SOURCE; http://www.nytimes.com/2016/11/15/science/nasa-and-fema-rehearse-for-the-unthinkable-an-asteroid-strike-on-los-angeles.html
 

Imagine if scientists discovered that an asteroid was hurtling toward Los Angeles.

The possibility has existed on the pages of Hollywood scripts. But in what may be a case of life imitating art, NASA, the Federal Emergency Management Agency and other government agencies engaged last month in a planetary protection exercise to consider the potentially devastating consequences of a 330-foot asteroid hitting the Earth.

The possibility has existed on the pages of Hollywood scripts. But in what may be a case of life imitating art, NASA, the Federal Emergency Management Agency and other government agencies engaged last month in a planetary protection exercise to consider the potentially devastating consequences of a 330-foot asteroid hitting the Earth.

The simulation projected a worst-case blast wave by an asteroid strike in 2020 that could level structures across 30 miles, require a mass evacuation of the Los Angeles area and cause tens of thousands of casualties.

In 1998, the movie “Armageddon” dramatized an even greater fictional threat. In that blockbuster, a ragtag crew was sent on a mission to drill into an asteroid and set off a nuclear bomb to avert a global catastrophe. As the character Harry Stamper, portrayed by Bruce Willis, summed up to his crewmates: “The United States government just asked us to save the world.”

Don’t expect the need for such Hollywood heroics in real life, however. An asteroid that could cause such damage has no significant chance of striking Earth within the next century, Paul Chodas, manager of NASA’s Center for Near-Earth Object Studies at the Jet Propulsion Laboratory in Pasadena, Calif., said in an email.

The center relies on several telescopes, such as the Catalina Sky Survey at the University of Arizona, to track potentially hazardous asteroids and comets. These objects, which are leftover matter from the formation of planets, can come dangerously close to Earth or cross its trajectory.

The center lists 659 asteroids that have some probability of striking the planet, “but none pose a significant threat over the next century, either because the probabilities are extraordinarily small, or the asteroids themselves are extremely small,” Mr. Chodas said.

“Nevertheless, we must continue searching for asteroids in case there is one that is heading our way,” he added.