Beneath Europa’s thick icy crust lies a vast, global ocean where snow floats upward on upturned ice peaks and sunken ravines. Strange underwater snow is known to occur beneath ice shelves on Earth, but a new study suggests the same is likely true on Jupiter’s moon, where it may play a role in building its ice shell.
Underwater snow is much cleaner than other types of ice, meaning Europa’s ice shell could be much less salty than previously thought. That’s important to mission scientists preparing NASA’s Europa Clipper spacecraft, which will use radar to peer beneath the ice shell to see if Europa’s ocean could be hospitable to life. The new information will be critical because salt trapped in the ice can affect what and how deep the radar will see in the ice shell, so being able to predict what the ice is made of will help scientists make sense of the data.
The study, published in the August edition of the journal Astrobiology, led by the University of Texas at Austin, which is also leading the development of Europa Clipper’s ice-penetrating radar instrument. Knowing what kind of ice Europa’s shell is made of will also help decipher the salinity and habitability of its ocean.
“When we explore Europa, we’re interested in the salinity and composition of the ocean, because that’s one of the things that will govern the potential habitability or even the type of life that might live there,” said the study’s lead author. Natalie Wolfenbarger, graduate student researcher at the University of Texas Institute for Geophysics (UTIG) at the UT Jackson School of Geosciences.
Europa is a rocky world the size of Earth’s moon surrounded by a global ocean and a mile-thick ice shell. Previous studies suggest that the temperature, pressure and salinity of Europa’s ocean closest to the ice is similar to what you’d find under an Antarctic ice shelf.
An illustration of NASA’s Europa Clipper spacecraft flying past Jupiter’s moon Europa. The spacecraft, which is scheduled to launch in 2024, will carry an ice-penetrating radar instrument developed by scientists at the University of Texas Geophysics Institute. Credit: NASA/JPL-Caltech.
Armed with this knowledge, the new study looked at the two different ways water freezes under ice shelves, condensed ice and brittle ice. Permafrost grows directly below the ice shelf. Frazil ice forms as ice flakes in supercooled seawater that float upward through the water, settling to the bottom of the ice shelf.
Both ways produce ice less salty than seawater, which Wolfenbarger found would be even less salty when scaled to the size and age of Europa’s ice shell. In addition, according to her calculations, brittle ice – which retains only a small fraction of the salt in seawater – could be very common in Europa. This means its ice shell could be orders of magnitude cleaner than previous estimates. This affects everything from its strength, to how heat moves through it, and the forces that can drive a type of ice tectonics.
“This paper opens up a whole new set of possibilities for thinking about ocean worlds and how they work,” said Steve Vance, a researcher at NASA’s Jet Propulsion Laboratory (JPL) who was not involved in the study. “It sets the stage for how we might prepare for Europa Clipper’s analysis of the ice.”
According to co-author Donald Blankenship, a senior researcher at UTIG and principal investigator for the Europa Clipper ice-penetrating radar instrument, the research is validation for using Earth as a model for understanding Europa’s habitability.
“We can use Earth to assess Europa’s habitability, measure the exchange of impurities between the ice and the ocean, and figure out where the water is in the ice,” he said.
Water on Jupiter’s moon closer to surface than thought: study More information: Natalie S. Wolfenbarger et al, Ice Shell Structure and Composition of Ocean Worlds: Insights from Accreted Ice on Earth, Astrobiology (2022). DOI: 10.1089/ast.2021.0044 Provided by The University of Texas at Austin
Reference: Underwater snow gives clues to Europa’s icy shell (2022, August 15) Retrieved August 15, 2022 by
This document is subject to copyright. Except for any fair dealing for purposes of private study or research, no part may be reproduced without written permission. The content is provided for informational purposes only.
