By Dean Murray
A near-Earth asteroid has been traced to a huge crater on the Moon.
Space rock 2016 HO3, also known as Kamo’oalewa, is thought to have been blasted off the lunar surface, leaving the 14-mile-wide Giordano Bruno crater on the moon’s far side.
A new study suggests the asteroid is unlike other relatively close asteroids, which are thought to hail from the main asteroid belt between the orbits of Mars and Jupiter.
The find also marks the first time scientists have traced an asteroid to its exact place of origin.
The study published in the journal Nature Astronomy says Kamo’oalewa, which has a similar orbit around the Sun as Earth, has been hurtling through space for several million years.
Selected as the target of China’s Tianwen-2 mission, Kamo’oalewa measures between 150 and 190 feet in diameter, making about half the size of the “London Eye” ferris wheel.
According to lead study author Yifei Jiao, a visting scholar at the University of Arizona Lunar and Planetary Laboratory, the report is the first account of a potentially hazardous near-Earth asteroid that has been linked to a specific crater on the moon.
To shed light on the mystery, the research team used impact and dynamical modeling. According to the simulations, it would have required an impactor of at least 1 kilometer (0.6 mile) in diameter to launch a large fragment like Kamo’oalewa beyond the moon’s gravitational pull.
While the lunar surface is riddled with thousands of craters from impacts spanning the moon’s 4.5 billion year-history, only Giordano Bruno with its 14-mile diameter and estimated 4 million years of age fits the bill in terms of size and age, making it the most probable source of Kamo’oalewa’s origin.
Erik Asphaug, co-author and Lunar and Planetary Laboratory professor, says: “This was a surprise, and many were skeptical that it could come from the moon.
“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 ejected randomly by asteroid impacts from all over the moon that ended up on Earth. Kamo’oalewa is kind of a missing link that connects the two.”
According to Asphaug, the model provides more than just an explanation for the origin story of one particular asteroid. How massive rocks can be ejected from the surface of a planet and survive intact can be informative for fundamental questions, such as the origin of life in the universe.
One such theory, known as panspermia, suggests that life – or its ingredients – could have been brought to planetary bodies from other sources across space, in the form of “organic hitchhikers” coming along for the ride, Asphaug explained.
“While Kamo’oalewa comes from a lifeless planet, it demonstrates how rocks ejected from Mars could carry life – at least in principle,” he said.
