#Scientists #traced #origins #potentially #dangerous #nearEarth #asteroid
(CNN) — Unusual asteroid traveling near Earth thought to be actually a piece of the moon, but how exactly it ended up traversing the solar system remains a mystery. Now, researchers say they’ve made a key connection in this cosmic puzzle.
The space rock, known as 2016 HO3, is a rare quasi-satellite, a type of near-Earth asteroid that orbits the Sun but stays close to our planet.
Astronomers first discovered it in 2016 thanks to the Pan-STARRS, or Panoramic Survey Telescope and Rapid Response System, telescope in Hawaii. Scientists call the asteroid Kamo’oalewa, a name derived from a Hawaiian creation song that alludes to an offspring traveling alone.
While most near-Earth asteroids originate in the main asteroid belt, between the orbits of Mars and Jupiter, new research has revealed that Kamo’oalewa likely came from the Giordano Bruno crater on the far side of the Moon. , or the side that faces the opposite side of Earth, according to a study published April 19 in the journal Nature Astronomy.
It’s the first time astronomers have tracked a potentially dangerous near-Earth asteroid to a lunar crater, said the study’s lead author, Yifei Jiao, a visiting scholar at the University of Arizona’s Lunar and Planetary Laboratory and a doctoral student at the University of Arizona. Tsinghua University in Beijing.
“This came as a surprise, and many were skeptical that it could come from the Moon,” study co-author Erik Asphaug, a professor at the University of Arizona lab, said in a statement. “For 50 years we have been studying rocks collected by astronauts on the surface of the Moon, as well as hundreds of small lunar meteorites that were randomly ejected by asteroid impacts from around the Moon and ended up on Earth. Kamo’oalewa is kind of the missing link that connects the two.” In addition to helping confirm Kamo’oalewa’s possible relationship with the Moon, the findings could ultimately lead to other revelations, such as how the ingredients for life reached Earth.
Once upon a time there was a crater
Kamo’oalewa, which measures between 46 and 58 meters (150 and 190 feet) in diameter, is about half the size of the London Eye. During its orbit, it comes within 14.5 million kilometers (9 million miles) of Earth, making it a potentially dangerous asteroid that astronomers are tracking and learning more about in case it ever gets too close to us. planet.
Previous research focused on the reflectivity of the asteroid, which, unlike typical near-Earth asteroids, is similar to lunar materials, for example in the space rock’s low orbital speed relative to Earth, a quality that suggests which comes from a relatively close area.
For the new study, astronomers used simulations to determine which of the moon’s thousands of craters could have been the asteroid’s point of origin.
The Giordano Bruno crater met all the criteria determined by the study’s impact simulations. Credit: NASA/GSFC/Arizona State University.
Based on the model, the team determined that the impactor that potentially created the asteroid would need to be at least 1 kilometer (0.6 mile) in diameter to dislodge such a massive fragment. When the object hit the Moon, it likely excavated Kamo’oalewa from beneath the lunar surface, sending the space rock flying to leave a crater more than 10 to nearly 20 kilometers (6 to 12 miles) in diameter.
These simulations also helped the team look for a relatively young crater, given that the asteroid is estimated to be only a few million years old, while the Moon is thought to be 4.5 billion years old.
These parameters helped researchers zero in on Giordano Bruno, a 22-kilometer-wide (14-mile) crater estimated to be 4 million years old, as the likely place where Kamo’oalewa began its journey.
The anatomy of an impact
The study’s simulations showed that Kamo’oalewa was carved into the lunar surface at several kilometers per second.
“You would think that the impact would pulverize and distribute the (lunar material) everywhere,” Asphaug said. “But there it is. So we turned the problem around and asked ourselves, ‘How can we make this happen?’”
Based on their models, the team believes the impact sent tens of hundreds of 10-meter (32.8-foot) fragments flying into space. However, Kamo’oalewa survived as a massive, singular fragment.
“While most of that debris would have impacted Earth as lunar meteorites over the course of less than a million years, a few lucky objects may survive in (solcentric) orbits as near-Earth asteroids, yet to be discovered or identified.” Jiao said.
Understanding how such a giant chunk of the Moon could remain intact enough to become an asteroid could help scientists study panspermia, that is, the idea that the elements for life may have been delivered to Earth as “organic hitchhikers” on space rocks such as asteroids, comets or other planets.
“While Kamo’oalewa comes from a lifeless planet, it demonstrates how rocks ejected from Mars could support life, at least initially,” Asphaug said.
The Kamo’oalewa specimen: a connecting piece of the puzzle
Studying impact craters on the Moon can also help scientists better understand the consequences of asteroid impacts should a space rock pose a threat to Earth in the future.
“Testing the new model of Kamo’oalewa’s origin from a young, specific lunar crater paves the way for real insights into the damage that asteroid impacts can cause to planetary bodies,” said study co-author Renu Malhotra. , professor of planetary sciences at the University of Arizona, in a statement.
The Chinese Tianwen-2 mission, set to launch in 2025, will visit Kamo’oalewa with the goal of collecting samples from the asteroid and eventually returning them to Earth.
“It will be different in important ways from any of the specimens we have so far: one of those connecting pieces that help you solve the puzzle,” Asphaug said.
The study of a sample excavated on the far side of the Moon could reveal information about a part of the Moon that was less studied and reveal data about the composition of its subsoil. Since the impact probably occurred a few million years ago (relatively young on astronomical time scales), the samples could also help scientists study how space radiation over time causes erosion on asteroids.
“The exciting thing is that when a space mission visits an asteroid and returns some samples, we have surprises and unexpected results that usually go beyond what we were anticipating,” said study co-author Dr. Patrick Michel, an astrophysicist and director of research from the French National Center for Scientific Research. “Therefore, whatever Tianwen-2 brings, it will be an extraordinary new source of information, like all asteroid missions so far.”
For a long time, astronomers thought it was impossible for meteorites to come from the Moon until lunar meteorites were found on Earth, said Noah Petro, NASA project scientist for both the Lunar Reconnaissance Orbiter and Artemis III. Petro did not participate in the study.
The hope is that future samples can confirm Kamo’oalewa’s lunar origin.
“Going there and finding out is absolutely a way to continue now,” Petro said. “It’s a great reminder that we live in a very interesting solar system and that we live in a very interesting corner of the solar system with our Moon. There is no other place, no other planet in our solar system with a Moon like ours. And things like this are great reminders of how special the Earth-Moon system is.”
