If advanced civilizations are out there, we'll find the evidence on the moon. We're on a mission to get that sample and bring it back to Earth.
Radio SETI, the search for extraterrestrial intelligence by listening for alien radio signals, can only hear a civilisation that's transmitting right now, on a frequency we happen to be watching, close enough that its signal still reaches us. It's tuned to the living, the loud, and the nearby.
A detection would be extraordinary. But silence tells us almost nothing: most of cosmic history is already out of earshot. The dead don't broadcast.
Every spacefaring civilisation, past or present, sheds material. Not monuments, but debris: micron-scale grains scattered by the same blind physics that spreads our own orbital junk. Given billions of years, some of it drifts across the galaxy. And some of it is likely on our moon.
Refractory grains roughly 0.3 μm across can survive transport across the interstellar medium and arrive slowly enough to be captured, intact, on the Moon.
A micron or sub-micron technogenic grain: the accidental by-product of a spacefaring civilisation, drifting across interstellar space like ordinary dust. Unlike a radio signal, it stays readable across gigayear timescales. Arkhipov’s insight, back in the 1990s: the most common alien artefacts won't be deliberate monuments. They'll be residual debris, scattered far beyond their makers’ control.
A grain starts as the debris of a distant civilisation, then drifts across the interstellar medium for hundreds of millions of years. Gas drag, sputtering, and the push of starlight all shape the journey before a few survivors ever reach our Solar System.
No air, no oceans, no plate tectonics. A surface that's been collecting interstellar material for a third of the age of the universe, and erasing almost none of it.
Most infalling grains never make it down. Sunlight's radiation pressure turns away the smallest, and only those on the right path, moving slowly enough, survive the landing. But across billions of years, just enough arrive. And on the Moon, what lands stays put: no wind, water, or tectonics to bury or erase it, only slow space-weathering into a background we can characterise.
Here's the plan: lift a cubic metre of the Moon, then run it through a pipeline that inspects it grain by grain.
One cubic metre sounds tiny, but it isn't a small sample, it's a four-billion-year exposure. The upper regolith has been catching infalling material since the Solar System was young, so a single cubic metre already holds on the order of 10¹² grains in the size range we care about. The natural background is well characterised, so a genuinely technogenic grain stands out against it. And the population is large enough that even a clean null is decisive: finding nothing rules out more than 0.09 Earth-masses of dispersed, long-lived technomaterial per Sun-like star. Either way, we learn something real.
There are three ways to look for technological life. Two of them need luck or millennia. The third just needs a sample and a microscope.
Interstellar travel is beyond reach for any near-term mission. We can't go and visit the evidence.
Radio SETI needs a transmitter that's live, aimed near us, and detectable today. It can't hear the past.
If the material exists, it's already on the Moon. Bring a sample home and put it under a microscope. We can do that now.
If they exist, they're already here, resting in the dust. We don't have to wait for a signal. We just have to go and read it.
Moonblock is a research lab. We're building the instrument and the imaging pipeline that will read the regolith. If you fund deep science, build precision instruments, or want to collaborate, let's talk.