Abstract

The recent remarkable visit of the European Space Agency’s mission to the comet 67P/Chuyumov-Gerasimenko(hereafter 67P/C-G) by the Rosetta spacecraft see Altwegg et al. (2014) returned new important data regardingthe origin of the water on Earth. The experimental data showed very clearly that the water found in the comethad a quite different ratio of d (deuterium) to h (hydrogen), considerably larger (by about 3.6 times) than the waterfound here on Earth. This result would appear to contradict the argument that comets delivered water duringEarth’s early era of formation. There have been a number of measurements and arguments put forth by planetaryscientists about this issue (see the discussion and references in Altwegg et al. (2014). The d/h data from the Rosettamission, therefore, seems to have conclusively answered the question “did the Earth get its water from comets suchas 67P/C-G?” in the negative. That this conclusion may not be correct is the subject of this paper. Specifically, thed/h ratio may not have remained constant on Earth over its history due to a more rapid consumption of deuteriumthan of hydrogen (Note: p and h will be used interchangeably).

This work is licensed under a Creative Commons Attribution 4.0 License.