Experts met at the Planetary Defense Conference in Washington earlier this week (March 5–8) to discuss how to protect Earth from asteroid and comet impacts. The good news, according to Simon Worden, director of the NASA-Ames Research Center, is "We know how to do it."
The bad news: "We just don't have the money."
Near-Earth objects are asteroids and comets whose orbits cross Earth's and could therefore collide with us at some point. Earth has been hit before; it's just a matter of time before we get hit again. Various U.S. surveys have now found an estimated 70 percent of all NEOs 3,300 feet (1 kilometer) or larger, as ordered by Congress.
But objects only a few hundred feet across could take out entire states or trigger devastating tsunamis. So Congress wants scientists to find 90 percent of NEOs 460 feet (140m) across by 2020. It's doable but could cost hundreds of millions of dollars — money the White House has not requested for the NASA budget so far.
So, for the time being, the decision is to do nothing. We will follow and report on this story as it develops.