// SPACE.COM — SPAZIO & SCIENZA
Japanese probe set for super-close flyby on July 5: 'We're going to discover another beast to put in the zoo of asteroids'
"This is one of the closest asteroid encounters ever attempted by a mission of this class."
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Japan's Hayabusa2 sample-return spacecraft is on target to make one of the closest ever flybys of a near-Earth asteroid in early July, as part of its extended mission campaign.
Hayabusa2 launched in December 2014 and rendezvoused with the asteroid Ryugu four years later. The spacecraft collected samples and delivered them to Earth in 2020, completing its primary objectives. But the hardy spacecraft still has bold plans to deliver new and exciting science data.
The spacecraft has been operating well, despite needing to briefly enter a protective safe mode last year, and now is set to make a flyby of the asteroid Torifune on July 5, Satoshi Tanaka of the Japanese Aerospace Exploration Agency (JAXA) said in a presentation on Hayabusa2 during the 35th Meeting of the NASA Small Bodies Assessment Group (SBAG) on June 11.
The flyby will see Hayabusa2 get within 1 to 10 kilometers (0.62 to 6.2 miles) of Torifune, using its instrument suite to study the roughly 450-meter-wide (1,476 feet) asteroid as it whizzes past at 5.3 kilometers per second (3.3 miles per second).
"This is one of the closest asteroid encounters ever attempted by a mission of this class," Tanaka said. "By combining advanced navigation techniques and the engineering capabilities of Hayabusa2, we have made it possible to achieve a flyby at a distance of only about 1 kilometer."
Torifune was first given the designation 2001 CC21 before being named for a deity from Japanese mythology. Tanaka says the asteroid is somewhat similar to Itokawa — the target of Japan's first Hayabusa mission — but little is known for sure about Torifune, adding a level of uncertainty to this extended mission objective.
"It's still a risky operation, because they had not planned for this," Patrick Michel, the principal investigator for the European Space Agency's Hera asteroid mission and part of the Hayabusa2 science team, told Space.com. "The second thing is that we have a high uncertainty on the size of the object," he added, with the dimensions of the asteroid unknown.
The asteroid could, for example, be a contact binary, according to Michel, in which two separate bodies came together at low velocities. Known contact binary small bodies include the Kuiper belt object Arrokoth, imaged by NASA's New Horizons, and comet 67P/Churyumov-Gerasimenko, described as a "rubber duck" when visited by ESA's Rosetta spacecraft.