  (1) Ceres, the largest reservoir of water in the main-belt, was recently
visited by the Dawn spacecraft that revealed several areas bearing H$_2$O-ice
features. Independent telescopic observations showed a water exosphere of
currently unknown origin. We explore the effects of meteoroid impacts on Ceres
considering the topography obtained from the Dawn mission using a widely-used
micro-meteoroid model and ray-tracing techniques. Meteoroid populations with
$0.01-2$ mm diameters are considered. We analyze the short-term effects Ceres
experiences during its current orbit as well as long-term effects over the
entire precession cycle. We find the entire surface is subject to meteoroid
bombardment leaving no areas in permanent shadow with respect to meteoroid
influx. The equatorial parts of Ceres produce $80\%$ more ejecta than the polar
regions due to the large impact velocity of long-period comets. Mass flux,
energy flux, and ejecta production vary seasonally by a factor of $3-7$ due to
the inclined eccentric orbit. Compared to Mercury and the Moon, Ceres
experiences significantly smaller effects of micro-meteoroid bombardment, with
a total mass flux of $4.5\pm1.2\times10^{-17}$ kg m$^{-2}$ s$^{-1}$. On average
Mercury is subjected to a $50\times$ larger mass flux and generates $700\times$
more ejecta than Ceres, while the lunar mass flux is $10\times$ larger, and the
ejecta generation is $30\times$ larger than on Ceres. For these reasons, we
find that meteoroid impacts are an unlikely candidate for the production of a
water exosphere or significant excavation of surface features. The surface
turnover rate from the micro-meteoroid populations considered is estimated to
be $1.25$ Myr on Ceres.

Earth and Planetary Astrophysics