One of the most intriguing targets in the main asteroid belt, Psyche is a giant metal-rich asteroid, about three times farther away from the Sun than is Earth. Its average diameter is about 140 miles (226 kilometers) – about one-sixteenth the diameter of Earth’s Moon or about the distance between Los Angeles and San Diego.
Psyche might be the partial core of a shattered planetesimal – a small world the size of a city or small country that is the first building block of a planet. If it is, asteroid Psyche can offer a close look at the interior of terrestrial planets like Earth which is normally hidden beneath layers of mantle and crust.
Astronomers on Earth have studied Psyche in visible and infrared wavelengths, as well as radar, which suggests Psyche is shaped somewhat like a potato.
Psyche orbits the Sun between Mars and Jupiter at a distance ranging from 235 million to 309 million miles (378 million to 497 million kilometers) from the Sun. That’s 2.5 to 3.3 Astronomical Units (AU), with 1 AU being the distance between Earth and the Sun. Psyche takes about five Earth years to complete one orbit of the Sun, but it takes just over four hours to rotate once on its axis (a Psyche “day”).
This intriguing asteroid is now the primary target of NASA's planned Psyche mission. The Psyche spacecraft is targeted to travel to the asteroid using solar-electric (low-thrust) propulsion, following a Mars flyby and a gravity assist.
Once in orbit, the spacecraft will map and study Psyche using a multispectral imager, a gamma-ray and neutron spectrometer, a magnetometer, and a radio instrument (for gravity measurement). The mission’s goal is, among other things, to determine whether Psyche is indeed the core of a planetesimal.
How Asteroid Psyche Got Its Name
Psyche was discovered by Italian astronomer Annibale de Gasparis on March 17, 1852. He named the asteroid for Psyche, the Greek goddess of the soul who was born mortal and married Eros (Roman Cupid), the god of Love.