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Updated: Jun 7, 2025
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Scattering And Absorption of Light in Planetary Regoliths
Published on: July 1, 2019
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A nearly terrestrial D/H for comet 67P/Churyumov-Gerasimenko
Kathleen E Mandt1, Jacob Lustig-Yaeger2, Adrienn Luspay-Kuti2
1NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA.
Science Advances
|November 13, 2024
Summary
Dust in cometary comae significantly impacts water isotope ratios. Reanalysis reveals comets may have delivered Earth-like water, challenging previous high D/H findings.
Area of Science:
- Cosmochemistry
- Planetary Science
- Astrobiology
Background:
- Cometary comae are complex mixtures of gas and dust.
- Surface and coma processing alter ice composition on dust grains.
- Sublimation of ices changes local coma composition.
Purpose of the Study:
- To re-evaluate water isotope ratios (D/H) in comet 67P/Churyumov-Gerasimenko's coma.
- To investigate the influence of dust on measured D/H values.
- To assess the implications for cometary water delivery to Earth.
Main Methods:
- Analysis of over 4000 water isotope measurements from the Rosetta mission.
- Comparison of D/H ratios at varying distances from the nucleus.
- Assessment of gas-phase versus dust-influenced measurements.
Main Results:
- Dust particles significantly elevate local Deuterium/Hydrogen (D/H) ratios in the coma.
- Well-mixed gas far from the nucleus shows a D/H ratio similar to Earth.
- This revised D/H value aligns with other Jupiter family comets.
Conclusions:
- Previous high D/H measurements in comet 67P were likely influenced by dust.
- Comets may have delivered water with a terrestrial D/H ratio to early Earth.
- This finding impacts models of solar system formation and water origin on Earth.
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