Dr. Paul Chodas is manager of the Center for Near-Earth Object Studies (CNEOS) at the Jet Propulsion Laboratory (JPL) in California. CNEOS is NASA’s center for computing high precision orbits of near-Earth asteroids and comets using tracking observations from observatories around the world. The team at CNEOS uses these orbits to determine whether any of these 17,000 objects has a significant chance of impacting Earth over the next hundred years. Dr. Chodas has worked on orbit modeling at JPL since the 1980s and in the 1990s was responsible for computing the times and locations of the impacts of comet Shoemaker-Levy 9 on Jupiter. More recently, he and his team accurately predicted the impact of the tiny asteroid 2008 TC3 in Oct. 2008. Dr. Chodas has developed several hypothetical impact scenarios used by the community as exercises to understand how we might deal with a threatening asteroid.