The lines on the surface are cracks in the ice some of which are 3,000 kilometers long
Europa is the sixth moon in distance from the planet Jupiter and the fourth largest.
Europa's diameter is 1,940 miles (3,122 kilometers), slightly smaller than Earth's moon.
Europa takes three and a half days to orbit Jupiter at an average distance of 416,900 miles (670,900 kilometers).
The same tidal forces found on Io also apply to Europa.
Jupiter's huge gravitational force heats up Europa's interior, melting the ice underneath its surface producing a salty ocean which could be as much as 62 miles (100 km) deep.
There is possibly twice as much liquid water on Europa as there is on Earth.
The darker areas on Europa's surface are suggestive of microbial life.
Europa is thought to have an iron core just like Earth.
The moon was discovered in January 1610 by the Italian astronomer Galileo Galilei.
Europa is sometimes referred to as Jupiter II (Jupiter 2).
The spots seen here are 10 km across, suggesting warmer ice rising from below
The surface of Europa is covered with a thick layer of ice. It is incredibly smooth with very little change in altitude,
there are also very few notable craters due to the splitting and shifting of the surface
removing any impacts.
Europa has an extremely tenuous atmosphere comprising of oxygen.
Europa's surface temperatures range from -160C to -220C (-260F to -370F). Scientists can only speculate on the temperature of the ocean which lies beneath
its surface but it is obviously warm enough for liquid water to exist.
Future space probe in Europa's ocean
Life on Europa
Apart from Earth, Europa holds the most intriguing prospects for life in the entire Solar System. Some scientists speculate that Europa's ocean could be teeming with life
although most think that life would take the form of micro-organisms living near hot vents on the ocean floor.
Origin of Name
Originally Galileo named the moons with roman numerals, Jupiter I, II, III and IV which persisted until the mid 20th century.
The naming of the moons after the lovers of Zeus from Greek mythology was suggested by the German astronomer Simon Marius who claimed he discovered the moons before Galileo but this has never been proven. Europa is named after the daughter of the king of Tyre.
Missions to Europa
JUICE (JUpiter ICy moon Explorer)
Launch: 2022 Arrival: 2030 Agency: ESA (European Space Agency) Summary: The JUICE probe will study the Jovian system, focusing on the icy moons of Europa, Callisto and Ganymede, investigating any potential habitable environments.
JUICE will provide the first accurate measurement of the thickness of Europa's icy crust and identify possible landing sites for future missions.
Europa Jupiter System Mission
Launch: TBD Agency: NASA Summary: An extremely ambitious venture by NASA will search for life in the oceans of Europa. A cryobot will melt through the thick ice until it reaches liquid water. At which point it will release a hydrobot to gather information.
The hydrobot may even be equipped with a television camera to send a feed back to Earth. Unfortunately this mission was drawn up before NASA began to endure budget cuts due to the 2008 financial crisis. As a result it has been shelved and pushed well into the future. Instead the ESA will send a sole probe (see above), which will identify possible landing sites for any future venture.
Launch: January 2006 Arrival: February 2007 Agency: NASA Summary: New Horizons took images of Europa during a successful flyby it made in February 2007. These images only confirmed to scientists that the icy moon has a liquid ocean underneath its surface.
Launch: October 1989 Arrival: December 1995 Agency: NASA Summary: Galileo took some spectacular close up images showing that Europa possessed an incredibly complex surface. They showed ice rafts the size of cities that appeared to have broken off then drifted apart and huge cracks on the surface some of which are 12 miles (20 km) wide.
Geologists surmised that these surface features amongst others could only be explained by Europa having a liquid ocean underneath its surface. Galileo also detected an extremely thin atmosphere around the moon.
Voyager 1 and 2
Launch: August-September 1977 Arrival: April-August 1979 Agency: NASA Summary: Both the Voyager spacecraft made successful flybys of Europa sending back intriguing images of the moon. They showed an incredibly smooth icy surface
covered in cracks thousands of kilometers in length.
Pioneer 10 and 11
Launch: March 1972 - April 1973 Arrival: December 1973 - December 1974 Agency: NASA Summary: Both the Pioneer spacecraft made successful flybys of Europa but could only send back fuzzy images of the moon.