While we were all busy watching the Perseverance rover on its journey to Mars, NASA’s Asteroid Sample Mission has put them together for their big moment. The Origins, Spectral Interpretation, Source Identification, Security, Regolith Explorer (OSIRIS-REx for short) has completed its definitive surface test approach. Next time it lands, OSIRIS-REx will search for pieces of the asteroid Bennu for return to Earth.
NASA launched OSIRIS-REx in 2016, sending it away to distinguish 101955 Bennu, a carbonaceous asteroid about 1,610 feet (490 meters) in diameter. Bennu gets really close to the earth at points in its orbit – there is even a small chance that it could have an impact on the earth in the coming centuries. At present it is safely out of the way about 2 AU away (an AU is the distance between Earth and the Sun).
OSIRIS-REx rendezvoused with Bennu in 2018, and the team set out to work on finding a landing zone. NASA faced the same problem as the Japanese Hayabusa2 team – Bennu was much more kneeling than expected. To collect a sample, OSIRIS-REx must make contact with the surface, which is dangerous with uneven surfaces and rocky prominence everywhere. Finally, NASA selected several potential sites, and named them after birds. The Nightingale site, located in a crater near the north pole of the asteroid, ruled.
On August 11, OSIRIS-REx completed its second dress rehearsal for the real deal. The spacecraft fired its engines to leave the ‘safe living space’ and sank to 125 meters (125 meters) above the surface. On the way down, OSIRIS-REx coincided with Bennu’s rotation and reached a height of just 131 feet (40 meters) above Nightingale. In the video above you can see that Nightingale comes into view at the top of the frame near the end. At that point, the engines shot up again to move OSIRIS-REx back into a safe path.
With the exercises completed, the team can focus all its efforts on the October 20 sampling operation. On that day, OSIRIS-REx will drop the entire sink and kiss Bennu’s surface with his sampling arm. A puff of nitrogen gas will (hopefully) launch particles of Bennu into the sample container. NASA hopes to collect about 60 grams of Bennu’s material. After the collection, OSIRIS-REx will return to Earth with the precious cargo. The return capsule is currently scheduled to land in September 2023.
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