Scientists at NASA have found evidence using laboratory experiments that the dark material that dusts the surface of Europa, Jupiter's ice covered moon, may actually be sea salt from a subsurface ocean.
Sea salt on the surface of the moon suggests that the ocean is actually interacting with its sea floor. According to NASA, this is a positive indication towards discovering if the icy moon could support life.
"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. "Once we have those answers, we can tackle the bigger question about life in the ocean beneath Europa's ice shell."
According to scientists, the surface of Europa is constantly bombarded by radiation caused by Jupiter's magnetic field and the new study proposes that the mysterious dark matter is actually salt that has been irradiated. This dark material covers far-reaching linear fractures and other young geological features on the moon, suggesting that it erupts from within the moon's body and then over time becomes discolored.
"If it's just salt from the ocean below, that would be a simple and elegant solution for what the dark, mysterious material is," said research lead Kevin Hand, planetary scientist at NASA JPL.
Hand and researchers simulated a patch of the surface of Europa in a vacuum chamber set to Europa's surface temperature of 280 degrees Fahrenheit and then tested mixtures of sodium chloride. The samples were then blasted with an electron beam designed to simulation the radiation from Jupiter for tens of hours. After the exposure, the samples turned from white to yellowish-brown and the longer they were exposed, the darker they became.
"We call it our 'Europa in a can,'" Hand said. "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."
"This work tells us the chemical signature of radiation-baked sodium chloride is a compelling match to spacecraft data for Europa's mystery material," Hand said.
Currently, NASA is planning a $2.1 billion mission to Europa in 2022 designed to study its habitability and the plumes of water vapor. NASA recently awarded funding to develop an eel-like robot that may one day allow us to explore Europa and other moons around Jupiter.
