NASA set to chase down asteroid Bennu, grab some gravel to bring home

CAPE CANAVERAL, FLORIDA – NASA is going after an asteroid this week like never before. It's launching a spacecraft to the exotic black rock named Bennu, vacuuming up handfuls of gravel from the surface, and then in a grand finale, delivering the pay dirt all the way back to Earth. The mission will take seven years, from Thursday night's planned liftoff from Cape Canaveral to the return of the asteroid samples in 2023, and cover an incredible 4 billion miles (6½ billion km) through space. It promises to be the biggest cosmic bounty since the Apollo moon rocks, hand-picked and delivered by astronauts in the late 1960s and early 1970s. NASA has already brought back comet dust and specks of solar wind.