Thursday, August 7, 2014

Water, water everywhere, and then some drops to drink: Comet 67P/Churyumov-Gerasimenko, and the Life-Dust rationale

This week comes the news that a European spacecraft probe called Rosetta has gotten into an interesting triangular orbit around a comet named 67P/Churyumov-Gerasimenko, that itself is in orbit around our sun.  This is quite a technical and engineering feat that's interesting in its own right, because getting there required about 10 years, over 6 billions of miles of travel, orbiting around the sun to use solar and planetary gravity to give it a sling so it didn't have to use its on-board power.  And there are still technical challenges yet to come.

From the European Space Agency Rosetta project

Rosetta will orbit 67P and take all sorts of pictures and measurements, and then, remarkably, will send down a landing craft to probe even deeper.  It will find out how much ice is on the comet and what other material it may contain, presumably including carbon.  That's been a primary part of the news releases.  But why carbon, and what's so important about carbon as opposed to some other sorts of compounds? Herein lies the hype and at least an apparent major rationale for doing this since, after all, we know from various sources what comets are basically made of.  As put today by the BBC's report, "The mission aims to add to knowledge of comets and their role in ferrying the building blocks of life around the early Solar System."

This sounds interesting and like a nice justification for a many-billion Euro adventure.  Astrophysicists will learn at least some new things about the structure and composition of this particular rock.  But will 67P tell us much about anything other than itself, that we don't know already directly and indirectly about the trillions of other comets in the cosmos?  I say this because the idea that we'll be discovering the origin of Earth-life's materials seems a rationale as flimsy as, say, a clump of damp dust.  

I know very little cosmology, but one thing I think I do know, if current science is at all correct, is that the "building blocks of life" did indeed come from comets and other space-dusty rocks and detritus.   What we have long known is that water, carbon, and all the other complex molecules of life (and, for that matter, of rocks, seas, weather and the Earth entire) came from 'outer space'.  Where else could they have come from?  

These molecules are formed in processes called nucleosynthesis, that occur inside stars.  The cosmos had none of it at the time of the Big Bang.  Only when stars form, exist for a while, then explode in death, does this material get scattered into space.  Then, due to gravity and possibly other factors such as molecular adherence these molecules, essentially space dust, coalesce into larger and larger clumps, rocks that become captured in orbit around new-forming or existing stars.  All that you're made of was in turn made in some former, no-longer-existing star, long before our Sun came into existence.

The Earth, and everything on it that life is made of, got here by collapsing and accretion from space-blown material.  The stuff of 67P is just like what we already think we know was the source of similar molecules on earth.  Whether they got here during the original accretion, or by space-fall thereafter, it's the same kind of process.  We know the Earth is hit from time to time by such space missiles. The bottom line is that everything that's here got here from space.  The only somewhat relevant, but in that sense not so very important question is how much carbon and water came after the Earth existed as a big rock, and how much was part of Earth's formation.

We know with reasonable certainty that life didn't arise until there was enough water and carbon etc. here for biomolecules to form. We know roughly when that was (3-4 billion years ago, in a 4.5 billion-year old Earth).  If these vital molecules were here at Earth's beginning, than life arose only when things had cooled down enough, and perhaps water had eroded enough minerals and carbon and so on from solid rock, etc.  If the cosmic rain was responsible for some or even most of the water here (which seems very unlikely, given how prominent water is all over the universe), that tells us little that's different.

Pro-science or a science spoil-sport?
So is such a mission worth its cost when there are things to do with public funds other than to develop sky toys for scientists to play with?   We are in favor of science--good science, properly represented.  But science should tell less puffed-up stories, and the public should be better-informed.  

In this case, better-informed would be to be told that (unless cosmological theory is missing something important today, which is not what the press releases suggest) all Rosetta is doing is poking around in one sample of the stuff we were made by, that all came from space, as did the Earth itself.  If even knowing that, we still want to spend the funds on what are really little more than costly real-life video games, great!  

For those of us without a major disease and who have shelter, security, and enough to eat, this is interesting stuff to watch, not more costly than cable TV subscriptions (maybe less, depending on your channel line-up).  But to hype this as is being done, gives the impression that Earth got here by some other means than gravitational accretion of former star detritus.  That's misleading, bad science. Why is such need felt by the scientists (or the institution's PR office) to give it such spin?  Is it that they realize that without the spin they'd have no funding?  If so, then the public is being bilked.  If not, then let's have real science from these experts.

Here's something much more interesting
To be fair, some of what we get from our space cadets really is interesting for more than a "Wow, how did you manage that?" factor.  Yesterday also, NASA (perhaps not wanting to be upstaged by the Europeans?) released this image of a near-perfect hexagonal pattern, referred to as a 'storm', on Saturn's north pole region:

Photographed from the top of Saturn.  From NASA
The NYTimes has a wonderful video narrated by Dennis Overbye showing this formation along with other features of Saturn.  It's a curious formation, a fluid aspect of the north pole's weather. 

As a former meteorologist myself, I find this very interesting.  Spacecraft first found this many years ago, but we only get an occasional direct look.  The curious aspect of the pattern, is that it's a hexagon rather than more sinuous wave such as we get here in Earth's weather (and seas, for that matter).  How can fluid dynamics generate such a rigid-appearing, angular form on a basically spherical surface? Is something on Saturn alien to our own planet?  Different physics?

In fact, the report says that physicists have now generated similar patterns in the lab, identifying the conditions that are responsible and showing that nothing strangely unearthly is going on in our sister planet.  Still, seeing these far-off things close-up for the first time has lead to learning, and is captivating--even if, as in 67P, it doesn't show us anything alien to our experience here at home.

These images from far away evoke an emotional awe: there truly is, way out there and so far beyond, more of what we see right here.  It exists, all alone and cold and dark, perhaps known to other creatures, yet the same as what we have here.  Little ice crystals, rock dust, shapes we recognize that we might find in our own back yard.

These thoughts reinforce the amazing, remarkable fact that there really do seem to be laws of Nature, that what we can see nearby applies way out there where we can hardly catch glimpses--a point Isaac Newton stressed. Very much to think about.  Good science really does tell us about the nature of the world, in ways no other means has yet been able to do.  We puny humans, blobs of stuff that evolved from space-stuff, have figured this out!  That's a thought of cosmic proportions.  


David Evans said...

I agree with you about the carbon hype, but surely one way science progresses is by actually checking what we think we know. And possibly finding out something that we didn't know. I would like to see similar missions to each of the main types of asteroids. We will, sooner or later, have to try and move such objects away from a collision course, and the more we know about them the better.

Ken Weiss said...

Reply to David Evans
Exploring space to see what might be there that we don't expect, or even (harder for me to see) because we may need to intercept things, is a justification that is not origin-of life-baloney.

But unexpected discoveries is in a way a justification of last resort (one routinely invoked for business as usual in genetics). Surprises can come from any sort of study, not just by repeating more of the same expensive study again and again. So I think we should invest in studies with prospects of really new findings.

If there were cogent reasons to think that current cosmology is fundamentally wrong--or to investigates its unknown or weaker aspects, that would be one thing. But what kind of new finding can result from poking a hole in the occasional comet? We do have meteors on earth, etc. as cheaper test cases.

Space exploration is certainly interesting and exciting (I'm old enough to remember Sputnik and the moon landings). If the hype were gone, then it becomes a matter of societal priorities, and here I feel that until we take care of business better at home, where we face many needs that could be addressed by properly done science, we should not be spending billions on what is mainly technology-building, or fun, or astro-job protection. Or--seriously!--why not let the video game and movie industries pay for it?

But when at public expense, it should be justified it on actual scientific grounds.

Anonymous said...

"So is such a mission worth its cost when there are things to do with public funds other than to develop sky toys for scientists to play with?"

Anyone connecting the dots between your various posts and extending them to their logical end would argue that the centralized system of funding (research, war, welfare) will blow up rather than correcting itself. I am puzzled that you do not come to the same conclusion and go to the follow up question - what next.


Ken Weiss said...

Reply to Manoj
Well, blow up? Maybe implode would be as likely. In any case, I don't know if the dots can be connected. We can't expect any aspect of complex society, including scientists, to act selflessly, nor can we trust any element to tell everyone else what's best to do with common resources.

History has not shown any really 'fair' version of complex society. What we can perhaps hope is a move towards more equity. When it comes to science, we can trim back the university welfare system, and really set priorities in a way not tied to empire-building.

But there will be disagreement both for selfish reasons and because people see priorities differently.

Catastrophes build from time to time, like world wars and plagues, and hopefully we can avoid that sort of thing and stabilize in some way. But who knows how to do it fairly and wisely?

David Evans said...

I don't think meteorites on Earth are a representative sample of comets. Assuming they did come from comets, any water or hydrocarbon ices or complex organic compounds would either be stripped off during re-entry or would evaporate or be eaten by bugs after landing. The only way to find out in detail what a comet is made of is to go there.

And the answer is very relevant to at least 2 questions of great interest - how did life start on Earth and how likely is it that life exists elsewhere. Hype apart, those are some of the things the public most wants to find out.

Ken Weiss said...

Well, good point about meteors, but I think we just disagree about the two main questions related to life. I have been awed by space projects, but I see growing cost and waste relative to serious science-dependent problems here at home, and hype everywhere that misrepresents the science, which I think the life-aspects of this story do. In that sense, as I said in the post itself, I think it actually is bad science, not public education.

And if it's just for public entertainment value about life on Planet X, then I literally think the entertainment industry should pay for it. If it's covertly about military technology why not at least admit it?

This one cost 1.2B Euros, I read, and surely the video game and other such industries could cover those costs, and save public funds for serious issues (and you may know that we criticize huge waste in biomedical sciences, too, and for the same sorts of reasons).

Anyway, a constructive disagreement is something worth thinking about and trying to understand.