Did Comets Kick-Start Life On Earth?

An artist concept of a young rocky planet being bombarded by comets. Credit: NASA/JPL-Caltech

A thought-provoking new study is bolstering the notion that comets raining down on Earth billions of years ago may have seeded our young planet with the organic building blocks of life.

Through powerful computer simulations of comet impacts of various sizes, astronomers have found that it is possible that complex organic molecules  may have hitched a ride on inbound comets, successfully delivering them to the surface of the Earth. (Related: Did Comets Make Life on Earth Possible?)

Previous research suggests that our planet billions of years ago was without much of a habitable environment except possibly for the ancient oceans where all the ingredients of life may have come together. (See also: Comet Swarm Delivered Earth’s Oceans?)

This new study however suggests that comets might have been key in bringing to Earth the right molecules, like copious amounts of water, carbon dioxide, ammonia and alcohol too.

Researchers estimate that when the Earth was young and was going through periods of ongoing bombardments from comets and asteroids, there may have been as much as 10 trillion kilograms (22 trillion pounds) of organic matter carried to Earth’ surface each and every year!

These impacts would end up,  “delivering up to several orders of magnitude greater mass of organics than what likely pre-existed on the planet,” said co-author Nir Goldman of Lawrence Livermore National Laboratory, California, in a press statement.

The energy of the impact itself would be nature’s driving force that helped spark the synthesis of a soup of prebiotic compounds that would eventually help form  important precursors that would jump-start life- like proteins, enzymes, sugars and even the bases of DNA and RNA.

“Cometary impacts could result in the synthesis of prebiotic molecules without the need for other ‘special’ conditions, such as the presence of catalysts, UV radiation, or special pre-existing conditions on a planet,” said Goldman.

“This data is critical in understanding the role of impact events in the formation of life-building compounds both on early Earth and on other planets and in guiding future experimentation in these areas.”

The research will appear in the June 20 issue of The Journal of Physical Chemistry A.

Changing Planet

Meet the Author
Andrew Fazekas, aka The Night Sky Guy, is a science writer, broadcaster, and lecturer who loves to share his passion for the wonders of the universe through all media. He is a regular contributor to National Geographic News and is the national cosmic correspondent for Canada’s Weather Network TV channel, space columnist for CBC Radio network, and a consultant for the Canadian Space Agency. As a member of the Royal Astronomical Society of Canada, Andrew has been observing the heavens from Montreal for over a quarter century and has never met a clear night sky he didn’t like.