Could Martian Bacteria Have Seeded Earth?

A new study of an ancient meteorite yields new clues to the origins of life

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A false-color cross-section of the Tissint meteorite.

If you were a passenger aboard the meteorite from Mars bearing down on the town of Tata, Morocco in July 2011, you would  be in a decidedly unenviable position. For one thing you’d be a bacterium — a nifty Martian bacterium, to be sure, but still. For another thing you’d be either freeze-dried or in a state of suspended animation — the better to survive the thousands or even millions of years you might have spent in space. And the odds are that even if you were alive and well when you stowed away on the rock while it was on Mars, the life would have been snuffed out of you the moment the asteroid hit that blasted you into space in the first place.

(Photos: Window on Infinity: Pictures from Space)

On the other hand, maybe you’d survive — maybe the shock would not have been so great or you’d be tucked away deep enough in the meteorite that you were spared its full power. And if you did survive and arrived on Earth a few billion years ago, maybe you’d have have adapted well to your new home and grown and thrived and served as the seed for every organism that ever populated your new planet including, eons later, the human species itself. In which case, modern humans never have to contemplate meeting Martians again because we are the Martians.

That, anyway, is the thinking behind panspermia — the theory that life on Earth may have come from beyond, if not bacteria from Mars, then organic raw materials from comets or asteroids that rained down on the planet back in the heavy bombardment days of the early solar system. It’s an idea that’s spawned a lot of faculty-lounge theorizing for more than a century, but in recent years, it’s attained a new credibility. Observations from both space-based and Earthbound telescopes as well as interplanetary probes have shown that organic chemistry is common everywhere in the cosmos. Space is rich in hydrocarbons, water and even the amino acids essential to life. Nucleobases, amino acids and  sugars have been found in meteors that have crashed to Earth. Our planet’s water itself  is thought by many scientists to have been imported to us aboard ice-heavy comets long ago, preparing the planet for the life it would one day support.

(More: Did a Distant Solar System Send Life to Earth?)

Panspermia is quietly becoming a go-to area of study for astronomers and astrobiologists, and a new paper published in the current edition of Science is a very good example of what the field is doing. A team of investigators got their hands on a few bits of that Moroccan meteorite — known as the Tissint meteorite for its mineral composition — and subjected it to both mineralogical and chemical analyses, and while no traces of bacteria were found (and none were expected to be found) the scientists did learn more about what it would take for such a planetary tissue exchange to occur.

Martian meteorites look like any other meteorite, but decades of samplings of the Mars’s air and soil by NASA probes have made it easy for scientists to match the chemistry of a space rock with the chemistry of the Red Planet — and the Tissint meteorite is a perfect fit. The debris the researchers studied has what’s known as a fusion crust, a black outer skin that was the result of the super-heating that occurred when the body entered Earth’s atmosphere. The interior is shot through with black glass veins that are rich in traces of Martian air. It’s the glass that makes the meteorite so improbably lovely — to geologists, at least — and also reveals the most about its past.

“You’ve got a rock sitting at the surface of Mars, the impact takes place and the shock wave passes through and kicks it up into space,” says Chris Herd, a meteorite expert at the University of Alberta and one of the co-authors of the paper. “But the shock wave can also cause very local melting where there are open fractures or cavities in the rock. That space collapses and it melts.”

(More: Space Discovery: Long Before Earth, Asteroids May Have Served as Incubators of Life)

That would be bad news for any Martian bacteria that happened to be aboard. “Where would you expect microorganisms to be?” asks Herd. “You’d expect them to be in the fractures. Maybe water percolates there. Maybe they set up shop there like organisms that live in rocks on Earth do. Those guys would be vaporized when the melt pockets form.”

That doesn’t stop scientists like Herd from looking for such signs of extraterrestrial life in meteorites both from Mars and elsewhere in space — nor should it. For one thing, just because some bacteria would be flash-cooked when the fragment takes off doesn’t mean all of them would; and some rocks, Herd points out, undergo less peak shock than others. The shortest transit time from Mars to Earth for a randomly drifting meteor would be about 10,000 years —  survivable for bacteria that can enter a state of self-protective suspended animation, which some bacteria on Earth do in harsh desert or polar climates. And while such a long time in interplanetary space exposes any organism to lethal  levels of cosmic radiation, at least one species of Earthly bacteria, known as Deinococcus radiodurans, has been found to shrug off even the most high-energy radiative roasting. “A lot has to go right,” for bacteria to make a planet-to-planet trip, Herd concedes, but it’s by no means an impossible scenario.

The idea that organics — or even organisms — drift from world to world like spores on the wind is an unfamiliar one for most people. But unfamiliar ideas have a way of becoming familiar, and even commonplace, quickly. The great, thriving terrarium that is Earth may be unique in our solar system. But if the new findings show anything, it’s that our planet may not be at all unique — or even terribly special — in the cosmos as a whole.

More: Alien Life Discovered in a Meteorite! Or Maybe Not

Photos: Snapshots of the Heavens: Amazing Astronomy Images

The full story in the new issue of Time is available here.

14 comments
Russell Seitz
Russell Seitz

If the 'we have met the Martians , and  us  is them' ' paradox sounds strangely familiar , it's because you read it in the WSJ seven years ago:

http://online.wsj.com/article/...

What ever was Jeff Kluger  reading in 2005 ?

Mike Birman
Mike Birman

Panspermia as a theory for life's diffusion has been around for awhile. What has given the theory new impetus is the discovery of complex organic molecules - including amino acids, the building blocks of proteins - in star nurseries like the Orion Nebula. That the molecular building blocks of life can be found drifting in the depths of space is highly suggestive. Life may very well be ubiquitous throughout the universe. Whether that life is intelligent remains to be seen. Some would argue that there is precious little intelligent life on Earth, but that might be a little harsh.

cristoforo
cristoforo

So maybe L. Ron was not that far off the mark?  (Aside from the "DC8" spaceships and nuclear volcanoes.)

bontemedical
bontemedical

While many see man as being on top of the food chain. "Bacteria Rule". Not only can one speculate they can travel inteplanetary in suspended animation but to handle heat and radiation is unheard of.

In regards to our own existence they are also in control. As we enter our earth as newborn the babies stomach is sterile and has to be propagated with the mothers intestinal flaura at the correct concentration so that proper digestive processes work correctly and diseases like crohns and collites and inflamatory bowel don't manifest themselves later on. Intestinal bacteria are key for proper immune response and nutrient uptake. I have a theory about incorrect concentrations of gut bacteria assisting in or helping develop autistic tendencies. Someday I hope this to be proven.

 

Dangerous bacteria that are antibiotic resistant can decimate a population if left to propagate such as flesh eating and staph found commonly in hospital environment.

When man is long gone and probably destroyed himself due to want and greed. Bacteria will still be here and the evolutionary cycle will start all over again.

Raimo Kangasniemi
Raimo Kangasniemi

Martian bacteria could have seeded Earth, or Venusian ones, or Earth could have seeded both of it's sister planets. It might be that during the first billion to one and half a billion years of the planets' existence life was swapped between the planets numerous times, so that emerging biospheres on them could have in effect been shared.

bellaluna30
bellaluna30

What is it with Mars lately?  The whole "blizzards on Mars" and "volcanoes on Mars" and now this.

cate c
cate c

This shows that scientists are just as in love with the "we're not smart enough to do it ourselves" club.   Sounds just like the UFO goofs who say we weren't smart enough to build the pyramids/stonehenge/printing press without the help of saucerpeople.  How sad.

Good and Godless
Good and Godless

L Ron was WAY off on his dates and further off on his mechanisms.

cjacja
cjacja

You might be right.  But because Mars cooled first life moved from it to Earth.  Mr have an environment suited to life first.

Raimo Kangasniemi
Raimo Kangasniemi

We have three orbiters and two rovers on Mars. Naturally they produce a wealth of new information on a steady basis, which leads to numerous new popular articles about the findings.

Moongu Kang
Moongu Kang

We aren't smart enough to give birth to ourselves? Damn us for being so stupidly dependent on a source of life that may not have existed on Earth. 

Raimo Kangasniemi
Raimo Kangasniemi

We know, thanks to a few surviving bits of zircon, that Earth had surface water already some 4.4 billion years ago. It's almost a certainty that Earth got big hits from asteroids after that until the end of Late Heavy Bombardment in 3.8 billion years ago, hits which were strong enough to melt Earth's whole surface. Life that would have risen 4.4 billion years ago could have survived only in deep underground or blasted to orbit inside rocks - some of which might have ended up on Venus and Mars instead of falling back to Earth or being stranded on solar orbit.