DISCOVERY AND FOLLOW-UP SIMULATIONS FOR SMALL EARTH-CROSSING ASTEROIDS

Discovery and follow-up strategies are simulated for a model populatio n of Earth-crossing aster;; olds (ECAs), in line with the 1908 Tungusk a explosion being used by a stony asteroidal body. ECAs with minimum d iameters varying from 10m to 1 km are concentrated on, and attention i s paid to the discovery completeness as a function of the semimajor ax is, eccentricity, and inclination to understand the discovery biases i n the proposed Spaceguard Survey for near-Earth objects. It is noted t hat the so-called standard survey strategy does not favor the discover y of large ECAs with small orbital intersection distances om the Earth 's orbit. Orbital covariances and quality metrics are introduced to si mulate the follow-up prospects for ECAs discovered at different locati ons on the sky plane. The quality metrics confirm an intuitively clear east-west asymmetry: ECAs discovered in the east are easier to follow up than those discovered in the west. For ECAs larger than 1 km, oppo sition searches field the best orbits, whereas for small ECAs, the opt imum search window shifts to the east. (C) 1998 Elsevier Science Ltd. All rights reserved.