Comets anyone?


A new study by researchers at Tel Aviv University in Israel has suggested that comets might have provided the elements for the emergence of life on our planet.
While investigating the chemical make-up of comets, Professor Akiva Bar-Nun of the Department of Geophysics and Planetary Sciences at Tel Aviv University found they were the source of missing ingredients needed for life in Earth's ancient primordial soup.

"When comets slammed into the Earth through the atmosphere about four billion years ago, they delivered a payload of organic materials to the young Earth, adding materials that combined with Earth's own large reservoir of organics and led to the emergence of life," said Professor Bar-Nun.

It was the chemical composition of comets that allowed them to kickstart life, he added.

Using a one-of-a-kind machine built at Tel Aviv University, researchers were able to simulate comet ice, and found that comets contain ingredients necessary for providing the basic nutrients of life.

Specifically, Prof. Bar-Nun looked at the noble gases Argon, Krypton and Xenon, because they do not interact with any other elements and are not destroyed by Earth's oxygen.

These elements have maintained stable proportions in the Earth's atmosphere throughout the lifetime of the planet, he explained.

"Now, if we look at these elements in the atmosphere of the Earth and in meteorites, we see that neither is identical to the ratio in the sun's composition. Moreover, the ratios in the atmosphere are vastly different than the ratios in meteorites which make up the bulk of the Earth," said Bar-Nun.

"So we need another source of noble gases which, when added to these meteorites or asteroid influx, could change the ratio. And this came from comets," he added.

During the comets' formation, the porous ice trapped gases and organic chemicals that were present in outer space.

"The pattern of trapping of noble gases in the ice gives a certain ratio of Argon to Krypton to Xenon, and this ratio - together with the ratio of gases that come from rocky bodies - gives us the ratio that we observe in the atmosphere of the Earth," said Bar-Nun.

Thus, the arrival on Earth of comets and asteroids led to the necessary ratio of materials for organic life, "which eventually were dissolved in the ocean and started the long process leading to the emergence of life on Earth," he added.