PSI releases new global maps of Martian subsurface water ice
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Planetary Science Institute researchers release new global maps of Martian subsurface water ice, leveraging thermal data from NASA’s Mars Global Surveyor and Mars Reconnaissance Orbiter. The maps identify ice within a meter of the surface, a resource that could be converted into hydrazine rocket fuel for human missions. The team's cross-map comparison reveals discrepancies from instrument sensitivity and atmospheric dust.
Thermal Ice Detection
The SWIM team used thermal emission data from the Mars Global Surveyor’s TES and the Mars Reconnaissance Orbiter’s MCS to map temperature changes over day-night cycles. Regions with buried ice warm and cool differently than homogeneous soil, revealing depth to ice. The technique builds on earlier mapping but integrates updated atmospheric correction, reducing false positives in dusty equatorial zones. Earlier missions, such as NASA’s Phoenix lander, confirmed ice at high latitudes, but the new maps extend coverage to mid-latitudes where solar-powered equipment is viable.
Map Discrepancies
Sizemore’s paper in The Planetary Science Journal compares the SWIM maps with two other leading maps, derived using alternative numerical models from the same orbital datasets. The maps agree on broad ice distributions but diverge in specific regions, particularly where atmospheric dust interferes with thermal modeling. Differences in instrument sensitivity and seasonal dust variability account for up to 30% discrepancy in burial depth estimates in some areas. These comparisons highlight the need for ground-truth measurements.
In-Situ Fuel Production
Water ice excavated from the subsurface can be split into hydrogen and oxygen and converted into hydrazine, a rocket propellant. This process, known as in-situ resource utilization (ISRU), could cut mission mass by 60%, according to NASA concepts. Astronauts would dig or drill to access ice, making precise depth maps mission-critical. The new maps mark a step toward NASA’s goal of a sustained human presence on Mars.
What's Next
The SWIM team plans to incorporate data from the upcoming Mars Ice Mapper mission, while laboratory tests of ice-excavation tools are ongoing. It remains uncertain whether ice in mid-latitudes is sufficiently pure and accessible to support a human mission within the next decade.
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PSI releases new global maps of Martian subsurface water ice
