NASA Deep Space Network guides astronomers in the search for alien intelligence

For decades, the search for alien intelligence has revolved around the question: if someone out there is listening, how could they hear us? A new study combining data from Penn State and NASA’s Jet Propulsion Laboratory suggests that our own deep space transmissions may provide a roadmap — both for alien observers and for our efforts to find them.

Researchers dug into 20 years of NASA Deep Space Network (DSN) transmission logs to analyze how often, and in which directions, our strongest signals travel. The findings highlight that human communication patterns are far from random. Instead, they tend to align with specific planetary movements, offering clues for where astronomers might most effectively search for technosignatures from other civilizations.

The Deep Space Network, operated by NASA, is a collection of massive ground-based antennas that keep humanity in touch with spacecraft far from Earth. It’s the reason we receive photos from Mars rovers, data from the James Webb Space Telescope, and updates from distant probes like New Horizons. These transmissions are powerful, steady, and — crucially — detectable far beyond our planet.

Joseph Lazio, project scientist at JPL and co-author of the study, explained: “NASA’s Deep Space Network provides the crucial link between Earth and its interplanetary missions like the New Horizons spacecraft, which is now outbound from the Solar System, and the James Webb Space Telescope. It sends some of humanity’s strongest and most persistent radio signals into space, and the public logs of its transmissions allowed our team to establish the temporal and spatial patterns of those transmissions for the past 20 years.”

By matching transmission logs with spacecraft positions, the team mapped out exactly when and where our signals were most likely to spill into the cosmos. The patterns they found carry big implications.

The analysis revealed that most DSN transmissions were directed along the ecliptic plane — the flat path where planets orbit the Sun. Nearly all signals followed this “dinner plate” shape of the solar system, rarely venturing at steep angles.

Much of this activity centered on Mars, humanity’s most explored neighbor. Communications with probes and rovers on the red planet produced a predictable flow of signals. As Pinchen Fan, lead author of the paper and a graduate student at Penn State, put it: “Humans are predominantly communicating with the spacecraft and probes we have sent to study other planets like Mars. But a planet like Mars does not block the entire transmission, so a distant spacecraft or planet positioned along the path of these interplanetary communications could potentially detect the spillover.”

That spillover becomes especially noticeable during planetary alignments. When Earth and Mars align from an outside perspective, transmissions have a 77% chance of being intercepted — a strikingly high probability compared to the near-zero odds of detection at a random moment. Even alignments with other planets boost chances to 12%.

For any hypothetical alien civilization, these windows would be the best time to eavesdrop on Earth. For us, they offer a guide: exoplanet systems with similar alignments might be the best hunting grounds for alien technosignatures.

Astronomers already rely on planetary alignments to detect exoplanets. By observing a host star’s dimming when a planet passes in front of it, telescopes reveal worlds orbiting faraway suns. The same strategy could be applied to SETI: if alien civilizations transmit during alignments, their signals may be easier to spot.

Fan noted the importance of new instruments for broadening this work. “Because we are only starting to detect a lot of exoplanets in the last decade or two, we do not know many systems with two or more transiting exoplanets. With the upcoming launch of NASA’s Nancy Grace Roman Space Telescope, we expect to detect a hundred thousand previously undetected exoplanets, so our potential search area should increase greatly.”

This expected wave of discoveries could reshape SETI strategies. Instead of randomly scanning the skies, astronomers could focus on systems where geometry boosts the odds of detecting technosignatures.

The study also calculated just how far DSN transmissions might reach. Using equipment similar to our own, an alien civilization within 23 light-years could detect an average DSN signal. That’s a surprisingly wide footprint. Within this radius lie dozens of nearby stars, many with their own planets.

The implications are profound. Civilizations in these systems — especially those aligned edge-on with our solar system — would have a much better chance of noticing us. In effect, our deep space communications already make Earth visible in a cosmic neighborhood spanning dozens of star systems.

Radio isn’t the only way humanity communicates across space. NASA is testing laser communication for interplanetary missions. Lasers would reduce spillover, making them harder to detect by accident. Yet if aliens prefer precision over leakage, they might use lasers as their technosignatures.

The researchers suggest that their alignment-based strategy could apply here too. While lasers may be narrower, alignments still improve chances of detection. Any civilization sending powerful, directed messages might reveal itself during predictable orbital events.

Jason Wright, director of the Penn State Extraterrestrial Intelligence Center and co-author of the paper, highlighted the broader meaning of the work: “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. Using our own deep space communications as a baseline, we quantified how future searchers for alien intelligence could be improved by focusing on systems with particular orientations and planet alignments.”

In other words, the signals we send today could be the very same kinds of technosignatures we should be looking for tomorrow.

SETI researchers often face the daunting task of deciding where to point their telescopes. The sky is vast, and technosignatures could take many forms. By quantifying the patterns of our own emissions, this study offers a practical roadmap: search systems where alignments amplify the odds.

The work underscores a central idea in SETI. Intelligent civilizations, if they exist, may share common technological needs. Just as our spacecraft require robust communication links, theirs might too. And just as our transmissions cluster around planetary alignments, so might theirs.

In the end, the study does more than measure radio waves. It suggests a new way of thinking about interstellar communication. Rather than searching blindly, astronomers can use the rhythms of planets as guides. Alignments, orbits, and system geometry may act as natural markers where technosignatures are most likely to appear.

For anyone invested in the search for life beyond Earth, this offers hope. It’s not just about waiting for a lucky signal. With careful planning and smart use of cosmic geometry, SETI can become more strategic, more targeted, and — perhaps — more successful.

Research findings are available online in The Astrophysical Journal Letters.

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