A solid-oxide cell can pull oxygen out of carbon dioxide. The reaction is CO2 -> CO + 1/2 O2. With integer molar masses, 44 g of CO2 yields 16 g of O2 and leaves 28 g of CO. MOXIE, the oxygen experiment on Perseverance, flew that reaction. The 2022 report of the early runs uses a reference rate of 6 g/h. [1]

The lower atmosphere is 95.1% carbon dioxide by volume in the fact-sheet compilation, at a datum pressure of 6.36 mbar at the mean radius. [2] Free oxygen in that compilation is only 0.16%. The cell does not invent an oxygen atom. It separates one that was already bound in CO2.

Screen

Type a crew size. The oxygen mass is that count times the life-support rate, 0.816 kg per person per day, times a margin you type. A blank margin is 1, and the margin is not a number from the MOXIE papers. Carbon dioxide is that oxygen mass times 44/16. Hours at 6 g/h and at 12 g/h say how long one instrument at those rates would need for that day's oxygen. One person at the peak rate is 68 hours. The build checks that. The form does not add compressors, heaters, dryers, or tanks.

Class A instrument

Screening sheet. Not for flight, medicine, or operations. CO2 to CO + 1/2 O2. Not a plant design.

44 g of CO2 yields 16 g of O2. Hours are that oxygen mass, in grams, divided by 6 g/h or 12 g/h. One person at 12 g/h is 68 hours. The margin is yours.

What was demonstrated

The demonstrated record is a peak of 12 g/h and 122 g in total, across 16 runs ending 7 August 2023. Those figures belong to the Perseverance instrument. They are not a crew plant. [3]

A crew plant cited by the MOXIE team is on the order of 2 to 3 kg/h. [1] This page does not size that plant. The oxygen was a measured product of a technology demonstration. This page does not say it was stored, breathed, or loaded into an engine. Breathing limits live on Cabin gas. The per-person oxygen rate lives on Crew budget. Ambient pressure lives on Pressure and the areoid.

See also

References

  1. Hoffman, Hecht, Rapp et al., Science Advances 8 (2022), doi 10.1126/sciadv.abp8636 https://www.science.org/doi/10.1126/sciadv.abp8636
  2. NASA Goddard Space Flight Center. Mars Fact Sheet. Composition and datum pressure. Updated 19 May 2025. https://nssdc.gsfc.nasa.gov/planetary/factsheet/marsfact.html
  3. NASA. NASA's oxygen-generating experiment MOXIE completes Mars mission. 6 September 2023. 122 g total, 12 g/h peak, 16 runs, final run 7 August 2023. https://www.nasa.gov/solar-system/nasas-oxygen-generating-experiment-moxie-completes-mars-mission/

Categories

Engineering