NASA scientists have recently discovered the mysterious dark stripes on Europa’s surface are infect sea salt from a subsurface ocean, not sulfur. The material is discolored due to prolonged exposure to high levels of radiation, which cause it to turn black.
It seems like the more NASA explores other planets, the more likely it becomes that most of them once hosted life. Jupiter’s icy moon Europa is no exception and the question of whether or not it could host human life still remains.
The mere presence of sea salt on Europa’s surface suggests that the vast underground ocean is interacting with its rocky sea floor. It’s without uncertainty one of the main considerations in determining if it could indeed support life.
Curt Niebur, Outer Planets Programme scientist at NASA, empathized that this is the most important questions scientists have about the planet: “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”.
He went on to inform that once they have the answers to those basic questions, they will be able to tackle the bigger questions about life in the ocean beneath Europa’s ice-covered surface.
The new finding, published in the journal Geophysical Research Letters, comes after about a decade of scientists wondering about the nature of the dark material that coats long, linear fractures and other relatively young geological features on Europa.
Previous data from the Galileo spacecraft and various telescopes led researchers to believe that the material was a mix of sulfur and magnesium. Now, after noticing the material’s association with young terrains, they concluded that it has erupted from within Europa.
In order to test their theory, scientist created an environment that mimicked Europa’s temperature, pressure and radiation exposure. They then simply took various materials (different mixes of salt and water), put them in the environment for 30 hours (the equivalent of 100 years on Europa), and checked to see which of them most resembled what they had observed on Europa.
To do that, they had to collect the spectra (which they see as a kind of chemical fingerprints) encoded in the light reflected by the materials and compared them to those collected by spacecrafts and telescopes. They playfully called it “Europa in a can” and revealed that the longer the samples were exposed to the environment, the darker they got, which could help them pinpoint the exact age of some of Europa’s features based on their color.
Not all scientists are 100 percent comfortable claiming that the dark stripes are sea salt, as Kevin Hand, lead researcher and planetary scientist at NASA carefully worded his statement saying that if it is jus salt from the underground ocean, than that would be a very a simple and elegant explanation for what the dark material is.
They all agree however that, having no atmosphere of its own, the moon is constantly being bombed with high-levels of high-speed radiation from Jupiter’s magnetic field. This is something that they are certain has a part to play in creating the material.
More answers will likely be revealed somewhere in the early-to-mid 2020s, when NASA will be launching a mission to Europa. They intend to land on its surface and dig deep into its oceans in search of aquatic life forms.
Image Source: seasky.org