Europa: Our best shot at finding alien life?
By Paul Rincon
Science editor, BBC News website, The Woodlands, Texas
9 hours ago
From the section Science & Environment
After two decades of development and "heartbreak", scientists are on the verge of sending missions to explore the ocean world of Europa. Could this be our best shot at finding life elsewhere in the Solar System?
Orbiting the giant planet Jupiter is an icy world, just a little smaller than Earth's moon. From a distance, Europa appears to be etched with a nexus of dark streaks, like the product of a toddler's chaotic scribbling. Close up, these are revealed to be long linear cracks in the ice, extending in some cases for thousands of kilometres. Many are filled with an unknown contaminant that scientists dub the "brown gunk". Elsewhere, the surface is tortured and irregular, as if massive slabs of ice have drifted, spun and flipped over in slush.
Jupiter's immense gravity helps generate tidal forces that repeatedly stretch and relax the moon. But the stresses that created Europa's smashed up terrain are best explained by the ice shell floating on an ocean of liquid water.
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Europa's briny deep might extend 80-170km into the moon's interior, meaning it could be holding twice as much liquid water as there is in all of Earth's oceans.
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Now, Nasa is priming two missions to explore this intriguing world. Both have been discussed here at the 48th Lunar and Planetary Science Conference (LPSC) in Houston. The first is a flyby mission called Europa Clipper that would likely launch in 2022. The second is a lander mission that would follow a few years later. Dr Robert Pappalardo, from Nasa's Jet Propulsion Laboratory, is Clipper's project scientist.
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