Monte Carlo simulations of the water vapor plumes on Enceladus

Monte Carlo simulations are used to model the July 14, 2005 UVIS stellar occultation observations of the water vapor plumes on Enceladus. These simulations indicate that the observations can be best fit if the water molecules ejected along the Tiger Stripes in the South Polar region of Enceladus have a vertical surface velocity of 300–500 m/s at the surface. The high surface velocity suggests that the plumes on Enceladus originate from some depth beneath the surface. The total escape rate of water molecules is 4–6×1027 s−14–6×1027 s−1, or 120–180 kg/s, consistent with previous works, and more than 100 times the estimated mass escape rate for ice particles. The average deposition rate in the South Polar region is on the order of 1011 cm−2 s−1, yielding a resurfacing rate as high as 3×10−4 cm/yr3×10−4 cm/yr. The globally averaged deposition rate of water molecules is about one order of magnitude lower.