{"id":15971,"date":"2015-10-29T00:36:46","date_gmt":"2015-10-28T16:36:46","guid":{"rendered":"https:\/\/wp-productionenv-bjg9h2g2bgg5b8aa.southeastasia-01.azurewebsites.net\/news\/cassini-survives-daring-flight-through-plumes-of-enceladus\/"},"modified":"2015-10-29T00:36:46","modified_gmt":"2015-10-28T16:36:46","slug":"cassini-survives-daring-flight-through-plumes-of-enceladus","status":"publish","type":"post","link":"https:\/\/starpath.global\/news\/cassini-survives-daring-flight-through-plumes-of-enceladus\/","title":{"rendered":"Cassini survives daring flight through plumes of Enceladus"},"content":{"rendered":"<p><strong><em>Updated after&nbsp;confirmation of Wednesday\u2019s flyby.<\/em><\/strong><\/p>\n<p><iframe loading=\"lazy\" width=\"678\" height=\"381\" src=\"https:\/\/www.youtube.com\/embed\/BZ1KowQXc3Y?feature=oembed\" frameborder=\"0\" allowfullscreen=\"\"><\/iframe><\/p>\n<p>NASA\u2019s Cassini spacecraft radioed home Wednesday after a high-speed dash through the wispy fountains of Saturn\u2019s moon Enceladus, sampling particles that hold telltale hints whether alien life could survive somewhere in the depths of a vast global ocean hidden beneath a crust of rumpled ice.<\/p>\n<p>Scientists believe the material seeping into space through vents or fractures scattered across Enceladus\u2019 south pole comes directly from the underground sea, offering a glimpse into the moon\u2019s interior, where conditions might be ripe to host microbes.<\/p>\n<p>Bolting by Enceladus at 19,000 mph, the plutonium-powered Cassini space probe was expected to only pass through the icy plumes for a few tens of seconds, scientists said, but the orbiter was programmed to execute a tightly-choreographed observation sequence to measure the chemical constituents of the eruption cloud and capture a series of images.<\/p>\n<p>Pictures from the flyby are expected in 24 to 48 hours, NASA said late Wednesday.<\/p>\n<p>\u201cWe\u2019re going to be scraping over the south pole (of Enceladus) at around 19,000 mph, just 30 miles above the surface, and we\u2019re going to go right through the plume,\u201d said Earl Maize, Cassini\u2019s project manager at the Jet Propulsion Laboratory in Pasadena, California.<\/p>\n<p>The flyby was the the deepest dive through the icy plumes since Cassini discovered the geyser-like features over Enceladus\u2019 south pole in 2005. The plumes originate near long, sinuous fissures scientists have dubbed tiger stripes. The fractures are conduits through which material from the underground ocean streams into space.<\/p>\n<p>Wednesday\u2019s encounter with Enceladus was Cassini\u2019s 21st passage near the icy moon. About the size of the U.S. state of Arizona, Enceladus\u2019 frozen exterior makes it one of the brightest objects in the solar system.<\/p>\n<p>\u201cWe learned that just like Jupiter\u2019s larger moon Europa, there is a global liquid water ocean under Enceladus\u2019 icy crust, and we also discovered evidence that there is hydrothermal activity, reactions between hot rock and liquid water, occurring inside Enceladus at the bottom of that ocean,\u201d said Curt Niebur, Cassini\u2019s program scientist at NASA Headquarters in Washington.<\/p>\n<p>Controlled from JPL, Cassini is in its final two years orbiting Saturn. The spacecraft, which NASA dispatched from Earth in 1997, is running low on maneuvering fuel after 11 years circling the giant ringed planet.<\/p>\n<p>NASA has extended the multibillion-dollar mission several times, giving Cassini dozens of flybys of Saturn\u2019s largest moon Titan, a world bigger than Mercury shrouded in hazes and harboring seas and rivers of liquid hydrocarbons. Cassini dropped a short-lived European-built lander on Titan in 2005.<\/p>\n<p>Titan still holds much interest among planetary scientists, who consider it among the most Earth-like worlds in the solar system. But Enceladus turned out to be another star of Cassini\u2019s mission.<\/p>\n<figure id=\"attachment_10084\" aria-describedby=\"caption-attachment-10084\" style=\"width: 640px\" class=\"wp-caption alignnone\"><img fetchpriority=\"high\" decoding=\"async\" class=\"size-full wp-image-10084\" src=\"http:\/\/spaceflightnow.com\/wp-content\/uploads\/2015\/10\/pia12733-640.jpg\" alt=\"At least four distinct plumes of water ice spew out from the south polar region of Saturn's moon Enceladus in this dramatically illuminated image from earlier in Cassini's mission. Image credit: NASA\/JPL\/Space Science Institute\" width=\"640\" height=\"350\" srcset=\"https:\/\/spaceflightnow.com\/wp-content\/uploads\/2015\/10\/pia12733-640.jpg 640w, https:\/\/spaceflightnow.com\/wp-content\/uploads\/2015\/10\/pia12733-640-300x164.jpg 300w\" sizes=\"(max-width: 640px) 100vw, 640px\"><figcaption id=\"caption-attachment-10084\" class=\"wp-caption-text\">At least four distinct plumes of water ice spew out from the south polar region of Saturn\u2019s moon Enceladus in this dramatically illuminated image from earlier in Cassini\u2019s mission. Credit: NASA\/JPL\/Space Science Institute<\/figcaption><\/figure>\n<p>\u201cEnceladus is not just an ocean world,\u201d Niebur told reporters Monday. \u201cIt\u2019s a world that might provide a habitable environment for life as we know it, and while the Cassini spacecraft does not have the instruments needed to detect life, it does have the instruments that can tell us about the characteristics of that ocean, and it is those characteristics that control \u2026 whether or not life on Enceladus is even a remote possibility.\u201d<\/p>\n<p>With a closer look at the source of the plumes, scientists hope to learn whether their source is in discrete nozzles like geysers on Earth, or if the eruptions come from long cracks in Enceladus, resulting in a curtain of material escaping the moon and populating Saturn\u2019s orbit.<\/p>\n<p>Cassini\u2019s cameras peered toward Enceladus as the spacecraft streaks past the moon, attempting to capture views of the surface fractures \u2014 or tiger stripes \u2014 where the plumes appear out of the crust. The region was in darkness at the time of the flyby, but reflected sunlight from Saturn \u2014 nicknamed \u201cSaturnshine\u201d by scientists \u2014 offered dim illumination.<\/p>\n<p>The raw views will be smeared due to Cassini\u2019s blazing speed, but computer processing on the ground should sharpen the images and yield a high-resolution look at the tiger stripes.<\/p>\n<p>Jonathan Lunine, a member of Cassini\u2019s science team from Cornell University, said there is \u201calmost incontrovertible evidence\u201d of a global ocean lurking inside Enceladus. Cassini has already measured stuff from the subsurface ocean, Lunine said, but Wednesday\u2019s plow through the plumes should give the spacecraft a bigger taste.<\/p>\n<p>\u201cWe\u2019re also quite sure that the larger grains that Cassini has sampled, the ones with the salts present, those are actually frozen sea water,\u201d Lunine said in an interview with Spaceflight Now. \u201cThey\u2019re coming out of the ocean and freezing with the salt trapped in it, so we\u2019re then essentially sampling this subterranean ocean.\u201d<\/p>\n<hr>\n<h6>Spaceflight Now members can read a transcript of our full interview with&nbsp;Jonathan Lunine.&nbsp;Become a member today and support our coverage.<\/h6>\n<hr>\n<h5><\/h5>\n<p>Sensors on Cassini were also supposed to hunt for organics more complex than the carbon-bearing molecules found on previous visits to Enceladus.<\/p>\n<p>\u201cWe\u2019ve seen organics, we\u2019ve seen methane and carbon dioxide, and a number of key ingredients, and in this case with our much deeper dive through the plume, we\u2019ll have the chance to sample potentially larger particles and a greater density of both the gas and the particles,\u201d said Linda Spilker, Cassini\u2019s project scientist at JPL, before the Enceladus flyby. \u201cWe might find new organics that we haven\u2019t seen previously just at the limits of our detection.\u201d<\/p>\n<figure id=\"attachment_10086\" aria-describedby=\"caption-attachment-10086\" style=\"width: 620px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-10086\" src=\"http:\/\/spaceflightnow.com\/wp-content\/uploads\/2015\/10\/e21_groundtrack.png\" alt=\"This map projection of Enceladus' southern polar region shows the ground track to be covered by Cassini's Oct. 28 flyby. The circles represent regions where the spacecraft's cameras will attempt to image vents near the moon's so-called tiger stripe features. Credit: NASA\/JPL-Caltech\" width=\"620\" height=\"618\" srcset=\"https:\/\/spaceflightnow.com\/wp-content\/uploads\/2015\/10\/e21_groundtrack.png 620w, https:\/\/spaceflightnow.com\/wp-content\/uploads\/2015\/10\/e21_groundtrack-150x150.png 150w, https:\/\/spaceflightnow.com\/wp-content\/uploads\/2015\/10\/e21_groundtrack-300x300.png 300w\" sizes=\"(max-width: 620px) 100vw, 620px\"><figcaption id=\"caption-attachment-10086\" class=\"wp-caption-text\">This map projection of Enceladus\u2019 southern polar region shows the ground track to be covered by Cassini\u2019s Oct. 28 flyby. The circles represent regions where the spacecraft\u2019s cameras will attempt to image vents near the moon\u2019s so-called tiger stripe features. Credit: NASA\/JPL-Caltech<\/figcaption><\/figure>\n<p>Luanne said the spacecraft\u2019s spectrometers were built with Titan in mind, not Enceladus, and are rooted in technology from the 1980s.<\/p>\n<p>Lunine is eager to see if the probe\u2019s ion and neutral mass spectrometer detects molecular hydrogen embedded in the plumes.<\/p>\n<p>A positive detection of hydrogen would bolster evidence for hydrothermal vents at the sea floor. Lunine said the interaction of hot water and rock at the base of the subsurface ocean should produce molecular hydrogen, but it is still a question whether the hydrogen signature will register with Cassini.<\/p>\n<p>Deep vents on Enceladus\u2019 sea floor could provide an environment where microbes could thrive as they do at the bottom of Earth\u2019s oceans, according to scientists.<\/p>\n<p>\u201cThe amount of hydrogen emission will reveal for us how much hydrothermal activity is actually occurring on that sea floor with implications for the amount of energy thats available,\u201d Spilker said. \u201cEnergy is a key ingredient for habitability on Enceladus.\u201d<\/p>\n<p>Even if Cassini does not find molecular hydrogen, it does not rule out hydrothermal activity, Lunine said.<\/p>\n<p>\u201cHydrogen is very reactive, and if it\u2019s made at the base of the ocean \u2014 if indeed it is made there \u2014 it\u2019s quite possible that it reacts with some other molecules or possibly even gets eaten up by life if life is present,\u201d Lunine said in an interview with Spaceflight Now. \u201cEven in the case of the Earth, one often doesn\u2019t measure as much hydrogen at these tantalizing hydrothermal systems as one would expect. So we\u2019ll look for it.\u201d<\/p>\n<p>But Lunine\u2019s chief concern was Cassini surviving Wednesday\u2019s flyby.<\/p>\n<p>\u201cNo. 1, I\u2019m looking for is Cassini safely coming out the other side because we\u2019ve got many other exciting things we want Cassini to do,\u201d Lunine said.<\/p>\n<figure id=\"attachment_10087\" aria-describedby=\"caption-attachment-10087\" style=\"width: 621px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\" wp-image-10087\" src=\"http:\/\/spaceflightnow.com\/wp-content\/uploads\/2015\/10\/467733main_plumes.jpg\" alt=\"Lunine's mission concept called Enceladus Life Finder would send a spacecraft through Enceladus' plumes, much like Cassini's flybys, but with modernized instrumentation capable of detecting life. Credit: NASA\/JPL\/SSI \" width=\"621\" height=\"384\" srcset=\"https:\/\/spaceflightnow.com\/wp-content\/uploads\/2015\/10\/467733main_plumes.jpg 1580w, https:\/\/spaceflightnow.com\/wp-content\/uploads\/2015\/10\/467733main_plumes-300x186.jpg 300w, https:\/\/spaceflightnow.com\/wp-content\/uploads\/2015\/10\/467733main_plumes-768x475.jpg 768w, https:\/\/spaceflightnow.com\/wp-content\/uploads\/2015\/10\/467733main_plumes-1024x633.jpg 1024w\" sizes=\"auto, (max-width: 621px) 100vw, 621px\"><figcaption id=\"caption-attachment-10087\" class=\"wp-caption-text\">Lunine\u2019s mission concept called Enceladus Life Finder would send a spacecraft through Enceladus\u2019 plumes, much like Cassini\u2019s flybys, but with modernized instrumentation capable of detecting life. Credit: NASA\/JPL\/SSI<\/figcaption><\/figure>\n<p>There was a slight risk with the encounter, Maize said. He described the density of the plume as like steam or smoke, but any collision with a large particle at Cassini\u2019s speed could spell disaster.<\/p>\n<p>\u201cWe have flown through the plumes before at a higher altitude (where it is) not quite so dense, so this is a little bit riskier, but not that much,\u201d Maize said. \u201cWe feel like we\u2019re taking a very prudent approach at this point in the mission. We still have a couple of years left and exciting stuff still to do, so we\u2019re not going to risk everything on this one flyby.\u201d<\/p>\n<p>Wednesday\u2019s flyby was the penultimate time scientists will get an up-close look at Enceladus for more than a decade, and potentially years longer, until a new mission is sent with a modern payload.<\/p>\n<p>\u201cI think we\u2019ll get superb data, and I\u2019m looking forward to discovering some new molecules in the plume, and some new things about the icy grains that are there,\u201d Lunine said. \u201cIt\u2019s going to be really high quality data, better than we\u2019ve gotten before.<\/p>\n<p>\u201cBut we also know that this is going to create a new set of questions, as any good data set does,\u201d Lunine said. \u201cWe\u2019re not going to be able to go back with Cassini and say we\u2019re going to do another plume passage to address those questions, so that\u2019s a little tough.\u201d<\/p>\n<p>One more swing by Enceladus is scheduled for Dec. 19 \u2014 at a more distant range than Wednesday\u2019s visit \u2014 then Cassini\u2019s trajectory will take the spacecraft near Titan for a final series of flybys there, before looping inside Saturn\u2019s rings in the final phase of the mission.<\/p>\n<p>Ground controllers will oversee Cassini\u2019s plunge into Saturn\u2019s atmosphere in September 2017 to conclude the mission nearly 20 years after its launch.<\/p>\n<p>Lunine, who leads Cornell\u2019s Center for Radiophysics and Space Research, said he has worked on the Cassini project more than 30 years.<\/p>\n<p>\u201cLast week, we just celebrated the 25th anniversary \u2014 the silver anniversary \u2014 of the start of the mission in 1990,\u201d Lunine said. \u201cI was involved in preliminary studies throught the 1980s. I like to tell people I was engaged to Cassini for six years, and then married to it for 25 years. After that, it\u2019s going to be hard to let it go.\u201d<\/p>\n<p><b><i>Email the author.<\/i><\/b><\/p>\n<p><em><strong>Follow Stephen Clark on Twitter: @StephenClark1.<\/strong><\/em><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Updated after&nbsp;confirmation of Wednesday\u2019s flyby. NASA\u2019s Cassini spacecraft radioed home Wednesday after a high-speed dash through the wispy fountains of Saturn\u2019s moon Enceladus, sampling particles that hold telltale hints whether alien life could survive somewhere in the depths of a vast global ocean hidden beneath a crust of rumpled ice. Scientists believe the material seeping [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"inline_featured_image":false,"footnotes":"","_links_to":"","_links_to_target":""},"categories":[2],"tags":[2394,1559,1562],"class_list":["post-15971","post","type-post","status-publish","format-standard","hentry","category-news","tag-cassini","tag-enceladus","tag-saturn"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/15971"}],"collection":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/comments?post=15971"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/15971\/revisions"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=15971"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=15971"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=15971"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}