Article: Earth sows its seeds in space



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Robert Karl Sto

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Earth sows its seeds in space Life could be leaking out all over the cosmos. 23 February 2004
PHILIP BALL

The Earth could be scattering the seeds of life throughout our Galaxy. Microbes could ride on specks
of dust, powered by the Sun's rays, says William Napier, an astronomer at the Armagh Observatory in
Northern Ireland.

Scientists have pondered whether life might ride between star systems ever since the nineteenth
century. Some think that a collision between a life-bearing planet and another celestial body could
scatter stones and boulders into space carrying living organisms. These deep-frozen spores could
then make their way to other worlds - an idea called 'panspermia'.

But the chances are stacked against such an event. Spores would have to survive the meteor impact
and be thrown into space. The boulder would then have to leave the solar system and land on another
life-supporting planet. It would have to get there quickly, too. The radiation streaming through
space will cook any organisms in space rocks. Typically, says Napier, "the boulders will be sterile
by the time they are ejected from the solar system".

But microbes might survive if they can escape the Sun's gravity more quickly. And that might happen,
says Napier, if the rocks they sit on are first ground to dust1.

The Earth and her sister planets travel through a cloud of grains called zodiacal dust. This is the
debris from collisions in the asteroid belt and from the passage of comets.

This dust should sand-blast anything passing through it, says Napier. This process could grind a one-
metre boulder down in 20,000-200,000 years, he estimates. If a comet breaks up, thickening the dust,
as happens several times each million years, the process could take as little as five centuries.

Read the rest at Nature http://www.nature.com/nsu/040216/040216-20.html

Posted by Robert Karl Stonjek.
 
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Red Dragon

Guest
"TomHendricks474" <[email protected]> wrote in message
news:[email protected]...
> The 'seeds' also have to survive re entry.

Not necessary. If the medium is a speck of dust, then it will just float down and re entry will be
no problem. Some scientist think that the recent SARS virus and the recent Bird Flu virus could have
their origin from space dust.

Khoon.
 
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Tim Tyler

Guest
Red Dragon <[email protected]> wrote or quoted:
> "TomHendricks474" <[email protected]> wrote in message

> > The 'seeds' also have to survive re entry.
>
> Not necessary. If the medium is a speck of dust, then it will just float down and re entry will be
> no problem.

Presumably the same "solar sail" process that was suggested could accelerate them could also
decelerate them again.

> Some scientist think that the recent SARS virus and the recent Bird Flu virus could have their
> origin from space dust.

You are /sure/ they were't talking about the mutagenic effect of cosmic rays? ;-)
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