As much you, I, and most people may have a special dark place in our heart for the dust we are forever having to clean, dust in space is actually a really good thing. In a pair of new papers appearing in Science Advances, researchers have been able to track how carbon dust goes from the clouds of space to be an integral part of life on Earth. 

According to researcher Marc Hirschmann, lead author of one of the two papers: Most models have the carbon and other life-essential materials such as water and nitrogen going from the nebula into primitive rocky bodies, and these are then delivered to growing planets such as Earth or Mars. But this skips a key step, in which the planetesimals lose much of their carbon before they accrete to the planets. 

Put another way, we imagine these great clouds of material collapsing to form a star and its surrounding planets, and this is likely true, but we have to remember those forming planets and the stuff they form from is all baked by the young sun. Some materials, including carbon and water, get blasted off. To get to worlds like Earth, rich in carbon, the team assumed the carbon had to be locked away in the cores of these forming worlds – worlds like Earth – where it couldn’t be blown away. The lead author of the second paper, Jackie Li, puts it this way: We asked how much carbon could you stuff in the Earth’s core and still be consistent with all the constraints.

These studies found that worlds really need to start with a lot of carbon to get to keep enough carbon to eventually support life. Sure, meteors and comets that formed farther from the Sun will bring us some of the carbon we need, but it may be that to get a world with a carbon cycle that supports life, you really need to start with planet-forming objects that hide their carbon in their cores.

More Information

University of Michigan press release

“Earth’s carbon deficit caused by early loss through irreversible sublimation,” J. Li, 2021 April 2, Science Advances