In our solar system, there is a special moon orbiting the giant planet Jupiter. This moon, called Europa, is an exciting place for scientists. From the outside, Europa looks like a bright, white-and-reddish ball of ice, covered in long cracks and streaks. But what makes it truly special is not what we see on the surface, but what we are almost certain is hidden below: a giant, global ocean of liquid saltwater. This ocean is believed to be miles deep and could contain more than twice as much water as all of Earth’s oceans combined.
Wherever we find liquid water on Earth, we find life. This simple fact is why Europa is one of the most promising places to look for life beyond our planet. But this ocean is protected by an ice shell that is probably many miles thick. We cannot just land and drill down to take a look. To solve this amazing puzzle, NASA has sent a special robotic explorer on a long journey. This mission is called Europa Clipper, and it launched from Earth in October 2024. It is now on its way to the Jupiter system.
The Europa Clipper spacecraft is a flying laboratory, packed with the most advanced science tools ever sent to an outer moon. It will not land on Europa, and it will not even orbit Europa directly. Instead, it will orbit Jupiter and make dozens of close, fast flybys of Europa, some as low as 16 miles above the surface. Its main job is to investigate this mysterious ocean from afar. But if the ocean is hidden under miles of ice, how can the spacecraft possibly find out what’s inside?
What Is the Main Goal of the Europa Clipper Mission?
The most important thing to know about the Europa Clipper mission is its main goal. The mission is not designed to find life itself. You might see headlines that say “NASA is looking for aliens on Europa,” but that is not quite right. Europa Clipper does not have a microscope to look for tiny creatures or a shovel to dig for fossils. Its mission is to answer a different, but equally important, question: Is Europa habitable? “Habitable” is a word scientists use that simply means “Does this place have the right conditions for life to exist?” Think of it thisall as a detective mission. Before you can look for a suspect, you first have to find out if the location is even a place where a suspect could live.
Scientists believe that life as we know it needs three key “ingredients” to get started and survive. Europa Clipper’s job is to fly by the moon and check if all three of these ingredients are present in its ocean. These three ingredients are:
- Liquid Water: We are almost positive Europa has this. The mission will confirm it and learn more about it.
- Chemistry: Life needs certain chemical building blocks. These are elements like carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur. Life uses these to build things like DNA and proteins.
- Energy: All life needs a source of energy to move, grow, and eat. On Earth, most life gets energy from the Sun. Under miles of ice, life would need a different energy source, perhaps from chemicals.
So, Europa Clipper is a habitability investigation. It is the first major step. It will fly past the moon again and again, gathering clues with its powerful instruments. It will try to figure out if that hidden ocean has water, the right chemicals, and a source of energy, all in one place. If it finds all three, it will tell us that Europa is one of the best places in the solar system to send a future mission, one that would be designed to actually look for life.
How Will Clipper Prove the Ocean Is Really There?
We are very, very sure the ocean exists, but science loves proof. The first clues came from NASA’s Galileo mission in the 1990s, which saw how Europa’s surface was cracked and moving, like ice floating on water. It also took magnetic readings. Europa Clipper will follow up on this with an extremely powerful instrument called a magnetometer. This tool is basically a super sensitive compass, but it is not looking for Europa’s north or south pole. It is looking for a “second” magnetic field that proves a liquid ocean is hiding below the ice.
Here is how it works: Jupiter, the giant planet Europa orbits, has the most powerful magnetic field in the solar system. This field is huge and it washes over Europa constantly. If Europa were just a solid ball of ice and rock, Jupiter’s magnetic field would pass through it in a very simple, predictable way. But scientists believe Europa has a global ocean of saltwater. Salty water is a great conductor of electricity, much like a wire. When Jupiter’s magnetic field moves through this conducting, salty ocean, it creates a new magnetic field inside Europa. This is called an “induced magnetic field.”
As Europa Clipper flies past the moon, its magnetometer will measure this weak, induced magnetic field. By measuring the strength and direction of this “second” field, scientists can confirm beyond any doubt that the ocean is real, that it is global (meaning it covers the whole moon), and that it is made of saltwater. Even more, the data will help them figure out two amazing details: how deep the ocean is (it could be 40 to 100 miles deep) and how salty it is. Knowing the saltiness is a key clue to understanding the ocean’s chemistry and how it interacts with the rocky seafloor below.
How Will the Mission Measure the Thickness of the Ice?
This is one of the biggest questions about Europa. Is the ice shell a few miles thick, or is it 20 miles thick? The answer changes everything. A thinner shell means it is easier for things to move between the ocean and the surface. It would be easier for warm water from below to rise up, and for useful chemicals from the surface to get mixed down into the ocean. It would also make it easier for a future mission to one day drill through. A very thick shell would make all of this much harder. To find the answer, Europa Clipper is carrying a special instrument that can see through the ice: a radar.
This instrument is called REASON, which stands for Radar for Europa Assessment and Sounding: Ocean to Near-surface. It works very much like a “fish finder” on a boat or the radar an airplane uses to measure the ground below it. As Clipper flies over Europa, the REASON instrument will send out radio waves. These waves are special; they are at a frequency that can travel right through ice but will bounce off liquid water. The radio signal will shoot down, pass through the miles of ice, and then hit the top of the hidden ocean.
When the signal hits the water, a strong echo will bounce back up to the spacecraft. The instrument will measure the tiny amount of time it takes for that echo to return. By doing this over and over again, all across the moon, scientists will be able to build the first-ever 3D map of the ice shell. They will finally know exactly how thick the ice is in different places. This radar is so good that it will also look for other amazing features. It might be able to spot “lakes” or pockets of liquid water inside the ice shell, not just below it. These “perched” lakes, if they exist, would be incredibly exciting, as they are closer to the surface and might be a place where ocean water gets trapped.
What Chemical Building Blocks Is Clipper Looking For?
This is where the second ingredient for life comes in: chemistry. Life on Earth is built from a few key elements, which scientists sometimes call CHNOPS. This stands for Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, and Sulfur. These are the basic, non-negotiable building blocks for all life we know. They are what make up DNA, proteins, fats, and sugars. If Europa’s ocean is just pure, sterile water, it is not a very good place for life. But if it is a rich chemical soup, full of these building blocks, then it is a much more promising environment.
But how can Clipper find these chemicals if they are locked in an ocean miles below? It will do this by studying the surface. The surface of Europa is not clean, white ice. It is covered in long, dark, reddish-brown streaks and splotches. These messy areas are called “chaos terrain.” Scientists are very excited about this “gunk.” They believe this is material from the ocean below that has, over millions of years, been pushed up onto the surface. Perhaps it seeped through cracks in the ice or was erupted in a cryovolcano (a cold, ice volcano). Once this ocean material is on the surface, it gets blasted by radiation from Jupiter, which “cooks” it and turns it that reddish-brown color.
Europa Clipper has a set of powerful “magic glasses” called spectrometers. These instruments look at the light that is reflected off the surface. Every chemical and mineral reflects light in a unique way, like a “fingerprint.” The spectrometer (called MISE) will map these reddish areas and read their chemical fingerprints. It will be able to tell scientists what they are made of. Are they just simple salts, like table salt? Or are they something more exciting, like sulfur compounds (which could be a sign of energy) or, most exciting of all, complex carbon-based molecules known as “organics”? Finding organic molecules in these streaks would be a huge clue that the ocean contains the building blocks for life.
Where Could Life Get Energy From Deep Under the Ice?
This brings us to the third and most difficult ingredient: energy. On Earth, the entire food web is based on energy from the Sun. Plants use sunlight for photosynthesis, animals eat the plants, and so on. This cannot happen on Europa. The ocean is trapped in total darkness, under an ice shell so thick that no sunlight could ever reach it. So, if life exists there, it must be using a different kindof energy source. Europa Clipper is designed to look for signs of two possible energy sources.
The first source of energy comes from inside Europa. Europa is constantly being squeezed and stretched by Jupiter’s massive gravity, and by the pull of the other large moons, Io and Ganymede. This constant gravitational tug-of-war is called “tidal flexing.” It is like bending a paperclip back and forth—it generates heat. This tidal heat is what keeps Europa’s ocean liquid in the first place. But it could also do more. It likely heats up the rocky core of the moon, enough to create volcanic activity on the ocean floor. We are not talking about volcanoes of lava, but “hydrothermal vents.” These are hot springs on the seafloor that gush out hot, mineral-rich water. On Earth’s ocean floors, entire ecosystems of bacteria, crabs, and tube worms thrive in total darkness by “eating” the chemicals from these vents. This is called chemosynthesis. Clipper will look for the chemical byproducts of these vents, such as hydrogen or methane, which might be mixed into the ice.
The second energy source comes from outside Europa. The moon’s surface is being blasted by intense radiation from Jupiter. This radiation is deadly on the surface, but it creates a powerful chemical reaction. It breaks apart water molecules (H2O) in the ice and creates new, highly reactive chemicals, like oxygen and hydrogen peroxide. These chemicals are a potent form of chemical energy. If these surface chemicals can find a way to get mixed down into the ocean—perhaps by the same cracks that bring ocean water up—they could provide a powerful source of “food” for any potential microbes. Clipper’s instruments will study the surface chemistry to see just how much of this “radiation food” is being created.
What Are the Water Plumes and Why Are They So Important?
This is perhaps the most exciting part of the mission. For years, scientists using the Hubble Space Telescope have seen faint hints that Europa might be shooting giant geysers of water vapor into space, much like Saturn’s moon Enceladus, which is famous for its plumes. These plumes, if they are real and active, are a total game-changer for the mission. Why? Because they are a free sample of the ocean, delivered directly to the spacecraft. Instead of having to figure out how to drill down miles, all Clipper has to do is fly through one of these geysers.
This is the main job for two of Clipper’s most important instruments: a dust analyzer (SUDA) and a mass spectrometer (MASPEX). These instruments are, in simple terms, “plume sniffers.” They are designed to “taste” the environment around Europa. As Clipper makes its high-speed flybys, these instruments will be wide open, ready to catch anything that hits them. If the spacecraft flies through a plume, SUDA will catch tiny ice grains and dust particles. It will instantly analyze them and tell scientists what they are made of—are they salty? Do they contain organic molecules?
At the same time, MASPEX will “sniff” the gases in the plume, identifying molecules like water vapor, carbon dioxide, or methane. Flying through a plume is the most direct way to sample the ocean. It is the mission’s best chance to find out, with certainty, what chemicals are in that dark, hidden ocean. Even if the plumes are small or not very frequent, Clipper’s instruments are so sensitive that they will analyze the tiny, tiny particles that are constantly being kicked up from Europa’s surface by micrometeorite impacts. These particles are also a sample of the surface, and by “tasting” them, Clipper can learn about the chemistry of the ice.
Will Europa Clipper Be Able to Find Actual Life?
This is the question everyone wants to know, and it is important to be very clear about the answer: No, Europa Clipper will not find life. The spacecraft is not designed for that job. It does not have a microscope to see a microbe, and it is not a lander that can scoop up a sample and put it in a test tube. Finding life, especially microscopic life, is an incredibly difficult thing to do. We have not even been able to confirm it on Mars, where our rovers are on the ground. The goal of Europa Clipper is to be a reconnaissance mission. It is the essential first step that we must take before we can even think about looking for life.
Think of it this way: Europa Clipper is like a scout sent to map an unknown island. The scout’s job is not to find a person. The scout’s job is to fly over the island and report back: “Yes, there is fresh water. Yes, there are fruit trees. Yes, there is shelter. This island is habitable.” Based on that report, a second mission would be planned—a “boots on the ground” mission—to actually land and look for the inhabitants.
That is exactly what Europa Clipper is doing for Europa. Its job is to fly by and check for the three ingredients: the water, the chemistry, and the energy. If it returns data that says, “Yes, the ocean is salty and deep. Yes, the ice is thin in some places. And yes, we have found organic molecules and signs of energy,” it will have been a 100 percent successful mission. It will have proven that Europa is a habitable world. And it will give scientists all the information they need to design that next, even more exciting mission—perhaps a lander or a robotic drill—that will finally take on the grand challenge of answering the ultimate question: “Are we alone?”
Conclusion
NASA’s Europa Clipper mission, which is already on its long voyage to Jupiter, is one of the most exciting science missions of our lifetime. It will arrive in the Jupiter system in 2030 and begin a detailed investigation of the icy moon Europa. Its purpose is not to find life, but to find out if Europa has the conditions for life. It is looking for the three key ingredients: liquid water, the right chemical building blocks, and a source of energy.
To do this, it will use a powerful ice-penetrating radar to measure the ice shell, a sensitive magnetometer to prove the ocean is salty and deep, and special cameras and spectrometers to analyze the “red gunk” on the surface. The mission’s biggest prize would be to fly through a water plume, giving it a direct “taste” of the ocean’s chemistry. Europa Clipper will paint the most detailed picture we have ever had of this mysterious ocean world, and its findings will tell us where to look next in our search to understand life in the universe.
If Clipper’s data shows that Europa has all the right ingredients, what kind of mission do you think we should send next?
FAQs – People Also Ask
When will Europa Clipper get to Jupiter?
NASA’s Europa Clipper spacecraft launched in October 2024. After a long journey that includes gravity assists from Mars and Earth, it is scheduled to arrive in the Jupiter system in April 2030.
Will Europa Clipper land on the ice?
No, Europa Clipper is not a lander. It is a large spacecraft that will orbit Jupiter and perform approximately 50 close, high-speed flybys of Europa to gather data from a safe distance.
Why is the mission orbiting Jupiter and not Europa?
Europa is located deep inside Jupiter’s powerful radiation belts. This radiation is extremely intense and can damage spacecraft electronics. By orbiting Jupiter and making quick flybys of Europa, the spacecraft spends most of its time outside the most dangerous radiation zones, allowing it to survive much longer.
What is the “red stuff” on Europa’s surface?
Scientists believe the reddish-brown streaks and patches on Europa’s ice are a mixture of salts and sulfur compounds. It is thought that this material came from the saltwater ocean below and was brought to the surface through cracks, where it was then “cooked” by Jupiter’s intense radiation.
Is Europa’s ocean freshwater?
No, scientists are almost certain the ocean is saltwater. The magnetometer on the Galileo spacecraft gave strong evidence that the ocean is salty because it conducts electricity. Europa Clipper’s new magnetometer will measure exactly how salty the ocean is.
How big is Europa’s ocean?
The ocean on Europa is believed to be global, meaning it covers the entire moon underneath the ice shell. It is estimated to be between 40 and 100 miles (60 to 150 kilometers) deep, which means it could contain more than twice as much water as all of Earth’s oceans combined.
How cold is Europa?
The surface of Europa is extremely cold. Temperatures at the equator only reach about minus 260 degrees Fahrenheit (minus 160 degrees Celsius). At the poles, it gets even colder, down to minus 370 degrees Fahrenheit (minus 220 degrees Celsius).
Has NASA sent a mission to Europa before?
NASA’s Galileo spacecraft, which orbited Jupiter from 1995 to 2003, gave us our first detailed look at Europa and provided the first strong evidence for its subsurface ocean. However, Europa Clipper is the first NASA mission designed specifically to study Europa in detail.
What is the difference between Europa and Enceladus?
Both Europa (a moon of Jupiter) and Enceladus (a moon of Saturn) are icy moons with liquid water oceans under their crusts. The main differences are size and activity. Europa is much larger, about the size of Earth’s moon. Enceladus is tiny, but it is famous for its giant water plumes that constantly spray into space. Europa may have plumes, but they appear to be less frequent.
What happens to Europa Clipper at the end of its mission?
After it completes its science mission, NASA will intentionally dispose of the spacecraft. To protect the possibly habitable ocean of Europa from any contamination, the spacecraft will be sent on a final crash course, likely into one of Jupiter’s other large moons, Ganymede, or into Jupiter itself.