June 13, 2017

Rosetta mission science results A fifth of Earth’s atmosphere is likely from comets

Thanks to the Rosetta space mission to 67P/Churyumov–Gerasimenko, which sought to gain new insights into how our solar system formed by analysing the comet and its behaviour as it approached the Sun, scientists have now determined that a fifth of Earth’s atmosphere likely comes from comets.

For the first time, scientists have established a quantitative and qualitative link between comets and 20% of our planet’s atmosphere. Professor Bernard Marty at the CRPG Earth and planetary sciences laboratory—at the University of Lorraine, attached to the French scientific research centre CNRS—and his colleagues in the ROSINA consortium have shown through research funded by CNES that xenon isotope ratios in comet 67P have a specific signature making it possible to trace back the xenon in our atmosphere to comets.

Xenon is a rare gas whose isotopes have been produced at the end of the lives of different types of stars. In each case, xenon inherits a specific ‘fingerprint’ comprising more or less neutrons, but without changing its chemical properties, thus making it possible to trace its origin.

Analyses by the ROSINA instrument on 67P/Churyumov-Gerasimenko show that the comet’s xenon has fewer heavy isotopes than the xenon in our primordial solar system. This type of xenon, with more light isotopes than heavy ones, is also present in Earth’s atmosphere, thus suggesting a link between comets and our atmosphere. This means 20% of our atmosphere likely originates from comets.

This new discovery by Bernard Marty and his colleagues offers new and tantalizing clues to the origin of our atmosphere and encouragement to the space sector to continue its quest to solve the mysteries of our Universe.

Fabienne Lissak Head of Media             Tél. +33(0)1 44 76 78 37    fabienne.lissak@cnes.fr
Pascale Bresson Attaché de presse    Tél. +33(0)1 44 76 75 39    pascale.bresson@cnes.fr
Raphaël Sart Attaché de presse           Tél. +33(0)1 44 76 74 51    raphael.sart@cnes.fr