Insights into the origin of carbonaceous chondrite organics from their triple oxygen isotope composition
Authors: Romain Tartèse, Marc Chaussidon, Andrey Gurenko, Frédéric Delarue, François Robert
Journal: Proceedings of the National Academy of Sciences of the United States of America
Publication Date: 06 August, 2018
Department of: Earth and Environmental Sciences
Investigating organic matter from asteroids to comprehend how and where the building blocks for life formed
Organic matter found in volatile-rich asteroidal materials is made of the elements C, H, O, N and S, which are thought to be important building blocks for life. Characterising the origin(s) of these organics thus constitutes a key step to constrain the origin of life on Earth, and appraise the habitability potential of other worlds in the Universe. Yet how and where these organics formed is still highly debated. To tackle this issue, researchers from The University of Manchester and collaborators in France used secondary ion mass spectrometry to precisely measure the oxygen isotope composition of refractory organics from two types of carbonaceous chondrites. Their results suggest that the bulk of carbonaceous chondrite organics formed in the nascent Solar System, possibly through chemical reactions occurring in the disk surrounding the young Sun, rather than in response to low temperature fluid circulations on asteroidal bodies. These findings suggest that if organic materials can form through simple chemical processes operating in our Solar System, it is likely that they are widespread in other planetary systems.
- Meteorites that fall onto the Earth comprise fragments of asteroids, which are left-over from the planet-forming epoch 4.5 billion years ago. Their study is thus key to investigate how planetary bodies of the Solar System formed and evolved.
- Some meteorites belonging to the carbonaceous chondrite family contain abundant organic materials rich in C, H and N, elements that are crucial for life as we know it. Impacts of organic-rich asteroids to the Earth around 4 billion years ago may have thus delivered prebiotic organic molecules from which life arose.
- How and where organic matter found in meteorites formed remains a mystery. Three main hypothesise exist: (i) organics are inherited from the interstellar medium; (ii) organics formed on asteroids in response to water percolation through rocky layers; (iii) organics synthesis occurred through irradiation of carbon-rich gas around the young Sun.
- The isotopic composition of oxygen measured in carbonaceous chondrite organics in this study suggests that these organics formed in the gas nebula around the young Sun.