The search for life beyond Earth has always been one of the most driving forces for interplanetary missions. And one of the most intriguing investigations concerns Jupiter and its moons. Among the 53 moons that orbit Jupiter, one of them, Europa, is filled with data suggesting the presence of water oceans beneath its surface, indicating that it may be habitable.
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As NASA prepares to launch its ambitious Europa Clipper mission to Jupiter's namesake moon, it wants to delve deeper into the mystery of water plumes spewing from the surface of the ice-covered ocean world. The spacecraft will study the moon from its deep interior to its surface to determine whether it has the ingredients that make it habitable.
Scientists said Europa is geologically dynamic and generates heat internally as its solid layers stretch and bend from the “gravitational tug” with its host planet and neighboring moons. It is not the Sun’s heat that prevents underground water from freezing on these ice-covered moons; instead, it is this heat generated from the interior that could stop freezing below the surface.
Scientists using the Galileo spacecraft, the Hubble and large Earth-based telescopes have reported detections of faint clouds of water or its chemical components on Europa. But no one is sure.
"We're still in the realm of where there's really interesting evidence, but none of it is certain," said Matthew McKay Hedman, a member of the Europa Clipper's Mapping Imaging Spectrometer for Europa (MISE) science team. These plumes, when studied by the Europa Clipper spacecraft, could offer insights into the moon's inner layers.
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Scientists first observed these mysterious plumes erupting from the surface of Saturn's moon Enceladus in 2005. The giant column of vapor, ice particles, and organic molecules spewing from the moon's south polar region suggests that there is an ocean of liquid water beneath Enceladus' icy shell and confirmed that the moon is geologically active.
These jets have propelled Enceladus and other worlds in the outer solar system, devoid of atmospheres and far from the Sun's heat, to the top of NASA's list of places to look for signs of life. "A lot of people think Europa is going to be Enceladus 2.0, with jets constantly shooting from the surface. But we can't see it that way. Europa is a completely different beast," said Lynnae Quick, a member of the science team behind Clipper's Europa Imaging System (EIS) cameras.
Europa is different from Enceladus, as it is much closer to Jupiter than Enceladus is to Saturn. More heat is generated on the moon from the friction generated as it orbits its host planet. "Since internal heat stimulates geological activity on rocky worlds, Europa is expected to have a more extensive geology than Enceladus," NASA said.
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The Europa Clipper mission is preparing to conduct the first dedicated and detailed study of an ocean world beyond Earth. The probe will determine whether this distant moon has conditions favorable for life. The mission's goal is to explore Europa to investigate its habitability.
The spacecraft is not being sent to find life, but will try to answer specific questions about Europa's ocean, ice shell, composition and geology. Europa was first discovered by Galileo in 1610, who also found three other moons, Ganymede, Callisto and Io, around Jupiter.
