When Europa Clipper launches in 2024, it will set out to answer a key question: Are there environments on Europa capable of supporting life?
To accomplish this, an intricate array of instruments will work in concert 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 are ten things to know about how Europa Clipper’s instruments will achieve the mission’s science objectives.
1. Cameras will produce high-resolution images of Europa's surface.
Europa Clipper’s imaging system will capture Europa’s ridges, valleys, bands, and other surface features in unprecedented detail. The imaging system has a wide-angle camera and a narrow-angle camera. Each camera has an eight-megapixel sensor sensitive to visible wavelengths of light and a small range of near-infrared and ultraviolet wavelengths. The imaging system will map about 90 percent of Europa at 330 feet (100 meters) per pixel. That’s six times more of Europa’s surface than was mapped by images from the Galileo spacecraft, the Jupiter orbiter that captured images of Europa in the late 1990s.
2. Infrared light reflected from Europa will be analyzed to determine the moon’s surface composition.
Europa Clipper will also determine the moon’s surface composition. The mission’s imaging spectrometer will analyze infrared light reflected from Europa to look for organics, such as sulfates and carbonates, and other compounds. The instrument will measure the presence, absence, and strength of various wavelengths of light that help scientists infer composition. The imaging spectrometer will map Europa’s surface composition in detail, helping scientists understand Europa’s geologic history and the moon’s suspected ocean.
3. An ice-penetrating radar will search for subsurface lakes similar to those beneath Antarctica's ice sheet, and produce 3D images of Europa’s ice shell.
One of Europa Clipper’s instruments will use radar to penetrate the moon’s icy shell, searching for the suspected ocean beneath and studying the ice’s structure and thickness. The ice-penetrating radar will transmit radio waves that bounce off features within the subsurface ice.
This same technology has been used on Earth for decades to study the thickness and substructure of the ice sheets of Antarctica and Greenland. Europa Clipper’s radar will use two different frequencies of radio waves to penetrate Europa’s ice as much as 18 miles (30 kilometers) deep. Some radio waves will return to the spacecraft, but at a fraction of their original energy. By measuring the time difference between transmission and return, and knowing how fast radio waves travel through various materials, the radar instrument will tell us how far detected features are from the spacecraft. This will allow scientists to understand differences in material properties and produce detailed 3D images of the ice shell, including pockets of water within the ice shell that could serve as passageways for chemicals to move between the moon’s surface and the ocean below.
4. A magnetometer will measure the strength and direction of Europa’s magnetic field…
The mission will also carry a magnetometer to measure the strength and direction of the moon's magnetic field. Europa doesn’t independently generate its own magnetic field. But time-variations of Jupiter’s magnetic field induce a magnetic field within Europa, presumably via electric currents flowing in a salty ocean beneath Europa’s ice. On a boom 25 feet (8.5 meters) in length when fully deployed, Europa Clipper’s magnetometer instrument will measure the strength and orientation of both Europa and Jupiter’s magnetic fields during dozens of Europa flybys. The instrument will allow scientists to measure the depth and salinity of Europa’s suspected ocean as well as the ice shell’s thickness.
5. …and a plasma instrument will study the flow of plasma near Europa, helping to calibrate data from the magnetometer.
Jupiter’s magnetic field also carries charged particles in an ionized gas called plasma from the volcanic moon Io, Jupiter’s ionosphere, and Europa itself. This plasma distorts Europa’s induced magnetic field. The mission’s plasma instrument will study the density, temperature, and flow of plasma near Europa. The plasma instrument has four sensors called Faraday cups, which are metal cups designed to catch charged particles in space. Plasma creates an electrical current when it strikes a detector plate located within a Faraday cup, revealing the plasma’s speed and density. While interesting on its own, understanding the density, temperature, and flow of plasma will help calibrate data from the spacecraft’s magnetometer. The powerful combination of these two instruments is key to precisely determining Europa's ice shell thickness, and the depth and conductivity of its ocean.
6. Gravity experiments will also help determine the thickness of Europa’s ice shell.
Finding out the thickness of Europa’s ice shell is important for understanding whether places exist below the moon’s surface that could support life today. Thinner ice or water passing through the ice would help essential chemical building blocks on Europa’s surface reach the ocean, improving the odds that the moon could sustain life. While the spacecraft’s ice-penetrating radar and magnetometer will provide complementary means of measuring the ice shell’s thickness, gravity experiments will also allow scientists to get detailed measurements of the varying shape of Europa’s surface as it orbits Jupiter as well as detailed information about Europa’s subsurface.
Europa Clipper will pass through Europa’s gravity field nearly 50 times while the moon is at various distances from Jupiter. Europa’s gravity field is in part a result of the shape of the moon itself. By studying how Europa’s gravity field changes shape, scientists are measuring how the moon itself responds to tidal forces by Jupiter, as a result of its interior structure. In gravity experiments, radio antennas from NASA’s Deep Space Network will send radio signals to Europa Clipper. The spacecraft then retransmits radio waves to Earth at a different frequency, coherent to what it received. The gravity science team can then precisely analyze the Doppler shift and other aspects of the radio signal received on Earth. These gravity measurements, combined with the lines of evidence from the spacecraft’s ice-penetrating radar and magnetometer, will help constrain the possible thicknesses of Europa’s ice and ocean layers.
7. A thermal instrument will survey Europa's frozen surface in search of recent eruptions of warmer water at or near the surface.
Europa Clipper will carry a thermal emission imaging system that will analyze infrared light from Europa to map the temperatures across the moon’s surface. It will seek clues about activity, such as cryovolcanoes and regions where the moon’s suspected ocean may be near the surface. When part of Europa rotates out of sunlight, granular material cools faster than large blocks of material. The thermal imaging system will record surface cooling rates to learn about the texture of Europa’s surface. Mapping surface temperature and water near the surface will help to understand Europa’s small-scale properties.
8. An ultraviolet spectrograph will search for potential plumes of water vapor, and provide data on the moon’s surface and thin atmosphere.
By collecting ultraviolet light with a telescope and creating images, Europa Clipper’s ultraviolet spectrograph will search for potential plumes of water vapor that might erupt from Europa’s surface, in addition to providing data about the composition and dynamics of the moon’s thin atmosphere, and data about the composition of the moon’s surface. The instrument collects ultraviolet light and separates its wavelengths with an optical grating. The ultraviolet spectrograph will primarily identify relatively simple molecules, such as hydrogen, oxygen, hydroxide, and carbon dioxide.
9. A mass spectrometer will collect and reveal the molecular identities of gases in Europa’s faint atmosphere and from possible plumes.
In addition, the mission’s mass spectrometer will identify and analyze gases in Europa’s faint atmosphere and from possible plumes. The mass spectrometer will collect gases, convert them into charged particles called ions, and bounce the ions back and forth within the instrument. By timing their transit through the instrument, the mass spectrometer determines the ions' masses, thus revealing their molecular identities. It will study the chemistry of the moon’s suspected subsurface ocean, if and how the ocean and surface exchange material, and how radiation alters compounds on the moon’s surface
10. A dust analyzer will scoop up larger particles and identify their chemistry.
Tiny meteorites eject bits of Europa’s surface into space and a subsurface ocean or in-ice water reservoirs might vent material into space as plumes. To study this, Europa Clipper’s dust analyzer will scoop up larger particles from these plumes and identify their chemistry, revealing Europa’s surface composition including potential organic molecules. The dust analyzer can detect salts in the dust and ice grains, providing additional information about a subsurface ocean. If a subsurface ocean or reservoir is venting material into space as plumes, the dust analyzer will help us to determine if Europa’s water is suitable for some form of life.
Explore the Spacecraft
NASA's Europa Clipper spacecraft will conduct a detailed survey of Jupiter's moon Europa to determine whether the icy moon could harbor conditions suitable for life. Europa Clipper will carry an advanced suite of science instruments to discover whether Europa hosts environments suitable for life.