Europa

Galileo Images of Europa

Image Credit:

NASA/JPL/DLR

 

Europa is the fourth largest satellite of Jupiter, the smallest of the fours Galilean moons, and the second closest to Jupiter of the Galilean moons. It orbits 671,100 km from Jupiter and takes only 3.55 Earth days to go around Jupiter (twice that of Io). It has a density of 3.013 g/cm³, making it about 3 times that of water. It does have a lower density than Io, which will be explained in the next paragraph. It's radius is about 1561 km, making it smaller than the Moon, which is about 1738 km in radius.

Europa has a surface covered with ice and is believed to have subsurface liquid water under the ice. The water is kept liquid by two processes, the insulation from the ice and from tidal forces heating the interior, much like tidal forces keep the interior of Io molten. If life exists anywhere else in our Solar System, this may be the most likely place to look for life. However, any mission we send to Europa to find life would have to be very careful to be sterilized as any microbes hitching a ride from Earth would contaminate any detection techniques used on Europa to search for life.

Just recently, Europa was found possibly to experience plate tectonics, much like Earth. Slabs of ice may slide under each other, creating "Europa-quakes", much like earthquakes experienced on Earth as continental plate slide under and above each other. More information about plate tectonics can be found on space.com's article about Europan plate tectonics.

Artist's Concept of Plate Tectonics on Europa

Credit: Noah Kroese, I.NK

Close-up view of possible plate spreading on the surface of Europa

Credit: NASA/JPL