Conditions for life on Saturn moon
US Cassini detected hydrogen in a steam plume emanating cracks in the thick layer of ice enveloping Enceladus, a small moon of Saturn, which can be explained by hydrothermal activity conducive to the existence of life.
According to scientists whose discovery was reported Thursday in the journal Science, “hydrothermal reactions between hot rocks and the ocean lying beneath the frozen surface of the moon is the only plausible source of the hydrogen.”
“Although we have not detected life, we found a power source of life,” said Hunter Waite of the Southwest Research Institute in San Antonio (Texas). “It’s like a candy store for microbes.”
On Earth, this process provides energy to the ecosystems that thrive near hydrothermal vents on the ocean floor where there is volcanic activity.
“This is the first time we identify a place gathering the ingredients for a habitable environment,” pointed Thomas Zurbuchen, deputy head of scientific missions of NASA, at a press conference.
“These results show that various studies conducted by the agency bring us closer when we can answer the question of whether or not we are alone in the universe,” he noted.
Cassini’s instruments detected the molecular hydrogen in October 2015, when the probe approached closer to the surface of Enceladus –in 50 kilomètres– to cross a huge geyser in the south polar region.
Researchers have determined that the vapor and particles, very largely composed of water, contained inter alia up to 1.4% hydrogen and carbon dioxide.
These are essential to methanogenesis, a chemical reaction on Earth for microbes to live in the deep ocean as the sun’s rays can not reach.
According to scientific estimates, Enceladus has the energy equivalent of 300 pizzas per hour which would be more than enough to support a possible microbial life. “This is the first time we are able to count the calories of an extraterrestrial ocean,” noted Christopher Glein, geochemist from the Institute of Texan research.
“This finding is an important step to assess the habitability of Enceladus,” said in an article accompanying the study, Jeffrey Seewald, a scientist at the Woods Hole Oceanographic Institution.
“This indicates that there is the chemical potential for microbial life,” said Hunter Waite.
As we know, the origin of life requires three main elements: liquid water, an energy source for metabolism of organisms and chemical ingredients particularly carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur, said the scientists.
The data collected by Cassini Enceladus show almost has all the ingredients needed for livability.
Cassini had collected elements indicating the presence of a large ocean under a thick layer of ice at the bottom of which is a bedrock.
Furthermore, also study published Thursday in the Astrophysical Journal Letters reveals that thanks to the US Hubble Space Telescope, scientists have observed in 2016 what appears to be a geyser a hundred kilometers high in Europe, one of the largest Jupiter’s moons, which also has an ocean under a layer of ice.
Hubble has captured images of a jet of steam at the same place in 2014, but which was only 50 kilometers away.
This observation confirms the existence of this phenomenon on the Jovian moon that appear intermittently in the same region.
These discoveries on Enceladus and Europe will help NASA prepare the Clipper exploration mission in Europe, which will be launched in the 2020s.
The mission Cassini, orbiting Saturn since 2004, is nearing its end. The probe will initiate the maneuvers that will plunge into the atmosphere of the gas giant planet on 15 September.
It must make April 26 the first descent into uncharted space of 2,400 kilometers between Saturn’s rings, NASA said.