From Scientific American:
As detailed in this video, Bennu is a carbonaceous asteroid, an ancient relic from the solar system’s infancy that is filled with organic molecules. Other asteroids like Bennu may have seeded the early, prebiotic Earth with this material, contributing to the primordial soup from which life eventually emerged. By studying the sizable and pristine sample of material OSIRIS-REx is expected to bring back to Earth from Bennu, scientists hope to unlock deep secrets about the origins of the terrestrial planets and of life itself.
Morever, because Bennu has a slight-but-significant chance of striking our planet late in the 22nd century, it is also one of the most threatening asteroids known to humanity. Its orbit is evolving, pushed by the subtle influence of sunlight so that its exact future trajectory difficult to predict. As part of its preparation for gathering a sample, OSIRIS-REx will create detailed maps of Bennu’s surface and characterize its slowly evolving orbit with unprecedented precision, allowing researchers to better forecast its future movements and plan ways to deflect it away from Earth. The experience gained from OSIRIS-REx’s operations at Bennu could also pave the way for future efforts to mine valuable resource from asteroids.
After launching in September 2016, OSIRIS-REx will arrive at Bennu in August 2018, and will spend roughly two years at the asteroid before gathering its sample. At Bennu, decades of effort and investment will culminate in a five-second “touch and go” maneuver in which OSIRIS-REx autonomously descends to a collection site and quickly gathers a sample before rocketing back into orbit. After a 2.5-year journey back to Earth, the spacecraft will jettison its precious cargo in a reentry capsule that will drift down to Earth on parachutes in late …