2&SID=W1fn7phPm5F7lBECJ6c&page=1&doc=8&cacheurlFromRightClick=no" [Broken].

Some interesting ideas and discoveries but unfortunately there's too little data and understanding of abiogenesis to draw firm conclusions.
 
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