NASA's Osiris-Rex spacecraft has now maneuvered into an orbit that takes it to the surface of Bennu, a 70-mile-wide asteroid diamond.
The orbit sets a record of the interplanetary journey. The asteroid around a square mile is now the smallest body ever orbiting the spacecraft, and the spacecraft follows the closest orbit around the celestial body.
Bennu defeated the comet 67P / Churyumov-Gerasimenko, a 2.5-mile-comet comet that rolled the European Space Agency's roses from 2014 to 2016. OSIRIS-REx orbits about one kilometer from the center of Bennu, while Rosetta's orbit is 4 miles from the center of the comet.
Today's critical criticism of eight seconds from the OSIRIS-REx guns, built by Aerojet Rocketdyne in Redmond, Washington, was perfectly done, said Arizona University scientist Dante Laurette, who is the chief investigator of the mission.
"Entry into orbit around Bennu is an amazing achievement our team has been planning for years," Laurette said in a press release.
OSIRIS-Reks held a meeting with Bennu on December 3 after a two-year trip. Since the arrival of the spacecraft, the mission team carefully monitored the mass distribution of the asteroid near Earth and dropped the orbit, step by step.
The spacecraft should follow such a close orbit, partly because the gravitational pull of Bennu is so weak. The retreating of the Earth is about 200,000 times stronger, says the team's mission. Proximity also facilitates the task that lies ahead for OSIRIS-REx: mapping the surface of the asteroid in detail during a series of leisurely 62-hour orbits.
Orbit will need to be adjusted periodically for stability, said Dan Vibben, Olympic Manager of OSIRIS-REx at KinetX Aerospace in Simi Valley, California.
"Bennu's weight is so small that forces like solar radiation and heat pressure from Bennu surface become much more relevant and can push the spacecraft into their orbit much more than if they circled around the Earth or Mars, where gravity is by far the most dominant force "he explained.
In February, the spacecraft will take a series of even closer flybys to look for the best spot for a sample during a series of touch and window maneuvers scheduled for 2020.
The name of OSIRIS-REx is an acronym that stands for "origin, spectral interpretation, resource identification, security, regulatory researcher". The objectives of the mission include characterizing the composition of the asteroid to shed more light on the composition of the primordial material of the solar system; identifying resources that could be useful to future travelers in space; and helping scientists find out how to redirect potentially threatening asteroids if needed.
Samples collected from OSIRIS-REx should be returned to the Earth for a laboratory study in 2023.