Physicist: For this mission, due to launch soon, I can not do better than quote the description on the NASA mission page and provide three links:
OSIRIS-REx will travel to a near-Earth asteroid called Bennu and bring a small sample back to Earth for study. The mission is scheduled to launch Sept. 8, 2016. As planned, the spacecraft will reach its asteroid target in 2018 and return a sample to Earth in 2023.
NASA missions OSIRIS-REx page. Lots to see here [link]
Science at NASA missions OSIRIS-REx page. Follow the two project pages [link]
Video. You can find many more via the two links above [link]
Principal investigator page [link]
Science at NASA video [link]
Another video about mapping Bennu [link]