Algae Photobioreactor Life-Support Simulator

Photobioreactor Controls

LED light intensity I₀ 700 μmol/m²/s

Reactor volume 25 L

Dilution rate D 0.30 /day

CO₂ sparge rate 100%

Crew size 3 astronauts

Culture State

Biomass density X

0.00 g/L

Growth rate μ

0.00 /day

O₂ output

0.0 L/hr

CO₂ scrubbed

0.0 L/hr

Reactor vs Crew O₂ Demand

Reactor supplies 0.0 L/hr against a crew demand of 0.0 L/hr.

DeficitbalancedSurplus

Cabin Atmosphere

Cabin O₂

20.90%

Cabin CO₂

0.040%

Sim clock: 0.0 h — cabin atmosphere holding steady.

How it works

Microalgae (e.g. Chlorella vulgaris) in a sealed, LED-lit photobioreactor photosynthesize, fixing CO₂ into biomass and releasing O₂ — the same bioregenerative life-support principle studied by ESA MELiSSA and NASA. Growth follows Monod light-limited kinetics with Beer–Lambert self-shading through the culture depth, then the reactor's net O₂/CO₂ flow is mass-balanced against crew respiration and integrated over time into the cabin's own O₂ and CO₂ concentration:

I(depth) = I₀ · e^(−k·X·depth)          (Beer–Lambert self-shading)
μ(I)     = μ_max · I / (I + K_I)         (Monod light-limited growth)
μ_eff    = μ(I_avg) · [CO2]/([CO2]+K_C)  (CO2-limited secondary Monod term)
dX/dt    = (μ_eff − D) · X                (biomass mass balance)
d[O2]/dt = (reactorO2 − crewO2) / V_cabin   (cabin O2 mass balance)
d[CO2]/dt = (crewCO2 − reactorCO2) / V_cabin (cabin CO2 mass balance)

μ_eff is μ(I) averaged over reactor depth and de-rated by CO₂ availability, so raising I₀ helps less once X is high (the culture shades itself) and less still if the CO₂ sparge is starved. The two cabin ODEs above are integrated every frame from the reactor's live O₂/CO₂ output and the crew's respiration load, so the O₂%/CO₂% chart is a genuine running simulation, not a scripted animation — it can settle into a steady state, or drift toward hypoxia (O₂ below ~19.5%) or hypercapnia (CO₂ above ~0.5%) depending on the parameters you choose.

Light intensity I₀ — LED panel output reaching the reactor wall.
Reactor volume — scales the reactor's absolute O₂/CO₂ throughput (L/hr) for a given biomass density.
Dilution rate D — continuous harvest/replenishment; too high washes the culture out (μ < D ⇒ decline), too low lets it self-shade into stagnation.
CO₂ sparge rate — how much CO₂ (from crew respiration + injection) is available to fix; below ~100% it becomes the limiting substrate instead of light.
Crew size — sets O₂ demand (≈0.55 L O₂/hr per astronaut) and CO₂ production (≈0.46 L CO₂/hr per astronaut, respiratory quotient ≈0.83) that the reactor's output is balanced against.

Algae cells (density-shaded) O₂ bubbles rising LED light panel

Cabin O₂ % Cabin CO₂ % ×10