Hayabusa2's new challenge is more difficult than expected

The descent of the Japanese Hayabusa2 probe onto a small asteroid, scheduled for 2031, could be much more difficult than expected: new observations coordinated by astronomer Toni Santana-Ros of the University of Alicante in Spain andpublished in Nature Communications, made also thanks to the powerful Very Large Telescope of the European Southern Observatory in Chile, indicate that the asteroid is just 11 meters wide, three times smaller than expected, and is rotating much faster than previously thought.

"We discovered that the object is actually completely different from what had been previously described," said Santana-Ros, referring to asteroid 1998 KY26, which had long been identified as the next target for Hayabusa2, the spectacular mission from the Japanese space agency JAXA that between 2018 and 2019 collected samples from the asteroid Ryugu, which were then sent back to Earth. After that first mission, which saw the probe collect fragments of the asteroid using a sort of proboscis, it was decided to extend the mission by targeting a new asteroid, this time much smaller than Ryugu, 900 meters in diameter. Data indicated that the new target had a diameter of about 30 meters and completed a rotation in about 10 minutes, but the new observations indicate that the object is much smaller and faster: just 11 meters and a rotation of 5 minutes.

"The surprising thing," added Santana-Rios, "is that we discovered that the asteroid's size is comparable to that of the spacecraft that will visit it." These characteristics make the Hayabusa2 mission even more complex, but at the same time even more interesting from a scientific standpoint, as it will study a completely new object, perhaps very different from Ryugu, which was a sort of aggregate of many rocks and debris. The authors state that it cannot be ruled out that 1998 KY26 is actually a single solid piece of rock that may have originated from a fragment of a planet or another asteroid.