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MSL - ChemCam Science Reports
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MSL's ChemCam characterizes Martian Dust
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April 11, 2013
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The ChemCam Instrument aboard the Mars Science Laboratory Rover has continued operations on Mars, firing thousands of laser shots to perform Laser-Induced Breakdown Spectroscopy to determine the elemental composition of a variety of targets. Recently, ChemCam Data was presented focusing on wind-deposited dust that is transported through the Martian Atmosphere and spread across the entire planet.
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Everything on Mars, whether it’s a natural feature or an artificial object like Curiosity, will sooner or later be covered with a thin layer of wind-deposited red dust. This means that every target of ChemCam includes Martian Dust that is analyzed in the first several laser shots before the layer of dust is removed by the laser.
The two frames shown in the image to the right were taken a few minutes apart on Sol 84. In between the ChemCam instrument fired its laser 300 times in 10 bursts of 30 shots along a vertical line. The right frame shows that a 7-millimeter stripe of dust was removed. The laser beam itself has a diameter of about half a millimeter, but small pressure waves that are generated when the laser hits the rock are capable of removing dust from a larger area. This enables ChemCam to analyze the underlying rock once the dust is removed, but it also allows the instrument to take a close look at the dust itself. |
Image: NASA/JPL-Caltech/LANL/CNES/IRAP/LPGNantes/CNRS/IAS
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Image: NASA/JPL-Caltech/LANL/CNES/IRAP/LPGNantes/CNRS/IAS
The spectrum shown above has been acquired by ChemCam when performing active spectroscopy on its graphite Calibration Target back on Sol 27. It shows two spectra that were combined in a single image – one from the first laser shot when a large amount of dust was still present on the target and one from shot 50 when all dust was removed. This enables scientists to learn more about the dust.
"We knew that Mars is red because of iron oxides in the dust," said ChemCam Deputy Principal Investigator Sylvestre Maurice of the Institut de Recherche en Astrophysique et Planétologie in Toulouse, France. "ChemCam reveals a complex chemical composition of the dust that includes hydrogen, which could be in the form of hydroxyl groups or water molecules."
The spectrum shows an abundance of magnesium (Mg), silicon (Si), calcium (Ca), aluminum (Al), potassium (K), oxygen (O), hydrogen (H), and carbon (C) in the dust. The carbon and oxygen lines are due to the graphite (carbon) target and the Carbon Dioxide that is present in the Martian atmosphere.
"We knew that Mars is red because of iron oxides in the dust," said ChemCam Deputy Principal Investigator Sylvestre Maurice of the Institut de Recherche en Astrophysique et Planétologie in Toulouse, France. "ChemCam reveals a complex chemical composition of the dust that includes hydrogen, which could be in the form of hydroxyl groups or water molecules."
The spectrum shows an abundance of magnesium (Mg), silicon (Si), calcium (Ca), aluminum (Al), potassium (K), oxygen (O), hydrogen (H), and carbon (C) in the dust. The carbon and oxygen lines are due to the graphite (carbon) target and the Carbon Dioxide that is present in the Martian atmosphere.
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This and many more dust measurements were used to put the dust into a chemical context. The graph to the right shows how materials analyzed by ChemCam during the first 100 Sols differed with regard to hydrogen content (x-axis) and alkali (y-axis). Rocks that were analyzed show a variety of compositions – highly alkaline, neutral and less alkaline rocks were found. All rocks were characterized by a low signal for hydrogen.
Martian soils, however, are characterized by a dynamic range in both alkali and hydrogen content. ChemCam data shows that there are two soil components and a mechanical mixing line between them. Coarse-grained soils are more alkaline while having a low hydrogen content and fine-grained soils are characterized by low alkali and high hydrogen. Coarse-grained soils are likely fragments of rocks that were deposited as part of an alluvial fan from Peace Vallis on the north rim of Gale Crater while finer soils are wind-deposited materials. The dust composition as measured by ChemCam resembles that of fine soils with low alkali and high hydrogen. |
Image: NASA/JPL-Caltech/LANL/CNES/IRAP/LPGNantes/CNRS/IAS
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ChemCam results of general compositional analysis of targets along the rover traverse have also been published. All major elements were regularly reported along with minor and trace elements. In the graph below, the mean Silicon Dioxide and Iron(III) Oxide contents are shown.
Credit: Wiens et al., COMPOSITIONS DETERMINED BY CHEMCAM ALONG CURIOSITY’S TRAVERSE FROM
BRADBURY STATION TO GLENELG IN GALE CRATER, MARS, 2013
The graph shows a highly variable SiO2 contents in the regions near MSL’s landing site, for both rocks and soil. This is being interpreted as a result of sampling with varying individual minerals in coarse-grained heterogeneous rocks and pebbles. SiO2 abundance near the landing site was ~40% up to more than 60% which is expected for alkali feldspars. The highest SiO2 contents measured point to the presence of quartz.
As MSL traversed beyond the Anton Target represented by a red dashed line in the image, the overall compositions showed a change. High abundances of SiO2 became rare and more wind-deposited soils were encountered. Fine soils show an SiO2 abundance of 40-50%. Iron Oxide levels showed a slight increase and typically, rocks showed at least a 20% Iron Oxide content while soils feature lower content.
Additionally, ChemCam analysis showed an anti-correlation between Silicon Dioxide and Calcium Oxide.
As MSL traversed beyond the Anton Target represented by a red dashed line in the image, the overall compositions showed a change. High abundances of SiO2 became rare and more wind-deposited soils were encountered. Fine soils show an SiO2 abundance of 40-50%. Iron Oxide levels showed a slight increase and typically, rocks showed at least a 20% Iron Oxide content while soils feature lower content.
Additionally, ChemCam analysis showed an anti-correlation between Silicon Dioxide and Calcium Oxide.
Photo: NASA/JPL/Caltech/MSSS
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Another feature of ChemCam that is being increasingly used is its ability to obtain depth profiles. Small-scale depth profiles are acquired by the instrument itself as each laser shot ablates about 0.5 micrometers of any given target, but with other MSL instruments, ChemCam can provide actual profiles of the uppermost surface layer. At Rocknest, ChemCam was used to analyze the differently colored layers observed in the scoop trenches.
More recently, ChemCam was used to analyze a number of spots at different depths inside the first hole drilled by the Curiosity Rover. For that, ChemCam fired its laser at the wall of the 1.6-centimeter wide hole to perform active spectroscopy at different depths. This enables scientists to learn more about the uppermost layer of the John Klein rock and gain insight into weathering processes that might have influenced the rock surface over the course of its evolution. |
Curiosity's ChemCam takes a closer Look at Martian Veins
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January 16, 2013
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To complement the visual observation of geological features made by Curiosity’s Mast Cameras and the Mars Hand Lens Imager, the Mars Science Laboratory mission has continued extensive ChemCam operations – relying on the instrument to provide a quick way of determining the elemental composition of rocks without planning any complicated robotic sequences. To date, more than 25,000 laser shots have been fired on Mars to support Laser-Induced Breakdown Spectroscopy that is conducted by ChemCam. The Remote-Micro Imager of the instrument has been used extensively to provide context images of laser targets, but also to make close-up observations of rock targets.
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After MastCam and MAHLI imagery revealed fractured rocks with veins, teams wanted to know more about their composition and started targeted ChemCam observations focused on these small veins. Veins are created when water containing minerals can percolate through fractured rocks, allowing minerals to precipitate out, filling in the fractures. Veins found in Yellowknife Bay, a depression inside the Glenelg area that Curiosity is currently exploring, are light-toned in texture. Visual observations can not provide the exact chemical composition of the veins, but ChemCam can determine the elemental composition of targets that are as small as 0.35 millimeters, which is the size of the instrument’s laser beam.
The ChemCam Science team provided two spectra of two different targets. The top half of the image to the right shows a close-up image of ‘Crest,’ a target featuring a prominent vein. The spectrum of Crest is shown in red color while the spectrum of a known basaltic target is shown in black. Crest was examined back on Sol 125, December 13, 2012. The second target shown in this image is a bright vein in a target named ‘Rapitan.’ The spectral signature of this vein is shown in blue while the black spectrum represents that of the basalt reference target. Rapitan was analyzed on Sol 135, December 23, 2012. Both spectra show that the veins are unlike the typical basaltic material as the red/blue spectra show a different signature than the black reference spectrum. The minerals in the veins are rich in Calcium, as shown by the two large peaks in both spectra, and depleted in Silica and Magnesia in comparison with basaltic targets. For Crest, ChemCam picked up faint signals for Aluminum. |
Image: NASA/JPL-Caltech/LANL/CNES/IRAP/LPGNantes/CNRS
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Image: NASA/JPL-Caltech/LANL/CNES/IRAP/LPGNantes/CNRS
The second graphic shows the faint peaks representing Sulfur and Hydrogen. The Sulfur emission lines can be seen in the left graphic for both targets, Crest and Rapitan, while the basaltic reference target does not contain Sulfur. The right graph shows that the veins contain Hydrogen which points to hydrated minerals. Scientists believe that the veins contain hydrated calcium sulfates possibly gypsum or bassanite. “Earth, calcium sulfates like gypsum form frequently in veins when relatively dilute fluid circulates at low to moderate temperatures,” NASA said in a statement.
Visually, Martian veins and veins found here on Earth have a very similar appearance as the image below clearly shows. The image to the left is a Remote-Micro Imager mosaic that was taken on Sol 126 showing a view of the Sheepbed Rock in Yellowknife Bay. The lowest layer of fractured rocks inside Yellowknife Bay has been named Sheepbed unit. The sulfate-rich veins are about 1 to 5 millimeters wide. The right image (courtesy of Pierre Thomas) shows veins found in the Egyptian desert on Earth.
Visually, Martian veins and veins found here on Earth have a very similar appearance as the image below clearly shows. The image to the left is a Remote-Micro Imager mosaic that was taken on Sol 126 showing a view of the Sheepbed Rock in Yellowknife Bay. The lowest layer of fractured rocks inside Yellowknife Bay has been named Sheepbed unit. The sulfate-rich veins are about 1 to 5 millimeters wide. The right image (courtesy of Pierre Thomas) shows veins found in the Egyptian desert on Earth.
Image: NASA/JPL-Caltech/LANL/CNES/IRAP/LPGNantes/CNRS/LGLyon/Planet-Terre
Jake Matijevic Rock holds big Surprise for MSL Investigators |
October 12, 2012 |
Photo: NASA/JPL/Caltech/MSSS
Jake Matijevic
Red Dots: ChemCam Observation Points Purple Circles: APXS Integration Locations |
The Mars Science Laboratory Science Team and ChemCam Team have presented the first results of the ChemCam examination of the Jake Matijevic Rock performed on Sols 45 and 48 of Curiosity's surface mission. Teams and scientists were surprised by the data returned by ChemCam and APXS (Alpha-Particle X-Ray Spectrometer) showing that the rock was not quite what it was expected to be, a homogeneous, basaltic rock. ChemCam itself is working as expected and has already fired more than 5,000 laser shots at about 30 different targets.
Jake Matijevic was selected to be the first target of MSL's Contact Instruments APXS and MAHLI, but the rock was also examined by the MastCameras to provide the opportunity of visual assessments and the ChemCam Laser Spectrometer to provide additional information and to cross-calibrate APXS and ChemCam. The rock is about 25 centimeters tall and 40 centimeters wide giving Curiosity the opportunity to conduct contact science which requires the robotic arm to push its instruments against the rock. This first contact science target has been named "Jake Matijevic" in honor of Jacob Matijevic (1947-2012) who was the surface operations systems chief engineer for the Mars Science Laboratory Mission. |
Matijevic was also a leading engineer on all the previous rovers, making major contributions to rover technology and paving the way for the operation of rovers on Mars.
ChemCam performed a number of analysis of the target. On Sol 45, a linear five-point pattern was targeted by ChemCam and on Sol 48, the instrument shot its laser at a total of 9 points in a three-by-three grid. 30 laser pulses were fired at each observation point, the first five spectra were discarded to allow the instrument to clear surface dust while the next 25 spectra were used for analysis. A total of 350 spectra were provided by ChemCam.
ChemCam performed a number of analysis of the target. On Sol 45, a linear five-point pattern was targeted by ChemCam and on Sol 48, the instrument shot its laser at a total of 9 points in a three-by-three grid. 30 laser pulses were fired at each observation point, the first five spectra were discarded to allow the instrument to clear surface dust while the next 25 spectra were used for analysis. A total of 350 spectra were provided by ChemCam.
Taking a close look at Jake Matijevic
Animation: NASA/JPL/Caltech/Spaceflight101
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The animated graphic to the right shows all 350 spectra plotted along three axes in terms of its first three principal components. The different colors represent the individual observation points. "Each observation point has a unique composition and all spectra cluster into that unique composition," said Roger Wiens, ChemCam principal investigator.
This clearly shows that each of the 14 points had a different composition - which implies that mineral grains in Jake are in many cases larger than the 0.35-millimeter diameter of the laser beam. For ChemCam, spectra from different points in a small area would either suggest very large mineral grains with laser beams hitting the same grain or it could also suggest very small grains so that the ChemCam spectra always show an average of the composition. Seeing different spectra indicated that grain-sizes are about the size of the laser beam. Teams were targeting a fine-grained rock to be the first Contact Science Target, but what they got was a target presenting a larger scientific challenge with Jake being a coarse-grained rock. |
Image: NASA/JPL-Caltech/LANL/IRAP/UNM
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Image: NASA/JPL-Caltech/LANL/IRAP
These four spectra represent the composition of different observation points on Jake showing that each of the points had a different composition. The spectra shown are average spectra generated by all 25 pulses at each of the points, except for the spectrum at the bottom. For that, the average of shots 21 to 30 was used. (The colors of the individual spectra correspond to that of the 3D plot above.) The spectra are covering the ultraviolet region of the spectrum as well as infrared and visible light for the alkaline metal peaks.
The 45-1 spectrum shows a high abundance of magnesium and iron which is suggestive of the mineral olivine, (Mg, Fe)2SiO4. Spectrum 45-2 is very rich of iron and titanium which suggests that a metal oxide grain was hit, possibly ilmenite, FeTiO3. The 48-10 spectrum shows peaks for silicon, aluminum, sodium and potassium which is characteristic for the mineral feldspar (alkali feldspar: KAlSi3O8, (K,Na)AlSi3O8 ...) and the 48-14 spectrum is rich in calcium and magnesium which suggests the mineral group pyroxene, in this case likely diopside, CaMgSi2O6.
The 45-1 spectrum shows a high abundance of magnesium and iron which is suggestive of the mineral olivine, (Mg, Fe)2SiO4. Spectrum 45-2 is very rich of iron and titanium which suggests that a metal oxide grain was hit, possibly ilmenite, FeTiO3. The 48-10 spectrum shows peaks for silicon, aluminum, sodium and potassium which is characteristic for the mineral feldspar (alkali feldspar: KAlSi3O8, (K,Na)AlSi3O8 ...) and the 48-14 spectrum is rich in calcium and magnesium which suggests the mineral group pyroxene, in this case likely diopside, CaMgSi2O6.
Image: NASA/JPL-Caltech/LANL/IRAP/SSI
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The 48-14 target was analyzed further. "We took the 30 laser shots in that particular cluster and we plotted the calcium- and magnesium oxide abundances against each other," Wiens said. The graphic to the left shows the abundances of these constituents as a function of the laser shot number - sowing a linear connection.
"The laser beam was excavating right into what we think is a pyroxene mineral grain and so the abundances of these two elements was going up as we walked right into this mineral grain. That was very interesting to see," Wiens noted. "ChemCam has seen unexpected compositions ever since its third observation which was way back on Sol 15. As we started to build up the statistics from different analysis points, the picture became more clear. Many of the pebbles as well as some of these larger rocks have compositions that are high in silicon, and in alkaline elements including sodium, potassium and rubidium." Discovering feldspar on Mars was a surprise for scientists and that is why teams were very careful before announcing their findings - waiting to get more readings from more than a few targets. |
Scientists examined the spectra of Jake Matijevic obtained with ChemCam and the two integrations of the APXS instrument along with supporting images of MAHLI and the MastCams to investigate the conditions of its formation.
Jake Matijevic in particular is very low in nickel and zinc, low in magnesium and iron, but rich in sodium, aluminum, silicon and potassium, when comparing it to other rocks that were analyzed on Mars.
With Jake Matijevic presenting a more varied composition than expected from previous missions like the Mars Exploration Rovers, the scientists had their first real surprise of the mission as the Rock was something new that was found on Mars and it also became clear that the rock resembles an unusual-type of rock that is found in only a few spots on Earth.
Jake Matijevic in particular is very low in nickel and zinc, low in magnesium and iron, but rich in sodium, aluminum, silicon and potassium, when comparing it to other rocks that were analyzed on Mars.
With Jake Matijevic presenting a more varied composition than expected from previous missions like the Mars Exploration Rovers, the scientists had their first real surprise of the mission as the Rock was something new that was found on Mars and it also became clear that the rock resembles an unusual-type of rock that is found in only a few spots on Earth.
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"This rock is a close match in chemical composition to an unusual but well-known type of igneous rock found in many volcanic provinces on Earth," said Edward Stolper of the California Institute of Technology in Pasadena, who is a Curiosity co-investigator. "With only one Martian rock of this type, it is difficult to know whether the same processes were involved, but it is a reasonable place to start thinking about its origin."
If Jake Matijevic is indeed a rock of this type, it would mean that it formed from a rock melt that evolved from a water-rich magma due to crystallization processes in planet's mantle beneath the crust at an elevated pressure. Magma rising to the surface and starting to cool causes certain elements to crystallize out of the material, leaving a fluid magma that is enriched with left-behind components. Taking a melted rock, or magma, and allowing it to cool in a certain environment will result in a fractional crystallization process during which different minerals crystallize out at different times in the process, leading to a different composition of the melt which eventually forms rocks. The cooling conditions are giving the rock its mineral characteristics, physical and chemical properties, and appearance. |
Photo: NASA/JPL/Caltech/MSSS
MAHLI Close-Up of Jake
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Scientists were surprised to find an alkali basalt rock on Mars which broadens the spectrum of basalts found on Mars. "This is a rock-type that has never been found before (on Mars)," Stolper said. This type of basalt can be contrasted with basalts that were already studied such as basalts on Mars being examined by the Mars Exploration Rovers, or basalts coming from Mars to Earth as meteorites. After initial analysis, is clear that this type of basalt is different from those found at MER sites or in Martian meteorites. This new data has to be expanded to provide more information on what Mars looked like in the past and what kind of igneous rock-formation
ChemCam acquires first Spectra of Martian Samples & discovers Basalt |
Aug. 22, 2012 |
Photo: ChemCam/LANL/IRAP/CNES
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The Mars Science Laboratory ChemCam - Chemistry and Camera Instrument has started operations at the surface of Mars following initial electrical checkouts and instrument testing after Curiosity's landing on August 6, 2012. Initial Science Data of a series of targets near the landing site was acquired by both ChemCam components - the Laser-Induced Breakdown Spectrometer and the Remote-Micro Imager. However, full instrument characterization and cross-calibration with the Alpha-Particle Spectrometer have yet to be done over the next several weeks of Rover operation on Mars to achieve the full instrument performance.
ChemCam is an instrument package that consists of two remote sensing elements – The Laser-Induced Breakdown Spectrometer (LIBS) and a Remote Micro-Imager (RMI). LIBS provides elemental compositions of samples while the RMI puts the analyses done by LIBS into a geomorphologic context. For more information on ChemCam, refer to our Instrument Overview Site. |
As part of ChemCam instrument commissioning, active and passive spectroscopy was performed on the instrument's calibration target on the back of the Rover that includes a laser-target and other targets that are of known composition to obtain test-spectra in the Martian Environment. Before starting to fire at soil samples, ChemCam used its LIBS Laser to fire at its calibration target leaving a new visible mark. The targets that have a known composition will be used over the course of the mission to verify the performance of the spectrometers after extended periods of time on the Martian Surface.
Credit: NASA/JPL/LANL/Spaceflight101
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The first target of ChemCam was selected by the Instrument Team to perform a target exercise on a Rock close to the Rover with a nice flat surface. Teams chose a target 'N165' which was later named Coronation. The Coronation sample is a fist-sized rock that was believed to be of basaltic origin. On August 19, 2012, Curiosity fired 30 pulses of its laser at the rock during a 10-second period with the LIBS Telescope registering the wavelengths of the glowing plasma that is created when the high-energy laser pulses hit the target. LIBS operated at its nominal pulse-rate of 3 Hertz for this analysis, but it is capable of operating anywhere between 1 and 10Hz. Three spectrometers analyze the spectrum that is observed to deduce the elemental composition of the sample. The intensity of a total of 6,144 different wavelengths from infrared to ultraviolet light is recorded. The test was completed successfully, all 30 spectra were recorded properly and have been downlinked to Earth for analysis. In addition, the ChemCam team was pleased to see one of their hypotheses get confirmed with the first analysis. At Mars, the plasma flash created by the laser is not appearing as compressed as it does on Earth because of the properties of the Martian Atmosphere that has an average surface pressure of 0.64 Kilopascals (Earth: 101.3kPa). In addition, plasmas created on Mars are more brilliant than those observed at higher pressures. This enables the LIBS Instrument to record better data sets on Mars when comparing data-to-noise-ratios of Earth and Mars. "It's surprising that the data are even better than we ever had during tests on Earth, in signal-to-noise ratio," said ChemCam Deputy Project Scientist Sylvestre Maurice of the Institut de Recherche en Astrophysique et Planetologie (IRAP) in Toulouse, France.
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Photo: NASA/JPL/LANL
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N165 Context Image
Image: NASA/JPL/Caltech
The composite image below to the left illustrates the ChemCam test. The background is a large NavCam frame that shows the context of the target. The Circular Inset is an image of the Coronation Rock that was taken by the Remote Micro Imager before the rock was hit with the laser.The area shown in the inset is 6 centimeters in diameter. The square inset is also an RMI Image. It is a combined image of before and after shots with before shots being subtracted to make the small mark the laser left visible. The diameter of the area this inset is covering is 8 millimeters. This first target exercise of ChemCam was a complete success. "We got a great spectrum of Coronation -- lots of signal," said ChemCam Principal Investigator Roger Wiens of Los Alamos National Laboratory, N.M. "Our team is both thrilled and working hard, looking at the results. After eight years building the instrument, it's payoff time!"
Image: NASA/JPL-Caltech/LANL/CNES/IRAP
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Credit: LANL
Comparing Plasma Appearance in a Martian Environment and on Earth
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This is ChemCam's first Spectrum that was acquired during the analysis of Coronation. The spectrum shows the elemental composition of Coronation with the background of the Martian Atmosphere. It shows all 6,144 channels from 240 to 850 nanometers covering ultraviolet, visible and infrared light.
Credit: NASA/JPL-Caltech/LANL/CNES/IRAP
"We actually saturated one emission line, Oxygen, just slightly, so that just shows what good signal we are getting from Mars," Wiens said. A number of emission lines are labeled in this spectrum showing the composition of Coronation. The major elements shown in the spectrum are Oxygen, Silicon, Magnesium, Iron, Sodium, Potassium, Calcium and Aluminum. It has to be noted, that the heights of the peaks do not directly indicate the relative abundances of the elements in the rock, as some emission lines are more easily excited than others which has to be corrected during data processing.
The spectrum shows that LIBS can pick up minor elements. The inset to the left covers wavelengths of 398 to 404 nanometers showing the low-abundance elements Titanium and Manganese. Lithium is also prominent in the spectrum which is only present in traces estimated at about 50 parts per million. Another very interesting aspect of this analysis is shown in the other inset to the right. This inset shows the peaks of Hydrogen and Carbon during all 30 pulses. The Carbon peak remains constant because it is related to the Martian Atmosphere that has to be factored into the analysis. It consists of 95% Carbon Dioxide explaining the high abundance of Carbon and Oxygen in the spectrum. The Hydrogen peak was only present on the first laser shot with a small trace during the second pulse before vanishing from the spectrum. This indicated that Hydrogen was only present in the uppermost layer of N165 that was penetrated by the first laser pulses. Teams are analyzing this aspect of initial Hydrogen abundance which could be related to a thin layer of dust at the surface of the rock consisting of a different material than the rock itself. Magnesium was also slightly enriched on the surface. These two elements were also present at different location such as the calibration target of the rover indicating that is is indeed related to Martian Dust.
In conclusion, teams were able to confirm that Coronation was indeed an igneous basalt.
The spectrum shows that LIBS can pick up minor elements. The inset to the left covers wavelengths of 398 to 404 nanometers showing the low-abundance elements Titanium and Manganese. Lithium is also prominent in the spectrum which is only present in traces estimated at about 50 parts per million. Another very interesting aspect of this analysis is shown in the other inset to the right. This inset shows the peaks of Hydrogen and Carbon during all 30 pulses. The Carbon peak remains constant because it is related to the Martian Atmosphere that has to be factored into the analysis. It consists of 95% Carbon Dioxide explaining the high abundance of Carbon and Oxygen in the spectrum. The Hydrogen peak was only present on the first laser shot with a small trace during the second pulse before vanishing from the spectrum. This indicated that Hydrogen was only present in the uppermost layer of N165 that was penetrated by the first laser pulses. Teams are analyzing this aspect of initial Hydrogen abundance which could be related to a thin layer of dust at the surface of the rock consisting of a different material than the rock itself. Magnesium was also slightly enriched on the surface. These two elements were also present at different location such as the calibration target of the rover indicating that is is indeed related to Martian Dust.
In conclusion, teams were able to confirm that Coronation was indeed an igneous basalt.
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"After (analysing) this rock, we (the ChemCam Team) told the science team that they were free to start choosing some targets," Wiens noted. The MSL Science Team selected the Goulburn Scour as the primary science target at the MSL Landing Site. The four scours near the landing site are excavation areas that were caused by Mars Landing Engine Plume Impingement during the landing sequence that revealed sub-surface material. The Goulburn Scour presents the greatest collection of sub-surface material. The uppermost layer of the area contains fragments of rock that are embedded in a matrix of finer material. Shown in the inset are pebbles up to about 3 centimeters across (refer to the upper two arrows in the image) and a larger clast 11.5 centimeters long protruding up from the layer in which it is embedded in. The mechanisms of formation of clast-rich sedimentary layers can be distinguished by the size, shape, surface textures and positioning with respect to each other of the fragments in the different layers.
Goulburn was examined with ChemCam's Remote-Micro Imager acquiring imagery of six locations in the scour to provide a close-up view of the materials for analysis by scientists. The locations of the RMI Images are shown in the graphic below that uses a MastCam34 Photo to provide context to the small close-ups. Locations 2, 3 and 4 were also examined with the LIBS Instrument and its laser. |
Photo: NASA/JPL/MSSS
White-Balanced Image of Goulburn Scour
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Credit: NASA/JPL/LANL/MSSS
The Laser was fired at the Center of the particular images. "The results we got there are pretty consistent with what we saw on Coronation," Wiens explained. This is not coming as a big surprise as basalt is the major igneous rock on Mars. The countless clasts featured in the MRI images also appear to be basalts that ended up in sedimentary rock that loosely cemented those igneous fragments.
ChemCam was also used on other rocks in the vicinity of the Rover showing mostly consistent results with one sample showing a slightly different composition. This sample has also been identified as an igneous rock fitting perfectly into the context of MSL's landing site that has not presented any scientific surprises yet. "Where are looking forward to doing more science with the ChemCam instrument, but we're excited that it is looking great so far," Roger Wiens noted.
ChemCam will be undergoing wavelength calibrations over the coming weeks to achieve its full sensibility at all the channels. Teams are using a library of spectra that was created using the flight hardware before it was integrated into the rover to provide additional instrument characterization. The initial spectra can be taken as qualitative analysis before quantitative assessments will be provided later into the mission when instrument calibrations are complete. To further improve the performance of the data processing techniques, cross-calibrations with the Alpha-Particle Spectrometer Instrument on the Rover's Robotic Arm will be made to provide characterization for both instruments.
ChemCam was also used on other rocks in the vicinity of the Rover showing mostly consistent results with one sample showing a slightly different composition. This sample has also been identified as an igneous rock fitting perfectly into the context of MSL's landing site that has not presented any scientific surprises yet. "Where are looking forward to doing more science with the ChemCam instrument, but we're excited that it is looking great so far," Roger Wiens noted.
ChemCam will be undergoing wavelength calibrations over the coming weeks to achieve its full sensibility at all the channels. Teams are using a library of spectra that was created using the flight hardware before it was integrated into the rover to provide additional instrument characterization. The initial spectra can be taken as qualitative analysis before quantitative assessments will be provided later into the mission when instrument calibrations are complete. To further improve the performance of the data processing techniques, cross-calibrations with the Alpha-Particle Spectrometer Instrument on the Rover's Robotic Arm will be made to provide characterization for both instruments.
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