25143 Itokawa
Asteroid· orbits the Sun
Itokawa is a small, peanut-shaped stony asteroid — a rubble pile of loosely bound fragments — sampled by Japan's Hayabusa in 2005, the first asteroid sample returned to Earth.
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Key facts
Radius
0.165 km
Distance from Sun
1.32 AU
Orbital period
556.5 days
Eccentricity
0.2802
Rotation
12.13 hours
Science
Physical
- Mean radius
- 0.165 km
- Mass
- 3.15 × 10¹⁰ kg · 0.000000000000429 Moon masses
- Density
- 1,672 kg/m³ · 1.7× water
- Computed from mass and radius
- Rotation period
- 12.13 hours
Orbital
- Semi-major axis
- 1.32 AU
- From catalogued orbital elements (MPC)
- Eccentricity
- 0.2802
- From catalogued orbital elements (MPC)
- Inclination
- 1.62 °
- From catalogued orbital elements (MPC)
- Orbital period
- 556.5 days
- From catalogued orbital elements (MPC)
- Perihelion
- 0.953 AU
- Computed from the orbital elements
- Aphelion
- 1.7 AU
- Computed from the orbital elements
- Mean orbital velocity
- 25.9 km/s
- Computed from the orbital elements
Discovery
- Discovered
- September 26, 1998
- Discoverer
- the LINEAR survey
Composition
- Make-up
- An S-type rubble pile of silicate rock fragments with little internal cohesion.
Radiation & temperature
- Insolation
- 0.57 S⊕ · 57% of the sunlight Earth receives
- Computed from the distance to the Sun (inverse-square; Earth's sunlight = 1), before any atmosphere.
- Geometric albedo
- 0.29
- Geometric (V-band) albedo (Hayabusa).
- Equilibrium temperature
- 222 K (-51 °C)
- Computed from albedo + distance from the Sun (airless black body); uses the geometric albedo as an estimate
Discovery & history
- Discovered
- September 26, 1998
- By
- the LINEAR survey
- Method
- Photographic plates
- Name
- The Japanese rocketry pioneer Hideo Itokawa, father of Japan's space programme.
Itokawa is a tiny, elongated near-Earth asteroid found in 1998. A loosely-bound 'rubble pile' rather than a solid rock, it became the target of Japan's Hayabusa mission, which in 2005 became the first spacecraft to land on an asteroid and, in 2010, the first to return a sample of one to Earth.
- 2005HayabusaSample return
First mission to land on an asteroid and return a sample of one to Earth (2010).
Images
Images from open archives · credit shown per image