Engineering topics

Castle, N.

Publications and source records attributed to Castle, N..

9 records

NASA NTRS2020

Glen Torridon Mineralogy and the Sedimentary History of the Clay Mineral Bearing Unit

Clay minerals are common in ancient terrains on Mars and their presence at the surface alludes to aqueous processes in the Noachian to Early Hesperian (>3.5 Ga). Gale crater was selected as Curiosity’s landing site largely because of the identification of clay mineral rich strata from orbit. On Earth, the types of clay minerals (i.e., smectites) identified in Gale crater are typically juvenile weathering products that ultimately record the interaction between primary igneous minerals with the hydrosphere, atmosphere, and biosphere. Trioctahedral and dioctahedral smectite were identified by Curiosity in units stratigraphically below the Clay Mineral-Bearing Unit (CBU) identified from orbit. Compositional and sedimentological data suggest the smectite formed via authigenesis in a lake environment and may have been altered during early diagenesis. The CBU is stratigraphically equivalent to a hematite-rich unit to the north and stratigraphically underlies sulfate-rich units to the south, suggesting a dynamic environment and evolving history of water in the ancient Gale crater lake. Targeting these clay mineral rich areas on Mars with rover missions provides an opportunity to explore the aqueous and sedimentary history of the planet.

Thorpe, M. T.↗

NASA NTRS2020

Mineralogy of Vera Rubin Ridge in Gale Crater from the Mars Science Laboratory CheMin instrument

Gale crater was selected as the landing site for the Mars Science Laboratory Curiosity rover because of orbital evidence for a variety of secondary minerals in the lower slopes of Aeolis Mons (aka Mount Sharp) that indicate changes in aqueous conditions over time. Distinct units demonstrate orbital spectral signatures of hematite, phyllosilicate (smectite), and sulfate minerals, which suggest that ancient aqueous environments in Gale crater varied in oxidation potential, pH, and water activity. Vera Rubin ridge (VRR) is the first of these units identified from orbit to have been studied by Curiosity. Orbital near-infrared data from VRR show a strong band at 860 nm indicative of hematite. Before Curiosity arrived at VRR, the hypotheses to explain the formation of hematite included (1) precipitation at a redox interface where aqueous Fe2+ was oxidized to Fe3+, and (2) acidic alteration of olivine in oxic fluids. Studying the composition and sedimentology of the rocks on VRR allow us to test and refine these hypotheses and flesh out the depositional and diagenetic history of the ridge. Here, we focus on the mineralogical results of four rock powders drilled from and immediately below VRR as determined by CheMin.

Rampe, E. B.↗

NASA NTRS2019

The Mineralogical Record of Ancient Fluvio-Lacustrine Environments in Gale Crater as Measured by the MSL CheMin Instrument

The Mars Science Laboratory Curiosity rover landed in Gale crater in August 2012 to investigate early Hesperian-aged sedimentary rocks on the lower slopes of Aeolis Mons (i.e., Mount Sharp) that show variations in phyllosilicates, hematite, and sulfates from orbital reflectance spectroscopy, suggesting changes in ancient aqueous environments. During the Eighth International Conference on Mars in July 2014, Curiosity was still traversing the Bradbury group on the plains of Gale crater (Aeolis Palus) and had only analyzed four samples in its internal laboratories. Soon after Mars 8, Curiosity began its investigation of Mount Sharp and has since driven through ~350 m of vertical stratigraphy, the majority of which is part of the Murray formation. The Murray fm is comprised primarily of laminated mudstone with occasional sandstone and heterolithic facies and represents a long-lived fluvio-lacustrine environment. Curiosity has analyzed 13 drilled rock samples from the Murray formation and 4 from the ancient eolian Stimson fm with the Chemistry and Mineralogy (CheMin) instrument. Here, we discuss the mineralogy of all fluvio-lacustrine samples analyzed to date and what these results tell us about sources of the sediments, aqueous environments, and habitability of ancient Gale crater.

Rampe, E. B.↗

NASA NTRS2019

New Perspectives of Ancient Mars: Mineral Diversity and Crystal Chemistry at Gale Crater, Mars from the CheMin X-Ray Diffractometer

The Mars Science Laboratory Curiosity rover arrived at Mars in August 2012 with a primary goal of characterizing the habitability of ancient and modern environments. Curiosity landed in Gale crater to study a sequence of ~3.5 Ga old sedimentary rocks that, based on orbital visible/near-infrared reflectance spectra, contain secondary minerals that suggest deposition and/or alteration in liquid water. The sedimentary sequence that comprises the lower slopes of Mount Sharp within Gale crater may preserve a dramatic shift on early Mars from a relatively warm and wet climate to a cold and dry climate based on a transition from smectite-bearing strata to sulfate-bearing strata. The rover is equipped with cameras and geochemical and mineralogical instruments to examine the sedimentology and identify compositional changes within the stratigraphy. These observations provide information about variations in depositional and diagenetic environments over time. The Chemistry and Mineralogy (CheMin) instrument is one of two internal laboratories on Curiosity and includes a transmission X-ray diffractometer (XRD) and X-ray fluorescence (XRF) spectrometer with a Co-K source. CheMin measures loose sediment samples scooped from the surface and drilled rock powders. The XRD provides quantitative mineralogy of scooped and drilled samples to a detection limit of ~1 wt.%. Curiosity has traversed >20 km since landing and has primarily been exploring the site of a predominantly ancient lake environment fed by groundwater and streams emanating from the crater rim. Results from CheMin demonstrate an incredible diversity in the mineralogy of fluvio-lacustrine rocks that signify variations in source rock composition, sediment transport mechanisms, and depositional and diagenetic fluid chemistry. Abundant trioctahedral smectite and magnetite at the base of the section may have formed from low-salinity pore waters with a circumneutral pH within lake sediments. A transition to dioctahedral smectite, hematite, and Ca-sulfate going up section suggests a change to more saline and oxidative aqueous conditions within the lake waters themselves and/or within diagenetic fluids. The primary minerals detected in fluvio-lacustrine samples by CheMin also suggest diversity in the igneous source regions for the sediments, where abundant pyroxene and plagioclase in most samples suggest a basaltic protolith, but sanidine and pyroxene in one sample may have been sourced from a potassic trachyte, and tridymite and sanidine in another sample may have been transported from a rhyolitic source. Crystal chemistry of major phases in each sample have been calculated from refined unit-cell parameters, providing further constraints on aqueous alteration processes and igneous protoliths for the sediments. Perhaps one of the biggest mysteries revealed by the CheMin instrument is the high abundance of X-ray amorphous materials (15 to 73 wt.%) in all samples measured to date. X-ray amorphous materials were detected by CheMin based on the observation of broad humps in XRD patterns. How these materials formed, their composition, and why they persist near the martian surface remain a topic of debate. The sedimentology and composition of the rocks analyzed by Curiosity demonstrate that habitable environments persisted intermittently on the surface or in the subsurface of Gale crater for perhaps more than a billion years.

Rampe, E. B.↗

NASA NTRS2018

Using Mineralogy of the Bagnold Dune Field in Gale Crater to Interpret Eolian Sediment Sorting on the Martian Surface

The Mars Science Laboratory Curiosity rover landed in Gale crater in August 2012 to characterize modern and ancient surface environments. Curiosity executed a two-phase campaign to study the morphology, activity, physical properties, and chemical and mineralogical composition of the Bagnold Dune Field, an active eolian dune field on the lower slopes of Aeolis Mons (Mount Sharp). Detectable aspects of dune sand mineralogy have been examined from orbit with the visible/short-wave infrared spectrometer CRISMand the thermal-infrared spectrometers THEMIS and TES. CRISM data demonstrate variations in plagioclase, pyroxene, and olivine abundances across the dune field. Curiosity analyzed sediments from two locations in the dune field to evaluate the causes of the mineralogical differences observed from orbit. The Gobabeb sample was collected from Namib Dune, a barchanoidal dune on the upwind margin of the dune field, and the Ogunquit Beach sample was collected from the Mount Desert Island sand patch located downwind from Namib. These samples were sieved to <150 μm and delivered to the CheMin X-ray diffraction instrument for quantitative mineralogical analysis. CRISM-derived mineralogy of the Namib Dune and Mount Desert Island and CheMin-derived mineralogy of the Gobabeb and Ogunquit Beach samples can be used in a value-added manner to interpret grain segregation at the bedform to dune-field scale and evaluate contributions from local sediment sources. Models of CRISM data demonstrate that Mount Desert Island is more enriched in olivine and less enriched in plagioclase than Namib dune, suggesting that fine-grained mafic sediments are preferentially mobilized downwind. Curiosity data indicate olivine also forms a coarse lag on the lee sides of barchanoidal dunes. Minor abundances of hematite, quartz, and anhydrite and small differences in the crystal chemistry of plagioclase and pyroxene derived from CheMin data suggest that sediments from the underlying lacustrine rocks also contribute to the Bagnold sands.

Rampe, E. B.↗

NASA NTRS2018

Mineralogy of Aeolian Sand in Gale Crater, Mars

Final Document is attached. Introduction: The Mars Science Laboratory Curi-osity rover landed in Gale crater in August 2012 to search for habitable enironments preserved in the rocks and sediments on the lower slopes of Aeolis Mons (i.e., Mount Sharp). Along the traverse, Curiosity encountered an active aeolian sand sheet, informally known as the Bagnold dune field. Orbital CRISM vis/near-IR data suggest that there are varying abun-dances of olivine and pyroxene across the dune field, where the barchan dunes on the edge of the dune field have stronger olivine signatures than the linear dunes.

Rampe, E. B.↗

NASA NTRS2018

Amorphous Phase Characterization Through X-Ray Diffraction Profile Modeling: Implications for Amorphous Phases in Gale Crater Rocks and Soils

The CheMin X-ray diffraction instrument on the Mars Science Laboratory rover has analyzed 18 rock and soil samples in Gale crater. Diffraction data allow for the identification of major crystalline phases based on the positions and intensities of well-defined peaks and also provides information regarding amorphous and poorly-ordered materials based on the shape and positions of broad scattering humps. The combination of diffraction data, elemental chemistry from APXS (Alpha Particle X-ray Spectrometer) and evolved gas analyses (EGA) from SAM (Sample Analysis at Mars) help constrain possible amorphous materials present in each sample (e.g., glass, opal, iron oxides, sulfates) but are model dependent. We present a novel method to characterize amorphous material in diffraction data and, through this approach, aim to characterize the phases collectively producing the amorphous profiles in CheMin diffraction data. This method may be applied to any diffraction data from samples containing X-ray amorphous materials, not just CheMin datasets, but we re-strict our discussion to Martian-relevant amorphous phases and diffraction data measured by CheMin or CheMin-like instruments.

Achilles, C. N.↗

NASA NTRS2018

Collapsed Smectite in Gale Crater: Martian Clay Minerals May Have Been on Acid

The Mars Science Laboratory (MSL) rover Curiosity began investigating the layered deposits of Gale Crater, Mars, in August 2012. Among the many science instruments on the rover, the CheMin (Chemistry and Mineralogy) X-ray diffractometer (XRD) has been useful in definitively characterizing the mineralogy of samples collected by the rover.

Craig, P. I.↗

NASA NTRS2003

Characterization of Martian Rock Shape for MER Airbag Drop Tests

Using the Viking and Mars Pathfinder landing sites as a guide, this study assessed rock shapes, sizes and burial so they could be compared with rocks on the test platforms. This work allowed comparison of the severity of the rock distributions on the test platforms with the 3 landing sites and helped guide the rocks used on the test platforms during the final airbag qualification tests.

DiMaggio, E. N.↗