MagazineSci-fi news

Just in | Library of scifi news

Share

Asteroids giveth, and asteroids taketh away

25/05/2009. Contributed by Jessica Martin

author pic

A mega asteroid bombardment four billion years ago may not have sterilised the early Earth as completely as previously thought. In fact, the asteroids, some the size of Kansas, provided a boost for early life. Go figure, ELE fans.

The NASA-funded study focused on a particularly cataclysmic occurrence known as the Late Heavy Bombardment, or LHB. This event occurred approximately 3.9 billion years ago and lasted 20 to 200 million years. In a letter published in the May 21 issue of Nature magazine titled Microbial Habitability of the Hadean Earth during the Late Heavy Bombardment, Oleg Abramov and Stephen J. Mojzsis, astrobiologists at the University of Colorado's Department of Geological Sciences, report on the results of a computer modelling project designed to study the heating of Earth by the bombardment.



Results from their project show that while the Late Heavy Bombardment might have generated enough heat to sterilise Earth's surface, microbial life in subsurface and underwater environments almost certainly would have survived.

Michael H. New, the astrobiology discipline scientist and manager of the Exobiology and Evolutionary Biology Program at NASA Headquarters in Washington told SFcrowsnest, "Exactly when life originated on Earth is a hotly debated topic. These findings are significant because they indicate that if life had begun before the LHB or some time prior to 4 billion years ago, it could have survived in limited refuges and then expanded to fill our world."

"Our new results point to the possibility life could have emerged about the same time that evidence for our planet's oceans first appears," added Mojzsis, principal investigator of the project.

A growing scientific consensus is that during our solar system's formation, planetary bodies were pummelled by debris throughout the Late Heavy Bombardment. A visual record of the event is preserved in the form of the scarred face of our moon. On Earth, all traces of the bombardment appear to have been erased by rock recycling forces like weathering, volcanoes or other conditions that cause the crust to move or change.

Surface habitats for microbial life on early Earth would have been destroyed repeatedly by the bombardment. However, at the same time, impacts could have created subsurface habitats for life, such as extensive networks of cracks or even hydrothermal vents. Any existing microbial life on Earth could have found refuge in these habitats. If life had not yet emerged on Earth by the time of the bombardment, these new subsurface environments could have been the place where terrestrial life emerged.

Abramov, lead author of the paper, concluded, "Even under the most extreme conditions we imposed on our model, the bombardment could not have sterilised Earth completely. Our results are in line with the scientific consensus that hyperthermophilic, or 'heat-loving,' microbes could have been the earliest life forms on Earth, or survivors from an even more ancient biosphere. The results also support the potential for the persistence of microbial biospheres on other planetary bodies whose surfaces were reworked by the bombardment, including Mars."

Magazine > Scifi news

Just in | Library of sci-fi news

Add SFcrowsnest.com daily news updates to your own web site or blog - just cut and paste the code below...

Share

The all-new SFcrowsnest is now running at www.SFcrowsnest.org.uk. This is now the archive for pre-2012 content. Nothing new is being posted here.

Magazine Articles

- Features

- Movie/TV Reviews

- Book Reviews

- News

- E-mail magazine

- Encyclopedia

- Other formats: Kindle, Nook, Sony Ebook, iPhone & iPod

Charts

- Top books

- Top movies/tv series

Offworld

- SciFi @ FaceBook

- Steampunk @ FaceBook

- Us @ Google+

Search

- Search site

Reader Tools

- RSS news feed

- Facebook page for SFcrowsnest

- Twitter page for SFcrowsnest

- Google toolbar for SFcrowsnest

Webmaster Tools

- Add our content feeds to your site