Image: Europa's surface, via NASA/Wikimedia Commons
There’s just something about Jupiter’s moon, Europa. It inspires movies, crowdsourced long-term plans to visit it, and was singled out by President Obama for $15 million of NASA’s shrinking budget, in order to look for signs of life on the icy moon. Only problem is that NASA estimated that sending a spaceship to Europa would cost between $2 billion and $4.7 billion. So if we can’t go to Jupiter’s moon, let’s just bring the moon here.
That’s basically what researchers at Centro de Astrobiología has done. The Spanish team simulated Europa-like conditions in a lab on outside of Madrid. They want to understand how Europa’s icy surface—one of the solar system’s smoothest objects—becomes crisscrossed with reddish fissures, and see if the features could emerge from the ocean that scientists speculate is below Europa’s surface, made from water, salts, and gases.
They reproduced the 300 bars of pressure and the low temperatures of around -4 degrees Celsius that characterize fluid reservoirs in Europa’s crust. If that seems fairly warm for something so far from the Sun (I think that’s the temperature it was this morning on Earth when I rode my bike to work), remember that tidal flexing warms Europa’s core, which may allow for a liquid ocean, even as the surface of Europa is on average some 170 degrees below zero.
The researchers then observed what happens to a solution of water, carbon dioxide, and magnesium sulfate—compounds detected on Europa’s surface detected with spectrometry—if it were emerging from the core of Europa and cooling as it headed to the surface.
"Just like Earth's magma emerges to the surface, a similar phenomenon could occur in Europa,” said says Victoria Muñoz Iglesias, one of the authors of the study, which was published in the journal Geochimica et Cosmochimica Acta. “Although, in this case it would be a watery cryomagma that would evolve and emerge outwards from the interior of the icy moon."
What resulted were processes similar to volcanism on Earth, but at temperatures below zero. Three types of minerals are formed depending of the fluid's evolution: ice, crystals trapping carbon dioxide, and very hydrated magnesium sulfates. As the different compounds cooled and crystallized, they revealed how Europa’s weird topography emerged—sometimes piling on the carbon dioxide crystals, sometimes the gas is released and piles collapse. Charged particles from Jupiter that bombard Europa’s surface are thought to produce the reddish, sulfurous compounds.
It’s more evidence supporting the hypothesis that under Europa’s still surface, there is water running. “Certain characteristics of Europa´s surface regarding its composition, morphology, and topography might be explained if a saline aqueous medium is involved, which has important consequences for living beings on Earth," said Muñoz-Iglesias.
Like maybe cash-strapped NASA should tap the National Oceanic and Atmospheric Administration to chip in to send a probe to Europa's salty subsurface seas.