Stephen Paul Scheidt

Planetary Science Institute · Department of Planetary Sciences

We present initial results of an investigation into meteorological and geological controls on the formation of dust devils (i.e., dust-filled vortices formed in the daytime dry convective boundary layer). During a 2-week field campaign in June 2019 at Smith Creek Valley (SCV), Nevada, USA, we conducted automated time-lapse stereo imaging of dust de...

We examine the morphology and chemistry of the Vikrahraun basaltic eruption emplaced at Askja Volcano, Iceland, from Oct. 26–Dec. 17, 1961. The eruption had three eruptive events, initiating with aʻa and followed by alternating aʻa and pahoehoe lava flow emplacement. We determine that while the eruption is chemically homogenous (Fe/Mg = 1.9–2.2, 47...

Surface roughness is a commonly used parameter for the quantitative analysis and characterization of geological terrains on Earth, as well as on other planetary bodies, particularly where detailed optical data may not be available. Here, we statistically investigate if surface roughness can be used to distinguish between different lava facies in re...

The 2014–2015 CE rift event associated with the Bárðarbunga eruption at Holuhraun, Iceland, offers a unique opportunity to study the spatial and temporal evolution of a rift graben. We present the first four-dimensional (three-dimensional plus time) monitoring of the formation and evolution of a graben during active magma transport using a suite of...

The 2014–2015 Holuhraun eruption extruded >1 km³ of lava in a barren region of the Icelandic highlands. Due to its large volume and the abundance of data for this eruption, Holuhraun is an ideal site to investigate fissure-fed eruption products for comparison with other large lava flows-fields on Earth and other planetary bodies. To characterize la...

Premise: TagSeq is a cost-effective approach for gene expression studies requiring a large number of samples. To date, TagSeq studies in plants have been limited to those with a high-quality reference genome. We tested the suitability of reference transcriptomes for TagSeq in non-model plants, as part of a study of natural gene expression variatio...

Basaltic lava flows are common on the surface of the Earth and other terrestrial bodies. However, inflation—including a combination of initially rapid molten core thickening and gradual crustal growth—must be accounted for to enable accurate reconstructions of eruption parameters from observed lava flow morphologies. The shape of an inflated lava f...

Premise of the study TagSeq is a cost-effective approach for gene expression studies requiring a large number of samples. To date, TagSeq studies in plants have been limited to those with a high quality reference genome. We tested the suitability of reference transcriptomes for TagSeq in non-model plants, as part of a study of natural gene expressi...

Field portable instrumentation, such as in situ geochemical analyzers or broader field of view instruments like multispectral imagers or other imaging capabilities, has the potential to dramatically increase the science return of a planetary surface exploration mission. However, more work is needed to determine how emerging portable technologies sh...

Hrad Vallis is an Amazonian-age outflow channel located in the northwestern part of the Elysium Volcanic Province of Mars. The formation of Hrad Vallis may have been associated with catastrophic aqueous floods and volcanism, which makes determining its emplacement history important for constraining the planet's hydrological and thermal evolution du...

The large volume of high-resolution images acquired by the Mars Reconnaissance Orbiter has opened a new frontier for developing automated approaches to detecting landforms on the surface of Mars. However, most landform classifiers focus on crater detection, which represents only one of many geological landforms of scientific interest. In this work,...

We map the cross-cutting relationships between faults, valley networks, and (volcanic) flows on Alba Mons to infer the temporal sequences of the major processes that influenced the area. Preliminary mapping on the northwestern flank suggests that lava flows predate the valley networks, and the faults postdate both the flows and the fluvial valleys....

Aerodynamic roughness heights of 1–3 cm were obtained from measured wind profiles collected among fields of gravel-mantled megaripples in the high desert of the Puna region of northwestern Argentina. Roughness height appears to be relatively insensitive to the angle at which the wind was incident upon the bedforms throughout the study sites. The re...

Equipment for performing low-altitude aerial photography for geomorphological studies on 10–1000 m scales is described, with particular reference to study of sand dunes. An automatic digital camera is lofted by a parafoil kite: the arrangement costs around $400, collapses into a volume of ∼2 l and can be deployed in a few minutes, making it conveni...

The fracture patterns of lava flows exhibit unique structure associated with emplacement, shown here from high-resolution 3D models generated from field photos.

Wind-profile measurements indicate aerodynamic roughness heights of 1 to 3 cm for fields of gravel-coated megaripples that are up to 1 m in height.

We summarize recent work applying multiview stereo photogrammetry to create 3D digital models of dunes, ripples, and TARs for the purpose of Mars analog studies.

Ten high precision topographic profiles across a reversing dune were created from a differential global position system (DGPS). The shapes of the profiles reveal a progression from immature to transitional to mature characteristics moving up the dune. When scaled by the basal width along each profile, shape characteristics can be compared for profi...

The Coregistration of Optically Sensed Images and Correlation (COSI-Corr) algorithm was used to estimate dune migration and sand flux rates from a series of remotely-sensed optical image pairs. Several areas of barchan and transverse dunes transport sand along definite pathways, feeding the southern part of the Namib Sand Sea from beaches and defla...

The Medusae Fossae Formation (MFF) on Mars is an intensely eroded deposit north of the cratered highlands. It is widely thought that MFF materials were emplaced through ignimbrite eruptions. Recent geologic mapping of western MFF identified outliers of MFF materials well beyond the previously mapped western extent for the deposit, including outlier...

Impact craters were counted on the THEMIS IR base map for MFF map units. Results suggest that units from both the lower and middle members of MFF were emplaced during the Hesperian rather than the Amazonian.

Soil moisture studies, especially those in semi-arid environments, are critical in understanding weather, climate, agricultural productivity, society impact, and national security. However, studying this type of environment is often difficult and costly due to remote locations, rapid dry-down following precipitation events, and required specialized...

The Gran Desierto dune field is only partially composed of quartz-rich sands from the ancestral Colorado River. Local sources have been previously underestimated as a major source of sand because previous remote-sensing studies were limited in their capability to detect silicate minerals. Compositions of sands were evaluated in this study using a c...

Gravel megaripples in the Puna of Argentina are the coarsest yet to be described on Earth. They may be the best terrestrial analogs for martian granule ripples. We present preliminary sedimentological and morphological data and observations.

Samples of gravel, sand and bedrock were collected from a terrestrial analog site for Mars granule ripples in the Puna Desert. Analysis was undertaken using remote-sensing and spectroscopy.

This abstract describes the preliminary mapping results of the MC-16 NW quadrangle of Mars, where a large portion of the area is a Medusae Fossae Formation (MFF). We look more in depth at the subdivisions of the MFF units.

Prior to mineral dust deposition affecting albedo, aerosols can have direct and indirect effects on local to regional scale climate by changing both the shortwave and longwave radiative forcing. In addition, mineral dust causes health hazards, such as respiratory-related illnesses and deaths, loss of agricultural soil, and safety hazards to aviatio...

Depositional and erosional landforms were examined within enclosed basins in Nevada and central Oregon in order to assess the detectability of possible pluvial features within crater lakes on Mars. A Trimble R8 Differential Global Positioning System (DGPS) was used to survey both shoreline sequences and erosional scarps (at the highstand level), al...

1] Determinations of soil moisture and sediment availability in arid regions are important indicators of local climate variability and the potential for future dust storm events. Data from the Advanced Spaceborne Thermal Emission and Reflection (ASTER) radiometer were used to derive the relationships among potential soil erosion, soil moisture, and...

Measurements of rates of dune migration and sand flux are important to understanding the dynamics of aeolian systems, including sand encroachment, desertification, and response to changes in climate. The recent development of the Coregistration of Optically Sensed Images and Correlation (COSI-Corr) algorithm allows a unique remote-sensing approach...

Soon after its launch in December 1999, the ASTER sensor on the NASA Terra satellite began acquiring infrared data of dynamic surface processes around the world. For the first time in history, well calibrated, relatively high spatial resolution thermal infrared (TIR) data was being collected in more than two spectral bands. These data began a new e...

Thermal infrared (TIR) remote-sensing and field-based observations were used to study aeolian systems, specifically sand transport pathways, dust emission sources and Saharan atmospheric dust. A method was developed for generating seamless and radiometrically accurate mosaics of thermal infrared data from the Advanced Spaceborne Thermal Emission an...

Climate variability and rapid urbanization have influenced the sand environments in the northern Coachella Valley throughout the late 20th century. This paper addresses changes in the spatial relationships among different sand deposits at northern Coachella Valley between two recent time periods by using satellite data acquired from the Advanced Sp...

Data from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) have a significant advantage over previous datasets because of the combination of high spatial resolution (15–90 m) and enhanced multispectral capabilities, particularly in the thermal infrared (TIR) atmospheric window (8–12 μm) of the Earth where common silicate m...

The identification and characterization of major mineral dust source areas from the Sahara Desert and the composition of these particulates are critical to our understanding of global dust production, models of atmospheric emission and transport, and determination of radiative properties of dust plumes from desert regions. The locations of many of...

Discussed data fusion of ASTER visible and near infrared (VNIR), shortwave infrared (SWIR) and thermal infrared (TIR) measurements to aid classification of desert coastal ecosystems and the 2002-2003 assessment of damage from the 1991 oil spill in the Persian Gulf.

Reported on the research to study the composition of potential dust sources in the Sahara Desert using ASTER thermal infrared (TIR) satellite and spectroscopy data.