Dr. Weiping Yu returns for another exciting segment of Science and U. The physicist comments on the news that NASA’s OSIRIS-REX spacecraft has touched the surface of an asteroid on Tuesday to gather a sample of rocks and dirt. What can we expect from the rubble that OSIRIS-REX is bringing home? What's the difference, from a physics standpoint, between an asteroid and a comet? Plus, Dr. Yu also analysis the claim that a new “light sail” concept for spaceflight will unlock interstellar travel.