The surface of the massive, metal-rich asteroid Psyche—which orbits the Sun in the main asteroid belt between Mars and Jupiter—may harbor a large amount of low-iron pyroxene, according to a recent study published in The Astrophysical Journal Supplement Series.

The study, led by the Shanghai Astronomical Observatory of the Chinese Academy of Sciences, in collaboration with Macau University of Science and Technology, the University of Winnipeg, and other international institutions, advances our understanding of the surface composition of metallic asteroids and provides important scientific support for ongoing and future asteroid exploration missions.

Due to its unusually metal-rich nature, Psyche offers a unique opportunity to investigate the internal structure and evolutionary history of differentiated bodies in the early Solar System. It is also considered a potentially valuable target for future space resource utilization. It is estimated to contain enormous quantities of iron, nickel, and platinum-group metals, with reserves far exceeding known terrestrial ones.

To determine the asteroid surface compositions, scientists typically compare asteroid spectra with laboratory measurements of meteorites, minerals, and metallic materials. However, differences between laboratory conditions and the space environment make such comparisons extremely complicated.

In this study, the research team conducted a systematic spectral investigation of Psyche, mesosiderites, HED meteorites, and mixtures of metal and silicates in the visible and near-infrared wavelength band (0.3–2.5 μm).

The results showed that while the spectra of the 10:90 orthopyroxene-metal powder mixture were similar to that of Psyche, this does not necessarily mean that there is only a small amount (~10%) of pyroxene on Psyche's surface. Considering Psyche's density, there could be a large amount of low-iron pyroxene on its surface.

The researchers also found that certain types of mesosiderites match certain spectral aspects of Psyche. Given the similarities in certain spectral metrics and Fs content between HED meteorites and Vesta, the possibility that Vesta could be a mesosiderite parent body cannot be entirely ruled out. However, the higher metal content of mesosiderites makes them a more likely match for Psyche than HED meteorites.