There is possibly water flowing during the warmest months on Mars, according to strong evidence from NASA's Mars Reconnaissance Orbiter, or MRO.
Scientist have been searching Mars for decades hoping to find signs of the precious liquid that's said to be vital for life.
Scientists announced on Thursday that they've observed dark, finger-like features appearing and extending down some Martian slopes during late spring through summer, which fade in the winter and return during next spring. These recurring features were located on several steep slopes in Mars' southern hemisphere, according to NASA.
"The best explanation for these observations so far is the flow of briny water," said Alfred McEwen of the University of Arizona, Tucson, in a statement.
McEwen is the principal investigator for the orbiter's High Resolution Imaging Science Experiment, or HiRISE, and the lead author of a report about the recurring flows published in Thursday's edition of the journal Science.
"NASA's Mars Exploration Program keeps bringing us closer to determining whether the Red Planet could harbor life in some form," NASA Administrator Charles Bolden said in a statement, "and it reaffirms Mars as an important future destination for human exploration." NASA said there are some aspects of the observations that still puzzle researchers, but flows of liquid brine fit the features' characteristics better than alternate hypotheses.
Saltiness lowers the freezing temperature of water, according to NASA.
"These dark lineations are different from other types of features on Martian slopes," said MRO project scientist Richard Zurek of NASA's Jet Propulsion Laboratory in Pasadena, Calif., in a statement. "Repeated observations show they extend ever farther downhill with time during the warm season."
The brine streaks are about 0.5 to 5 yards or meters wide, with lengths up to hundreds of yards down these slopes. Additionally, the width is much narrower than previously reported gullies on Martian slopes, according to NASA.
Some of those locations display more than 1,000 individual flows. Also, while gullies are abundant on cold, pole-facing slopes, these dark flows are on warmer, equator-facing slopes, the space agency said.
The images of the findings show flows lengthen and darken on rocky equator-facing slopes from late spring to early fall, and the seasonality, latitude distribution and brightness changes suggest a volatile material is involved, but there is no direct detection of one, NASA said.
The agency also said the settings are too warm for carbon-dioxide frost and, at some sites, too cold for pure water, which suggests that it's possibly brines, which have lower freezing points.
These salt deposits over much of Mars show that brines were plentiful in Mars' past, and these recent observations suggest brines still may form near the surface today in limited times and places, NASA said, adding that these features may quickly dry on the surface or could be shallow subsurface flows.
"The flows are not dark because of being wet," McEwen said in a statement. "They are dark for some other reason."
NASA said a flow originated by briny water could reorganize grains or change surface roughness that could darken the appearance. But the scientists found it hard to explain how the features brighten again when temperatures drop.
"It's a mystery now, but I think it's a solvable mystery with further observations and laboratory experiments," McEwen said.
This series of images shows warm-season features that might be evidence of salty liquid water active on Mars today. Evidence for that possible interpretation is presented in a report by McEwen et al. in the Aug. 5, 2011, edition of Science.These images come from observations of Newton crater, at 41.6 degrees south latitude, 202.3 degrees east longitude, by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter. In time, the series spans from early spring of one Mars year to mid-summer of the following year. The images have been adjusted to correct those taken from oblique angles to show how the scene would look from directly overhead.The features that extend down the slope during warm seasons are called recurring slope lineae. They are narrow (one-half to five yards or meters wide), relatively dark markings on steep (25 to 40 degree) slopes at several southern hemisphere locations. Repeat imaging by HiRISE shows the features appear and incrementally grow during warm seasons and fade in cold seasons. They extend downslope from bedrock outcrops, often associated with small channels, and hundreds of them form in rare locations. They appear and lengthen in the southern spring and summer from 48 degrees to 32 degrees south latitudes favoring equator-facing slopes. These times and places have peak surface temperatures from about 10 degrees below zero Fahrenheit to 80 degree above zero Fahrenheit (about 250 to 300 Kelvin). Liquid brines near the surface might explain this activity, but the exact mechanism and source of the water are not understood.The series is timed to dwell two seconds on the first and last frames and one second on intermediate frames, though network or computer performance may cause this to vary.NASA/JPL-Caltech/Univ. of ArizThis series of images shows warm-season features that might be evidence of salty liquid water active on Mars today. Evidence for that possible interpretation is presented in a report by McEwen et al. in the Aug. 5, 2011, edition of Science.These images come from observations of Newton crater, at 41.6 degrees south latitude, 202.3 degrees east longitude, by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter. In time, the series spans from late spring to early summer of a Mars year. The images taken from oblique angles have been adjusted so that all steps in the sequence show the scene as if viewed from directly overhead.The features that extend down the slope during warm seasons are called recurring slope lineae. They are narrow (one-half to five yards or meters wide), relatively dark markings on steep (25 to 40 degree) slopes at several southern hemisphere locations. Repeat imaging by HiRISE shows the features appear and incrementally grow during warm seasons and fade in cold seasons. They extend downslope from bedrock outcrops, often associated with small channels, and hundreds of them form in rare locations. They appear and lengthen in the southern spring and summer from 48 degrees to 32 degrees south latitudes favoring equator-facing slopes. These times and places have peak surface temperatures from about 10 degrees below zero Fahrenheit to 80 degree above zero Fahrenheit (about 250 to 300 Kelvin). Liquid brines near the surface might explain this activity, but the exact mechanism and source of the water are not understood. The series is timed to dwell two seconds on the first and last frames and one second on intermediate frames, though network or computer performance may cause this to vary.NASA/JPL-Caltech/Univ. of ArizThis map of Mars shows relative locations of three types of findings related to salt or frozen water, plus a new type of finding that may be related to both salt and water.Coloring of the map is coded to concentrations of shallow subsurface water ice found by the Gamma Ray Spectrometer - Neutron Spectrometer on NASA's Mars Odyssey orbiter. Blue, at high latitudes north and south, indicates higher concentrations of water ice (deduced from detection of hydrogen); orange designates lowest concentrations. Some hydrogen, possibly in the form of bound water, is close to the surface even at middle latitudes.The white squares in the northern hemisphere mark locations of small fresh impact craters that exposed water ice close to the surface and validated the neutron spectrometer data. Observations of these fresh craters were made by the Context Camera and the High Resolution Imaging Science Experiment camera on NASA's Mars Reconnaissance Orbiter.The red squares mark locations of putative deposits of chlorite based on observations by the Thermal Emission Imaging System on Mars Odyssey. Such salt deposits could have resulted from evaporation of salty water.The blue squares mark locations of a type of feature reported in August 2011 based on sequences of observations by the High Resolution Imaging Science Experiment. The observations show relatively dark features appearing and incrementally growing down slopes during warm seasons. Researchers hypothesize that these features may result from action of briny water.NASA/JPL-Caltech/ASU/UA/LANL/MThis series of images shows warm-season features that might be evidence of salty liquid water active on Mars today. Evidence for that possible interpretation is presented in a report by McEwen et al. in the Aug. 5, 2011, edition of Science.These images come from observations of Newton crater, at 41.6 degrees south latitude, 202.3 degrees east longitude, by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter. In time, the series spans from early spring of one Mars year to mid-summer of the following year. The images taken from oblique angles have been adjusted so that all steps in the sequence show the scene as if viewed from directly overhead.The features that extend down the slope during warm seasons are called recurring slope lineae. They are narrow (one-half to five yards or meters wide), relatively dark markings on steep (25 to 40 degree) slopes at several southern hemisphere locations. Repeat imaging by HiRISE shows the features appear and incrementally grow during warm seasons and fade in cold seasons. They extend downslope from bedrock outcrops, often associated with small channels, and hundreds of them form in rare locations. They appear and lengthen in the southern spring and summer from 48 degrees to 32 degrees south latitudes favoring equator-facing slopes. These times and places have peak surface temperatures from about 10 degrees below zero Fahrenheit to 80 degree above zero Fahrenheit (about 250 to 300 Kelvin). Liquid brines near the surface might explain this activity, but the exact mechanism and source of the water are not understood.NASA/JPL-Caltech/Univ. of ArizThis series of images shows warm-season features that might be evidence of salty liquid water active on Mars today. Evidence for that possible interpretation is presented in a report by McEwen et al. in the Aug. 5, 2011, edition of Science.These images come from observations of Horowitz crater, at 32 degrees south latitude, 141 degrees east longitude, by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter. In time, the series spans from late summer of one Mars year to mid-summer of two years later. The images taken from oblique angles have been adjusted so that all steps in the sequence show the scene as if viewed from directly overhead.The features that extend down the slope during warm seasons are called recurring slope lineae. They are narrow (one-half to five yards or meters wide), relatively dark markings on steep (25 to 40 degree) slopes at several southern hemisphere locations. Repeat imaging by HiRISE shows the features appear and incrementally grow during warm seasons and fade in cold seasons. They extend downslope from bedrock outcrops, often associated with small channels, and hundreds of them form in rare locations. They appear and lengthen in the southern spring and summer from 48 degrees to 32 degrees south latitudes favoring equator-facing slopes. These times and places have peak surface temperatures from about 10 degrees below zero Fahrenheit to 80 degree above zero Fahrenheit (about 250 to 300 Kelvin). Liquid brines near the surface might explain this activity, but the exact mechanism and source of the water are not understood.NASA/JPL-Caltech/Univ. of ArizThis series of images shows warm-season features that might be evidence of salty liquid water active on Mars today. Evidence for that possible interpretation is presented in a report by McEwen et al. in the Aug. 5, 2011, edition of Science.These images come from observations of a steep crater slope in the Terra Cimmeria region of Mars, at 38.8 degrees south latitude, 159.5 degrees east longitude, by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter. In time, the series spans from the end of summer of one Mars year to mid-summer of two years later. The images taken from oblique angles have been adjusted so that all steps in the sequence show the scene as if viewed from directly overhead.The features that extend down the slope during warm seasons are called recurring slope lineae. They are narrow (one-half to five yards or meters wide), relatively dark markings on steep (25 to 40 degree) slopes at several southern hemisphere locations. Repeat imaging by HiRISE shows the features appear and incrementally grow during warm seasons and fade in cold seasons. They extend downslope from bedrock outcrops, often associated with small channels, and hundreds of them form in rare locations. They appear and lengthen in the southern spring and summer from 48 degrees to 32 degrees south latitudes favoring equator-facing slopes. These times and places have peak surface temperatures from about 10 degrees below zero Fahrenheit to 80 degree above zero Fahrenheit (about 250 to 300 Kelvin). Liquid brines near the surface might explain this activity, but the exact mechanism and source of the water are not understood.NASA/JPL-Caltech/Univ. of ArizAn image combining orbital imagery with 3-D modeling shows flows that appear in spring and summer on a slope inside Mars' Newton crater. Sequences of observations recording the seasonal changes at this site and a few others with similar flows might be evidence of salty liquid water active on Mars today. Evidence for that possible interpretation is presented in a report by McEwen et al. in the Aug. 5, 2011, edition of Science.This image has been reprojected to show a view of a slope as it would be seen from a helicopter inside the crater, with a synthetic Mars-like sky. The source observation was made May 30, 2011, by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter. Color has been enhanced. The season was summer at the location, 41.6 degrees south latitude, 202.3 degrees east longitude.The flow features are narrow (one-half to five yards or meters wide), relatively dark markings on steep (25 to 40 degree) slopes at several southern hemisphere locations. Repeat imaging by HiRISE shows the features appear and incrementally grow during warm seasons and fade in cold seasons.HiRISE is operated by the University of Arizona, Tucson, and the instrument was built by Ball Aerospace & Technologies Corp., Boulder, Colo. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, built the spacecraft.NASA/JPL-Caltech/Univ. of Ariz
