Krypton isotopes and noble gas abundances in the coma of comet 67P/Churyumov-Gerasimenko

The Rosetta Orbiter Spectrometer for Ion and Neutral Analy
sis mass spectrometer Double Focusing Mass Spectrometer
on board the European Space Agency
’
s Rosetta spacecraft detected the major isotopes of the noble gases argon, kryp-
ton, and xenon in the coma of comet 67P/Churyumov-Gerasimenko. Earlier, it was found that xenon exhibits an
isotopic composition distinct from anywhere else in the solar system. However, argon isotopes, within error, were
shown to be consistent with solar isotope abundances.
This discrepancy suggested an additional exotic
component of xenon in comet 67P/Churyumov-Gerasimenko. We show that krypton also exhibits an isotopic
composition close to solar. Furthermore, we found the argon to krypton and the krypton to xenon ratios in the comet
to be lower than solar, which is a necessity to postulate an addition of exotic xenon in the comet.