A recent study from NASA’s Juno mission unveils fascinating details about Europa, one of Jupiter’s moons. Using a tool called the Microwave Radiometer (MWR), scientists measured the ice shell surrounding its ocean. They found it to be about 18 miles (29 kilometers) thick, marking the first clear distinction between various models of shell thickness.
Europa is slightly smaller than Earth’s moon and is a key target in our search for life beyond Earth. Beneath its icy surface likely lies a salty ocean, which may contain essential ingredients for life. Understanding the thickness of this ice shell is crucial as it helps us piece together how the moon’s internal structure works and its potential for supporting life.
This new thickness measurement was published in Nature Astronomy in December 2022. Interestingly, the MWR was originally designed to study Jupiter’s atmosphere. However, it has also provided valuable insights into its moons, particularly Europa.
During its flyby on September 29, 2022, Juno approached within about 220 miles (360 kilometers) of Europa’s surface. The MWR collected data, analyzing almost half of the moon’s surface. This included measuring temperatures at various depths beneath the ice.
Steve Levin, the Juno project scientist from NASA’s Jet Propulsion Laboratory, mentioned, “The 18-mile estimate relates to the cold, rigid outer layer of a pure water ice shell.” He further explained that if there’s a warmer layer underneath, the total thickness could be even greater. If the ice contains some salt, our estimate might drop by around 3 miles.
The thicker ice shell suggests that oxygen and nutrients would have a longer path to travel from the surface to the ocean below, a critical factor in studying Europa’s habitability.
The MWR also uncovered interesting details about the ice just beneath the surface. It found “scatterers”—tiny features like cracks and voids that impact how microwaves reflect off the ice. These scatterers are quite small, around a few inches in diameter, and extend several hundred feet deep. Their size likely means they won’t significantly affect the transport of nutrients and oxygen from the surface to the ocean.
Scott Bolton, Juno’s principal investigator from the Southwest Research Institute in San Antonio, emphasized, “The size and existence of these features are key to understanding Europa’s potential for life.” This knowledge will also inform future missions like NASA’s Europa Clipper, slated to arrive in 2030, and the European Space Agency’s JUICE, arriving in 2031.
These missions are exciting because they aim to explore not just Europa but other icy moons of Jupiter. By studying these celestial bodies, scientists hope to uncover the mysteries of life beyond Earth.
For more in-depth information on Juno, visit NASA’s [Juno mission page](https://science.nasa.gov/mission/juno).
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Europa, Jet Propulsion Laboratory, Juno
