Itokawa is an S-type near-Earth asteroid, numbered 25143. This irregular object has been the first asteroidal target for a sample return mission: the JAXA Hayabusa-1 mission. It has established that Itokawa is very small (530 × 290 × 210 m) and has a density of about 1,900 kg/m−3, leading to a rather high porosity. It presents rough terrains scattered with boulders and smooth featureless areas, resulting from fine dust accumulated in local gravitational lows. Its shape suggests that it is a contact binary (as the nucleus of comet Hartley 2). Its density could indicate that it is built from loose-packed rocks, held together by their gravity. Samples of the asteroid have been brought back to Earth and are under analysis.