Few celestial bodies have aroused as much interest in the media as it has 3I/ATLAS in recent months. On July 1, the land impact warning system ATLAS (acronym in English for Last Alert System for Terrestrial Impact by Asteroids) detected an object moving through the solar system on an escape trajectory. Subsequent observations confirmed that it was our third interstellar visitorcoming from outside our solar system, after 1I/’Oumuamua and 2I/Borisov, although with a very different appearance from the previous ones.
This was already enough to make his observation interesting, but things were complicated by the speculations of some scientists about a non-natural origin, despite the fact that NASA indicated from the first moment that it was a cometalthough with unusual characteristics that have fueled the theory of the extraterrestrial ship.
Why it has been said that 3I/ATLAS could be an extraterrestrial spacecraft
Shortly after its discovery, and although it had not yet been able to be observed in detail, the theoretical physicist and Harvard astronomer Avi Loeb proposed in an article, together with researchers Adam Hibberd and Adam Crowlwhich could be an interstellar probe or ship sent by an intelligent species, perhaps with the goal of destroying Earth.
It was based on aspects such as its size, initially estimated at more than 20 kilometers, and a trajectory unusually aligned with the ecliptic plane of our solar system. The ecliptic is the imaginary plane that describes the Earth’s orbit around the Sun, so that of 3I/ATLAS is almost in the same plane as those of the planets.
In that first article, which he himself described on his blog as a ‘pedagogical’ exercise and ‘fun to explore, regardless of validity’Loeb proposed that the object could be hostile, in accordance with the so-called hypothesis of Dark Forest. This theory maintains that, since the resources of the universe are finite and we do not know the intentions of other civilizations, any life form could choose to preemptively attack another before it poses a threat. According to Loeb, the object could have precisely that purpose.
‘The solar eclipse of 3I/ATLAS seen from Earth during perihelion would allow it to realize a clandestine reverse Oberth solar maneuver, an optimal braking strategy for interstellar ships that want to be linked to the Sun. A possible optimal encounter with the Earth would occur at the end of November or beginning of December 2025,’ they wrote.
NASA had said from the beginning that 3I/ATLAS was a comet, but when the Hubble Space Telescope observed 3I/ATLAS, Loeb’s theory – who also speculated in 2017 that 1I/’Oumuamua was an extraterrestrial spacecraft – began to fail. Its size turned out to be much smaller than initially estimated: between 320 meters and 5.6 kilometers.
Why 3I/ATLAS is not an extraterrestrial spacecraft
A new study, still without peer review, has delved into the reasons why 3I/ATLAS is not an extraterrestrial spacecraft, because it is seen that common sense is not enough. In this new article, Eahsanul Haquescientist SETI and professor of Department of Geosciences, Universiti Teknologi Petronasexplains why it is a natural object.
‘Loeb and his colleagues found that the retrograde orbital plane of 3I/ATLAS is very close to the ecliptic, with only a 0.2% chance that this alignment is a coincidence,’ writes Haque, who adds that such an alignment, although uncommon, is not impossible for interstellar objects.
‘The galactic disk, where most stars are found, It is almost aligned with the ecliptic plane of the solar system. It is plausible that interstellar objects ejected from other systems follow similar trajectories,’ he says.
Haque points out that ‘the hyperbolic trajectory, with an eccentricity of about 6.1, and its high speed, about 58 km per second, are consistent with a gravitational ejection from a distant star systemjust as it was measured in 1I/’Oumuamua and 2I/Borisov. Additionally, the low probability of close encounters with Venus, Mars or Jupiter (about 0.005%) It is not exclusive to artificial objects. Natural comets can also show similar dynamics due to gravitational effects‘.
Loeb and his collaborators also pointed out the absence of certain chemical compounds as a possible indication of an artificial originbut Haque, when comparing its spectral slope with that of D-type asteroids and the interstellar comet 2I/Borisov, found that they are consistent with natural bodies.
In his analysis, Haque emphasizes that ‘Seligman et al. detected a slight variation in the light curve for about four days, indicating that the structure of the object is stable and there is no evidence of an acceleration greater than that caused by gravity‘. This differs from 1I/’Oumuamua, which did show a small non-gravitational acceleration attributed to degassing. ‘The fact that 3I/ATLAS does not show that acceleration is a solid argument against the idea of artificial propulsion‘.
What NASA says
Regarding these speculations, Tom StatlerNASA’s lead scientist for small bodies in the solar system, explained to The Guardian that 3I/ATLAS ‘looks like a comet. He does comet things. It looks very similar, in almost all aspects, to the comets we know. It has some interesting properties that differ slightly from comets in the solar system, but its behavior is that of a comet. All evidence overwhelmingly points to it being a natural body. It’s a comet‘.
Part of an exoplanet
Based on its trajectory, spectrum and cometary properties, Haque suggests that it could be ‘a lithified clastic fragment from an exoplanetary sedimentary basin’. Its trajectory indicates that it comes from thick disk of the Milky Waya region beyond our solar system in which there are stars much older than the Sun, with ages reaching 7 billion years.
This suggests that the object formed in a planetary system that had more than enough time to develop complex geological processesincluding the presence of liquid water capable of generating sedimentary basins. Furthermore, its size coincides with that of the large fragments that can detach from a planet after a high-speed impact.
Loeb, however, continues to do his thing and in a new article on his blog he states that there are 30/40% chance that the object is not of natural origin. ‘This low probability scenario includes the possibility of a black swan type event, similar to a Trojan Horsein which a technological object is passed off as a natural comet,’ he wrote, noting that his estimates could vary as more information is obtained.