Numerical Simulation of High-Velocity Impact Ejecta Following Falls of Comets and Asteroids onto the Moon

摘要

High-velocity comet and asteroid impacts onto the Moon are considered and the material masses ejected after such impacts at velocities above the second-cosmic velocity for the Moon (2.4 km/s) are calculated. Although the results depend on a projectile type and the velocity and angle of an impact, it has been demonstrated that, on average, the lunar mass decreases with time. The Moon has lost about 5 × 10~(18) kg. that is, about one-hundredth of a percent of its mass, over the last 3.8-3.9 billion years. The ejection of lunar meteorites and lunar dust, rich in ~3He, is considered as well. The results of the study are compared to the results of earlier computations and data on lunar meteorites.