The much-studied metallic asteroid 16 Psyche has long been considered the exposed iron core of a small planet that did not form in 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 history of formation.
Scientists are interested in 16 psyche, because if its supposed origins are correct, it would offer the opportunity to study an exposed planetary core up close. NASA is scheduled to start 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. has been published Journal of Planetary Science This suggests that 16 Psyche is 82.5% metal, 7% iron-poor pyroxene, and 10.5% carbonaceous chondrite, which likely came from collisions with other asteroids. Cantillo and his coworkers estimate that the volume density of 16 psyche – also known as porosity, which refers to the amount of empty space in his body – is about 35%.
These estimates differ from previous analyzes of the composition of 16 Psyche, which led 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 psyches are more modified than previously thought,” said Cantelo.
Rather than being the intact exposed core of an early planet, it might actually be more like a heap of debris, similar to another carefully studied asteroid – Bennu. UArizona leads the scientific mission team for NASA’s OSIRIS-REx mission that recovered a sample from the surface of Bennu, which is now returning to Earth.
“A pile of rubble breath would be very unexpected, but our data continues to show low density estimates despite the high mineral content,” said Cantello.
Asteroid 16 Psyche is the size of Massachusetts, and scientists estimate that it contains about 1% of the total material in the asteroid belt. It was first discovered by an Italian astronomer in 1852 and was the 16th asteroid ever.
“A lower mineral content than previously thought means the asteroid may have collided with asteroids that contain the more common carbonaceous chondrites that have deposited a surface layer that we are observing,” said Cantelo. This was also observed on the asteroid Vesta by NASA’s Dawn spacecraft.
Asteroid 16 Psyche was valued at $ 10,000 quadrillion ($ 10,000 followed by 15 additional zeros), but the new findings could easily underestimate the value of the iron-rich asteroid.
“This is the first paper to have some specific surface area restrictions,” said Cantelo. “Earlier estimates were a good start, but that improves those numbers a bit.”
Another well-studied asteroid, Bennu, is rich in carbonaceous chondrite and has a porosity of over 50%, a classic feature of a pile of rubble.
This high porosity is common with relatively small, low-mass objects like Bennu – which is the size of the Empire State Building – because a weak gravitational field prevents the object’s boulders and boulders from clumping together too tightly. But for a 16 breath body that’s so porous, that’s unexpected.
“The opportunity to examine an exposed core from a small planet is extremely rare, which is why they are sending a spaceship mission there, but our work shows that 16 psyches are more interesting than expected,” said Cantelo.
Previous estimates of the composition of 16 psyche were made by analyzing the sunlight reflected from its surface. Adjust the light pattern to match other metal objects. Instead, Cantello and colleagues recreated 16 psyche regolith – or soft, rocky surface material – by mixing different materials in the laboratory and analyzing the light patterns until they matched the observations made by the asteroid’s telescope. Few laboratories in the world practice this technique, including the UArizona Lunar and Planetary Laboratory and the Johns Hopkins Laboratory of Applied Physics in Maryland, where Cantelo worked during his school days.
“I’ve always had an interest in space,” said Cantillo, who is also the president of the UArizona Astronomical Club. “I knew that studying astronomy would be a drag on computers and observations, but I like doing more hands-on work, so I wanted to somehow combine my studies with geology. I’m majoring in geology and planetary science and math. ”
David’s essay is an example of his cutting-edge research StudentsStudy co-author Vishnu Reddy, associate professor of planetary science who runs the laboratory where Cantillo works, said. It’s also a good example of collaboration between undergraduate, graduate students, postdoctoral researchers, and staff in my laboratory. “
The researchers also believe that the carbonaceous material on the surface of 16 Psyche is water-rich. Therefore, they will then work on combining data from ground-based telescopes and spacecraft missions to other asteroids to determine how much water there is.
David C. Cantillo et al, Restriction of regolith formation on the asteroid (16) breath by visible near-infrared spectroscopy in the laboratory, Journal of Planetary Science (2021). DOI: 10.3847 / PSJ / abf63b
University of Arizona
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