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ToSeek
2004-Dec-03, 06:03 PM
Water is not an essential ingredient for Life, scientists now claim (http://www.spaceref.com/news/viewpr.html?pid=15568)


Billions of dollars are pumped into extraterrestrial exploration each year in the search for the ultimate prize - the discovery of life on other planets. But are we looking in all the right places? Prof Steven A Benner, who is working with NASA on the design of the next generation of Mars probes, believes that life could flourish without any need for water. In the December issue of Current Opinion in Chemical Biology, he and his colleagues at the University of Florida describe how organisms could survive in exotic environments such as on Saturn's moon Titan.

Evan
2004-Dec-03, 06:13 PM
Seems like a lot of hand waving going on there, been watching Dune too many times...

Scientist said

Benner suggests that 'RNA organisms' might still exist.

I thought that those are called viruses.


"He even wonders if we may have missed exotic forms of life here on Earth. "This question is not as absurd as it might seem," says Benner. "Just 50 years ago...life in the deep ocean was not known."

Yeah, and neither were many other things.

Ilya
2004-Dec-03, 06:30 PM
Some scientists have speculated about life not only without water, but without chemistry -- such as self-organizing magnetic structures inside stars.



"He even wonders if we may have missed exotic forms of life here on Earth. "This question is not as absurd as it might seem," says Benner. "Just 50 years ago...life in the deep ocean was not known."

Trouble is, how would we recognize it as "life"? If aforementioned magnetic creatures exist inside the Sun right now -- or even in a more accessible place such as Sun's corona, -- we'd have no idea how to look for them, or even recognize one if we were staring right at one. Unless it did something completely "unnatural", and for a long time, such beast would look to us as just another magnetic eddy. Even if it did behave manifestly different from other magnetic eddies, "it's alive!" is not a theory your typical astrophysicist* would come up with.

*Gregory Benford is an astrophysicist and [my personal absolute favorite] hard SF writer. In early 80's he looked at the radio images from the Galaxy's center, which display arcs of positron-rich plasma about 100 light-years across rising out of the plane of accretion disk surrounding the central black hole. His immediate thought was: "This looks artificial." Benford based much of his Galactic Center novels on this observation. To this day, there is no satisfactory explanation to these plasma arcs. Maybe he is right! :)

Russ
2004-Dec-03, 06:47 PM
It is my opinion that we now know 1000 times what we knew about life in 1904. That means the we now know 0.00000000001% of what there is to know about life. 8)

That means there are huge numbers of possibilities about life and types of life, we have yet to discover. Let's face it, it was the mid 1970's before we knew about the colonies of life around the thermal vents at the bottom of the ocean. There are probably 1000's of similar discoveries yet to be made. :)

I read in the paper this morning that the Spirit and Opportunity crowd had found absolute proof of flowing water on Mars. That probably means that the scenario above is duplicated on Mars to some extent.

I find the prospect that we have so much to learn very exciting. :) :D

frogesque
2004-Dec-03, 08:30 PM
Russ wrote:


....
I read in the paper this morning that the Spirit and Opportunity crowd had found absolute proof of flowing water on Mars. That probably means that the scenario above is duplicated on Mars to some extent.
....


I wouldn't believe all you read in the papers if I were you.

Russ
2004-Dec-03, 11:10 PM
Russ wrote:


....
I read in the paper this morning that the Spirit and Opportunity crowd had found absolute proof of flowing water on Mars. That probably means that the scenario above is duplicated on Mars to some extent.
....


I wouldn't believe all you read in the papers if I were you.

Well it's reported here (http://www.space.com/scienceastronomy/opportunity_water_041202.html.) at Space.com and a few other places I looked, so there must be at least some verasity to it. Heck, there will probably be somebody refuting it in another week or so. :roll:

Evan
2004-Dec-03, 11:39 PM
The idea that there was flowing surface water on Mars is completely unremarkable to me. I'm not sure what all the fuss is about. It's pretty hard to explain some of the pics otherwise. There aren't too many other candidates for the sort of erosion seen in these pics.

http://vts.bc.ca/pics/mars1.jpg

http://vts.bc.ca/pics/mars2.jpg

fossilnut
2004-Dec-03, 11:41 PM
"Billions of dollars are pumped into extraterrestrial exploration each year"

Where? not that I know of. I wish it was billions each year.

Zjm7891
2004-Dec-04, 12:20 AM
The article probably classified all of NASA as "extraterrestrial exploration" since their budget is in excess of 17 Billion dollars

eburacum45
2004-Dec-04, 08:02 AM
Ammonia based life has been suggested many times, particularly by the great JBS Haldane, as ammonia could support many organic reactions taking the place of water, and this biology might be viable over a range of temperatures similar to but somewhat lower than our own.
The trouble is water might become a poison in such circumstances just as ammonia is to water based organisms. Water is very, very much more common than ammonia, so a biology based purely on ammonia is unlikely.

But not all Earth based organisms are intolerant of ammonia; some nitrifying bacteria use ammonia as a source of chemical energy; putting the shoe on the other foot, perhaps a water tolerant ammonia biology could use water as a source of chemotrophic energy.

archman
2004-Dec-05, 12:49 AM
The deep-sea chemoautotrophic bactera I sometimes encounter in my samples either use sulfides or methane for juice. Methane's the least efficient.

My aquatic microbiology text quotes a maximum of 40% water loss to the hardiest known microbes before growth stops.

Intracellular water's still considered the most limiting condition for bacterial life. Even the extreme halophiles need it.

Last I heard (late '90's), nobody had found a microbe capable of living within solid ice or steam either.

Swift
2004-Dec-06, 02:43 PM
I agree with Evan that it sounds like a lot of hand-waving. It seems plausible that the only fundamental requirements for a "chemistry" based life-form are the right temperature range and an energy source, but they don't give any alternatives. eburacum45 did a better job, with the mention of ammonia as one of the possibilites we've discussed here before.

By the way, I say "chemistry" based, to differentiate with ones based on things like energy beings and other Sci-Fi ideas.

I would not say either RNA based life or chemoautotrophic life are examples of non-water life, since both of them use water as the fundamental solvent, even if they use different chemistry for energy generation or genetic encoding.

By the way, IIRC, while virus are the only current RNA life, there has been speculation that early life on Earth (stuff closer to bacteria) may have used RNA. The current system is to store the genetic information in DNA, transfer it to RNA, and then synthesize proteins from the RNA. By storing the genetic information directly in RNA, you can simplify the system. There is also evidence that RNA may directly catalyze some reactions, thus eliminating the need for some protein synthesis.

SkepticJ
2004-Dec-06, 04:10 PM
It is my opinion that we now know 1000 times what we knew about life in 1904. That means the we now know 0.00000000001% of what there is to know about life. 8)

That means there are huge numbers of possibilities about life and types of life, we have yet to discover. Let's face it, it was the mid 1970's before we knew about the colonies of life around the thermal vents at the bottom of the ocean. There are probably 1000's of similar discoveries yet to be made. :)

I read in the paper this morning that the Spirit and Opportunity crowd had found absolute proof of flowing water on Mars. That probably means that the scenario above is duplicated on Mars to some extent.

I find the prospect that we have so much to learn very exciting. :) :D

Being that there is as many stars in the universe as there are grains of sand on all the beaches of Earth we have a lot of places and things to learn about. Even when we have a theory of everything that doesn't cover the trillions of species that are probably out there. We're going to have fun for millions of years.

Ilya
2004-Dec-06, 04:17 PM
Water is very, very much more common than ammonia, so a biology based purely on ammonia is unlikely.

In other words, wherever you find abundant ammonia, such as moons of gas giant, you also find much more abundant water. And while ammonia stays liquid at lower temperatures than pure water, water-ammonia mixture stays liquid at much wider range of temperatures -- both lower and higher. IIRC, ammonia solution with the lowest freezing point 30% NH3, 70% H2O. So ammonia can never be the ONLY solvent because any naturally existing liquid NH3 will be diluted with rather larger amount of water.

frogesque
2004-Dec-06, 04:32 PM
Russ wrote:


....
I read in the paper this morning that the Spirit and Opportunity crowd had found absolute proof of flowing water on Mars. That probably means that the scenario above is duplicated on Mars to some extent.
....


I wouldn't believe all you read in the papers if I were you.

Well it's reported here (http://www.space.com/scienceastronomy/opportunity_water_041202.html.) at Space.com and a few other places I looked, so there must be at least some verasity to it. Heck, there will probably be somebody refuting it in another week or so. :roll:

I read your post to mean that water is flowing freely on the surface of Mars now. Whilst the evidence pointing to a wet Mars at some time in the past is now pretty conclusive, the case for current water flow is far from settled. The window for fluid water to remain stable is extremely narrow at a surface pressure of 7-10mb. Saline solutions might well extend that window but the lack of any substantial precipitation and the rate of evaporation in Martian atmosphere makes it very doubtfull. Subregolith water tables may exist and a local instability in land could result in a surface eruption but it would be short lived because there is nothing to replace the fossilised aquafed.

Photos certainly show dendritic stream like channels but for them to contain liquid water we would also see a very definite water signature in the atmosphere. So far, that signature has not been seen much above a nominal background figure of 0.03%.

Bones don't come much drier.