Stephen’s interests include the study of geomorphology, surface processes and planetary geology through field studies, remote sensing, and geospatial analysis understand the Earth, Mars and the Moon. His PhD work focused on the analysis of multispectral and hyperspectral remote sensing data and thermal emission spectroscopy to address geophysical problems in aeolian systems on Earth. He began work in planetary science by mapping the Medusae Fossae Formation on Mars under the direction of Jim Zimbelman at the Smithsonian Institute. He continues work with Dr. David Crown at the Planetary Science Institute on geological mapping projects in volcanic regions of Mars such as Alba Mons, Amphitrites Patera, Tharsis and Elysium, as well as planetary analog work on terrestrial lava flows. 

A significant portion of Stephen’s efforts has been studying terrestrial analog field sites to better understand volcanic and aeolian systems at locations such as Iceland, the western United States, Hawaii, the Canary Islands, and Argentina. These activities inform our understanding of planetary geology in the Solar System. He developed expertise doing low-altitude remote sensing from both commercial and self-built aerial camera systems. This includes cameras mounted on poles, tethered aerosystems (kites!), small unmanned aerial vehicles (sUAS), and specialized near-surface camera rigging to produce digital terrain models (DTMs). This requires stereophotogrammetry software, Global Navigation Satellite System (GNSS) survey equipment, and accurate land surveying. These activities are performed for a number of projects at both NASA Goddard Space Flight Center and PSI.

Game-Changing Development Program: LunaMaps

Stephen’s most recent work has been for Lunar exploration. As we look forward to the Artemis missions, knowledge of surface features such as craters, rock distribution, and other surface characteristics, is key for landing and hazard avoidance during human and robotic space exploration. Missions and technology will benefit from simulations. Through the LuNaMaps project at Goddard Space Flight Center, Stephen is leveraging terrestrial analog field site data to produce realistic and validated high-resolution synthetic topography information for DTMs of the South Polar region of the Moon. See our poster or abstract.

A) Impact crater ejecta (LROC NAC image M126710873R). B) Inset view of ejecta. C) Boulder field on a sand sheet in northern Iceland near the Ask-ja and Holuhraun eruptions. Hillshade of 5 cm/pixel resolution sUAS-generated DEM the same scale.

NASA Goddard Instrument Field Team (GIFT)

New instrument technologies will be integral for robotics and humans to explore planetary surfaces in the solar systems. Field science campaigns allow us to test these technologies and workflows, as well as address fundamental research in geology and astrobiology. I work with sUAS, do field operations and aid science integration, and I’m participating on several projects related to subsurface ice, lava flow emplacement and the migration of aeolian bedforms. Learn more here (PI Jacob Richardson and Bethany Theiling, NASA GSFC).

Fluvial Processes on Alba Mons, Mars

Extensive fluvial dissection occurs on the slopes of Alba Mons, a large shield volcano in the Tharsis province of Mars. In the volcano’s long geological history, it has developed a host of other cross-cutting morphologies from extensive faulting, dust deposition and mid-latitude mantling. As a Co-I, I am using hydrological modeling and morphometric analyses to document variations in geomorphology and constrain the relative timing of fluvial activity among these other geological processes. This is being addressed within a broader geologic mapping investigation (PI David Crown, PSI, MDAP).

Fluvial dissection on the flank of Alba Mons. Colorized MOLA data.

Geology of the Southern Rim of Hellas Basin, Mars

Hellas is the deepest depositional basin on Mars. Numerous processes affected the geology of the southern rim from the Noachian to the Amazonian. The highland patera volcanoes located in the circum-Hellas highlands indicate the major role of early Martian volcanism. This investigation will focuses on using high-resolution imaging and topographic datasets to determine the history of volcanism, tectonism, and degradation. As a Co-I, I will mainly focus on topographic analysis and production of DTMs within a broader geologic mapping investigation (PI David Crown, PSI).

Fluvial channels cross-cut by faults and craters. CTX and colorized MOLA data.

Volcanic Planetary Analogs of Gusev Crater, Mars

Gusev crater is located near the southern highland-northern lowland dichotomy boundary. Its geological history is a complex mix of impact, fluvial, volcanic,
hydrothermal, aeolian and possibly lacustrine processes. A wealth of orbital data and robotic in-situ exploration by the MER Spirit rover have shown us a great deal about martian geology. This project will consist of a broader planetary geologic mapping investigation (PI David Crown, PSI, SSW). As I Co-I, I will co-lead a series of terrestrial field analogue studies utilizing sUAS designed to inform geologic interpretations by investigating small-scale morphologic, topographic, and compositional characteristics of volcanic deposits. See a recent abstract here from Workshop on Terrestrial Analogs for Planetary Exploration.

Apollinaris (top) and Gusev Crater (middle). Colorized MOLA data.

Dust Devils on Earth and Mars

This field study will produce a comprehensive, unbiased suite of measurements to determine how dust devil initiation, physical characteristics, and development reflect the convective and mesoscale atmospheric environment in which they form. We are looking for empirical relationships between Earth dust devil physical characteristics and conditions within the planetary boundary layer at both the micro- and mesoscale at topographically-distinct field sites (PI Lori Fenton, SETI). As a Co-I, I am utilizing an array of high spatial resolution digital cameras to capture the spatial and temporal evolution of dust devils during our team field campaigns. See a recent abstract here.

Remote, In Situ, and Synchrotron Studies for Science and Exploration 2 (RISE2)

The RISE2 team is a NASA’s Solar System Exploration Research Virtual Institute (SSERVI), which brings researchers together to focus on space science and human space exploration (PI Tim Glotch, Stony Brook University). As a Co-I, I’ve lead remote sensing and sUAS operations during field campaigns, which provide high spatial resolution image and DTM data that give context for the field portable instruments used in human space exploration scenarios. See more here from the 2020 NASA Exploration Science Forum.

UAS-generated digital terrain model of Aden Crater summit in the Potrillo Volcanic Field, New Mexico.