For the past 50 years, scientists have been searching for signs of intelligent life in the universe by looking for specific electromagnetic signals referred to as technosignatures.
Despite decades of research and the growing belief that the ingredients for life are widespread throughout the universe, this high-stakes quest has yet to yield any evidence of intelligent beings beyond Earth.
The conventional method of searching for alien life, known as the Search for Extraterrestrial Intelligence (SETI), has typically involved using large single-dish telescopes to scan the skies for signals at frequencies above 1 GHz. However, scientists are now exploring a new avenue of research by focusing on the underexplored radio window below 1 GHz.
This shift in focus is based on the understanding that any extraterrestrial civilization attempting to communicate with us would likely transmit signals that are distinguishable from natural background noise.
SETI has viewed radio frequencies as a promising avenue for a long time, given their usage in human telecommunications and radar. The presumption is that extra-terrestrial civilizations might also use radio waves to communicate or signal their presence. As a result, radio astronomy has been a crucial part of SETI since the 1960s, with various studies looking for narrowband radio emissions that could be intentional transmissions or unintentional leaks from sources outside the Earth.
Astronomers are constantly searching for signals from the universe to better understand the cosmos. However, due to challenges such as ionospheric interference, the low-frequency signals in the 110-190 MHz range have seen limited exploration. To overcome this, astronomers are now expanding their search to include this frequency range. This initiative represents a significant departure from previous efforts, which have predominantly focused on higher frequencies.
Professor Evan Keane from Trinity College Dublin, in cooperation with the Breakthrough Listen project and Onsala Space Observatory, has conducted a study that highlights the potential of multisite simultaneous observations to eliminate human-made signals and focus on possible technosignatures from distant star systems.
The team surveyed 1.6 million star systems using the Irish and Swedish LOFAR stations, targeting the systems identified by the Gaia and TESS space missions. Although they have not yet identified a clear signal from intelligent extraterrestrial life, the SETI community’s commitment to exploring new segments of the radio spectrum and the upcoming improvements to the LOFAR array demonstrate a renewed passion for this field.