NASA's OSIRIS-REx entered the orbit of the asteroid Bennu on New Year's Eve, setting two new records for the U.S. space agency.
Bennu, which has the size of only 500 meters across, is now the smallest celestial body to be orbited by a spacecraft ever. The record was previously held by the asteroid Ryugu which was orbited by the Japan Aerospace Exploration Agency (JAXA) Hayabusa 2.
OSIRIS-REx is also orbiting the asteroid barely a mile above its surface, the closest orbit ever. The record was previously held by the Rosetta spacecraft, which orbited the comet 67P/Churyumov-Gerasimenko about four miles from its center.
OSIRIS-REx Enters The Orbit Of Asteroid Bennu
The team behind the mission carried out the task on Dec. 31, at 2:43 p.m. OSIRIS-REx made a single, eight-second burn of its thrusters to enter the orbit of the asteroid located 70 million miles away from Earth.
"The team continued our long string of successes by executing the orbit-insertion maneuver perfectly," stated Dante Lauretta, the principal investigator behind OSIRIS-REx.
Entering the orbit of Bennu is a major achievement for Lauretta and his team. The gravity of the asteroid is so weak that it can barely keep the spacecraft in a stable orbit.
"The gravity of Bennu is so small, forces like solar radiation and thermal pressure from Bennu's surface become much more relevant and can push the spacecraft around in its orbit much more than if it were orbiting around Earth or Mars where gravity is by far the most dominant force," explained Dan Wibben, the Maneuver and Trajectory Design lead behind OSIRIS-REx.
The spacecraft is scheduled to orbit around Bennu until mid-February and to study, in sharper focus, the physical details of the asteroid. Scientists also hope to further assess the mass and gravity of the asteroid in preparation for the next phase of the mission.
OSIRIS-REx launched on Sept. 8, 2016, from Cape Canaveral Air Force Station. After a two-year journey, it arrived at Bennu in December last year and flew in formation alongside the asteroid for the past few weeks.
The spacecraft's primary goal is to collect samples from the surface of the asteroid and return them back to Earth. NASA will attempt a brief touchdown in 2020.
The OSIRIS-REx mission is scheduled to return to Earth to deliver samples from the surface of Bennu in Sept. 2023. Scientists are hoping that the asteroid can help give insight into the evolution of the Solar System and, perhaps, shed light on the origin of life on Earth.