A spacecraft destined to bring samples of an asteroid back to Earth is scheduled to launch tonight. NASA’s OSIRIS-REx mission will launch September 8 at 7:05 p.m. EDT atop an Atlas V rocket from Cape Canaveral Air Force station in Florida. The probe will head for 101955 Bennu, a roughly 500-meter-wide asteroid whose 1.2-year orbit intersects that of Earth. Once the spacecraft arrives in late 2018, it will spend more than a year mapping the asteroid before reaching out and grabbing a sample in July 2020.
By bringing an asteroid sample to Earth, planetary scientists hope to learn more about the early solar system, what resources are available for future space explorers and how to knock off course any asteroids that pose a risk to Earth. Bennu itself has about a 1 in 2,700 chance of striking Earth late in the 22nd century.
To get a piece of Bennu, OSIRIS-REx will descend toward the surface and extend a robotic arm that will contact the surface for about 5 seconds. A puff of nitrogen gas will stir up rocks and soil, some of which will be collected in a container. The sample will be placed in a capsule for the ride home.
OSIRIS-REx will leave Bennu no earlier than March 2021. As it passes Earth in September 2023, the spacecraft will jettison its cargo, dropping the capsule in the Utah desert.