25143 Itokawa
25143 Itokawa (provisional designation 1998 SF36) is a sub-kilometer near-Earth object of the Apollo group and a potentially hazardous asteroid. It was discovered by the LINEAR program in 1998 and later named after Japanese rocket engineer Hideo Itokawa. The peanut-shaped S-type asteroid has a rotation period of 12.1 hours and measures approximately 330 meters (1,100 feet) in diameter. Due to its low density and high porosity, Itokawa is considered to be a rubble pile, consisting of numerous boulders of different sizes rather than of a single solid body.
Image of Itokawa from the Hayabusa spacecraft | |
| Discovery | |
|---|---|
| Discovered by | LINEAR |
| Discovery site | Lincoln Lab's ETS |
| Discovery date | 26 September 1998 |
| Designations | |
MPC designation | (25143) Itokawa |
| Pronunciation | /ˌiːtoʊˈkɑːwə/ Japanese: [itoꜜkawa] |
Named after | Hideo Itokawa |
Alternative designations | 1998 SF36 |
Minor planet category |
|
| Orbital characteristics | |
| Epoch 27 April 2019 (JD 2458600.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 20.38 yr (7,443 d) |
| Aphelion | 1.6951 AU |
| Perihelion | 0.9532 AU |
Semi-major axis | 1.3241 AU |
| Eccentricity | 0.2801 |
Orbital period (sidereal) | 1.52 yr (557 d) |
Mean anomaly | 288.88° |
Mean motion | 0° 38m 48.48s / day |
| Inclination | 1.6214° |
Longitude of ascending node | 69.081° |
| 162.82° | |
| Earth MOID | 0.0131 AU (5.10 LD) |
| Physical characteristics | |
| Dimensions | 535 m × 294 m × 209 m |
Mean diameter | 313 m 330 m 350 m |
| Mass | (3.51±0.105)×1010 kg (3.58±0.18)×1010 kg |
Mean density | 1.9±0.13 g/cm3 1.95±0.14 g/cm3 |
Synodic rotation period | 12.132 h |
| 0.23 0.283±0.116 0.36±0.22 0.53 | |
| |
| 18.61 · 18.95 (R) 19.00 · 19.2 19.48 · 19.51±0.09 | |
It was the first asteroid to be the target of a sample-return mission, of the Japanese space probe Hayabusa, which collected more than 1500 regolith dust particles from the asteroid's surface in 2005. Since its return to Earth in 2010, the mineralogy, petrography, chemistry, and isotope ratios of these particles have been studied in detail, providing insights into the evolution of the Solar System. Itokawa was the smallest asteroid to be photographed and visited by a spacecraft prior to the DART mission to Dimorphos in 2022.