Discovery and follow-up simulations for small Earth-crossing asteroids

Discovery and follow-up strategies are simulated for a model population of Earth-crossing asteroids (ECAs), in line with the 1908 Tunguska explosion being caused by a stony asteroidal body. ECAs with minimum diameters varying from 10m to 1 km are concentrated on, and attention is paid to the discovery completeness as a function of the semimajor axis, eccentricity, and inclination to understand the discovery biases in the proposed Spaceguard Survey for near-Earth objects. It is noted that the so-called standard survey strategy does not favor the discovery of large ECAs with small orbital intersection distances from the Earthʹs orbit. Orbital covariances and quality metrics are introduced to simulate the follow-up prospects for ECAs discovered at different locations 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, opposition searches yield the best orbits, whereas for small ECAs, the optimum search window shifts to the east.