FIRN and TARN use stored lunar water as two infrastructure assets at once: a protected resource reserve and a controllable thermal buffer for surface systems.
See the FIRN-S transient model ↗Track mass, availability, reservations and controlled transfer.
Deliver heat, absorb waste heat, and recover state on schedule.
CAIRN coordinates dual-state awareness, commitments and recovery.
Distributed local node for rovers, payloads and surface assets.
Controlled water inventory + internal heat-transfer architecture.
Separated from the berm; used for heat-sink state recovery.
Routine dry thermal service stays separate from water transfer.
The differentiator is the integrated architecture: FIRN/TARN treats the same water inventory as both a controlled resource reserve and a scheduled thermal utility.
Mass, grade, availability, reservations and transferability are made explicit. Withdrawing water reduces future thermal capacity.
Inventory becomes auditable rather than implicit.
Specific enthalpy, temperature distribution, phase fraction, service power and recovery margin become operational state variables.
Stored energy only matters if it can be delivered within the required temperature window.
Under what temperatures, masses, interface conductances, regeneration schedules and user counts does shared FIRN/TARN service outperform fully self-contained alternatives?
FIRN/TARN is best understood as three coupled layers: the water inventory, the thermal service hardware, and the software/operations layer that schedules use.
Water mass, grade, reservations, availability and transferability.
→WTAM, thermal routing, dry docks, phase management and external heat rejection.
→CAIRN coordinates state-of-charge, reservations, thermal loading/unloading and state recovery.
↗The network is shown as a systems architecture rather than a lunar “scene”: separate water, thermal-service, rejection and data paths with CAIRN coordinating state and schedules. v0.9 retains resilience scenarios, reservation status, network health and explicit service-prioritization logic to the interactive dispatch demonstrator below.
Both nodes share one architecture philosophy: FIRN is the compact edge utility; TARN is the shared hub.
Deployable near mobility routes and distributed surface assets such as rovers, payloads, instruments and small process equipment.
A larger reservoir class intended for multiple users, habitats, process loads, or clusters of FIRNs, with thermal-state recovery handled as an operational schedule.
Current physics, interfaces and mechanical definitions represent a working engineering baseline. They will continue to evolve through analysis, subsystem definition, simulation, bench testing and integrated validation.
Water mass, berm thickness, radiator area and service power remain DRM- and site-dependent. TBR/TBD values are screening inputs until promoted through analysis and test.
The interactive hardware inspector presents the current FIRN/TARN architecture as a manipulable engineering model. Geometry is schematic and supports subsystem, interface and packaging review while detailed CAD definition continues to mature.
Each architectural element is tied to its primary function, interfaces, engineering challenge and planned validation evidence.
This is presented as an engineering assembly. Toggle the major layers to see how berm, enclosure, WTAM, routing, radiator and interfaces relate.
Representative service cases connect architecture to mission duty: long-duration survival, local rover support, and habitat or process thermal buffering.
A bermed node holds a controlled water reserve that can buffer thermal loads through the long lunar night while remaining part of the overall water inventory.
A rover docks thermally to a nearby FIRN node and uses shared utility infrastructure instead of carrying every thermal contingency locally.
TARN operates as shared infrastructure for transient thermal loads, smoothing the operating picture across habitats, processes and clusters of FIRNs.
v0.6.1 replaces the generic efficiency calculator with a first-order enthalpy-state model aligned to the current FIRN/TARN baseline. It separates water mass, specific thermal state, parasitic load, design reserve and recovery direction.
This time-domain model follows the current FIRN-S reference logic minute-by-minute: constant user heat delivery, temperature-dependent parasitic loss, sensible cooling to 273.15 K, then latent heat extraction at the phase plateau.
The hardware becomes infrastructure only when paired with routing, sensing, docking, scheduling and an operating concept that can be measured and reused.
Conditioned water enters through an isolated transfer interface. Inventory, grade and reservation state become explicit machine-readable variables.
A switchable thermal path accepts or provides heat relative to the connected asset and the node’s present thermal state.
Dry thermal docks provide repeatable service without opening the resource loop, keeping routine thermal exchange separate from water transfer.
After heat-absorption service, the system can reject stored heat through the external radiator. After survival-heating service, thermal state must instead be restored by a heat source such as electrical, solar-thermal or compatible process heat.
Pull water out and available thermal reserve falls. Add thermal loading and the thermal state changes even if kilograms stay constant.
Heat is only useful at the right temperature. Load, accumulator and rejection path need overlapping operating windows; otherwise stored energy may exist without being deliverable as useful service.
CAIRN can sit above FIRN/TARN to orchestrate thermal loading and unloading, water charging and discharging, reservations, dual-state awareness and state-recovery scheduling across a distributed node network.
The public story stays credible when rooted in the closure work: water thermodynamics, freeze/thaw containment, dry thermal docking, radiator performance and regolith emplacement logic.
The regolith berm is a passive protection and insulation layer — with controlled heat rejection handled by a dedicated radiator. The architecture separates shielding/insulation from heat-rejection duty.
The near-term path is to retire the two dominant practical risks: repeatable freeze/thaw containment and predictable high-conductance thermal docking under lunar dust exposure.
Close the thermal model, inventory sizing, temperature-grade windows, state-recovery schedule and trade boundaries.
Demonstrate freeze/thaw containment, heat-transfer behavior, instrumentation and basic control logic.
Validate radiator heat rejection, dry-dock conductance and repeated mating and cycling performance.
Run WATERIG → FIRN demonstration, then scale toward TARN hub architecture validation.
The public-facing narrative is strongest when it is obviously grounded in engineering discipline and a concrete validation pathway.
The IAC paper is a selected technical slice of the broader FIRN/TARN technical definition and science baseline.
Back to top ↑The defensible contribution is architectural convergence: dual-state inventory management, standardized interfaces, resource/thermal separation, scheduled state recovery and a concrete validation framework.
Current values and product envelopes remain preliminary and should be treated as TBR/TBD unless later promoted through analysis or test.
eurus.space is developing FIRN/TARN from analytical closure toward bench hardware, interface testing and integrated resource-to-thermal demonstrations.