Extra-terrestrial liquid water is water available in its liquid form which is found outside our planet Earth or in space. It is a subject of wide interest among scientists and astronomers. Because it is usually considered as one of the most essential requirements for the existence of any life forms in space. Earth is the only planet in our solar system which is known to have stable bodies of liquid water. Oceanic water covers 71 percent of Earth’s surface, which is the most essential thing to all known life forms in our planet.
Is there Water in Space?
Water Ice in Mars
Water, found on Mars, now exists almost completely as ice. A small amount of water is found as vapor in the atmosphere. The average atmospheric pressure at the surface of Mars is just 600 pascals which is almost 0.6 percent of average sea level pressure in Earth.
Because of that, no large standing bodies of liquid water exist in Mars. Also, the average global temperature in Mars is far too low – approximately 210 K or -63°C. It causes either rapid evaporation or freezing of water. Scientists estimate that reservoirs of ice are still hidden the below the surface of Mars.
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Saline Ocean in Ganymede
Scientists and astronomers are using the Hubble Space Telescope for many years to discover the presence of water in space. In 2015, by using Hubble Telescope, they observed that Ganymede, Jupiter’s largest natural satellite, has a saline ocean buried beneath its icy surface.
Patterns in auroral belts and the changes in the magnetic field observed in Ganymede suggest the presence of a subsurface ocean. Scientists estimate that the ocean is almost 100 km deep and the surface of the ocean lies below a crust of 150 km of ice.
READ ALSO : Is Ganymede bigger than a Planet?
Liquid Ocean below the surface in Europa
According to many scientists and astronomers, a layer of liquid water exists below the surface of Europa, a natural satellite of Jupiter and the sixth-largest moon in our Solar System. Europa is slightly smaller than Earth’s Moon. Heat generated from tidal flexing allows the ocean below the surface to remain liquid.
Many scientists predict that the outer crust of solid ice in Europa is almost 10-30 km thick. This includes a ductile “warm ice” layer. It means that the liquid ocean below the surface could be almost 100 km deep. Thus, the total volume of oceans in Europa becomes 3*1018 m3, which is slightly more than twice the volume of oceans in our planet Earth.
READ ALSO : Could Jupiter become a Star?
Subsurface Ocean in Enceladus
Geysers of water has been found in Enceladus, the sixth-largest moon of Saturn. It was first observed by the Cassini spacecraft in 2005. Later, it was analyzed more deeply in 2008. In 2010-11, scientists confirmed the presence of a subsurface ocean from the gravimetric data.
These geysers form vents near the south pole of Europa which contains small amounts of salt, nitrogen, carbon dioxide and volatile hydrocarbons along with water. Scientists and astronomers predicted that the melting of the ocean water and the formation of the geysers happened due to the tidal flux from Saturn.