Here’s why I’d like to take a trip to Antarctica.
The Kepler spacecraft has changed the world. It has discovered 974 planets we’re sure of (as of June 2014), and there are 3,601 candidate planets awaiting confirmation. They’re exoplanets, orbiting other stars in our galaxy. A few are Earth-like—well, not far from our planet’s size and in the habitable zone of their respective stars. At their distance from their star, they wouldn’t be too hot or too cold for life that we understand. These results have led us to conclude that there may be 17 billion Earths in our own galaxy.
In 1950, well before Kepler’s findings, Enrico Fermi and some colleagues were discussing the possibility of life elsewhere in the galaxy. He offered what’s now known as the Fermi Paradox: if the universe is as old as we think it is, with its vast number of stars, odds are that extraterrestrial life is common. And we can even expect some technologically advanced species. Kepler’s many planets make Fermi’s case even stronger. So, why haven’t we heard from them? Why haven’t we at least found evidence of that life? Years later, John von Neumann’s interest in self-replicating machines inspired his answer: maybe so-called von Neumann probes are already here. Self-replicating devices may have made their way across the galaxy and now lie dormant and undetectable, only infrequently transmitting information about Earth to their planets of origin.
I submit that a probe like this, something tiny enough and transmitting in a way we would not detect, might go unnoticed. Something small enough might appear to us as a dust mote, or a micrometeorite. Thousands of tons of interplanetary and interstellar debris land on Earth every year. In fact, whether or not a working von Neumann probe has ever made it to Earth, bits of failed probes would be continually circling gravitational drains throughout the galaxy. They would collect on planetary surfaces like the little shattered bodies of diatoms, whose calcium-rich remains litter the ocean floor. Such tiny interstellar probes might be ground up over the course of thousands, maybe billions, of years as they tumble through space and end up as particles on the interstellar wind.
And if so, we might find some in Antarctica. That’s where you can pick up micrometeorites off the ground—bits of black jetsam on a beach of snow and ice. So, here’s a Spacecraft-a-Week idea turned on its head. Rather than designing a spacecraft, let’s see if we can discover someone else’s. Let’s try to identify space-technology debris from a long time ago, maybe a galaxy far, far away. What we learn from very careful analysis of the dust that has been falling on Earth for eons may lead us in unexpected directions. It may teach us how to build spacecraft we cannot conceive of now.
This idea has been in the back of my mind for about 40 years. When I was six, I visited a beach in Italy, a town known as Anzio, where Nero once had a villa. At some point the coastline had eroded, and the sea claimed the villa. But wading through the water near where this villa once lay, I found ellipsoidal bricks, rounded-off bits of tile, even pieces of mosaics. The surf had ground them down, but what I saw was unmistakably building material: cement in a matrix holding stones (concrete!). Right-angle shapes (corners of bricks!). A smooth piece of marble with one unaccountably flat face (tile!). A chamfered glass square that was certainly not an igneous rock. Even a kid can tell the difference between what’s natural and what’s man-made.
Craig Ventner did something related a decade ago. His research team scooped up a sample of the Sargasso Sea to understand the genetic diversity of the oceans. Sequencing the genes of this large sample revealed enormous diversity—far more species than we knew. His is a similar approach because he exploited the power of computation to address a problem that is simply intractable on the scale of what humans can accomplish. And he was interested in a statistical result. So am I. How much interplanetary dust is the result of someone’s handiwork? I expect that the fraction approaches zero, but I also speculate that it is not zero.
What we’ll need is a very large sample of micrometeorites, a microscope that captures digital images, a spectrometer, some fast computers, and a smart algorithm (that’s the hard part) that can identify what’s natural and what’s not. This project would be a mechanical version of what SETI has attempted. Rather than looking for intelligent radio-frequency signals among the many natural emissions from the stars, we would seek out unnatural dust particles. Craig Ventner’s expedition and later analyses were funded by grants totaling well over $25M. I think we could do it for that amount.
The next step would take a little more money, but not unreasonably more. The particles that survive the fall to the surface of the Earth represent a very specific subset of all the stuff that’s circling our gravitational drain right now. Only the particles with a low-enough ballistic coefficient land intact, and we would find only those portions of larger bodies that can survive the heat of reentry. The rest vaporizes. But we may discover artificial materials that have been designed to survive the heat of entering a planet’s atmosphere, solutions we have not yet come up with. Whether those materials are artificial or natural, those solutions are important. They may improve our ability to send mass back from the International Space Station or, in the longer term, land people on Mars. And that’s just the beginning.
if this Antarctic micrometeorite survey is at all successful—and we would already have changed the world at that point—we should launch a spacecraft to follow up. I suggest we send it to the Moon. Consider one or more small rovers, maybe CubeSat size, equipped with a microscope and that same algorithm, beachcombing the lunar surface, picking out those unexpected shapes and materials: polymers, alloys, and composites that are one in a million and have no business being there, like Andy Dufresne’s piece of black volcanic glass. The rover transmits that one-in-a-billion image to Earth, along with its spectral data, for us to analyze. Those candidate particles, like the SETI signals or Kepler’s uncertain stellar-wobble data, don’t all pan out. But I’ll be satisfied with just the one.