Papers by Jeffrey Moersch
Lunar and Planetary Science Conference, Mar 1, 2019
The mineralogy of Gusev crater and Meridiani Planum derived from the Miniature Thermal Emission Spectrometers on the <i>Spirit</i> and <i>Opportunity</i> rovers
Cambridge University Press eBooks, Jun 5, 2008
Thermal Emission Spectrometer hyperspectral analyses of proposed paleolake basins on Mars: No evidence for in-place carbonates
Journal of Geophysical Research, 2005
Several studies have described photogeologic evidence for paleolacustrine basins on Mars, mostly ... more Several studies have described photogeologic evidence for paleolacustrine basins on Mars, mostly within impact craters. If these basins contained persistent standing water in the past, they could still contain deposits of evaporite minerals (e.g., carbonates, sulfates). Many such deposits, if exposed at the surface to a sufficient extent, would be detectable in thermal infrared spectra taken from orbit. Using data from the Mars Global Surveyor Thermal Emission Spectrometer (TES), we have conducted a hyperspectral investigation of 43 putative paleolake basins to search for the spectral signatures of evaporite minerals exposed at a scale comparable to the spatial resolution of a single TES pixel (∼3 × 5 km). Seven basins displaying sufficient surface‐related spectral variation were identified using a principal component analysis on the TES spectral image cube covering the basin and its surroundings and spectral regions of interest (ROIs) were defined. Averaged spectra from ROIs were evaluated using previously developed dust cover index. Those spectra determined to be “dust‐free” were analyzed for composition using linear spectral deconvolution. The same spectra were also analyzed using a spectral ratio and a set of carbonate indices developed in the present work. Most TES spectra in this study were well‐modeled using only previously defined TES spectral end‐members. In addition, the spectral ratios and the carbonate index analyses of these basins indicated that carbonates are not present in abundances greater than the detection limits of these methods. Therefore this study did not find any spectral evidence for evaporite deposits in the basins studied.
Icarus, Jul 1, 2005
The analysis of six landing sites that were candidates for the two NASA Mars Exploration Rovers (... more The analysis of six landing sites that were candidates for the two NASA Mars Exploration Rovers (MER) benefited from recently available image data from the Thermal Emission Imaging Spectrometer (THEMIS) onboard the 2001 Mars Odyssey spacecraft. The combination of daytime and nighttime thermal infrared images from THEMIS supplemented by additional data sets has lead to new or expanded insights into the nature of each landing site. In Meridiani Planum, a layer of lighter-toned, higher thermal inertia material is observable just below the hematite-bearing layer. Gusev Crater displays a more complex stratigraphy than previously observed, including an upper layer with lobate margins. The highest inertia unit of southern Isidis Planitia is confined to topographic lows in the rim/basin margin and does not appear to be due to highland material transported onto the basin floor. The enigmatic, ovoid, blocky terrain on the floor of Melas Chasma displays higher thermal inertia than its surroundings, an indication that it contains coarser or more indurated material than the adjacent aeolian bedforms. The myriad channels of Athabasca Valles display distinctive thermal signatures despite the presence of a bright layer of dust covering the region. The presence of alluvial fans produced from spur-and-gulley erosion of the walls of Eos Chasma demonstrates that mass movements have occurred following the canyon scouring floods.
LPICo, Oct 1, 2008
Introduction: The Mars Express OMEGA and Mars Reconnaissance Orbiter CRISM experiments have disco... more Introduction: The Mars Express OMEGA and Mars Reconnaissance Orbiter CRISM experiments have discovered and mapped mineralogically diverse phyllosilicate deposits on Mars through hyperspectral detection in the near-infrared, e.g., [1], [2], [3], [4], [5]. Examples of these deposits have been reported in the Mawrth Vallis region (~24°N, 340°E), the Nili Fossae region (~22°N, 77°E), a Noachian-aged outcrop in Syrtis Major (~19.5°N, 73°E), and a dark deposit in Ismenius Lacus (~34°N, 17°E) [1], [2], [3], [4], [5]. OMEGA and CRISM spectra of these phyllosilicates are most similar to laboratory spectra of Fe/Mg and Alrich varieties, e.g., [1], [3], [5], [6]. THEMIS, aboard the Mars Odyssey spacecraft, has acquired multispectral thermal infrared images of Mars at 100m/pixel spatial resolution with nearly global coverage. Observation of the primary silicate absorption feature in the thermal infrared may be used to constrain clay mineralogical identification [7]. Although it is recognized that THEMIS may detect spectral uniqueness in clay-rich areas [8], little has been done to utilize this feature, due to the lack of a definitive clay signal deconvolved from corresponding TES data. Here, we have used THEMIS and OMEGA coverage of the Mawrth Vallis, Nili Fossae, Syrtis Major, and Ismenius Lacus to find a clay spectral signature in the thermal infrared. This signature was used to develop a spectral index that is sensitive to the spectral shape of clays. Application of this index to other THEMIS images will be used to identify clay-rich regions in areas of Mars not yet observed by OMEGA or CRISM. Methods: THEMIS daytime infrared images of OMEGA-identified clay-rich regions were corrected for drift, rectified, "deplaided", radiance corrected, and map projected using the THEMIS image processing web interface (). Initially, images with the highest average temperatures (a minimum of 240 K) were chosen to maximize signal-tonoise ratios in the scene. The ENVI 4.2 remote sensing software suite was used to run a custom TES-derived multiplicative atmospheric correction using techniques described in . Mean spectra were extracted from regions of interest (ROIs) corresponding to the locations of OMEGA-identified phyllosilicate-rich deposits. A spectral index was developed based on manual inspection of THEMIS spectral shapes within and outside the phyllosilicate areas mapped by OMEGA. This
An updated global survey of alluvial fans on Mars: Distinguishing alluvial fans from other fan-shaped features through morphologic characterization
Icarus, 2023
Field Observations Using the FIDO Infrared Point Spectrometer: Mineralogical Interpretation and Implications for In Situ Investigations on Mars
AGUFM, Dec 1, 2002
The Field Integrated Design and Operations (FIDO) Rover was deployed for 10 days in August, 2002 ... more The Field Integrated Design and Operations (FIDO) Rover was deployed for 10 days in August, 2002 in a blind field trial that simulated 20 sols of mission operations. This deployment was conducted in support of the Mars Exploration Rover (MER) mission which is scheduled to launch two rovers to Mars in 2003. The FIDO rover is equipped with a mast-mounted
Remotely sensed geology from lander-based to orbital perspectives: Results of FIDO rover May 2000 field tests
Journal of Geophysical Research, Nov 1, 2002
... Plotted spectra are averages as follows: white rocks, sol 6 (3); white rocks, sol 9 (9); Ken&... more ... Plotted spectra are averages as follows: white rocks, sol 6 (3); white rocks, sol 9 (9); Ken's Rock (2). The cause of the feature at ... Citation: Jolliff, B., A. Knoll, RV Morris, J. Moersch, H. McSween, M. Gilmore, R. Arvidson, R. Greeley, K. Herkenhoff, and S. Squyres, Remotely sensed ...
Introduction: A concentration of lobate debris aprons has been previously identified in the easte... more Introduction: A concentration of lobate debris aprons has been previously identified in the eastern Hellas region. These features are lobate masses extending from massif slopes, and are considered to be analagous to terrestrial rock glaciers or protalus lobes [1]. This study focuses on an area of the Reull Vallis region (90-110° E, 30-50° S) that contains 54 identified debris aprons. As a continuation of previous work , infrared images from the Thermal Emission Imaging System (THEMIS) instrument [10] are used to examine spatial variability in surface thermophysical properties of these features. Variations in thermophysical properties are related to physical properties of the apron materials such as composition, density, and particle size. Analysis of THEMIS data, combined with information from other datasets, may provide insights into the formation processes of these features. Background: Located in the southern highlands of Mars, the geologic history of the Reull Vallis region has been discussed in detail by [11]. The debris aprons in this area appear to be some of the youngest features, overlying units of Noachian, Hesperian, and Amazonian ages. Similar to concentric crater fill and lineated valley fill, these aprons are commonly thought to be indicators of near-surface volatiles. Potential analogs for apron emplacement include rock glaciers, debris covered glaciers, and mass movements of ice rich material [1-3,7,8,12-13], although it likely that multiple mechanisms are responsible for apron formation. Apron surface expressions should be a record of formation and later modification by volatile loss [e.g. 12]. A preliminary examination of the debris aprons in this area using THEMIS data showed variations in nighttime temperature of these features . At the time this study was undertaken, however, the study region did not have complete THEMIS nighttime IR coverage, and less than half of the 54 aprons identified by were studied. In addition, no daytime images were analyzed. Since then, THEMIS has imaged nearly 100% of this area during the night, as well as acquiring more daytime images. The ability to analyze additional data allows for expansion of the previous work. Image Analysis: THEMIS infrared images, taken both during daytime and nightime, were identified for the defined study area using JMars [14]. Initial image processing is undertaken via the THMPROC web page interface [15], using the undrift/dewobble, rectify, deplaid, and unrectify options. These processing steps should calibrate the images and remove a significant portion of systematic instrument-induced variations. At
Remote Sensing of Terrestrial Analogs for Evaporite Basins on Mars: Analysis of Groundtruth
The presence or absence of evaporite basins on Mars has important implications for the role that ... more The presence or absence of evaporite basins on Mars has important implications for the role that liquid water has played in shaping the planet's climatic history. Orbital investigations of surface mineralogy are crucial to this exploration effort. With the exception of a few specular hematite sites, the Thermal Emission Spectrometer (TES) now orbiting Mars has yet to find significant mineralogical
Remote Sensing of the Haughton Impact Structure (HIS): A Terrestrial Proof of Concept for Using the Remote Sensing of Martian Craters as a Probe of Subsurface Composition
ABSTRACT
Valles Marineris Dune Fields as seen from the HiRISE, CTX and THEMIS cameras
ABSTRACT Dune fields on Mars offer an opportunity to investigate the nature of eroded sediments a... more ABSTRACT Dune fields on Mars offer an opportunity to investigate the nature of eroded sediments and their interactions with the atmosphere. We examined 20 dune fields in Valles Marineris (VM) from the Mars Global Digital Dune Database [Hayward et al., 2007] to identify significant trends in composition, thermophysical properties, morphology and origin. Dune fields were examined in terms of: slopes, albedo, dust index, thermal inertia and the corresponding derived particle size. We have used image data from the Mars Reconnaissance Orbiter (MRO) instruments CTX [McEwen et al., 2006] and HiRISE [Malin et al., 2007] to establish geologic context for the dune fields, and in particular, to examine their relationships to neighboring geologic units. In general, VM dune fields display greater topographic relief and closer proximity to their inferred source regions than is typical for dune fields elsewhere on Mars. These dunes have a relatively high TES-derived thermal inertia mean value (394 Jm-2K-1 s-1/2, units hereafter assumed), which corresponds to ~1000 mum grains [Pelkey et al., 2001] or very coarse sand sizes. In contrast, typical non-VM dunes have a lower thermal inertia value of ~250, corresponding to ~350 mum grains. To investigate this more closely, high-resolution THEMIS-derived thermal inertia maps were created [Putzig et al., 2004]. CTX and HiRISE visible images revealed that bedrock outcrops are commonly found within dune fields, erroneously elevating the TES thermal inertia values over the ~3x5-km TES footprint. However, even after excluding intra-dune outcrop areas using higher-resolution THEMIS data, several VM dune fields have anomalously high thermal inertia values (&gt;500) compared with non-VM dune fields. It is possible that the high thermal inertia values are indicative of indurated (fossilized) dune surfaces, rather than large individual grain sizes. Coprates Chasma contains a concentration of 6 dune fields both within the main chasm and in depressions to the south. The southern fields are comprised of isolated barchanoid dunes, in close proximity to or atop wall material that has been deposited by mass wasting. In the main chasm, previously unidentified barchans composed of large grain sizes, as inferred from THEMIS thermal inertia, are found in CTX images within spur and gully wall units 2-3 km above the canyon floor. TES spectrum of these dunes indicates a basaltic composition, suggesting that the nearby wall units, also thought to be of a basaltic composition [McEwen et al., 1999], could be the source of the dune sediments. Future MRO observations of this area may resolve whether these dune sediments are locally derived. Ganges Chasma has the highest concentration of dunes in VM, including the largest (~6000 km2) non-polar dune field on Mars. These dunes are found surrounding the sulfate-bearing Ganges Mensa and other layered deposits. In one example, a light-toned yardang containing CRISM-detected hydrated sulfates [Pelkey et al., 2007] has shed fans of fine-grained material, contributing sediment to the area. Dune slipface orientation would suggest a dominant wind direction blowing to the west at the last time of dunes activity. This corresponds with the more recent deposit of lighter-toned material down-wind and atop the dark-toned sand sheets, as observed in HiRISE and THEMIS thermal inertia images. These lighter-toned materials, inferred to be composed of sulfate grains (~350 mum), form bright ripples which gradually disappear away from the yardang. Whether these sulfates constitute a significant percentage of the dune composition is currently under investigation.
Introduction: Dune fields on Mars offer an opportunity to investigate the nature of eroded sedime... more Introduction: Dune fields on Mars offer an opportunity to investigate the nature of eroded sediments and their interactions with the atmosphere. We examined and re-mapped 20 dune fields in Valles Marineris (VM) originally mapped by the Mars Global Digital Dune Database (MGD 3 ) [1] to identify significant trends in composition, thermophysical properties, morphology and origin. In addition, five new dune fields were identified, doubling the total VM dune area to ~16,000 km 2 . Valles Marineris has large topographic relief (~10 km), relatively high atmospheric pressure (>8 mb), and multiple geologic units as potential sediment sources. Dune grain sizes and inferred provenance will be compared with previous studies of other Martian dune fields to further understand the global context and processes of the VM environment. If dunes are determined to be locally derived this will provide insight into the regional composition of VM. Motivation: Despite three decades of study [2-4], questions remain regarding the composition, age, morphology and sediment supply (present and past) for Martian dunes. The dune fields in VM show a large range of dune morphologies, thermophysical properties and potential sand sources. The rift system exposes a ~10-km-thick section of Martian stratigraphy from which dune material may be derived. The driving questions for this study are: What are typical grain sizes? Is the sediment derived locally or trapped from outside VM? Are VM dunes similar to typical midlatitude crater-derived dunes outside VM? Method: Twenty-five VM dune fields were mapped and characterized using 25 different parameters, including: MOLA elevation, slopes, TES albedo, DCI, TES [5] and THEMIS thermal inertia [6]. Particle sizes were derived from TES and THEMIS thermal inertia measurements using the method described in ; however only values ≤350 Jm -2 K -1 s -1/2 were considered. Geologic context for the dune fields were acquired with visible image data from the Mars Reconnaissance Orbiter (MRO) instruments CTX and HiRISE. Our remapping effort used co-registered THEMIS thermal inertia and CTX visible images to ensure dune field boundaries excluded bedrock and rubble that could spuriously elevate thermophysical measurements. Visible trends were sought for regions, dune morphology, elevation and composition. Results: In general, VM dune fields display greater topographic relief and closer proximity to their inferred source regions than is typical for mid-latitude dune
Journal of Geophysical Research: Planets, 2014
The presence of hydrated phases in the soil and near-surface bedrock of Gale Crater is thought to... more The presence of hydrated phases in the soil and near-surface bedrock of Gale Crater is thought to be direct evidence for water-rock interaction in the crater in the ancient past. Layered sediments over the Gale Crater floor are thought to have formed in past epochs due to sediment transport, accumulation, and cementation through interaction with fluids, and the observed strata of water-bearing minerals record the history of these episodes. The first data analysis of the Dynamic Albedo of Neutrons (DAN) investigation on board the Curiosity rover is presented for 154 individual points of active mode measurements along 1900 m of the traverse over the first 361 Martian solar days in Gale crater. It is found that a model of constant water content within subsurface should be rejected for practically all tested points, whereas a two-layer model with different water contents in each layer is supported by the data. A so-called direct two-layer model (water content increasing with depth) yields acceptable fits for odometry ranges between 0 and 455 m and beyond 638 m. The mean water (H 2 O) abundances of the top and bottom layers vary from 1.5 to 1.7 wt % and from 2.2 to 3.3 wt %, respectively, while at some tested spots the water content is estimated to be as high as ~5 wt %. The data for odometry range 455-638 m support an inverse two-layer model (water content decreasing with depth), with an estimated mean water abundance of 2.1 ± 0.1 wt % and 1.4 ± 0.04 wt % in the top and bottom layers, respectively. DAN (Dynamic Albedo of Neutrons) is a Russian-contributed instrument on MSL [see that addresses the need for these measurements. It uses a method of active neutron sensing of the shallow subsurface. DAN has a pulsing neutron generator (PNG) that produces 2 μs pulses of 14.1 MeV neutrons at a frequency of 10 Hz, with about 10 7 particles in each pulse. The high-energy neutrons penetrate into the subsurface and follow a random walk through interactions with soil and bedrock nuclei, changing direction and decreasing in energy at each interaction (i.e., the diffusion of neutrons takes place in MITROFANOV ET AL.
Icarus, 2015
A CTX northward prospective view of the Endeavour crater, showing two dune fields and the locatio... more A CTX northward prospective view of the Endeavour crater, showing two dune fields and the location of the Opportunity rover (gold star) during the investigation.
Science, 2013
The ChemCam instrument, which provides insight into martian soil chemistry at the submillimeter s... more The ChemCam instrument, which provides insight into martian soil chemistry at the submillimeter scale, identified two principal soil types along the Curiosity rover traverse: a fine-grained mafic type and a locally derived, coarse-grained felsic type. The mafic soil component is representative of widespread martian soils and is similar in composition to the martian dust. It possesses a ubiquitous hydrogen signature in ChemCam spectra, corresponding to the hydration of the amorphous phases found in the soil by the CheMin instrument. This hydration likely accounts for an important fraction of the global hydration of the surface seen by previous orbital measurements. ChemCam analyses did not reveal any significant exchange of water vapor between the regolith and the atmosphere. These observations provide constraints on the nature of the amorphous phases and their hydration.
Science, 2003
The Thermal Emission Imaging System (THEMIS) on Mars Odyssey has produced infrared to visible wav... more The Thermal Emission Imaging System (THEMIS) on Mars Odyssey has produced infrared to visible wavelength images of the martian surface that show lithologically distinct layers with variable thickness, implying temporal changes in the processes or environments during or after their formation. Kilometer-scale exposures of bedrockare observed; elsewhere airfall dust completely mantles the surface over thousands of square kilometers. Mars has compositional variations at 100-meter scales, for example, an exposure of olivine-rich basalt in the walls of Ganges Chasma. Thermally distinct ejecta facies occur around some craters with variations associated with crater age. Polar observations have identified temporal patches of water frost in the north polar cap. No thermal signatures associated with endogenic heat sources have been identified.
Special considerations in lander and rover-based thermal emission spectroscopy of geologic surfaces
Current plans for future Mars missions include small lander- and rover-borne thermal infrared spe... more Current plans for future Mars missions include small lander- and rover-borne thermal infrared spectrometers for use in exploring the surface. While the utility of infrared spectrometers in determining the composition of geologic surfaces from airborne and spaceborne platforms has been amply demonstrated, little experience exists in using functionally similar instruments on the ground in the context of planetary science. What work has been done on this problem has mostly utilized field spectrometers that look down on geologic surfaces, not horizontally, as the spectrometers on the Mars Surveyor '01 lander and '03 and '05 rovers often will. There are important differences between downward-looking and horizontal-looking thermal emission spectra related to the very different radiative environment seen by targets with non-horizontal orientations. These effects include: the reflection of upward-welling radiance from the ground as a function of the orientation of target rock...
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Papers by Jeffrey Moersch