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DN-008 L: Geotechnical properties of highland regolith at the lunar south pole

How South Pole regolith behaves mechanically: particle sizes down to under 10 μm, shape, density, porosity, bearing capacity and cohesion, to at least 1 m depth (up to about 3 m for the fine fraction), across several sites and slopes. Today's design values come from Apollo samples and orbital estimates, and no samples have been returned from the South Pole. The data feeds landing, plume-surface interaction and trafficability analyses. It is named in the Moon Base Users Guide (near-term), under five challenges, more than any other data gap except DN-009 L and DN-019 L (Data gaps spreadsheet, DN-008 L; Users Guide, pp. 12–13).

Quotations below are from row DN-008 L of the data gaps spreadsheet unless marked otherwise. ADD Rev C's Appendix E prints the same record as a table, and it matches the row field for field (ADD Rev C, p. 272).

Description

"Characterize lunar regolith physical and mechanical properties as a function of depth (min depth extent: 1 meter), area, and terrain slope/features, to understand South Pole properties and their variability. These measurements should be taken over multiple locations at the lunar south pole at locations representative of landing and exploration sites."

Data utility (white paper, Table Two): "To enable higher certainty in the landing environment to inform lander design and site selection" (ACR25 data-gaps white paper, p. 3).

Need driver and data type

  • Need driver: Lunar Surface Natural Environment Characterization
  • Data type: In Situ Measurement/Sample Return

Target measurement parameters

"Particle size distribution (<10μm), particle morphology and density, other geotechnical properties including but not limited to porosity, permeability, bulk density, bearing capacity, cohesion. "Fine fraction" of particle size distribution (particles < ~50 microns), variation with depth up to ~3 m."

Current state of data

"Geotechnical property values in M2M Design Specification for Natural Environments (DSNE) rely on historical archive of Apollo results and estimates from analyses of orbital imagery or modelling. Variance in these values spatially, with terrain type, and with depth is not well constrained."

Impact if data is unavailable

"Limitations in in-situ regolith sampling and characterization increase uncertainty to, analyses for interactions between footpads and regolith, rocket engine blast effects (erosion and ejection of material), etc. Limited datasets of lunar samples result in uncertainty about the stability and behavior of the lunar surface. This is particularly true for the South Pole, as no samples from this region have been returned and properties may differ from previous equatorial mission sites (i.e., particle size, porosity). Insufficient characterization of regolith geotechnical properties can potentially lead to instability of spacecraft on the lunar surface and lack of soil integrity."

Benefits if data is available

"Increased confidence/decreased uncertainty in landing, plume-surface interaction, and trafficability analyses, which may increase flexibility/allow more areas and terrain to be considered for mission operations. For example, better constraints on slope stability could arise from regolith strength measurements. Data can be used to predict structural behavior of lunar vehicles and structures as the architecture evolves. The geotechnical stability of landing vehicles can be better estimated/calculated, which will inform assessments regarding the structural integrity and capacity of lunar regolith when vehicles have landed on the lunar surface."

Traceability

Priority

None. The spreadsheet has no priority field, and the Users Guide calls the data-gap list "not comprehensive or prioritized" (Users Guide, p. 11).

Moon Base relevance

The Users Guide names DN-008 L for five challenges (Users Guide, pp. 12–13):

  • "Operating on the Lunar Surface for Long Durations" (headline challenge, p. 12). Its knowledge challenge has two sentences: "Characterize the lunar surface environment to predict performance impacts and risks associated with long duration surface operations." and "Investigate dust mechanics, regolith geotechnical properties, and radiation/charged particle fluctuations, seasonal patterns, and scattering." The guide lists DN-008 L to DN-013 L, DN-015 L, DN-016 L and DN-019 L under both sentences together and does not say which sentence each serves. The challenge's technology half cites tech gaps #0101, #0201, #0301, #0801 and #0804.
  • "Securing sites" (p. 12): "Identifying, selecting, and landing at individual sites requires more data about the lunar surface, including regolith properties, high-resolution imagery, mapping, and resource locations." Also cited: DN-001 L to DN-007 L, DN-009 L, DN-010 L, DN-013 L and DN-014 L. No tech gap.
  • "Manipulating regolith" (p. 13): "Manipulating lunar regolith at scale for excavation, compaction, and site preparation requires in depth understanding of regolith properties and large scale excavation and construction." Also cited: data gaps DN-009 L, DN-010 L and DN-019 L; tech gaps #0505 and #0605.
  • "Electrical connections" (p. 13): "Connecting systems and sharing power on the lunar surface requires dust tolerant connections and the ability to deploy cables." Also cited: data gaps DN-009 L and DN-019 L; tech gap #0903.
  • "Pressurized mating" (p. 13): "Mating pressurized systems on the lunar surface requires dust tolerant systems, which rely on detailed knowledge of lunar regolith and the surface environment." Also cited: data gaps DN-009 L, DN-010 L and DN-019 L; tech gap #0807.

The guide ties its challenges to "near-term Moon Base development efforts": missions in phase one "offer opportunities to collect data and mature technologies to enable essential phase two and phase three capabilities" (p. 11). See Technology and knowledge challenges.

A Moon Base payload with no phase, same subject (the wiki's link): DISCO, selected through PRISM in September 2026, will study "how the lunar surface behaves, from how rocket exhaust disturbs the ground to how stable it is for mobility". The release names no geotechnical property (PRISM release, "DISCO").

Sources

Data gaps spreadsheet, DN-008 L · ACR25 data-gaps white paper, p. 3 · Users Guide, pp. 11–13 · 2025 Architecture Update, p. 14 · ADD Rev C, pp. 202, 272