The RQ36 is an asteroid about 500 yards across, and it has a 1 in 2,400 chance to hit the earth late in the 22nd century. In 2016, NASA will do what it does best and send a probe to study it.
The organization's Near-Earth Object (NEO) observations program attempts to find the largest objects in the solar system, and then tries to predict the possibility of a collision with our planet. Accurately modeling a NEO's path is difficult, because numerous forces are acting on it all at once, many of them small and hard to to predict. For example, every time the asteroid swings near the earth, its trajectory is very slightly altered by the planet's gravity.
OSIRIS-REx will primarily focus on studying the Yarkovsky effect, which is when an object absorbs heat, then radiates it in another direction, subtly changing its path. This effect is why some scientists think spray-painting an asteroid could be a feasible solution for diverting it away from the earth.
Jason Dworkin, OSIRIS-REx project scientist at NASA's Goddard space flight center, told ScienceDaily that this project could allow scientists to estimate the Yarkovsky effect with at least twice the precision they can now.
When asked what could be done if an asteroid were accurately predicted to be on a collision course with the earth, Edward Beshore, deputy principal investigator for the OSIRIS-REx asteroid sample return mission at the University of Arizona, said that there are several strategies to mitigate the damage. "We could explode a small nuclear device close above the surface on one side of the asteroid," he told ScienceDaily. "This could be very effective -- it would vaporize the surface layer, which would then fly off at very high speed, causing a rocket thrust that would shove everything over by a few centimeters per second. This might be plenty to deflect the asteroid.
"Other strategies include kinetic impactors, where you strike an asteroid very hard with a heavy projectile moving at high speed. In 2005, NASA's Deep Impact mission hit comet Tempel 1 with a 370-kilogram (over 815-pound) copper slug at about five kilometers per second (over 11,000 miles per hour), not nearly enough to significantly alter the orbit of the five-kilometer-sized body, but a proof of the technology for this kind of mission. Another idea is to use a gravity tractor -- station a spacecraft precisely enough near the asteroid which would gradually deflect it with only its gravitational pull."
The most essential part of these strategies is discovering the NEO with enough time to deflect it-- Beshore likened it to deflecting an arrow as it leaves the string rather than waiting for it to reach the target, at which point it would take far more force to deflect.
