After a seven-year quest, NASA's OSIRIS-REx mission expected to deliver Bennu asteroid samples to Earth

Open this photo in gallery: An artist rendering depicts the Origins Spectral Interpretation Resource Identification Security – Regolith Explorer (OSIRIS-REx) spacecraft contacting the asteroid Bennu. The spacecraft will fly by Earth on Sept. 24, and drop off what is expected to be at least a cupful of rubble it grabbed from the asteroid.The Associated Press Like a celestial courier on an express run, NASA's OSIRIS-REx spacecraft is speeding toward Earth and is less than 48 hours from delivering a precious cargo of extraterrestrial material. Stowed on board is a cache of gravel and dust from the asteroid Bennu. The spacecraft…