New Findings On Alan Hills Meteorite Point to Microbial Life
Written by Nancy Atkinson
Scientists caused quite a stir in 1996 when they announced a meteorite had been found in Antarctica that might contain evidence for microscopic fossils of Martian bacteria. While subsequent studies of the now famous Alan Hills Meteorite shot down theories that the Mars rock held fossilized alien life, both sides debated the issue and the meteorite is still being studied. Now, Craig Covault in Spaceflightnow.com reports that a new look at ALH84001 provides "evidence that supports the existence of life on the surface of Mars, or in subsurface water pools, early in the planet's history." Covault says we can expect a public announcement by NASA Headquarters within a few days.
Research using a more advanced High Resolution Electron Microscopy than was in existence when the initial findings were made 13 years ago has provided the new evidence. Covault reported that the "laboratory sensors are being focused directly on carbonate discs and associated tiny magnetite crystals present inside the meteorite Allen Hills ALH 84001." The data reveal information that counters a "wide range of opposing theories as to why the finding should not be supported as biological in origin."
The new findings were reported in the November issue of the respected journal Geochimica et Cosmochimica Acta, the journal of the Geochemical and Meteoritic Society. The authors include Kathie Thomas-Keprta, Simon Clement, David McKay (who led the original team), Everett Gibson and Susan Wentworth, all of the Johnson Space Center.
UPDATE: An abstract is available here.
Covault said the new work centers on what is called magnetic bacteria that on Earth, and Mars as well, leave distinctively-shaped remnants in the rock. These features test with a high chemical purity more like a biological feature than geological.
For more details, read the article on Spaceflightnow.com
Exciting! Stay tuned…
Filed under: Astrobiology, Mars
Tags: ALH 84001, Astrobiology, MarsComment policy: Be nice and brief. Don't advertise your stuff, or promote your personal theories. We'll delete any comments that break these policies. Click here for more details.
November 25th, 2009 at 9:36 am
[Sarcasm]
Magnetic bacteria? That can only mean ELECTRIC BACTERIA!!!1!11!! Because only ELECTRIC CURRENTS can produce a MAGNETIC FIELD!!!1!11!! And electromagnetism is 10^39 times stronger than gravity!!!1!!1!!
[/Sarcasm]
November 25th, 2009 at 11:20 am
How much a positive result can improve a tripulated mission to mars?
November 25th, 2009 at 11:50 am
The article in Spaceflight Now mentions that the rock sample with the alleged bacteria is 4 billion years old and was a part of the original crust of Mars. Doesn't that seem a little early for life to form? I certainly don't know much about this topic, but what a major discovery if it's true!! To think that the martian bacteria were very similar to our own is also a mind boggler!
November 25th, 2009 at 12:58 pm
Kawarthajon – Life arose early on Earth too, and and a straghtforward possibility for the similarity of Mars life and Earth life were that the life was exchanged by one of the panspermia (or transpermia) theories. This is a very exciting time.
November 25th, 2009 at 1:00 pm
Very interesting! Turn up the WOW factor to the end of the spectrum on this one!
Scenario: A Martian volcanic tube, with a volcanic mud spring bubbling up out of a deep fracture… Got critters?
November 25th, 2009 at 4:04 pm
@ IVAN3MAN
You mean that all gravity in the Universe originates from electric bacteria through a z-pinch? LOL
November 26th, 2009 at 6:58 am
Warning: don't get too excited, folks. It may look like they have found a wiggly worm on a Mars rock. There are plenty of ordinary crystallization processes that can make shapes like this. Ordinary white asbestos gives little bent fibers. The rock has been around for billions of years, and a lot can happen in that time.
Don't get me worong: there is nothing wrong with as much of the paper as I can read. The authors have been quite thorough. They have distinguished between some known processes that make shapes like this on earth. They have carbonates, and those have (probably) always been there rather than soaked in while on Earth. They seem to have done a good job.
So, what's my problem? Well, the shapes we see are either generated by (a) life on Mars or (b) something else we haven't thought of yet. Life on Mars (a) would either mean we have independent life on two adjacent planets and Drake's constant is about 1.0; or life has started on one planet and hopped to another. Either way, something very surprising would have happened. In comparison, it seems quite likely that we have missed some other process that makes these shapes. I think the authors of the paper would be happy with this statement.
Nevertheless, there are bacteria deep within the earth that live using sulphur instead of oxygen; and ones that get their energy from radioactive decay. If we get to drilling deep within Mars, we might hope to find these kinds of thing, even if the surface is sterilized by UV and chemistry. The extraordinary proof we would want for the extraordinary proposal might well be there for the finding.
"Come, Watson, come!" he cried. "The game is afoot. Not a word! Into your clothes and come!"
November 26th, 2009 at 9:39 am
@ Richard Kirk, thanks for elaborating on just how this new work relates to the original (disputed) findings published back in 2001. I was curious as to what new info on 'magnetic bacteria' now points to a biological origin. I managed to find a brief presentation of the new work by Thomas-Keprta et.al. ( http://meetingorganizer.copernicus.org/EPSC2009/EPSC2009-318.pdf ) that gives more detail about the recent paper in ScienceDirect. I agree with your 'don't get too excited' stance. Interesting but not 'proof' of biological processes.
@ IVAN3MAN, you forgot the crucial z-pinch and double layers. Tsk, tsk
November 26th, 2009 at 11:36 am
Thanks for the interesting comments TD. The article said that the rock floated around for 16 million years. Do you really think that Bacteria could have lasted that long in space and still have been viable to start life on a new planet or moon?
November 26th, 2009 at 12:27 pm
Well, this layman didn't find the paper as electrifying as he could wish for.
That said, I think the people working on this seem good. They have a fossil study approach, either from the start or because specialists have communicated concerns, so they use a massive set of predictions to test for instead of narrow characters. They seem technical competent. [Disclaimer: layman here.]
And here they again tested parts of their set of hypotheses, against competitive thermal models for the magnetite crystals found. No falsification seen, and as opposed to viewpoints in comments above in such a test unknown alternate theories don't count, so score one hat trick for the home team.
My dissatisfaction comes from two sources.
First, maybe I missed that, but I don't think they addressed the age of the finds. I don't know much about magnetite fossils, but Wikipedia claims that the oldest finds earlier are ~ 1.9 Ga. The environment was "different" (o.O), but still the extension should be discussed.
It is truly a minor point, compare with stromatolites. IIRC lately stromatolites ~ 3.5 Ga were certified as with biological origin. (By an exhaustive analysis akin to this team's work.) This is, I believe something like an 0.8 Ga extension of the methods, from ~ 2.7 Ga.
Second, and no minor point IMHO: the team has failed to test the most important character. (I think, looking at "archae-biology" papers.) Chemically deposited magnetites tend to have a log-normal distribution from simple growth processes. Biological magnetites tend to have a normal distribution with a truncation, as they grow in biological organisms that tend to have a normal size distribution when they die and moreover are inhibited in growth when they hit the magnetosome membrane.
[Arguing that alien life won't have analogous cell structures, they should at least have a membrane and if so also display a normal size distribution. And preferably have a sub-compartment of some kind, or crystal growth will eventually kill them.]
When I go back to 1997, the group have identified the need for a test in a conference paper.
And 2000 they presented a very competent paper, looking at magnetite images and skilfully transforming their 2D representation into 3D format. (I wouldn't know how to do this before. But recognizes the need after having worked with statistics on inclusions in steel factory products – which luckily happens to be rather spherical and easy to treat.)
Unfortunately they stop right before actually doing a statistical test, unless again I missed something. They are eyeballing figures in a log diagram and trying to convince the reader that the ALH84001 magnetites are akin to a biological sample from a magnetotactic bacteria, and they are, and also that they aren't log-normal distributed, which is more uncertain despite their "helpful" sketch of one such distribution.
How hard would a real, quantifiable, test have been? :-/
November 26th, 2009 at 12:54 pm
Eh? That wasn't the paper I found. They looked on magnetites, not narrow characters of unknown origin. Magnetite crystals on Earth can be from both chemical and biological origin, but the later are a discernible population and are, AFAIU, reliably known as fossils.
As I noted above, falsification tests as they did here doesn't involve unknown alternates. It is enough to against a null hypothesis at worst to see if one can reject an erroneous theory. So they achieved what they wanted.
Nitpick: It's Drake's equation. (Even if a "constant" would be a nice thing to have when the factors in the equation are more constrained.) Also, from the one sample we have life is common as it started so quickly and the easily here, and plenty of material have been found transported from one body to another in the solar system, so none of that is surprising.
More surprising would be extant life on Mars, as the bacterial communities you describe are all very complex and unique, and took a long time to develop. Compare with the ~ 1000 species that forms the communities cave researchers finds and which seems to be less than ~ 1 Ga from genetic analysis, or the many species genes that are incorporated in the rare species that can fend on their own.
Extremophiles as in archaebacteria seems to be the genetically youngest cell type out there at ~ 1 Ga, see Cavalier-Smith. And genes from them are found in the "eremites" above. [Also, these species incorporates the methanogens, the very last and apparently unlikely metabolic process developed on Earth, so Mars methane are unlikely to be biological in origin IMHO.]
All of this argues against life still surviving on Mars, as its environment turned harsh so quickly, at ~ 3 Ga IIRC. But bacterial fossils are an exciting probability.
November 26th, 2009 at 3:50 pm
@Richard Kirk
I agree even though it seems promising, it is not yet proof of real life. But it could give us a clue what to search for when we return to Mars.
Then again it is also nice to dream a bit that we finally did find life on Mars.
November 27th, 2009 at 7:14 am
"a public announcement by NASA Headquarters" ?
Exit science, welcome PR (in support of manned space programs. Grrr).
As in 1996, this will make headlines; then if and when other studies account for a non-bio explanation, it won't.
Ah, well.
November 27th, 2009 at 11:05 am
Kawarthajon – do I think bacteria or other microbial spores could survive 16 million years – I don't know but it does seem unlikely. But, whatever I think, it would need to be studied. The point you've sort of assumed is that all other microbe-carrying meteors also took 16 million years to make the Earth-Mars trip. Others could have made trip much more quickly – and for starting life – it only takes one.
It interesting to watch the scientific game of ping-pong continue for the answer to the question "Is there life on Mars". I would like to reassure all those "scientists" who don't want it found – nobody in the overall population cares anymore. The scientific jabber has bored the public senseless. And from what I can glean from decades of literature – it looks less like science in action, and more like a brilliant plan, and brilliantly executed. Congratulations. I hope the ultimate impact on humanity (of avoiding or greatly delaying the discovery of life on Mars at the cost of the public's respect of science) is worth it.
November 27th, 2009 at 11:39 am
Life on Mars has its episodes. Back in 1976 of course the Vikings found a chemical reaction which at least resembles life. Some doubts were raised though, so the results were deemed inconclusive. It is my understanding there is a chance that life was indeed detected. The 1980s saw a nadir in Mars exploration, and then in 1996 it swung up with the ALH84001 meteoroid find and the Sojourner minirover. Now Mars is a "hot" planet, hot in terms of science, cold in climate, for the time being.
Mars appears to have freeze-dried up about a billion years after its formation. So conditions may well have been right for the pre-biotic chemistry leading to the development of living organisms. Whether life exists now is a question on the adaptability of life. It is entirely plausible that life has evolved in microbial forms to live in the soil (regolith?), and that martian biology might be an extensive ecosystem which lives below the surface and away from UV, and where it can catch some intermittent liquid water during a thaw.
I doubt Earth microbes can survive there. Of course bacteria can exist for long periods of time in a frozen state. However, if the cells go through any freeze-thaw cycling that might kill them off. If they are permanently frozen they might remain biologically capable, but in effect turned off.
We really can't know this for certain until there is a robotic probe largely dedicated to this task. A mobile lab bench dedicated to biological experiments, which should include microscopes to observe samples and results from test tubes with growth media, needs to be planted there to perform a range of tests on as wide a geography as possible. Until then we will be faced with a lot of “could be” and “maybe” claims and explanations, along with counterpoint “probably not” voices as well.
Cheers LC