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In 2022, NASA will launch a spacecraft into the asteroid Psyche (16 Psyche), one of the largest in the asteroid belt, and the only known asteroid that is composed almost entirely of metals such as iron and nickel.
Now, scientists have taken a new look at Psyche using the Hubble Space Telescope, making the first ultraviolet observations of this asteroid since the 1980s. Hubble has provided new insights into Psyche’s surface and composition, as well as possible activity. that takes place on the surface of Psyche.
“We were able to identify for the first time in any asteroid what we think are iron oxide ultraviolet absorption bands,” said planetary scientist Dr. Tracy Becker of the Southwest Research Institute, lead author of a new paper describing the observations. “This is an indication that oxidation is occurring on the asteroid, which could be the result of the solar wind hitting the surface.”
Scientists have long speculated that this metallic asteroid could be the remaining surviving core of a protoplanet, where perhaps a violent collision with a planetesimal stripped the outer rocky layers of Psyche, leaving behind only the dense, metallic interior. This theory has been supported by estimates of the apparent density, spectra, and surface properties of Psyche’s radar, all of which show that it is an object unlike any other in the asteroid belt. Furthermore, this 16 Psyche composition is strikingly similar to that of Earth’s metallic core.
“We have seen meteorites that are mostly metal, but Psyche could be unique in that it could be an asteroid entirely made of iron and nickel,” Becker said in a press release. “The Earth has a metal core, a mantle and a crust. It is possible that while a Psyche protoplanet was forming, it was struck by another object in our solar system and lost its mantle and crust. “
Becker and his team used Hubble to make high-resolution UV observations of Psyche taken in 2017 with the observatory’s Space Telescope Imaging Spectrograph (STIS). They observed the asteroid at two specific points in its rotation to see both sides of Psyche fully at ultraviolet (UV) wavelengths.
They observed some small spectral differences between the sides, perhaps suggesting an unusual feature in the northern hemisphere, but overall, the spectra they observed showed that iron is the main feature of the surface.
“We found no significant spectral variations with rotation, although the asteroid’s equatorial region may have a higher overall reflectance than the northern hemisphere,” the team wrote in their paper. Psyche also seemed increasingly reflective at deeper ultraviolet wavelengths.
“This is something we need to study further,” Becker said. “This could indicate that it has been exposed in space for so long. This type of ultraviolet glow is often attributed to space weathering. “
The team also compared Psyche’s spectrum with meteorite samples from a specific database, but found no strong matches.
The observations were made in preparation for the Psyche mission, which will travel to the asteroid as part of an effort to understand the origin of the planetary cores. The mission will launch in 2022 and reach Psyche in 2026. Since the asteroid Psyche is so far from Earth, approximately 280,0000,000 km, we do not have a clear understanding or clear images of this object. Metallic asteroids are relatively rare in the solar system and scientists believe that Psyche could offer a unique opportunity to see the interior of a planet.
“What makes Psyche and the other asteroids so interesting is that they are considered the building blocks of the solar system,” Becker said. “Understanding what really constitutes a planet and potentially seeing the inside of a planet is fascinating. Once we get to Psyche, we’ll really understand if that’s the case, even if it doesn’t turn out how we hope. Every time there is a surprise, it is always exciting. ”
The study was published in The Planetary Science Journal and presented at the American Astronomical Society’s Division of Planetary Sciences virtual meeting last week.
Main Image Title: Artist’s impression of the huge asteroid 16 Psyche. Credit: Maxar / ASU / P. Rubin / NASA / JPL-Caltech.
