Enlarge / Artist’s conception of NASA’s OSIRIS-REx spacecraft collecting a sample from the asteroid Bennu. (credit: NASA/Goddard/University of Arizona) Hundreds of scientists and engineers have labored for the better part of two decades to reach this point. Now, their passenger-van-sized spacecraft is finally ready for its big moment, hovering near an asteroid about as long as the Empire State Building is tall. Later today, this space drama will play out 333 million kilometers from Earth.