Loop. Separate every stream, measure every gram, turn urine, scraps and residue into fertiliser, feed and carbon, export the rest.

LOOP-S1 · function

Metabolic ledger and mass-balance accounting

Define what has to be closed per person per day and keep a live, sensor-reconciled ledger of water, carbon, O2, N, P, K and Na for every stream on the site.

How it works

The design basis is the NASA BVAD metabolic interface: an 82 kg reference adult consumes 0.895 kg O2, exhales 1.085 kg CO₂ (RQ 0.86), eats 0.80 kg dry food and drinks 3.2 kg water per day, and returns 1.42 kg urine water plus 0.061 kg urine solids, 0.13 kg faeces (wet) and 2.95 kg respiration/perspiration water. Every stream on site is metered (load cells on bins and tanks, flow meters, EC/pH/ORP/NH4/NO2/NO3 probes, CO₂/O2 NDIR and electrochemical cells) and the controller reconciles inflow minus outflow minus storage change for each element daily; the residual is the leak or fault signal. Biosphere 2 showed why this matters: material closure turned a mysterious O2 loss into an accountable carbon sink (concrete carbonation) found by 13C/12C mass balance. Closure is reported as the share of each element's daily throughput supplied from on-site recycling, by element, never as one headline percentage.

LOOP-S2 · function

Yellow loop: urine nutrient recovery

Turn urine, the most nutrient-dense excreted stream (8.8 g N/person/day), into a stable, legal, storable fertiliser and clean water instead of sewage.

How it works

Stored urine hydrolyses urea to ammonia and its pH rises, which drives NH3 loss and odour. Three proven routes stabilise it. (a) Nitrification: in a moving-bed biofilm reactor ammonia-oxidising bacteria convert about half the NH4+ to NO2-/NO3-, which drops pH and stops volatilisation; the ammonium-nitrate liquor is then distilled to a concentrate (the Aurin route, 71 W/cap primary energy for distillation, 13 W/cap for nitrification). (b) Struvite: dose Mg2+ (MgCl2, bittern or calcined magnesite) so MgNH4PO4.6H2O precipitates; about 95% of phosphate is removed but only a few percent of N. (c) Ion exchange: pass stored urine through natural clinoptilolite, which takes up NH4+ (and K+) and leaves salinity behind; regenerate with a salt rinse to a clean liquid fertiliser or apply the charged zeolite directly as a slow-release soil amendment. Nitrite accumulation and acid-tolerant AOB are the known failure modes of (a), so it needs online NO2- sensing and controlled dosing.

LOOP-S3 · function

Brown and green loop: solids, larvae, compost, digestion, char

Convert faeces, kitchen waste and inedible crop biomass (the dominant solid stream in any food-growing site) into feed, fertiliser, energy or stable carbon.

How it works

Inedible biomass is the elephant: a full BVAD crop diet produces 6.66 kg fresh inedible biomass per person per day, versus 0.13 kg faeces. Black soldier fly larvae eat wet kitchen waste over a cycle of roughly two weeks (v3 planning value 10–14 days) and, as prepupae, self-harvest by climbing a ramp into a bucket (shown in many operating demos), leaving frass. Thermophilic composting kills pathogens when the mass stays at 55 C or more for 3 days in-vessel (15 days with 5 turnings in a windrow), the US PFRP rule. Household anaerobic digesters (1–150 m³) convert wet organics to CH4/CO₂ and a liquid digestate, but sour (pH 5.3–6.1 observed) when overfed or cold. Pyrolysis at roughly 400–800 C turns dry lignocellulose into biochar, which locks carbon and, mainly on acidic tropical soils, raises yields. The Lunar Palace programme shows the frontier: solid-waste recovery rose from 41% degradation (105 days) to 67% (370 days) while water, O2 and urine reached near-total closure.

LOOP-S4 · function

Air loop: CO₂/O2 exchange between people, plants and algae

Use crops (and optionally microalgae) to fix CO₂ and return O2, with a pressure-buffered transfer between living and growing volumes.

How it works

Photosynthesis returns roughly one O2 per CO₂ fixed; how much area a person needs depends on light and crop: BVAD gives 56 g O2/m²/day for wheat and 7.8 for lettuce, so one person's 0.895 kg O2 needs about 16 m² of wheat or about 115 m² of lettuce at nominal rates (calculated). NASA LMLSTP Phase I kept one person's air for 15 days on 11.2 m² of high-light wheat; Phase III wheat supplied about 25% of four people's O2. Microalgae (Limnospira) in an air-lift photobioreactor reach about 1 g O2 per litre per day at high light, so a person needs roughly 860 L of reactor (calculated). A sealed volume needs a variable-volume 'lung' (Biosphere 2: 43,000 m³ of expansion on 140,000 m³) or it breathes through leaks; and any exposed fresh concrete or organic-rich soil is a hidden CO₂/O2 sink.

LOOP-S5 · function

Integrated bioregenerative loop (the analogue lineage)

Benchmark what whole-system closure has actually achieved, and where it broke, to set honest targets.

How it works

Four generations of experiments: BIOS-3 (1972–1984, 315 m³, 63 m² crops, 91% total closure, dried meat imported), Biosphere 2 (1991–93, 1.27 ha, ~10%/yr leak, O2 crash 21 to 14% in 16 months, O2 injected), CEEF in Aomori (2005–07, 150 m² crops, 2 crew + 2 goats, 82–95% of crew food), Lunar Palace 1 (2014, 105 days, 55% food; 2017–18, 370 days, 98.2% material closure, 99.7% urine, 67% solid waste). MELiSSA builds it compartment by compartment (C1 thermophilic waste degradation, C2 photoheterotrophs, C3 nitrifiers, C4a cyanobacteria, C4b higher plants, C5 crew) and is the only programme designed for deterministic control. The pattern: water and O2 close first, food second, solids and salts last.

LOOP-S6 · function

Safety gate: pathogens, pharmaceuticals, salts, plastics

Decide automatically which recycled product may go to edible crops, to ornamentals, or out of the site.

How it works

Each product carries a hazard profile: urine-derived fertilisers carry pharmaceuticals but plant uptake is tiny (0.00004–0.0002% of applied mass in lettuce, up to 2.5% of a therapeutic dose over 70 years of daily eating at worst-case spiking); struvite plus zeolite gave the purest product with the lowest uptake; frass concentrates plastics, phthalates and PFAS; recirculating hydroponics accumulates Na and B, so BVAD notes nutrient solutions are routinely dumped. The gate is a rules engine: hygienisation proof (time-temperature log), quarterly lab panels, online EC/Na and NO2-, and a default route to ornamentals or the sanitary holding tank when any proof is missing.

LOOP-S7 · function

Building-material loop: disassembly, passports, grown materials

Keep panels, hinges and infill in use across relocations and convert crop residue into building material instead of waste.

How it works

Design for disassembly uses reversible mechanical joints so components leave intact; a material passport (BIM/IFC-generated, e.g. Madaster) records composition, location and reuse value, linked to each part by an engraved QR code or RFID. Mycelium composites grow a fungal network (e.g. Trametes versicolor) through chopped hemp, flax or straw in moulds for days to weeks, then are heat-killed; they reach useful insulation performance but low strength, and 2026 work shows panels can be regrown and reused over multiple life cycles. In ORIJO the fold-flat panels are the reusable asset (Shikinen lease), while mycelium infill and biochar are the consumable carbon sinks.