Itokawa

Itokawa is a near-Earth asteroid, classified as an Aten-class asteroid, meaning its semi-major axis is less than 1 AU and its orbit crosses Earth's orbit. It was discovered on September 27, 1998, by the LINEAR program. Itokawa is approximately 700 meters long and shaped like a lumpy peanut. It is a C-type asteroid, which are carbonaceous and thought to be among the most primitive bodies in the solar system.

The asteroid is most famous for being the target of Japan's Hayabusa mission. Launched in 2003, Hayabusa successfully reached Itokawa in 2005. The spacecraft studied the asteroid's surface, collected samples, and attempted to return them to Earth. While the mission experienced numerous technical challenges, it ultimately succeeded in bringing back microscopic dust particles from Itokawa in 2010. Analysis of these samples provided valuable insights into the early solar system and the composition of primitive asteroids. Itokawa's irregular shape and low density suggested it is a "rubble pile" asteroid, an aggregate of smaller rocks held together by gravity rather than a solid, monolithic body. This understanding has important implications for planetary formation theories and asteroid impact mitigation strategies.