The study indicates that if an alien civilization is trying to detect signals from Earth, the highest chance is during an alignment between Earth and Mars, when transmissions to spacecraft and rovers on Mars are made at high intensity.
A new study from Penn State University and NASA's Jet Propulsion Laboratory (JPL) has examined what our deep space transmissions look like to extraterrestrial eyes. The researchers analyzed decades of radio communications from the Deep Space Network (DSN), NASA's array of antennas that enables two-way communication with spacecraft, and identified where and when these powerful signals tend to "leak" out into space.
The study suggests that if an alien civilization is trying to detect signals from Earth, it is most likely to do so during an alignment between Earth and Mars. Pin-Chen Fan, a graduate student in astronomy and astrophysics at Penn State and the lead researcher on the paper, explained that most of the transmissions from Earth are intended for spacecraft and probes around Mars. Since Mars does not block all of the signal, an intelligent being far away from us, who is in a straight line with Earth and Mars, could pick up the remnants of the transmission.
Over the past 20 years, it has been found that in such a case there is a 77% chance of being in the transmission path – compared to a tiny chance in a random location. When it comes to alignment with other planets in the solar system, the chance drops to 12%.
Technological signals and the connection to SETI
The article was published inAstrophysical Journal Letters , on August 21, 2025, and presented at the Penn State SETI Conference. The researchers emphasize that our analysis of the direction and frequency of the transmissions provides new insights for searches for technosignatures – signs of technology from intelligent extraterrestrial civilizations.
Joseph Lazio of JPL, one of the authors of the paper, explained that the DSN sends humanity's strongest and most persistent radio signals into space - for example, to the probe New Horizons that has already left the solar system, and to the James Webb Space Telescope. The transmission patterns revealed show where aliens might pick us up – and where we should look back.
The study focused on deep space transmissions and did not include satellites in low Earth orbit, as these transmissions are too weak to be detected from a distance.
The findings showed that most of the signals were sent to spacecraft near Mars, and to instruments in space at Lagrange points between the Earth and the Sun.
Additionally, the researchers note that most of the transmissions are centered around the plane of the system—just as if the solar system were a flat plate, our signals would travel along it. They estimate that telescopes of our caliber would be able to detect an average transmission from a distance of up to 23 light years. This means that it’s worth focusing on planets outside the solar system that face us.
Pan noted that with the launch of the Nancy Grace Roman Space Telescope, hundreds of thousands of new planets are expected to be discovered – which will greatly expand the search area.
Broad implications for S
The conclusions are not limited to radio transmissions. DSN patterns could also be used to search for laser transmissions, although these tend to leak much less. NASA is already exploring interstellar laser-based communication systems.
Professor Jason Wright of Penn State, one of the authors of the paper and director of the university's SETI Center, concluded:
"We are still in the early stages of our journey as a spacefaring culture. As we launch more distant missions, our transmissions will only increase. By understanding our communication patterns, we can refine our search for intelligent life – and direct it to the right places and times."
Source and details
The study: Detecting Extraterrestrial Civilizations that Employ an Earth-level Deep Space Network
By Pin-Chen Fan, Jason Wright, Joseph Lazio. Published inThe Astrophysical Journal Letters, , August 21, 2025.
DOI: 10.3847/2041-8213/adf6b0
The research was supported by NASA's Exoplanet Research Program and Penn State's SETI Center. The calculations were performed on the supercomputers of the Penn State Institute for Data Science.
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One response
If the transmission is directed towards the plane of the solar system, why not point receiving antennas towards the planes of other star systems, assuming that they (aliens?) are directing radio communication between planets of the same star system, as we are, towards Mars.