The Known and Unknown of Asteroid Bennu
Our knowledge of smaller bodies in the Solar System, from dwarf planets to comets, has expanded rapidly in recent years thanks to missions like Dawn and Rosetta. Coming soon is NASA’s OSIRIS-REx mission, which will study and return a sample from the asteroid Bennu.
NASA has released a new animation that explains what scientists currently know about Bennu, and what mysteries the asteroid still holds:
Asteroid Bennu’s Journey. Credit: NASA Goddard (YouTube)
Bennu was selected as the target for OSIRIS-REx due to its proximity to the Earth, its size and its composition.
Bennu is a Near-Earth Object (NEO), a class of object that rates high on the list of potential impact hazards for our planet. Impact events may have delivered molecules important for the origin of life on Earth. However, impacts are also thought to be responsible for some of the largest mass extinctions in history, and have shaped the evolution of Earth’s biosphere. Future impacts could have a profound effect on the habitability of our planet.
Bennu is large enough to make it safe for OSIRIS-REx to visit. Asteroids less that 200 meters in diameter tend to have high spin rates. Rapid spinning can eject materials from an asteroid’s surface, which then pose a threat for any spacecraft that comes too close.
Finally, Bennu is rich in carbon and its composition is though to have remained unchanged since it formed some 4 billion years ago. As an ancient relic, Bennu can provide important clues about the formation and evolution of our solar system, and the conditions that led the Earth to become habitable for life as we know it.
OSIRIS-REx is currently scheduled to launch in 2016.