Breaking: New search finds 'Oumuamua still isn’t an alien spaceship


Second sweep for radio signals turns up bupkis. Andrew Masterson reports.


An artist's impression of 'Oumuamua. Aliens not shown.

An artist's impression of 'Oumuamua. Aliens not shown.

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A “quite sensitive” search for artificial radio signals emanating from 'Oumuamua, the object that sped through the solar system in 2017, has failed to find any – but the researchers aren’t quite ready yet to give up on the possibility that the big flat rock was some sort of alien craft.

In a paper set to be published early next year in the journal Acta Astronomica, a team led by Gerry Harp from the SETI Institute in California, US, reports using the Allen Telescope Array – an instrument in part funded by Nathan Myhrvold and the late Paul Allen, both ex-Microsoft and dedicated to the search for ET – to observe 'Oumuamua and listen for radio transmissions.

“We were looking for a signal that would prove that this object incorporates some technology – that it was of artificial origin,” says Harp.

“We didn’t find any such emissions, despite a quite sensitive search. While our observations don’t conclusively rule out a non-natural origin for 'Oumuamua, they constitute important data in accessing its likely make-up.”

The SETI team is by no means the first to investigate whether the rock – which was first observed on 19 October 2017, about 33 million kilometres from the sun and already heading out of Dodge – was some form of alien craft.

In January 2018, a team led by astronomer Emilio Enriquez from the University of California, Berkeley, US, published a short paper detailing the search for narrow-band radio output from the object.

“Interstellar probes would likely be equipped with communication technology that could potentially be operating in the radio band,” it explained.

Maybe so, but 'Oumuamua, it turned out, wasn’t. Results, Enriquez and colleagues reported, were consistent with “previous observations during closer approach that the nature of the object is consistent with an asteroid-like composition”.

In the latest work, Harp and his collaborators looked for frequencies between one and 10 gigahertz.

The results matched those of Enriquez’s team. “We see no evidence of artificial transmitters,” it concludes.

Still, hope springs eternal. In a statement, the SETI Institute said the latest findings “may have utility in constraining the nature of any interstellar objects detected in the future, or even the small, well-known objects in our own solar system.

“It has been long-hypothesised that some of the latter could be interstellar probes, and radio observations offer a way to address this imaginative, but by no means impossible, idea.”


  1. https://www.sciencedirect.com/science/article/pii/S0094576518317168?via%3Dihub#!
  2. https://www.seti.org/ata
  3. https://arxiv.org/pdf/1801.02814.pdf
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