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25143 Itokawa
Details
25143 Itokawa is the small near-Earth asteroid that Japan's Hayabusa spacecraft landed on in 2005, scooping up grains and returning them to Earth in 2010 – the first sample ever brought back from an asteroid. Hayabusa revealed it to be a rubble pile, a loose heap of fragments held together by gravity rather than a single solid rock.
25143 Itokawa matters because it is the first asteroid humanity ever brought home a piece of. Japan's Hayabusa spacecraft reached this tiny near-Earth body, touched down on its surface, and despite a string of technical failures managed to return a capsule of grains to Earth in 2010. Those microscopic particles were the first asteroid sample ever placed under a laboratory microscope.
What makes Itokawa scientifically important is its structure. Hayabusa's images showed almost no impact craters and a surface strewn with boulders and gravel, evidence that Itokawa is not a solid chunk of rock but a 'rubble pile' – a loose aggregate of fragments bound together only by their mutual gravity. The returned grains confirmed it was once part of a larger, heated parent body that was later shattered and partly reassembled.
That is why Itokawa belongs on this scale. It is only about half a kilometer long, yet it rewrote how we picture small asteroids: not as monolithic stones but as fragile, porous piles. Itokawa turned the rubble-pile idea from theory into something we have held in our hands.
234m
Key facts
- Category
- Asteroids
- Object class
- S-type near-Earth asteroid
- Mass
- ~35 billion tonnes
- Scale fact
- 535 mmaximum extent
- Estimated age
- ~4.5 billion years
- Composition
- Silicate rock (rubble pile)
Scale context
Where 25143 Itokawa sits on the full axis
By size on the journey, 25143 Itokawa sits between Dimorphos and 101955 Bennu. The band below compares 25143 Itokawa with nearby S-type near-Earth asteroid objects so the size jump stays easy to read.
Shared physical scale
26.0km
Together, these objects make the size change around 25143 Itokawa easy to compare at a glance.
Sources
References for 25143 Itokawa
Measurements and descriptive context are compiled by the Scale of Space team from the references below. If you find an error, please let us know.
Between the smallest and the largest, perspective is everything.
About
Scale of Space is a scroll-based journey through the universe, placing objects on a single logarithmic scale so you can compare size across an unbroken range.
Guides turn parts of that scale into curated essays, while focused views let you explore the same range through specific groups of objects.