- A massive impact with a giant asteroid could have kick-started
life on Earth more than four billion years ago by providing an ideal environment
for incubating the world's first lifeform.
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- Scientists studying an impact crater in the Arctic have
found evidence to suggest that asteroids hitting the Earth can help life
to flourish as well as cause catastrophic destruction.
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- Charles Cockell, of the British Antarctic Survey in Cambridge,
said analysis of rocks in the Haughton impact crater on Devon Island, Nunavut
Territory, Canada, has shown how asteroids can help life to flourish.
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- The intense heat of an asteroid impact causes rock minerals
to vapourise, leaving tiny cracks and crevices inside the rock where microbes
can live.
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- "We've discovered that rocks inside the crater are
more heavily colonised by microbes than the rocks outside the crater,"
Dr Cockell told the British Association Festival of Science being held
in Exeter.
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- "So what we have here is an example of how impact
events can create a habitat for life and not merely act as agents of destruction,"
he said.
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- The Haughton crater was created 25 million years ago
when an asteroid about a kilometre wide hit Earth, releasing energy equivalent
to about 1,000 Hiroshima atomic bombs.
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- "When they hit the ground most of the energy is
released as heat and one of the effects of that is to provide the energy
for simple organic compounds to form more complex compounds," Dr Cockell
said.
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- The heat from a similar impact about four billion years
ago could have lasted for between 1,000 and a million years. This may have
kept any water collecting within the crater at a constant warm temperature,
providing an ideal environment for the origins of life.
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- "It is one of the rare instances where asteroids
and comets could actually be good for life," Dr Cockell said.
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- "There's a growing feeling that as well as being
beneficial in terms of habitat, impact events can also improve conditions
for the evolution of life in the first place. As well as telling us something
about evolution on Earth, these impact craters may be relevant for the
search for life elsewhere," he added.
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- Meanwhile, methane gas has been found on Mars. The only
explanation for the gas is undiscovered volcanic activity or primitive
underground life, Andrew Coates, a British scientist at the Mullard Space
Science Laboratory, told the Festival of Science yesterday.
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