Can ET detect us?

Newswise — A team of researchers from Mauritius and Manchester University has simulated what an alien civilization, located light years away, would see when looking at the Earth. Using crowd-sourced data, they predicted radio leakage from mobile towers to create models displaying the radio power that these civilizations would receive as the Earth rotates and the towers rise and set. The team believes that unless the alien civilization is much more advanced than ours, they would have difficulty detecting the current levels of mobile tower radio leakage from Earth. However, they suggest that more technically advanced civilizations could have much more sensitive receiving systems, and the detectability of our mobile systems will increase substantially as we move to much more powerful broadband systems. Mountain View, CA, Manchester, UK, and Mauritius were involved in this study.

Ramiro Saide's simulations also revealed that the mobile radio signature of the Earth includes a significant contribution from developing countries in Africa. This fact excited Saide, and according to team leader Professor Mike Garrett from the University of Manchester's Jodrell Bank Centre for Astrophysics, it highlights Africa's success in skipping the landline stage of development and transitioning directly to the digital age. Garrett also disagrees with the notion that the Earth has become increasingly radio quiet, stating that although there may be fewer powerful TV and radio transmitters today, the proliferation of mobile communication systems worldwide is significant. The integrated spectrum of billions of mobile devices represents a substantial amount of radio power, even though each system only emits relatively low radio powers individually.

Dr. Nalini Heeralall-Issur, Saide’s supervisor in Mauritius, shares his excitement and believes that Saide's simulation might be accurate. She notes that with every new space mission, like Kepler, TESS, and the upcoming James Webb Space Telescope (JWST), we are learning more about exoplanets and their characteristics. With this new knowledge, Heeralall-Issur thinks that there is a good chance that there are advanced civilizations out there capable of observing the human-made radio leakage coming from Earth.

The team plans to expand their research to include other sources of radio leakage from Earth. This will include more powerful civilian and military radars, new digital broadcast systems, Wi-Fi networks, individual mobile devices, and satellite constellations such as Elon Musk’s Starlink system. Professor Garrett suggests that the Earth will become even brighter in the radio part of the spectrum with the launch of over 100,000 satellites in low Earth orbit and beyond by the end of the decade. He believes that if this trend continues, any advanced civilization with the right technology will be able to detect our planet easily.

Dr. Wael Farah, the Allen Telescope Array Project Scientist, praised the research and highlighted the potential for using the array's instrumentation and knowledge of nearby exoplanet systems to conduct new searches based on the team's strategies. He described the work as an excellent example of how analyzing human technology can lead to innovative methods for detecting extraterrestrial technologies.

The paper has been accepted by MNRAS: https://academic.oup.com/mnras/article/522/2/2393/7028804

The paper is also available on the arXiv:  https://arxiv.org/abs/2304.13779

Saide’s M.Phil research has been funded by the Development in Africa with Radio Astronomy (DARA) Project: www.dara-project.org

About the SETI Institute
Founded in 1984, the SETI Institute is a non-profit, multi-disciplinary research and education organization whose mission is to lead humanity’s quest to understand the origins and prevalence of life and intelligence in the Universe and to share that knowledge with the world. Its research encompasses the physical and biological sciences and leverages expertise in data analytics, machine learning and advanced signal detection technologies. The SETI Institute is a distinguished research partner for industry, academia and government agencies, including NASA and NSF.