Perhaps Shaun Barrett - is RIGHT! :-)

BWhite · 2005-02-18 16:29:44

Bill:-
But my instincts remain that =IF= living microbes exist today on Mars they are the resilient survivors of a once flourishing planet engulfing biosphere, which perhaps flourished and 99.99% died off before life arrived on Earth. A billion years ago.
Forgive me if I seem obtuse but I'm uncertain how to interpret your meaning here, Bill.
You appear to be saying that the hypothetically flourishing Martian biota we're speculating about could have largely died out maybe a billion years ago, possibly leaving isolated bacterial remnants underground. And it looks like you're placing the 'arrival' of life on Earth at some time close to, but perhaps slightly after, that event.
Am I on the right track or have I got it all wrong?

More or less. . .

I believe that both the diversity and abundance of life is the "natural" state if sufficient resources exist.

My intuition is that any living microbes on Mars are (a) survivors of a once thriving and abundant Marsian Gaia or (b) descendants of some poor hapless Terran microbes sent for a ride on an asteroid.

(a) more likely than (b)

=IF= a thriving Marsian Gaia existed "before" life on Earth then we need to take more seriously the idea that Terran life was seeded from Mars although a "second Genesis" would actually be far more interesting from a philosophic point of view.

= = =

This http://www1.nasa.gov/home/hqnews/2005/f … .html]NASA press release calls claims of Mars life "false" - - to a llawyer, the assertion that a claim is "false" implies willful deceit, not merely a mistake or difference of opinion. I cannot tell whether that is what NASA means to say.

Shaun Barrett · 2005-02-18 20:23:16

Thanks, Cindy, for bringing that recent 'correction' from NASA to our notice. Presumably, the report was filed by an over-enthusiastic journalist who pounced on half-baked second-hand information and took it all too seriously.
[Or NASA, scared witless that its long-standing cover-up about life on Mars was about to be blown wide open, got hold of poor Dr. Carol Stoker and put the silencers on her. You know, the old story: "Nice little retainer you get from NASA, eh Carol? And a nice little family you have at home, too. It'd be a pity to see any harm come to all of that, wouldn't it?!"
:laugh: Just like all those conspiracies you see in the movies!!]

Thanks, too, Bill for clarifying your opinions about hypothetical Martian life. In our present state of ignorance, of course, almost any version of the sequence of events on early Mars is as valid as any other.
The sequence of events on Earth, though, is somewhat better understood because we have access to more evidence. This is why my attention was drawn to your comment about life appearing on Earth a billion years ago.
As I understand it, there is good evidence for bacterial life on Earth about 3.4 billion years ago. The solid evidence is presented in http://www.cnn.com/TECH/space/9909/03/s … .html]THIS ARTICLE, and consists of an actual fossil of the physical form of the bacterial colony; the remains of which are recognized as stromatolites.

(Quote:) The 1.25 meter, "egg carton" shaped rock, retrieved from the remote Australian outback in July[1999], contains life forms believed to be 3.46 billion years old.
"They were the earliest life forms and probably the only form of life on Earth for the best part of two billion years," said Dr. Kath Grey of Macquarie University in New South Wales, a member of the team that discovered the fossil. (Unquote.)

But other evidence has helped to push the date for the earliest bacterial life on Earth back to maybe 3.85 billion years. (Though it's important to emphasize that the data are still disputed in some quarters and the conclusions are therefore still, technically, equivocal. It should be noted also that this applies even to the above stromatolite evidence from 3.46 billion years ago, too, although the majority of scientists accept it as fact.)
There are two articles which, I think, give a good account of this evidence. One of them is from 1998 and the second, which presents data tending to bolster the first, is from just last month:-
http://www.x-tronix.com/applic5.htm]Article 1
http://rednova.com/news/display/?id=122138]Article 2

Although it's difficult to state categorically just when life appeared here on Earth, because there's always room for the data to be questioned, my reading on the subject indicates that the majority of researchers are reasonably satisfied that bacterial life, much as we know it today, existed here 3.8 billion years ago. The inference is drawn that more primitive living precursors to that life were probably in existence at about 4 billion years ago.
Interestingly, this period of Earth's history lies just prior to the end of what is called the 'Late Heavy Bombardment' of our Moon, which ended at 3.8 billion years ago, a bombardment assumed to have affected Earth just as much as it did Luna. And yet, it appears the bombardment didn't extinguish life here - an indication of how fiercely tenacious life really is once it gets a grip somewhere.

If we assume that the purported traces of biogenic material in the Martian meteorite ALH 840001 are actually of biological origin, then Dr. McKay's suggestion that Mars may have become more conducive to the development of life, sooner than Earth did, starts to look more plausible. From memory, ALH 840001 is some 4.5 billion years old and seems to be telling us that life appeared on Mars very quickly after the planet formed.
If all this is true, a big if (! ), then it looks more likely that life originated on Mars first, before being propagated by impact transfer to Earth.

But, Bill, the main point of my post (amid cries of "My God! Don't tell me he's actually getting to the point, at last!! ) is to address your apparent belief that life on Earth is only about 1 billion years old.
I don't think there is any reasonable evidence to support this notion, while there's a great deal of evidence which seems to refute it. Certainly, as far as I can tell, there's no serious doubt at all that complex cellular life was flourishing here at least 2.7 billion years ago.
If you are aware of all this already, then I apologise for the needless repetition. But then it begs the question - if you know all this, what leads you to the conclusion terrestrial life is only 1 billion years old?

dickbill · 2005-02-18 23:03:20

About the methane in Mars atmosphere, it has been said that it could have 2 origins, bio or volvano.
The latest eruptions or lava flow on Olympus Mons have been dated at about 10 million years (with the impact craters counting method, said Hartmann in his "Traveler's guide to Mars" ), so It's very well possible that Olympus Mons still holds some pockets of hot magma that leak some gas from time to time.
But since hot springs are also a hot spot for thermophilic lifeforms, maybe the bio and volcanic explanation could overlap here. Maybe the carbon isotopic ratio C12/C13 could help to differentiate between the two (on Earth the biogenic carbon is enriched 20 to 30% in carbon 12 verus C13). So if this CH4 is biogenic, the isotopic ratio of carbon and hydrogen might help to know. it's a bit too far for the rovers to go in these regions but they seem unfatiguable. Maybe in 3 or 4 years they will be still there and find a fossilized hot spring with tiny rod shaped mineral in chains !

BWhite · 2005-02-18 23:03:38

But then it begs the question - if you know all this, what leads you to the conclusion terrestrial life is only 1 billion years old?

I did not mean to suggest this.

A Marsian Gaia would have gone extinct (but for scattered survivors like deep underground bacteria) at least one billion years ago, perhaps more.

= = =

Thinking about it more I now concede I cannot offer an opinion on whether Mars life crossed over to Earth; Earth life crossed over to Mars (asteroid hitchhiking) or there was perhaps independent genesis - - if there actually is any Mars life whatsoever.

Once again, only by going can we answer these questions.

= = =

Tonight, MSNBC had an article which appears to suggest that any report that NASA believes the methane signatures area strong evidence of life are inaccurate, perhaps even false as NASA denies they are persuaded by the current evidence.

However, the article suggested that the individual NASA employed scientists - - in their personal opinion - - stand by the original report.

Shaun Barrett · 2005-02-19 07:57:47

Bill:-

I did not mean to suggest this.

Ah, I see. I misinterpreted your initial comment and you misinterpreted my attempt to avoid misinterpretation. :laugh:

Bill again:-

Tonight, MSNBC had an article which appears to suggest that any report that NASA believes the methane signatures are strong evidence of life are inaccurate, perhaps even false as NASA denies they are persuaded by the current evidence.
However, the article suggested that the individual NASA employed scientists - - in their personal opinion - - stand by the original report.

Ah, I see. The individual NASA scientists have interpreted the data in a way that NASA believes is, in fact, a misinterpretation .. unless I've misinterpreted something.

[At least we've still got the report to look forward to .. er, um .. I think.]

dickbill · 2005-02-19 09:24:15

However, the article suggested that the individual NASA employed scientists - - in their personal opinion - - stand by the original report

In space daily the article title was thast "NASA scientists say that Mars may have life" or something similar, but I rmember the "may" because I checked twice. Nothing wrong with that or to redraw.
"may" is fine in the context of Viking experiments, abundant past liquid water and methane in the mars atmosphere.

BWhite · 2005-02-21 14:51:16

http://www.space.com/scienceastronomy/m … 17.html]An ancient Gaia?

It's more plausible now:

Water was common across a vast region of ancient Mars, creating habitable conditions for long stretches of time billions of years ago, scientists said Thursday.
New data reveal water in the Meridiani Planum region of Mars extended across hundreds of thousands of square miles, at least as groundwater and possibly as shallow lakes or seas.
The work significantly expands the amount of surface area on Mars known to have once been water-laden, and it extends the period of time that the water was present.

Edited By BWhite on 1109019086

flashgordon · 2005-02-26 21:54:07

The problem current martian life would have for the Gaia hypothesis is that if life took over the ecology of mars, why hasn't it kept the temperature good for life there? The answer as I do believe already pointed out is that the planet was to small to keep the gases in regardless of how hard life fought for itself on mars.

As for multi-cellular life on mars, I don't know. People say we don't know why multi-cellular life started on earth, and maybe in a rigorous sense, we can't say why, but I've read pretty good ideas on why multi-cellular life started here on earth.

When resources decline, life combines. Biologists have some interesting living examples of this where a colony of individual cells self-organizes into a single multi-cellular slug when the surrounding resources get to small. I do believe they call it a slime mold.

And so the question becomes why did multi-cellular life arise six hundred million years ago? The answer could quite possibly be that the earth went through a snowball earth phase, where the earth was almost completelly frozen over(the equator regions may have been a sludgeball earth according to recent analyses of the snowball earth idea).

This idea makes me think of what would have happened on mars when it went cold. Could it have already gone through a snowball mars period and created multi-cellular life? Or, could mars have gone cold gradually enough(because Gaia-mars would have done everything it could have to keep conditions right for life), that multicellular life could have formed(mostly in the sea just like here on earth)? Supposing the latter, i would think finding these multi-cellular mars beings would be stranger than the burgess shale and just as challenging; you'd have to have a permanently manned mars base of scientists who would have to look for the tiniest multi-cellular beings(burgess shale multi-cellular beings were mostly quite small; only one farelly big one).

In the end, there never was intelligent life on Mars, and any multi-cellular life is going to be hard to get to without a type two civilization.

Shaun Barrett · 2005-02-27 00:50:30

Interesting thoughts, Flashgordon. :up:
I agree with you that there must be a limit to the ability of a living system to regulate its environment. Even an ecosystem as diverse and well-established as Earth's would surely have trouble maintaining itself if most of the atmosphere disappeared and average global temperatures dropped to -55 deg.C!

Looking to the future, apparently Earth's tenure as an abode for life has 'only' about a billion years left to run. All of life's checks and balances will be powerless by then to combat the inexorable increase in solar energy output. Our home planet will overheat and terrestrial life will be destroyed - despite Gaia.

As you say, finding fossil evidence of macroscopic multi-cellular life on Mars may well require a permanent presence by scientists able to conduct unlimited field excursions.
But serendipity could yet come to the rescue and Spirit or Opportunity could stumble across a perfectly preserved fossil at any moment. Stranger things have happened.
If Mars Direct had been adopted vigorously by NASA as soon as it was devised by Dr. Zubrin, we would have had a couple of teams of scientists and their results back from Mars by now and a virtually continuous human presence there. It's certainly not impossible that, if there are any macroscopic Martian fossils to be found, we might conceivably have had samples of them in terrestrial laboratories today.

I'm a bit of a Dr. Chris McKay fan and I believe he is open to the possibility that life could have developed earlier on Mars than it did on Earth. If so, multi-cellular life might have appeared quickly enough to catch the end of the hypothetical warm/wet conditions many scientists seem to think predominated there in the first 1 - 2 billion years.
And as you suggest, the worsening climatic conditions may even have served to accelerate cellular cooperation, as is thought by some authorities to have happened here 590 million years ago, in the wake of a 'Snowball Earth' episode (?).
Fascinating stuff! :up:

[Keep watching those images from Spirit and Opportunity!! You never know ... :;): ]

flashgordon · 2005-02-28 02:06:17

I think it was the "Rare Earth" guys who have suggested that the earth's life does not have the full four billion years left that the Sun has before it really does go "Red Giant" phase; i forget, but I actually think they suggested there is only really five hundred million years left before Gaia starts struggling . . . well, if we are not off and out of here by then, then we've probably destroyed ourselves anyways!

Shaun Barrett · 2005-02-28 04:46:04

Flashgordon:-

I forget, but I actually think they suggested there is only really five hundred million years left before Gaia starts struggling . . .

Yes, I remember reading something to that effect. As far as I can tell, life will begin struggling at about 500 million years from now and, aside perhaps from a few forlorn colonies of subterranean thermophilic bacteria, will be extinct here in, at most, 1 billion years.

This, to me, is a profound tragedy. Life, in one form or another, has existed here for maybe 4 billion years and Earth is its only known refuge. To think that we're in the last 20% of our home planet's 'life' span is somehow unconscionable and puts me in mind of the poignant words of Dylan Thomas:-

"Do not go gentle into that good night,

Old age should burn and rave at close of day;

Rage, rage against the dying of the light."

I just hope that whatever intelligent species exists on Earth in half a billion years will find some way to preserve Earth's legacy of life - so far the only life we know of for sure in a vast and lonely universe. ???

extrasense · 2005-03-07 11:33:07

This, to me, is a profound tragedy.

"We are but older children, dear,
Who fret to find our bedtime near."

You must worry about the brain dead NASA first.

:band:

flashgordon · 2005-03-13 15:26:38

I was just re-reading some more of Asimov's "Extraterrestrial Civilizations"(I was re-reading it years ago, but decided the last couple of chapters probably weren't much worth to read; was I wrong or what!?), and he had mentioned an idea of why the Cambrian explosion, or the onset of multicelluar life took so long; because the ozone layer hadn't developed enough till then; anybody know of any confirmation of this idea?

srmeaney · 2005-03-20 17:16:13

With regards to different rues for Bacteria and Elephants, not really. If you as bacteria live in a foot print, and a Scientist declares, these bacteria live in a hole they dug themselves, The next Scientist who tells you that elephants walk rather than fly is going to be stoned out of town by his peers.

Shaun Barrett · 2005-03-20 17:32:20

Flashgordon:-

I was just re-reading some more of Asimov's "Extraterrestrial Civilizations"(I was re-reading it years ago, but decided the last couple of chapters probably weren't much worth to read; was I wrong or what!?), and he had mentioned an idea of why the Cambrian explosion, or the onset of multicelluar life took so long; because the ozone layer hadn't developed enough till then; anybody know of any confirmation of this idea?

No, Flash.
But I believe scientists have concluded, from the study of what are known as 'banded iron formations', that Earth's atmosphere became oxygen-rich about 2.25 - 2 billion years ago. And I assume an ozone layer would have formed at the same time (?).
Yet the 'Cambrian explosion' of multicellular life forms didn't occur until about 590 million years ago. We had the oxygen, and presumably the ozone protection against U.V., some 1.5 billion years before this apparently sudden event - so why the delay? ???
I think it's still a mystery.

SpaceNut · 2006-05-29 19:14:03

Where there is water you need toFollow The Nitrogen To find Extraterrestrial Life

Nitrogen is essential to the chemistry of living organisms.
"It's hard to imagine life without water, but it's easy to imagine water without life," Nealson said.
The discovery of nitrogen on the Red Planet would be a different story.
"If you found nitrogen in abundance on Mars, you would get extremely excited because it shouldn't be there," Nealson said.
The reason has to do with the difference between nitrogen and carbon, the other indispensable organic element.
Unlike carbon, nitrogen is not a major component of rocks and minerals. This means that any substantial organic nitrogen deposits found in the soil of Mars, or of another planet, likely would have resulted from biological activity.

RedStreak · 2006-06-01 21:56:31

Possibly the Cambrian explosion is connected to the global freezings that hypothetically occured on Earth; they have found more and more evidence that these events actually happens, and I would imagine on a wetter Mars such events occuring over longer durations. I've read "Rare Earth" so its interesting to compare Mars to such circumstances.

The trouble is for all we know of Mars we're still left with alot of blanks. Most of what we've learned on Earth's history is due to the fact we can physically examine the rock layers; there's a chance with the layers Opportunity found some of Martian history could be deciphered in the near future but we need more physical evidence.

The only thing I am certain about Mars is that, alive or dead, it has a geologic history that will no doubt differ radically from Earth. No doubt it possessed water, certainly running river systems and seas for at least a few million years, and had its ice ages.

Stability of its climate is the chief factor one way or another: can Mars retain its water vapor, does the lack of a Moon and a wobbling axis shift its climate quickly?

I imagine this and the atmosphere's current condition suggests Martian life, if it appeared, developed alot differently than Earth's. Maybe they never developed an oxygen-based metabolism. Perhaps another mechanism was, or is, at work.

dicktice · 2006-10-15 15:17:02

Just a thought: If Mars possessed surface water way back then ... we should be able to recreate the surface conditions by encapsulating crarters and reconditioning the atmosphere within domes. Terraforming the craters only, shouldn't then be so hard, eh?

RedStreak · 2006-10-15 16:18:50

I suggested encapsuling the Hellas Crater in a Terraforming forum myself so your idea goes with mine just well.

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