Space Pebbles

World’s oldest space pebbles challenge accepted knowledge on the presence of oxygen on Earth billion years ago.

16:40 16 May 2016

A team of scientists has discovered tiny meteorites, which are 2.7 billion years old, suggesting the presence of oxygen on Earth during their time. The Australian team from Monash University’s School of Earth, Atmosphere and Environment found that the pieces were made of metallic iron that had been oxidized in the Earth’s atmosphere.

 

The findings, which were published in the journal Nature, challenge accepted geological belief that Earth did not have plenty of oxygen supply 2.7 billion years ago. It has been thought that the atmosphere’s lower layers was without oxygen, while the upper atmosphere, between 31 and 62 miles, was rife from oxygen and carbon monoxide as solar radiation broke down carbon dioxide molecules.

 

The micrometeorites, which are no bigger than grains of sand, are almost a billion years older than any previous samples and have been preserved in limestone in Western Australia. Researchers suggest that the space pebbles contain 10 times more oxygen than they should based on previous predictions.

 

Astrobiologist Timothy Lyons of the University of California, Riverside said: "These guys have possibly shown us that there might be a lot of oxygen that has nothing to do with what we’re looking for - the presence of life producing that oxygen."