APL Colloquium

April 8, 2005

Colloquium Topic: Defending the Earth from Asteroid Impacts

The greatest natural threat to the long-term survivability of mankind is an asteroid impact with the Earth. Throughout its history, the Earth has continuously been bombarded by objects ranging in size from dust particles to comets and asteroids greater than 10 km in diameter. An impact by an asteroid larger than a kilometer in diameter is on the threshold of a global disaster. Although the probability of the Earth being hit by a large object in this century is low, the effects of an impact are so catastrophic that it is essential to consider a defense against such an occurrence. A complete Earth protection system would start with facilities to identify and catalog all significant potential impactors. When one is identified, it is vital to learn its detailed characteristics in order to select an appropriate means of deflection. A number of schemes for moving an asteroid have been studied and some of them are feasible with today's technology. Finally, a plan for the overall coordination of these efforts would be required. With currently available technologies, about 30 years of advance warning is required for successful asteroid deflection. Therefore, we should be initiating an Earth protection system soon.

Colloquium Speaker: Robert E. Gold

Dr. Robert Gold is the Chief Technologist for the Space Department at the Applied Physics Laboratory of the Johns Hopkins University. He is a physicist who has specialized in heliospheric and planetary particles and fields research. He was principal investigator for the study of SHIELD - A Comprehensive Earth Protection System funded by of the NASA Institute for Advanced Concepts in 1999. In 2003, he was a member of the NASA Near-Earth Object Science Definition Team that examined the feasibility of extending the search for near-Earth objects to smaller limiting diameters. Dr. Gold is the Science Payload Manager for the MESSENGER mission on its way to orbit the planet Mercury. He also served in that position for the Near Earth Asteroid Rendezvous (NEAR) mission that was the first to orbit and land on an asteroid. He is the lead investigator for two instruments on the Advanced Composition Explorer (ACE) mission that examines the structure of the interplanetary medium and provides up to one hour early warning of space weather disturbances headed toward Earth. He is also the project scientist for the HI-SCALE instrument on Ulysses, which is the first mission to examine the space above the poles of the Sun. Dr. Gold received a Ph. D. from the University of Denver in 1972. He has over 75 scientific publications. Asteroid 4955 Gold was named for his work on the NEAR mission.