Europa
Up Close
An in-depth look at Jupiter’s icy moon and Europa Clipper’s plans for investigation.
SCROLL TO CONTINUE
Jupiter’s moon Europa shows strong evidence for an ocean of liquid water beneath its icy crust. In fact, it could have all the ingredients needed for life as we know it.
NASA’s Europa Clipper spacecraft will perform dozens of close flybys of Europa. Europa Clipper’s main science goal is to determine whether there are places below the surface of Jupiter’s icy moon, Europa, that could support life. The mission’s detailed exploration of Europa will help scientists better understand the astrobiological potential for habitable worlds beyond our planet.
To accomplish this, an intricate array of instruments will work together to gather measurements of the internal ocean, map the surface composition and geology, and hunt for plumes of water vapor that may be venting from the icy crust.
Here’s how…
To accomplish this, an intricate array of instruments will work together to gather measurements of the internal ocean, map the surface composition and geology, and hunt for plumes of water vapor that may be venting from the icy crust.
Here’s how…
Magnetosphere
One of the most important measurements made by the Galileo mission, which previously explored Europa, showed how Jupiter's magnetic field was disrupted in the space around Europa. The measurement strongly implied that a special type of magnetic field is created (induced) within Europa by a deep layer of some electrically conductive fluid (like saltwater) beneath the surface, which interacts with Jupiter’s strong magnetic field. Europa Clipper will study this induced magnetic field.
Atmosphere

Europa has an extremely thin oxygen atmosphere, with barely 100 billionth of Earth’s atmospheric pressure. Despite this, there is a lot of activity in Europa’s thin atmosphere. Researchers using the Hubble Space Telescope and other observatories found evidence that Europa might be actively venting water into space, which would mean the moon is geologically active today. Other gases might also be leaking out of the subsurface, and dust particles are blasted off of Europa by micrometeorites. The Europa Clipper spacecraft will search for any such water plumes and study other properties of the moon’s atmosphere, including how it interacts with Jupiter.
Surface
Europa’s water-ice surface is the smoothest of any solid body in the solar system, but is far from featureless. It has a relatively small number of craters, and appears to be no more than 40 to 90 million years old, which is youthful in geologic terms.
As Europa orbits Jupiter it experiences strong tidal forces — somewhat like the tides in Earth’s oceans caused by our Moon — that cause its icy outer shell to flex. That flexing leads to intricate patterns of linear cracks, ridges, bands, pits, and domes that cover much of its surface.
As Europa orbits Jupiter it experiences strong tidal forces — somewhat like the tides in Earth’s oceans caused by our Moon — that cause its icy outer shell to flex. That flexing leads to intricate patterns of linear cracks, ridges, bands, pits, and domes that cover much of its surface.
Scientists will use Europa Clipper’s visible-light cameras to map Europa at far better resolution than previous missions. Scientists will also use Europa Clipper’s instruments to map far more of the moon’s surface, including its composition, temperature, and roughness. Combined, these investigations will reveal much about Europa’s chemistry and geologic activity.

Instruction
Tap a plus icon above or click the arrows below to continue.
Instruction
Tap a plus icon above or click the arrows below to continue.
Instruction
Tap a plus icon above or click the arrows below to continue.
Instruction
Tap a plus icon above or click the arrows below to continue.
0of4
Instruction
Tap a plus icon above or click the arrows below to continue.
Ice Shell

Scientists are unsure of the thickness of Europa’s outer icy shell, with many estimates ranging from approximately 10 to 15 miles (15 to 25 kilometers) thick. The ice shell sits atop a salty ocean of liquid water. Unlike Earth’s rocky crust, Europa’s surface is almost entirely thick water ice with a small fraction of salty material and perhaps organic chemicals mixed in. If Europa’s exterior is being deformed by forces acting on its ice shell (what scientists refer to as being “tectonically active”), then ocean material may be able to reach the moon’s surface and surface material may be moving into the ocean. Scientists will use Europa Clipper’s instruments to measure the ice shell’s thickness, analyze its structure, and search for warmer regions where liquid water may be near the surface or might have erupted onto the surface.
Ocean
Several independent lines of evidence have led scientists to conclude that Europa almost certainly has a global ocean of salty liquid water beneath its icy crust. The ocean is thin relative to the moon’s overall size, but it is thought to be 40 to 100 miles (60 to 150 kilometers) deep – which means it contains more than twice as much water as all of Earth’s oceans combined.
Returning data confirming that Europa’s ocean exists, and measuring its depth and salinity, is among Europa Clipper’s most important objectives.
Returning data confirming that Europa’s ocean exists, and measuring its depth and salinity, is among Europa Clipper’s most important objectives.
Rocky Interior & Iron-Rich Core
Europa’s rocky interior lies between the ocean layer and the moon’s core. Its exact diameter is not precisely known. As Europa flexes due to the gravity of Jupiter, ocean water might seep into the uppermost portion of the rocky layer to be heated and interact chemically with the rock, loading the water with minerals and organic (carbon-containing) compounds as it flows back into the bottom of the ocean through cracks, fissures, or hydrothermal vents. Such a process could supply the ocean with building blocks for life, and with materials that could serve as food for simple organisms.
The exact size and composition of Europa’s metallic core is unknown, but measurements of Europa's gravity and composition from the Europa Clipper mission should help scientists home in on its diameter.
The exact size and composition of Europa’s metallic core is unknown, but measurements of Europa's gravity and composition from the Europa Clipper mission should help scientists home in on its diameter.
Loading
100