162173 Ryugu

At a glance

Key points

Japan's Hayabusa2 returned its samples in 2020 and is now heading for a tiny, fast-spinning asteroid.

• Hayabusa2 made an artificial crater to sample it
• Samples contain all five nucleobases
• Hayabusa2 flew past asteroid Torifune in July 2026

Shape and surface

Ryugu is a spinning top with a pronounced equatorial ridge, covered in boulders with almost no fine dust. Hayabusa2 fired a copper projectile into it in 2019 to expose fresh material beneath the space-weathered surface.

A year and a half at Ryugu

Hayabusa2 arrived on 27 June 2018. That September its two MINERVA-II1 hoppers became the first rovers to land on an asteroid, followed by the German–French MASCOT lander. The spacecraft touched down on 22 February 2019, blasted an artificial crater with its impactor on 5 April, and on 11 July touched down again nearby to collect material thrown up from below the surface, the first subsurface sample taken from an asteroid.

What the grains revealed

The returned particles are the closest match yet to CI chondrites, rare meteorites whose make-up is nearest to the Sun's own. They are rich in water-bearing clay minerals, reflect only about 2% of light and are about 46% empty space. Material this fragile seldom survives a fall through Earth's atmosphere, which helps explain why carbon-rich asteroids are under-represented in meteorite collections.

Next stop: 1998 KY26

After its 5 July 2026 flyby of the roughly 450 m asteroid Torifune, Hayabusa2 has Earth swing-bys planned in 2027 and 2028 and is scheduled to reach 1998 KY26 in 2031. A 2025 study found KY26 is only about 11 m across, nearly three times smaller than thought, and spins once every 5 minutes 21 seconds. That makes any touchdown far harder; if landing proves impossible, a close flyby would still return the first detailed look at such a tiny asteroid.

What we still don't know

How Ryugu and Bennu, so similar in shape, came to spin themselves into spinning tops.

Missions

1. 2014–

   Hayabusa2

   JAXAActive

   Returned Ryugu samples in 2020; flew past asteroid Torifune 5 Jul 2026, bound for 1998 KY26 in 2031.

Related entries

• 101955 BennuRubble-pile asteroid sampled by OSIRIS-REx

Sources

1. DLR: Hayabusa2 flyby of the mini-asteroid Torifune (Jul 2026) (opens in a new tab)
2. Santana-Ros et al. 2025, 1998 KY26 is smaller and faster-rotating, Nature Communications (opens in a new tab)
3. JPL Small-Body Database: 162173 Ryugu (opens in a new tab)
4. The Planetary Society: Hayabusa2 (opens in a new tab)
5. JAXA Hayabusa2 curation: Ryugu samples (opens in a new tab)
6. JAXA: Hayabusa2 chronology (opens in a new tab)
7. JAXA ISAS: Ryugu is rich in water and organic matter (opens in a new tab)

Last reviewed 10 Oct 2026 against these sources. Built from public NASA, ESA and JPL data; not affiliated with or endorsed by any agency.