On Sunday afternoon, OSIRIS-REx was less than 20 miles from the asteroid, which is about 76 million miles from Earth even in its orbit around the Sun. The vehicle will span the remaining distance to Bennu after another firing of its engines, which will closely monitor the team.
The spacecraft – a roughly cube-shaped spacecraft about two meters apart on each side – will spend about a year surveying and mapping Bennu If all goes well, the ship will lift its 11-foot robot arm in 2020 for a few seconds lower the surface of the 1,600 foot wide asteroid to absorb a sample of regolith (the dust and pebbles that make up the asteroid)
The sample will return to Earth for investigation and is expected to arrive in September 2023. It will be the largest sample taken out of space since Apollo time, and the first sample of an asteroid ever to be brought to Earth from a US space mission.
"OSIRIS-REx and Hayabusa 2 are escort missions," Dante Lauretta, a planetary scientist at the University of Arizona and senior investigator of the OSIRIS REx mission, said in September. "We work together to understand the history of the solar system."
The mission of OSIRIS-REx is to improve our understanding of asteroids as well as the growth and evolution of our solar system to give insights into the origin of life. The seven-year, $ 800 million mission is also designed to help assess the viability of asteroid mining and help scientists find ways in which large asteroids can collide with Earth.
Bennu, one of 700,000 known asteroids in the solar system The system is considered potentially dangerous because of the risk of it colliding with Earth in the late 22nd century.