Short answers, pulled from the story.
25143 Itokawa is a sub-kilometer near-Earth asteroid in the Apollo group, classified as potentially hazardous. It measures roughly 330 meters across, is peanut-shaped, and completes one orbit of the Sun every 557 days. Scientists consider it a rubble pile rather than a solid body, held together by its own gravity rather than internal rock strength.
25143 Itokawa was discovered on the 26th of September 1998 by the Lincoln Near-Earth Asteroid Research (LINEAR) program at Lincoln Laboratory's Experimental Test Site near Socorro, New Mexico. The Minor Planet Center published the official name on the 6th of August 2003.
Hideo Itokawa (1912-1999) is regarded as the father of Japanese rocketry. Asteroid 25143 Itokawa was named in his memory to honor his role in building Japan's space program, with the naming made official by the Minor Planet Center on the 6th of August 2003.
Hayabusa made two landing attempts on Itokawa, on the 20th and the 25th of November 2005, ultimately collecting more than 1,500 regolith dust particles from the asteroid's surface. The Japan Aerospace Exploration Agency confirmed on the 16th of November 2010 that the material was genuinely from Itokawa.
Itokawa is a rubble pile composed of loosely packed boulders and fragments held together by gravity. Its dust matches the composition of low-total-iron, low metal ordinary chondrites, suggesting the asteroid formed from the interior of a larger body that broke apart. Density estimates across different sections of the asteroid range between 1.8 and 2.9 grams per cubic centimeter.
Multiple research teams reported water in Itokawa dust particles beginning in 2018. One group traced hydroxyl and water in olivine grain rims to hydrogen atoms implanted by the solar wind, and a 2020 study found water and organics together in a grain nicknamed Amazon. The asteroid's overall water content was estimated to be comparable to Earth's bulk silicate water, leading researchers to describe Itokawa as a water-rich asteroid.