may not be what scientists expected

New research from the University of Arizona found that the target asteroid NASAPsyche’s mission may not be as metallic or intense as previously expected.

The widely studied metallic asteroid 16 Psyche has long been believed to be the exposed iron core of a small planet that did not form during the early days of the solar system. But new research led by the University of Arizona suggests that the asteroid may not be as metallic or dense as previously thought, and suggests a very different origin story.

Scientists are interested in 16 Psyche because if its supposed origins are correct, it would provide an opportunity to study an exposed planetary core up close. NASA is scheduled to launch its Psyche mission in 2022 and reach the asteroid in 2026.

David Cantello, a student at the University of Arizona, is the lead author of a new research paper published in Planetary Science Magazine Suggesting that 16 Psyche is 82.5% metal, 7% low iron pyroxene, and 10.5% carbonaceous chondrite which likely came from collisions with other asteroids. Cantello and his collaborators estimate that the apparent density of 16 Psyche, also known as porosity, which refers to the amount of empty space inside your body, is around 35%.

NASA Illustration of Psychological Spaceship

Illustration, created in March 2021, of NASA’s Psyche spacecraft, which aims to launch into the main asteroid belt in August 2022 to investigate the asteroid Psyche. Image Credit: NASA / JPL-Caltech / ASU

These estimates differ from previous analyzes of the composition of 16 Psyche that led the researchers to estimate that it could contain up to 95% of the mineral and be more dense.

“This decrease in mineral content and bulk density is interesting because it shows that 16 breaths are more modified than previously thought,” Cantello said.

Rather than being the intact exposed core of a primitive planet, it may actually be more like a pile of debris, similar to another carefully studied asteroid: Bennu. UArizona leads NASA’s science mission team Osiris Rex The mission, which recovered a sample from Bennu’s surface and is now returning to Earth.

“A puff like a rubble heap would be very unexpected, but our data continues to show low-density estimates despite its high mineral content,” Cantello said.

Asteroid 16 Psyche is the size of Massachusetts and scientists estimate that it contains about 1% of all material in the asteroid belt. First discovered by an Italian astronomer in 1852, it was the 16th asteroid in history.

“Having a lower mineral content than previously thought means that the asteroid may have collided with asteroids containing the more common carbonaceous chondrites, which deposited a surface layer that we are observing,” Cantello said. This was also observed on the asteroid Vesta by NASA’s Dawn spacecraft.

Asteroid 16 Psyche has been valued at $ 10,000 trillion (that’s $ 10,000 followed by 15 additional zeros), but the new results may slightly underestimate the value of the iron-rich asteroid.

“This is the first document to put some specific limitations on its surface content. Previous estimates were a good start, but this improves these numbers a bit more, ”Cantelo said.

Another well-studied asteroid, Bennu, contains a lot of carbonaceous chondrite and has a porosity of more than 50%, a classic feature of a debris pile.

This high porosity is common for relatively small, low-mass objects like Bennu, which is as large as the Empire State Building, because the weak gravitational field prevents the body’s boulders and boulders from clumping together too tightly. But for a 16-breath body to be so porous, that’s unexpected.

“The opportunity to study an exposed core of a small planet is extremely rare, so they are sending a spacecraft mission there, but our work shows that 16 psyches are more interesting than expected,” Cantelo said.

Previous estimates of the composition of 16 Psyche were made by analyzing sunlight reflected off its surface. Match the light pattern with other metal objects. Instead, Cantelo and his collaborators recreated 16 Psyche rays, or loose rocky surface material, mixing different materials in the lab and analyzing light patterns until they matched telescope observations of the asteroid. Only a few labs in the world practice this technique, including the Lunar and Planetary Laboratory in Arizona and the Johns Hopkins Applied Physics Laboratory in Maryland, where Cantelo worked while in high school.

“I’ve always been interested in space,” said Cantillo, who is also president of the UArizona Astronomical Club. “I knew astronomy studies would be heavy on computers and observations, but I like to do more practical work, so I wanted to connect my studies with geology in some way. I specialize in geology and I specialize in planetary sciences and mathematics ”. “

“David’s paper is an example of the cutting-edge research work done by our undergraduate students,” said study co-author Vishnu Reddy, an associate professor of planetary sciences who runs the lab where Cantillo works. “It’s also a good example of a collaborative effort between college students, graduate students, postdoctoral fellows, and my lab staff.”

The researchers also believe that the carbonaceous material on the surface of 16 Psyche is rich in water, so they will then work to combine data from ground-based telescopes and spacecraft missions to other asteroids to help determine the amount of water present.

Reference: “Restriction of the regolith formation of the psychic asteroid (16) by near infrared visible spectroscopy in the laboratory” by David C. Cantillo, Vishnu Reddy, Benjamin NL Sharkey, Neil A. Pearson, Juan A. Sánchez, Matthew RM Aizawa, Theodore Caretta, Tanner S. Campbell, and Umm Shubra, May 12, 2021, Available here. Planetary Science Magazine.
DOI: 10.3847 / PSJ / abf63b

Funding: NASA Near-Earth Object Observation Program

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