Humans may not know any clever creatures outside of the earth, but if they exist, they may already know us. New research shows that radar systems at commercial and military airports have inadvertently declared our presence to listen.
Preliminary results from a study led by Ramiro Caisse Saide, a PhD candidate in astrophysics at the University of Manchester, suggest that electromagnetic signals leaked from global airlines such as John F. Kennedy International Airport in New York, and theoretically leaked from global airlines such as Heathrow Airport in New York and London. Military radar systems can also detect that due to their unique modes, the signals will be “apparently artificial, which can be seen by anyone watching interstellar distances with powerful radio telescopes,” Caisse Saide said in a statement.
“In fact, these military signals can appear a hundred times more from certain angles in space, depending on the observer’s location,” he added. “Our findings suggest that radar signals (inadvertently produced by any planet with advanced technology and complex aviation systems) can act as a universal sign of smart life.” However, it is important to note that signals take more years to reach any alien civilization 200 light years from Earth. Airports and military operations have signaled this power since the 1950s, so the maximum distance that aliens can detect is currently about 75 light-years in all directions.
When we live in a huge, ancient universe with billions of planets and moons, it shows that we are not the only intelligent life form among them. The desire for humans to connect with aliens dates back to more than 150 years. The first real attempt to communicate happened in 1974, when astronomers sent radio signals from the Arecibo Observatory in Puerto Rico and entered space. The signal, known as the Arecibo message, is composed of binary code that conveys basic chemicals about life, the structure of DNA, the position of the Earth in the solar system, and even the stick of humans. If any aliens received it, they did not respond.
This hasn’t stopped scientists from trying to find them. Those who seek alien intelligence (SETI) passively scan the space of electromagnetic signals, and natural phenomena cannot be explained. Others have adopted a more active approach by deliberately transmitting signals or messages to space (such as Arecibo messages). These efforts are called Meti (sending messages to alien intelligence) or CETI (communication with alien intelligence). Not everyone thinks it’s a good idea. Critics point out that telling aliens where we are could have catastrophic consequences if these creatures can harm us or our planet.
That was a terrible idea. Perhaps even more frightening is that the Earth is unknowingly yelling our existence and location to point to the alien civilization of any radar in the earmuff. To understand how noisy our planet is, Caisse Saide and his colleagues simulated how radar signals from airports flooded in time and space, and then analyzed their detectable from stars like Barnard and Au Microscopii. These stars are located approximately 6 and 32 light years away from the Sun, respectively.
They found that the airport radar system swept through the plane to inform the air traffic control sky and sent out a radio signal strong enough to allow aliens to detect it from up to 200 light-years using a telescope similar to West Virginia’s Green Bank radio telescope. That’s a big distance. The closest potentially habitable planet outside our solar system (Proxima centauri b) is 4 light years away and still requires state-of-the-art spacecraft from humanity to get there. The Earth’s military radar system has weaker signals, but is more concentrated and directional, forming a distinct artificial pattern similar to the lighthouse beam that swept the light.
However, it is important to note that the signal takes more years to reach any alien civilization 200 light years from Earth. Airports and military operations have signaled this power since the 1950s, so the maximum distance that aliens can detect is currently about 75 light-years in all directions. But the purpose of the study is that aliens located on the planet 200 light-years should be able to detect airport signals, but have not been able to stay for 125 years.
According to Caisse Saide, understanding how smart aliens might be aware of our existence can also help us find their search. He said that identifying and characterizing our own planet’s technological signatures or detectable technological signs can tell astronomers what to look for from other planets. Meanwhile, “we gained valuable insights into how to protect the radio spectrum of communications and design the radar systems of the future,” Michael Garrett, a professor of astrophysics at the University of Manchester, said in a statement. “Methods used to model and detect these weak signals can also be used in astronomy, planetary defense, and even monitoring the impact of human technology on our space environment.”
“In this way, our work supports the scientific pursuit of answering questions ‘Are we alone?’ said Caisse Saide, as well as the practical efforts to manage the impact of technology on our world and around the world.”
