Toutatis is a near-Earth asteroid of the Apollo class, with an orbit that crosses Earth’s orbit so that it is classified as a potentially hazardous asteroid. With its 1:4 resonance with Earth’s orbit, it has been observed carefully since 1992 with astronomical telescopes and radar during its close flybys every 4 years. In 2012 it passed by the Earth within just 18 lunar distances, which will be the closest flyby for more than a century. During this flyby the Chinese spacecraft Chang’e 2 observed Toutatis from a distance of less than 1 km and could see details down to a size of a couple of meters.
Toutatis is a stony type asteroid (S (IV)) with a density of about 2.5 g/cm3; it has an elongated shape (4.75 × 1.95 km) and seems to consist primarily of two large pieces, leading to speculation that the asteroid has a rubble-pile structure resulting from a large impact. Toutatis has a slow tumbling rotation with just one rotation per 5.4...