JOIN US'Persistent water vapour' found on another one of Jupiter's ice-moons
In a significant development, NASA has detected water vapour on a second of Jupiter's 79 moons, suggesting the abundance of stable water, according to a report by the space agency.
The observations, recorded by the Hubble Space Telescope, have shown the presence of water vapour in only one hemisphere of Europa, which is home to an expansive and potentially life-supporting ocean beneath its surface.
Researchers came to the discovery upon using the same method that led to the discovery of water vapour on Ganymede earlier this year. NASA, in its report, said that the new development would help astronomers better understand the atmosphere of icy moons.
This discovery would also be a foundation for future missions to the Jovian system, the space agency said.
Water vapour on Europa was previously sighted in 2013 in the form of 'plumes erupting through ice', which is to an extent, similar to geysers present on Earth, but can extend to more than 96 kilometres high.
NASA said the results show "similar amounts of water vapor spread over a larger area of Europa in Hubble observations spanning from 1999 to 2015."
"This suggests a long-term presence of a water vapour atmosphere only in Europa's trailing hemisphere – that portion of the moon that is always opposite its direction of motion along its orbit," the report added, saying that researchers were yet to fully understand why the vapour was found only on one hemisphere.
According to Lorenz Roth of the KTH Royal Institute of Technology, Space and Plasma Physics, Sweden, "the detection of a stable water abundance on Europa is a bit more surprising than on Ganymede because Europa's surface temperatures are lower than Ganymede's."
Europa reflects more sunlight compared to Ganymede, which keeps its surface temperature 15.5 degrees Celsius cooler than that of the latter. But observations also show that much like Ganymede, ice water on Europa sublimates, ie. it directly transforms from solid to a gaseous state, skipping the liquid phase.
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