{"id":19603,"date":"2015-09-28T17:03:28","date_gmt":"2015-09-28T09:03:28","guid":{"rendered":"https:\/\/wp-productionenv-bjg9h2g2bgg5b8aa.southeastasia-01.azurewebsites.net\/news\/mars-mystery-solved-dark-streaks-linked-to-salty-water-trails\/"},"modified":"2015-09-28T17:03:28","modified_gmt":"2015-09-28T09:03:28","slug":"mars-mystery-solved-dark-streaks-linked-to-salty-water-trails","status":"publish","type":"post","link":"https:\/\/starpath.global\/news\/mars-mystery-solved-dark-streaks-linked-to-salty-water-trails\/","title":{"rendered":"Mars mystery solved? Dark streaks linked to salty water trails"},"content":{"rendered":"
\"Recurring
These dark streaks, shown flowing downhill in a false-color image from NASA\u2019s Mars Reconnaissance Orbiter, are inferred to have been formed by contemporary flowing water. (Credit: NASA \/ JPL \/ Univ. of Arizona)<\/figcaption><\/figure>\n

For years, scientists have puzzled over dark streaks that appear and disappear on the surface of Mars \u2013 and now they\u2019re confident enough to assert that the streaks are caused by trickles of salty water.<\/p>\n

Their findings, published Monday in Nature Geoscience, serve as the best evidence yet that liquid water still occasionally flows on the Red Planet. The research is likely to spark a new wave of speculation about life on Mars \u2013 but it\u2019s not likely to justify the breathless reports that circulated in advance of the study\u2019s release.<\/p>\n

\u201cHas NASA found life on Mars?\u201d one headline asked over the weekend. The short answer is no. Nevertheless, NASA thought enough of the study to call it a \u201cmajor science finding\u201d and schedule a news briefing about it.<\/p>\n

John Grunsfeld, NASA\u2019s associate administrator for space science, said the results make it \u201ceven more imperative that we send astrobiologists and planetary scientists to Mars, to explore the question, \u2018Is there current life on Mars?’\u201d NASA\u2019s long-range plan calls for astronauts to start visiting Mars and its moons in the 2030s.<\/p>\n

\"pluto\"
\nScience journalist Alan Boyle<\/strong> is the author of “The Case for Pluto: How a Little Planet Made A Big Difference.”<\/p>\n

The streaks, known as recurring slope lineae, show up on imagery from NASA\u2019s Mars Reconnaissance Orbiter. During warm seasons on Mars, the dark streaks appear on steep slopes \u2013 extending up to 16 feet (5 meters) in width, and tens or hundreds of feet in length. They eventually fade away but reappear the next year in places where temperatures rise to the toasty level of 10 below zero Fahrenheit (-23 degrees Celsius).<\/p>\n

Scientists have long suspected that the streaks were caused by flows or seeps of salty water flowing down the Martian surface, but until now, they lacked direct evidence.<\/p>\n

In the latest study, Georgia Tech researcher Lujendra Ojha and his colleagues analyzed single pixels of imagery gathered by the orbiter\u2019s Compact Reconnaissance Imaging Spectrometer for Mars, or CRISM. They didn\u2019t detect the actual water, but they did see the chemical signature of salts that are typically left behind by brine, including several different flavors of perchlorates.<\/p>\n

The researchers theorize that such salts would make it possible for water to exist in a liquid state, even if the temperature stays below the freezing point for pure H2O. \u201cThese results strongly support the hypothesis that seasonal warm slopes are forming liquid water on contemporary Mars,\u201d they write.<\/p>\n

https:\/\/www.youtube.com\/watch?v=ymNhZiPKuCU<\/p>\n

They suggest three possibilities for the source of the water: melting ice ( which they say is \u201chighly unlikely\u201d), seasonal discharges from underground aquifers, or the absorption of atmospheric water vapor (which could form a thin film of salty water on the surface through a process known as deliquescence). Ojha and his colleagues draw a parallel to Chile\u2019s Atacama Desert, where deliquescence supports communities of salt-loving microbes in one of the driest places on Earth.<\/p>\n

\u201cThe detection described here warrants further astrobiological characterizations and exploration of these unique regions of Mars,\u201d the researchers write.<\/p>\n

Such findings could turn recurring slope lineae into potential targets for future missions to Mars. Scientists already have developed instruments capable of detecting microbes like the ones found in the Atacama Desert. However, the challenge of putting a lander or rover on a steep slope would be daunting.<\/p>\n

\u201cIt would be trivial for an astronaut in a spacesuit to go up and investigate,\u201d Grunsfeld said. \u201cBut it\u2019s very hard for a rover, so we\u2019re a little ways off.\u201d<\/p>\n

Future missions \u2013 such as NASA\u2019s InSight lander, due for launch next year, and the European Space Agency\u2019s ExoMars 2018 rover \u2013 will be equipped with drills to sample the Martian subsurface. Although the latest findings are intriguing, Grunsfeld said recurring slope lineae might not be the best places to look for Martian life.<\/p>\n

\u201cIf I were a microbe on Mars, I would probably not live near one of these RSLs,\u201d Grunsfeld said. \u201cI would want to live probably further north or south, higher latitudes, under the surface, quite far under the surface, and where there\u2019s more of a freshwater glacier. We only suspect those places exist, and we have some scientific evidence that they do. And that\u2019s the subject of future exploration.\u201d<\/p>\n

<\/span> Such a brine is not suitable for life and is of no interest for biology.<\/span><\/p>\n

Chris McKay, an astrobiologist at NASA\u2019s Ames Research Center who wasn\u2019t involved in the research, agreed that the dark streaks aren\u2019t the best places to look for life.<\/p>\n

\u201cAll life on Earth needs liquid water to grow or reproduce,\u201d he explained in an email to GeekWire. \u201cLife can be dormant in the dry state. Brines of sodium chloride (normal salt) are OK for life, too. However, there are brines on Earth that are too salty for life. The most famous is Don Juan Pond in Antarctica. This is the saltiest liquid water on Earth and is composed of saturated calcium chloride. Nothing can live in this brine.\u201d<\/p>\n

McKay noted that the briny traces observed on Mars are saturated solutions of perchlorate. \u201cThis brine is even saltier than the calcium chloride brine in Don Juan Pond,\u201d he said. \u201cSuch a brine is not suitable for life and is of no interest for biology. The result is of interest geologically.\u201d<\/p>\n

In addition to Ojha, the authors of \u201cSpectral Evidence for Hydrated Salts in Recurring Slope Lineae on Mars\u201d include Mary Beth Wilhelm, Scott Murchie, Alfred McEwen, James Wray, Jennifer Hanley, Marion Masse and Matt Chojnacki.<\/em><\/p>\n","protected":false},"excerpt":{"rendered":"

These dark streaks, shown flowing downhill in a false-color image from NASA\u2019s Mars Reconnaissance Orbiter, are inferred to have been formed by contemporary flowing water. (Credit: NASA \/ JPL \/ Univ. of Arizona) For years, scientists have puzzled over dark streaks that appear and disappear on the surface of Mars \u2013 and now they\u2019re confident enough […]<\/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":[1874,367,190,21],"class_list":["post-19603","post","type-post","status-publish","format-standard","hentry","category-news","tag-astrobiology","tag-mars","tag-nasa","tag-space"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/19603"}],"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=19603"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/19603\/revisions"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=19603"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=19603"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=19603"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}