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The Psyche Mission: Visiting a metal asteroid

The first mission to the metal world 16 Psyche will map features, structure, composition, and magnetic field, and examine a landscape unlike anything explored before. Psyche will teach us about the hidden cores of the Earth, Mars, Mercury and Venus.
The NASA spacecraft known as Psyche will visit a mysterious metal asteroid of the same name. (Image credit: SSL/Peter Rubin)

Psyche is a NASA mission expected to launch in 2022 that will explore a 140-mile-wide (225 kilometers) metallic asteroid called 16 Psyche. No spacecraft has ever visited an object like 16 Psyche, which is thought to be the exposed core of a demolished planet. The mission is expected to provide important insights into planetary formation. 

Along with a mission called Lucy that will visit primordial asteroids near Jupiter, Psyche was approved in January 2017 as part of NASA's Discovery program. "This is what Discovery Program missions are all about — boldly going to places we've never been to enable groundbreaking science," Thomas Zurbuchen, associate administrator for NASA's Science Mission Directorate in Washington, D.C., said in a statement at the time.

Related: NASA's getting ready to explore the corpse of an ancient planet in the asteroid belt

An artist's depiction of the metal-rich asteroid Psyche, which a NASA spacecraft will visit later this decade.

An artist's depiction of the metal-rich asteroid Psyche. (Image credit: Maxar/ASU/P. Rubin/NASA/JPL-Caltech)

Psyche: the metal asteroid

The asteroid 16 Psyche, also referred to as simply "Psyche," was only the 16th asteroid ever discovered according to an informational page about the mission from Arizona State University (ASU). It was spotted in 1852 by an Italian astronomer named Annibale de Gasparis, who named it for the ancient Greek goddess of the soul.

Psyche has a mass of about 440 billion billion pounds (220 billion billion kilograms), making it 0.03% the mass of our moon, according to a 2002 paper in Astronomy and Astrophysics. It's the eleventh most massive known asteroid in the solar system — though only a few hundredths of the mass of behemoths like Ceres and Vesta.

Related: Why NASA is sending a spacecraft to a metal asteroid called 'Psyche'

Unlike most bodies in the solar system, which are composed of mainly rock, ice or gas, the Massachusetts-sized Psyche is mostly metal — as much as 95% nickel and iron, which is similar to the Earth's core. That metallic nature makes the asteroid a compelling subject as researchers speculate about how it could have formed. 

In one hypothetical scenario, 16 Psyche was once part of a protoplanet in the early solar system whose internal layers separated out into rocky mantle and iron core, according to ASU. Multiple violent collisions billions of years ago may have cracked this entity open and stripped away its exterior, leaving only a misshapen metal lump behind. Much of the Psyche spacecraft's mission will be scanning the asteroid for clues that either support or reject this story.

Artist's concept of the Psyche spacecraft, a proposed mission for NASA's Discovery Program that will launch in 2023 to explore an object thought to be a stripped planetary core.

Another artist's concept of the Psyche spacecraft above a metal asteroid. (Image credit: NASA/JPL-Caltech)

Psyche: the NASA spacecraft

Psyche (the probe) is 81 feet (24.76 m) long and 24 feet (7.34 m) wide, making it roughly the size of a tennis court with its solar panels extended, according to ASU. The body of the spacecraft, where all its instruments are, is about as big as a golf cart.

ASU lists several instruments that the spacecraft will carry.  They include two high-resolution cameras and a spectrometer to determine the asteroid's composition. In addition, Psyche will sport a magnetometer to check if the body has a remnant magnetic field and an instrument to measure the asteroid's gravitational field with high precision. The spacecraft is also equipped with sophisticated new laser communication technology that NASA hopes to use in future missions. 

After it is launched in August 2022 atop a SpaceX Falcon Heavy rocket, the probe Psyche will use low-thrust solar electric propulsion to conduct a gravity assist past Mars in 2023, and is expected to arrive at its target in 2026. 

Related: NASA mission to weird metal asteroid Psyche remains on track for 2022 launch

The mission plan calls for the Psyche spacecraft to spend 21 months orbiting the asteroid while capturing the first images ever taken of a mainly metal body. Using its instruments, the probe will map and study the asteroid to help researchers determine how it came to be.

Data from Psyche will help astronomers figure out how terrestrial planets form. It is difficult to observe the core of rocky planets like Earth, because that structure lies far below the planet's mantle and crust. By studying 16 Psyche up close, researchers hope to better understand how collisions, accretion and time work to create worlds like our own. 

Additional resources

Adam Mann is a journalist specializing in astronomy and physics stories. His work has appeared in the Wall Street Journal, Wired, Nature, Science, New Scientist, and many other places. He lives in Oakland, California, where he enjoys riding his bike. Follow him on Twitter @adamspacemann.

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