1998 KY26
Key facts
- What it is
- Small near-Earth asteroid (Apollo group)
- Size
- About 11 m across
- Discovered
- 1998, by the Spacewatch survey
- Spacecraft
- Hayabusa2 arrival planned for 2031
- Orbit group
- Apollo
- Average distance from the Sun
- 1.23 au (about 180 million km)
- Time to go round the Sun
- 498 days
- Closest and farthest from the Sun
- 0.98 to 1.47 au
- Tilt of its orbit
- 1.5°
- Closest its orbit comes to Earth's
- 380,000 km (1 times the Moon's distance)
- Spins once every
- 5.4 minutes
An au (astronomical unit) is Earth's average distance from the Sun, about 150 million km. Orbit figures are from open tracking data, figures last updated 1 Nov 2026.
1998 KY26 is a tiny asteroid that will become the smallest ever visited by a spacecraft. It was discovered in June 1998 by the Spacewatch survey telescope in Arizona, and it is the final target of Japan's Hayabusa2 spacecraft, which already returned samples from the asteroid Ryugu in 2020 and is now on an extended journey. It is planned to arrive in 2031.
For many years 1998 KY26 was thought to be about 30 metres across. Observations published in 2025, made with some of the world's largest telescopes when the asteroid passed relatively close to Earth, showed it is only about 11 metres wide, roughly the size of a bus or a small house. They also found it spins once about every five minutes, twice as fast as earlier estimates and one of the fastest rotations known.
Its surface is bright, and the fast spin suggests it may be a single solid piece of rock rather than a loose rubble pile, because loose material would be flung off at that speed unless held together by other forces. That makes landing much harder, and the mission team is now studying how a touchdown could be done safely.
Small asteroids like this are by far the most numerous, and objects of this size reach Earth's atmosphere from time to time. The 2013 Chelyabinsk fireball was caused by one about 18 metres wide. Studying 1998 KY26 up close will help scientists understand what such bodies are made of and how they would break up in the air. It poses no risk itself.
Coming close to Earth
Its next passes within about 30 million km of Earth, worked out from its orbit. Each one is a safe miss.
| Date | Distance | In Moon distances |
|---|---|---|
| 24 May 2039 | 16,000,000 km | 42 |
| 5 Sept 2058 | 13,000,000 km | 34 |
| 30 Aug 2073 | 7,200,000 km | 19 |
| 4 Jun 2099 | 4,100,000 km | 11 |
| 27 Aug 2118 | 4,100,000 km | 11 |
| 31 Aug 2133 | 5,800,000 km | 15 |