OSIRIS-REx Arrives at Asteroid Bennu • Taking the measure of an asteroid By Daniel Strain • Dec. 3, 2018 CU Boulder scientists have a front row seat today to observe a NASA spacecraft as it arrives at the asteroid Bennu, coming to within 4.5 miles of the space rock. This close approach, followed by a flyby Dec. 4, up is the first in a series of planned meet ups between the Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer (OSIRIS-REx) and Bennu. Today's encoun