Early warning systems for asteroid impacts

Christian Gritzner
EUROSPACE GmbH, Lindenstr. 6, 14467 Potsdam, Germany.
Tel. : +49-331-284-3305,
Fax: +49-331-284-3434

Asteroids and comets are small members of our solar system. Some of them have orbits that bring them close to the Earth and a collision may occur. These objects are called NEOs (Near-Earth Objects). The probability of large (>1 km) NEOs impacting the earth is relatively low but the resulting damages would be catastrophic. But even smaller NEOs may have disastrous consequences. On June, 30th 1908, a 60 meter sized stony asteroid entered the Earth’s atmosphere at Tunguska, Siberia. Due to its velocity of about 15 km/s the NEO exploded some 9 km over ground releasing an energy of 10 Megatons of TNT. The shock wave devastated an area larger than 2,200 square km, the size of a major city such as Berlin. Due to the remote location of the impact site only two men were reported killed. Such impacts are expected once every 100 to 300 years statistically but the next large impact can only be predicted if we discover the NEO in advance. This paper presents the current NEO detection efforts and discusses the possibilities to prevent future impact catastrophes.