16 Psyche is a large M-type asteroid discovered by the Italian astronomer Annibale de Gasparis on 17 March 1852 and named after the Greek goddess Psyche.
It is estimated to have a mean diameter of approximately 220 kilometres and contains about one percent of the mass of the asteroid belt¹..
It is the largest and most massive of the M-type asteroids, and one of the dozen most massive asteroids¹.
It is also the largest-ever observed M-type asteroid, which is composed mainly of iron and nickel instead of the silicate rocks that make up the majority of other asteroids³.
Historically, it was hypothesized to be the exposed core of a protoplanet, but numerous recent studies have all but ruled that out¹⁴.
Psyche will be explored by a spacecraft of the same name, marking the first time a manmade object will journey to a metallic asteroid.
Launch is planned for no earlier than October 5th, 2023, with an expected arrival in 2029⁴.