Europa is one of many moons which orbit the planet Jupiter. For years now we have known that Europa most likely has an ocean of water lurking deep under the frozen icy surface. The surface of Europa is almost all water ice. It has cracks on the surface resembling many found here on Earth. How does it get warm enough for water to exist under the surface? Tidal forces from Jupiter and other moons are causing Europa to flex, generating interior warmth.
Europa has been a prime focus for life as well, since the 1980s. Arthur C. Clarke in "2010" used it. If water exists on Europa and it most likely does, this would also change our focus on where to look for life in the universe and how it may come to exist.
New data from the Galileo spacecraft have found blocks of ice on the surface that suggest an interaction between the icy surface and a sub-surface lake of water.
The Galileo spacecraft has been taking pictures of the surface of Europa. It uses a combination of optical and photoclinometry to do so (using pictures to measure the heights of surface features). In the terrain image below, purple and red are elevated terrain. The depression in the image is most likely something called "chaotic terrain". The smaller, unorganized regions are most likely from pockets of water that could be the size of the Great Lakes.
The artists view as below, shows how thick the ice is, but certain areas, just below the ice, have melted. The ice that is above the area is thinner, in the neighborhood of a few miles thick, which would explain the localized chaos seen by Galileo.
Life and water
This all pretty exciting because with the ability for light to penetrate into the water means biology could be at work in the water. Evidence suggests, based on Galileo's imagery, that the lake pictured above is still forming. None of this means life exists there, but the possibility is intriguing. This forces us to expand how we think of life in the universe, to other locations not thought possible before.
Unfortunately it may be some time before we get the chance to physically explore Europa. The proposed Europa Jupiter System Mission (EJSM), spacecrafts that would orbit Jupiter and Europa would cost $4.6 billion.
Source: DiscoverMagazine, NASA
Images: University of Texas at Austin/NASA
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