Comets Brought Water To Earth Billions Of Years Ago, New Study Claims

Comets may have been responsible for the presence of water on Earth, scientists have claimed, according to a new research published this week in Science Advances. The researchers focused on Comet 67P/Churyumov-Gerasimenko and discovered that the molecular structure of water found on the celestial body closely resembled that of Earth's oceans. While water existed in the gas and dust form when Earth formed around 4.6 billion years ago, questions regarding how it ultimately became rich in liquid water have puzzled scientists.

Researchers are of the view that a substantial portion of our oceans came from the ice and minerals on asteroids and possibly comets that crashed into Earth. To further their theory, the researchers led by Kathleen Mandt, a planetary scientist at NASA's Goddard Space Flight Center, decided to use an advanced statistical computation technique to find the molecular structure of water on 67P which belongs to the Jupiter family of comets, using data captured by European Space Agency's (ESA) Rosetta mission to the asteroid.

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Earth's specific signature

The water on Earth has a unique molecular signature which has to do with specific rations of the hydrogen variant, or isotope, called deuterium. For the last few decades, deuterium levels in water found in the vapour trails of several Jupiter-family comets displayed similar levels to that of Earth's water.

"So I was just curious if we could find evidence for that happening at 67P. And this is just one of those very rare cases where you propose a hypothesis and actually find it happening," said Ms Mandt.

As it turned out, Ms Mandt's team found a clear connection between deuterium measurements in the comet and the amount of dust around the Rosetta spacecraft.

"As a comet moves in its orbit closer to the Sun, its surface warms up, causing gas to release from the surface, including dust with bits of water ice on it. Water with deuterium sticks to dust grains more readily than regular water does," the study highlighted.

"When the ice on these dust grains is released into the coma, this effect could make the comet appear to have more deuterium than it has," it added.

The research has big implications not only for understanding comets' role in delivering Earth's water but also for understanding comet observations that provide insight into the formation of the early solar system.