The deepest, broadest search for alien technologies ever conducted has found no trace of intelligent life.

The survey, which used the Murchison Widefield Array (MWA) of radio telescopes in outback Western Australia, scanned a patch of sky around the constellation of Vela. That area of the night sky has at least 10 million stars, and was studied for 17 hours using low frequencies.

Does this mean there is no intelligent life out there?

No. What it means it that we’ve looked under one more rock—albeit a bigger one than we’ve looked under before—and found nothing. The task now is to keep looking.

This is SETI—the search for extraterrestrial intelligence—and it’s most likely an ultra long-term project.

“Even though this was a really big study, the amount of space we looked at was the equivalent of trying to find something in the Earth’s oceans but only searching a volume of water equivalent to a large backyard swimming pool,” said Professor Steven Tingay from the Curtin University node of the International Centre for Radio Astronomy Research (ICRAR), one of the two authors of the MWA SETI study, whose results are published this week.

The telescope was searching for powerful radio emissions at frequencies similar to FM radio. It’s thought that evidence of such emissions could be “technosignatures”—signatures of advanced alien technologies similar to, or perhaps more advanced than, human technology on Earth.

The scientists have now examined 75 known exoplanets at low frequencies, but found nothing.

What is radio astronomy?

Radio astronomy is the detection of radio waves emitted by celestial objects. Some of the radio signals collected by the MWR will have traveled billions of light years before reaching Earth.

What is the MWA?

The Murchison Widefield Array (MWA) is a low-frequency radio array in Western Australia. It consists of 4,096 antennas in 256 grids across several kilometres within the Murchison Radio-astronomy Observatory (MRO). 

It’s been scanning the southern hemisphere’s night skies since 2013.

“The MWA is a unique telescope, with an extraordinarily wide field-of-view that allows us to observe millions of stars simultaneously,” said Dr. Chenoa Tremblay, an astronomer at CSIRO. “Although there is a long way to go in the search for extraterrestrial intelligence, telescopes such as the MWA will continue to push the limits—we have to keep looking.”

However, now being constructed at MRO is the SKA, which will be of supreme interest to intelligent life-hunters.

What is the SKA?

Spread over a square kilometre—one million square metres—the Square Kilometre Array (SKA) will be the world’s largest radio telescope. It’s a $2.1 billion observatory with sites in Western Australia and South Africa, which both see the same area of the southern hemisphere’s night sky.

The Australian section of the SKA will be built at the same location but its thousands of dishes and up to a million low-frequency antennas will make it 50 times more sensitive than the MWA.

“Due to the increased sensitivity, the SKA … will be capable of detecting Earth-like radio signals from relatively nearby planetary systems,” said Tingay. “We’ll be able to survey billions of star systems, seeking technosignatures in an astronomical ocean of other worlds.”

Is the search for intelligent life beyond Earth like looking for a needle in a haystack? Yes, absolutely, which is why it’s often overlooked in favor of research with more chance of a short-term reward.

However, there are encouraging signs. As well as noting that SETI surveys are making rapid progress, the authors of the MWA SETI survey conclude that large-scale SETI surveys can be performed in the background while telescopes are being used for more immediate astrophysical purposes.

Whisper it, but we might find aliens by accident.

Wishing you clear skies and wide eyes.