With an equatorial diameter of 1,940 miles (3,100 kilometers), Europa is about 90 percent the size of Earth’s Moon.

Europa is the smallest of the four largest moons orbiting Jupiter (including Io, Ganymede, and Callisto), and the sixth-closest to the planet of all the 79 moons of Jupiter. Slightly smaller than Earth's Moon, Europa is primarily made of silicate rock and has a water-ice crust and probably an iron-nickel core. It has a very thin atmosphere, composed primarily of oxygen. Its surface is striated by cracks and streaks, but craters are relatively few. Scientists are almost certain that hidden beneath the icy surface of Europa is a saltwater ocean containing about twice as much water as Earth’s global ocean. It may be the most promising place in our solar system to find present-day environments suitable for some form of life beyond Earth. Learn more about Europa here. 

Europa was discovered in 1610 by Galileo Galilei. The German astronomer Simon Marius claimed to have observed Jupiter's moons at about the same time as Galileo, and is commonly credited as being the co-discoverer of the moons. The moon was named after Europa, the Phoenician mother of King Minos of Crete, with whom Zeus (the Greek equivalent of the Roman god Jupiter) fell in love. In addition to Earth-bound telescope observations, Europa has been examined by a succession of space-probe flybys, the first occurring in the early 1970s. Learn more about the history of discovering and exploring Europa here. 

Europa is considered one of the most promising currently habitable environments in our solar system. 

Europa could have all the “ingredients” needed for life as we know it. 

• Water: Evidence suggests there is a global ocean over twice the volume of Earth’s oceans combined. 
• Organics: Scientists believe it's likely that the essential chemical building blocks for life exist on Europa, stemming from the moon’s formation and from asteroid and comet impacts. 
• Energy: Scientists believe Europa may have the chemical energy sources needed for life. This includes surface radiation from Jupiter and potential interactions between water and a rocky seafloor. 
• Stability: Europa’s ocean may have existed for the entirety of our solar system’s history, approximately 4 billion years. 

Learn more about Europa’s ingredients for life here.

Below Europa’s icy surface, evidence suggests there is a global ocean over twice the volume of Earth’s oceans combined. 

Learn more about the evidence for an ocean at Europa here.

Europa shows strong evidence for an ocean of liquid water beneath its icy crust. Images from the Voyager 2 spacecraft showed features indicating that Europa’s surface had been active in the recent past. A bright, icy surface that lacked large impact craters implied the moon’s surface was young, meaning something had erased them. The Galileo spacecraft later saw additional features that suggested activity related to water (or possibly warm ice) beneath the surface, including areas of jumbled blocks of displaced ice ("chaos terrain"), and features like spots, domes, and pits. Galileo also showed how Jupiter’s magnetic field was disrupted in the space around Europa. This measurement strongly implies that a magnetic field is being created within Europa by an electrically conductive fluid beneath the surface. And based on Europa's icy composition, scientists think the most likely material to create this magnetic signature is a global ocean of salty water.

Theory and observation indicate that Europa's icy shell is around 15 to 25 kilometers (10 to 15 miles) thick, overlying an ocean approximately 60-150 kilometers (40 to 100 miles) deep.

Most of Europa's surface consists of bright water ice. The moon has reddish non-ice material along cracks and within areas where the surface has been disrupted. Europa's visible surface is only about 65 million years old on average, so some sort of geologic activity must have removed older features. Temperatures range from as high as approximately 140 Kelvin (about -210 degrees Fahrenheit) in dark material at the moon's equator to as low as approximately 50 Kelvin (-370 degrees Fahrenheit) in bright icy patches at the moon's poles. 

Learn more about Europa here. 

Europa orbits Jupiter at about 417,000 miles (671,000 kilometers) from the planet, which itself orbits the Sun at a distance of roughly 500 million miles (780 million kilometers), or 5.2 astronomical units (AU). One AU is the distance from Earth to the Sun.

NASA's Europa Clipper spacecraft will conduct a detailed survey of Jupiter's moon Europa to determine whether there are places below the surface that could support life. The spacecraft, in orbit around Jupiter, will make about 40 to 50 close passes over Europa, shifting its flight path for each flyby to soar over a different location so that it eventually scans nearly the entire moon. Learn more about the mission here. 

NASA's Europa Clipper spacecraft will perform dozens of close flybys of Europa, gathering detailed measurements to investigate whether the moon could have conditions suitable for life. Europa Clipper is not a life detection mission – its main science goal is to determine whether there are places below Europa’s surface that could support life.

During the prime mission, the spacecraft will perform approximately 50 flybys of Europa at closest-approach altitudes as low as 16 miles (25 kilometers) above the surface.

The Europa Clipper mission will launch in October 2024.

The Europa Clipper mission will launch in October 2024 and will arrive in 2030. The mission is currently planned to conduct four years of science observations at Europa.

Jupiter’s moon Europa shows strong evidence of an ocean of liquid water beneath its icy crust. Beyond Earth, Jupiter’s moon Europa is considered one of the most promising currently habitable environments in our solar system. Below Europa’s icy surface, evidence suggests there is a global ocean over twice the volume of Earth’s oceans combined.

Europa Clipper, with its massive solar arrays and radar antennas, is the largest spacecraft NASA has ever developed for a planetary mission. With its arrays deployed, the spacecraft spans more than 100 feet (30.5 meters). Learn more about the spacecraft here.

The spacecraft has a dry mass (no propellant in the tanks) of 7,145 pounds (3241 kg). Learn more about the spacecraft here. 

The spacecraft will use giant solar arrays for its power source. The spacecraft needs large solar arrays to collect enough light for its power needs as it operates in the Jupiter system, which is more than five times as far from the Sun as Earth. Learn more about the spacecraft here.

NASA will communicate with the Europa Clipper spacecraft using the Deep Space Network, an international array of giant radio antennas that supports interplanetary spacecraft missions. The spacecraft will receive signals from the Deep Space Network, execute commands, and send scientific data back to Earth using its high-gain antenna. Learn more about the spacecraft here. 

The science includes gathering measurements of the internal ocean, mapping the surface composition and geology, and hunting for plumes of water vapor that may be venting from the icy crust. Learn more about the mission’s science objectives here.

NASA has selected nine science instruments for the mission. The selected payload includes cameras and spectrometers to produce high-resolution images of Europa's surface and determine its composition. An ice-penetrating radar will search for subsurface lakes similar to those beneath Antarctica's ice sheet. The mission will also carry a magnetometer and a plasma instrument to measure the strength and direction of the moon's induced magnetic field, which will allow scientists to confirm the existence of Europa’s subsurface ocean and determine its characteristics (e.g., depth and salinity). Contributions from multiple instruments will help constrain ice shell thickness. A thermal instrument will survey Europa's frozen surface in search of recent eruptions of warmer water at or near the surface. Additional instruments will characterize the composition of gases and tiny particles in the moon's thin atmosphere – and search for potential plumes of water vapor that might erupt from the moon’s surface. Learn more about the spacecraft’s instruments here.

Europa Clipper is not a life detection mission – its main science goal is to determine whether there are places below Europa’s surface that could support life.

Europa Clipper’s discoveries at Europa will help us better understand many aspects of Earth. For example, Europa is one of the only places beyond Earth where we have found plate tectonics, the motion of portions of the surface crust scientists believe are driven by the fluid-like motions of warm solid layers like the Earth’s mantle and Europa’s icy shell.  Studying this motion, called convection, may be easier on Europa since the surface ice layer is much thinner than Earth’s rocky crust. Europa’s young surface, which lacks many sources of terrestrial erosion such as wind and water, allows us to view the results of tectonic activity in a pristine form. In addition, looking for life in other places beyond Earth is a way to help us learn more about how life originated on Earth. Since Earth’s plate tectonics may help maintain chemical imbalances that can support life, studying a similar process on Europa could help us understand life on Earth and beyond. 

NASA has selected a SpaceX Falcon Heavy as the launch vehicle for the Europa Clipper mission. The launch vehicle selection was announced in July 2021. Utilizing this vehicle, the mission is targeting a launch in October 2024 on a Mars-Earth Gravity Assist (MEGA) trajectory that will arrive at Jupiter in April 2030.

Jupiter is five times as far away from the Sun as Earth. The Europa Clipper mission will launch in October 2024 and will arrive in 2030, after a five and half year journey.

Europa Clipper’s orbit around Jupiter is preferable due to the belts of intense  radiation that surround the planet, which can damage electronics. Initial mission concept studies, which led to the Europa Clipper mission, showed that a spacecraft orbiting Europa might only be able to survive for months, while a Jupiter-orbiting mission should have a multi-year lifetime. The innovative design of the Europa Clipper trajectory allows about 50 flybys of Europa, each with a different close approach location, to allow almost the complete moon to be mapped at high resolution. After each close approach, the spacecraft travels outside of Jupiter’s radiation belts to downlink data, uplink new commands, and prepare for the next flyby.