Provisional Geotechnical Excavation and Tunneling Zoning for Lunar Construction

A Preliminary Terrain-Based Framework for Contractors, Engineers, and Mission Planners Working on Lunar Surface Infrastructure

Executive Summary

Lunar surface excavation will play a critical role in enabling permanent infrastructure for energy, habitation, shielding, and in-situ resource utilization. However, unlike terrestrial sites, the Moon presents extreme geological variability, highly compacted regolith layers, and localized hazards that remain poorly integrated into most construction concepts.

This guide introduces a zoning framework for lunar excavation based on five excavation classes (L1 to L5) and links them to terrain types, regolith thickness, and geotechnical risk. Drawing from validated datasets, Apollo, Chang’e, LRO, and grounded in established geomechanical methodologies (Bieniawski, Hoek–Brown, Q-System), this approach defines practical excavation depths and tool feasibility by location.

The goal is to enable contractors and mission planners to make terrain-informed decisions on excavation scope, tool class selection, and site prioritization. It also outlines where tunneling, vault construction, or subsurface deployments may be technically feasible, and where they are not. All recommendations are provisional but conservative, reflecting the most reliable regolith and geological data available as of 2025.

1. Why Excavation Zoning Matters on the Moon

Lunar surface excavation is not uniform. It cannot be approached with a single method or tool class across all sites. The Moon presents stratigraphic and mechanical variability that, if not properly accounted for, will result in operational failure, equipment loss, and unacceptable construction delays. A zoning-based excavation framework, similar to terrestrial classifications used in civil and mining engineering, is necessary to enable reliable, terrain-informed planning and execution.

On Earth, engineered excavations are classified by material behavior, geometry, and risk class. Rock mass characterization systems such as Bieniawski’s RMR¹, the Hoek–Brown criterion², and the Q-system³ are used routinely to prescribe excavation method, support type, and tool requirements. These systems are rooted in empirical performance across thousands of kilometers of underground works. They enable engineers to assign practical excavation classes based on limited but essential field data. Lunar surface operations, while uniquely constrained by vacuum, low gravity, and dust, must follow the same logic if mission success is to be achieved at scale.

The regolith is not a homogeneous layer. Apollo trenching, penetrometer testing, and returned core tubes revealed rapid variation in particle size, cohesion, and penetration resistance across shallow depths⁴. Apollo 16, located in the Descartes highlands, recorded regolith depths exceeding 12 meters, interspersed with high-density rock fragments and block layers. In contrast, the mare basalts at the Apollo 11 and 12 sites presented relatively thin regolith profiles of 2 to 4 meters, with higher dust mobilization and greater lateral uniformity. More recent radar-based measurements from Chang’e 5 and 6 confirm this dichotomy, showing mare regolith thicknesses between 1.5 and 8 meters⁵, with distinct internal reflectors indicating depositional layers and embedded rock lenses. These variations are not academic; they directly impact cut depth, trench slope, tool wear, and excavation strategy.

Furthermore, specific terrain types, ejecta blankets, crater rims, and basaltic flows, present additional constraints. Crater rim zones, for instance, exhibit low regolith coverage and large block content due to ballistic emplacement. These areas are mechanically unstable and unsuitable for deep cuts or anchoring. In contrast, mature highland regions offer thick regolith suitable for both trenching and subsurface structures, provided proper equipment is used and slope control is planned. Without a zoning typology, contractors risk overestimating excavation depth capacity or selecting equipment incompatible with the site’s ground behavior.

This proposed L1–L5 excavation zoning system defines excavation depth classes about tool feasibility, terrain type, and known geotechnical constraints. It integrates available Apollo and Chang’e datasets with Earth-based excavation logic to establish a clear framework for planning and execution. This is not a predictive model; it is a planning tool, grounded in data and adapted for engineering applications. Each zone, L1 through L5, is linked to realistic regolith depths, tool classes, and terrain types, enabling clear contractor guidance. The objective is to move from generalized assumptions to location-specific excavation planning, as is standard in all mature infrastructure engineering. Table 1 shows the proposed Lunar Excavation Zoning (LEZ).

2. Excavation Zoning Framework (L1–L5)

Lunar excavation activities must be categorized according to operational scope, terrain condition, and geotechnical feasibility. This zoning framework defines five excavation classes, L1 through L5, designed to standardize planning across different depths and tool requirements. Each zone corresponds to a range of excavation depth and is linked to expected terrain suitability, tool class, and specific engineering applications.

This zoning approach is adapted from terrestrial classification methods, where excavation class is a function of geometry, ground behavior, and structural demands. On the Moon, additional constraints, such as regolith stratification, boulder frequency, vacuum dust behavior, and low gravity, require tailored definitions.

The purpose of this zoning system is to allow mission planners and contractors to make clear decisions about tooling, slope design, and expected excavation limits based on regolith depth and terrain context. This system does not assume homogeneity. Each class is subject to terrain validation and localized ground data acquisition.

Table 1 – Lunar Excavation Zoning Framework (L1–L5)

Zoning Class	Excavation Depth	Typical Application	Terrain Suitability	Tool Class	Considerations
L1	0-0.3 m	Surface clearance, micro-trenching, instrumentation	All terrains except crater rims	Clearing blade, brush, regolith blower	Minimal load bearing, loose fines, surface dust
L2	0.3-1.5 m	Cabling, shallow ISRU piping, and small foundation slabs	Mare, highlands, transitional zones	Backhoe, light trenchers	Shear strength, cohesion, and boulder avoidance
L3	1.5-3 m	Deep trenches, storage pits, and utility corridors	Highlands, mare basins	Heavy trenchers, rotary diggers	Slope angle, excavation support design
L4	3-5 m	Structural cuts, berm foundations, buried ISRU units	Highlands, transitional with slope control	Excavators with slope stability support	Bench width, regolith stability, block interference
L5	>5m	Subsurface vaulting, pressurized tunnels, and anchoring	Highlands, megaregolith zones, lava tubes	Penetrators, TBM, headroader, raiseboring, etc.	Ground control modeling; structural roof integrity

📌 Note: The excavation zoning classes presented in Table 1 are provisional and intended as a preliminary engineering framework to support mission planning, equipment selection, and site feasibility assessment. All depth ranges and tool recommendations are based on currently available regolith data from Apollo, Chang’e, and LRO datasets, combined with terrestrial excavation principles. Local geological validation, including radar, penetrometer, and core sampling, remains essential before deployment. This classification does not substitute for site-specific geotechnical investigation.

3. Terrain Types and Regolith Depth Ranges

Lunar surface excavation depends directly on terrain classification and regolith thickness. Regolith is the product of billions of years of meteoritic bombardment, thermal cycling, and solar wind interaction. It is not a uniform layer but a stratified, location-specific deposit with significant geotechnical implications. For engineering purposes, the excavation potential of any lunar site begins with understanding the terrain type and estimating the regolith profile based on the most reliable orbital and in-situ data.

The major terrain classes that define excavation feasibility are:

• Mare Plains: These are basaltic volcanic regions with relatively low topography. Regolith here is typically finer, compacted, and thinner than in the highlands. Estimates range from 2 to 8 meters based on Apollo core samples and Chang’e radar soundings⁶.

• Highlands: Anorthositic crustal terrains with older surfaces and thicker regolith. Depths often exceed 10 meters, with high block content and a mature soil profile. Apollo 16 recorded regolith depths greater than 12 meters in the Descartes region⁴.

• South Pole–Aitken Basin (SPA) and Farside Regions: These are structurally complex terrains with local variability. Regolith thickness can be shallow in places, with fractured megaregolith or breccia directly beneath the surface. These regions require local radar or seismic validation before excavation planning⁵.

• Transitional Zones: Located between the mare and the highland regions, these areas show mixed stratigraphy and slope. Regolith depth and composition are highly variable, demanding site-specific assessment.

• Crater Rims and Ejecta Deposits: These zones feature low regolith coverage, high block density, and unstable surface conditions. Excavation is not recommended except for surface clearance or micro-instrument placement.

• Collapse Features and Lava Tubes: These areas may offer natural voids beneath thin regolith cover. While surface access is limited, vertical shaft excavation and tunneling may be feasible with appropriate ground control modeling.

• Megaregolith: Beneath the regolith, the megaregolith consists of fractured bedrock, impact breccia, and blocky material. This zone is only relevant for deep excavation, anchoring, or tunneling. It behaves similarly to heavily jointed rock on Earth and requires full excavation engineering design⁷.

These terrain classes must not be treated as visual categories only. They influence penetration resistance, particle cohesion, equipment wear, and cut stability (see Table 2). Contractors should not rely on average regolith depths. Instead, excavation planning must reference the terrain-specific depth range and variability indicators derived from radar, thermal inertia, and prior mission datasets.

Table 2– Provisional Regolith Depth and Excavation Feasibility by Terrain

Terrain Type	Estimated Regolith Thickness	Excavability Feasibility	Notes	References
Mare Plains	2-8 m	✔ L1–L3 feasible. L4 possible with controlled slope. L5 not feasible in most areas.	Fine-grained, compacted, limited overburden.	Apollo 11–12⁴; Chang’e-5⁵
Highlands	8-15+ m	✔ L1–L5 feasible with tool adaptation.	Thick, mature regolith. High block content.	Apollo 16⁴; LRO/Lunar Sourcebook⁶
SPA Basin/Farside	Variable (1-10 m)	⚠ L1–L3 feasible with radar validation. L4–L5 conditional.	Requires localized GPR confirmation. Fractured substrate is common.	Chang’e-4⁵; Oberbeck et al. (1973)⁸
Transitional Basaltic Zones	3-10 m	✔ L1–L3 feasible. L4 may require slope design.	Variable stratigraphy. Risk of embedded rock.	Apollo 14⁴; Snoble (2019)⁹
Crater Rims/Ejecta Blankets	<1-2 m	⚠ L1 only. L2+ not feasible due to slope and block instability.	High fragment content. Low regolith cover.	Apollo observations; Oberbeck et al.⁸
Lava Tubes Collapse Zones	0.5-5 m (surface); unknown void	✔ L1–L3 feasible. L5 possible if shaft access and roof stability are confirmed.	High-value zones for subsurface structures. Requires detailed geotechnical validation.	Haruyama et al. (2009)¹⁰; Coombs & Hawke¹¹
Megaregolith	>15 m (beneath regolith	⚠ L4–L5 only. Requires TBM or penetrator tools. Full excavation design required.	Fractured, jointed structure. Not suitable for shallow tools.	Carrier et al.⁴; Snoble⁹; Q-system³

Note: The values and excavation feasibility estimates provided in Table 1 are provisional and based on available mission datasets (Apollo, Chang’e, LRO), published regolith stratigraphy models, and analog interpretation from terrestrial excavation frameworks. Terrain-specific regolith thicknesses and excavation classes are generalized and do not account for localized anomalies, block content heterogeneity, or subsurface voids. These classifications are intended for preliminary planning purposes and must not be used in place of detailed site-specific geotechnical investigations. Ground truth validation using in-situ geophysical methods (e.g., GPR, seismic sounding, core sampling) remains essential before any excavation is executed. The term “megaregolith” is used following lunar geological convention to describe fractured bedrock beneath the regolith layer and should not be assumed uniform across basin or highland terrains.

4. Tool Compatibility by Terrain and Excavation Zone

Excavation performance on the Moon is a function of both the excavation zone (L1–L5) and the specific terrain class. A system or tool that performs well in one zone-terrain combination may fail in another due to differences in regolith thickness, particle angularity, embedded rock content, and load response under 1/6 g. Selection of excavation systems must therefore be made with full consideration of the terrain profile and the expected range of mechanical demands.

Earth-based projects typically rely on well-established correlations between tool class and material behavior, guided by empirical performance data and classification schemes. In lunar conditions, empirical datasets are limited, but available mission reports and simulation results allow us to define an operational matrix linking excavation depth, terrain type, and appropriate tool classes. This matrix does not replace performance testing but serves as an engineering pre-screening tool.

The table below summarizes tool feasibility across zoning classes and terrain types, integrating operational constraints such as regolith penetration resistance, slope stability, and potential for block interference.

Table 3 – Excavation Tool Feasibility Matrix by Terrain and Zone

Note	L1	L2	L3	L4	L5	Terrain Compatibility	Notes
Regolith brush/blower	✔	✘	✘	✘	✘	All except crater rims	Surface dust removal only. Not effective on compacted soils.
Light trenchers/rotary blade	✔	✔	✘	✘	✘	Mare, highlands	Feasible for shallow cuts. Boulder interference must be assessed.
Medium backhoe/articulated arm	✔	✔	✔	✘	✘	Highlands, mare basins	Suitable for cable trenches and small pits.
Heavy-duty trencher	✘	✔	✔	✔	✘	Highlands, transitional	Requires regolith depth >1.5 m. Use limited in thin cover zones.
Excavator with slope support	✘	✘	✔	✔	✘	Highlands, lava tubes (entry cut)	L4 works only where regolith depth supports benching.
TBM or mechanized excavator	✘	✘	✘	✘	✔	Megaregolith, deep highlands	Requires full design and ground control. Used for vaulting and anchoring.
Vertical penetrator or raiseboring machines	✘	✘	✘	✘	✔	Thick regolith sites, megaregolith zones	Experimental. Deployment depends on gravity anchoring and resistivity.

Note: The tool applicability ratings in this table are based on inferred regolith mechanical properties, available mission data, and terrestrial excavation analogs. These classifications are intended for preliminary system selection and early-stage design studies. Actual performance depends on site-specific conditions, including regolith thickness, boulder content, cohesion, slope geometry, and tool-soil interaction under reduced gravity. The compatibility indicators (✔/✘) are qualitative and do not replace performance validation. Tool deployment must be preceded by in situ geotechnical characterization and full mechanical integration modeling. TBM and penetrator systems remain experimental for lunar application and require advanced ground control and safety assessments. No operational heritage currently exists for subsurface excavation tools on the Moon.

5. Tunneling and Subsurface Excavation Feasibility

Subsurface excavation on the Moon represents a critical frontier for infrastructure protection, radiation shielding, and long-duration habitat stability. Unlike shallow trenching, which operates within the regolith layer (typically up to 5–10 meters), tunneling demands interaction with deeper and mechanically distinct geological units, including the megaregolith. These layers present higher bearing capacity and thermal stability but also impose significantly more complex excavation and ground control challenges.

Engineering Context

On Earth, subsurface excavations in rock require detailed ground characterization, empirical classification systems (e.g., RMR, Q-system), and the use of TBM, drill-and-blast, or mechanical full-face equipment. On the Moon, the absence of atmospheric pressure, gravity at one-sixth Earth’s value, and unknown joint patterns introduce nontrivial differences in behavior. No lunar TBM has been developed or tested in situ, and the mechanical properties of megaregolith, including joint spacing, in-situ stress fields, and fracture propagation in vacuum, remain only partially understood.

Feasibility assessments must begin with location-specific depth models, stratigraphy (GPR) and (AVG), and seismic impedance contrasts. Candidate sites for tunneling include:

• Highland plateaus with >10 m regolith cover

• Lava tube roofs with verified overburden thickness

• Mare upland transitions with slope shelter

• SPA basin zones with fractured basaltic base

Tunneling Zones and Tool Constraints

Excavation zones L4 and L5 are the only classes considered viable for tunneling. L5, in particular, assumes mechanical tool deployment (e.g., shielded TBM or segmented cutterhead) and requires prior modeling of overburden stability, cutterhead penetration rates, and tool-soil interaction in low gravity.

The following constraints must be considered for any subsurface excavation planning:

• Minimum regolith thickness above tunnel crown: 3–5 m

• Allowable slope for entry ramp: <18° in loose regolith

• Need for internal structural lining: Mandatory for pressurized environments

• Ground monitoring requirements: GPR arrays, displacement sensors

• Anchoring and bracing: Critical due to the absence of confining pressure

Technical Note

Lava tubes may offer natural volumes that reduce the need for full mechanical excavation. However, their entry points, internal span integrity, and collapse risk must be validated through orbital radar and robotic scouting. Haruyama et al. (2009) identified potential tubes with >20 m ceiling thickness, but engineering feasibility requires precise modeling of the roof span under lunar stress fields.

6. Geotechnical Risk Classification and Mission Integration

While excavation zoning (L1–L5) defines operational demands by depth and structural application, it does not account for geological uncertainty or site-specific unpredictability. These aspects are critical in lunar environments where direct geotechnical investigation is limited, and terrain conditions vary sharply even within a few hundred meters. To address this gap, we introduce a provisional geotechnical risk classification system for lunar surface works.

This risk framework follows terrestrial analogs, such as Bieniawski’s Rock Mass Rating (RMR), Hoek-Brown’s GSI, and the Q-system, by integrating factors such as regolith thickness variability, boulder content, slope angle, and presence of subsurface anomalies. However, it is adapted to the unique realities of the Moon: absence of groundwater, low gravity, vacuum exposure, and limited ground truth.

Geotechnical Risk Classes

Risk Class	Definition	Typical Terrain	Key Engineering Implications
Class I	Well-characterized site. Known regolith depth and composition. Low slope and block content.	Mare plains; Apollo-verified zones	Minimal investigation needed. L1–L3 feasible with light tools. L4 possible with slope control.
Class II	Partially constrained site. Moderate regolith variability, slope gradients <15°, localized boulders.	Highlands near Apollo 16; Chang’e-5 landing site	Requires GPR and AVG validation. Suitable for L1–L4 with excavation monitoring. Site prep mandatory.
Class III	High uncertainty. Unknown regolith thickness, complex slope geometry, blocky or fractured surface.	SPA basin, farside sites, crater rims	GPR and seismic validation are required. L4–L5 is only feasible with structural modeling and support.

This risk classification is not intended to be prescriptive but rather to support risk-aware mission planning. It allows programmatic stakeholders to match mission objectives (e.g. anchoring, ISRU trenching, shielding) with appropriate terrain and equipment strategies. For example:

• A surface ISRU facility intended for robotic deployment with minimal excavation should be located in a Class I zone with regolith thickness validated by prior cores or GPR.

• A pressurized subsurface vault for human use must be placed only in Class III sites if accompanied by structural design, entry slope control, and active monitoring.

Mission Integration

This classification enables the development of excavation-aware site selection protocols. Instead of choosing sites solely based on sunlight, communication, or resource availability, mission planners can now layer geotechnical risk into the decision-making process. This shifts excavation planning from an afterthought to a core element of lunar infrastructure development.

Furthermore, these risk classes inform the prioritization of robotic precursor tasks, including:

• Ground Penetrating Radar (GPR) sweeps

• Seismic refraction surveys

• Cone penetrometer deployments

• Slope stability imaging

By integrating zoning classes (L1–L5) with geotechnical risk (Class I–III), a structured approach to lunar excavation becomes feasible, scalable, and resilient to site uncertainty.

Engineering Parameters and Reference Ranges

Any excavation or structural deployment on the Moon requires a minimum dataset of geotechnical properties. Unlike Earth, where site investigations can rely on borehole networks, laboratory testing, and back-analysis from previous works, lunar engineering must often proceed with minimal in-situ data. Nevertheless, many controlled experiments, mission returns, and remote sensing efforts have provided a working basis for estimating key soil parameters (see Table 4).

The following engineering parameters are synthesized from the Apollo mission core returns, Lunar Sourcebook, Chang’e-5 remote and returned data, and validated mechanical simulations in reduced gravity. These reference values are intended for preliminary design use and must be adjusted when localized in-situ data becomes available.

Table 4 - Reference Geotechnical Parameters for Lunar Regolith and Megaregolith

Parameter	Typical Range	Notes/Applicability	References
Bulk Density (ρ)	1.3–1.9 g/cm³	Increases with depth due to overburden and compaction.	Apollo cores, Chang’e-5⁵
Porosity	40–55%	Highest in upper 30 cm. Drops significantly below 50 cm.	Carrier et al.⁴; Snoble⁹
Internal Friction Angle (ϕ)	30–50°	Angular particle shape and vacuum friction enhance shear resistance.	Mitchell⁷; NASA Tech Memos
Cohesion (c)	0.1–1.5 kPa	Low cohesion. Electrostatic effects may increase apparent cohesion on surface.	Heiken et al.⁶; NASA TP-2008-7
Unconfined Compressive Strength (UCS)	10–100 kPa (regolith); >1 MPa (megaregolith)	Regolith: loose to dense. Megaregolith inferred from Apollo seismic data and analog rock samples.	Carrier et al.⁴; Q-system³
Modulus of Elasticity (E)	1–10 MPa (regolith); 100+ MPa (megaregolith)	Regolith modulus increases with depth and confinement. Megaregolith varies based on fracturing and joints.	Snoble⁹; Hoek & Brown²
Permeability (k)	~10⁻⁸ m/s (very low)	Nominally negligible for fluid migration. No pore water; vapor diffusion only.	Apollo testing data
Bearing Capacity (shallow)	10–80 kPa	Highly dependent on density, cohesion, and contact area. Requires full pressure distribution modeling.	Mitchell⁷; Chang’e-5 radar⁵
Thermal Conductivity (λ)	0.009–0.03 W/m·K (surface)	Increases slightly with depth. Important for structural thermal insulation modeling.	Apollo Heat Flow Experiment

Design Considerations

• Excavation force estimates must be based on real penetration resistance curves, not Earth equivalents. Both cohesionless flow and block interference affect tool dynamics.

• Foundations for landing pads, ISRU skids, and vaults must assume a wide envelope of bearing capacities unless site-specific stiffness and compressibility are validated.

• Slope stability calculations must account for lunar gravity, cohesion-friction interaction, and near-zero atmospheric damping. Traditional Earth-based infinite slope models must be recalibrated.

• Shielding structures (e.g., regolith berms) require compaction modeling under lunar vacuum conditions. Passive placement will not achieve design density.

  
  

This dataset provides the minimum required parameters to size equipment, select excavation methods, and design passive or active stabilization systems. However, it is not suitable for final structural design without in-situ verification.

8. Field Summary for Contractors: Excavation Feasibility Matrix

This section provides a consolidated field-level guide to assess excavation feasibility across major lunar terrains. It is structured to support engineering contractors and mission integrators who require a preliminary reference to match terrain conditions with excavation classes, tool categories, and anticipated construction demands (see Table 5).

The matrix below combines:

• Terrain classification (from geological mapping and remote sensing)

• Expected regolith thickness (per mission-derived data)

• Applicable excavation zones (L1–L5)

• Tool compatibility

• Likely construction types feasible for each context

Table 5 - Excavation Planning Matrix for Lunar Engineering Contractors

Terrain	Est. Regolith Depth	Excavation Zones Feasible	Tool Class Examples	Feasible Infrastructure
Mare Plains	2–8 m	L1–L3 (L4 with benching)	Rotary blades, backhoe, light trencher	ISRU trenching, cable routing, shallow utility pits
Highlands	8–15+ m	L1–L5	Medium/heavy trencher, excavator, TBM	Anchoring bases, regolith vaults, thermal shielding berms
SPA Basin / Farside Zones	1–10 m (variable)	L1–L3 (L4–L5 with modeling)	Robotic trenchers + GPR, articulated tools	Instrument vaults, robotic bays, shallow anchorage
Crater Rims / Ejecta Zones	<1–2 m	L1 only	Regolith blower, surface scraper	Passive shielding fill, dust clearing for surface pads
Transitional Basaltic Zones	3–10 m	L1–L3 (L4 conditional)	Trencher, excavator with slope control	Cable corridors, ramp cuts, regolith pile stabilization
Lava Tube Collapse Sites	0.5–5 m (surface)	L1–L3 (L5 with structural support)	Excavator with bracing, vertical shaft drill	Subsurface vaulting, habitat embedding, and ISRU material storage
Megaregolith Interfaces	>15 m (beneath regolith)	L4–L5 only	TBM, vertical penetrator, shielded cutterhead	Deep vaults, regolith-anchored modules, and tunnel segments

Notes for Contractors:

• Excavation Zones (L1–L5): Refer to Section 3 for definitions and depth thresholds.

• Tool Classes: Must be selected based on regolith physical parameters (see Table 3) and slope geometry.

• Risk Classes: Consult Section 6. Class II and III sites require ground validation before tool mobilization.

• Operational Constraints: Vacuum-induced tool overheating, fine particle infiltration, and electrostatic lifting must be factored into tool design and housing.

Recommendations for Field Use:

This matrix should be used as a preliminary screening tool in mission design reviews, site selection workshops, and early-stage RFI/RFP planning for lunar construction systems. Values must be confirmed through remote sensing overlays, robotic scouting, and full geotechnical modeling before detailed excavation engineering is issued.

9. Final Remarks and Recommendations

Lunar excavation is no longer a speculative task. As permanent infrastructure moves from concept to implementation, excavation planning must evolve from generic approximations to risk-informed, zone-specific engineering frameworks. This document has presented a provisional but operationally grounded classification system for excavation zones (L1–L5), risk classes (I–III), tool compatibility, and geotechnical reference values based on current mission data.

Several key recommendations emerge from this work:

• Excavation must be embedded in the early design phase of all surface systems, including landing pads, ISRU plants, radiation shielding, anchoring, and mobility corridors. Delaying excavation analysis introduces mission and safety risk.

• Zoning and risk mapping should be geospatially layered on site selection maps using terrain, slope, regolith thickness, and radar-inferred structures. These overlays must guide both robotic reconnaissance and infrastructure layout.

• Contractors must rely on tiered excavation feasibility planning, using tools like the matrices in Sections 3 and 8 to estimate depth requirements, tool-class boundaries, and construction compatibility.

• No excavation planning should proceed without geotechnical ground truth. Remote sensing, GPR, and seismic profiling must precede tool deployment and civil works. Without this step, cost and failure risk escalate rapidly.

• Regolith is not a uniform material. Mechanical properties vary drastically by location and depth. Construction assumptions based on “average” values are insufficient. Design must consider best-case and worst-case bounds.

  
  

This framework is intended to serve as a reference foundation for contractors, system integrators, and mission architects tasked with enabling surface operations. It is understood that values and classifications will evolve with further robotic missions and in sit validation. Therefore, this document will remain a living reference and will be updated as ground truth data from future missions, including Artemis, Chang’e, and private landers, becomes available.

10. References

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    2. Hoek, E., & Brown, E. T. (1980). Underground Excavations in Rock. Institution of Mining and Metallurgy.

    3. Barton, N., Lien, R., & Lunde, J. (1974). Engineering classification of rock masses for the design of tunnel support. Rock Mechanics, 6(4), 189–236.

    4. Carrier, W. D., Olhoeft, G. R., & Mendell, W. (1991). Physical Properties of the Lunar Surface. In G. H. Heiken, D. T. Vaniman, & B. M. French (Eds.), The Lunar Sourcebook (pp. 475–594). Cambridge University Press.

    5. Lin, Y., Liu, J., & Wang, Y. (2023). Chang’e-5 mission results and lunar regolith properties from core sample analysis. Acta Geotechnica, 17(4), 1723–1739. DOI:10.1007/s11440-022-01314-0

    6. Heiken, G. H., Vaniman, D. T., & French, B. M. (1991). The Lunar Sourcebook: A User’s Guide to the Moon. Cambridge University Press.

    7. Mitchell, J. K. (1976). Fundamentals of Soil Behavior. Wiley.

    8. Oberbeck, V. R., Quaide, W. L., & Greeley, R. (1973). Comparative Lunar Regolith Studies: Block Abundance and Crater Ejecta. NASA Technical Note D-7245.

    9. Snoble, J. M. (2019). Geotechnical Engineering Approaches for Lunar ISRU Infrastructure. NASA Lunar Surface Innovation Consortium (LSIC) Proceedings.

    10. Haruyama, J., et al. (2009). Possible lunar lava tube skylight observed by SELENE cameras. Geophysical Research Letters, 36(21), L21206. DOI:10.1029/2009GL040635.

    11. Coombs, C. R., & Hawke, B. R. (1992). A search for intact lava tubes on the Moon: Possible lunar base habitats. In Lunar Bases and Space Activities of the 21st Century (pp. 219–229). Houston, TX: Lunar and Planetary Institute.

© 2025 Roberto de Moraes for Space Geotech

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