Have we been too hasty to dismiss the possibility of interstellar spacecraft nearby? Are there limits to our sampling depth that we are not fully aware of?

To help find out, in 2022 NASA commissioned an independent study to determine whether current satellites and surveillance systems have sufficient sampling depth to detect “unidentified anomalous phenomena,” or UAPs (government talk for what could be alien spaceships). The researchers’ conclusions:

NASA’s fleet of Earth-observing satellites collect the most data within the Earth system, yet they typically lack the spatial resolution to detect relatively small objects such as UAP…

Commercial satellite constellations provide imagery at sub- to several-meter spatial resolution, which is well-matched to the typical spatial scales of known UAP… The limitation on this data is that at any given time most of the Earth’s surface is not covered by commercial satellites at high resolution—for a particular UAP event, we will need to be fortunate to obtain high-resolution observations from space.

It seems that Earth’s atmosphere is unintuitively large, just as microorganisms are unintuitively small. While the atmosphere is so transparent and so close, we do not have a complete grasp of everything inside it. Consider that the average depth of Earth’s oceans is 2.3 miles, while the atmosphere extends up to about 6,200 miles, where it gradually transitions into space.

If Earth’s atmosphere is truly a rock unturned, why aren’t more astrobiology-minded scientists scrambling to take a peek? (One notable exception is Harvard University astrophysicist Avi Loeb, co-founder of the Galileo Project, an effort to search for and study evidence of UAP activity on or near Earth.) Just as Fracastoro’s colleagues made a series of assumptions about the nature of disease, so has the scientific community made a series of assumptions about technological species. Foremost among these is the idea that alien spacecraft in the solar system or cosmic civilizations percolating through the Milky Way would emit unmistakably prominentsignals. This notion encourages us to look for displays of cosmic technological might that could be considered absurdly wasteful and impractical. In turn, it discourages us from seeking out quieter, more subtle forms of alien technology, even though they may be more common.

From our privileged position in history, we know that advances in energy use often come with increases in efficiency, not simply increases in size or expansiveness. Think of the modern miniaturization of smartphones versus the mid-20th-century trend of computers that filled up whole rooms. Perhaps we should be looking for sophisticated and compact alien spacecraft, rather than motherships spewing misused energy.

With this in mind, we can imagine going back to 1950 and rephrasing Fermi’s famed lunchtime question.

His shirt ripples in a hot desert wind. He looks up at the sky.

“Where are all the loud, obvious indicators of aliens?” he asks.

When phrased like this, the simplest explanation stands out like a sore thumb. Perhaps aliens don’t leave loud, obvious indicators. Perhaps their vehicles are nearby, and perhaps no one has bothered to check properly—yet.