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Europa Up Close

An in-depth look at Jupiter's icy moon, and Europa Clipper's plans for investigation.

An illustration of Europa Clipper in front of Europa.

  • Evidence of an Ocean

    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.

    This artist's concept depicts NASA's Europa Clipper spacecraft as it orbits Jupiter and passes over the gas giant's ice-covered moon Europa. Scheduled to arrive at Jupiter in April 2030, the mission will be the first to specifically target Europa for detailed science investigation.
    An artist's concept of Europa Clipper flying above Europa's icy surface.
    NASA

  • Europa Clipper Will Make Multiple Flybys

    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 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 that may be venting from the icy crust.

    The Europa Clipper spacecraft, the largest NASA has ever built for a mission to the outer solar system.
    NASA/JPL-Caltech

  • 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.

    illustration of spacecraft at europa with jupiter in background
    An artist’s concept of Jupiter and Europa (in the foreground) with the Galileo spacecraft after its pass through a plume erupting from Europa’s surface.
    NASA/JPL-Caltech/Univ. of Michigan

Atmosphere

Hubble Sees Recurring Plume Erupting From Europa
These composite images show a suspected plume of material erupting two years apart from the same location on Europa. The images bolster evidence that the plumes are a real phenomenon, flaring up intermittently in the same region on the satellite. Both plumes, photographed in ultraviolet light by NASA's Hubble Space Telescope Imaging Spectrograph, were seen in silhouette as the moon passed in front of Jupiter.
NASA

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.

    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.

The largest portion of the Europa's surface can be seen at the highest resolution from Galileo.
The puzzling, fascinating surface of Jupiter's icy moon Europa looms large in this newly-reprocessed color view, made from images taken by NASA's Galileo spacecraft in the late 1990s. This is the color view of Europa from Galileo that shows the largest portion of the moon's surface at the highest resolution. The view was previously released as a mosaic with lower resolution and strongly enhanced color (see PIA02590). To create this new version, the images were assembled into a realistic color view of the surface that approximates how Europa would appear to the human eye. The scene shows the stunning diversity of Europa's surface geology. Long, linear cracks and ridges crisscross the surface, interrupted by regions of disrupted terrain where the surface ice crust has been broken up and re-frozen into new patterns. Color variations across the surface are associated with differences in geologic feature type and location. For example, areas that appear blue or white contain relatively pure water ice, while reddish and brownish areas include non-ice components in higher concentrations. The polar regions, visible at the left and right of this view, are noticeably bluer than the more equatorial latitudes, which look more white. This color variation is thought to be due to differences in ice grain size in the two locations. Images taken through near-infrared, green and violet filters have been combined to produce this view. The images have been corrected for light scattered outside of the image, to provide a color correction that is calibrated by wavelength. Gaps in the images have been filled with simulated color based on the color of nearby surface areas with similar terrain types. This global color view consists of images acquired by the Galileo Solid-State Imaging (SSI) experiment on the spacecraft's first and fourteenth orbits through the Jupiter system, in 1995 and 1998, respectively. Image scale is 1 mile (1.6 kilometers) per pixel. North on Europa is at right.
NASA/JPL-Caltech/SETI Institute

Ice Shell

This graphic shows Europa’s icy shell, with many estimates ranging from approximately 10 to 15 miles (15 to 25 kilometers) thick. Researchers think that tidal heating impacts the layer between the ice and the ocean, and that some of the heat might be transferred through the ice layer to the surface through convection. This causes disrupted surface features. There could also potentially be plumes venting material from Europa’s surface.
NASA

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.

Inside Europa

  • 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.

  • 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.

A side view of what Europa what look like if we could slice into it. There's beige, and white crust with reddish streaks and plumes erupting. Below the crust is a blue ocean on top of a brown crust with a reddish hotspot in the lower left corner.
Scientists think that under the icy surface of Jupiter's moon Europa a saltwater ocean exists that may contain more than twice as much liquid water as all of Earth's oceans combined. This artist's concept (not to scale) depicts what Europa's internal structure could look like: an outer shell of ice, perhaps with plumes of material venting from beneath the surface; a deep, global layer of liquid water; and a rocky interior, potentially with hydrothermal vents on the seafloor.
NASA/JPL-Caltech
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