Astronomers have found that asteroid 1998 KY26, the goal of Japan’s Hayabusa2 prolonged mission, is much smaller and faster-spinning than beforehand thought.
Astronomers have carried out a brand new examine of the asteroid 1998 KY26 utilizing observatories throughout the globe, together with the European Southern Observatory’s Very Large Telescope (ESO’s VLT). Their findings show that the asteroid is nearly three times smaller than earlier estimates and spins much faster than expected.
This small but fast-moving object has been chosen as the 2031 destination for Japan’s Hayabusa2 extended mission. With only six years remaining until the spacecraft arrives, the updated measurements provide crucial details to help plan operations at the asteroid.
“We found that the reality of the object is completely different from what it was previously described as,” says astronomer Toni Santana-Ros, a researcher from the University of Alicante, Spain, who led a study on 1998 KY26 published today in Nature Communications.
The new observations, combined with previous radar data, have revealed that the asteroid is just 11 meters wide, meaning it could easily fit inside the dome of the VLT unit telescope used to observe it (see image below). It is also spinning about twice as fast as previously thought: “One day on this asteroid lasts only five minutes!” he says. Previous data indicated that the asteroid was around 30 meters in diameter and completed a rotation in 10 minutes or so.

A Challenge for Hayabusa2
“The smaller size and faster rotation now measured will make Hayabusa2’s visit even more interesting, but also even more challenging,” says co-author Olivier Hainaut, an astronomer at ESO in Germany. This is because a touchdown maneuver, where the spacecraft ‘kisses’ the asteroid (see video below), will be more difficult to perform than anticipated.
1998 KY26 is set to be the final target asteroid for the Japanese Aerospace eXploration Agency (JAXA)’s Hayabusa2 spacecraft. In its original mission, Hayabusa2 explored the 900-metre-diameter asteroid 162173 Ryugu in 2018, returning asteroid samples to Earth in 2020.
With fuel remaining, the spacecraft was sent on an extended mission until 2031, when it’s set to encounter 1998 KY26, aiming to learn more about the smallest asteroids. This will be the first time a space mission encounters a tiny asteroid — all previous missions visited asteroids with diameters in the hundreds or even thousands of meters.
This animation reveals the landing manoeuvre that Japan’s Hayabusa2 spacecraft is more likely to carry out when it reaches its goal in 2031, in a quick encounter with the asteroid 1998 KY26. Now {that a} new examine has proven that this asteroid is roughly thrice smaller than beforehand anticipated, and spinning twice as quick, this process could also be tougher to conduct. Credit score: ESO/M. Kornmesser. Asteroid: T. Santana-Ros et al. Hayabusa2 mannequin: SuperTKG (CC-BY-SA)
Observing a Faint Goal
Santana-Ros and his crew noticed 1998 KY26 from the bottom to assist the preparation of the mission. As a result of the asteroid could be very small and, therefore, very faint, learning it required ready for an in depth encounter with Earth and utilizing giant telescopes, like ESO’s VLT in Chile’s Atacama Desert.
The observations revealed that the asteroid has a brilliant floor and certain consists of a strong chunk of rock, which can have originated from a bit of a planet or one other asteroid. Nevertheless, the crew couldn’t fully rule out the chance that the asteroid is made up of rubble piles loosely sticking collectively. “We’ve got by no means seen a ten-meter-sized asteroid in situ, so we don’t actually know what to anticipate and the way it will look,” says Santana-Ros, who can be affiliated with the College of Barcelona.
“The wonderful story right here is that we discovered that the scale of the asteroid is akin to the scale of the spacecraft that’s going to go to it! And we had been in a position to characterise such a small object utilizing our telescopes, which signifies that we will do it for different objects sooner or later,” says Santana-Ros. “Our strategies may have an effect on the plans for future near-Earth asteroid exploration and even asteroid mining.”
“Furthermore, we now know we will characterize even the smallest hazardous asteroids that would impression Earth, such because the one which hit close to Chelyabinsk, in Russia in 2013, which was barely bigger than KY26,” concludes Hainaut.
Reference: “Hayabusa2 prolonged mission goal asteroid 1998 KY26 is smaller and rotating sooner than beforehand recognized” by T. Santana-Ros, P. Bartczak, Okay. Muinonen, A. Rożek, T. Müller, M. Hirabayashi, D. Farnocchia, M. Micheli, R. E. Cannon, M. Brozović, O. Hainaut, D. Oszkiewicz, A. Okay. Virkki, L. A. M. Benner, A. Campo Bagatin, P. G. Benavidez, A. Cabrera-Lavers, C. E. Martínez-Vázquez and Okay. Vivas, 18 September 2025, Nature Communications.
DOI: 10.1038/s41467-025-63697-4
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