Europe could be one of the few accessible places where life could arise and survive.
As NASA ‘s much-hyped Space Launch System prepares for its maiden flight later this month, with the goal of sending astronauts to the moon in the coming years, our eyes turn back to the stars as we continue to ask ourselves the question that has plagued humanity since ancient times: Are we alone?
While there are several places in the solar system that are candidates for the search for life beyond Earth, including Mars and Saturn’s moons Titan and Enceladus, one planetary body orbiting the largest planet in the solar system has piqued the interest of scientists since the 1970s.
Jupiter’s moon Europa, with its inner ocean, mostly crater-free surface, and crisscrossing trenches and ridges covering entire hemispheres, is one of the most fascinating planetary bodies ever observed.
One of the few accessible places where life could exist
These unique geological features may indicate the presence of liquid water coming to the surface from its deep ocean, making Europa a hotspot for the study of life beyond Earth, also known as astrobiology.
“Europa could be one of the few accessible places where life could emerge and persist,” said Michael Manga, a geophysicist and professor in Berkeley College’s Department of Earth and Planetary Sciences.
“Its evolution and dynamics are fascinating; there are some similarities but also fundamental differences with Earth.”
Scientists suspect that Europa’s icy outer shell is 15 to 25 kilometers thick and floats on an ocean 60 to 150 kilometers deep. While there is strong evidence that Saturn’s moon Enceladus also has an inner ocean, it is thought that Europa’s ocean could contain twice as much water as all of Earth’s oceans combined, even though Europa is only one-quarter the diameter of Earth.
Why is Europa special?
“The composition of Europa’s surface and some of its geologic features suggest that the ocean’s water somehow moves through the crust and reaches the surface,” says Alyssa Rhoden, senior research scientist in the Planetary Sciences Directorate at Southwest Research Institute in Boulder, Colorado.
“If this is true, it means that nutrients and energy can flow between the ocean, the ice sheet and the surface, which can be beneficial for life.
There is already evidence that this liquid water has reached the surface in the form of what is known as “chaotic terrain,” a highly disturbed topography in which blocks of ice have broken off, moved, and then refrozen at the surface because there is no atmosphere and they are directly exposed to the vacuum of space.
Beneath Europa’s ice crust simmers a vast ocean, despite the moon’s incredible distance from the sun, which places it well outside our star’s habitable zone, the ideal point at which liquid water can exist on a planet’s surface. Instead, this ocean exists because of what is known as tidal heating, the constant stretching and compression that the tiny moon experiences as it orbits the much more massive Jupiter in its elliptical orbit.
Future missions to Jupiter’s moons
In addition to Jupiter, Europa is also constantly attracted to Jupiter’s moons Io and Ganymede. This tidal heating causes friction in Europa’s core, which heats up and eventually melts the ice inside to form what is now Europa’s great ocean.
The gravitational relationship between Europa and Jupiter and its neighboring moons is responsible for the formation of this complex and active world. Every aspect that is studied is connected to the others. So there are many ways to study the processes going on, and many curiosities,” Rhoden says, according to Inverse.
While Europa has been studied in depth by previous space missions, most notably NASA ‘s Galileo mission in the 1990s and early 2000s, NASA ‘s upcoming Europa Clipper mission could fundamentally change our understanding of this fantastic icy moon. Launch is scheduled for late 2024, with orbit around Jupiter expected in the early 2030s.
The main goal of the Clipper mission is to test the habitability of places beneath the icy surface, making nearly 50 extremely close flybys of the icy moon, some accurate to within 25 kilometers.