A pair of research papers presented in recent weeks is reshaping the search for extraterrestrial intelligence, steering it away from a decades-long focus on interstellar radio signals and toward the detection of physical technosignatures inside the Solar System. An article submitted to the International Astronomical Union by T. Joseph W. Lazio argues that current data cannot exclude the possibility that non-human civilisations have sent probes into our cosmic neighbourhood, while a separate preprint by Oxford astrophysicist Brian Lacki contends that the Moon’s regolith could harbour pulverised remnants of long-extinct alien technology. The immediate effect is a widening of the SETI aperture: the hunt now formally includes artefacts, debris and even dust grains that may have drifted into our planetary backyard.

The logic rests on a practical limitation. For decades, SETI has largely listened for electromagnetic anomalies—radio transmissions or laser pulses—yet even human civilisation is growing radio-quiet as communications infrastructure evolves. Lazio notes that vast swaths of the Solar System remain surveyed at resolutions too coarse to spot objects the size of a probe; a kilometre-scale body in the outer system could pass unnoticed in current imagery. He proposes that machine-learning algorithms be trained on the growing archives from space missions and observatories to flag objects with unusual trajectories, temperatures, compositions or shapes. The 2020 SO episode, in which a suspected asteroid turned out to be a spent Centaur rocket stage, illustrates both the promise and the ambiguity: identifying an anomaly is one thing, confirming its artificial origin quite another.

Lacki’s paper, not yet peer-reviewed, takes the physical argument further. He theorises three classes of passive technosignatures—occulters that block starlight, glinters that reflect it like giant mirrors, and diffusers that scatter light in distinctive spectra—and then follows a chain of destruction. If an advanced civilisation built Dyson-scale structures, collisions and erosion could grind them into “technograins”, dust particles that escape their host system on solar wind. As the Solar System orbits the Milky Way, planets and moons sweep through interstellar material; the Moon’s geologically inert surface could have preserved such grains for billions of years. The search, Lacki writes, would be not for “macroscopic objects deliberately placed, but dust, the unintended microscopic testament to our possible predecessors.”

Viewed from terrestrial remote-sensing science, the tools to conduct such a search are maturing. NASA’s PACE satellite, designed primarily for ocean and atmosphere observations, has just completed its first year of hyperspectral imaging, distinguishing chlorophyll, carotenoids and anthocyanins in vegetation across continents. The same capacity to resolve subtle chemical signatures from orbit is precisely what would be needed to scan planetary surfaces for anomalous materials. Meanwhile, physicists in Tehran and elsewhere underscore the immense energy and time-dilation barriers to interstellar travel, reinforcing the view that relics are more plausible targets than active visitors. The next factual milestone is the peer review of Lacki’s preprint, while Lazio’s framework is expected to inform proposals for AI-assisted surveys of archival data from missions such as the Lunar Reconnaissance Orbiter.