A Comprehensive Model of the Meteoroid Environment around Mercury

To characterize the meteoroid environment around Mercury and its contribution to the planet's exosphere, we combined four distinctive sources of meteoroids in the solar system: main-belt asteroids, Jupiter-family comets, Halley-type comets, and Oort Cloud comets. All meteoroid populations are described by currently available dynamical models. We used a recent calibration of the meteoroid influx onto Earth as a constraint for the combined population model on Mercury. We predict vastly different distributions of orbital elements, impact velocities, and directions of arrival for all four meteoroid populations at Mercury. We demonstrate that the most likely model of Mercury's meteoroid environment-in the sense of agreement with Earth-provides good agreement with previously reported observations of Mercurys exosphere by the MESSENGER spacecraft and is not highly sensitive to variations of uncertain parameters such as the ratio of these populations at Earth, the size-frequency distribution, and the collisional lifetime of meteoroids. Finally, we provide a fully calibrated model consisting of high-resolution maps of mass influx and surface vaporization rates for different values of Mercury's true anomaly angle.