Move over, Europa. It looks as though the most life-friendly habitat ever discovered outside of Earth is Enceladus—Saturn's sixth-largest moon. 
 
 Astrophysicists working with NASA's Saturn sweeping Cassini spacecraft have just announced that Enceladus has a warm ocean at its southern pole with ongoing hydrothermal activity—the first ever discovered outside of Earth. This new research, published in the journal Nature, builds upon last year's discovery of the moon's 6-mile-deep ocean, which is also believed to contain many of the chemicals commonly associated with life. 
 
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 "We now have very strong evidence that there is a hot hydrothermal environment at the base of Enceladus's ocean, perhaps like those where we believe life began on Earth," says Jonathan Lunine, a planetary scientist at Cornell University who works with the Cassini spacecraft but was not involved in the new research. "This is yet another discovery in a series of really remarkable findings that have come one by one, to tell us that this may be the place to go look for life in the outer solar system." 
 
 The clues in the rings 
 
 Sean Hsu, an astrophysicist at the University of Colorado, Boulder who helped to lead the team behind this new discovery, says the discovery happened in what was perhaps a counterintuitive way. He and his colleagues estimated the temperature, salinity, and approximate pH of Enceladus's ocean by studying the dust in Saturn's outermost ring. Really. 
 
 "We've known from quite early on that Enceladus was the source of the material in Saturn's [outermost] ring… based on the ring's composition" Hsu says, "although we didn't know the exact mechanism for the material transfer." But the 2005 discovery of 125-mile-high icy geysers shouted out to scientists how Enceladus flung material skyward. 
 
 Enceladus's heat is created by gravitational friction from the pull of Saturn and its other moons 
 
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 Hsu and his team analyzed a class of dust nanoparticles in this outermost ring. Using Cassini's mass spectrometer tool, they showed that these dust particles were made mostly of silica, and that they were the skeletons of evaporated geyser-flung saltwater. These particles point toward warm waters on Enceladus. 
 
 How? It turns out that the exact size range and makeup of the silicate particles gives the researchers a stunningly accurate blueprint of the conditions that forged them. For example, if Enceladus's ocean were really salty (say, over 4 percent, which is a bit more than Earth's oceans) then the silicate particles would have chemically clumped together, former bigger lumps than were found. 
 
 Here's what these particles revealed about Enceladus's deep ocean: The water is less than 4 percent salinity, has a pH between 8.5 and 10.5 (Earth's ranged between 8.0 to 8.3 before the industrial revolution), and is at least 200 degrees Fahrenheit at hot springs at the bottom of the ocean where the particles are forged. Outside of hydrothermal activity, no other known process could make these uniformly small silica particles, the scientists say. 
 
 Life on Enceladus? 
 
 With temperate, vent-warmed waters that contain nitrogen, methane, carbon dioxide, and various other chemicals required for Earth-like life, Enceladus could very much look like the Lost City hydrothermal field under the Atlantic Ocean—an environment where many scientists believe life first originated on Earth. That's a far cry from the scientific state of affairs 15 years ago, when scientists were sure Enceladus was a lump of boring, uneventful rock. This idea would have been laughable. 
 
 But while Hsu says Enceladus looks tantalizingly habitable, it's not clear whether life could (or does) exist on the moon. "An important consideration is the timescale of the Enceladus's ocean's hydrothermal activities," Hsu says. That is, we just don't know how long Enceladus's hydrothermal activity has gone on. Unlike thermal activity on Earth, which is powered by our hot, churning core, Enceladus's heat is created by gravitational friction from the pull of Saturn and its other moons. 
 
 But Cornell's Lunine says the question as to whether Enceladus's ocean does or doesn't contain life is one we could answer, and soon. All of the new information we're gleaning about Enceladus (and all of Saturn's moons) comes from the Cassini spacecraft, which was developed in the late '80s and early '90s. Despite carrying outdated tech and instruments, it's revolutionizing the way we think about the possibility of life in other parts of the solar system. Lunine is currently working on a proposal for an update to the Cassini mission, using a new spacecraft with both modern day technology and specialized machinery designed to seek out the bio-signs of life. 
 
 "If we go back to Enceladus and build upon the Cassini results with the instruments of today, the short answer is, we know that we'll be able to look for life frozen in the [geyser] particles, and really nail this habitability question," Lunine says. 
 
 Read next: Inside the epic 8-year journey to Ceres ||||| America 
 
 Researchers Think There's A Warm Ocean On Enceladus 
 
 i itoggle caption NASA/JPL/Space Science Institute NASA/JPL/Space Science Institute 
 
 Saturn's moon Enceladus is a mystery. From Earth it looks tiny and cold, and yet it's not a dead hunk of rock. Passing spacecraft see trenches and ridges, similar to Earth's, and in 2005 NASA's Cassini mission spotted ice geysers streaming from its south pole. 
 
 "The moon is actually alive in a sense," says Sean Hsu with the Laboratory for Atmospheric and Space Physics at the University of Colorado at Boulder. 
 
 Beneath the surface, most researchers believe it even has a liquid ocean. Now Hsu and his colleagues have found new evidence that it's a downright balmy ocean. 
 
 i itoggle caption NASA/JPL-Caltech NASA/JPL-Caltech 
 
 The team used the Cassini spacecraft, which orbits Saturn, to detect tiny particles of silica floating in space. It's not sand exactly, but researchers think the particles did come from the bottom of Enceladus' ocean. 
 
 The silica particles could only be made if that ocean were hot. "We think that the temperature at least in some part of the ocean must be higher than 190 degrees Fahrenheit," Hsu says. "If you could swim a little bit further from the really hot part then it could be comfy." 
 
 In fact, 190°F is cooler than many hydrothermal vents at the bottom of Earth's oceans. Hsu says experiments on Earth also suggest the ocean is similar in salinity and pH to oceans here. 
 
 The evidence, published in the journal Nature, is somewhat circumstantial. The theory is that the silica formed and then dissolved in seawater beneath Enceladus' icy crust. It then left the moon through geysers, and filled Saturn's E-ring. From the E-ring, the silica eventually wound up in the giant planet's magnetosphere, which is where Cassini saw it. 
 
 "It's not like they flew through the plumes of Enceladus and measured these particles," says Bill McKinnon, a planetary scientist at Washington University in St. Louis. 
 
 Nevertheless, he and other independent researchers think the hypothesis has a reasonable chance of being right. "It's very hard to make silica in the Saturn system except if you have a warm wet environment," says John Spencer, a researcher at the Southwest Research Institute in Boulder, Colo. Enceladus is the most likely place. 
 
 Why is tiny Enceladus so warm? Spencer suspects it's the gravitational pull of Saturn and some of its other moons. Their attraction could tug the water and rock inside Enceladus, causing it to slosh around and heat up. 
 
 But current models show that gravity alone can't explain the warm oceans, says McKinnon. He thinks something else could be generating that energy. 
 
 "The most exciting possibility is that there's ongoing chemical reactions between the rock inside Enceladus and the water," McKinnon says. 
 
 Those chemical reactions could generate heat, and possibly create conditions for life. Some primitive organisms on our planet live off energy from ocean vents on earth without ever seeing the sun. The energy heating Enceladus' oceans "could be exploited by simple living systems, as happens on the Earth," McKinnon says. 
 
 Right now, such speculation is still pretty far-fetched, but more clues are coming. Later this year, the Cassini spacecraft will skim past Enceladus at a distance of just 30 miles. It should provide one of the best opportunities yet to learn about what's going on inside. ||||| LOS ANGELES (AP) — New research suggests there are hot springs bubbling beneath the icy surface of a tiny Saturn moon. 
 
 This June 28, 2009 image provided by NASA, taken by the international Cassini spacecraft, shows Enceladus, one of Saturn’s moons. A new study published online Wednesday, March 11, 2015, in the journal... (Associated Press) 
 
 If confirmed, it would make the moon Enceladus (ehn-SEHL'-uh-duhs) the only other known body in the solar system besides Earth where hot water and rocks interact underground. 
 
 That activity would make the moon an even more attractive place in the hunt for microbial life. On Earth, scientists have found weird life forms living in hydrothermal vents on the ocean bottom where there's no sunlight. 
 
 The research comes from Cassini, a NASA-European spacecraft that launched in 1997 to explore Saturn and its numerous moons from orbit. It previously uncovered a vast ocean beneath Enceladus and a giant plume of gas and ice streaming from cracks in the south polar region. 
 
 In the latest study, a group led by Cassini team member Sean Hsu of the University of Colorado in Boulder used spacecraft observations and computer modeling to show that the plume is connected to what's happening on the lunar sea floor. 
 
 Judging by their size and makeup, the team believes particles in the plume are the result of hot water coming into contact with rocks on the ocean floor. The resulting mineral-rich water then shoots up through the icy crust and erupts into space in a plume of gas and ice. Some particles settle around Saturn, replenishing its biggest ring. 
 
 The new work also suggests that the ocean is deeper than previous estimates — more than 30 miles deep below the icy crust. It did not provide details on how big the ocean might be, but the Cassini team last year said it could be as big as or even bigger than North America's Lake Superior. 
 
 Cassini should get a better glimpse of the plume later this year when it flies through it, passing within 30 miles above Enceladus' surface. 
 
 The findings were published online Wednesday in the journal Nature. 
 
 In an accompanying editorial, Gabriel Tobie of France's University of Nantes said the environment beneath Enceladus appears similar to the underwater system of hot springs and towering spires nicknamed "Lost City" in the mid-Atlantic. 
 
 It would take future missions such as a lander on the surface of Enceladus to "fully reveal the secrets of its hot springs," he wrote. 
 
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– Thanks to the Cassini spacecraft, we already knew that one of Saturn's moons has a big ocean. Now things have gotten more interesting on Enceladus. It turns out that the ocean is not only warm, it seems to have the same kind of hydrothermal activity going on as oceans on Earth, reports NASA. Bottom line: "This may be the place to go look for life in the outer solar system," says a Cornell scientist not involved with the new study in Nature. That would be microbial life, under conditions similar to those in a network of hot springs under the Atlantic Ocean known as the "Lost City," reports AP. Some scientists think that ancient hydrothermal field yielded the first life on our planet. Some extra-terrestrial sleuthing resulted in the Enceladus discovery: Knowing that a geyser shooting up from the moon's south pole sends up dust particles that settle on Saturn's outer ring, researchers analyzed the outer ring. They discovered that the dust particles were mostly silica, explains Popular Mechanics, and the makeup of that silica yielded details about the ocean in which they were formed. "We think that the temperature at least in some part of the ocean must be higher than 190 degrees Fahrenheit," team member Sean Hsu tells NPR. "If you could swim a little bit further from the really hot part then it could be comfy." The only way to "nail the habitability question" is to send up a new spacecraft to Enceladus with more modern instruments, says the Cornell researcher. He's already working on the proposal. (Read about how Pluto might rejoin the planet club.)