by Earth’s “quasi-moon” likely moved away from the actual moon recently in the solar system’s history, a new study suggests.
Kamo’oalewa, a 131 to 328-foot-wide (40 to 100 meters) near-Earth object (NEO), was freed by an asteroid impact between 1 million and 10 million years ago, a smashup that created 13.7-13.7- the moon. mile wide (22 kilometers) Giordano Bruno crater, according to the research.
The Pan-STARRS 1 asteroid survey telescope on Haleakalā, Hawaii, Kamo’oalewa, or “469219 Kamoʻoalewa” as it is officially named, was discovered in 2016 as part of NASA’s planetary defense effort to find space rocks that could to be hit on our planet to find out. .
Kamo’oalewa, meaning “oscillating celestial object” in Hawaiian, The sun was later found to be orbiting in sync with Earth and is spinning incredibly fast for an asteroid. These strange characteristics have allowed scientists to investigate the origin of the curved moon. In 2021, research revealed that the composition of Kamo’oalewa is similar to rocks recovered from the moon, suggesting its lunar origin. The question was, Where exactly on the moon did it come from?
Related: Earth’s ‘quasi-moon’ asteroid companion could be a lunar remnant
“Our main findings are that Kamo’oaelewa came from the moon, and not from the asteroid belt, contrary to the majority of asteroids belonging to the NEO population,” Patrick Michel, team member and senior researcher at the Center National de la Recherche Scientifique (CNRS) , the French state research agency, said Space.com.
“Like detectives, we used all the information known about this Kamo’oalewa and the surface of the moon to find a case for the origin of this object, starting from the impact that created the Giordano Bruno crater,” a Michel said.
Recreating a ‘cosmic crime scene’ on the moon
The team connected Kamo’oalewa to the Giordano Bruno crater by working like crime scene investigators. They used a computer model to simulate the type of impact a space rock like this crescent would have produced.
That meant factoring in things like the size and velocity of the resulting ejecta distribution and their dynamic evolution. This reconstruction showed that some ejecta would eventually enter a 1:1 resonance orbit with Earth, having the same dynamical properties as Kamo’oalewa.
“Our results tell us that Kamo’oalewa is very likely to be a fragment from the lunar surface that we have a direct relationship with a known crater if our scenario is correct,” said Michel.
“Usually, the best we can do is to determine the source region in the NEO asteroid belt, knowing their current orbit. These estimates usually cover a very broad region, such as the inner asteroid belt or outside,” he said. added. “Here, we identified a body and a very specific location where this object comes from, which is very exciting.”
Michel explained that Kamo’oalewa’s orbit is not stable, leading the team to link it to a crater that is not too old, perhaps between one and 10 million years old.
“Then we also had to keep the crater from being too big, so that an intact fragment the size of Kamo’oaelewa can be produced,” he continued. “The best candidate then was Giordano Bruno, who fits both constraints.”
The team’s impact modeling also gave them an idea of the size of the space missile that would have created the nearly 14-mile-wide lunar crater and its near-lunar ejecta. They estimated that the asteroid that hit the moon must have been about 1 mile (1.6 kilometers) wide to carve the Giordano Bruno crater and free Kamo’oalewa.
If an asteroid of that size were to hit Earth, it would release about the same amount of energy as detonating one million megaton bomb.
Related: How we could deflect killer asteroids away from Earth
The findings also have ramifications for our understanding of the NEO population around Earth, suggesting that a larger than expected proportion of these bodies may have been created by impacts on the moon or other solar system bodies .
“Although most NEOs come from the main asteroid belt between Mars and Jupiter, a small proportion can come from the moon or other places,” said Michel. “When there is an unusual object and it looks like it may have a lunar origin, we now know that we can check whether the orbit of the suspected object can be a fragment from the moon and perhaps the identify the crater from which it comes, closing the loop. .”
Michel added that the discovery that the Giordano Bruno crater is likely connected to the NEO Kamo’oalewa is a stark reminder that even in this quieter era of the solar system’s 4.6 billion year history, massive space rock impacts occur.
This underscores the importance of planetary defense projects such as NASA’s recent Double Asteroid Redirect Test (DART), which studied the effectiveness of redirecting an asteroid on a collision course with Earth.
“Impacts occur in the inner solar system, but while traces are destroyed on Earth, they are not destroyed on the moon. Therefore, the history of impacts in the Earth’s environment over the last 4 billion years is recorded in our natural satellite,” said Michel . . “This is why some of us are very involved in planetary protection, NASA’s DART mission which performed the first asteroid deflection test and the European Space Agency’s Hera mission, for which I serve as principal investigator, which will measure the outcome of DART impacts i. minor.”
RELATED STORIES:
— Asteroid Apophis will zip past Earth in 2029 – could a space rock collision hit us?
– NASA’s DART mission reshaped its asteroid target. This is how
— NASA’s Lucy asteroid spacecraft reports surface ages of 1st asteroid target
Michel admits that the team’s results are only temporary. So, although they have provided a strong connection between Kamo’oalewa and the moon, it will take further investigation of the asteroid to confirm this connection.
“China’s Tiawen-2 mission will offer the next most exciting study of Kamo’oalewa which should be launched in 2025 to sample the surface of the asteroid and bring the samples back to Earth for laboratory analysis,” he said. “This is a very challenging mission, as no one has visited such a small object that rotates on its own in 28 minutes before.
“The analysis of the samples will tell us, for the first time, what it is [are] physical and thermodynamic state of a fragment of this size removed from the lunar surface by an impact, which we cannot determine in our impact model.”
The team’s research was published Friday (April 19) in the journal Nature Astronomy.
