Normally the people at SETI are using their equipment to scour the universe looking for radio signals that might hint we aren’t alone in the universe. SETI turned to a different task recently, and that task was to scan the interstellar object called Oumuamua and see if it had any radio emissions hinting that there might be technology aboard. Speculation suggested that the object might not be natural and could have come from an alien civilization.
SETI scientists say that they used the Allen Telescope Array (ATA) to observe Oumuamua when it was about 170 million miles away. That distance is slightly less than the diameter of the Earth’s orbit. The goal was to measure for artificial radio emissions that would indicate the object isn’t some random space debris tossed from its home star system by a gravitational slingshot interaction.
SETI says that despite “a quite sensitive search” it found no signals emanating from the rock. The scientists say that SETI observations don’t completely rule out that Oumuamua has a non-natural origin, the study also gathered important data in assessing the likely makeup of the object.
The scuttlebutt about non-natural origins for Oumuamua was mostly due to the shape of the object being similar to what author Arthur C. Clark wrote about an interstellar spacecraft in his book “Rendezvous with Rama.” Other than its looks being similar to a fictional starship, Oumuamua also lacked a coma which is unusual for asteroids and comets.
SETI observations were made between November 23 and December 5, 2017, using wide-band correlator of the ATA at frequencies between 1 and 10 GHz with a frequency resolution of 100 kHz. SETI says that no signals were found at a level that would be produced by an omnidirectional transmitter on the object with a power of 30-300 milliwatts.
While no radio signals were discovered on Oumuamua, the scientists say that their observations still have utility for the scientific community. The observations could shed light on the nature of any interstellar objects detected in the future or shed light on small but well-known objects in our solar system. The ESA announced that it had found stars that could be the home of Oumuamua in September.