Jupiter’s Enigmatic Ocean Moon
Europa is a satellite of Jupiter, about the size of the Earth’s Moon, but very different in appearance. Several lines of evidence suggest that Europa has a vast ocean of liquid water beneath its icy surface, which could contain more water than all of Earth’s oceans combined! Because water is a main requirement for life as we know it, Europa has emerged as one of the best places in our Solar System to search for life beyond Earth.
The relative sizes of the global water content of Earth and Europa. Image credit: NASA.
We have never peeked beneath Europa’s icy shell, but four main lines of evidence have led scientists to conclude that a subsurface ocean is extremely likely:
- Tides caused by the unique orbital configuration of Jupiter’s large moons should generate plenty of heat to maintain a liquid water ocean.
- Observations of Europa’s surface revealed a water-ice composition and geologic features that are best explained if an ocean is present.
- Magnetic measurements showed that a liquid that can conduct electricity, like water, must exist within Europa.
- Measurements of Europa’s density and gravity field constrain the types of materials that could exist within Europa. Including a liquid water layer in models of Europa’s interior structure provides the best fit to the data.
Most of the data we have was acquired by the Voyager spacecraft in the 1970’s and the Galileo spacecraft in the 1990’s. There is currently no funded NASA mission to the Jupiter system, and there won’t be without your help.
Continue reading: The Galilean Satellites
Image credit for top image: NASA
