"Long before it's in the papers"
September 29, 2015

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Finding “appears to confirm” liquid water on Mars

Sept. 29, 2015
Courtesy of NASA Jet Propulsion Laboratory
and World Science staff

New find­ings from NASA’s Mars Re­con­nais­sance Or­biter sat­el­lite pro­vide the strongest ev­i­dence yet that liq­uid wa­ter flows part of the time on Mars, sci­en­tists with the mis­sion said.

Us­ing an in­stru­ment on the sat­el­lite called an im­ag­ing spec­trom­e­ter, re­search­ers de­tected sig­na­tures of min­er­als as­so­ci­at­ed with wa­ter on slopes where mys­te­ri­ous streaks are seen on the Red Plan­et. 

Dark nar­row streaks, called "re­cur­ring slope lin­eae," em­a­nate from the walls of Gar­ni Crat­er on Mars, in this view con­structed from ob­ser­va­tions by the High Res­o­lu­tion Im­ag­ing Sci­ence Ex­per­i­ment (HiRISE) cam­era on NA­SA's Mars Re­con­nais­sance Or­biter. The dark streaks here are up to few hun­dred yards, or me­ters, long. They are hy­poth­e­sized to be formed by flow of briny liq­uid wa­ter on Mars. The im­age was pro­duced by first cre­at­ing a 3-D com­put­er mod­el (a dig­it­al ter­rain map) of the ar­ea based on stereo in­for­ma­tion from two HiRISE ob­ser­va­tions, and then drap­ing an im­age over the land-shape mod­el. The ver­ti­cal di­men­sion is ex­ag­ger­at­e by a fac­tor of 1.5 com­pared to hor­i­zon­tal di­men­sions. (Cred­it: NA­SA/JPL-Caltech/Univ. of Ar­i­zo­na)


The dark­ish streaks seem to ebb and flow over time—dark­en­ing and ap­pear­ing to flow down steep slopes in warm sea­sons, then fad­ing in cool­er sea­sons. 

They ap­pear in sev­er­al places when tem­per­a­tures are above mi­nus 10 de­grees Fahr­en­heit (mi­nus 23 Cel­sius), and disap­pear at colder times, ac­cord­ing to the re­search­ers.

“Our quest on Mars has been to ‘fol­low the wa­ter,’ in our search for life in the uni­verse, and now we have con­vinc­ing sci­ence that val­i­dates what we’ve long sus­pect­ed,” said John Grunsfeld, as­tro­naut and as­so­ci­ate ad­min­is­tra­tor of NASA’s Sci­ence Mis­sion Di­rec­to­rate in Wash­ing­ton. 

“This is a sig­nif­i­cant de­vel­op­ment, as it ap­pears to con­firm that wa­ter—albeit briny—is flow­ing to­day on the sur­face of Mars.”

The streaks, called re­cur­ring slope lin­eae, of­ten have been viewed as pos­sible signs of liq­uid wa­ter. The re­search­ers pro­pose that the salts de­tected would low­er the freez­ing point of wa­ter, just as salt fa­cil­i­tates ice melt­ing on roads here on Earth. Sci­en­tists say it’s likely a shal­low un­der­ground flow, with some wa­ter reach­ing the sur­face.

“We found the hy­drat­ed [wa­ter-containing] salts only when the sea­son­al fea­tures were wid­est, which sug­gests that ei­ther the dark streaks them­selves or a pro­cess that forms them is the source of the hydra­t­ion,” said Lu­jen­dra Ojha of the Geor­gia In­sti­tute of Tech­nol­o­gy, lead au­thor of a re­port on the find­ings pub­lished Sept. 28 in the jour­nal Na­ture Geo­sci­ence.

“In ei­ther case, the de­tec­tion of hy­drat­ed salts on these slopes means that wa­ter plays a vi­tal role in the forma­t­ion of these streaks.”

The NASA sat­el­lite has been ex­am­in­ing Mars since 2006 with its six sci­ence in­stru­ments.

Its abil­ity “to ob­serve for mul­ti­ple Mars years with a pay­load able to see the fi­ne de­tail of these fea­tures has ena­bled find­ings such as these: first iden­ti­fy­ing the puz­zling sea­son­al streaks and now mak­ing a big step to­wards ex­plaining what they are,” said Rich Zurek, proj­ect sci­ent­ist for the or­biter at NASA’s Je­t Pro­pul­sion Lab­o­r­a­to­ry in Pas­a­de­na, Cal­if.

For Ojha, the new find­ings are more proof that the mys­te­ri­ous lines he first saw dark­en­ing Mar­tian slopes five years ago are, in­deed, pre­s­ent-day wa­ter. “When most peo­ple talk about wa­ter on Mars, they’re usu­ally talk­ing about an­cient wa­ter or fro­zen wa­ter,” he said. “Now we know the­re’s more to the sto­ry.”


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New findings from NASA’s Mars Reconnaissance Orbiter satellite provide the strongest evidence yet that liquid water sometimes flows on Mars, scientists with the mission said. Using an instrument on the satellite called an imaging spectrometer, researchers detected signatures of minerals associated with water on slopes where mysterious streaks are seen on the Red Planet. The darkish streaks seem to ebb and flow over time—darkening and appearing to flow down steep slopes in warm seasons, then fading in cooler seasons. They appear in several locations on Mars when temperatures are above minus 10 degrees Fahrenheit (minus 23 Celsius), and disappear at colder times, according to the researchers. “Our quest on Mars has been to ‘follow the water,’ in our search for life in the universe, and now we have convincing science that validates what we’ve long suspected,” said John Grunsfeld, astronaut and associate administrator of NASA’s Science Mission Directorate in Washington. “This is a significant development, as it appears to confirm that water—albeit briny—is flowing today on the surface of Mars.” The downhill flows, known as recurring slope lineae, often have been described as possibly related to liquid water. The researchers propose that the salts detected would lower the freezing point of water, just as salt facilitates ice melting on roads here on Earth. Scientists say it’s likely a shallow underground flow, with enough water reaching to the surface to explain the darkening. “We found the hydrated [water-containing] salts only when the seasonal features were widest, which suggests that either the dark streaks themselves or a process that forms them is the source of the hydration,” said Lujendra Ojha of the Georgia Institute of Technology, lead author of a report on the findings published Sept. 28 in the journal Nature Geoscience. “In either case, the detection of hydrated salts on these slopes means that water plays a vital role in the formation of these streaks.” The NASA satellite has been examining Mars since 2006 with its six science instruments. Its ability “to observe for multiple Mars years with a payload able to see the fine detail of these features has enabled findings such as these: first identifying the puzzling seasonal streaks and now making a big step towards explaining what they are,” said Rich Zurek, project scientist for the orbiter at NASA’s Jet Propulsion Laboratory in Pasadena, California. For Ojha, the new findings are more proof that the mysterious lines he first saw darkening Martian slopes five years ago are, indeed, present-day water. “When most people talk about water on Mars, they’re usually talking about ancient water or frozen water,” he said. “Now we know there’s more to the story.”