Hayabusa2's next asteroid isn't much bigger than the probe

"Japan's Hayabusa2 probe faces a tougher mission after new measurements revealed its target asteroid is nearly three times smaller and spinning about twice as fast as originally estimated. Having scooped up some asteroid material from 162173 Ryugu in 2018, which was returned to Earth in 2020, Hayabusa2 was sent on an extended expedition to another asteroid, 1998 KY26. The probe is due to reach its target in 2031."

"The trip was always going to be a greater challenge. Part of it involves a high-speed flyby of another asteroid, 98943 Torifune, something Hayabusa2's instruments (such as its fixed cameras) weren't designed for, and after this a rendezvous with 1998 KY26. Keeping the spacecraft running for another decade was going to be tough enough, but now, rather than the 30-meter-object the probe was aiming for, recent observations have refined the size down to 11 meters wide."

"Furthermore, rather than spinning once every ten minutes, the asteroid is rotating once every five minutes. Olivier Hainaut, an astronomer at the European Southern Observatory (ESO) in Germany, said: "The smaller size and faster rotation now measured will make Hayabusa2's visit even more interesting, but also even more challenging." Hainaut co-authored a paper in Nature Communications on the subject. ESO has published the observations based on findings from the organization's Very Large Telescope (VLT) in Chile's Atacama Desert, as well as data from other observatories worldwide."

Hayabusa2 returned samples from asteroid 162173 Ryugu collected in 2018 and delivered them to Earth in 2020, then was retasked to visit asteroid 1998 KY26 with arrival planned for 2031. New VLT and other observatory measurements indicate 1998 KY26 is roughly 11 meters across rather than 30 meters, and spins once every five minutes instead of ten. The extended mission includes a high-speed flyby of asteroid 98943 Torifune and a planned rendezvous that may involve firing a tantalum projectile. The smaller size and rapid rotation increase operational, targeting and instrument-challenge risks and may require plan revisions.

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