The quest for alien life within our solar system has been imbued with newfound enthusiasm by an astounding discovery on Saturn’s moon, Enceladus.
An international team of researchers, featuring Dr. Christopher Glein from the Southwest Research Institute, has unearthed a piece of crucial evidence hinting at the existence of an essential life element beneath the icy shell of Saturn’s moon, Enceladus.
Data retrieved from NASA’s Cassini mission has played an instrumental role in this discovery. The team has found direct traces of phosphorus, a vital life building block, in the form of phosphates in the subsurface ocean of Enceladus.
Cassini, a space probe launched to scrutinize Saturn and its extensive system of moons and rings, has delivered crucial insights over its 13-year journey.
Dr. Glein, a renowned figure in extraterrestrial oceanography, expressed his excitement over this groundbreaking find.
“In 2020 (published in 2022), we used geochemical modeling to predict that phosphorus should be abundant in Enceladus’ ocean,” he said. “Now, we have found abundant phosphorus in plume ice samples spraying out of the subsurface ocean.”
Cassini’s extensive exploration led to the remarkable discovery of liquid water beneath Enceladus’s icy exterior. The spacecraft analyzed plume samples containing ice grains and gases escaping into space from the moon’s frosty surface. The data analysis revealed sodium phosphates within salt-rich ice grains, suggesting that phosphates are readily available in the moon’s subsurface ocean.
The existence of phosphorus in the form of phosphates is a prerequisite for all known forms of life. The building of DNA and RNA, essential components of cell membranes, energy-carrying molecules, the human and animal structures of bones and teeth, and even the sea’s diverse microbiome of plankton, all rely on phosphates.
Glein shed light on the astonishing concentration of phosphates within Enceladus’s waters. “We found phosphate concentrations at least 100 times higher in the moon’s plume-forming ocean waters than in Earth’s oceans,” he said.
“Using a model to predict the presence of phosphate is one thing, but actually finding the evidence for phosphate is incredibly exciting. This is a stunning result for astrobiology and a major step forward in the search for life beyond Earth.”
In the last quarter of a century, scientists have acknowledged that worlds sheltering oceans beneath an icy layer are abundant within our solar system. These include distant bodies like Pluto and the icy moons of the giant planets such as Europa, Titan, and Saturn’s moon, Enceladus.
Unlike Earth, which has to maintain a precise distance from the sun to sustain surface liquid water, these ice-covered ocean worlds can exist over a wider range of distances, thus potentially increasing the habitable world count in the galaxy.
Glein also hinted at the higher phosphate concentrations on such icy worlds. “Geochemical experiments and modeling demonstrate that such high phosphate concentrations result from enhanced phosphate mineral solubility, in Enceladus and possibly other icy ocean worlds in the solar system beyond Jupiter,” he said.
“With this finding, the ocean of Enceladus is now known to satisfy what is generally considered to be the strictest requirement for life. The next step is clear – we need to go back to Enceladus to see if the habitable ocean is actually inhabited.”
The research, published in the journal Nature as “Detection of Phosphates Originating from Enceladus’ Ocean,” includes contributions from scientists across ten global institutions. Frank Postberg from the Institut für Geologische Wissenschaften, Freie Universität Berlin, Germany, leads the author list, while Glein was the principal investigator from the U.S.
The Cassini mission, the source of this fascinating discovery, stands as a testament to the essential role of long-term space exploration projects. Launched in 1997, the probe provided scientists with an extended 13-year observation window into Saturn’s mysterious system, teeming with rings and moons.
The detection of sodium phosphates within salt-rich ice grains was achieved through Cassini’s Cosmic Dust Analyzer. This sophisticated instrument was pivotal in establishing the possibility that phosphorus is readily available in Enceladus’ ocean as phosphates. It’s an impressive example of how human-made technology is capable of extending our reach and understanding to distant celestial bodies.
The presence of phosphates in the water plumes of Enceladus has wide-reaching implications. Phosphorus, in the form of phosphates, plays a central role in supporting life. This essential ingredient forms the backbone of DNA and RNA, structures critical for life as we understand it.
It also plays a crucial role in the energy transfer within cells and helps form the structure of cell membranes. The sea’s diverse microbiome of plankton, the foundations of bones and teeth in humans and animals, and other life-supporting structures also rely on phosphates.
The findings are incredibly significant. Glein noted that the phosphate concentrations in Enceladus’s waters were at least 100 times higher than in Earth’s oceans. “This is a stunning result for astrobiology and a major step forward in the search for life beyond Earth,” he exclaimed, emphasizing the magnitude of the discovery.
This new understanding could reshape our view of habitable worlds. The research, which builds on the realization that icy bodies housing subsurface oceans are more common than previously thought, suggests that there could be many more potential habitats for life in the universe. This is because such “ocean worlds,” unlike Earth, can exist over a wider range of distances from their host stars, making them potentially more abundant.
As for what comes next, the scientists are clear about their goals. “The next step is clear – we need to go back to Enceladus to see if the habitable ocean is actually inhabited,” concluded Glein.
Indeed, these remarkable findings have only intensified the desire and drive for further exploration, advancing our quest to understand the universe and our place within it. The future of astrobiology is shining brighter than ever.
Enceladus, one of Saturn’s 145 known moons, has piqued the interest of astronomers and astrobiologists alike due to its fascinating geological activity and the potential for extraterrestrial life.
Named after a Giant in Greek mythology, Enceladus is a relatively small celestial body, approximately 500 kilometers in diameter, making it about one-seventh the size of Earth’s Moon. Despite its small size, Enceladus has a tremendous impact on its surroundings, mainly contributing to Saturn’s E ring, the planet’s second outermost ring.
Here’s an overview of what we know about Enceladus:
Enceladus is one of the most reflective bodies in the solar system due to its surface being mostly covered in fresh, clean ice. It reflects almost 100% of the sunlight that strikes it. The surface of Enceladus is largely composed of water ice, which makes it one of the brightest objects in the solar system.
The surface has a mix of old, heavily cratered regions and smooth, young terrains. The moon’s south polar region is particularly intriguing with its “tiger stripes” or “sulci” – four roughly parallel, deep blue fractures that spew out water-rich plumes.
Enceladus is known for its active geysers erupting from the “tiger stripes” in the south polar region. These eruptions are a form of cryovolcanism, where instead of molten rock, the eruptions consist of water, ice, and vapors such as ammonia and carbon dioxide. The materials ejected from the plumes feed Saturn’s E ring.
Perhaps the most exciting discovery about Enceladus is the indication of a subsurface ocean of liquid water. The detection of salt in the plumes indicates the water is in contact with the moon’s rocky mantle, making it a potential place for chemical reactions that could support life. The ocean is believed to be global and lies beneath a shell of ice, possibly up to several kilometers thick.
The discovery of a subsurface ocean along with the detection of organic compounds and various salts has made Enceladus a potential habitat for extraterrestrial life. The discovery of silica nanoparticles also suggests that there might be hydrothermal activity on the seafloor of Enceladus, another encouraging sign for life. The recent finding of phosphorus (as phosphates) in the plume samples, another key ingredient for life, has fueled the hope of finding extraterrestrial life.
Enceladus has been explored by multiple space missions. The two Voyager spacecraft flew by it in the 1980s, but it was NASA’s Cassini spacecraft, which arrived at Saturn in 2004, that made the most detailed observations of Enceladus. It was Cassini that discovered the moon’s geysers and the salty subsurface ocean.
Future missions to Enceladus are being considered, including ones that could sample the plumes for signs of life. As of my knowledge cutoff in September 2021, no such missions have been officially planned or launched yet. The potential habitability of Enceladus is an ongoing subject of research in the scientific community.