Written by Lola Gayle

NASA researchers reported on Tuesday that certain dark features on the surface of Jupiter’s moon Europa may actually be sea salt from a subsurface ocean which has become discolored due to radiation. This suggests the ocean could be interacting with rocky seafloor, “an important consideration in determining whether the icy moon could support life.”

Images of Europa’s geological features have fascinated scientists for years.

“We have many questions about Europa, the most important and most difficult to answer being is there life? Research like this is important because it focuses on questions we can definitively answer, like whether or not Europa is inhabitable,” said Curt Niebur, Outer Planets Program scientist at NASA Headquarters in Washington, in a recent statement.

“Once we have those answers, we can tackle the bigger question about life in the ocean beneath Europa’s ice shell.”

“If it’s just salt from the ocean below, that would be a simple and elegant solution for what the dark, mysterious material is,” added research lead Kevin Hand, a planetary scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California.

A close-up of salt grains discolored by radiation following exposure in a "Europa-in-a-can" test setup at JPL. Credit: NASA/JPL-Caltech
A close-up of salt grains discolored by radiation following exposure in a “Europa-in-a-can” test setup at JPL. Credit: NASA/JPL-Caltech

In order to root out the underlying mechanisms behind these features, the researchers created what they call ‘Europa in a can.” To do this they simulated Europa’s surface looking for possible candidate substances. They used common salt – sodium chloride – as well as mixtures of salt and water.

“The lab setup mimics conditions on Europa’s surface in terms of temperature, pressure and radiation exposure. The spectra of these materials can then be compared to those collected by spacecraft and telescopes,” Hand said.

After subjecting their salty samples at Europa’s chilly surface temperature of minus 280 degrees Fahrenheit (minus 173 Celsius) and bombarding them with an electron beam to simulate the moon’s intense radiation, the researchers found that they turned a yellowish-brown color. In other words, the resulting colors showed a strong resemblance to those within Europa’s fractures. In fact, the longer the samples were exposed to radiation, the darker the resulting color.

This research has been accepted for publication in the journal Geophysical Research Letters.

For more information about Europa, visit: http://europa.jpl.nasa.gov/

Top image courtesy NASA/JPL-Caltech/SETI Institute

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