The European Space Agency’s Rosetta comet mission (with Philae comet lander) produced a wealth of valuable information about comets and the formation of the solar system. One interesting piece of information that has just been released this week by the scientific team analyzing the data is that the water on the comet where Philae landed and sampled has a different origin than the water on Earth.

Rosetta Reveals Water On Earth Likely Not From Comets

Mystery of water on Earth

A big mystery about the Earth’s formation is that it was so hot when the planet formed 4.6 billion years ago that all water should have boiled off. This begs the question of where all the water on the planet today came from. Many scientists believe that the water was brought to the planet by comets and asteroids colliding with the surface billions of years ago.

This latest finding from the ESA’s Rosetta mission throws doubt on this theory. When it arrived at Comet 67P/Churyumov-Gerasimenko, Rosetta began a series of measurements. In specific, it determined the proportion of deuterium, which is a form of hydrogen with an additional neutron-to normal hydrogen, in the water on the comet. This proportion of deuterium makes it possible to know exactly where the water came from since the proportion should change based on distance from the sun.

Statements from Rosetta researchers

“This surprising finding could indicate a diverse origin for the Jupiter-family comets – perhaps they formed over a wider range of distances in the young Solar System than we previously thought,” noted Kathrin Altwegg, principal investigator for ROSINA and lead author of the paper published in Science this week.

Altwegg added, “Our finding also rules out the idea that Jupiter-family comets contain solely Earth ocean-like water, and adds weight to models that place more emphasis on asteroids as the main delivery mechanism for Earth’s oceans.”

“We knew that Rosetta’s in situ analysis of this comet was always going to throw up surprises for the bigger picture of Solar System science, and this outstanding observation certainly adds fuel to the debate about the origin of Earth’s water,” commented Matt Taylor, ESA’s Rosetta project scientist.

“As Rosetta continues to follow the comet on its orbit around the Sun throughout next year, we’ll be keeping a close watch on how it evolves and behaves, which will give us unique insight into the mysterious world of comets and their contribution to our understanding of the evolution of the Solar System,” he continued.