From Closure Claims to Comparable Evidence

Two closure percentages can both be accurate while describing different accounting bases. One may describe food on a nutritional basis, another water as a share of demand, and a third a material stream within a reactor. A program or investment comparison becomes valid when the loop, denominator, duration, and system boundary are made explicit.

Setting the measurement contract before testing provides that common ground. NASA can apply it across architectures and test articles. Investors can use the same declared basis to distinguish technical progress from a milestone whose accounting boundary has changed. The discipline serves both communities because it leaves the evidence intelligible to those who inherit the next decision.

Decide the basis first

A minimum comparative dataset gives cultivation and regenerative life-support demonstrations a common review structure. Any percentage, mass, labor figure, or cost value becomes comparable after its numerator, denominator, duration, boundary, operating state, and uncertainty are stated. Without that context, a precise number may still carry an uncertain meaning.

For ORCA, this structure is prospective measurement infrastructure. Gastronaut is developing ORCA as a 2.0 m diameter standalone modular cultivation enclosure. A data dictionary or resource ledger does not prove technical or economic advantage. It makes a later claim answerable and preserves continuity as the program advances.

Three percentages, three different services

Tang and colleagues reported a four-person, 180-day demonstration with mean food closure of 55 percent and a peak of 70.8 percent. Atmosphere closure was 100 percent, water closure 100 percent, and solid-waste closure 87.7 percent (Tang et al. 2021). The study calls these material-closure measures, while the mass basis still requires confirmation before any cross-study comparison.

In Biosphere 2, Silverstone and Nelson followed eight crew members for two years. The system supplied about 80 percent of their nutritional needs. During the same closure, crew lost 10 to 20 percent of body mass, mostly in the first six months, while agriculture and food processing consumed about 45 percent of crew time (Silverstone and Nelson 1996). The nutritional percentage cannot be separated from its physiological and labor context. Calling it an 80 percent result would remove information that a decision-maker needs.

Samsonov and colleagues reported production sufficient for up to 76 percent of potable-water demand in their system context (Samsonov et al. 2004). That is a water-demand function. It cannot be combined with food contribution, atmosphere closure, or solid-waste processing as though the denominators were shared.

These studies answer different questions. Their values do not form a general closure estimate. Responsible comparison begins by keeping each loop, denominator, and operating burden visible.

Production and labor belong in the same account

EDEN ISS makes the boundary visible in both output and operator time. Zeidler and colleagues reported 646 kilograms of produce across two phases. On-site operator time was about four times remote-support time, but the source did not state operator counts (Zeidler et al. 2021). Crop mix, harvest definition, duration, and operating context qualify the mass. Task allocation and staffing qualify the labor ratio.

A mission record therefore needs edible and inedible mass, wet and dry basis, crop mix, area or volume, elapsed and active cultivation time, losses, and quality criteria. Its labor record needs hands-on crew time, remote support, scheduled work, unplanned maintenance, processing, cleaning, and scientific activity, together with operator count and skill assumptions. The people who sustain the system are part of its operating account, not an externality to it.

For investors, stable definitions keep milestone reporting tied to performance. A later demonstration earns a stronger result when performance changes while the reporting boundary remains fixed.

Cost requires a declared accounting basis

In the reviewed set, 15 of 78 T5 and T6 records named cost as an outcome. Thirty-one of those 78 mentioned cost somewhere. Across 150 analysable records, five reported values, each on a different basis. Sixty-six of 150 reported effects partly or not at all, and 73 omitted sample size.

Those records do not support a pooled cost estimate, nor do they show that cultivation lacks economic relevance. They establish why the accounting basis belongs before the test. Currency and year, development cost, fixed and recurring elements, launch assumptions, crew time, power, consumables, maintenance, replacement, waste processing, ground support, reliability, and time horizon can each alter the result.

The accounting evidence supports high confidence that the cited closure and cost figures cannot be compared without aligned boundaries and denominators. Confidence remains low regarding the relative system cost of candidate architectures. A common benchmark campaign with traceable formulas and parameter sources would raise it; boundary changes or unmeasured labor would lower it. The declared basis is therefore part of the evidence entrusted to the next reviewer.

The six-record contract

Six linked records can create a comparative dataset:

1. System boundary: included hardware, biological material, habitat services, crew functions, ground support, and interfaces.
2. Loop declaration: food, atmosphere, water, nutrients, solid waste, or another specified service, with the numerator and denominator for each percentage.
3. Time basis: test duration, startup and stabilization, nominal operation, faults, recovery, and downtime.
4. Resource ledger: power, water, gases, nutrients, consumables, spares, crew time, remote support, volume, and mass, with units and measurement method.
5. Output and quality record: edible and inedible biomass, nutrient or food contribution, accepted and rejected product, atmosphere or water service delivered, and uncertainty.
6. Reliability and intervention record: failure definition, exposure time, maintenance, replacement, recovery time, crew action, and retained function.

Raw measurements and configuration history remain beside the calculated indicators. Every derived closure percentage or economic figure points back to its source fields and formula. A reviewer can then change the boundary and recalculate the result with a clear view of what the summary contains. Such transparency allows disagreement to improve the analysis rather than obscure it.

Apply the contract to ORCA

Gastronaut can provide NASA a linked data dictionary, crop-readiness assessment, resource-accounting template, ground-validation plan, and ORCA operating-history structure for review. NASA has not validated these company materials. A jointly defined minimum dataset can revise them before a benchmark campaign.

Gastronaut’s internal record covers 1,042 ground growth cycles over 18 to 24 months. It can reveal available fields, missing data, recurring interventions, and candidate baseline crops. Flight, lunar, variable-gravity, reliability, biological-efficacy, and edited-line performance retain separate evidence status. ORCA remains approximately TRL 3 to 4 at the ground stage, with zero flight cycles and zero lunar cycles.

A joint data-standard session can select a reference mission segment, define system and loop boundaries, agree on units and formulas, and establish reporting requirements before baseline, nominal, and fault-recovery runs begin.

The campaign would then have one governing question: what service did the module provide, across what boundary and duration, with what resources, interventions, reliability, and uncertainty? NASA would receive a comparable acquisition record. Investors would receive a stable technical milestone. Both would be able to exercise their responsibilities from the same measurements and one declared basis.

References

Gastronaut. Environmental Control and Life Support: Evidence Synthesis. Evidence version frozen 21 Aug. 2026. Research synthesis.

Samsonov, Nikolai M., et al. 2004. https://doi.org/10.4271/2004-01-2489.

Silverstone, Sally E., and Mark Nelson. 1996. Advances in Space Research. https://doi.org/10.1016/0273-1177(95)00861-8.

Tang, Ya, et al. 2021. Life Sciences in Space Research. https://doi.org/10.1016/j.lssr.2021.08.001.

Zeidler, Conrad, et al. 2021. Life Sciences in Space Research. https://doi.org/10.1016/j.lssr.2021.06.003.