An investigation into the material, which lines long cracks in the surface of the moon, has revealed that it may be sea salt which originates from an ocean hidden below the surface. Scientists believe that an ocean of liquid water lies beneath the layer of ice which coats Europa.
Strong evidence that salt exists on the surface of Europa
It is thought that the ocean does not freeze due to powerful tidal forces exerted on the moon by Jupiter’s gravitational field. Scientists believe that it could contain more water than all of Earth’s oceans together, and conditions may make it able to support life.
Scientists first noticed the dark material over ten years ago, and now a laboratory experiment carried out by NASA suggests that it is ordinary salt. Researchers simulated conditions on Europa by chilling samples of common salt and bombarding them with electrons, and found that the salt turned a similar color to those of the stripes found on the moon’s surface.
The salt turned darker the longer it was exposed to the electrons, and Dr. Kevin Hand of Nasa’s Jet Propulsion Laboratory said: “This work tells us the chemical signature of radiation-baked sodium chloride is a compelling match to spacecraft data for Europa’s mystery material.”
Could Europa host some form of life?
Scientists are excited by the possibility of finding some form of marine life on Europa, thanks to the combination of salty water and the relative warmth below the moon’s icy surface.
Dr Curt Neibur, Outer Planets Program scientists at Nasa, pointed out that of the many questions that scientists have about Europa, the most important concerns the existence of life on the moon. “Research like this is important because it focuses on questions we can definitively answer, like whether or not Europa is inhabitable. Once we have those answers, we can tackle the bigger question about life in the ocean beneath Europa’s ice shell,” he said.
A new mission to Europa is planned for 2025, which NASA will use to map the surface of the moon in greater detail than before. There are also tentative plans for an ambitious mission which would involve landing on the moon’s surface and drilling down through the ice, potentially sending a small submarine into the ocean below.