Nasa’s Osiris-Rex spacecraft has achieved orbit around asteroid Bennu. The spacecraft eased into orbit with an eight-second burn of its thruster on 31 December at 19.43 GMT.
Its mission is to survey the small asteroid and then collect a sample of the surface material to send back to Earth for analysis.
Bennu was discovered in September 1999. It is a small, spheroidal near-Earth asteroid with a diameter of around 520 metres. Its surface is composed of carbonaceous compounds whose composition reflects the earliest stages of the solar system’s development, while the Earth and the other planets were forming.
Osiris-Rex stands for origins, spectral interpretation, resource identification, security, regolith explorer. It is now in an orbit around the asteroid with a radius of a mile. Even though the orbit is so small, it takes a leisurely 62 hours to complete a rotation because the gravity at the asteroid is minuscule, just five-millionths the gravity of Earth.
For the next month and a half, the spacecraft team will concentrate on navigating around the asteroid. Then science operations will recommence in late February. During the summer of 2020, the spacecraft will briefly descend to the surface to collect a sample.