How does an Earth terrarium ecosystem respond to a lunar-length light cycle?
A lunar day lasts roughly 29.5 Earth days — about 14.75 days of continuous sunlight followed by 14.75 days of darkness. This experiment scales that ratio down to a manageable 48-hour light / 48-hour dark cycle and measures how a sealed terrarium ecosystem responds compared to a normal 16h/8h control period.
The goal is to understand whether a closed-loop ecosystem built with common temperate species can tolerate extended photoperiods without collapsing — and what the early warning signs look like if it can't.
Extending the light/dark cycle from 16h/8h to 48h/48h will measurably alter CO2 drawdown rates, humidity swing amplitude, and observable plant health — but the ecosystem will remain viable if returned to normal light before CO2 exceeds safety thresholds.
Photoperiod length — switching from a 16-hour on / 8-hour off cycle (control) to a 48-hour on / 48-hour off cycle (treatment).
CO2 concentration (ppm), temperature, relative humidity, light-phase CO2 drawdown rate (ppm/hr), dark-phase CO2 rise rate (ppm/hr), and plant health score (1–5 visual scale).
Sealed jar (no gas exchange), constant ambient room temperature (~20–22 °C), same grow light and position throughout, no feeding or watering during test phases.
Initial observation period under 9h and then 12h light cycles. CO2 climbed steadily to ~4,700 ppm due to heavy microbial respiration from decomposing organic matter (lichen-covered stick and leaf litter), revealing that the system was locked in a high-CO2 equilibrium.
Removed the lichen-covered stick and leaf litter to reduce microbial CO2 production, and extended the grow light from 12 to 16 hours per day. CO2 dropped from ~4,700 ppm to the ~1,800 ppm range. Waiting for daily averages to stabilize within 50 ppm day-over-day before proceeding.
Continue 16h/8h cycle once CO2 is stable. Record full day/night CO2 curves, drawdown and rise rates, humidity swings, and a plant health score. This establishes the baseline that treatment data will be compared against.
Switch to 48h light / 48h dark. Monitor for changes in CO2 drawdown efficiency, humidity extremes, and any visible plant stress. Safety abort if CO2 exceeds 5,000 ppm. This is the core experimental phase.
Return to 16h/8h cycle. Measure how quickly (or whether) CO2 curves, humidity, and plant health return to baseline values.
Compare control vs. treatment vs. recovery data. Calculate statistical differences in drawdown rates, humidity amplitude, and overall ecosystem resilience.
How fast CO2 drops during light hours (ppm/hr) — indicates photosynthetic activity
How fast CO2 climbs during dark hours (ppm/hr) — indicates respiration load
Difference between daily max and min humidity — wider swings may signal stress
Internal temp tracked continuously — held constant by ambient room conditions
Visual 1–5 scale assessed at each phase transition — leaf color, turgor, growth
If CO2 exceeds 5,000 ppm and is climbing > 50 ppm/hr, lights turn on and treatment ends
A sealed glass jar containing moss, small plants, isopods, and springtails — monitored 24/7 by an ESP32 microcontroller with an SCD41 environmental sensor logging CO2, temperature, and humidity every 30 seconds.