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News Article | May 5, 2017
Site: phys.org

From early February to early April, the rover examined four sites near a linear dune for comparison with what it found in late 2015 and early 2016 during its investigation of crescent-shaped dunes. This two-phase campaign is the first close-up study of active dunes anywhere other than Earth. Among the questions this Martian dune campaign is addressing is how winds shape dunes that are relatively close together, on the same side of the same mountain, into different patterns. Others include whether Martian winds sort grains of sand in ways that affect the distribution of mineral compositions, which would have implications for studies of Martian sandstones. "At these linear dunes, the wind regime is more complicated than at the crescent dunes we studied earlier," said Mathieu Lapotre of Caltech, in Pasadena, California, who helped lead the Curiosity science team's planning for the dune campaign. "There seems to be more contribution from the wind coming down the slope of the mountain here compared with the crescent dunes farther north." The linear dunes lie uphill and about a mile (about 1.6 kilometers) south from the crescent dunes. Both study locations are part of a dark-sand swath called the Bagnold Dunes, which stretches several miles in length. This dune field lines the northwestern flank of Mount Sharp, the layered mountain that Curiosity is climbing. "There was another key difference between the first and second phases of our dune campaign, besides the shape of the dunes," Lapotre said. "We were at the crescent dunes during the low-wind season of the Martian year and at the linear dunes during the high-wind season. We got to see a lot more movement of grains and ripples at the linear dunes." To assess wind strength and direction, the rover team now uses change-detection pairs of images taken at different times to check for movement of sand grains. The wind-sensing capability of the Curiosity's Rover Environmental Monitoring Station (REMS) is no longer available, though that instrument still returns other Mars-weather data daily, such as temperatures, humidity and pressure. Two of the six wind sensors on the rover's mast were found to be inoperable upon landing on Mars in 2012. The remainder provided wind information throughout the rover's prime mission and first two-year extended mission. A sample of sand that Curiosity scooped up from a linear dune is in the sample-handling device at the end of the rover's arm. One portion has been analyzed in the Sample Analysis at Mars (SAM) instrument inside the rover. The science team plans to deliver additional sample portions to SAM and to the rover's Chemistry and Mineralogy (CheMin) instrument. One factor in choosing to drive farther uphill before finishing analysis of the scooped sand is the status of Curiosity's rock-sampling drill, which has not been used on a rock since a problem with the drill feed mechanism appeared five months ago. Engineers are assessing how the use of vibration to deliver samples may affect the drill feed mechanism, which is used to move the drill bit forward and backwards. In addition, high winds at the linear-dunes location were complicating the process of pouring sample material into the entry ports for the laboratory instruments. "A balky brake appears to be affecting drill feed mechanism performance," said Curiosity Deputy Project Manager Steven Lee, of NASA's Jet Propulsion Laboratory, Pasadena, California. "In some cases, vibration has been observed to change feed effectiveness, so we're proceeding cautiously until we better understand the behavior. In the meantime, the engineering team is developing several methods to improve feed reliability." Curiosity landed near Mount Sharp in August 2012. It reached the base of the mountain in 2014 after successfully finding evidence on the surrounding plains that ancient Martian lakes offered conditions that would have been favorable for microbes if Mars has ever hosted life. Rock layers forming the base of Mount Sharp accumulated as sediment within ancient lakes billions of years ago. On Mount Sharp, Curiosity is investigating how and when the ancient habitable conditions known from the mission's earlier findings evolved into drier conditions that were less favorable for life. More information: For more information about Curiosity, visit mars.jpl.nasa.gov/msl


News Article | August 5, 2017
Site: www.techtimes.com

Five years ago, the Curiosity Rover landed on Mars to explore the red planet. Here are some things you may want to know about the explorer and its mission. It was at 10:32 p.m. PDT on Aug. 5, 2012 (1:32 a.m. EDP, Aug. 6, 2012) that Curiosity landed on Mars. Since then, it has rolled on along the surface of Mars to complete its mission. Sadly, the rover had always been celebrating its birthday alone and still on the job as it apparently sings itself a "Happy Birthday" song each year. Aptly named Curiosity, Mars Science Laboratory's (MSL) rover is a part of NASA's Mars Exploration Program. Simply put, Curiosity's mission is to assess whether the planet ever had the capability to support life forms in the form of microbes. Amazingly, Curiosity was able to complete its mission less than a year after its arrival when it determined that an ancient lake in Mars likely had the conditions needed to support life such as fresh water. With the help of an Autonomous Exploration for Gathering Increased Science (AEGIS), Curiosity has the capability to choose which rocks to test even without the help of humans. AEGIS first identifies interesting-looking rocks and allows Curiosity to use ChemCam to blast the rocks with the laser and analyze the resulting gases. Because of this capability, no time is lost during Curiosity's mission as it can continue to explore while waiting for orders from controllers. Curiosity's six wheels are made of solid aluminum with titanium spokes on the inside. Still, they were not spared by Mars' harsh terrain. In 2013, Curiosity experienced substantial damage to its wheels as it was rolling along a terrain littered with sharp rocks. Earlier in 2017, two of the grousers on the Curiosity's left middle wheel broke. Despite this, Curiosity rolls on as NASA states that the broken wheels do not affect its mission significantly. Curiosity rover is loaded — with science instruments, that is. After looking at the proposals submitted to NASA in April 2004, the team selected science instruments best suited to Curiosity's mission. These instruments include the Sample Analysis at Mars which has a gas chromatograph, a mass spectrometer, a tunable laser spectrometer, an X-Ray diffraction instrument called CheMin, the ChemCam, the Dynamic Albedo of Neutrons which is used to detect hydrogen in minerals, and the Mars Hand Lens Imager which takes extreme close-ups of rocks and soil. Other instruments include the Alpha Particle X-Ray Spectrometer, the Mast Camera, the Mars Descent Imager which captured a colored, high-definition video of the rover's landing, and the Rover Environmental Monitoring Station. Here is a glimpse of what Curiosity has been doing on Mars for the last five years. © 2017 Tech Times, All rights reserved. Do not reproduce without permission.


News Article | June 13, 2017
Site: www.techtimes.com

Researchers reveal that Mars may have hosted diverse environments in its ancient past. The scientists examined the rocks samples NASA's Curiosity rover gathered on Mars to arrive at this conclusion. As part of the study, the researchers discovered a wide diversity in the minerals that were deposited in layers on the sedimentary rocks collected from the base of Mars' Mount Sharp. The NASA Curiosity rover landed on the Red Planet's 96-mile-wide Gale Crater in 2012 and took another two years to reach Mount Sharp, which is located at the crater's center. Shortly upon its landing, the Curiosity rover found evidence that the Gale Crater was once home to a diverse environment and could have been a "lake-and-stream system" in Mars's ancient past. "We went to Gale Crater to investigate these lower layers of Mount Sharp that have these minerals that precipitated from water and suggest different environments," the study's first author Elizabeth Rampe remarked. Rampe also shared that these mineral layers were deposited roughly 3.5 billion years ago, at a time when the Earth was taking its first steps toward supporting life. The researchers posit that ancient Mars was possibly similar to the Earth in its initial days. The Red Planet's early environment was possibly even habitable. The researchers note that the collection of minerals found in the four samples from Mars' Mount Sharp reveal that they precipitated into layers because of water presence. The diversity in the minerals layer deposits also reveal that the Gale Crater was home to not one, but multiple environments. The sedimentary rock samples that contained the mineral deposits were drilled out from the base of Mount Sharp. The range of mineral deposits that were found in layers also hint at the presence of water around the rock base. This water had different pH levels and unpredictable oxidizing conditions. The rock samples also suggested that there could be more than one source region for the Marias Pass and Pahrump Hills regions' sedimentary rocks. All the four rock samples examined revealed a wide diversity of minerals. Three of the rock samples were collected from the Pahrump Hills region, whereas the fourth was found in 2016 and named "Buckskin." These rocks were then studied using the Chemistry and Mineralogy or CheMin instrument aboard the Curiosity rover. The researchers found that the base mineral's source was prehistoric magma, rich in magnesium and iron similar to the basalt rocks found in Hawaii. The scientists observed that more layers situated higher were composed of silica-rich minerals. © 2017 Tech Times, All rights reserved. Do not reproduce without permission.


News Article | June 9, 2017
Site: www.chromatographytechniques.com

NASA scientists have found a wide diversity of minerals in the initial samples of rocks collected by the Curiosity rover in the lowermost layers of Mount Sharp on Mars, suggesting that conditions changed in the water environments on the planet over time. Curiosity landed near Mount Sharp in Gale Crater in August 2012. It reached the base of the mountain in 2014. Layers of rocks at the base of Mount Sharp accumulated as sediment within ancient lakes around 3.5 billion years ago. Orbital infrared spectroscopy had shown that the mountain's lowermost layers have variations in minerals that suggest changes in the area have occurred. In a paper published recently in Earth and Planetary Science Letters, scientists in the Astromaterials Research and Exploration Science (ARES) Division at NASA's Johnson Space Center in Houston report on the first four samples collected from the lower layers of Mount Sharp. "We went to Gale Crater to investigate these lower layers of Mount Sharp that have these minerals that precipitated from water and suggest different environments," said Elizabeth Rampe, the first author of the study and a NASA exploration mission scientist at Johnson. "These layers were deposited about 3.5 billion years ago, coinciding with a time on Earth when life was beginning to take hold. We think early Mars may have been similar to early Earth, and so these environments might have been habitable." The minerals found in the four samples drilled near the base of Mount Sharp suggest several different environments were present in ancient Gale Crater. There is evidence for waters with different pH and variably oxidizing conditions. The minerals also show that there were multiple source regions for the rocks in "Pahrump Hills" and "Marias Pass." The paper primarily reports on three samples from the Pahrump Hills region. This is an outcrop at the base of Mount Sharp that contains sedimentary rocks scientists believe formed in the presence of water. The other sample, called "Buckskin," was reported last year, but those data are incorporated into the paper. Studying such rock layers can yield information about Mars' past habitability, and determining minerals found in the layers of sedimentary rock yields much data about the environment in which they formed. Data collected at Mount Sharp with the Chemistry and Mineralogy (CheMin) instrument on Curiosity showed a wide diversity of minerals. At the base are minerals from a primitive magma source; they are rich in iron and magnesium, similar to basalts in Hawaii. Moving higher in the section, scientists saw more silica-rich minerals. In the "Telegraph Peak" sample, scientists found minerals similar to quartz. In the "Buckskin" sample, scientists found tridymite. Tridymite is found on Earth, for example, in rocks that formed from partial melting of Earth's crust or in the continental crust -- a strange finding because Mars never had plate tectonics. In the "Confidence Hills" and "Mojave 2" samples, scientists found clay minerals, which generally form in the presence of liquid water with a near-neutral pH, and therefore could be good indicators of past environments that were conducive to life. The other mineral discovered here was jarosite, a salt that forms in acidic solutions. The jarosite finding indicates that there were acidic fluids at some point in time in this region. There are different iron-oxide minerals in the samples as well. Hematite was found near the base; only magnetite was found at the top. Hematite contains oxidized iron, whereas magnetite contains both oxidized and reduced forms of iron. The type of iron-oxide mineral present may tell scientists about the oxidation potential of the ancient waters. The authors discuss two hypotheses to explain this mineralogical diversity. The lake waters themselves at the base were oxidizing, so either there was more oxygen in the atmosphere or other factors encouraged oxidation. Another hypothesis -- the one put forward in the paper -- is that later-stage fluids arose. After the rock sediments were deposited, some acidic, oxidizing groundwater moved into the area, leading to precipitation of the jarosite and hematite. In this scenario, the environmental conditions present in the lake and in later groundwater were quite different, but both offered liquid water and a chemical diversity that could have been exploited by microbial life. "We have all this evidence that Mars was once really wet but now is dry and cold," Rampe said. "Today, much of the water is locked up in the poles and in the ground at high latitudes as ice. We think that the rocks Curiosity has studied reveal ancient environmental changes that occurred as Mars started to lose its atmosphere and water was lost to space." In the paper, the authors discuss whether this specific area on Mars is a mark of this event happening or just a natural drying of this area. Scientists will search for answers to these questions as the rover moves up the mountain.


News Article | June 12, 2017
Site: www.chromatographytechniques.com

NASA scientists have found a wide diversity of minerals in the initial samples of rocks collected by the Curiosity rover in the lowermost layers of Mount Sharp on Mars, suggesting that conditions changed in the water environments on the planet over time. Curiosity landed near Mount Sharp in Gale Crater in August 2012. It reached the base of the mountain in 2014. Layers of rocks at the base of Mount Sharp accumulated as sediment within ancient lakes around 3.5 billion years ago. Orbital infrared spectroscopy had shown that the mountain's lowermost layers have variations in minerals that suggest changes in the area have occurred. In a paper published recently in Earth and Planetary Science Letters, scientists in the Astromaterials Research and Exploration Science (ARES) Division at NASA's Johnson Space Center in Houston report on the first four samples collected from the lower layers of Mount Sharp. "We went to Gale Crater to investigate these lower layers of Mount Sharp that have these minerals that precipitated from water and suggest different environments," said Elizabeth Rampe, the first author of the study and a NASA exploration mission scientist at Johnson. "These layers were deposited about 3.5 billion years ago, coinciding with a time on Earth when life was beginning to take hold. We think early Mars may have been similar to early Earth, and so these environments might have been habitable." The minerals found in the four samples drilled near the base of Mount Sharp suggest several different environments were present in ancient Gale Crater. There is evidence for waters with different pH and variably oxidizing conditions. The minerals also show that there were multiple source regions for the rocks in "Pahrump Hills" and "Marias Pass. The paper primarily reports on three samples from the Pahrump Hills region. This is an outcrop at the base of Mount Sharp that contains sedimentary rocks scientists believe formed in the presence of water. The other sample, called "Buckskin," was reported last year, but those data are incorporated into the paper. Studying such rock layers can yield information about Mars' past habitability, and determining minerals found in the layers of sedimentary rock yields much data about the environment in which they formed. Data collected at Mount Sharp with the Chemistry and Mineralogy (CheMin) instrument on Curiosity showed a wide diversity of minerals. At the base are minerals from a primitive magma source; they are rich in iron and magnesium, similar to basalts in Hawaii. Moving higher in the section, scientists saw more silica-rich minerals. In the "Telegraph Peak" sample, scientists found minerals similar to quartz. In the "Buckskin" sample, scientists found tridymite. Tridymite is found on Earth, for example, in rocks that formed from partial melting of Earth's crust or in the continental crust -- a strange finding because Mars never had plate tectonics. In the "Confidence Hills" and "Mojave 2" samples, scientists found clay minerals, which generally form in the presence of liquid water with a near-neutral pH, and therefore could be good indicators of past environments that were conducive to life. The other mineral discovered here was jarosite, a salt that forms in acidic solutions. The jarosite finding indicates that there were acidic fluids at some point in time in this region. There are different iron-oxide minerals in the samples as well. Hematite was found near the base; only magnetite was found at the top. Hematite contains oxidized iron, whereas magnetite contains both oxidized and reduced forms of iron. The type of iron-oxide mineral present may tell scientists about the oxidation potential of the ancient waters. The authors discuss two hypotheses to explain this mineralogical diversity. The lake waters themselves at the base were oxidizing, so either there was more oxygen in the atmosphere or other factors encouraged oxidation. Another hypothesis -- the one put forward in the paper -- is that later-stage fluids arose. After the rock sediments were deposited, some acidic, oxidizing groundwater moved into the area, leading to precipitation of the jarosite and hematite. In this scenario, the environmental conditions present in the lake and in later groundwater were quite different, but both offered liquid water and a chemical diversity that could have been exploited by microbial life. "We have all this evidence that Mars was once really wet but now is dry and cold," Rampe said. "Today, much of the water is locked up in the poles and in the ground at high latitudes as ice. We think that the rocks Curiosity has studied reveal ancient environmental changes that occurred as Mars started to lose its atmosphere and water was lost to space." In the paper, the authors discuss whether this specific area on Mars is a mark of this event happening or just a natural drying of this area. Scientists will search for answers to these questions as the rover moves up the mountain.


News Article | June 12, 2017
Site: phys.org

Curiosity landed near Mount Sharp in Gale Crater in August 2012. It reached the base of the mountain in 2014. Layers of rocks at the base of Mount Sharp accumulated as sediment within ancient lakes around 3.5 billion years ago. Orbital infrared spectroscopy had shown that the mountain's lowermost layers have variations in minerals that suggest changes in the area have occurred. In a paper published recently in Earth and Planetary Science Letters, scientists in the Astromaterials Research and Exploration Science (ARES) Division at NASA's Johnson Space Center in Houston report on the first four samples collected from the lower layers of Mount Sharp. "We went to Gale Crater to investigate these lower layers of Mount Sharp that have these minerals that precipitated from water and suggest different environments," said Elizabeth Rampe, the first author of the study and a NASA exploration mission scientist at Johnson. "These layers were deposited about 3.5 billion years ago, coinciding with a time on Earth when life was beginning to take hold. We think early Mars may have been similar to early Earth, and so these environments might have been habitable." The minerals found in the four samples drilled near the base of Mount Sharp suggest several different environments were present in ancient Gale Crater. There is evidence for waters with different pH and variably oxidizing conditions. The minerals also show that there were multiple source regions for the rocks in "Pahrump Hills" and "Marias Pass." The paper primarily reports on three samples from the Pahrump Hills region. This is an outcrop at the base of Mount Sharp that contains sedimentary rocks scientists believe formed in the presence of water. The other sample, called "Buckskin," was reported last year, but those data are incorporated into the paper. Studying such rock layers can yield information about Mars' past habitability, and determining minerals found in the layers of sedimentary rock yields much data about the environment in which they formed. Data collected at Mount Sharp with the Chemistry and Mineralogy (CheMin) instrument on Curiosity showed a wide diversity of minerals. At the base are minerals from a primitive magma source; they are rich in iron and magnesium, similar to basalts in Hawaii. Moving higher in the section, scientists saw more silica-rich minerals. In the "Telegraph Peak" sample, scientists found minerals similar to quartz. In the "Buckskin" sample, scientists found tridymite. Tridymite is found on Earth, for example, in rocks that formed from partial melting of Earth's crust or in the continental crust—a strange finding because Mars never had plate tectonics. In the "Confidence Hills" and "Mojave 2" samples, scientists found clay minerals, which generally form in the presence of liquid water with a near-neutral pH, and therefore could be good indicators of past environments that were conducive to life. The other mineral discovered here was jarosite, a salt that forms in acidic solutions. The jarosite finding indicates that there were acidic fluids at some point in time in this region. There are different iron-oxide minerals in the samples as well. Hematite was found near the base; only magnetite was found at the top. Hematite contains oxidized iron, whereas magnetite contains both oxidized and reduced forms of iron. The type of iron-oxide mineral present may tell scientists about the oxidation potential of the ancient waters. The authors discuss two hypotheses to explain this mineralogical diversity. The lake waters themselves at the base were oxidizing, so either there was more oxygen in the atmosphere or other factors encouraged oxidation. Another hypothesis—the one put forward in the paper—is that later-stage fluids arose. After the rock sediments were deposited, some acidic, oxidizing groundwater moved into the area, leading to precipitation of the jarosite and hematite. In this scenario, the environmental conditions present in the lake and in later groundwater were quite different, but both offered liquid water and a chemical diversity that could have been exploited by microbial life. "We have all this evidence that Mars was once really wet but now is dry and cold," Rampe said. "Today, much of the water is locked up in the poles and in the ground at high latitudes as ice. We think that the rocks Curiosity has studied reveal ancient environmental changes that occurred as Mars started to lose its atmosphere and water was lost to space." In the paper, the authors discuss whether this specific area on Mars is a mark of this event happening or just a natural drying of this area. Scientists will search for answers to these questions as the rover moves up the mountain. Explore further: Rover findings indicate stratified lake on ancient Mars More information: E.B. Rampe et al. Mineralogy of an ancient lacustrine mudstone succession from the Murray formation, Gale crater, Mars, Earth and Planetary Science Letters (2017). DOI: 10.1016/j.epsl.2017.04.021


News Article | December 13, 2016
Site: astrobiology.com

NASA's Curiosity rover is climbing a layered Martian mountain and finding evidence of how ancient lakes and wet underground environments changed, billions of years ago, creating more diverse chemical environments that affected their favorability for microbial life. Hematite, clay minerals and boron are among the ingredients found to be more abundant in layers farther uphill, compared with lower, older layers examined earlier in the mission. Scientists are discussing what these and other variations tell about conditions under which sediments were initially deposited, and about how groundwater moving later through the accumulated layers altered and transported ingredients. Effects of this groundwater movement are most evident in mineral veins. The veins formed where cracks in the layers were filled with chemicals that had been dissolved in groundwater. The water with its dissolved contents also interacted with the rock matrix surrounding the veins, altering the chemistry both in the rock and in the water. "There is so much variability in the composition at different elevations, we've hit a jackpot," said John Grotzinger, of Caltech in Pasadena, California. He and other members of Curiosity's science team presented an update about the mission Tuesday, Dec. 13, in San Francisco during the fall meeting of the American Geophysical Union. As the rover examines higher, younger layers, researchers are impressed by the complexity of the lake environments when clay-bearing sediments were being deposited, and also the complexity of the groundwater interactions after the sediments were buried. "A sedimentary basin such as this is a chemical reactor," Grotzinger said. "Elements get rearranged. New minerals form and old ones dissolve. Electrons get redistributed. On Earth, these reactions support life." Whether Martian life has ever existed is still unknown. No compelling evidence for it has been found. When Curiosity landed in Mars' Gale Crater in 2012, the mission's main goal was to determine whether the area ever offered an environment favorable for microbes. The crater's main appeal for scientists is geological layering exposed in the lower portion of its central mound, Mount Sharp. These exposures offer access to rocks that hold a record of environmental conditions from many stages of early Martian history, each layer younger than the one beneath it. The mission succeeded in its first year, finding that an ancient Martian lake environment had all the key chemical ingredients needed for life, plus chemical energy available for life. Now, the rover is climbing lower on Mount Sharp to investigate how ancient environmental conditions changed over time. "We are well into the layers that were the main reason Gale Crater was chosen as the landing site," said Curiosity Deputy Project Scientist Joy Crisp of NASA's Jet Propulsion Laboratory, in Pasadena, California. "We are now using a strategy of drilling samples at regular intervals as the rover climbs Mount Sharp. Earlier we chose drilling targets based on each site's special characteristics. Now that we're driving continuously through the thick basal layer of the mountain, a series of drill holes will build a complete picture." Four recent drilling sites, from "Oudam" this past June through "Sebina" in October, are each spaced about 80 feet (about 25 meters) apart in elevation. This uphill pattern allows the science team to sample progressively younger layers that reveal Mount Sharp's ancient environmental history. One clue to changing ancient conditions is the mineral hematite. It has replaced less-oxidized magnetite as the dominant iron oxide in rocks Curiosity has drilled recently, compared with the site where Curiosity first found lakebed sediments. "Both samples are mudstone deposited at the bottom of a lake, but the hematite may suggest warmer conditions, or more interaction between the atmosphere and the sediments," said Thomas Bristow of NASA Ames Research Center, Moffett Field, California. He helps operate the Chemistry and Mineralogy (CheMin) laboratory instrument inside the rover, which identifies minerals in collected samples. Chemical reactivity occurs on a gradient of chemical ingredients' strength at donating or receiving electrons. Transfer of electrons due to this gradient can provide energy for life. An increase in hematite relative to magnetite indicates an environmental change in the direction of tugging electrons more strongly, causing a greater degree of oxidation in iron. Another ingredient increasing in recent measurements by Curiosity is the element boron, which the rover's laser-shooting Chemistry and Camera (ChemCam) instrument has been detecting within mineral veins that are mainly calcium sulfate. "No prior mission has detected boron on Mars," said Patrick Gasda of the U.S. Department of Energy's Los Alamos National Laboratory, Los Alamos, New Mexico. "We're seeing a sharp increase in boron in vein targets inspected in the past several months." The instrument is quite sensitive; even at the increased level, boron makes up only about one-tenth of one percent of the rock composition. Boron is famously associated with arid sites where much water has evaporated away -- think of the borax that mule teams once hauled from Death Valley. However, environmental implications of the minor amount of boron found by Curiosity are less straightforward than for the increase in hematite. Scientists are considering at least two possibilities for the source of boron that groundwater left in the veins. Perhaps evaporation of a lake formed a boron-containing deposit in an overlying layer, not yet reached by Curiosity, then water later re-dissolved the boron and carried it down through a fracture network into older layers, where it accumulated along with fracture-filling vein minerals. Or perhaps changes in the chemistry of clay-bearing deposits, such as evidenced by the increased hematite, affected how groundwater picked up and dropped off boron within the local sediments. "Variations in these minerals and elements indicate a dynamic system," Grotzinger said. "They interact with groundwater as well as surface water. The water influences the chemistry of the clays, but the composition of the water also changes. We are seeing chemical complexity indicating a long, interactive history with the water. The more complicated the chemistry is, the better it is for habitability. The boron, hematite and clay minerals underline the mobility of elements and electrons, and that is good for life." Curiosity is part of NASA's ongoing Mars research and preparation for a human mission to Mars in the 2030s. Caltech manages JPL, and JPL manages the Curiosity mission for NASA's Science Mission Directorate in Washington.


News Article | December 13, 2016
Site: phys.org

Hematite, clay minerals and boron are among the ingredients found to be more abundant in layers farther uphill, compared with lower, older layers examined earlier in the mission. Scientists are discussing what these and other variations tell about conditions under which sediments were initially deposited, and about how groundwater moving later through the accumulated layers altered and transported ingredients. Effects of this groundwater movement are most evident in mineral veins. The veins formed where cracks in the layers were filled with chemicals that had been dissolved in groundwater. The water with its dissolved contents also interacted with the rock matrix surrounding the veins, altering the chemistry both in the rock and in the water. "There is so much variability in the composition at different elevations, we've hit a jackpot," said John Grotzinger, of Caltech in Pasadena, California. He and other members of Curiosity's science team presented an update about the mission Tuesday, Dec. 13, in San Francisco during the fall meeting of the American Geophysical Union. As the rover examines higher, younger layers, researchers are impressed by the complexity of the lake environments when clay-bearing sediments were being deposited, and also the complexity of the groundwater interactions after the sediments were buried. "A sedimentary basin such as this is a chemical reactor," Grotzinger said. "Elements get rearranged. New minerals form and old ones dissolve. Electrons get redistributed. On Earth, these reactions support life." Whether Martian life has ever existed is still unknown. No compelling evidence for it has been found. When Curiosity landed in Mars' Gale Crater in 2012, the mission's main goal was to determine whether the area ever offered an environment favorable for microbes. The crater's main appeal for scientists is geological layering exposed in the lower portion of its central mound, Mount Sharp. These exposures offer access to rocks that hold a record of environmental conditions from many stages of early Martian history, each layer younger than the one beneath it. The mission succeeded in its first year, finding that an ancient Martian lake environment had all the key chemical ingredients needed for life, plus chemical energy available for life. Now, the rover is climbing lower on Mount Sharp to investigate how ancient environmental conditions changed over time. "We are well into the layers that were the main reason Gale Crater was chosen as the landing site," said Curiosity Deputy Project Scientist Joy Crisp of NASA's Jet Propulsion Laboratory, in Pasadena, California. "We are now using a strategy of drilling samples at regular intervals as the rover climbs Mount Sharp. Earlier we chose drilling targets based on each site's special characteristics. Now that we're driving continuously through the thick basal layer of the mountain, a series of drill holes will build a complete picture." Four recent drilling sites, from "Oudam" this past June through "Sebina" in October, are each spaced about 80 feet (about 25 meters) apart in elevation. This uphill pattern allows the science team to sample progressively younger layers that reveal Mount Sharp's ancient environmental history. One clue to changing ancient conditions is the mineral hematite. It has replaced less-oxidized magnetite as the dominant iron oxide in rocks Curiosity has drilled recently, compared with the site where Curiosity first found lakebed sediments. "Both samples are mudstone deposited at the bottom of a lake, but the hematite may suggest warmer conditions, or more interaction between the atmosphere and the sediments," said Thomas Bristow of NASA Ames Research Center, Moffett Field, California. He helps operate the Chemistry and Mineralogy (CheMin) laboratory instrument inside the rover, which identifies minerals in collected samples. Chemical reactivity occurs on a gradient of chemical ingredients' strength at donating or receiving electrons. Transfer of electrons due to this gradient can provide energy for life. An increase in hematite relative to magnetite indicates an environmental change in the direction of tugging electrons more strongly, causing a greater degree of oxidation in iron. Another ingredient increasing in recent measurements by Curiosity is the element boron, which the rover's laser-shooting Chemistry and Camera (ChemCam) instrument has been detecting within mineral veins that are mainly calcium sulfate. "No prior mission has detected boron on Mars," said Patrick Gasda of the U.S. Department of Energy's Los Alamos National Laboratory, Los Alamos, New Mexico. "We're seeing a sharp increase in boron in vein targets inspected in the past several months." The instrument is quite sensitive; even at the increased level, boron makes up only about one-tenth of one percent of the rock composition. Boron is famously associated with arid sites where much water has evaporated away—think of the borax that mule teams once hauled from Death Valley. However, environmental implications of the minor amount of boron found by Curiosity are less straightforward than for the increase in hematite. Scientists are considering at least two possibilities for the source of boron that groundwater left in the veins. Perhaps evaporation of a lake formed a boron-containing deposit in an overlying layer, not yet reached by Curiosity, then water later re-dissolved the boron and carried it down through a fracture network into older layers, where it accumulated along with fracture-filling vein minerals. Or perhaps changes in the chemistry of clay-bearing deposits, such as evidenced by the increased hematite, affected how groundwater picked up and dropped off boron within the local sediments. "Variations in these minerals and elements indicate a dynamic system," Grotzinger said. "They interact with groundwater as well as surface water. The water influences the chemistry of the clays, but the composition of the water also changes. We are seeing chemical complexity indicating a long, interactive history with the water. The more complicated the chemistry is, the better it is for habitability. The boron, hematite and clay minerals underline the mobility of elements and electrons, and that is good for life."


Heuss-Assbichler S.,Ludwig Maximilians University of Munich | Magel G.,CheMin GmbH | Fehr K.T.,Ludwig Maximilians University of Munich
Waste Management | Year: 2010

Long-term hydrogen generation was observed in a Bavarian mono-landfill for municipal solid waste incineration (MSWI) residues. Hydration reactions of non-noble metals, especially aluminum, predominantly produce hydrogen at alkaline reaction conditions. Microscopic investigations show that aluminum metal may occur in different forms: as larger single grains, as small particles embedded in a vitrified matrix or less frequently in blowholes together with metallic silica.Four types of corrosion texture were observed, indicating different reaction mechanisms: aluminum hydroxide rims caused by hydration reactions at alkaline reaction conditions (reaction type 1) and multiphase rims with ettringite and hydrocalumite due to the reaction of aluminum hydroxide with sulfate and chloride ions which are solved in the pore water (reaction type 2). Galvanic corrosion textures due to the electric potential difference between aluminum and embedded intermetallic Fe- or Cu-rich exsolution phases lead to two further corrosion textures: Strong hydration effects of aluminum except a border of aluminum remnant directly beside the Fe- or Cu-rich segregations were only observed in fresh samples (reaction type 3). The reaction type 4 shows a network of Al-hydroxide veins occurring along the embedded intermetallic Fe- or Cu-rich exsolution segregation pattern within the metallic aluminum grain. Metal particles enclosed in vitrified particles offers the potential for future corrosion processes.The occurrence of corrosion types 1, 2 and 3 in fresh bottom ashes indicates that these reaction mechanisms predominate during the first reaction period in the presence of chlorine in an alkaline solution. Corrosion type 4, however, was additionally observed in aged samples. Here aluminum acts as sacrificed anode implying electrochemical reaction due to electrolytic pore water. Chloride in the system keeps the reaction alive as Al-hydroxide is solved which normally builds a protection shield around the aluminum metal particles.Due to field observations and experimental results we have reasonable indications that after an initial strong formation of hydrogen the reaction time for hydrogen production in the landfill is lengthened for several decades by the presence of chloride in the alkaline pore water. © 2010 Elsevier Ltd.


News Article | December 21, 2015
Site: www.techtimes.com

NASA's Curiosity rover has detected a substantial amount of silica deposits in the Martian rock formations it had investigated in the past seven months. Scientists believe this discovery provides evidence that water activity could likely have existed on the Red Planet in the past. In a press conference held during the meeting of the American Geophysical Union (AGU) in San Francisco, researchers involved in the Mars mission reported that the rover found higher silica concentrations in some of the areas it had surveyed in the past few months than in any of the sites it had visited before. The team discovered that as much as nine-tenths of the rocks the rover had examined were composed of silica. Jens Frydenvang, a researcher from the Los Alamos National Laboratory and one of those analyzing the Curiosity's findings, said that while they are still trying to determine how the rocks were enriched with silica, many of their hypotheses point to the possibility that Mars experienced considerable water activity in the past. He explained that areas with high silica deposits on Earth typically make suitable environments for sustaining microbial life-forms. Frydenvang added that the discovery of silica in the Martian rocks has led the scientists to make a rare backtrack in their research in order to investigate the new findings further. Traces of silica were first spotted while the Curiosity rover was approaching the region called "Marias Pass". The area is known to have a lower geological unit that makes contact with an overlying one. Curiosity's laser-firing instrument known as ChemCam detected high amounts of silica in a number of targets the probe had passed on its way to the designated contact zone. The rover continued to detect silica readings during its succeeding missions, which the scientists combined with elemental composition data from Curiosity's Alpha Particle X-Ray Spectrometer (APXS) and mineral data from its Chemistry and Mineralogy (CheMin) instrument. "What we're seeing on Mount Sharp is dramatically different from what we saw in the first two years of the mission," Ashwin Vasavada, a researcher from NASA's Jet Propulsion Laboratory, said. "There's so much variability within relatively short distances." "The silica is one indicator of how the chemistry changed. It's such a multifaceted and curious discovery, we're going to take a while figuring it out." The researchers are following two primary hypotheses to figure out recent findings made on Mount Sharp, both of which have water playing a crucial role. One of the hypotheses involves having acidic water carry away other elements from the rocks and leaving only the silica deposits behind. The other hypothesis features neutral or alkaline water dissolving silica and depositing them on the rocks through the resulting solution. The latest findings made by the Curiosity have interesting threads associated with data collected by NASA's earlier Spirit rover in another part of Mars. The probe detected traces of sulfuric acidity in the region. "Buckskin" is one of the Martian rocks analyzed by the Curiosity rover that contained evidence of the rare mineral tridymite. On Earth, tridymite is formed when metamorphic or igneous rocks are exposed to high temperatures. The fine layers of sedimentary rocks the rover detected the mineral on, however, showed evidence that they may have been part of lakebed deposits. This proves that a magmatic evolution could likely have occurred on Mars.

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