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Samuel W Courville

Publications and source records attributed to Samuel W Courville.

4 recordsLinked to original sources
USGS2026

Subsurface water ice mapping on Mars: A probabilistic approach

Subsurface water ice deposits on Mars are an important resource for potential future human exploration. They are also an indicator of the planet’s past climate. However, the distribution of subsurface water ice in Mars’s midlatitudes is uncertain because spacecraft imagery cannot directly observe subsurface ice in most cases. Various spacecraft remote sensing instruments are sensitive to subsurface water ice, including thermal imaging spectrometers, radar sounders, and neutron spectrometers. Geomorphic analyses of images can also implicate subsurface ice. Building upon the data products from the Mars Subsurface Water Ice Mapping project, we provide a probabilistic framework to jointly interpret existing data and estimate the likelihood of subsurface water ice in the Martian midlatitudes between 60 ∘ S and 60 ∘ N with uncertainty. Broadly, we find that near-surface ice is likely present poleward of ∼45 ∘ in both the northern and southern hemispheres. However, closer to the equator, existing remote sensing data cannot uniquely constrain the presence of subsurface water ice. Our probabilistic results provide a framework for quantifying the abundance of ice on Mars, and our uncertainty estimates allow future analysis and exploration to target regions of high uncertainty.

Planetary Science Journal↗
USGS2023

Ice resource mapping on Mars

This chapter explains the rationale for considering shallowly buried (0 to >5 m depth) water ice in the mid-latitudes of Mars as a resource to support future human missions, and describes a NASA-funded effort to map that ice with existing orbital remote-sensing data. In recent decades, numerous studies have used various datasets to investigate the presence and stability of water ice in the Martian shallow subsurface, with the aim of understanding the planet’s recent climate history. As part of a renewed effort to prepare for human Mars missions, NASA has undertaken a more resource-focused approach. Here we describe the Mars Subsurface Water Ice Mapping (SWIM) team’s efforts to characterize the distribution of buried water-ice resources across all longitudes from 60°S to 60°N latitude through the integration of multiple datasets. Deriving composite measures for the presence of accessible ice from a diverse range of remote sensing techniques with unique resolutions and caveats is a challenging problem. To enable data synthesis, the team developed a methodology that assigns values of ice consistency for mapped detections of hydrogen from a neutron spectrometer, thermal behavior from various thermal spectrometers, multiscale geomorphology from imagery and elevation data, and surface and subsurface echoes from a radar sounder. Faced with diverse sensing depths and footprints for these datasets, the team has been pursuing an optimal approach to best represent multi-dataset ice consistency. The current formulation includes the use of weighting factors tuned to depth zones of interest for resource extraction. In the absence of dedicated ground-truth data, the validity of the team’s efforts is assessed by comparing the maps to the locations of fresh, ice-exposing impacts. The highest ice-consistency values occur within discrete zones poleward of ~40° latitude, where ice is relatively shallow, but positive values extend well into the ~20°–30° latitude zone, which is preferable for landing sites due to engineering considerations.

Book chapter↗
USGS2021

Mid-latitude ice on Mars: A science target for planetary climate histories and an exploration target for in situ resources

In the last decade, aided by the high-resolution data and long-term monitoring by NASA’s Mars Reconnaissance Orbiter (MRO) and other spacecraft, extensive evidence has emerged supporting the presence of abundant H2O ground ice throughout much of the mid-latitudes of Mars. Growing evidence indicates that much of this ice is relatively pure, exists within a few meters of the surface, and reaches lower latitudes than previously thought, potentially providing an accessible record of the recent climate and a large in situ resource for future human exploration of Mars. We are reaching the limits of currently available datasets, however, just as we are starting to unlock the climate record and determine the water resources contained within the Martian mid-latitudes. A comprehensive understanding of the nature of this ice would significantly enhance our understanding of Mars’ climate history and total water budget, as well as the effects of orbital/axial forcing on volatiles. In this regard, Mars is a testbed for comparative planetary climate studies, including for exoplanets; these studies are particularly valuable because Mars has many similarities to Earth but lacks the complicating effects of oceans and a biosphere, such that orbital/axial forcing dominates climate variability. Quantifying the volumes, distribution, and properties of the water ice are crucial for addressing two overarching questions in the next decade: 1. What climate record is preserved in mid-latitude ice deposits on Mars? 2. How accessible is the ice as a resource for future exploration? New missions will enable us to capitalize on the major discoveries of the last decade and take the next giant leap in the upcoming decade to address these questions.

Bulletin of the AAS↗