Discussion and news about the modern effort to understand the nature of life on Earth, finding planets around other stars, and the search for life elsewhere in the universe

Sunday, March 6, 2011

There's Something About Meteorites

Yikes. This is a post I wasn't going to write. Claims of microbial fossils in carbonaceous chondrite meteorites in a slightly dodgy feeling journal with a peculiar angle on publicity and the all-to-laughable 'news' reporting of certain media networks really is a sticky package. I can feel my blood pressure rising.

However, a couple of conversations had me thinking about this a little more, and after reading some rather sharp and apparently hurried public criticisms of said work (can people really not be bothered to spell someone's name correctly?) I felt there was perhaps something to discuss and add after all.

The paper ruffling some indignant feathers is "Fossils of Cyanobacteria in CI1 Carbonaceous Meteorites: Implications to Life on Comets, Europa, and Enceladus", by Richard B. Hoover. The bottom line is that Hoover (a long established and respected NASA scientist) is claiming to find evidence for fossil-like remains of microbial life inside carbon-rich, highly friable meteorites, based largely on electron microscopy investigations. He then goes on to speculate that the original organisms were a) extraterrestrial in origin, b) perhaps originally inside comets, and c) these could all be related to species that would find a home in the ice on Europa or Enceladus - right down to exhibiting pigmentation consistent with those locales. Wow. That's a lot to take in.

I'm going to first ignore the rather non-mainstream nature of the 'Journal of Cosmology' that this paper appears in, as well as their odd call for open-source commentary. That's really a whole other discussion that I'll pick up later on. However, as I'll explain below, this work didn't just pop out of a vacuum. The paper itself is chock-a-block in some respects, less so in others. As some of the critiques have pointed out, there are big and serious questions about terrestrial contamination of the meteorite samples (most have been in storage for decades). Also there are the funky compositions Hoover finds for the variety of bizarre looking microscopic structures that are his principle evidence of 'life'. Some of these structures are indeed spooky and intriguing - filamentous threads just a few microns in length, seemingly composed of a core and a sheath. Structural similarities to known microbial forms are certainly suggestive. Elemental compositions are probed, but without extremely clear calibration (again, as pointed out by some of the critiques), and are decidedly odd.

My take on it all requires a little disclosure. About five years ago I was invited to a SPIE meeting in San Diego that Richard Hoover was chairing - a respectable enough venue. I guess I arrived as an interested observer. Over a few days we heard about a variety of research into astrochemistry, terrestrial microbiology and paleo-microbiology, and Hoover's findings in both extreme Earth environments and meteorites. As a skilled microscopist he had some great stuff to show off. Bacteria in permafrost emerging from spore states and yes, the bizarre looking forms from deep inside carbon rich meteorites. There was a lot of discussion about contamination and the like. The off-kilter elemental composition of the microscopic meteorite structures wasn't consistent with contamination, nor was the fact that some of these meteorites utterly disintegrate at the slightest contact with water - suggesting that their storage might not have been so haphazard after all. There was a lot of head scratching.

My problem was the same then as it is now. I had no counterpoint, no idea what the insides of a carbon-rich meteorite should look like at a microscopic level if never touched by living organisms. Heck, for all I knew these weird and fascinating structures were perfectly reasonable consequences of non-biological zero-g chemistry, but there was no calibration for that. And I'm not sure there is any calibration now. Fossils of microbial life on Earth are also pretty tough to find and study, so that isn't a great help in this case. Hoover clearly felt then, as he does now, that he was finding something genuinely important and interesting in the meteorites. Maybe he is. Sure there are flaws in the way the data is presented, and the claims are stretched beyond the comfort zone, but I think it's still worth understanding what's going on. The catch-22 is that until someone from the outside takes this work seriously enough to perform that counter-investigation I don't think anyone is going to pay too much attention. The new tarnish doesn't help.

I feel my ire directed towards the Journal of Cosmology. For those of us trying very hard to develop a still emergent 'inter-discipline' like astrobiology, free from past nonsense and wish-fulfillment speculation, the kind of sensationalist, half-baked, awkward promotional tactics they are employing is poison. This is not how science should get reported, it's based on a fantasy about the nature of discovery. Yes, every so often a study comes along that blows us all away. Game-changers happen. But they almost never, ever happen like this. Talk about shooting yourself in the foot.

It's too bad - meteorites are really, really fascinating.

3 comments:

mikhailway said...

Maybe you'll find it funny that I went to NYU on Friday to hear Goldreich speak on ancient impacts. He started out by saying he's much more interested in Chondrites, but that they were too hard to work on ;-)
Too bad he didn't comment on this "discovery", or maybe he did and I didn't get the joke. --mike

Caleb Scharf said...

Nice! Yep, and the fact is there are so few 'intact' carbonaceous ones that they're extra intriguing.

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