A group of astronomers has begun the first-ever search for signals from alien technology from a galaxy beyond Earth, using a large radio antenna array in rural Australia.
The effort was initiated by the SETI Institute, the Berkeley SETI Research Center, and the International Center for Radio Astronomy Research. The collaboration conducted observations using the Murchison Widefield Array, a radio observatory in Western Australia with 4,096 antennas. The array's antennas resemble a cloud of metal spiders arranged in a grid pattern. While not as spectacular as some of the larger radio observatory antennas, the array is well suited to deep space radio observations.
The team's study, now published on the preprint server arXiv, took advantage of the array's wide field of view to scan 2,800 galaxies in one observation. This sets this study apart from previous studies that have focused primarily on radio sources within the Milky Way. Stars in the Milky Way are 40,000 to 100,000 light-years away, while nearby galaxies are 2 to 30 million light-years away – a huge difference in scale.
“One of the main challenges in searching for signs of extraterrestrial intelligence is the speed at which the sky can be surveyed,” the team wrote in their paper. “Even with the wide viewing angles offered by aperture arrays like MWA, dedicated experiments running on shared instruments are limited in how much of the sky they can cover and how frequently they can cover the same celestial objects.”
According to the SETI Institute, for an extraterrestrial civilization from another galaxy to send a message detectable on Earth, it would need to be technologically advanced enough to use its host star or stars as a power source. This classification is based on the Kardashev scale of advancement for intelligent life, which defines three basic classes of civilizations and their level of advancement according to the energy they have available:
The Western Australian array has been used in the past to search for extraterrestrial intelligence (SETI). In 2020, it was searched extensively for alien signatures, without success. It may seem like a no-brainer, but recent searches have not yielded any technosignatures, i.e. signs of extraterrestrial life operating with their own technology. But if you don't film it, you're 100% screwed!
The researchers noted that current and planned telescopes are speeding up the search. Specifically, the Very Large Interferometer and the MeerKAT telescope will both help search for alien signals at radio wavelengths. Let's hope the aliens are familiar with standard radio communication protocols like “Got it” and “Over.” Otherwise, we'll be stuck with Airplane-style routines when dealing with extraterrestrials, which is bad enough for humans.
