Near-Earth objects (NEOs), which closely follow our planet in strange horseshoe-shaped paths, can sometimes come close enough for hours, days, or months to become mini-moons, although they do not complete a full revolution around our planet.
An example of such objects temporarily captured by Earth during its flyby is 2022 NX1. It was a short-lived mini-moon in 1981 and 2022, it will be so again in 2051 and could even collide from 2075, but without serious consequences due to its small size.
Today, two astronomers from the Complutense University of Madrid (UCM), brothers Carlos and Raúl de la Fuente Marcos, have verified that a recently discovered asteroid called 2024 PT5 will also become a mini-moon this same year: from September 29 to November 25. The details have just been published in the magazine AAS Research Noteswhere it is also stated that he will return in 2055.
The small object, estimated to be about 10 meters in size, was discovered on August 7 in South Africa by the Asteroid Last Land Impact Alert System (ATLAS), a set of robotic astronomy instruments that detect smaller near-Earth objects shortly before their possible impact with Earth.
A week after the discovery, 2024 PT5 was already registered in a circular of the Minor Planet Center, the body of the National Astronomical Union responsible for designating minor bodies in the solar system. Immediately, the two Spanish astronomers received the alert, made the calculations and verified that at the end of this month it will become a mini-moon.
“Mini-moon episodes occur when an object, approaching our planet at a very low astronomical speed (of the order of 3,500 km/h), acquires a negative geocentric energy value or a geocentric eccentricity less than 1,” Carlos tells SINC.
“This means,” he explains, “that its gravitational energy relative to the Earth takes on a negative mathematical value as it approaches and thus temporarily becomes its satellite, even if it does not make a complete revolution like the Moon, but only one arc of its orbit. Furthermore, it is generally found less than 4.5 million kilometers from the Earth.
Two types of minimoons
The astronomer explains that two types of mini-moons are considered. On the one hand, those that remain linked to our planet for one or more years, which allows them to describe one or more orbits around it. Only two examples of this class are known: 2006 RH120 and 2020 CD3.
On the other hand, there are mini-moons that only spend weeks or months with us, so they do not orbit the Earth. These are more common and studies have been presented on 1991 VG (although it exceeded the limit of 4.5 million kilometers from Earth during the almost two months when its geocentric eccentricity was less than 1), 2022 NX1 and now 2024 PT5, for example, but they are increasingly unpublished.
Good time to send missions
In addition to their scientific interest, mini-moons could also offer economic benefits, as some could contain valuable mineral resources that could be exploited by future space mining companies. In this context, a good time to approach them would be the period during which they are close to Earth.
“Even during the briefest mini-moon episodes, it is still possible to travel to the asteroid with moderate fuel consumption, compared to an object with a geocentric eccentricity greater than one,” Carlos explains.
“Therefore,” he adds, “on paper, it would be possible to design a low-cost space mission to reach one of these mini-moons in a short-duration capture episode, say a few months, to collect samples and bring them back to Earth.”
What is the origin of PT5 2024?
Regarding the origin of 2024 PT5, the article points out that it is unlikely to be artificial, since its short-term dynamic evolution is very similar to that of 2022 NX1, a celestial body that has been confirmed to be natural. “It is not an object made by human beings, it is not space debris,” Raúl emphasizes.
The study indicates that its orbital elements match those of the Arjuna asteroids (named after the famous Hindu hero), a population of small near-Earth objects from a secondary asteroid belt whose orbit is very similar to that of the Earth-Moon system.
The asteroid’s previous orbital evolution suggests that “it may be a piece ejected during an (asteroidal) impact with the Moon.”
Although the authors cannot currently confirm the possibility that 2024 PT5 is a fragment of our own satellite, director of the Center for Near-Earth Object Studies (CNEOS) at NASA’s Jet Propulsion Laboratory, Paul Chodas, said: New York Times that the asteroid’s previous orbital evolution suggests that “it may be a piece ejected from an (asteroidal) impact with the Moon.”
Observation with the Gran Telescopio Canarias
To confirm this hypothesis and obtain more data, the Fuente Marcos brothers and researchers from the Institute of Astrophysics of the Canary Islands (IAC) observed the small object this month with the Gran Telescopio Canarias. Their primary objective was to obtain the visible light reflectance spectrum of the asteroid.
Currently, the IAC-UCM collaboration is carefully analyzing the data, but their current impression is that 2024 PT5 could likely be a fragment of the Moon itself. In the coming months, they will publish the final results.
Source: SINC
Rights: Creative Commons.
