May 20, 2009

Asteroids may have aided life on Earth

A U.S. space agency-funded study suggests an intense asteroid bombardment nearly 4 billion years ago might have provided a boost for early life on Earth.

The National Aeronautics and Space Administration said the research suggests the asteroids might not have sterilized the early Earth as completely as previously thought.

The study focused on a particularly cataclysmic occurrence known as the Late Heavy Bombardment, or LHB, NASA said. This event occurred approximately 3.9 billion years ago and lasted 20 to 200 million years.

The researchers -- University of Colorado astrobiologists Oleg Abramov and Stephen Mojzsis -- said they conducted a computer modeling project designed to study the heating of Earth by the bombardment.

The results show that while the Late Heavy Bombardment might have generated enough heat to sterilize Earth's surface, microbial life in subsurface and underwater environments most likely would have survived.

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

Abramov said the results also support the potential for the persistence of microbial biospheres on other planetary bodies with surfaces reworked by the bombardment, including Mars.

The study is reported in a letter published in Nature magazine.