Herschel observations of comet 103P/Hartley 2: D/H in a Jupiter family comet
Abstract
Water is a key ingredient for the development of life. For decades, the source of Earth volatiles, especially water, has been a subject of debate. Proposed explanations include accretion of material in the vicinity of the Earth orbit or delivery by impacts of asteroids or comets during the late heavy bombardment (LHB). The source of water reservoirs can be accurately traced by measurements of the deuterium-to-hydrogen isotopic ratio (D/H). Previous measurements of this ratio in several Oort cloud comets resulted in a value twice as high as that in the Earth oceans, leading to the generally accepted conclusion that comets are unlikely to be the primary source of ocean water. Together with orbital modelling, these measurements suggested instead that asteroids with composition similar to that of C1 meteoroids were the main water source. Using the Herschel Space Observatory, we have obtained the first measurement of the D/H ratio in a Jupiter-Family comet. We discuss the implications of these observations for the origin of ocean water.
- Publication:
-
The Molecular Universe
- Pub Date:
- May 2011
- Bibcode:
- 2011IAUS..280E..15L