Asteroid Cratering

Kurzfassung

The recent results from the Galileo Mission of the flybys of Gaspra and Ida show cratered objects. From these data, production size-frequency distributions for the impact record can be determined and compared with the record of the terrestrial planets and the earth's moon. It becomes evident that there exist striking similarities between the size-frequency distribution characteristics on the asteroids and on the inner solar system planets. This gives much support to the view that one and the same family of objects is responsible for cratering the inner solar system bodies and that these impactors are largely derived from the asteroid belt. Impact probabilities by asteroidal bodies can be assessed for the earth and will be discussed as a function of size and time. The current hazard e.g. for projectiles capable of forming 1-km craters on the earth (if the atmosphere were absent) is one crater every 6000 years for the whole surface of the earth.