Watch Live: NASA OSIRIS-REx Arrives at Asteroid Bennu

Two years and two months after it launched from Cape Canaveral Air Force Station, NASA's $800-million mission to the asteroid belt between Mars and Jupiter will reach a pivotal moment Monday, when the agency's OSIRIS-REx spacecraft is slated to rendezvous with its scientific target: a dark, round, carbon-rich asteroid named Bennu. At fewer than 500 meters in diameter, Bennu is a small solar-system body with big scientific potential: Astronomers suspect the asteroid's rocky composition has remained more or less unchanged since it formed some 4.5 billion years ago. Collecting and analyzing a sample of the asteroid could tell scientists a lot about the origins of our solar system, its planets, and the source of organic molecules that may have given rise to life on Earth. But before anyone can sift through a sample from Bennu, NASA must first collect and retrieve it. Doing so will require several major steps, the first of which is slated to kick off Monday, at around 9:00 am PT, when OSIRIS-REx (short for Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer) will arrive at Bennu and begin its months-long process of surveying the asteroid's surface.