Irradiated interplanetary dust particles as a possible solution for the deuterium/hydrogen paradox of Earth's oceans

Determining the source of Earth's oceans is a longstanding problem in plane tary science. Possible sources of water include water ice or water of hydra tion of silicate minerals in the original material from which the bulk Eart h accreted and water brought in by late-arriving planetesimals during the h eavy bombardment period (4.5-3.8 Gyr ago) [Chyba, 1989, 1991]. Comets are a n attractive source of water because their origin in the outer solar system is consistent with the long timescale for heavy bombardment. However, the high deuterium/hydrogen (D/H) ratio of the three comets that have been stud ied, Halley, Hyakutake, and Hale-Bopp, indicates that Earth must have had a source with a low-D/H ratio as well. Here we suggest that solar wind-impla nted hydrogen on interplanetary dust particles (IDPs) provided the necessar y low-D/H component of Earth's water inventory.