Extraterrestrial
Gunite Construction
System
Surface stabilization and infrastructure construction for lunar and planetary operations. A dry-mix regolith projection system engineered to mitigate plume-induced regolith displacement and to build the hardened surface infrastructure required for sustained operations in reduced-gravity environments.
FIG. 01 — High-thrust descent plume displacing unbound lunar regolith
Starship Plume Interaction
with Unbound Regolith —
An Unsolved Infrastructure Problem
During Starship-class lunar descent, high-thrust engines generate supersonic exhaust plumes that interact violently with the unbound regolith surface. The resulting ejecta field poses an existential risk to surface infrastructure. Without hardened landing pads, every landing degrades the operational environment — and no scalable solution currently exists.
Hypervelocity Ejecta Field
Starship engine plumes accelerate regolith particles to ballistic velocities — creating a debris field capable of damaging spacecraft, equipment, and surface infrastructure within several kilometers of the landing zone.
Sensor & Optic Contamination
Electrostatically charged lunar dust adheres permanently to optical surfaces, solar panels, and thermal radiators. Each unprotected landing compounds the degradation of mission-critical systems.
Progressive Surface Erosion
Repeated high-thrust landings excavate craters beneath landing legs and erode the surrounding surface, destabilizing any adjacent infrastructure and making each successive landing more hazardous.
No Scalable Hardening Method
Sintering, microwave melting, and binder jetting all require high energy input, complex equipment, or depend on gravity for material compaction — making them impractical at the scale and speed required for Artemis-class operations.
Kinetic Compaction via
Dry-Mix Pneumatic Projection
EGCS adapts the proven 100-year-old gunite process for extraterrestrial environments — replacing gravity-dependent compaction with velocity-driven kinetic energy. The result is a construction system that works harder in low gravity, not against it.
Dry Regolith Transport
Processed lunar regolith is pneumatically conveyed through vacuum-rated hose assemblies using compressed inert gas — no water required in the transport phase.
Binder Injection at Nozzle
A precision binder injection ring introduces binding agent at the nozzle tip — not in the hose — eliminating premature hydration and clogging in the transport system.
High-Velocity Projection (60–100 m/s)
The mixed material exits the nozzle at 60–100 m/s. Upon impact, kinetic energy compacts the regolith-binder matrix — achieving structural density independent of gravitational force, with strength 2.7–3.4× greater than gravity-placed equivalents.
Gravity-Independent Compaction
Unlike gravity-settled concrete, EGCS compaction is driven by impact velocity. At 1/6g lunar gravity, the system performs equivalently to Earth-based gunite — or better.
Core Engineering Insight
Conventional concrete and cement systems rely on gravitational force to settle and compact aggregates. In a 1/6g environment, this results in increased porosity and reduced structural density. EGCS eliminates this dependency entirely — compaction is achieved through kinetic energy at impact, not gravitational settlement. The lower gravity may actually reduce rebound losses, improving material efficiency compared to Earth applications.
System Performance
Parameters
All values represent typical operating ranges or preliminary estimates. Performance parameters are subject to revision following terrestrial prototype testing and vacuum chamber validation.
Projection Velocity
60–100+ m/s
Typical operating range; adjustable via gas pressure
Regolith-binder mixture is projected at high velocity through the nozzle assembly. Exit velocity is a function of gas pressure, hose length, and nozzle geometry — and can be tuned to application requirements.
Compaction Mechanism
Kinetic Energy Impact
Gravity-independent
Compaction is achieved through the kinetic energy of the projected material at the moment of impact — not through gravitational settlement. This mechanism is unaffected by reduced-gravity environments.
Compressive Strength
~2.7–3.4× vs gravity-placed
Preliminary estimate; subject to validation testing
Pneumatically projected concrete specimens in terrestrial gunite applications consistently demonstrate higher compressive strength than equivalent gravity-placed mixes. Extrapolation to lunar conditions requires vacuum chamber validation.
Environment Compatibility
Vacuum + Reduced Gravity
Hard vacuum to 1 atm; 0g to 1g
The dry-mix transport phase requires no atmospheric pressure differential. Binder introduction occurs at the nozzle tip, eliminating premature hydration in the transport system. All seals and elastomers are specified for hard vacuum operation.
Rebound Loss
Potentially lower than Earth applications
Hypothesis pending validation
In reduced gravity, the lower mass-acceleration of rebound particles may result in reduced rebound losses compared to terrestrial gunite applications, improving material efficiency. This hypothesis requires experimental confirmation.
Thermal Operating Range
−170°C to +120°C
Lunar surface thermal cycle
Hose assemblies, seals, and nozzle components are specified for the full lunar thermal cycle. Material selection prioritizes fluoropolymer and FFKM elastomers with demonstrated performance across this temperature range.
Integrated System Architecture
Regolith Collection & Processing
Autonomous surface collection of lunar regolith followed by mechanical sieving to target particle size distribution (0.1–2mm). Electrostatic separation removes glass beads and fine dust fractions that would compromise nozzle performance.
Binder Delivery System
Pressurized storage of binding agent (sulfur-based, geopolymer, or water-based depending on mission profile). Precision metering pump delivers binder to the injection ring at controlled flow rates synchronized with regolith throughput.
Pneumatic Propulsion System
Compressed inert gas (nitrogen or CO₂) propels the dry regolith mix through the hose system. Gas pressure is regulated to achieve target exit velocity at the nozzle. Closed-loop pressure control compensates for hose length and elevation changes.
Material Conveyance (Hose Assembly)
Vacuum-rated hose assemblies constructed from PTFE-lined inner bore with braided stainless steel reinforcement and fluoropolymer outer jacket. Rated for abrasive regolith transport in thermal vacuum from -170°C to +120°C.
Spray Nozzle Assembly
The primary engineered component of EGCS. Features a venturi mixing chamber, precision binder injection ring with evenly-spaced micro-jets, and a replaceable tungsten carbide wear tip. Designed for vacuum operation with no atmospheric pressure differential dependency.
Robotic Platform Integration
The spray nozzle assembly is mounted on a 6-DOF robotic arm integrated with a tracked or wheeled lunar rover platform. Autonomous path planning enables systematic coverage of target surfaces. Teleoperation capability provides human oversight for critical operations.
The EGCS Nozzle
Assembly
The spray nozzle is the critical engineered component of the EGCS system. It solves the fundamental challenge of introducing a reactive binder into a high-velocity dry aggregate stream in a vacuum environment, without premature hydration, clogging, or pressure loss.
Binder Injection Ring
Core Patent ConceptA circular manifold with evenly-spaced micro-jets injects binder uniformly into the dry aggregate stream. Jet geometry is optimized for complete coverage without turbulent disruption of the flow pattern.
Venturi Mixing Chamber
Fluid Dynamics ValidatedThe venturi geometry accelerates the aggregate stream while creating a low-pressure zone that draws binder into intimate contact with regolith particles. Mixing occurs in milliseconds before nozzle exit.
Replaceable Wear Tip
Materials SpecifiedLunar regolith contains sharp angular glass particles with extreme abrasivity. The nozzle tip is a field-replaceable tungsten carbide insert, extending operational life without full nozzle replacement.
Vacuum-Compatible Operation
Elastomers SelectedAll seals use FFKM (Kalrez) or fluorosilicone elastomers rated for hard vacuum. No atmospheric pressure differential is required for operation — the system functions in any ambient pressure from 1 atm to 10⁻¹² torr.
FIG. 02A — EGCS Nozzle Assembly — Longitudinal cross-section
Material Specifications
Infrastructure Applications
Landing pad stabilization is the primary near-term application — but EGCS is designed as a full extraterrestrial construction platform. The same system that hardens a landing pad can build radiation shielding, surface roads, and structural shells.
Lunar Landing Pad Stabilization
Hardened launch/landing surfaces constructed from sprayed regolith concrete eliminate plume-induced erosion. EGCS can construct pads capable of withstanding repeated Starship-class vehicle operations.
Habitat Radiation Shielding
Inflatable habitat structures can be coated with successive layers of sprayed regolith concrete to provide radiation shielding equivalent to several meters of lunar soil — without excavation.
Surface Infrastructure
Roads, equipment pads, and traversal paths can be hardened using EGCS, reducing rover wheel wear, dust contamination, and surface instability across the lunar base operational area.
Lava Tube Reinforcement
Lunar lava tubes represent ideal habitat locations — large, thermally stable, naturally radiation-shielded. EGCS can stabilize tube walls and construct interior structures using in-situ regolith.
Three-Stage
Validation Program
The EGCS validation program progresses from terrestrial prototype testing through thermal vacuum characterization to reduced-gravity confirmation, establishing the evidence base required for lunar deployment.
Terrestrial Prototype Testing
Full-scale nozzle assembly fabrication and bench testing
Gunite system trials with lunar regolith simulant (JSC-1A / LMS-1)
Compressive strength measurement of sprayed specimens at varying velocities
Nozzle wear rate characterization with abrasive simulant
Binder injection uniformity and mixing efficiency assessment
Rebound loss quantification under controlled conditions
Thermal Vacuum Chamber Testing
Pneumatic transport behavior in hard vacuum environment
Spray pattern characterization at simulated lunar pressure (<10⁻⁶ torr)
Seal and elastomer performance across lunar thermal cycle (−170°C to +120°C)
Binder injection and mixing behavior in vacuum
Cured specimen strength comparison: vacuum vs. ambient conditions
Outgassing characterization of binder candidates
Reduced-Gravity Validation
Parabolic flight testing of pneumatic transport at 1/6g
Spray pattern and rebound behavior in reduced gravity
Compaction efficiency comparison: 1g vs. 1/6g
Regolith simulant flow dynamics in reduced-gravity environment
Robotic arm integration and spray path accuracy testing
Structural specimen production and strength testing at 1/6g conditions
EGCS vs. Competing
Lunar Construction Approaches
A direct comparison of key engineering parameters across the primary approaches currently under development for lunar surface construction.
ICON Project Olympus is the most well-funded competing approach, having received a $57.2M NASA SBIR Phase III contract in 2022 (contract through 2028) to develop its Laser Vitreous Multi-material Transformation (LVMT) system. ICON's February 2025 Duneflow experiment aboard a Blue Origin suborbital flight confirmed that regolith behavior in 1/6g remains an active unresolved challenge for laser-based approaches — a problem EGCS avoids entirely through kinetic compaction.
Metric
EGCS
Dry-Mix Pneumatic Projection
ICON Olympus
Laser Vitreous Multi-material Transformation
$57.2M NASA SBIR Phase III
Regolith Sintering
Microwave / Solar Thermal Fusion
Binder Jetting
Liquid Binder on Powder Bed
Contour Crafting
Wet Extrusion Layer-by-Layer (NASA NIAC)
NASA NIAC — Multiple Awards
Compaction Mechanism
How material density is achieved
Kinetic energy at impact — gravity-independent
Laser melting — layer-by-layer deposition
Thermal fusion — requires sustained heat
Gravity-settled powder bed — layer deposition
Wet extrusion — pre-mixed regolith concrete deposited layer by layer
Gravity Dependence
Sensitivity to reduced-gravity environment
None — compaction driven by velocity
Under study — Duneflow experiment (Feb 2025) still characterizing regolith flow in 1/6g
Significant — melt pool behavior changes in low-g
High — powder bed requires gravity to settle
High — wet concrete flow and layer settling dependent on gravity
Energy Requirement
Power draw for primary process
Low — compressed gas propulsion
Very high — high-powered laser arrays
Very high — microwave or concentrated solar
Moderate — binder pump and print head
Moderate — pump, nozzle, gantry drive system
Equipment Complexity
Number of interdependent subsystems
Moderate — hose, nozzle, gas supply
High — precision laser, optics, thermal management
Moderate — microwave array or solar concentrator
Moderate — print head, binder system, powder feed
High — gantry structure, concrete pump, water/binder supply
Formwork Required
Need for molds or support structures
Minimal — conforms to any surface
None for open structures
Yes — requires containment for melt pool
Yes — requires contained powder bed
Yes — gantry must span full structure footprint
Irregular Surface Capability
Application to non-planar geometry
High — nozzle can reach any geometry
Moderate — constrained by gantry geometry
Low — limited to flat or simple geometries
Low — constrained to print volume
Low — constrained to gantry travel envelope
Vacuum Compatibility
Demonstrated operation in hard vacuum
Yes — no atmospheric dependency
Yes — designed for lunar vacuum
Partial — thermal management challenges in vacuum
Limited — binder chemistry changes in vacuum
Limited — wet mix chemistry and outgassing in vacuum unresolved
Repair & Maintenance
Field serviceability of wear components
High — replaceable WC wear tip
Low — laser optics require precision servicing
Low — integrated thermal systems
Moderate — print head replacement
Moderate — nozzle and pump components
Technology Readiness
TRL based on terrestrial heritage
TRL 3–4 (100+ yr terrestrial heritage)
TRL 4–5 (Earth prototype, lunar sim testing)
TRL 3–4 (lab demonstrations only)
TRL 3 (Earth only, no vacuum demonstration)
TRL 4 (Earth prototype; NASA 2014 competition winner)
NASA Funding Status
Active funded research program
Concept stage — SBIR Phase I target
Active — $57.2M contract through 2028
Research stage — NIAC / university programs
Research stage — university programs
NASA NIAC funded — Contour Crafting Corp. commercializing
Sources: NASA MMPACT, ICON Newsroom, published literature
Five-Phase Development Program
Phase I
Concept Validation
Months 1–18
$500K – $1.5M
Fluid dynamics modeling of vacuum pneumatic transport
Regolith simulant characterization and selection
Binder chemistry evaluation (sulfur, geopolymer, water-based)
Nozzle geometry CFD analysis
Literature review and prior art analysis
Phase II
Earth Prototype
Months 12–36
$1.5M – $4M
Full-scale nozzle assembly prototype fabrication
Gunite system testing with lunar regolith simulant (JSC-1A)
Compressive strength testing of sprayed specimens
Wear rate testing of nozzle components
Robotic arm integration proof-of-concept
Phase III
Vacuum Chamber Testing
Months 30–54
$3M – $8M
Thermal vacuum chamber testing at simulated lunar conditions
Material performance validation at -170°C to +120°C
Pneumatic transport behavior in vacuum environment
Seal and elastomer longevity testing
Spray pattern characterization in vacuum
Phase IV
Robotic Demonstration
Months 48–72
$5M – $15M
Full robotic EGCS platform development
Autonomous path planning and spray control software
Simulated lunar surface construction demonstration
Landing pad construction demonstration at 1:10 scale
System reliability and maintenance protocol development
Phase V
Lunar Pilot Mission
TBD (Artemis Program)
$50M – $200M
Small demonstration structure on lunar surface
Landing pad hardening at Artemis base camp site
In-situ performance data collection
Technology readiness level advancement to TRL 7+
Commercial licensing and partnership development
Translating Terrestrial
Expertise to
Extraterrestrial Applications
The EGCS concept originates from deep operational experience in gunite and shotcrete construction systems. The inventor brings decades of hands-on expertise in pneumatic material projection, nozzle design, and structural concrete applications — knowledge that directly informs the engineering approach to lunar construction.
The core insight is straightforward: gunite has been used on Earth for over 100 years precisely because it does not require complex formwork, achieves high compaction through kinetic energy, and can be applied to irregular surfaces by a skilled operator or robotic system. These same properties make it uniquely suited to the lunar construction challenge.
Gregory Althammer
Inventor, EGCS
Gunite Shotcrete Warehouse (GSW)
Founder of Gunite Shotcrete Warehouse, with extensive field experience in gunite system design, nozzle engineering, and structural concrete applications across industrial, civil, and specialty construction sectors.
Technical Foundation
Gunite Process
100+ years of terrestrial application — tunnels, domes, pools, refractory lining, structural repair
→ Direct process transfer to lunar application
Nozzle Engineering
Venturi mixing, wear-resistant materials, binder injection systems for abrasive materials
→ Core EGCS nozzle design expertise
Pneumatic Transport
Dry-mix conveyance through hose systems under pressure — established industrial practice
→ Vacuum-adapted transport system design
Material Science
Cementitious binders, aggregate selection, compressive strength optimization
→ Regolith-based concrete formulation
Construction Operations
Field deployment, equipment maintenance, quality control for sprayed concrete structures
→ Operational protocol development for lunar deployment
Seeking Collaboration for
Prototype Validation and
Extraterrestrial Construction Applications
EGCS is actively seeking collaboration for prototype validation, landing pad stabilization studies, and extraterrestrial construction applications. Engagement is open with aerospace agencies, commercial space operators, research institutions, and advanced construction technology organizations at any stage of the development process.
NASA SBIR/STTR
Phase I and Phase II research funding for concept validation and prototype development
Artemis Program Partners
Lunar surface infrastructure development for Artemis base camp and HLS mission support
Commercial Space Companies
SpaceX, Blue Origin, and lunar logistics companies requiring surface infrastructure solutions
Research Institutions
University and national laboratory partnerships for materials science and fluid dynamics research
Partnership Inquiry