Exogeneous delivery of water to Mercury

Mueller, M., Frantseva, K., Nesvorny, D., Loes ten Kate, I. & van der Tak, F., 2018.

Research output: Contribution to conferenceAbstractAcademic

Radar and in-situ observations of the bright and dark polar deposits in permanently shadowed north-polar regions of Mercury indicate that these regions contain water ice despite the planet's proximity to the Sun. Previous studies have shown that interplanetary dust particles (IDPs), asteroids and comets are possible sources of water on Mercury. Here we study how much water and organics certain asteroids (C-type), comets and IDPs can deliver to Mercury using the most recent minor bodies catalogs. We have performed numerical gravity simulations of asteroid and comet impact rates on Mercury within the past few Myr. We use the N-body integrator RMVS/Swifter to propagate the Sun and the eight planets from their current positions. Separately, we add comets and asteroids to the simulations as massless test particles, based on their current orbital distributions. Asteroid impactors are assigned a probability of being water-rich (C-class) based on the measured distribution of taxonomic types across the Main Asteroid Belt. For comets, we assume a constant water fraction. For IDPs, we use a dynamical model to compute the dust flux on Mercury. Immediate post-impact ejection into outer space is taken into account as is water diffusion across the surface into the polar cold traps. We find that exogeneous water sources can easily deliver the amount of water required by the available radar and MESSENGER data; taken together, they require 250-670 Myr to deliver the lower limit on available water. Over the \sim 3.5 Gyr since the end of the Late Heavy Bombardment, exogenous sources delivered a maximum of 1.7-7.4 m of water ice to the polar regions of Mercury. Among exogeneous water sources, we find IDPs to dominate over asteroids and comets. Implications for the upcoming Bepi-Colombo observations are discussed.
Original languageEnglish
Publication statusPublished - 2018
EventAmerican Astronomical Society, DPS meeting #50, id.100.09 - Knoxville, Tennessee, United States
Duration: 21-Oct-201826-Oct-2018


ConferenceAmerican Astronomical Society, DPS meeting #50, id.100.09
CountryUnited States
CityKnoxville, Tennessee


American Astronomical Society, DPS meeting #50, id.100.09


Knoxville, Tennessee, United States

Event: Conference

ID: 71847779