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This near-Earth object was likely ejected into space after an impact thousands of years ago. Now it can contribute new insights into asteroid and lunar science.

Last year, NASA-funded telescopes captured the world's attention when they discovered that the near-Earth object 2024 PT5 hovered near Earth but never orbited it for more than a few months. The asteroid is about 33 feet (10 meters) wide and poses no danger to Earth, but its orbit around the sun is very close to our planet, suggesting it may have originated nearby.

As described in a study published Jan. 14 in the Astrophysical Journal Letters, researchers have gathered further evidence that 2024 PT5 has a local origin: It appears to be composed of rocks that broke off from the lunar surface and merged in a single Ejected into space after a big impact.

"We generally thought the asteroid might have come from the moon, but that was confirmed when we found it was rich in silicate minerals - not the kind seen on asteroids, but the kind found in lunar rocks "It doesn't look like it has been in space very long, probably only a few thousand years or so," said astronomer Teddy Kareta of the Lowell Observatory in Arizona, who led the study. The lack of space weathering does not cause its spectrum to become reddish. "

The asteroid was first discovered on August 7, 2024, by the NASA-funded Asteroid Terrestrial Impact Final Alert System (ATLAS) telescope at the University of Hawaii in Sutherland, South Africa. Carretta's team then used observations from the Lowell Discovery Telescope and NASA's Infrared Telescope Facility (IRTF) at Mauna Kea Observatory in Hawaii to show that the spectrum of sunlight reflected from the asteroid's surface is consistent with that of any known asteroid. No matching type; instead, the reflected light is closer to coming from the moon's rocks.

The second clue comes from observing how objects move. In addition to asteroids, space-age debris, such as old rockets from historical launches, can also be found in Earth-like orbits.

The difference in their orbits is related to each type's response to solar radiation pressure, which comes from the momentum of photons (quantum particles of light from the sun) that exert tiny forces when they strike solid objects in space. Over time, the momentum exchange of many photons can nudge an object slightly, causing it to speed up or slow down. While man-made objects, like hollow rocket boosters, move in the wind like empty tin cans, natural objects, like asteroids, are much less affected.

To rule out the possibility that 2024 PT5 was space junk, scientists at NASA's Center for Near-Earth Object Studies (CNEOS), which is managed by the agency's Jet Propulsion Laboratory in Southern California, analyzed its motion. Their precise calculations of an object's motion under gravity ultimately allowed them to look for additional motion caused by solar radiation pressure. In this case, we found that the object's impact was too small to be man-made, proving that 2024 PT5 is most likely of natural origin.

"Space debris and space rocks move slightly differently through space," said study co-author Oscar Fuentes-Muñoz, a postdoctoral researcher at NASA's Jet Propulsion Laboratory who worked with CNEOS teamwork. "Man-made debris is usually relatively light and gets pushed around under the pressure of sunlight. The fact that 2024 PT5 did not move in this way suggests that it is much denser than space debris."

The discovery of 2024 PT5 doubles the number of known asteroids thought to have originated from the Moon. Asteroid 469219 Kamo'oalewa, discovered in 2016, has an Earth-like orbit around the sun, suggesting it could also have been ejected from the lunar surface after a large impact. As telescopes become more sensitive to smaller asteroids, more potential lunar boulders will be discovered, creating exciting opportunities not only for scientists studying rare asteroid populations, but also for scientists studying the moon. People are excited about the opportunity.

If a lunar asteroid can be directly linked to a specific impact crater on the moon, then studying it could provide insight into the cratering processes on the pockmarked lunar surface. In addition, material from deep within the lunar surface - in the form of asteroids close to Earth - may be available for future scientists to study.

"This is the story of the moon as told by asteroid scientists," Carretta said. "This is a rare situation where we go out to study an asteroid and stumble into new territory in terms of questions we can ask 2024 PT5."

The ATLAS, IRTF, and CNEOS projects are funded by NASA's Planetary Defense Program, which is managed by the Planetary Defense Coordination Office at NASA Headquarters in Washington.

For more information about asteroids and comets, visit:

Ian J. O'Neill
Jet Propulsion Laboratory, Pasadena, California
818-354-2649
ian.j.oneill@jpl.nasa.gov

Karen Fox/Molly Wasser
NASA Headquarters, Washington
202-358-1600
karen.c.fox@nasa.gov / molly.l.wasser@nasa.gov

Kevin Schindler
Lowell Observatory Public Information Officer
928-607-1387
kevin@lowell.edu

2025-007