The possibility of the Earth being struck by comets or asteroids will be discussed by Paul Chodas of NASA's Jet Propulsion Laboratory (JPL) when he moderates one of the daily press conferences at the seventh International Asteroids, Comets and Meteors Conference (ACM) at Cornell July 26-30.
The conference is sponsored by NASA, the Applied Physics Laboratory of Johns Hopkins University, JPL and Cornell. It is expected to attract more than 500 scientists and other visitors from around the world.
Chodas' press conference Tuesday, July 27, at 10 a.m. in 305 Ives Hall will cover asteroids and meteors collectively known as near-Earth objects (NEOs). Other participants will include David Rabinowitz of JPL, Richard Binzel of the Massachusetts Institute of Technology, Alan Harris of JPL and Andrea Milani of the University of Pisa, Italy.
In recent movies, asteroids and comets are shown threatening to collide with the Earth, only to be destroyed at the last minute by astronaut heroics. But Chodas believes that the hazards of collisions with comets or asteroids are more than a topic for fiction. Chodas and Milani will discuss their independent efforts to predict close-Earth approaches and impact probabilities further into the future than has been previously possible.
It has been estimated that only 15 to 20 percent of NEOs larger than one kilometer have been detected to date.
A new analysis by Rabinowitz shows that there may be only half as many large hazardous objects as previously estimated. Harris will present new evidence to refute a controversial theory that the Earth is continually bombarded by a population of house-sized comets.
What is the nature of these seemingly "loose cannons" that might be posing a threat? A new view has evolved, suggesting that many large asteroids are "rubble-piles," according to William Bottke, a research associate in Cornell's Department of Astronomy, who will moderate the press session on asteroid moons and spins on Friday, July 30, at 10 a.m. in the Princeton-Yale Room of Statler Hotel.
In another of the conference's daily press conferences, Steven Ostro of JPL will discuss dramatic new close-up radar images of asteroids obtained by the Arecibo 305-meter radio/radar telescope in Puerto Rico. The Arecibo Observatory is operated by Cornell for the National Science Foundation. Ostro also will report on an asteroid, the size of a baseball diamond, that is the smallest solar system object ever studied in detail.
On Monday, July 26, at 10 a.m. in 305 Ives Hall, Ostro will describe how radar is being used to construct geologically detailed three-dimensional models of distant bodies, including 37 main-belt asteroids and 50 near-Earth asteroids.
High-resolution imaging has been obtained for a number of NEOs, with the most impressive results being obtained for asteroids 1998 KY26 and Toutatis, which Ostro will discuss, and asteroid 1992 SK.
Ostro and Donald Campbell, professor of astronomy at Cornell, also will describe plans for the use of the Very Long Baseline Array (VLBA), in conjunction with Arecibo Observatory and JPL/Goldstone radars, to image near-Earth asteroids and comets.
A full schedule of the ACM press conferences is available on the ACM media web site at http://www.news.cornell.edu/releases/July99/ACM/. The conference web site is at http://scorpio.tn.cornell.edu/ACM/.
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