Cabin CO2 Scrubber Compliance Monitor (2D)

Compliance Status

PASS — within SMAC limit

Cabin CO2

0 ppm

Time in compliance

100.0%

Mission elapsed

0h 00m

Active bed load

Crew & Metabolic Load

Crew size 4

2-Bed Molecular Sieve Scrubber

Scrubber efficiency 1.60 kg/hr

Bed cycle time 5.5 min

Contamination

Leak / off-gas rate 0%

How it works

Cabin CO2 partial pressure is a mole balance between crew metabolic production (boosted by any leak/off-gas source) and scrubber removal:

dn_CO2/dt = N·ṁ_person·(1+leak) − R_scrub(t)
ppm(t)    = (n_CO2 / n_total) × 10^6

Each crew member produces roughly 1.04 kg CO2/day at rest; n_total is fixed by cabin volume and pressure via the ideal gas law, n = PV/RT.

The scrubber alternates two zeolite beds — one adsorbing CO2 from the air while the other desorbs (vents to vacuum and regenerates), swapping every cycle time. Removal from the active bed is capped by its efficiency rating and falls off as that bed's load approaches its fixed physical capacity:

R_scrub = R_max · sqrt(max(0, 1 − load/bedCapacity))

Cycle too long and the active bed saturates mid-cycle, removal collapses, and CO2 rises past the SMAC (Spacecraft Maximum Allowable Concentration) limit; cycle too short and the desorbing bed never fully regenerates, quietly shrinking its usable capacity on the next swap. NASA's operational SMAC bands used here: <5,000 ppm nominal, 5,000–7,000 ppm caution, >7,000 ppm exceedance requiring corrective action.

Nominal (<5,000 ppm) Caution (5,000–7,000) Exceedance (>7,000) Bed A / Bed B

Cabin CO2 Scrubber Compliance Monitor — 2D Trend View