While NASA Popular Space Launch System stands ready for its maiden flight later this month with the aim of returning astronauts to the Moon within the next few years, our eyes are once again on the stars as we continue to ask the question that has plagued humanity for ages immemorial: Are we alone?
Although there are several places in the solar system from which we can choose to conduct our search for life beyond Earth, including the moons of Mars and Saturn, Titan and Enceladus, a planetary body orbiting the largest planet in the solar system has aroused the interest of scientists. since the 1970s.
Jupiter’s second Galilean moon Europa, with its inner ocean, mostly crater-free surface, and criss-crossing fissures and ridges spanning entire hemispheres, makes it one of the most fascinating planetary bodies ever observed. These unique geological features may indicate that liquid water is rising to the surface from its deep ocean, making Europa a hotspot for exploration and the study of life beyond Earth, also known as the name of astrobiology.
“Europe may be one of the few accessible places where life could arise and persist,” says Michael Manga, geophysicist and professor in the Department of Earth and Planetary Sciences at UC Berkeley. “Its evolution and dynamics are fascinating, some similarities but also fundamental differences with Earth.”
Scientists hypothesize that Europa’s icy outer shell is 15 to 25 kilometers (10 to 15 miles) thick and floats on an ocean 60 to 150 kilometers (40 to 100 miles) deep. While there is strong evidence that Saturn’s moon Enceladus also has an inner ocean, Europa’s ocean is thought to potentially hold twice the amount of water of all of Earth’s oceans combined, although Europa only accounts for a quarter of the diameter of the Earth.
“The composition of Europa’s surface and some of its geological features suggest that water from the ocean is somehow moving through the shell and reaching the surface,” explains Alyssa Rodensenior scientist in the Planetary Science Branch of the Southwest Research Institute in Boulder, Colorado.
“If this is true, it means that nutrients and energy can flow between the ocean, the ice shell and the surface, and this can benefit life.”
There is already evidence that this liquid water rose to the surface in the form of what is called “Chaotic Terrain” which is a highly disturbed topography where blocks of ice have broken off, moved, and then re-frozen to the surface due to lack of atmosphere and being exposed directly to the vacuum of space.
An example of chaotic terrain on Europa is Conamara Chaos, which was imaged by NASA’s Galileo spacecraft and later rebuilt to show what it looked like before the surface disturbance happened.
Europa’s vast ocean swirls beneath its icy crust despite the Moon’s incredible distance from the Sun, placing it far beyond our star’s habitable zone, which is the sweet spot where liquid water can exist at the surface of a planet. Instead, this ocean exists from what is called tidal heating, or the small moon’s constant stretching and squeezing endures as it orbits the much more massive Jupiter throughout its elliptical orbit. Along with Jupiter, Europa is also constantly pulled by Jupiter’s moons Io and Ganymede, the first and third Galilean satellites, respectively. This tidal warming leads to friction within Europa’s core, corresponding to the heating and eventually melting of the interior ice in what is now the massive ocean of Europa.
“I find Europa captivating because its geology, interior and orbit are all linked by the process of the tides,” says Rhoden. “Europa’s gravitational relationship with Jupiter and its neighboring moons is responsible for creating this complex and active world. Each aspect you study is related to the others, so there are many ways to investigate the processes at work and many sources of curiosity.
While Europa has been studied extensively with past space missions including NASA’s Galileo mission 1990s and early 2000s, NASA’s next project European Clipper The mission proves to be a game-changer in terms of our understanding of this fantastic icy moon, scheduled for launch in late 2024 with orbital insertion around Jupiter accomplished in early 2030. Clipper’s primary goal is to determine the habitability potential for locations below the ice surface while making nearly 50 extremely close flybys of the icy moon, some as low as 25 kilometers (16 miles).
“I started researching Europa 22 years ago, and I had the same images to work with all the time,” says Rhoden.
“So I would say I’m EXTREMELY excited for the new datasets that will be delivered by Clipper. As for habitability, there are probably many ways to inform habitability, but what interests me the most is the presence of liquid water in the ice shell.
Since water is the reason life thrives here on Earth, what kinds of life might we find crossing the inner ocean of Europa?
While Rhoden jokingly says, “Space whales, obviously”, Manga is less optimistic, saying a gut feeling tells him there is no life, but concludes by saying he will take samples from a lander to be sure.
Will Europe and its vast ocean finally answer the long-standing questions of whether we are alone in the universe? Only time will tell, and that’s why we do science!