What Are Technosignatures?
Technosignatures — literally “technological traces” — are any observable evidence of a technological civilization beyond Earth. NASA defines them as any observable evidence of the manufacture or use of technology by a civilization other than our own. Unlike biosignatures, which search for evidence of life, technosignatures search for evidence of technology.
Classical SETI (Search for Extraterrestrial Intelligence) focused on radio signals. Since 1960, when Frank Drake launched Project Ozma at the Green Bank observatory, the first modern attempt to detect interstellar radio transmissions, the search has centered on narrowband radio transmissions. But that is changing. As of 2026, science is not limited to radio — searches are happening in infrared, in exoplanet spectra, in space debris, and even in seabed sediments on Earth.
Why Different Approaches?
Radio has two major limitations. First, radio waves travel at the speed of light, but the universe is vast. A signal sent thousands of years ago may only be arriving now. Second, if another civilization exists, why would it broadcast in the very band we are searching? The answer: it might not.
This is precisely why approaches based on physical evidence are developing. A civilization that consumes energy must dispose of that energy somewhere. And that creates observable traces.
Dyson Spheres and Waste Heat
The best known of the proposed technosignatures is the Dyson sphere — a hypothetical structure that surrounds a star and captures its energy. The idea was proposed by Freeman Dyson in a 1960 Science paper. The logic is simple: if a civilization needs ever more energy, why not capture all of the star’s output?
A complete Dyson sphere is physically unrealistic — there is not enough material. But partial structures, called Dyson swarms, could exist. And the key point is that even a partial structure that captures a fraction of a star’s energy must dispose of that heat somewhere. And that is exactly what we can detect.
Such a structure would look in the infrared like an overly hot star. Instead of shining only in visible light, it would have a large excess at longer wavelengths. This signal would be very difficult to explain by natural phenomena.
A cautionary example is the star KIC 8462852 (Tabby’s star): its irregular dimming sparked speculation about alien megastructures around 2015, but follow-up measurements pointed to dust in its vicinity — a textbook case of a tempting technosignature with a natural explanation. See Boyajian et al. (2018).
Laser and Other Signals
Beyond infrared, there are other paths. Laser communication is one. Unlike radio waves, which spread in all directions, a laser beam can be aimed at a specific target. This means that if another civilization communicates by laser, the signal would be much fainter — and much harder to find.
The Laser SETI project focuses on this approach. It uses specialized detectors capable of capturing very brief flashes of light across a wide spectrum. In 2024, a new method for searching archival Green Bank Telescope data with a narrowband technique was described (arXiv:2412.05786) — a partial methodological contribution, not a general review. The general review of all possible technosignatures — from industrial pollutants in exoplanet atmospheres to artificial lights on a planet’s nightside — came in 2026 (arXiv:2605.21093).
Breakthrough Listen and Other Projects
Breakthrough Listen is among the most extensive technosignature search programs. Announced in 2015 (observations running since January 2016), it has surveyed thousands of stars and dozens of nearby galaxies (the stated goal is a million stars and about a hundred galaxies). Funded with 100 million dollars and aiming at a million stars, it uses some of the large radio telescopes on Earth, including the Robert C. Byrd Green Bank Telescope in West Virginia.
In 2024, a study was submitted for publication in The Astronomical Journal (arXiv:2412.05786; the arXiv metadata list no journal publication), describing a novel approach to analyzing Green Bank Telescope data. The authors developed an algorithm capable of detecting technosignatures in data that previously could not be efficiently processed. Results: no confirmed signals — but the methodology matters.
Other approaches include:
- JWST (James Webb Space Telescope): Can analyze exoplanet atmospheres. Searches there are not only for life (biosignatures) but also for industrial pollutants that could signal technology.
- Lunar far-side radio telescopes: The Moon’s far side is an ideal location for radio observations — no interference from Earth. Proposed missions would place radio telescopes there that could search for signals we cannot capture as of 2026.
- Searching for artifacts in our galaxy including the Solar System: Some researchers propose searching for evidence of technology in our galaxy, including nearby — for example, abandoned probes or artificial structures.
What Does Current Science Say?
The most recent (2026) comprehensive review of all possible technosignatures was published in 2026 on arXiv (arXiv:2605.21093). The authors describe a broad spectrum of possibilities — from artificial lights on planets, to industrial chemical substances in atmospheres, to changes in the nitrogen cycle caused by agriculture. All share one thing in common: they are evidence that technology exists somewhere. The systematic framework for the field was set by a 2018 NASA technosignatures workshop report summarizing results and priorities.
At the same time, it is important to note that while searching for biosignatures has a clear goal — finding evidence of life — searching for technosignatures is broader. It could reveal a civilization that has long been dead, or one that does not want to be found.
Conclusion: Why Try?
Searching for technosignatures is not just a game for the curious. If we found evidence of another civilization, it would transform our understanding of the universe and our place in it. And even though nothing has been found yet, every unsuccessful attempt says something — about how the universe looks, and about what possibilities we have.
Sources
- NASA Technosignatures definition — science.nasa.gov/universe/search-for-life/searching-for-signs-of-intelligent-life-technosignatures/
- Breakthrough Listen: A Novel Technosignature Search (2024) — arxiv.org/abs/2412.05786
- The Search for Technosignatures: a Review of Possibilities (2026) — arxiv.org/abs/2605.21093
- Dyson Sphere — en.wikipedia.org/wiki/Dyson_sphere
- Technosignature — en.wikipedia.org/wiki/Technosignature
- Laser SETI — laserseti.org/
- Project Ozma (1960), the first modern SETI experiment — seti.org
- Dyson, Search for Artificial Stellar Sources of Infrared Radiation (1960) — doi.org/10.1126/science.131.3414.1667
- Boyajian et al., the KIC 8462852 dimming mystery: dust (2018) — doi.org/10.3847/2041-8213/aaa405
- NASA technosignatures workshop report (2018) — arxiv.org/abs/1812.08681
- Breakthrough Listen, program goals — breakthroughinitiatives.org
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