An artistic representation of the oumuamua of an interstellar visitor showing comet-like outgassing behavior.
Credit: NASA / ESA
If the first interstellar object ever discovered in our solar system is actually an alien spaceship, it works in stealth mode.
A search for radio signals from & # 39; Oumuamua, the mysterious visitor From afar, zoomed through the inner solar system last fall, a new study appeared.
"We were looking for a signal that would prove that this object contains technology that is of artificial origin," said the study Lead author Gerry Harp from the SETI (Institute for the Exploration of Extraterrestrial Intelligence) in Mountain View, California. said in a statement. [̵
"We have found no such emissions despite a fairly sensitive search," added Harp. "While our observations do not clearly rule out a non-natural origin for Oumuamua, they are important data for accessing the probable composition."
Harp and his colleagues used the Allen Telescope Array (ATA) of the SETI Institute, a system of 42 radio dishes in Northern California, to listen for possible 'Oumuamua' signals from November 23 to December 5 last year. At that time, the bizarre cigar-shaped object was about 275 million kilometers from Earth – nearly twice as far as our planet was from the Sun.
The team heard pings at a frequency between 1 and 10 gigahertz with a resolution of 100 kilohertz. The observation campaign was able to record signals from an omnidirectional transmitter with a power between 30 and 300 milliwatts, the researchers said.
"In all cases, these limits of perceived performance are relatively low – comparable to that of mobile phones or citizen band radios," wrote the SETI Institute in the same statement.
Harp and his team were not the only group that had overheard Oumuamua last fall. The $ 100 million project Breakthrough Listen has also tried with the Robert C. Byrd Green Bank Telescope in West Virginia. This search did not yield anything.
SETI scientists are so interested in & # 39; oumuamua because of the origin and uncanny nature of the object. & # 39; Oumuamua is a strangely tumbling, needle-shaped body that is probably six times longer than it is wide. And during its cruise through the Earth's neighborhood late last year, it showed acceleration without gravity – a movement that is not attributable to the tugs of the sun, planets or other objects.
The leading explanation is that & # 39; Oumuamua is an alien comet and The Strange Movement was the result of outgassing. (As comets approach the sun and heat up, jets often erupt from their icy surfaces, such jets can act as small thrusters, driving bodies in this and that direction.)
However, some scientists have suggested that & #; 39; Oumuamua could be a kind of spaceship, perhaps a reconnaissance probe that was to investigate the neck of our cosmic forest. Harvard astronomers Shmuel Bialy and Avi Loeb have recently outlined such a case, claiming that Oumuamua may be a "sailing ship" swept along by the starlight.
Unfortunately, such speculations about & # 39; oumuamua can prevail forever. The object was not within reach of our strongest telescopes long ago, so we'll probably never see it again.
The new study will be published in the February 2019 issue of the journal Acta Astronautica.
Mike Wall's book on finding an extraterrestrial life "Out There" (Grand Central Publishing, 2018, illustrated by Karl Tate) has now been published. Follow him on Twitter @michaeldwall . Follow us @Spacedotcom or Facebook. Originally published on Space.com.