Analysis of old moon rocks has turned up a special type of carbon that could only come from a massive meteor impact 3.8 billion years ago. The Moon has preserved an essential record of what helped life on Earth begin.
There isn't much carbon on the Moon, and until now scientists had assumed it had all been brought there by the solar wind. But analysis of old rocks from the Apollo missions has revealed an unusual form of carbon known as a graphite whisker hidden inside. This is a big deal because graphite whiskers can only form in extremely high temperature reactions - anywhere between 1830 and 6500 degrees Fahrenheit - and such temperatures can only be reached during the chaotic upheaval of a meteor impact.
The Carnegie Institution's Andrew Steele explains what his team was hoping to discover:
"The Solar System was chaotic with countless colliding objects 3.8 billion years ago. Volatiles-compounds like water and elements like carbon were vaporized under that heat and shock. These materials were critical to the creation of life on Earth. Our team analyzed Moon rocks collected from the Mare Serenitatis impact crater visited by the Apollo 17 mission. In the past, researchers tried to extract the carbon from Moon material, but the only carbon definitively identified came from the solar wind. We used a different technique...We were really surprised at the discovery of graphite and graphite whiskers, we were not expecting to see anything like this."
The graphite whiskers are the remains of the late heavy bombardment era that occurred 3.8 billion years ago, and whatever hit the Moon most definitely hit the Earth as well. Ancient meteors are thought to have contributed some of the essential materials that led to the dawn of life on Earth, and further study of the lunar rocks could reveal the specific deposits that made a difference back home. In this way, scientists can hopefully reconstruct a record of the Earth that was 3.8 billion years ago and better understand what made the biggest difference in the dawn of life.