Unique asteroid holds clues to the early solar system

At NASA's Jet Propulsion Laboratory, engineers integrate a gamma ray and neutron spectrometer into the agency's Psyche spacecraft. The instrument will help determine the elements that make up its target, an asteroid also named Psyche. Credit: NASA/JPL-Caltech

NASA is preparing to launch the Psyche mission, which is set to explore an asteroid, Psyche, that is believed to be richer in metal than rock or ice. This mission marks the first time the agency has aimed to visit such an asteroid. Psyche is an asteroid in the main asteroid belt, orbiting between Mars and Jupiter. Scientists believe that the asteroid is mostly made of metal and could be a part or all of an early planetary building block that was stripped of its outer rocky shell during the early formation of the solar system. NASA's Psyche mission will orbit the asteroid for two years, taking pictures, mapping the surface, and looking for evidence of an ancient magnetic field. The mission is set for launch in August 2022.

The Unusual Nature of Psyche

The Psyche mission is important because the asteroid is unlike any other that has been studied before. With its metal content, high density, and low concentration of iron oxides, Psyche is particularly intriguing to scientists, who hope to learn more about its origins and formation. Scientists have observed that Psyche does not generate a magnetic field, unlike Earth. However, if Psyche had a magnetic field in the past, it could still be recorded in the asteroid's material today, which would confirm that the asteroid is part of the core of an early planetesimal, the building block of an early planet.

Questions and Theories Surrounding Psyche

Psyche presents a host of mysteries for scientists to explore. Scientists are still unsure where Psyche originated. While it might have formed inside the main asteroid belt, it is also possible that it was born in the same zone as Earth or in the outer solar system, where giant planets like Jupiter reside today. Neither origin story follows a simple path to where Psyche is today, which is 280 million miles (450 million kilometers) from the Sun. Scientists are also puzzled as to why Psyche appears to be low in iron oxides, which are chemical compounds made of iron and oxygen. Mars, Mercury, Venus, and Earth all have iron oxides. The mission's principal investigator, Lindy Elkins-Tanton of Arizona State University, said that there are a lot of basic questions about Psyche that are unanswered. With every detail added from data gathered from Earth, it just becomes harder to make a sensible story. Psyche's story is unique, and scientists will be surprised by what they find when they reach the asteroid.

The Psyche Mission

NASA's Psyche mission hopes to find out more about the asteroid's origins and formation. The mission will rely on a magnetometer, a gamma-ray and neutron spectrometer, and a multispectral imager to gather data. The magnetometer will determine whether Psyche is still magnetized, which would confirm that the asteroid is part of the core of an early planetesimal. The gamma-ray and neutron spectrometer will help scientists determine the asteroid's chemical elements, while the multispectral imager will determine the mineralogy of any rocky material that may exist on Psyche's surface.

Journal Information:  L. T. Elkins‐Tanton et al, Observations, Meteorites, and Models: A Preflight Assessment of the Composition and Formation of (16) Psyche, Journal of Geophysical Research: Planets (2020). DOI: 10.1029/2019JE006296

NASA's Psyche mission: www.nasa.gov/psyche