Exploring the Next Frontier in Our Search for Life With Europa Clipper

On Oct. 14, 2024, NASA's Europa Clipper launched on a journey to investigate one of the next frontiers in our search for life beyond Earth. Its destination: Jupiter's moon Europa. Beneath its icy crust, the small moon is thought to contain a saltwater ocean with more water than all of Earth’s oceans combined. By studying the moon up close with a suite of scientific instruments, Europa Clipper aims to improve our understanding of the conditions on Europa and explore whether the moon could be suitable for life.

Read on to learn why scientists are so interested in this tiny ocean world and get to know the science behind the Europa Clipper mission. Then, follow along with the mission in the classroom using STEM teaching and learning resources.

In recent years, scientists have discovered likely water worlds throughout our solar system that might harbor conditions suitable for life. But scientists are especially intrigued by Jupiter's moon Europa because it hosts several components that make it one of the most promising for harboring a habitable environment.

Slightly smaller in size than Earth's Moon, Europa is one of Jupiter’s 95 officially recognized moons. Europa was discovered along with Jupiter's three other largest moons more than 400 years ago by astronomer Galileo Galilei, and named by astronomer Simon Marius, who discovered Europa around the same time.

Scientific observations of Europa by previous spacecraft, including the Galileo mission to Jupiter, point to the existence of a subsurface salty ocean. These observations included spectroscopic measurements indicating the surface is mostly water ice; gravitational and moment-of-inertia measurements indicating a layered internal structure, including a water and ice layer near the surface that is 62 miles (100 kilometers) thick; and magnetic field measurements indicating a conductive layer near the surface. A salty ocean would explain these observations.

Though Europa has been studied by the Galileo spacecraft and the more recent Juno spacecraft with a few up-close flybys, Europa Clipper will allow us to build on previous findings to gain new perspectives on the moon with a Europa-dedicated mission.

Europa’s surface is crisscrossed by long, linear fractures, cracks, ridges, and bands. This ice shell is probably 10 to 15 miles (15 to 25 kilometers) thick. Evidence suggests that below Europa’s icy surface there is a saltwater ocean that is about 25 times deeper than Earth's oceans and contains about twice as much water. Scientists are hopeful that the Europa Clipper mission will refine these estimates.

In addition to water, Europa could have other conditions needed for life as we know it, including chemistry, energy, and stability. NASA scientists believe that six essential chemical building blocks for life exist on Europa and have likely existed there since Europa formed. These common elements are carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur.

Chemical energy, similar to that produced by hydrothermal vents found on Earth’s ocean floor, may also exist on Europa’s sea floor. As Europa orbits Jupiter, it gets stretched and released by the tug of gravity from the giant planet. This process, called tidal flexing, creates heat, much in the same way a paperclip that is repeatedly bent back and forth can get hot to the touch. This tidal flexing process could keep the ocean liquid and may also be creating heat that could be released through hydrothermal vents on the ocean floor. On Earth, hydrothermal vents spew forth heated water, minerals, and various chemicals that react with the salty ocean, releasing stored chemical energy.

Radiation surrounding Jupiter is another possible source of fuel for life in an ocean below Europa's surface. Jupiter’s strong radiation bombards Europa, which is bad news for anything attempting to live on the surface. But the radiation splits apart water molecules at the surface. Once the water molecules are split, the hydrogen floats away into space and the oxygen stays behind, making it available to bind to other elements. If the oxygen makes its way to the ocean through cracks or openings, it could react with other chemicals to provide chemical energy for microbial life.

In addition to these potentially life-supporting conditions, observations indicate that the environment on Europa has likely remained constant for four billion years. Environmental stability is important to allow time for life to form and evolve. Such a promising stable environment is ripe for further exploration.

The Europa Clipper spacecraft will be the largest in NASA’s planetary mission history, measuring 16 feet (five meters) in height. Its giant solar arrays, the largest space-faring solar arrays to date, unfold in space to span the length of a basketball court, more than 100 feet (30.5 meters), and cover 950 square feet (90 square meters). Such an enormous light-collecting area is required because the intensity of the Sun near Jupiter is only 3% of what it is on Earth, and the massive arrays need to capture enough sunlight to power Clipper’s science instruments.

Europa Clipper has a powerful suite of nine science instruments designed to work together to study Europa’s surface features, improve our understanding of the moon’s icy shell, examine the interaction between the ocean and the icy shell, and investigate the ocean’s composition to determine if it has the ingredients to sustain life.

The spacecraft will collect images and generate surface maps using its onboard cameras and spectrometers which can identify chemical signatures from reflected light. The Europa Imaging System contains wide-angle and narrow-angle cameras, which will produce high-resolution color and stereoscopic images of Europa. These cameras will study Europa's geologic activity and measure surface elevations. The Europa Thermal Emission Imaging System will use infrared light to measure surface texture and characterize warmer regions where the liquid ocean may be closer to the surface. It will also show any visible evidence of water eruptions. The Europa Ultraviolet Spectrograph will use a telescope to collect ultraviolet light to help determine the makeup of Europa's sparse atmospheric gases and surface materials. It will also search for signs of plumes erupting from the surface.

A mass spectrometer and dust analyzer will measure the composition of tiny particles in Europa’s extremely thin atmosphere and surrounding environment. The mass spectrometer, or MASPEX, will analyze gases in Europa’s sparse atmosphere and in any plumes, as well as the chemical makeup of the ocean. The Surface Dust Analyzer will identify the chemistry of solid material ejected from Europa to offer clues about the surface composition and ocean salinity.

The spacecraft will search for water under Europa’s surface using radar and will gather magnetic field measurements with a magnetometer. An ice-penetrating radar instrument called REASON will examine the ice structure and thickness. It works by transmitting radio waves that bounce off of features within the ice, like cracks or pockets of water. By measuring the time difference between transmission and return, REASON will learn how far the features are from the spacecraft, and therefore, how deep they are in the ice. This highly specialized and advanced radar can also measure differences in the composition of materials on Europa. It does this by measuring the energy difference between transmitted and returning signals and combining them with distance measurements.

The Europa Clipper Magnetometer works by measuring small changes in Europa’s magnetic signal and how they vary with time and location. Measuring Europa’s magnetic signal could confirm the existence of an ocean and will help determine the ocean’s depth and salinity as well as the thickness of the moon's icy shell.

These instruments work in conjunction with several other instruments to closely study Europa during the flybys and return data for scientists to analyze for years to come. Explore a full list of instruments and learn how they work on the Europa Clipper mission website.

To save fuel for its journey to Europa, the spacecraft will follow what’s known as a Mars-Earth Gravity Assist trajectory for its 5.5-year journey. This path will first take the spacecraft near Mars to get a gravity assist – a boost in momentum obtained by tugging on Mars, thereby slightly decreasing Mars’ orbital momentum while transferring that momentum to the spacecraft. Next, Europa Clipper will swing back by Earth for another gravity assist before continuing on to Jupiter for its scheduled arrival in April 2030.

Once it arrives, Europa Clipper will orbit Jupiter in an elongated ellipse that will bring the spacecraft close to Europa about 50 times. The orbit was designed in this way to decrease the impact of Jupiter’s radiation on the spacecraft, which can damage its electronics. Studies show that a spacecraft orbiting Europa may survive for a few months, while one orbiting Jupiter would last for many years. After each close flyby of Europa, the spacecraft will travel outside Jupiter’s radiation belts to downlink data to Earth, uplink new commands, and prepare for the next flyby.

The Europa Clipper mission launched from NASA's Kennedy Space Center in Florida on Oct. 14, 2024. Watch highlights from the launch in the video below.

To follow along with the mission as it makes its journey to Jupiter, visit the Europa Clipper mission website for all the latest mission updates, images, and science.

The Europa Clipper mission is a great opportunity to engage students with hands-on learning opportunities that range from imagining alien life forms to finding Jupiter in the night sky to engaging in the same science that led scientists to suspect the existence of Europa’s salty ocean. Explore these lessons and resources to get students excited about the STEM involved in this mission to determine if life-supporting conditions exist on Europa.

• Build Your Own Spacecraft Paper Model
• Build Your Own Spacecraft Toy Bricks Model
• Print a 3D Model of Europa Clipper
• Downloadable Europa Clipper
• Europa Clipper Mission Posters, Stickers, and More

• Europa Clipper Website
• Astrobiology @ NASA

• Europa Clipper Mission Videos

• Europa Clipper Mission Images

• Latest Europa Clipper News
• Mission Updates