[meteorite-list] Did Earth Seed Life Elsewhere in the Solar System?

From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Sat Mar 18 11:26:09 2006
Message-ID: <004401c64a2c$01e10b60$aceb8c46_at_ATARIENGINE>

Hi,

    Panspermia in reverse?
> Jeff Moore [says] "Once one planet comes down with life,
> they all get it."

    Reminds me of a cartoon I saw over 20 years ago (and taped
to my refrigerator until it fell apart) of an anthromorphised Mars
saying to an anthromorphised Earth, "I don't how to tell you
this, but you've got some kind of parasite on you..."

    If, in the Gladman simulation, 30 Earth rocks get to Titan in
5 million simulated years, that's 6 Earth rocks per million years.
Over the life of the solar system, that's 27,000 microbe bearing
Earth rocks for the Titan environment. Makes it sound like a
favored holiday destination of Earthly microbes...

    Interestingly, Freeman Dyson wrote an article in the Atlantic
Monthly (Nov, 1997) "Warm-Blooded Plants and Freeze-Dried
Fish," which used to be viewable on-line and now is not without
payment. I quote some of it:

    "Every time a major impact occurs on Europa, a vast quantity
of water is splashed from the ocean into the space around
Jupiter. Some of the water evaporates, and some condenses
into snow. Creatures living in the water far enough from the
impact have a chance of being splashed into space and quickly
freeze-dried. Therefore, an easy way to look for evidence of
life in Europa's ocean is to look for freeze-dried fish in
the ring of space debris orbiting Jupiter."

    And perhaps some of the impact splash escapes Jupiter
orbit altogether? Heading which way?

    I wish Gladman had modeled the reverse case. What are
the odds of something splashed up out of Europa arriving on
Earth? I'm remembering Ron Baalke's recent post of the article
on "Weird Rains" with its falls of fish, alligators and cows. Any
falls of ALIEN fish? Would anyone even recognize an Europan
fish as alien? Some of the things that are found in Earth's oceans
look pretty alien to me, like benthic fishes. "Excuse me, but...
you're not from around here, are you?"


Sterling K. Webb
-------------------------------------------------------------
----- Original Message -----
From: "Ron Baalke" <baalke_at_zagami.jpl.nasa.gov>
To: "Meteorite Mailing List" <meteorite-list_at_meteoritecentral.com>
Sent: Friday, March 17, 2006 1:03 PM
Subject: [meteorite-list] Did Earth Seed Life Elsewhere in the Solar System?


>
> http://www.nature.com/news/2006/060313/full/060313-18.html
>
> Did Earth seed life elsewhere in the Solar System?
>
> Impacts on our planet could have sprayed life into space.
>
> Mark Peplow
> nature.com
> March 17, 2006
>
> Earthly bacteria could have reached distant planets and moons after
> being flung into space by massive meteorite impacts, scientists suggest.
>
> The proposal neatly reverses the panspermia theory, which suggests that
> life on Earth was seeded by microbes on comets or meteorites from
> elsewhere.
>
> Both theories envision life spreading through the Solar System in much
> the same way that germs race around a crowded classroom, says Jeff
> Moore, a planetary scientist at NASA's Ames Research Center in Moffett
> Field, California. "Once one planet comes down with life, they all get
> it."
>
> Spreading germs
>
> Impacts on Mars and the Moon are known to throw rocks into space that
> end up on Earth as small meteorites. But spraying Earth rocks towards
> the edges of the Solar System is more difficult, because the material
> has to move away from the Sun's strong gravity.
>
> To find out just how many rocks could reach the outer Solar System, a
> team of scientists used a computer model to track millions of fragments
> ejected by a simulated massive impact, such as the one that created the
> Chicxulub crater some 65 million years ago. Similar sized events are
> thought to have happened a few times in Earth's history.
>
> The researchers looked in part at how many Earthly fragments would reach
> environments thought to be relatively well suited to life, such as
> Saturn's moon Titan and Jupiter's moon Europa. "I assumed the answer
> would be very, very few," says Brett Gladman, a planetary scientist at
> the University of British Columbia, Vancouver, Canada, who led the team.
>
> But Gladman was surprised to find that within 5 million years, about 100
> objects would hit Europa, while Titan gets roughly 30 hits. He presented
> the results at the Lunar and Planetary Science Conference in League
> City, Texas, on 16 March.
>
> Tough journey
>
> But could bacteria survive the sudden heat and acceleration of being
> thrown into space?
>
> Other researchers at the conference suggest that they can. Wayne
> Nicholson, a microbiologist from the University of Florida in
> Gainesville, has tested the idea with a gun the size of a house at
> NASA's Ames Research Center.
>
> He and his colleagues fired a marble-sized pellet at about 5 kilometres
> per second into a plate that contained bacterial spores in water, in
> order to simulate a meteorite impact. The debris that scattered upwards
> was caught in sheets of foam, and the team found that about one in
> 10,000 bacteria survived. "It's an experimental validation of a fairly
> well established calculation," says Moore.
>
> Crash landing
>
> Many astrobiologists believe that bacteria, once in space, could survive
> cosmic-radiation exposure during their trip. Unfortunately, a crash
> landing on Europa would almost certainly sterilize the few rocks that
> made it that far.
>
> "But Titan is a different story," says Gladman. The moon's thick
> atmosphere would first shatter the meteorite before slowing the
> fragments down; the same process happens with meteorite impacts on
> Earth. "It's a nice safety net," Gladman says. The heat of landing could
> even melt the ice and open up a short-lived pool of liquid for the
> visitors, he adds.
>
> At the conference, Gladman was asked whether, assuming a few bugs did
> make it safely on to Titan's surface, they could ever really thrive in
> the moon's chilly climes of about -170?C. "That's for you guys to work
> out," he told the audience. "I'm just the delivery boy."
>
Received on Fri 17 Mar 2006 08:33:49 PM PST