In 2016, NASA launched a spacecraft to do something rarely attempted before: Collect space rocks from a potentially dangerous asteroid. The mission, named OSIRIS-REx, was successful. Tuesday, scientists opened a sealed canister containing the samples from the asteroid Bennu. Science correspondent Nell Greenfieledboyce talks to host Regina G. Barber about the mission's close calls and what NASA might learn from these space rocks that are older than our planet. Listen to Short Wave on Spotify, Apple Podcasts and Google Podcasts.Have a space mystery? Send us your questions to shortwave@npr.org.