Meteor impacts: Life's jump starter?

Aug 08, 2005

Meteor impacts are generally regarded as monstrous killers and one of the causes of mass extinctions throughout the history of life. But there is a chance the heavy bombardment of Earth by meteors during the planet's youth actually spurred early life on our planet, say Canadian geologists.

A study of the Haughton Impact Crater on Devon Island, in the Canadian Arctic, has revealed some very life-friendly features at ground zero. These include hydrothermal systems, blasted rocks that are easier for microbes to inhabit, plus the cozy, protected basin created by the crater itself. If true, impact craters could represent some of the best sites to look for signs of past or present life on Mars and other planets.

A presentation on the biological effects of impacts is scheduled for Monday, 8 August, at Earth System Processes 2, a meeting co-convened by the Geological Society of America and Geological Association of Canada this week in Calgary, Alberta, Canada.

The idea that meteor impacts could benefit or even create conditions suitable for the beginning of early life struck Canadian Space Agency geologist Gordon Osinski while he and colleagues were conducting a geological survey of the 24-kilometer (15-mile) diameter Haughton Crater. Along the rim of the crater they noticed what looked like fossilized hydrothermal pipes, a few meters in diameter.

"That set the bells ringing about possible biological implications," said Osinski. Hydrothermal systems are thought by many people to be the favourable places for life to evolve."

Detailed mineralogical analyses have since revealed that when the Haughton meteor smacked into the icy ground 23 million years ago it created not only a crater, but fractured the ground in such a way as to create a system of steamy hydrothermal springs reaching temperatures of 250 degrees C. The heat appears to have gradually dropped over a period of tens of thousands of years, the researchers report.

Besides providing heat and cracking the ground, the impact also created pore spaces in otherwise dense granitic rocks, giving microbes more access to the minerals and the surfaces inside the rocks - basically more real estate and more supplies.

The shocked rocks are also more translucent, which would be beneficial to organisms that possessing with any photosynthetic capabilities.

A crater shape itself also might serve as a protective environment, says Osinski. As such, impact craters are also good places to store evidence of past life. On Earth many craters fill with water and become lakes. Lakes accumulate sediments, the layers of which are a geological archive of the time after the crater formed. The Haughton Impact crater, for instance, contains the only Miocene-age sediments in the entire Canadian Arctic.

"One of the most interesting aspects of the Haughton Impact Crater is that it's in a polar desert," said Osinski. The dry, frigid weather makes for a barren landscape that's easy to study, he said. The same features make it one of the more Mars-like places on Earth.

"Most people put impacts with mass extinctions," said Osinski. "What we're trying to say is that following the impact, the impact sites are actually more favorable to life than the surrounding terrain."

It's interesting to note, says Osinski, that on Earth the heaviest meteor bombardment of the planet happened at about the same time as life is believed to have started: around 3.8 billion years ago. Impact craters of that age were long ago erased on Earth by erosion, volcanic resurfacing and plate tectonics.

But other planets and moons - including Mars - still bear the cosmic scars of that early debris-clogged period in the solar system. It may be possible, therefore, that the best places to look for at least fossil evidence of life on Mars is inside those very same craters, he said.

"What we're doing is trying to narrow down the search area," said Osinski.

Source: Geological Society of America

Explore further: Greenland darkening to continue, predicts CCNY expert Marco Tedesco

Related Stories

The solar system and beyond is awash in water

Apr 08, 2015

As NASA missions explore our solar system and search for new worlds, they are finding water in surprising places. Water is but one piece of our search for habitable planets and life beyond Earth, yet it links ...

World's largest asteroid impact site could be in Australia

Apr 07, 2015

Not long ago, asteroid impacts weren't considered as a significant factor in the evolution of Earth. Following the Late Heavy Bombardment, which pummelled the inner solar system around 3.8 billion to 3.9 billion ye ...

The pale blue dot and other 'selfies' of Earth

Apr 06, 2015

Twenty-five years ago a set of images were taken that provided a unique view of Earth and helped highlight the fragility of our existence, and the importance of our stewardship.

Recommended for you

A blueprint for clearing the skies of space debris

Apr 17, 2015

An international team of scientists have put forward a blueprint for a purely space-based system to solve the growing problem of space debris. The proposal, published in Acta Astronautica, combines a super-wide field-of-view telesc ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.