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NATURAL SCIENCE

Did astrobiologists find a space alien fossil? Probably not

A paper published by a team of astrobiologists claims to have found "fossilized biological structures" inside meteorite fragments.Wickramasinghe et al.

Forget hunting for organic chemistry inside rocks on Mars or complex organisms in Europa’s sub-surface oceans; the Cosmos has just FedEx’d some extraterrestrials direct to our door! Or, at least, that’s what a group of astrobiologists want us to believe.

Unfortunately (or fortunately, it depends how you spin it), the research — uploaded to the arXiv preprint service and published in the questionable Journal of Cosmology (JoC) — probably isn’t conclusive evidence of the existence of extraterrestrial biology. Bummer.

Frustratingly, it’s also an example of how science shouldn’t be done. But, by default, it’s also a fine example of how good, skeptical science writing should be done.

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To make a long story short, a paper published by a team of astrobiologists claims to have found “fossilized biological structures” inside meteorite fragments found after an apparent fireball over the North Central Province of Polonnaruwa, Sri Lanka, was seen on Dec. 29, 2012. This new publication appears to be based on the same samples that Chandra Wickramasinghe’s team analyzed and published results in January. In that publication, the researchers went all out, claiming: “The new data on ‘fossil’ diatoms provide strong evidence to support the theory of cometary panspermia.”

That research was heavily (and rightfully) criticized, not only for its baseless, extraordinary claims, but for the apparent poor scientific process and the fact no outside specialists were consulted before their work was published in the JoC. Oh, and there was a serious lack of some much-needed extraordinary evidence.

So, what’s different in this new paper? Well, there’s some funky analysis detailed, little of which will calm the skeptics.

It Probably DIDN’T Come from Outer Space?
According to the new publication (uploaded to the arXiv on March 6), there were many eyewitness accounts of the meteorite fall over Sri Lanka. “Police records indicate reports of low level-burn injuries from immediate contact with the fallen stones and subsequent reports of a strong aroma,” the authors write. “One woman was reported to have lost consciousness and was transported to the hospital after inhaling fumes from one of the stones.”

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If you think this is sounding like the opening scene to an adaptation of “Invasion of the Body Snatchers,” you’re not alone.

For starters, contrary to common belief, meteorite fragments are usually cool when they reach the ground. Sure, the space rock undergoes heating during entry through the atmosphere — when it generates a bright meteor caused by rapid pressure heating of the atmospheric gas in front of the meteor — but it’s not enough to heat a lump of rock that has been frozen to near absolute zero in deep space. Rocky meteorites are poor conductors of heat, so any heating that occurs during the few seconds of flight through the atmosphere chars and ablates the outside (creating an often smooth crust — called a fusion crust), but leaves the inside cold. In the case of a fireball that breaks up in the atmosphere, the fragments will fall at terminal velocity (i.e. much slower than the meteor), cooling even further before landing.

Therefore, I find it hard to believe that any burn injuries occurred due to recently fallen meteorite fragments. (Memories of the Tel Aviv “meteorite” that behaved more like an incendiary device come flooding back.) As for the “strong aroma” and stones that produced “fumes” that rendered a woman unconscious, it is hard to see how a meteorite would have caused that. Perhaps the meteorite fragments hit a septic tank? That might explain it. Unless it’s some kind of rudimentary alien invasion tactic? Who knows.

Already we’re on shaky ground. The event that allegedly accounted for the meteorite fragments delivered to Wickramasinghe’s team’s labs is based on a pretty strange series of events.

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And then there’s the meteorite fragments themselves. 628 fragments were collected from a large 10 kilometer-wide rice field fall zone, of which only three were positively identified by the team as originating from space. One sample is shown here.

But there’s a problem… that doesn’t look like a meteorite. It’s kinda porous. And jagged-looking. It’s crumbling a bit, too.

Usually meteorites are dense, smooth, dark rocks with a tell-tail fusion crust. Even fragments from a parent fireball don’t look like that. But it’s OK! They measured the oxygen isotopes contained within the samples to confirm “unequivocally” the ratios match that of known space rocks.

Sadly, as Bad Astronomer Phil Plait points out, there’s no mention on how the team avoided carbonate contamination of the sample — contamination that can throw oxygen isotope measurements. “But even if they had (carried out the correct procedure), the non-standard oxygen isotope ratio is not proof of extraterrestriality, it just isn’t necessarily inconsistent with it. So really, their claim that the isotope ratio proves ‘unequivocally’ these are meteorites is wrong, plain and simple.” So there’s every chance that either the rocks are meteorites (but they were contaminated) or they are, you know, rocks. As in rocky rocks; rocks that came from the ground (on Earth).

Planet-Hopping Life?
Now… about those “aliens,” that, interestingly, are never referred to as such in the publication. Remarkably well-preserved “fossils” (pictured top) of alleged diatoms that have allegedly been found inside the samples of alleged meteorite samples. Diatoms are a type of algae. Needless to say, the discovery of this type biology inside a meteorite would be historic. Unfortunately, despite the researchers’ claims to the contrary, they are likely contamination.

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“Wickramasinghe’s team claims they found diatoms deep inside the samples, and therefore can’t be contaminated,” wrote Plait. “But this is incorrect. I’ve talked to biologists who look for life in rocks, and they say that contamination is a huge problem. These buggers are small and can find their ways into the smallest cracks and fissures.” Also, as these “meteorite” fragments fell in a rice field — known to be a pretty wet place — contamination with Sri Lankan algae would probably be the most likely explanation.

At first glance, the research seems genuine, but after a little reading, it becomes clear that the correct procedure has not been carried out. Also, the fact that experts in the fields of meteorites and diatoms were not consulted is another red flag. This is not peer-reviewed science. Add all this to the fact that none of this work was published in a mainstream journal should be a warning that the extraordinary conclusions are baseless.

The hypothesis that life was seeded by hitchhiking microbes inside space rocks from planet to planet — known as panspermia — is grounded in real science, however. But there is currently no evidence supporting the hypothesis, so far. Personally, I think the hypothesis makes a whole lot of sense, but until we have real evidence to support this idea, it will remain a hypothesis, nothing more.

It is my concern that knee-jerk studies such as this and the inevitable tabloid headlines they produce cheapen the genuine science being done by astrobiologists. The search for extraterrestrial life, and potential transfer mechanisms like panspermia, is one of the most profound hunts of our time — in fact, of any time. It is critical that the scientific due diligence is done before claims of extraterrestrial biology is even hinted at.