NASA scientists, using data from the Cassini spacecraft, have found evidence of hydrothermal vents on Eceladus, the sixth largest moon out of more than 60 orbiting Saturn and one of the most studied cosmic objects in our solar system due to its subterranean oceans. These vents appear to be similar to those on Earth, where scientists believe life on this planet originated.
Scientists are hoping these vents may currently host some form of microbial alien life, a discovery that would shake the scientific world to its core were it ever confirmed. The finding suggests that Enceladus should be a key focus in coming NASA research missions.
The full statement from the Southwest Research Institute is below.
Scientists from Southwest Research Institute (SwRI) have discovered hydrogen gas in the plume of material erupting from Saturn’s moon Enceladus. Analysis of data from NASA’s Cassini spacecraft indicates that the hydrogen is best explained by chemical reactions between the moon’s rocky core and warm water from its subsurface ocean. The SwRI-led team’s discovery suggests that Enceladus’ ocean floor could include features analogous to hydrothermal vents on Earth, which are known to support life on the seafloor.
“Hydrogen is a source of chemical energy for microbes that live in the Earth’s oceans near hydrothermal vents,” said SwRI’s Dr. Hunter Waite, principal investigator of Cassini’s Ion Neutral Mass Spectrometer (INMS). “Our results indicate the same chemical energy source is present in the ocean of Enceladus. We have not found evidence of the presence of microbial life in the ocean of Enceladus, but the discovery of hydrogen gas and the evidence for ongoing hydrothermal activity offer a tantalizing suggestion that habitable conditions could exist beneath the moon’s icy crust.”
Waite is the lead author of “Cassini Finds Molecular Hydrogen in the Enceladus Plume: Evidence for Hydrothermal Processes,” published in the April 14, 2017, issue of the journal Science.
On the Earth’s ocean floor, hydrothermal vents emit hot, mineral-laden fluid, allowing unique ecosystems teeming with unusual creatures to thrive. Microbes that convert mineral-laden fluid into metabolic energy make these ecosystems possible.
“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 co-author on the paper and a pioneer of extraterrestrial chemical oceanography. “If similar organisms are present in Enceladus, they could ‘burn’ the hydrogen to obtain energy for chemosynthesis, which could conceivably serve as a foundation for a larger ecosystem.”
During Cassini’s close flyby of Enceladus on Oct. 28, 2015, INMS detected molecular hydrogen as the spacecraft flew through the plume of gas and ice grains spewing from cracks on the surface. Previous flybys provided evidence for a global subsurface ocean residing above a rocky core. Molecular hydrogen in the plumes could serve as a marker for hydrothermal processes, which could provide the chemical energy necessary to support life. To search for hydrogen specifically native to Enceladus, the spacecraft flew particularly close to the surface and operated INMS in a specific mode to minimize and quantify any spurious sources.
“We developed new operations methods for INMS for Cassini’s final flight through Enceladus’ plume,” said SwRI’s Rebecca Perryman, the INMS operations technical lead. “We conducted extensive simulations, data analyses, and laboratory tests to identify background sources of hydrogen, allowing us to quantify just how much molecular hydrogen was truly originating from Enceladus itself.”
Scientists also considered other sources of hydrogen from the moon itself, such as a preexisting reservoir in the ice shell or global ocean. Analysis determined that it was unlikely that the observed hydrogen was acquired during the formation of Enceladus or from other processes on the moon’s surface or in the interior.
“Everything indicates that the hydrogen originates in the moon’s rocky core,” Waite said. “We considered various ways hydrogen could leach from the rock and found that the most plausible source is ongoing hydrothermal reactions of rock containing reduced minerals and organic materials.”
A recent NASA statement on the subject is below.
Two veteran NASA missions are providing new details about icy, ocean-bearing moons of Jupiter and Saturn, further heightening the scientific interest of these and other “ocean worlds” in our solar system and beyond. The findings are presented in papers published Thursday by researchers with NASA’s Cassini mission to Saturn and Hubble Space Telescope.
In the papers, Cassini scientists announce that a form of chemical energy that life can feed on appears to exist on Saturn’s moon Enceladus, and Hubble researchers report additional evidence of plumes erupting from Jupiter’s moon Europa.
“This is the closest we’ve come, so far, to identifying a place with some of the ingredients needed for a habitable environment,” said Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate at Headquarters in Washington. “These results demonstrate the interconnected nature of NASA’s science missions that are getting us closer to answering whether we are indeed alone or not.”
The paper from researchers with the Cassini mission, published in the journal Science, indicates hydrogen gas, which could potentially provide a chemical energy source for life, is pouring into the subsurface ocean of Enceladus from hydrothermal activity on the seafloor.
The presence of ample hydrogen in the moon’s ocean means that microbes – if any exist there – could use it to obtain energy by combining the hydrogen with carbon dioxide dissolved in the water. This chemical reaction, known as “methanogenesis” because it produces methane as a byproduct, is at the root of the tree of life on Earth, and could even have been critical to the origin of life on our planet.
Life as we know it requires three primary ingredients: liquid water; a source of energy for metabolism; and the right chemical ingredients, primarily carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur. With this finding, Cassini has shown that Enceladus – a small, icy moon a billion miles farther from the sun than Earth – has nearly all of these ingredients for habitability. Cassini has not yet shown phosphorus and sulfur are present in the ocean, but scientists suspect them to be, since the rocky core of Enceladus is thought to be chemically similar to meteorites that contain the two elements.
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