Picture an ice-covered landscape, rough and rocky. Plumes of water vapor erupt from the surface. Tendrils of algae lurk in the bright white glaciers. Leagues below the surface, microorganisms and other creatures cluster near hydrothermal vents, fissures in the ocean floor where life can thrive.
This could be the scene on Europa, a moon of Jupiter where life could have sparked like it did on Earth.
We may have a chance to discover if this is really the case. Very soon, NASA will launch the space probe Europa Clipper, one of the most ambitious missions in its storied history, to investigate Europa’s potential to harbor life. Its findings may help confirm, as some would expect, that all life in the universe originates through a shared evolutionary pathway. Or the investigation may stumble on something radically unexpected that suggests life can take root in far more ways that we’ve only begun to comprehend. Either discovery would force us to reconsider much of what we know about biology and the origin of life.
Clipper is one of the most vital astrobiology projects yet aimed at answering the question of whether we are alone in the universe — a goal that should be NASA’s highest priority. The agency is best known for its human exploration missions, sending astronauts into orbit and to the surface of the moon, and being the driving force behind the International Space Station (which has been occupied by humans continuously since 2000). NASA hopes to resurrect the glory of Apollo with Artemis, its successor lunar exploration program to send astronauts back to the moon. But rather than pursue self-mythologizing goals of colonizing other worlds, NASA should do more to invest in and develop missions that more directly and intimately study extraterrestrial life and make them the lodestar of the agency.
Our cosmic backyard is brimming with planets and moons that might be ripe for alien life-forms to flourish. Astrobiologists think Europa is one of the most promising places to find extraterrestrial life despite its harsh conditions unsuitable to humans. The moon is believed to be encrusted with a 10-to-15-mile-thick ice shell. Sunlight cannot penetrate more than a few meters. Europa’s surface temperatures at its Equator at midday never rise above a frigid negative 225 degrees Fahrenheit. Its thin oxygen atmosphere provides no shield for the incessant radiation; even wearing a spacesuit, a human being would be hit with a lethal dose in under 24 hours.
Yet Europa seems to have the ingredients needed to stimulate life: water, hydrogen, carbon, oxygen, nitrogen, sulfur and phosphorus. These elements are churning together in a liquid water ocean sitting below the icy shell and warmed thanks to the massive friction induced by Jupiter’s awesome gravity. These conditions could have seeded strange cousins of earthly life-forms in the ocean’s depths near hydrothermal vents.
When Clipper arrives at Jupiter’s system in 2030, it will perform dozens of flybys of the moon and get as low as 16 miles above Europa’s surface. Its suite of instruments will map nearly the entire surface of Europa and photograph the icy world in visible light, infrared and ultraviolet. It will acquire as much data as possible about the chemistry of the interior ocean. It will analyze potential vapor plumes that may vent out into the atmosphere, which could be the best opportunity to understand what the liquid ocean is harboring.
Given how inaccessible the ocean is, Clipper is unlikely to find definitive proof of alien life. (Though never say never.) But it may find complex organics compounds important to sustaining bacteria or other microorganisms. The hope is that by mapping the surface, NASA can identify sites in the ocean under the icy crust that could be home to life. Future engineers who can build more audacious missions may be able to drill through the ice and explore these sites in depth.
Clipper’s scientific objectives are a refreshing break from the 20th century’s Space Age. Back then, NASA was dominated by missions designed to fulfill dreams of human colonization of outer space. Neil Armstrong’s “one giant leap for mankind” was not just a triumphant end to the Cold War competition with the Soviet Union to put humans on the moon first; his boot print was also tangible evidence that humans could travel between celestial bodies and survive elsewhere.
Residues of the Space Age propel the U.S. space program today. Space Force, a new military branch that cost the federal government $29 billion in 2024 alone, recalls Cold War fears of planet-wide warfare. The International Space Station has long been lauded as a beacon of peace and cooperation in space, but it also excludes Chinese participation and is a point of nervousness amid deteriorating American-Russian relations. The Artemis moon program — egregiously over budget and repeatedly delayed — will scout out locations for permanent lunar outposts as a steppingstone to Mars. And there is the rise of private companies like SpaceX that build their own rockets and spacecraft for crewed travel, often with the help of government contracts.
The Europa Clipper mission represents a sea change for NASA. After all these decades, we’re witnessing missions that are more intensely devoted to investigating alien — not human — habitability. In 2028, NASA will launch its Dragonfly mission to Saturn’s moon Titan and investigate its ocean and methane seas. The detection of a peculiar gas emanating from Venus’s clouds hints at the presence of biological activity — and a pair of missions beginning next decade may confirm these suspicions.
There are many other worlds in the solar system to explore. Saturn’s moon Enceladus has a subsurface ocean that may be habitable to life of some sort. Jupiter’s moon Ganymede is also a worthy candidate. The presence of water on Ceres, the only dwarf planet in the asteroid belt, raises even thin hopes that life could have arisen there.
Journeys to alien worlds are crucial if we’re to solve the profound and abiding mystery of the origin of life and learn whether we’re alone. That, to me, sounds like a much more worthy endeavor of our energies than our longstanding treatment of space as a void waiting to be conquered.
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