For as long as we have looked up at the stars, we have wondered if we are alone in the universe. We have searched for signals, looked at distant planets, and explored our own solar system. For many years, most of this search focused on planets like Mars. But in recent decades, scientists have turned their attention to a more surprising and exciting place: a moon of Jupiter called Europa.
Europa is one of Jupiter’s four largest moons, about the same size as Earth’s moon. From the outside, it looks like a giant, icy cue ball, covered in cracks and streaks. But the real secret is not on its surface. Based on many years of data from spacecraft, scientists are almost certain that a deep, global ocean of liquid saltwater is hidden beneath that icy crust. This is not a small lake; this ocean is thought to hold more than twice as much water as all the oceans on Earth combined.
This discovery changed everything. Where there is liquid water, there is the possibility of life. This makes Europa one of the most promising places in our entire solar system to look for an answer to our biggest question. But what would actually happen if we found it?
Why Do Scientists Think Life Could Be on Europa?
When scientists look for life, they are not just looking for creatures. They are looking for three key ingredients that life, as we understand it, needs to get started. Europa seems to have all three.
The first ingredient is liquid water. Europa has this covered, with its massive, salty subsurface ocean. Scientists are very confident this ocean has been there for billions of years, giving life plenty of time to develop.
The second ingredient is chemistry. Life needs specific chemical building blocks, sometimes called the “CHNOPS” elements: Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, and Sulfur. These are the basic elements for building cells, proteins, and DNA. Scientists believe Europa has these elements. They were likely present when the moon first formed, and more could have been delivered over billions of years by comets and asteroids crashing into the surface. These chemicals could then mix into the ocean below.
The third ingredient is an energy source. This is the most important piece of the puzzle. Europa is too far from the sun for sunlight to reach its ocean, so photosynthesis is impossible. The energy must come from somewhere else. Scientists think the answer is Jupiter’s powerful gravity. As Europa orbits the giant planet, it is constantly stretched and squeezed by gravity. This process is called tidal flexing, and it creates a huge amount of friction and heat deep inside the moon’s core. This heat could be enough to create underwater volcanoes and hot springs on the ocean floor, known as hydrothermal vents. On Earth, our own deep oceans are dark and cold, but these hydrothermal vents are bursting with life. Microbes and other organisms thrive on the chemical energy and heat coming from the vents, in a process called chemosynthesis. Scientists believe this could be happening on Europa right now.
What Kind of Life Would We Expect to Find?
When we talk about “life on Europa,” it is very important to set the right expectations. We are not likely to find complex creatures like fish, squid, or the “Europans” you see in movies. The environment is extremely harsh. It is totally dark, under immense pressure from miles of water and ice, and has a different chemical mix than Earth.
If we find life there, it will almost certainly be microbial. This means tiny, single-celled organisms, similar to the bacteria or archaea we have on Earth. In fact, we have organisms on our own planet, called extremophiles, that give us a good model for this. Extremophiles are “extreme-loving” microbes that live in places we once thought were impossible for life. We find them thriving in boiling hot springs, in water that is saltier than the Dead Sea, in acidic pools, and deep inside the ice of Antarctica.
The life on Europa would be the ultimate extremophile. It would be a simple organism that likely evolved to eat chemicals and minerals coming from the seafloor’s hydrothermal vents. It would be a life form that has never, ever seen sunlight and exists in a completely dark, self-contained world. But make no mistake: finding even a single, simple microbe on Europa would be the most profound scientific discovery in human history. It would prove that life is not a miracle that happened only once on Earth.
How Are We Trying to Find This Life?
We cannot just land on Europa and start drilling. The ice shell is believed tobe 10 to 15 miles (or 15 to 25 kilometers) thick, which is far deeper than any drill we have ever made on Earth. So, the first steps are to study Europa from orbit.
Two major missions are doing this right now. The European Space Agency (ESA) launched its Jupiter Icy Moons Explorer (JUICE) in 2023. While its main target is another moon, Ganymede, it will also perform two important flybys of Europa to gather data. The much more focused mission is NASA’s Europa Clipper, which launched in October 2024 and is scheduled to arrive at the Jupiter system in 2030. Europa Clipper is not designed to find life directly. Its main job is to act as a scout. It will fly by Europa nearly 50 times, using powerful radar to measure the exact thickness of the ice shell and confirm how deep and salty the ocean is. It will map the surface and identify “hot spots” where the ocean may be interacting with the ice.
There is also a very exciting possibility. Scientists have seen hints that Europa might be spraying giant plumes, or geysers, of its ocean water out into space through cracks in the ice. If these plumes are real and active, Europa Clipper could fly right through them. By “tasting” the spray, the spacecraft could analyze the ocean’s water for chemical signs of life, called biosignatures, without ever needing to land or drill a single inch.
What Would Happen Right After the Discovery?
If one of these missions found something, the news would not break overnight. A discovery this big would follow a very long and careful process. It would not be a single “Eureka!” moment but a slow, cautious series of steps.
First, the spacecraft would detect a “biosignature.” This would not be a photo of a creature. It would be a complex chemical pattern that is very difficult to explain with geology alone. For example, it might find a specific mix of amino acids or lipid molecules that, on Earth, are only made by living cells.
Second, the science team would spend months, or even years, trying to prove themselves wrong. This is a key part of the scientific method. They would ask: Could a non-living chemical reaction create this signal? Is the sensor on the spacecraft broken? Could the spacecraft have brought these chemicals from Earth? This last question, “forward contamination,” is the team’s biggest fear. They must be 100 percent sure they are not just detecting their own germs.
Third, after the team has failed to find any other explanation, they would write a detailed scientific paper. This paper would be sent to other scientists around the world for “peer review.” These other experts would try to find any flaws in the data or the conclusion.
Finally, only after the data has been checked, re-checked, and confirmed by the global scientific community, would NASA or ESA hold a major press conference. The announcement would be very careful. They would not say, “We found aliens.” They would say, “After rigorous testing, we have found evidence that strongly points to a biological origin for chemicals sampled in Europa’s ocean.” Despite this cautious tone, the world would instantly understand what it means. Studies on public reaction suggest that, contrary to movie portrayals of panic, the overwhelming global feeling would be one of wonder, excitement, and positivity.
How Would This Discovery Change Science Forever?
This discovery would completely rewrite our biology textbooks. Right now, we only have one example of life in the entire universe: Earth life. Every person, every plant, every animal, and every germ on our planet all share a common ancestor. We are all part of one “tree of life.” Because we only have one example, we do not know if life is a one-in-a-trillion fluke or a common, natural process.
Finding life on Europa would answer this question. Europa’s ocean is so isolated from Earth that any life found there would have to be a “second genesis.” It would mean that life started completely independently, all by itself, in a totally different environment. If life could start twice in one solar system (once on Earth and once on Europa), it would strongly imply that the universe is teeming with life. It would mean that life is not a miracle, but a natural result of geology and chemistry.
It would also be the birth of a new field of science: comparative biology. Scientists would be desperate to know what this Europan life is like. Does it also use DNA? Does it use the same set of amino acids and proteins? Or did it find a completely different way to “be alive”? Is its basic code something we cannot even imagine? Answering these questions would finally help us understand the fundamental rules of life itself, not just Earth life. This is why finding a single microbe on Europa would be a bigger discovery than finding the ruins of an ancient city on Mars. A Martian fossil could be related to us, as rocks are known to travel between Earth and Mars. Europan life would be truly alien.
What Rules Do We Have to Follow When Looking for Life?
When exploring worlds that could have life, space agencies follow a very strict set of rules called “Planetary Protection.” This is an international agreement, and it has two main goals.
The first goal is to protect the other world from us. This is called “forward contamination.” We must not contaminate Europa with microbes from Earth. Spacecraft like the Europa Clipper are built in special “clean rooms,” where engineers wear full-body suits. The hardware is scrubbed, baked, and blasted with radiation to kill as many Earth germs as possible. This is incredibly important for two reasons. First, we have a moral duty not to destroy a native ecosystem with our own invasive species. Second, if we did find life, we must be absolutely certain it is real Europan life and not just bacteria that hitched a ride from the launch pad.
The second goal is to protect Earth from the other world. This is “backward contamination.” This rule does not apply to orbiters like Clipper, but it would be the most important rule for any future mission that tries to bring a sample of Europa’s water back to Earth. This is the scenario you see in sci-fi thrillers, and scientists take it very seriously. Any returned sample would be treated as potentially hazardous. It would be sealed in multiple layers of containment and studied in a special, high-security lab (known as a Biosafety Level 4 facility) to ensure that no alien organism could ever escape and harm Earth’s environment.
How Would Finding Life on Europa Change How We See Ourselves?
The scientific impact would be huge, but the impact on humanity, philosophy, and our everyday culture might be even bigger. For all of human history, we have been defined by our uniqueness. We have told stories and built beliefs based on the idea that Earth is the single, special center of life.
Discovering that we are not alone would change that forever. Even if the life is just a microbe, it would prove that we are part of a much larger, living cosmos. The question “Are we alone?” would finally be answered with a clear “No.”
This would have a deep impact on our philosophies and religions. Many theologians and religious leaders have already discussed this possibility. Most major world religions are not as human-centric as some people think and would likely adapt to this new reality. For example, some Christian thinkers have explored how new life fits into their creation story. Some Islamic scholars note that the Qur’an already speaks of God as the “Lord of all worlds.” And some Jewish and Buddhist thinkers have long argued that humanity’s importance does not depend on being the only life in the universe. The discovery would not end religion, but it would certainly challenge us all to think bigger.
On a social level, this discovery could be a unifying force for humanity. In a world often divided by politics and borders, the knowledge that we are all “Earthlings” sharing a planet in a living universe could make our own conflicts seem smaller. It would mark a new era in our story, changing our place in the universe and forcing us to see ourselves, and our world, in a new light.
Conclusion
The search for life on Europa is not just another space mission. It is a deeply human quest to answer one of our oldest questions. We are now living in a time when we have the technology to actually find the answer. Missions like the Europa Clipper are the first wave of this incredible search, scouting the territory and checking the ingredients.
If they, or a future mission, find the evidence of life hiding in that dark, distant ocean, it will be a turning point for our species. It will prove that Earth is not the only living world, but just one of many. It will open a new chapter of science, philosophy, and exploration, and it will change how we see our place in the cosmos forever.
Finding life on Europa would be amazing, but it would also present us with a new, enormous choice. What would be our next step: to try and contact it, to study it from afar, or to declare Europa a protected wilderness and leave it alone?
FAQs – People Also Ask
What is a biosignature?
A biosignature is any sign, substance, or pattern that provides scientific evidence of life, past or present. It is not necessarily the life form itself. Examples include complex organic molecules like lipids or proteins, specific chemical ratios that are unlikely to be made by non-living processes, or even microscopic fossils.
How do scientists know there is an ocean on Europa?
Scientists are almost certain there is an ocean because of data from NASA’s Galileo spacecraft. Galileo measured Europa’s magnetic field. It found that as Europa moves through Jupiter’s powerful magnetic field, it creates a second, induced magnetic field of its own. The best explanation for this is a large, conductive layer inside the moon, and a global ocean of salty water is the perfect candidate.
Is Europa the only place in our solar system that might have an ocean?
No, Europa is not the only one. Several other moons are also thought to have subsurface oceans, making them “ocean worlds.” The most famous is Saturn’s moon Enceladus, which is known to spray its ocean into space through massive geysers. Jupiter’s moons Ganymede and Callisto, and even Saturn’s large moon Titan, are also believed to have oceans hidden under their crusts.
How thick is the ice on Europa?
Scientists are not perfectly sure, but estimates based on current models place the ice shell at around 10 to 15 miles (15 to 25 kilometers) thick. One of the main jobs of the Europa Clipper mission is to use ice-penetrating radar to get a much more accurate measurement of this thickness.
Will the Europa Clipper mission land on the moon?
No, the Europa Clipper is an orbiter. It is not designed to land. It will complete dozens of close flybys of Europa, some as low as 16 miles (25 kilometers) above the surface, to scan and study the moon. A future mission, often called a Europa Lander, has been proposed but is not yet approved or funded.
What is the difference between finding life on Europa and on Mars?
Finding life on either world would be historic. However, Mars and Earth are relatively close, and scientists know that rocks have been blasted from Mars to Earth (and from Earth to Mars) by asteroid impacts. This means if we found simple life on Mars, it is possible it could be distantly related to Earth life. Europa’s ocean is so far away and so isolated under miles of ice, it is almost impossible for it to have been contaminated by Earth. This means any life found on Europa would be a truly separate, “second genesis” of life.
How cold is the surface of Europa?
The surface of Europa is extremely cold. Because it is so far from the sun, the average temperature at its equator is about minus 260 degrees Fahrenheit (minus 160 degrees Celsius). At its poles, it can drop to minus 370 degrees Fahrenheit (minus 220 degrees Celsius). This is why the ocean can only exist as a liquid far below the surface, where it is kept warm by the moon’s internal heat.
What is tidal flexing?
Tidal flexing, or tidal heating, is the process that keeps Europa’s ocean liquid. Europa is in a slightly stretched-out (elliptical) orbit around Jupiter, and it is also pulled on by the other large moons. This causes Jupiter’s immense gravity to constantly stretch and squeeze Europa’s entire body. This constant flexing creates massive friction inside the moon’s rocky core, generating heat that warms the moon from the inside out.
Could Europan life be dangerous to humans?
This is a very common question and a key part of “planetary protection.” The risk is considered extremely low. A microbe from Europa would have evolved for billions of years in a totally dark, cold, high-pressure, non-oxygen environment. It would not be adapted to the warm, bright, oxygen-rich conditions on Earth. It would have no natural way to infect humans, which it has never encountered. However, because the risk is not zero, any sample returned to Earth would be handled with extreme caution in a maximum-security containment lab.
What is the difference between life and intelligent life?
When scientists search for life on Europa, they are looking for any form of life, which most likely means simple, single-celled organisms like bacteria. This is biological life. Intelligent life, or “sentient life,” is what we see in science fiction: a complex, thinking civilization that can communicate or build technology. There is currently no evidence to suggest intelligent life exists on Europa. The search for intelligent life is separate and is often done by listening for radio signals from distant stars.