The asteroid Psyche (or 16 Psyche) is the destination of one of NASA’s next missions for the year 2026. Now, a more detailed examination of the asteroid’s millimeter wavelength emissions and carried out by experts from the University from Arizona (USA), has revealed the first temperature map of the object , providing a new perspective on its surface properties. And it seems that it was not what scientists expected.
The asteroid – which was originally discovered in 1852 – might not be as metallic or dense as we thought and suggests a completely different origin than the one initially proposed by scientists, who thought it was a core fragment of protoplanets that broke apart when it formed. the solar system.
At over 200 kilometers in diameter, this asteroid, the largest of the M-type asteroids , is found orbiting the Sun in the asteroid belt, a donut-shaped region of space between Mars and Jupiter that contains more of a million rocky objects.
New temperature map
The researchers took advantage of the Atacama Large Millimeter / submillimeter Array (ALMA) in Chile to obtain such data. The set of 66 radio telescopes allowed the team to map the thermal emissions of the entire surface of Psyche at a resolution of 30 kilometers. In the data set, each pixel measures about 30 x 30 kilometers and, when combined, they generate an image of the asteroid made up of about 50 pixels.
The new research has determined that it may not be as metallic or as dense as scientists thought , as the data say it has 82.5% metal, 7% pyroxene with low iron content (rock-forming minerals) and 10.5% carbonaceous chondrite (stony).
The study confirmed that Psyche’s thermal inertia is high compared to that of a typical asteroid, indicating that it has an unusually dense or conductive surface. Its apparent density, or porosity, is around 35%. These figures therefore indicate Psyche as considerably less metallic and more porous than what previous studies had concluded (which presented it as 95% metal and significantly less dense).
“The findings are a step toward solving the mystery of the origin of this unusual object, which some have thought to be a part of the nucleus of an unfortunate protoplanet ,” according to the study authors.
It is possible that Psyche is like other famous asteroids like Bennu and Ryugu. Bennu is a pile of debris that was visited by NASA’s Osiris-Rex mission, which took a sample to bring it back to Earth and Ryugu was visited by the Japanese Hayabusa2 mission and recently returned samples to Earth for further study. .
“Our data continues to show low-density estimates despite its high metallic content,” said David Cantillo, leader of the paper that publishes the Planetary Science Journal.
Can we still consider it a large metallic asteroid?
Reference: David C. Cantillo et al, Constraining the Regolith Composition of Asteroid (16) Psyche via Laboratory Visible Near-infrared Spectroscopy, The Planetary Science Journal (2021). DOI: 10.3847 / PSJ / abf63b
