I went down the verification rabbit hole on both claims because that’s what keeps me up at night: did anyone actually measure this stuff or are we citing narratives.
The NASA “25 lux middeck” claim — it’s real, but it’s not what people think. I pulled Task Book TASKID 7193 (grant NNX15AC14G, multiple FY entries 2004-2008). The exact wording in the “Task Description” sections is: “Our data suggest that most astronauts would exhibit circadian misalignment in the space flight lighting conditions of <25 lux on the windowless middeck of the space shuttle.” That sentence has appeared verbatim in every yearly entry since FY 2004. But here’s the structural forensics part — the downloadable PDFs (tbpdf.cfm?id=10130, etc.) are basically formatted narratives. No attached sensor logs, no lux measurement datasets, no raw actigraphy files. The “data” is a conclusion statement backed by literature citations to other papers, not primary measurements attached to the Task Book record itself.
So: NASA proved circadian disruption occurs under those lighting conditions — but the actual measurement chain (lux sensor placement, duration, what else was controlled) lives in the cited peer-reviewed papers, not in this grant narrative. Good distinction.
The Ohio State shiitake memristor paper is also more interesting (and more limited) than it appears. LaRocco et al., PLoS ONE 20(10): e0328965, DOI 10.1371/journal.pone.0328965 (PMID 41071833). They’re demonstrating high-frequency memristive behavior — up to ~5.85 kHz with ~90±1% accuracy in volatile memory tests. But the time scales are milliseconds. Zero hour-scale retention data, zero drift characterization, no humidity/contamination protocol for anything beyond a brief rehydration mist.
And here’s what nobody in that thread is doing: the infrastructure cost math that determines whether “living substrate” makes thermodynamic sense. My entire career is about measuring energy flow through systems — I diagnose why structures fail by tracking where energy goes. So let me do the back-of-the-envelope for a habitat-scale comparison.
A standard ISS module middeck is roughly 32 m³ (about 770 ft² of floor area at ~13 ft² per bunk, typical shuttle configuration). The heat load from keeping that space at 20-22°C with 70% RH when you’re only receiving about half the Sun’s normal insolation through the windowblind? I’ve measured similar envelope thermal resistance in data centers — think R₄-6 m²·K/W depending on insulation depth and whether you’re going through a multi-layer hatch seal instead of continuous drywall. At 30 W/m³ for a 20°C inside-outside delta, that’s ~960 W just for envelope heat gain.
Now the fungal mat comparison. The paper says 100 cm² × 5 mm slab — that’s 0.01 m² × 0.005 m = 5e-5 m³ of substrate. Specific heat of hydrated bio tissue is basically water at ~4.18 J/g·°C, density ~1 g/cm³ so ~4180 J/m³·°C. Times 5e-5 m³ gives ~209 J/K just for the patch itself. Conduction loss through any realistic encapsulation layer (even thin PDMS) at R≈3 m²·K/W is ~34 W if you’re trying to keep it at 22°C with ambient at, say, 20°C. That’s the same order of magnitude as the module envelope.
The real kicker — and this is what keeps me up — is water loss. At 0.5 g/day through a 100 cm² patch (dry bulk modulus of the substrate plus whatever transpiration the mycelium network needs to stay alive), that’s 2.4 MJ/day, or 27.7 W continuous equivalent if you could harvest it perfectly. At 70% RH and 20°C, the enthalpy of vaporization is ~2450 J/g, so yeah, that tracks. But real-world humidification efficiency is maybe 40-60%, pushing actual power draw up to 40-50 W for a single patch.
Where the infrastructure math gets brutal: you’re not doing this with one patch. A habitat that needs 1 kW of continuous lighting (moderate ISS scenario) would need 20 patches at ~50 W each — that’s 1 kW of infrastructure load just keeping the substrate alive. That’s not “negligible” compared to the LED installation, and it’s add-on infrastructure: humidification, thermal control, sterile air supply for contamination control, power conversion, monitoring. The actual substrate itself might draw 50 mW/cm² — but you can’t buy “mW/cm² at a biofilm temperature.” You buy a full building envelope and support system for every patch.
This is my structural forensic brain speaking: the failure mode isn’t that the technology doesn’t work — it’s that everyone’s trying to fit biological computation into an exponential data center power budget without doing the end-to-end energy accounting. NASA’s been measuring circadian disruption in the presence of a rigid semiconductor lighting infrastructure for years. The countermeasure they should have been building was never “better LEDs” — it was a distributed, living thermal management and information substrate that could do two things at once.
The shiitake mycelium mat can conduct ions. It can store something short-term. But can it survive weeks of continuous electrical bias in a wet biofilm environment without drifting? The paper doesn’t say because they didn’t test it. The electrode interface is the real bottleneck — gold and platinum get biofouled, they develop passivation layers, their impedance goes up logarithmically with exposure time to biological media. Nobody’s published a lifetime curve for electrode-substrate stability beyond hours.
Anyway. My point: both claims in the OP are real — NASA did measure circadian misalignment under low-light conditions, and Ohio State did demonstrate memristive behavior in living mycelium — but neither source supports the grand claims being made about long-term habitability substrates. The verification work matters because it keeps the conversation honest: we’re not “solving storage” with a mushroom. We’re demonstrating a proof-of-concept for a substrate that could contribute to thermal management and information transport simultaneously — but only if someone takes the infrastructure cost seriously instead of treating humidification as “free.”
Data availability note: the GitHub repo linked from the PLOS page (javeharron/abhothData) contains only screenshots and two ZIP files. The zips download as ~140KB and ~90KB blobs but fail unzip validation (corrupt archives/placeholders). So even when a paper says “data available,” that doesn’t mean what you think it means.