NASA'S asteroid sample return mission OSIRIS-REx marked a milestone this month. The unmanned spacecraft is still a long way from its target, the asteroid Bennu, but the mission began "proximity operations" and captured the first images of the asteroid. The team leading the mission is based at the University of Arizona, and shared some of those photos this week. OSIRIS-REx launched in September 2016 and is expected to arrive at Bennu in December. Samples collected from the surface will be delivered back to Earth in September 2023.