Animation depicts upward movement of water from Europa’s subsurface ocean
Scientists at NASA’s Jet Propulsion Laboratory (JPL) have created an animation simulating the possible upward movement of water from Europa’s subsurface ocean to its surface, by applying a numerical model used to study movement in Earth’s crust.
The animation was produced in a study that examined how geological activity on Europa, specifically deformation of the moon’s icy surface, could move its underground ocean water upward via linear tectonic bands and lanes that run through the moon’s icy outer shell.
Several hundred miles long and tens of miles wide, these structures result from brittle surface ice sitting on top of a convecting ice layer.
The two-dimensional animation shows a possible cross-section of one of these bands as it moves through the moon’s icy shell. Europa’s ocean is located at the bottom of the image while its surface ice is seen as a thick white line at the top. Between these two is the icy shell’s midsection, with hard, rigid ice shown in red, orange, and yellow.
Depth in kilometers is depicted via the vertical line on the graph’s left side while distance from the center of the surface band is shown in the horizontal line at the bottom. Passage of time, from 6,000 to 965,000 years, can be seen at the top of the image.
As time passes, viewers can see deformation of the outer ice shell, which occurs as a result of gravitational interaction with Jupiter. Brittle, cold ice at the top is pulled apart, causing the formation of faults, which are shown as diagonal yellow, green, and blue lines in the upper middle of the image. Eventually these faults heal, then reform in a cyclic process.
Where the liquid ocean makes contact with the frozen ice shell, material starts to churn. Viewers can see the churning material in the form of tiny white dots that constitute bits of the ocean frozen into the ice shell at the point of contact.
Because it takes between several hundred thousand and one million years for these bits of ocean to be transported to Europa’s surface, scientists consider these bits as samples of the ocean’s past rather than of its present. A spacecraft that studies them would reveal ocean conditions as they were long ago, which is why scientists refer to these bits as “fossil ocean material.”
Scheduled for launch during the early 2020s, NASA’s Europa Clipper will study the composition of Europa’s surface material and test this theory using ice-penetrating radar to observe the moon’s bands and lanes. The Clipper‘s infrared and ultraviolet instruments will then analyze ocean material conveyed to the surface to determine whether the ocean is habitable for microbial life.
Understanding the interaction and exchange of materials between ocean water and surface ice will enable scientists to better determine Europa’s habitability. Furthermore, Jupiter’s largest moon, Ganymede, also displays these bands and lanes and likely has a subsurface ocean of its own, meaning it could be experiencing the same processes and have the same potential habitability as Europa.
Image courtesy of NASA JPL
Laurel Kornfeld is an amateur astronomer and freelance writer from Highland Park, NJ, who enjoys writing about astronomy and planetary science. She studied journalism at Douglass College, Rutgers University, and earned a Graduate Certificate of Science from Swinburne University’s Astronomy Online program. Her writings have been published online in The Atlantic, Astronomy magazine’s guest blog section, the UK Space Conference, the 2009 IAU General Assembly newspaper, The Space Reporter, and newsletters of various astronomy clubs. She is a member of the Cranford, NJ-based Amateur Astronomers, Inc. Especially interested in the outer solar system, Laurel gave a brief presentation at the 2008 Great Planet Debate held at the Johns Hopkins University Applied Physics Lab in Laurel, MD.