Key Highlights:
Remember OSIRIS-REx? It’s NASA’s spacecraft that left Earth two years ago to explore Bennu, an asteroid believed to hold crucial information regarding our origin. When we checked its status in August last year, the spacecraft had begun taking its first photos of the asteroid when it was 2 million kilometres away. Now, OSIRIS-REx is closely orbiting the asteroid after a record-breaking manoeuvre. In the following months, we’ll learn more about the asteroid’s physical details.
About an hour after we rung in the new year in India (December 31 at 2:43 PM EST), OSIRIS-REx executed a single, eight-second burn of its thrusters to put itself into a close orbit around Bennu. As it did that, OSIRIS-REx broke a space exploration record and made Bennu the smallest object ever to be orbited by a spacecraft. Currently circling the asteroid at a slow but steady pace, OSIRIS-REx finished its first orbit around the asteroid and marked “a leap for humankind”, remarks NASA in its news release.
OSIRIS-REx will maintain a tight altitude of 1.75 kilometres from the asteroid’s centre, which is the closest any spacecraft has been to a celestial body since May 2016, when the Rosetta spacecraft orbited 7 kilometres from the centre of the comet 67P/Churyumov-Gerasimenko. According to NASA, this distance from Bennu is necessary to remain locked in orbit as the asteroid has a gravitational force only 5-millionths as strong as Earth’s. OSIRIS-REx is scheduled to orbit Bennu till mid-February at a relaxed 62 hours per orbit.
“Our orbit design is highly dependent on Bennu’s physical properties, such as its mass and gravity field, which we didn’t know before we arrived,” commented Mike Moreau, OSIRIS-REx’s Flight Dynamics System Manager. With OSIRIS-REx closely orbiting the asteroid that’s 110 million kilometres away from us, NASA intends to improve its detailed models for Bennu’s gravity field, thermal properties, spin rate, and orientation using the information it can get. OSIRIS-REx is scheduled to bring back a sample of the asteroid back to Earth sometime in 2023.
Cover image courtesy: NASA
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