Desperately Seeking Space Friends

Toward the end of The Pale Blue Data Point, Jon Willis asks, “How can we, without ever having discovered the merest cellular speck of evidence for alien life, call ourselves astrobiologists?” It’s a serious question. We would be wary of a physician who had never seen a patient, a plumber who had never touched a pipe, or a pilot who had never been in a cockpit. Yet the very raison d’être of astrobiology is to make pronouncements about life “out there”— life for which, so far, we have no evidence.

Astrobiology is a relatively new branch of science. Universities do not yet have astrobiology departments, so astrobiologists are generally found in astronomy or physics departments. (Willis, for example, is a professor in the University of Victoria’s astronomy department.) Regardless of where they sit, astrobiologists pursue a puzzle that has tantalized humankind since we first looked up at the stars: Who or what is out there?

That inquiry began to crystallize into something like its modern form in the sixteenth and seventeenth centuries, when it became clear that Earth is a sphere hurtling through space, perhaps not so different from the other “wandering stars”— or planets, as we now call them — that adorn the night sky. When Darwin put forward his theory of evolution in the nineteenth century, it was only natural for others to ask what creatures might have evolved elsewhere.

Willis’s title is a play on Carl Sagan’s poignant description of how Earth appeared in a photograph taken by Voyager 1 as it was heading toward the edge of the solar system some thirty-five years ago. Sagan referred to our world as a “pale blue dot” that covers mere pixels on that spacecraft photo. To us, of course, our planet is much more than a dot, and, as Willis emphasizes, it may tell us a great deal about possible realms, and possible life forms, in the far beyond.

To that end, Willis takes us on a tour of some of Earth’s most seemingly inhospitable environments. Aboard the research ship E/V Nautilus, for instance, he pondered the hydrothermal vents on the sea floor off Vancouver Island, known to harbour weird worms and micro-organisms. Examining the video and data collected by submersible vessels launched from the ship was “a deeply unfamiliar experience, one for which the language of the surface world was lacking in appropriate imagery.” Later he visited the Australian deserts where our planet’s oldest fossils are found. They’re actually microfossils, not visible to the unaided eye, but their unfathomable age — the single-celled creatures they record are fifty times more remote from our own time than the dinosaurs — had the author mesmerized. Clambering over those ancient rocks in 30-degree-plus heat, he was deeply moved: “As I looked at the fossils in front of me, I could feel the years slipping away, all 3.35 billion of them, as my mind’s eye took in a view of a forgotten world at once alien and familiar.”

Willis also visited a Chilean mountaintop, not to find any particular organisms (aside from human astronomers) but to visit our most sophisticated observatories. After a night of stargazing, he was once again in a poetic mood. “The first few steps upon the trail would leave the telescopes behind me while the stars overhead formed a silent, glittering dome,” he writes. “The barest dusting of silver light would settle on the mountainside, good enough for someone familiar with the path but not much more than that. However, the insubstantial, barely perceptible light would provide a subtle tingle of kinship, of connection with the night sky, as each photon that my eye sensed came not from scattered or reflected light emitted by our own sun but from the luminous fires of suns far beyond our solar system. Under such skies on such nights, those stars would not feel so very distant any more.”

Poetry is fine, of course — but is anyone actually out there? The prevalence of living things even amid Earth’s most challenging environments suggests that life will “find a way,” but searching for clues to the universe in our backyard has its limitations. Yes, life has flourished here for at least three billion years, but it can flourish only where it arose in the first place, and we have no idea if it arose anywhere else.

The evidence from our solar system is inconclusive. For decades, there’s been speculation that there is or at least was life on Mars, an idea bolstered by models that suggest the planet was much warmer and wetter millions of years ago. (From time to time, Mars mania intensifies its grip. For a terrific analysis of the canals that Percival Lowell claimed to have found at the turn of the twentieth century, see David Baron’s excellent The Martians, published last summer. And for the 1990s hype over a meteorite recovered in Antarctica that supposedly contained fossilized micro-organisms, type “Bill Clinton Martian meteorite” into YouTube.) Willis, to his credit, is cautious: “We risk drifting on a tide of speculation here, cast loose from the secure tether of primary evidence.”

Beyond Mars lie Jupiter and its enigmatic moon Europa. Although Europa is covered by ice sheets, scientists believe that liquid water lurks below; how close this water comes to its surface remains unknown. The Europa Clipper, launched in 2024, is due to arrive at Jupiter toward the end of this decade and will use radar to probe the moon’s interior. A lander that would actually collect data from its surface would be even more revealing, but, given NASA’s financial woes, it is unclear if or when this might happen. Saturn’s icy moon Enceladus is also suspected to have oceans below its surface.

As for worlds beyond our solar system — well, there are a lot of them. More than 6,000 exoplanets (planets orbiting stars beyond our own) have been identified thus far. While we won’t be sending spacecraft to these places any time soon, examining them with ground-based or orbiting telescopes is (relatively) cheap. Willis highlights NASA’s Transiting Exoplanet Survey Satellite and the European Space Agency’s Gaia mission. TESS, launched in 2018, is searching for so‑called short-period exoplanets: planets that circle their host stars in less than thirteen days. So far, it’s found hundreds of them. Launched in 2013, Gaia takes a different approach. It’s been mapping the stars (a field known as astrometry) within our galaxy in unprecedented detail, and by monitoring any stars that exhibit a slight wobble, it can deduce which ones harbour planets. Another space traveller is the James Webb Space Telescope, launched in late 2021, which has already analyzed the atmospheres of several gas giants — large exoplanets composed mostly of helium or hydrogen, similar to Jupiter and Saturn.

Whether creatures are stirring anywhere out there we simply don’t know. We’ve been listening with our radio telescopes for any seemingly unnatural signals since the 1960s, but thus far not a peep has been heard from E.T. Perhaps we’re more likely to see evidence for an alien civilization’s machines than for the creatures that built them — an idea that underscores the search for “technosignatures.” In 2015, astronomers found that an object known as Tabby’s star undergoes strange periodic dimming over short time scales. There was speculation that it could be a Dyson sphere, a megastructure used by an alien civilization to capture most of the energy of its host star. (The notion is named for Freeman Dyson, who contemplated such infrastructure in the 1960s, though a similar idea had appeared in a science fiction novel thirty years earlier.) The more sober viewpoint is that the periodic dimming is caused by comets or dust orbiting the star.

We’ve also seen objects such as ‘Oumuamua, a small, cigar-shaped (or possibly pancake-shaped) rock that zipped through our solar system in 2017. The following year, the Harvard astronomer Avi Loeb published a peer-reviewed article in which he and his collaborator suggested it could have been an alien spaceship — a view that Willis recognizes as groundless speculation. But Loeb kept pushing his theory, seeming to welcome the media attention it garnered. The whole affair, Willis writes, “has come to resemble a modern-day crusade that Percival Lowell, famed interpreter of Martian canals, would be proud of.”

If we ever hear from E.T., what sort of a conversation might we have? Willis points to Earth’s other intelligent creatures, with whom we struggle to communicate (indeed, we struggle to keep them from going extinct). Take dolphins. Scientists have been studying their communication for decades, but our evolutionary paths diverged some 100 million years ago, and nothing like a conversation between humans and dolphins has ever happened. It’s not even clear if such a thing could happen. Willis, aware of these limitations, writes, “Encounters with our fellow creatures from the animal kingdom, even though desperately important as we seek to understand and protect our natural world, can only serve as practice questions while we wait for the real test of our communication skills to arrive over the galactic airwaves.” (For a fascinating exploration of just how different alien bodies and minds might be from our own, check out Daniel Whiteson and Andy Warner’s recent Do Aliens Speak Physics?)

Few would argue with Willis’s view that if we do one day detect extraterrestrial life, it will be a game changer. A clearly intelligent signal from the depths of space, even if we can’t decipher it, would “represent an utterly profound discovery,” one that would instantly “change our perspective on our place in the cosmos.” In another chapter he makes a slightly different claim, suggesting that the discovery of a “potentially life-bearing exoplanet” would relieve our feeling of cosmic isolation: “Our sense of the cosmos will be forever changed, and our wanderings beneath the distant stars will, from that moment on, be a little less lonely.”

It’s a compelling notion, but I think it very much depends on what we find. If space dolphins or celestial jellyfishes live somewhere beyond Alpha Centauri, great — but then what? It’s true that many of us are befriending chatbots (for better or for worse), and Tom Hanks’s character became best buds with a volleyball on that deserted island in Cast Away. But I suspect that only creatures that have hopes and dreams and fears similar to our own would actually have much impact on human loneliness. And finding that sort of creature may be a long shot indeed.