What could aliens pick up from the radio leak from Earth? How would Earth look to an alien civilization light years away from us?
In a joint study by a group of scientists from the University of Mauritius and the University of Manchester, they used crowdsourced data to model the radio signals emanating from cell phone towers. The goal was to speculate what such a distant civilization could potentially pick up from a variety of nearby stars, including Barnard's Star, which is only six light years from Earth.
Ramiro Seida, an intern at the SETI Institute's Hat Creek Radio Observatory and graduate student at the University of Mauritius, has developed models that represent the strength of the radio frequencies these aliens will pick up as the Earth rotates and the towers rise and set.
Saida believes that unless an alien civilization is far more advanced than we are, it would have a hard time detecting the current levels of radio leakage from Earth's cell phone antennas. But, the team argues that it is likely that some technical cultures have much more sensitive reception systems than ours, and the ability to detect our cellular systems will increase significantly as we move to much more powerful transmission systems.
Saida is also excited by the fact that his simulations show that the country's cellular radio signature includes a significant contribution from developing countries, including Africa. Says the head of the team Professor Mike Garrett: "The results show that Africa managed to bypass the development stage of wired telephony and moved directly to the digital age."
Garrett is satisfied with the results: "I heard many colleagues who claimed that Haaretz's radio signature has decreased in recent years - a claim that I have always disputed. It is true that today there are fewer powerful TV and radio transmitters, but cellular communication systems around the world are very common. Each system by itself has a relatively low radio power, but the combined spectrum of these billions of devices is significant."
Dr. Nelini Hirlal-Isor, Seida's supervisor in Mauritius, thinks he may be right: "Every day we add knowledge about the characteristics of exoplanets through space missions like Kepler and TESS, with additional insights from JWST. I believe that there is a chance that there are advanced civilizations out there in space, and some of them might be able to notice the man-made radio leak coming from Earth."
The team is eager to expand the research to other factors that contribute to the country's radio leak signature. The next step will be to include powerful civilian and military radar, new digital broadcast systems, Wi-Fi networks, individual cell phones and the many sets of satellites now being launched into low orbit around the country, such as Elon Musk's Starlink system.
According to Garrett, "According to current estimates, we will have more than a hundred thousand satellites in low orbit around the country and further by the end of the decade. The earth is already unusually bright in the radio part of the spectrum. If the trend continues, any advanced culture with the appropriate technology will be able to discover us easily."
"This study is an excellent example of how a detailed analysis of the properties of human technology (the "anthropogenic technosphere") can be used to develop innovative and exciting strategies for the discovery of extraterrestrial technologies," said project scientist Dr. Waal Fara from the Allen Telescope Array. "We look forward to using the unique instrumentation capabilities and timing flexibility of the Allen telescope array, along with our growing knowledge of nearby exoplanet systems, and conducting new studies based on these strategies."
More of the topic in Hayadan: