For much of Earth’s four & a half billion years, the earth was deserted and inhospitable; it wasn’t until the planet acquired its blanket of oxygen that multicellular life could really keep going. But scientists are still trying to know exactly how and why our planet got this delightful oxygenated atmosphere.
“If you little think about it, this is very important change that our planet experienced in its lifetime and we are still not sure exactly how this happened” said Nicolas Dauphas, Louis Block Professor of Geophysical Sciences at University of Chicago. “Any progress you make toward answering this question is basically important.”
In new study, UChicago graduate student Andy Heard, Dauphas & their colleagues used a pioneering-technique to uncover new information about the role of oceanic iron with the rise of Earth’s atmosphere. The findings reveal much more about Earth’s history and even shed light on the look for habitable planets in other star systems.
Scientists have painstakingly recreated a timeline of the early Earth by analyzing ancient rocks; chemical makeup of such rocks changes consistent-with the conditions they formed under.
“Interesting thing about it’s that before the permanent Great Oxygenation Event that happened 2.4 billion years ago, you spot evidence within the timeline for these tantalizing little bursts of oxygen, where it’s look like Earth was trying to fix the stage for this atmosphere” said Heard, the first author on the paper. “But prevailing methods weren’t precise enough to tease out the knowledge we would have required.”
It all comes right down to a puzzle.
As bridge-engineers and car-owners know, if there’s water around, oxygen & iron will form rust. “In early days, the oceans were filled with iron, which have gobbled up any free oxygen that was hanging around” Heard said. Theoretically, the formation of rust consume excess oxygen, leaving-none to form an atmosphere.
Heard & Dauphas wanted to check a method to explain how oxygen could have accumulated despite this apparent problem: they knew that a number of the iron within the oceans was actually combining with Sulphur coming-out of volcanoes to make pyrite (better referred to as fool’s gold). This process actually releases oxygen into the atmosphere. The question still was which of those processes “wins.”
To test it, Heard used state of art facilities in Dauphas’ Origins Lab to develop a rigorous new technique to calculate tiny variations in iron isotopes so as to find out which route the iron was taking. Collaborating with the world experts at University of Edinburgh, he also had to flesh out a fuller-understanding of how the iron to pyrite pathway works. (“So as to form Sulphide and run all these experiments, you require understanding colleagues because you create labs smell like rotten eggs” Heard said.). Then, the scientists used the technique to research 2.6 – 2.3 billion year old rocks from Australia & South-Africa.
Their analysis revealed that, even in oceans that ought to have tucked away tons of oxygen into rust, certain conditions have fostered the formation of enough pyrite to permit oxygen to flee the water and potentially form atmosphere.
“It’s a sophisticated problem with many moving parts but we’ve been ready to solve one a part of it,” said Dauphas.
“Progress on situation, this enormous is basically valuable to community” Heard said. “Especially as we’re starting to search for exoplanets, we actually understand every detail about how our earth became habitable.”
As telescopes scan skies of other planets and find thousands, scientists will narrow down which to explore further for potential life. By learning more about the way that how our Earth became habitable, they will search for evidence of comparable processes on other planets.