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Saturday, 22 April 2017

Forget Life on Mars - It's Life on Enceladus


Scientists have found hydrogen gas on the Saturn moon Enceladus, coming from its subsurface ocean. This shows similarity to our planet's hydrothermal ocean vents which support life on the seafloor, indicating that Enceladus could be habitable for microbes.


Scientists from Southwest Research Institute (SwRI) analysed data from the NASA spacecraft, Cassini, which dived into a plume of spray coming from the cracks in the ice-covered moon's, south polar region in 2015. The presence of molecular hydrogen and carbon dioxide was detected and is believed to come from chemical reactions between the moon's hot core and its subsurface ocean. 

During Cassini’s deepest dive through the Enceladus plume, SwRI scientists discovered hydrogen gas in the material erupting from the Saturnian moon. This discovery provides further evidence for hydrothermal activity (illustrated here) and heightens the possibility that the ocean of Enceladus could have conditions suitable for microbial life. From http://www.swri.org/9what/releases/2017/enceladus-saturn-moon-habitable.htm#.WPTxUdIrLIU


On Earth's seafloor, hydrothermal vents support a huge amount of life including whole ecosystems because of the mineral-rich fluid they produce. Microbes use hydrogen as a source of energy in a process called methanogenesis which scientists believe is an indicator of life on other planets. 

The presence of hydrogen in the plume on Enceladus indicates that the same energy source for microbes is in the subsurface ocean - although no microbial life has been found yet. 

"The amount of molecular hydrogen we detected is high enough to support microbes similar to those that live near hydrothermal vents on Earth," said SwRI's Dr Christopher Glein a pioneer of extraterrestrial chemical oceanography. 

To be able to search for hydrogen from Enceladus, the spacecraft Cassini flew close to the moon's surface and a new operation mode was created for one of the spacecraft's instruments. 

The scientists behind the study also considered if the hydrogen was from other sources, like the subsurface ocean or in a reservoir in the icy surface of the moon, however, the analysis from the instruments showed that it indeed was from processes during the formation of the moon or other processes on its surface or interior. "Everything indicates that the hydrogen originates in the moon's rocky core," said Dr Hunter Waite of SwRI and principle investigator.

Ok so it's not as exciting as finding a planet full of life, but it is pretty exciting that this moon could hold the potential for life.

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Original Journal Article: 
Cassini finds molecular hydrogen in the Enceladus plume: Evidence for hydrothermal processes
J. Hunter Waite, Christopher R. Glein, Rebecca S. Perryman, Ben D. Teolis, Brian A. Magee, Greg Miller, Jacob Grimes, Mark E. Perry, Kelly E. Miller, Alexis Bouquet, Jonathan I. Lunine, Tim Brockwell, Scott J. Bolton
Science  14 Apr 2017: Vol. 356, Issue 6334, pp. 155-159


"Cassini detects hydrothermal processes on one of Saturn's moons"