Europa Clipper

Europa Clipper, robotic, solar-powered orbiter launched to Jupiter’s moon Europa by the National Aeronautics and Space Administration (NASA) on October 14, 2024. The spacecraft—at the time of its launch the largest developed by NASA for a planetary mission—aims to understand the nature of the icy shell covering Europa’s surface, gain insights into the ocean that is thought to exist beneath this icy layer, and study the moon’s chemical composition and geology to discover signs of habitability.

Mission objectives, background, and method

Europa, one of the four large Galilean moons of the gas giant Jupiter, has a thick icy shell that may shelter a subsurface ocean—as strongly suggested by Galileo spacecraft data—with twice as much water as Earth. Scientists think that it could have the available energy and essential chemical elements to support life. NASA and the U.S. National Research Council have identified Europa as one of the most promising locations in the solar system to search for signs of life.

The Europa Clipper is designed to make 49 close flybys of the moon—some as close as 25 km (16 miles) above its surface—amid the high-radiation environment near Jupiter. Nine specialized instruments will gather visual as well as particle data from Europa’s environment.

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The Europa Clipper’s project scientist, Robert Pappalardo, has described the mission as “the first in-depth exploration of an ocean world.” One way the Europa Clipper will conduct this exploration is by checking the surface for plumes that may arise from the subsurface ocean. These plumes could show how subsurface minerals are dispersed on the surface. Moreover, they could point to the existence of subsurface hydrothermal vents, similar to those that support life on Earth far below the reach of the Sun’s rays.

Analysis of Europa’s geological activity could explain why Europa has a relatively smooth surface. Europa has very few impact craters from small bodies, indicating that any such craters were likely smoothed away by geological movements. Scientists have suggested that sufficient evidence of geological and plume activity in this mission could make future studies into Europa’s habitability more viable.

Energy and radiation

The Europa Clipper is NASA’s biggest planetary exploration spacecraft, at about 5 meters (16 feet) tall and more than 30 meters (100 feet) wide with all its solar arrays deployed. These solar panel arrays provide energy to the orbiter. They are so wide because the amount of solar energy in Jupiter’s orbit, so far from the Sun, is too weak for smaller arrays to supply sufficient energy to power the orbiter.

The Clipper needs to orbit Jupiter instead of Europa itself because of the high-radiation environment around the moon. On each flyby of Europa the spacecraft will be exposed to “the equivalent of a million chest X-rays” in radiation, according to NASA. The Europa Clipper will avoid long exposure to the high radiation around Europa by doing flybys of the moon before moving to safer, lower radiation zones far from Jupiter. The Clipper’s instruments are placed in a large electronics radiation protection vault with aluminum-zinc walls about 9 mm (0.4 inch) thick.

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Trajectory

The Europa Clipper was launched from Kennedy Space Center on a SpaceX Falcon Heavy rocket. Earth and Mars, as well as Ganymede and Callisto (moons of Jupiter), will provide gravity assists along the Clipper’s trajectory. The launch of the probe was timed for the orbiter to be able to pass through the gravitational fields of these bodies so that it is propelled, like a stone from a slingshot, toward Europa.

The orbiter will complete its 2.9 billion-km (1.8 billion-mile) course to Europa by April 2030. It will not return to Earth but will instead use its high-gain radar antenna to transmit accurate data back to Earth over a four-year period.