A nearly terrestrial D/H for comet 67P/Churyumov-Gerasimenko.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39536098.
- Also identified by DOI 10.1126/sciadv.adp2191 and PMC identifier 11559612.
- Licence recorded as CC BY-NC.
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Abstract
Cometary comae are a mixture of gas and ice-covered dust. Processing on the surface and in the coma change the composition of ice on dust grains relative to that of the nucleus. As the ice on dust grains sublimates, the local coma composition changes. Rosetta observations of 67P/Churyumov-Gerasimenko previously reported one of the highest D/H values for a comet. However, reanalysis of more than 4000 water isotope measurements over the full mission shows that dust markedly increases local D/H. The isotope ratio measured at a distance from the nucleus where the gas is well mixed is close to terrestrial, like that of other Jupiter family comets. This lower D/H has implications for understanding comet formation and the role of comets in delivering water to Earth.