OSIRIS-REx is NASA's first mission to an asteroid to retrieve a sample and return it to Earth. 'X' marks the spot as NASA prepares for a historic asteroid mission. NASA has selected the site on asteroid Bennu where its OSIRIS-REx spacecraft will retrieve a sample of space rock. Scientists identified four potential sites before picking a spot dubbed "Nightingale" that is located in Bennu's northern hemisphere. ASTEROID BENNU IS SHOOTING OUT ROCKS – AND NASA ISN'T SURE WHY "After thoroughly evaluating all four candidate sites, we made our final decision based on which site has the greatest amount of fine-grained material and how easily the spacecraft can access that material while keeping the spacecraft safe," said Dante Lauretta, OSIRIS-REx principal investigator at the University of Arizona in Tucson, in a statement.