Update 11/06/2018, 3:40PM: Comments included from Karen Meech and Olivier Hainaut.
‘Oumuamua, a blunt-shaped asteroid that's also the first object from another star system we've observed in our Solar System, may be a research probe sent from extraterrestrials in another star system, according to a research letter by two researchers from Harvard University's Smithsonian Center for Astrophysics. But the scientists who originally discovered it are already pushing back on these claims.
The research letter was published on arXiv.org on November 1, so keep in mind that the letter has not yet made it through the scientific peer-review process, and there is obviously a huge burden of proof on anyone claiming they’ve identified an alien artifact. According to researchers Shmuel Bialy and Abraham "Avi" Loeb, the asteroid accelerates in a peculiar manner, similar to the acceleration of a comet. But since various researchers have observed that the object has no comet tail or lines from the emission or absorption of gas, an explanation for its strange trajectory, they say, is that it was programmed by an intelligent extraterrestrial civilization.
“We discuss the possible origins of such an object including the possibility that it might be a lightsail of artificial origin. Our general results apply to any light probes designed for interstellar travel,” the letter states. “Interestingly, ‘Oumuamua’s entry velocity is found to be extremely close to the velocity of the Local Standard of Rest, in a kinematic region that is occupied by less than 1 to 500 stars.”
The proposition that 'Oumuamua is an alien probe also stem from the fact that it has a weird shape, as it's basically a long, thin, dusty red pancake. Collisions between objects in space create oddly-shaped asteroids all the time! But it’s more fun to say that 'Oumuamua is shaped like a spliff because it’s an alien probe.
Researchers who discovered ‘Oumuamua last year told Motherboard that the Harvard researchers have much more to prove.
Karen Meech, one of the researchers involved with the publication of ‘Oumuamua's discovery, told Motherboard in an email that 'Oumuamua's peculiar accelerations haven't been conclusively observed. She also said that the researchers mentioned the influence of solar radiation in the original paper, but Bialy and Loeb use it to justify an impossibly low density, 1,000 to 10,000 times smaller than that water.
"The Bialy and Loeb paper does not present good arguments for why solar radiation pressure would be a more plausible explanation," she said. "One needs to back extraordinary claims with extraordinary evidence."
Robert Weryk, another researchers involved with the discovery of ‘Oumuamua, said in an email to Motherboard that he does not think that the Harvard researchers made an “appropriate prediction” about the object’s origins.
“There is no reason to believe 'Oumuamua is anything but a natural object (a comet from another solar system) based on the observations that were obtained by the team I worked with,” Weryk said. “It is true though, that there really is a lot we do not know about interstellar comets, and it really will take us finding more of them to better understand them. This may take a while, but now that we know they exist, we are looking more closely at each new [near-Earth object] discovery we make.”
Robert Jedicke, another researcher involved with the original ‘Oumuamua's research, said in an email to Motherboard that he does not have an opinion yet regarding the Harvard research letter, but he pointed out that the letter has not been peer-reviewed yet. The assertions in this letter could shift once that process is complete.
The Harvard researchers point out that the acceleration of 'Oumuamua can be explained by pressure from Solar radiation, and that it could be powered by a light sail, a type of solar propulsion technology that, conveniently, one of those scientists is researching at Harvard.
“Considering an artificial origin, one possibility is that ‘Oumuamua is a lightsail, floating in interstellar space as a debris from an advanced technological equipment,” the letter reads. “Lightsails with similar dimensions have been designed and constructed by our own civilization, including the IKAROS project and the Starshot Initiative.”
Loeb, one of the authors of this research letter, is the chair of the Breakthrough Starshot Initiative at the Harvard University Astronomy Department. The express goal of the $100 million initiative is to demonstrate "proof of concept" for interstellar extraterrestrial drones. (IKAROS, meanwhile, is a solar power "sail" vehicle produced by the Japan Aerospace Exploration Agency, which has no affiliations with the authors.) I’m not saying that this research paper is one elaborate advertisement for solar sails, but the author’s affiliations definitely influenced his line of thinking.
Meech said in an email to Motherboard that the solar sail that the Harvard researchers mention is incompatible with the rotation of light curves, an orientation that makes it challenging to capture enough energy through light.
So ‘Oumuamua isn’t necessarily a message-in-a-bottle from extraterrestrials. It’s a cosmic time capsule of sorts, sent from indifferent violence in far-away galaxies. ‘Oumuamua is basically a crushed red chilli pepper tumbling over itself in a crazy orbit through the Solar System, and that’s incredible in and of itself.
Olivier Hainaut, one of the researchers involved with the original 'Oumaumau, told Motherboard in an email that it's best to just take eccentric theories with a grain of salt. “Google a little, and you will find some even more crazier interpretations," he said. "There is no limit on how weird and crazy one can get, and the crazier it is the more fun it is. Probably not related to reality, though."