The sensational claim was made by Amir Siraj, a colleague of Harvard Professor of Physics Avi Loeb, after the pair authored a report entitled Ruling out the nitrogen model for Oumuamua, which was recently accepted for publication in New Astronomy magazine. Oumuamua was spotted by Robert Weryk on October 19, 2017, using a telescope at the Haleakala Observatory in Hawaii.
Ever since, the debate over what Oumuamua was has raged within the scientific community, especially given its peculiar, flattened shape, somewhat like a pancake.
Prof Loeb courted enormous controversy for his suggestion that it may have been some sort of alien probe powered by a piece of technology he theorised to be a solar sail.
Many of his peers are highly sceptical, and two studies published in March suggested it could be a large chunk of nitrogen ice from a Pluto-like exoplanet millions of years ago – a so-called “nitrogen iceberg”.
But Mr Siraj, who as director of Interstellar Object Studies at Harvard’s Galileo Project is dedicated to the systematic scientific search for evidence of extraterrestrial technological artefacts said the latest study, which he co-authored with Prof Loeb, appears to disprove the possibility.
He told Express.co.uk: “The nitrogen conclusion has received a lot of attention.
“However, we show that the nitrogen model requires a mass of heavy elements that exceed the total quantity locked in stars – the absolute theoretical maximum – which means that there is the model is ruled out.”
Neither he nor Prof Loeb were drawing any firm conclusions, Mr Siraj stressed.
He explained: “We don’t know what Oumuamua was. We just know that it’s not nitrogen, since the mass budget would be untenable.”
Oumuamua’s appearance was tantalisingly brief.
When was first observed, it was roughly 21 million miles from the Earth and already heading away from the Sun.
Between 300 and 3,000 feet long, and 115 and 548 feet thick, and red in colour, scientists are positive it originates outside our solar system – but other than that, there is little consensus.
As such, Mr Siraj said it would be foolish to rule anything out – or in.
He added: “There’s no way to know what Oumuamua was since it is already gone.
“All plausible possibilities, including the artificial origin one, must be kept in mind during observations of future interstellar objects like Oumuamua.”
In the meantime, the scientific community remains fixated on an event which is unique in the lifetime of our civilisation, Mr Siraj pointed out, namely the first time an extrasolar object had been tracked, albeit briefly.
He continued: “All of the existing theories regarding Oumuamua’s provenance invoke never-before-seen astrophysical phenomena, including an ultra-porous aggregate a hundred times less dense than air, a planet fragment that was tidally disrupted, exotic icebergs made of almost pure hydrogen or pure nitrogen, or a piece of artificial technological equipment.
“The up-close study of an object like Oumuamua from outside of the solar system, whether natural or artificial in origin, would reveal unprecedented insights about planet formation and life in the universe, transforming humanity’s understanding of our place on the cosmic stage.”
Speaking on the sidelines of New Scientist Live, where he was a guest speaker, in 2019, Prof Loeb told Express.co.uk he thinks of himself as a “space archaeologist”.
He said: “There are many cultures that existed in the past that we don’t have direct access to but we can find their relics and I think we should think about space the same way.
“It is much more likely that things existed and are not around anymore due to either self-inflicted wounds or from natural disasters – you can have an asteroid impact or a flare from a hostile sun, something which happened with the planet which basically eliminated life.
“But until that point, there was a culture that created infrastructure that we can look for and we can look for megastructures that are left on the planet or around the planet, or a tiny swarm of satellites that were artificially made.
“We can find things from the surface that indicate that there was a war or you can find technological equipment, artificial lights that exist even though the civilisation is dead by now, you can find industrial pollution.”
He added: “My colleagues unfortunately are not thinking about these possibilities when they explore planets elsewhere.
“They are extremely conservative and they focus on at most primitive life.
“I don’t see why we should put blinders on our telescopes. We should be open-minded to the possibility that we are not alone.”