In a paper posted on Cornell University’s arXiv e-print archive, and due to be published in the Astrophysical Journal Letters on Nov 12, joint authors Avi Loeb and Shmuel Bialy have said that the bizarre-looking cigar-shaped interstellar object that passed through our solar system last year could well be an interstellar spacecraft.
Loeb, who is the chairman of Harvard’s astronomy department, and Bialy, a postdoctoral fellow at the Harvard-Smithsonian Center for Astrophysics, have rejected the possibility of Oumuamua being an asteroid or a comet because it’s too small to qualify as either of the two.
“Known Solar System objects, like asteroids and comets have mass-to-area ratios orders of magnitude larger than our estimate for ‘Oumuamua,” they wrote.
One of the possible scenarios they presented in regards to the mysterious object’s origin is that Oumuamua is nothing but “a lightsail, floating in interstellar space as a debris from an advanced technological equipment.”
“Lightsails with similar dimensions have been designed and constructed by our own civilization, including the IKAROS project and the Starshot Initiative2,” they said.
Another scenario, which Loeb and Bialy think is more exotic, is that Oumuamua might well be an alien spacecraft on an Earth mission.
“Alternatively, a more exotic scenario is that ‘Oumuamua may be a fully operational probe sent intentionally to Earth vicinity by an alien civilization,” said the Harvard boys.
However, as it is a little too late in the day to image the baffling object with existing telescopes or send chemical rockets after it, the best way forward in so far as deciphering Oumuamua’s likely origin and mechanical properties is concerned is to search for similar objects in the future, suggested Loeb and Bialy.
“In addition to the vast unbound population, thousands of interstellar ‘Oumuamua-like space-debris are expected to be trapped at any given time in the Solar System through gravitational interaction with Jupiter and the Sun,” they wrote.
It all started last year when a team of astronomers at the Pan-STARRS 1 observatory on Haleakala, Hawaii, spotted an unidentified elongated object during a routine search of the skies for near-Earth objects on behalf of NASA.
Being among the first to spot this freak asteroid from outside our solar system they aptly named it Oumuamua, which in Hawaiian means a first messenger from far away.
Further inspection of follow-up images from an ESA (European Space Agency) telescope on Tenerife in the Canary Islands revealed to IfA graduate Marco Micheli that there was, indeed, something unusual about the object.
Combining the data from both centers made it evident that it was indeed an interstellar intruder – an alien asteroid from beyond our solar system.
“This object came from outside our solar system,” Weryk said at the time.
“Davide Farnocchia, a scientist at NASA’s Center for Near-Earth Object Studies (CNEOS) at the agency’s Jet Propulsion Laboratory in Pasadena, California, noted that the orbit of the object was “most extreme,” the likes of which he had never seen before.
“It is going extremely fast and on such a trajectory that we can say with confidence that this object is on its way out of the solar system and not coming back,” he concluded.
“Oumuamua is dense, comprised of rock and possibly metals, has no water or ice, and that its surface was reddened due to the effects of irradiation from cosmic rays over hundreds of millions of years,” NASA said about the discovery.
The kind of interest and curiosity that Oumuamua raised among the scientific community is evident from the fact that dozens of observatories with high-powered telescopes, worldwide, scrambled to track this mysterious blast from the interstellar past in order to learn as much about it as possible, before it left our solar system.
Again, in September this year, an international team of astronomers, led by Coryn Bailer-Jones from the Max Planck Institute for Astronomy in Heidelberg, Germany, were able to identify four dwarf stars, any one of which could likely be the home of the mysterious piece of interstellar rock.
What went in favor of the four dwarfs is the fact that they are believed to have come within a couple of light-years of Oumuamua, somewhere between one and seven million years ago.
One of the dwarf stars known as HIP 3757 appears to be somewhat reddish in color, while another is similar to our sun and is referred to as HD 292249; however, not much is known about the other two.
“The one that came closest to ‘Oumuamua, at least about one million years ago, is the reddish dwarf star HIP 3757,” said a statement released by the Max Planck Institute.
“It approached within about 1.96 light-years. Given the uncertainties unaccounted for in this reconstruction, that is close enough for ‘Oumuamua to have originated from its planetary system (if the star has one),” the statement said.
“However, the comparatively large relative speed (around 25 km/s [16 miles/s]) makes it less probable for this to be ‘Oumuamua’s home,” it said.
“As for the other named dwarf, the Max Planck statement said: “The next candidate, HD 292249, is similar to our sun, was a little bit less close to the object’s trajectory 3.8 million years ago, but with a smaller relative speed of 10 km/s [6 miles/s].”
Bailer-Jones and his team’s findings were based on data collected by the European Space Agency’s Gaia probe, which included a whopping seven million stars, as well as 220,000 stars mentioned in the astronomical literature.
Coming back to the Harvard research, many experts in the field are skeptical about the alien spacecraft theory, something that Loeb and Bialy are also not too sure of, calling it an “exotic scenario.”
One such expert is Seth Shostak, a senior astronomer at the SETI Institute in Mountain View, California, who refuses to buy the alien angle to Oumuamua.
“It’s certainly ingenious to show that an object the size of Oumuamua might be sent by aliens to another star system with nothing but a solar sail for power,” Shostak told NBC News in an email.
“But one should not blindly accept this clever hypothesis when there is also a mundane (and a priori more likely) explanation for Oumuamua — namely that it’s a comet or asteroid from afar,” he said.