An observatory in Chile has taken measurements of the surface temperature of asteroids with the highest resolution ever obtained from Earth.
Scientists have carefully studied the 1 mm waves emitted by the asteroid Psyche and, based on this data, obtained a temperature map of the object, from which you can learn more about the properties of its surface.
Psyche contains a large amount of iron and nickel, and without any admixtures of water or water-containing minerals, which is quite a rare occurrence. A small amount of pyroxenes was also found. Therefore, scientists suggest that Psyche is a metal core or a fragment of a larger body, a protoasteroid, which has been destroyed.
The early solar system was a cruel place: planets merged and then collided, changed orbits. We think that fragments of their cores, mantle and crust can be found today in the form of asteroids. For example Psyche gives us the only real opportunity to directly study the nuclei of planet-like objects.
Catherine de Kleer, lead article author and assistant professor at California Institute of Technology
Studying such small and distant objects as Psyche, which is now 179.5 to 329 million km from Earth, is a serious problem, so NASA plans to send a probe to the asteroid to collect data about it up close.
However, before the launch of the mission, observations of Psyche continue: in the new work, the authors studied data from 66 radio telescopes and, based on them, compiled a map of thermal radiation from the entire surface of Psyche.
It was possible to make measurements with such accuracy thanks to the ALMA radio telescope complex, which observed the Psyche at millimeter wavelengths that are longer than infrared. The authors used longer wavelengths and this allowed them to combine data from all telescopes.
The study confirmed that Psyche’s thermal inertia is higher than that of a typical asteroid. This means that it has an unusually dense or conductive surface. When de Claer and the team analyzed the data, they also found that Psyche’s thermal radiation is only 60% of that of a typical surface with such thermal inertia. This suggests that the surface of Psyche is at least 30% metal.
Analyzing the polarization of the radiation helped the researchers to roughly determine what shape this metal takes: the usually smooth solid surface of the asteroid emits polarized light. However, the light from Psyche was scattered, probably its surface is covered with metal bumps.
The methods described in this study open up new possibilities for detailed study of the features of asteroids. The authors plan to apply similar methods to other large objects in the asteroid belt.