On a vacuum-cleaning missionNASA/Goddard/University of ArizonaBy Matthew FrancisBennu or bust. On 8 September, the OSIRIS-REx probe will leave Earth for the asteroid Bennu, and will return with souvenirs: up to 2 kilograms of material from its surface. OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer)...