#rosetta spacecraft

presenting magical girl rosetta

colored version

Greyscale photograph of Comet Churyumov–Gerasimenko 

The enigmatic noble gas xenon has been presenting scientists with puzzling riddles for decades, including how it got to Earth, and then its apparent disappearance since arriving.

But geochemists may have finally figured out where at least some of the xenon in Earth's atmosphere might have originated - and it's not from here.

New results from the Rosetta spacecraft reveal that almost a quarter of the xenon found in our atmosphere may have come from comets.

In addition to solving the long-held mystery about the origins of the rare gas, the new findings could help scientists understand how comets have potentially delivered other materials, such as water, to our planet.

"The xenon isotopic composition matches that of a primordial atmospheric component," says Bernard Marty, lead author and geochemist at the University of Lorraine, France. "The present-day Earth atmosphere contains 22 percent cometary xenon."