In August 2024, the ATLAS telescope in South Africa discovered asteroid 2024 PT5, a ten-meter-wide space rock roughly the size of a school bus, according to Phys.org. Following its discovery, the small near-Earth object captured the attention of scientists worldwide due to its potential lunar origins.
Researchers conducted analyses of 2024 PT5. According to Spektrum der Wissenschaft, a study published in the Astrophysical Journal Letters presented evidence confirming its composition and movement, suggesting it is of local origin. Phys.org reported that the asteroid's orbit closely mirrors Earth's, which drew the interest of scientists and made it an ideal target for the Mission Accessible Near-Earth Object Survey (MANOS).
Data about 2024 PT5 were collected using the Lowell Discovery Telescope in Flagstaff, Arizona. Phys.org stated that a week after its discovery, researchers obtained reflectance spectra to determine its properties and composition. These observations aimed to ascertain whether 2024 PT5 was an artificial object, like space debris, or a naturally occurring asteroid.
In an official press release by NASA, Teddy Kareta, an astronomer at Lowell Observatory and the study's lead author, discussed the asteroid's composition. "The real evidence we found was when it turned out that it was rich in silicates. These are not silicates you find on asteroids, but in lunar rock samples," Kareta said, according to CNN. This silicate-rich composition aligns closely with Moon samples collected during past missions.
The asteroid's reflectance spectrum matches the characteristics of lunar rocks collected during the Luna 24, Apollo 14, and Apollo 17 missions.
Oscar Fuentes-Muñoz, co-author of the study, explained the significance of the asteroid's movement. "Space junk and space rocks move slightly differently in space. Space junk is usually relatively light and is pushed around by the pressure of sunlight. The fact that 2024 PT5 does not move in this way suggests that it is much denser than space junk," he said, according to Liverpool Echo.
The lack of space weathering on 2024 PT5 suggests it has not been in space for a prolonged period, probably only a few thousand years. Kareta explained that this absence of space erosion, which would have caused its spectrum to redden, indicates its recent escape from the lunar surface.
According to Universe Today, the discovery of 2024 PT5 doubled the number of known lunar-origin asteroids, joining 469219 Kamo'oalewa, identified in 2016.
Researchers suggest there may be between five and ten times more lunar-sourced asteroids in near-Earth orbits.
Carlos de la Fuente Marcos, a researcher at the Complutense University of Madrid, emphasized the importance of these findings. "The possibility that this belt is made of lunar debris is indeed an unexpected discovery," he said, according to CNN.
This article was written in collaboration with generative AI company Alchemiq