Enlarge / NASA’s Psyche spacecraft is the centerpiece of a $1.23 billion mission to explore a kind of asteroid that’s never been visited before. (credit: Stephen Clark/Ars Technica)

TITUSVILLE, Florida—NASA’s Psyche spacecraft is running a year behind schedule before the beginning of its journey to explore a metal asteroid, but mission managers said Friday the probe is essentially ready for launch in less than two months.

The spacecraft is heading for asteroid Psyche, the mission’s namesake, about three times farther from the Sun than Earth. Psyche is the largest metal-rich asteroid in the Solar System, with an average diameter of around 140 miles (226 kilometers). Observations from Earth indicate it’s made mostly of nickel and iron.

The Psyche mission will be the first to explore a metal-rich asteroid, which may be the leftover core of a proto-planet that began forming in the early Solar System more than 4 billion years ago.