After two years in space, NASA’s OSIRIS-REx probe has reached its destination: the asteroid Bennu. The rendezvous is already a significant achievement, but the mission is far from over. Eventually, OSIRIS-REx will graze the surface of Bennu to pick up a tiny bit of material to send back to Earth.
OSIRIS-REx is part of NASA’s New Frontiers program along with Juno and New Horizons. It launched in September 2016 aboard an Atlas V rocket, angling for the encounter with Bennu that occurred on December 3rd. OSIRIS-REx needed just a small burst from its engines to line up with Bennu for the first of several mapping runs.
Later this year, OSIRIS-REx will tighten its path around Bennu to enter into a stable orbit of the asteroid. Currently, the probe is swinging past Bennu at an altitude of 12 miles (19 kilometers). By early next year, the team plans to have OSIRIS-REx passing just 0.87 miles (1.4 kilometers) above the surface of Bennu. From this vantage, the probe can take high-resolution scans of the terrain in preparation for its big moment.
NASA plans to take its time with the mapping and initial science phase of the mission. OSIRIS-REx will orbit and study Bennu for about 18 months at close range, giving scientists a good idea of what its surface is like. In summer 2020, OSIRIS-REx will approach the surface and deploy the touch-and-go-sample acquisition mechanism (TAGSAM), a 10-foot robot arm a small scoop at the end. TAGSAM will make contact with the asteroid for about five seconds. At the same time, a puff of compressed nitrogen will kick up regolith to be captured in the scoop.
#WelcomeToBennu! After two years of travel – and more than a decade of planning and work by my team – I’m here. But Arrival is just the beginning… https://t.co/0bQPUwqUCp
Credit: NASA/Goddard/University of Arizona pic.twitter.com/VyPG3gRRdw
— NASA's OSIRIS-REx (@OSIRISREx) December 3, 2018
OSIRIS-REx could collect up to 4.4 pounds (2 kilograms) of material from Bennu, but it may be as little as a few ounces. We just don’t know enough about the surface composition to say for certain. Whatever it obtains will get packed away in an aerodynamic sample return canister. OSIRIS-REx will be done with its science mission at that point. NASA will simply have to wait for the probe’s orbit to bring it in position to send the sample back to Earth. That should happen around March 2021, and the sample could land on Earth as soon as September 2023.
Scientists believe examining pristine material from objects like Bennu could help us understand the origins of the solar system. Before all that, we’re sure to get some fantastic close-up pictures of the asteroid.
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