Hayabusa2 flies past asteroid Torifune
On 5 July 2026 JAXA's Hayabusa2 sped past Torifune, a two-lobed asteroid, at about 5 km/s and observed it up close. The spacecraft now heads for its final target, the tiny asteroid 1998 KY26, in 2031.
The story
At 09:30 UTC on 5 July 2026, the Japanese spacecraft Hayabusa2 flew past the asteroid 98943 Torifune. After completing its main mission of returning samples from the asteroid Ryugu, Hayabusa2 continued on an extended mission called Hayabusa2#, operated by the Japan Aerospace Exploration Agency (JAXA). Torifune, previously known by the provisional designation 2001 CC21, was the first asteroid on that extended route.
This was not a slow, careful approach but a high-speed pass. The spacecraft and the asteroid were moving relative to each other at about 5 km/s, or roughly 18,000 km per hour, so the window for close-up observation was very short. During those moments Hayabusa2 used four instruments together: a telescopic camera, a spectrometer that reveals what the surface is made of, a thermal camera that measures temperature and a laser rangefinder.
Torifune turned out to be a contact binary, an asteroid made of two lobes resting against each other. It measures about 840 m by 340 m, with a mean diameter of about 540 m, and is classified as an S-type asteroid, meaning its surface is dominated by stony minerals. Ryugu, by contrast, is a dark, carbon-rich asteroid, so the same spacecraft and instruments have now examined two quite different kinds of small body.
On 30 July JAXA published its reconstruction of the pass: Hayabusa2 came within about 744 m of Torifune's centre and about 400 m of its surface, only 120 m from the aim point, which JAXA described as the closest flyby of a Solar System body by any spacecraft. JAXA's thermal infrared image was taken from about 10 km away.
Mission goals
At Ryugu, Hayabusa2 spent a long time close to its target and could observe at leisure. A fast flyby is a very different challenge: the cameras have to be pointed accurately at a small, rapidly moving target and the data collected in a very short time. Carrying that out at a few kilometres per second is demanding for both the spacecraft and the people operating it, and the Torifune pass put that capability into practice.
Scientifically, Torifune's shape is the main attraction. How two lobes came to rest gently against each other, and what the join between them looks like, are clues to how small asteroids form and evolve. And because Torifune is a stony S-type asteroid observed with the same instruments that studied carbon-rich Ryugu, the two can be compared directly without worrying about differences between instruments.
The pass was also a rehearsal for Hayabusa2's last target. 1998 KY26 is only about 11 m across, far smaller than Torifune, and it spins far faster. Pointing cameras at a real asteroid and measuring its distance gave the team a chance to check the instruments and the spacecraft's navigation before that arrival. The ability to observe while speeding past could also prove useful whenever a newly found object has to be studied in a short time.
Mission chronology and background
Hayabusa2 launched in December 2014 and reached Ryugu in 2018. It touched down on the surface twice to collect material, and in December 2020 it released a capsule that landed in Australia carrying the samples. Its predecessor, the first Hayabusa, had brought tiny grains from the asteroid Itokawa back to Earth in 2010, and Hayabusa2 was built on that experience.
After the capsule was delivered, the spacecraft still had propellant and working instruments. Rather than retire it, JAXA sent it on the extended Hayabusa2# mission to visit new asteroids. The Torifune flyby is the first result of that extension, and the arrival at 1998 KY26 in 2031 is its final goal.
Torifune is not the first two-lobed body a spacecraft has visited. Itokawa, the target of the first Hayabusa, has a peanut-like shape made of two unequal parts. Comet Churyumov–Gerasimenko, studied by Europe's Rosetta, and Arrokoth, which New Horizons flew past beyond Neptune, are also made of two lobes pressed together. Scientists take the frequency of such shapes as a sign that gentle mergers of small bodies were common.
Other milestones of this mission
- Hayabusa2 reaches tiny 1998 KY26(planned)
Where to see it — sky and simulator
Torifune is far too small to see without a large telescope, and Hayabusa2 itself cannot be seen from Earth. The spacecraft's path is not included in this simulator, so the flyby is not replayed here. Results are released by JAXA as images and data are processed, and because part of the data was still waiting to be downloaded, further releases may follow.
Hayabusa2's next stops are close to home. It is scheduled to fly past Earth in December 2027 and again in June 2028, using Earth's gravity to reshape its orbit, and then to reach its final target, the asteroid 1998 KY26, in July 2031. That asteroid is only about 11 m across and spins once every 5 minutes 21 seconds.
FAQ
Did Hayabusa2 land on Torifune?
No. It only observed the asteroid while speeding past at about 5 km/s. No samples were taken, and Hayabusa2 no longer carries a return capsule.
How close did it get?
According to JAXA's 30 July analysis, about 744 m from the asteroid's centre and about 400 m from its surface, which JAXA described as the closest flyby of any Solar System body so far.
What is a contact binary?
It is an object made of two lobes touching each other so that they move as one body, often looking like a peanut or a snowman. Torifune has this kind of shape.
Where does Hayabusa2 go next?
It will pass Earth in December 2027 and June 2028, then arrive at 1998 KY26, a fast-spinning asteroid about 11 m across, in July 2031.
Related
- Hayabusa2 reaches 1998 KY26
- Tianwen-2 reaches Kamoʻoalewa
- Lucy flies past Eurybates
- Hera arrives at Dimorphos
- DART impact
Times and figures are approximate — verify with official sources when planning travel. Simulation uses J2000 mean elements.