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Posted on 09/12/2008 6:29:45 PM PDT by LibWhacker
The idea that life on Earth might have originated elsewhere, on Mars, for example, has gained currency in recent times as we’ve learned more about the transfer of materials between planets. Mars cooled before the Earth and may well have become habitable at a time when our planet was not. There seems nothing particularly outrageous in the idea that dormant bacteria inside chunks of the Martian surface, blasted into space by comet or asteroid impacts, might have crossed the interplanetary gulf and given rise to life here.
But what of an interstellar origin for life on Earth? The odds on meteoroids from a system around the average galactic field star not only striking the early Earth but delivering viable microbes are long indeed. But if we consider the Sun’s probable origin in a cluster of young stars, all emerging from the same collapsing cloud, the picture changes significantly.
Now we’re dealing with much smaller distances between stars and slow relative motion as well, conditions that could make such a transfer possible. A new paper makes the case that this process might well have been two-way:
…there is a definite possibility that bacteria carrying meteoroids of extrasolar origin have landed on the Earth. In reverse, it is possible that at least one other planetary system in our birth star cluster received a life-carrying asteroid from the Earth; and it is not excluded that the whole birth star cluster was ‘fertilized’ in this way by live bacteria from the Earth.So write Mauri Valtonen (Turku University, Finland) and team in an upcoming paper. The authors believe bacterial exchanges between planets of different solar systems could only have occurred during the birth cluster stage of these systems, but given this constraint, it is possible that the Earth received large numbers of life-bearing bodies early on. The broad process of panspermia in which life spreads through an entire galaxy from a single source seems unlikely, but “…life-carrying bodies originating from our solar system may have found their way to our original neighbours, and …all conditions being optimal, life seeded by our system could have spread to many other solar systems.”
And now it gets interesting for future space missions. Because we may be getting into position to find our long lost relatives, the stars from the original cluster that gave birth to our Sun. They’ve long since moved away from us, but missions like Gaia may be able to track them down. Gaia will study a billion stars in the Milky Way, monitoring each some seventy times over the course of a five year period. The mission is expected to discover extrasolar planets, brown dwarfs and numerous other interesting objects, and will help us extend our picture of galactic structure three-dimensionally, perhaps pin-pointing our siblings.
Gaia is expected to be launched in 2011, a much improved version of the Hipparcos mission that did so much to catalog the more than 100,000 stars it looked at. It’s a significant upgrade, and other missions to be launched within the next two decades could go on to provide us with a look at planetary systems around the stars Gaia identifies as members of our original stellar family. If we ever confirm the existence of life on these planets, we may be looking at worlds that either gave birth to life here or received life’s impetus from Earth.
The paper is Valtonen et al., “Natural Transfer of Viable Microbes in Space from Planets in the Extra-Solar Systems to a Planet in our Solar System and Vice-Versa,” accepted by the Astrophysical Journal and available online.
Should be trillions of them in just this galaxy.
I’ve heard stories that even in the 1920’s, some scientists speculated that our origins could have come from Mars and I managed to find one article about it in a Popular Science or Mechanics magazine from 1933 where a meteor came down and there were microscopic life forms on it.
Pinging SunkenCiv...
I seen it in a comic book.
ok... yeah... life on Earth came from Mars - a dead planet with NO sign of ANYTHING on it... no fossils, no bones, no sign of ANY civilization...
But we all originated on Mars... Not Venus, Not Jupiter... okey dokey...
Anybody looking to purchase a bridge? I got one for sale.
PANSPERMIA!!!
Nice try guys, but no cigar!
1933? Really? The first meteorite about which such a claim was made AFAIK was, hmm, maybe it’s time to look this up again...
Evidence of Ancient Martian Life in Meteorite ALH84001?
http://nssdc.gsfc.nasa.gov/planetary/marslife.html
Okay, this is more like it, 1984, discovered in Antarctica, struck the Earth 13,000 years ago, left Mars for its trip 16 million years ago, etc. But anyway, regardless, please post that article you found, it has to be interesting!
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Superman made such a voyage.
It is plausible that a dying intelligence somewhere did in fact blast a life containing capsule into space. Speculation as to what life forms were in the capsule can be endless. That could have been Mars or from outside our system.
The tale of the Burgess shale is very interesting in the story of multitudes of living experiments that flourished and died. The change from then to now is massive
That reminds me. Are we absolutely sure Dennis Kucinich is a native-born earthling?
Just a re-hash of the pan-spermia theory.
As I recall, this theory of panspermia was originally proposed by Arrhenius [spelling?] around 1900.
Rather than answering anything, it just begs the question.
Kind of like answering, “from Daddy,” when asked, “where does money come from?”
According to Wikipedia the idea goes back to the Greeks though.
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