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

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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…

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.

INSTRUMENT HIGHLIGHTS

Europa Clipper Magnetometer (ECM) ›

ECM will study Europa’s magnetic field and how it interacts with Jupiter’s magnetic field. By studying this relationship, researchers can better understand the nature of Europa’s ocean.

Plasma Instrument for Magnetic Sounding (PIMS) ›

PIMS will be used to detect distortions in Europa’s induced magnetic field caused by space plasma trapped in Jupiter’s magnetic field. PIMS will help researchers distinguish between the distortions caused by space plasma from the distortions caused by Europa’s saltwater ocean.

Atmosphere

These composite images show a suspected plume of material erupting two years apart from the same location on Jupiter's icy moon 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's Space Telescope Imaging Spectrograph, were seen in silhouette as the moon passed in front of Jupiter. Credit: 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.

INSTRUMENT HIGHLIGHTS

MAss SPectrometer for Planetary EXploration/Europa (MASPEX) ›

MASPEX will analyze gases in Europa’s faint atmosphere and possible plumes.

SUrface Dust Analyzer (SUDA) ›

SUDA will be used to identify the chemistry and area of origin of materials that might be vented into space as plumes or blasted into space by surface impacts, offering clues to Europa’s ocean salinity and composition.

Europa Ultraviolet Spectrograph (Europa-UVS) ›

Europa-UVS will collect ultraviolet light with a telescope to create images that will help determine the composition of Europa’s atmospheric gases and surface materials. It will also search near Europa for signs of plume activity.

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.

INSTRUMENT HIGHLIGHTS

Europa Imaging System (EIS) ›

EIS will employ a wide-angle camera and a narrow-angle camera to produce high-resolution color and stereoscopic images of Europa, reveal geologic activity, measure surface elevations, and provide context for other instruments.

Europa Thermal Imaging System (E-THEMIS) ›

E-THEMIS will obtain heat measurements to help scientists identify warmer regions on Europa, where warm liquid water may be near the surface or might have erupted onto the surface, and measure surface texture to understand small-scale properties of the surface.

Mapping Imaging Spectrometer for Europa (MISE) ›

MISE will be used to map the distribution of ices, salts, and organics helping scientists understand the moon’s geologic history and help determine if Europa’s suspected ocean is suitable for life.

Surface

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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 believe 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. Credit: 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.

INSTRUMENT HIGHLIGHTS

Radar for Europa Assessment and Sounding: Ocean to Near-surface (REASON) ›

REASON will be used to probe Europa’s icy shell for water and estimate the depth to the moon’s suspected ocean, as well as study the ice’s structure and thickness.

Gravity/Radio Science ›

Gravity/Radio Science: Measuring Europa’s gravity at various points in the moon’s orbit will show how Europa flexes and how the Europa Clipper spacecraft’s trajectory is changed by Europa’s gravitational field, helping reveal its internal structure, including the thickness of its ice shell.

Europa Clipper Magnetometer ›

ECM data will be used to determine the depth to the salty ocean and thus the thickness of Europa’s icy crust, based on the moon’s induced magnetic field characteristics.

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.

INSTRUMENT HIGHLIGHTS

Europa Clipper Magnetometer (ECM) ›

ECM will help confirm that Europa’s ocean exists and measure its depth and salinity, based on the moon’s induced magnetic field strength.

Plasma Instrument for Magnetic Sounding (PIMS) ›

PIMS will be used detect distortions in Europa’s induced magnetic field caused by space plasma trapped in Jupiter’s magnetic field. PIMS will help researches distinguish between the distortions caused by space plamsa from the distortions caused by Europa’s salt water ocean.

Gravity/Radio Science ›

Europa Clipper will measure Europa’s gravity field at various points in the moon’s orbit to show how Europa flexes and help reveal Europa’s internal structure.

SUrface Dust Analyzer (SUDA) ›

SUDA will identify the chemistry of materials that are ejected from Europa and which might be vented into space as plumes, offering clues to Europa’s ocean salinity.

MAss SPectrometer for Planetary EXploration/Europa (MASPEX) ›

MASPEX will study the chemistry of material derived from the moon’s suspected subsurface ocean and how the ocean and surface exchange material.

Mapping Imaging Spectrometer for Europa (MISE) ›

MISE will be used to map the distribution of ices, salts, and organics helping scientists understand the moon’s geologic history and help determine if Europa’s suspected ocean is suitable for life.

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.

INSTRUMENT HIGHLIGHTS

Gravity/Radio Science ›

Measuring Europa’s gravity at various points in the moon’s orbit will show how Europa flexes and how the Europa Clipper spacecraft’s trajectory is changed by Europa’s gravitational field, helping reveal its internal structure.

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