Scientists are preparing for the launch of the Mission to Psyche by working to understand the asteroid as best we can from here on Earth first. To that end, a research team used the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile to map Psyche’s thermal emissions. They managed to do this at a resolution of 30 kilometers per pixel, which is impressive, and they created a map of the asteroid’s surface. 

The resulting thermal map shows that Psyche has higher thermal inertia than a typical asteroid, and that could mean it is dense or more conductive than expected. Additionally, Psyche only radiates about 60 percent of the expected heat based on that thermal map, meaning Psyche is no less than 30 percent metal. Based on an analysis of the polarization, or how the light is scattered off the surface of the asteroid, Psyche is covered in rocks that have metallic grains. It’s not a smooth, solid surface. 

So, no, Psyche is not a roundish core of a broken protoplanet, but it is heavily metallic and more likely a very primitive asteroid that formed closer to the Sun than its present position. We’ll have to wait for that mission to Psyche to get there and take a sample before we’ll know for certain what the asteroid really looks like and what it’s made of. The paper on this map was published in The Planetary Science Journal with lead author Katherine de Kleer.

More Information

Caltech press release

“The Surface of (16) Psyche from Thermal Emission and Polarization Mapping,” Katherine de Kleer, Saverio Cambioni, and Michael Shepard, 2021 August 5, The Planetary Science Journal