What new methods can be used to detect alien technosignatures? This is what a recent study published in The Astrophysical Journal Letters hopes to address as a team of researchers from Pennsylvania State University (PSU) investigated how an extraterrestrial civilization could detect human signals. This study has the potential to help astronomers narrow the possibilities for searching for intelligent life beyond Earth and where we could look.
For the study, the researchers analyzed 20-year-old data logs from the NASA Deep Space Network (DSN), which is NASA’s international array of antennas that monitor active space missions, one of the most famous being the Voyager 1 and 2 spacecraft that have both left the solar system. The goal of the study was to ascertain the direction of the DSN signals and how an alien civilization could detect our signals.
In the end, the researchers found the majority of the DSN signals were sent along the ecliptic plane, or the orbits of the other planets in our solar system. Additionally, they found that an alien civilization had a 77 percent chance of detecting our signals within the last 20 years during an Earth-Mars conjunction, which is when both planets are on opposite sides of the Sun. The researchers note that searching for exoplanets via the transit method, when it passes in front of its host star, could be ideal exoplanets to search for signals. They also note DSN transmissions could be detected up to 23 light-years from Earth, and the search for alien signals could be narrowed to this distance from Earth.
“Humans are pretty early in our spacefaring journey, and as we reach further into our solar system, our transmissions to other planets will only increase,” said Dr. Jason Wright, who is a professor of astronomy and astrophysics in the Penn State Eberly College of Science and a co-author on the study. “Using our own deep space communications as a baseline, we quantified how future searchers for extraterrestrial intelligence could be improved by focusing on systems with particular orientations and planet alignments.”
What new insights into how aliens could detect human signals will researchers make in the coming years and decades? Only time will tell, and this is why we science!
As always, keep doing science & keep looking up!
Sources: The Astrophysical Journal Letters, EurekAlert!
Artist's illustration of a radio signal leaving Earth, getting partially blocked by Mars, and contiuing out into the comsos. (Credit: Zayna Sheikh)