Wednesday, September 12, 2012

Life in the cold zone? And in space?? Part II

On Monday we described the existence of subglacial lakes in Antarctica (and elsewhere in the solar system), and the effort to bore into them to sample their water and surfaces.  Geochemists and geologists have various questions they'd like to answer about this interesting phenomenon.  Such ice sheets initially form on the surface just as it does in the winter where you and we live, but in an ever-winter climate it never thaws.  As it becomes ever thicker, the insulation it provides from solar heating, the pressure at its base, and geothermal heating from below melt water at the earth-glacier interface--it liquifies the ice there.  The water then builds up over time in to a sizable lake, and will naturally also follow available ground channels to connect with other such lakes and so on.  Maybe even to connect to subsurface water.

On Earth, there is an old saw that where there's water, there's life, so one question is whether that is a rigorous enough theory to suggest that there's life in these subglacial Antarctic lakes.  And since there is similar subglacial liquid water elsewhere even in our own solar system, such as on Jupiter's moon Europa, the question is naturally raised as to whether there's life there, too.  Or all over the universe.

Do Earthly matters matter?
What would we expect to find in water samples brought up from probes into Antarctic subglacial lakes?  Well, we know that millions of years ago, there were complete living ecosystems, even tropical in their abundant and diverse life.  So, if they could last long enough, remnants must have once been on the surface when it initially froze over and could still be there today.  That would range from what would now be fossils, to perhaps the kind of frozen, mineralized microbial life that has been found at the surface of Antarctica.  So it would be no total surprise to find that kind of evidence (though this project is not going to bore into the ground surface below the lake, where fossils of multicellular organisms might be most likely to be found).  We have to leave such speculations to geologists and paleontologists.

One could also not be surprised if there are organic molecules in the water that were once part of that ancient life, and were embedded in the initial ice layer as it formed.  Conditions may have been stable enough that such molecules didn't degrade.  DNA is unlikely to have been preserved intact, but many kinds of molecules and perhaps even nucleotides (DNA building blocks) might have survived the Long Chill.  Finding them would be at most mildly interesting (since we know they must have been there at one time).  Organic molecules continually rain down on Earth from space, so they would have landed on the forming ice, and hence be in the melted subglacial water.

Since we know that fish and many other types of life have adapted genetically to be able to live in the frigid waters around the poles, could we find them in these subglacial lakes?  It seems unlikely, to us at least, for several reasons.  First, terrestrial life would have had to survive the long eons of climate cooling and then unmelting snow, eventually covering the entire surface leaving nothing to eat, and then somehow adapted to live embedded in ice for millions of years until the Big Thaw at the bottom.  So this seems highly unlikely and we doubt the lakes' explorers expect that kind of life.

Darwinian adaptation can be remarkable, but it seems to be a stretch in this case, unless signs of life that were found were from things that seeped up from underground or from the surrounding oceans. 

Perhaps micro-organisms could have adapted to the cold, but where would they have lived during the millions of years that the earth-glacier interface was frozen solid?  It would probably have had to be under the surface, surviving and adapting somehow until a liquid lake formed--perhaps they lived in underground liquid water and then seeped into the subglacial lake as it formed?

Most likely one would find simply signs of life--molecules of life, but that would in itself tell us nothing since it would be expected for the above reasons (that there was life there before the freeze).  In a way, perhaps we would be surprised not to find such molecules, though in this case the planned samples will be small--only a few hundred ml of liquid--so a very chancy sampling of the lake.

So, one wonders just what the evidence for life would be that would be any sort of surprise.  Even if it's true that on earth where there's water there's life, it doesn't mean that the 'life' is alive.  It would take some clever argument to suggest how adaptations would have been possible unless as we suggested above it were from subterranean water and/or perhaps had some deep channels to the water surrounding Antarctica.

In any case, it will be interesting to see what is found.  It may tell us things about geological history and processes.  And maybe we, not geologists, are missing some points of the goals of the expedition that didn't come through in an interview program on the BBC or on the Wiki pages devoted to subglacial lakes.

Life in space
But what about the sexy hint that it will tell us about life on ice-bound orbs like Europa?  Just because, or if, it's true that where there's water there's life on earth, has no bearing whatever on the relevance of this kind of generalization elsewhere.  Water is compatible with life, at least life as we know it here, and life evolved from watery beginnings and hence depends on water, but water doesn't cause life.  What's in the liquid water under Europa's icy coat may be interesting for all sorts of reasons, but to justify it on the grounds of it being evidence for life, and using Earth as a precedent, is the kind of stretch that can be very misleading.

The public is hungry for science stories (and for science fiction), and NASA does big business in 'astrobiology', at least partly if not mainly as a marketing component.  And if half our population doesn't believe that evolution took place, how can we expect them to be able to discriminate the fairy tales used to justify the cost of space exploration?  Maybe it would be better to be a bit more critical in what is said to scientists and public alike, about the value and interest in simply learning more about the universe--genuine excitement about the genuinely interesting knowledge of existence that can be gained.  Or, equally, whether that value is worth the cost given other problems that people face here on the surface, where it's warm and indisputably lively.

5 comments:

Steve Bates said...

"Or, equally, whether that value is worth the cost given other problems that people face here on the surface, where it's warm and indisputably lively." - KW

The budget for the US Department of Military Adventurism, um, excuse me, Department of Defense, exceeds that of all other nations in the world... combined. Are you really saying that a significant competitor for dollars for social programs is... exobiology research? Really?

Anne Buchanan said...

(This is Ken replying, not Anne):
Your question is a kind of non sequitur. I personally am saying that we are throwing money away on Mars research falsely rationalized given needs here on earth. Or even the much lower cost of boring into subglacial lakes.

I don't mean to be a spoil-sport about things that are pretty interesting, as exploration is. But that is wholly unrelated to whether the Defense Department needs what it gets or does what it should.

Much as I see the point you make about DoD, one can argue on the basis of millennia of history that except for some generally small-scale or short-term exceptions, countries who don't have a substantial military are victimized by other countries that do--whether that's a nice thing or not.

Given the number of nasty, greedy people and the route to power that nationalism and jingoism provide, one can't just dismiss defense as in itself wrong. However, that doesn't mean that whatever the DoD does is called for, or in the best interest of the country, nor that to defend us realistically actually requires everything they get in terms of resources. The size of their budget is a legitimate socially relevant decision.

So, yes, in terms of relative squandering of resources NASA may not be particularly culpable. But they, and NIH and others are feathering nests that don't need to be feathered, in my opinion.

Steve Bates said...

Is defense money spent on defense (something which, I agree, is necessary)? IMHO a great deal of it is spent on what you would call the feathering of nests. But that's off topic, and I'll defer discussion of that.

My point is that the taxpayer, rightly, sees his/her tax dollars going toward one big round pie, divided among the whole range of government budget items. So social programs indeed do compete, in a sense, with Mars missions, astrobiology, SETI, etc. But they also compete, arguably just as directly, with an obscenely bloated "defense" budget that could be cut just by not engaging in so many discretionary wars. War is the American nation's hobby in the 21st century, and that is not a good thing.

Cutting back on development of crowd control weapons (LRAD etc.) used so far primarily to abridge demonstrators' First Amendment rights would also reduce costs a bit; such weapons have nothing to do with actual defense of the nation, and strike me as a real temptation to regular use for oppressive purposes.

I am content with redirecting science funding to other scientific endeavors on Earth if that is appropriate. But I don't see that as the tradeoff actually being made by the American government, no matter which party is in power at a given moment. Excessive military spending has a way of creating self-fulfilling needs for new and exotic weapons, many of which have little to do with defense... presidents ask themselves, "if we have it, why not use it?" Drones are a good example.

And I think there is a real danger that funding of legitimate science will be shortchanged in the name of cost-saving measures when science is not a major fraction of costs in the first place, compared to that overstuffed "defense" budget.

Ken Weiss said...

My only point, and it's not a disagreement with the issues you raise, is that I think that a lot of hype is continually pouring forth to defend or justify science spending that should not be a priority, given other needs that affect real people's lives and that could productively be addressed instead of some of what we are doing.

How much money should be collected and spent on science is a related but somewhat separate question. Likewise, how much should be spent on defense, and what that should be used for.

I just think that as interesting and thought-provoking as it is, Mars missions should be very low priority (and manned ones no-priority) relative to major human-life-here issues. In health resesarch, as you know, I think we are throwing huge amounts (if maybe not relative to the cost of a nuclear submarine) on 'omics' rather than focused on questions that could actually be answered to the benefit of individual lives.

Babu Cbe said...

"Water is compatible with life, at least life as we know it here, and life evolved from watery beginnings and hence depends on water, but water doesn't cause life"

Interesting point about water and life! A useful conflation that has been taken for granted and for so long.

So much sixties like hopeful interpolation! And lots of damning with logic.

We sure know the ingredients of life, but are yet to be able to recreate one. The situation being akin to having all the ingredients of a meal with us, but nothing can be done for the (master???)baker has gone missing.

Assuming that these ingredients are sufficient and/or necessary and particularly in the baker's absence reminds one of school boy logic, more presumption than called for, and more pretension than publicly acceptable.

Life seems to call for new explanations, perhaps a new physics. And I suspect that sometime in the near future, the physics of life may be more interesting as its biology, or at least as interesting as.