>is it more effective to scrub the CO2 or just to increase the partial oxygen pressure? In all nuclear submarines (which stay submerged for months at a time) a

>is it more effective to scrub the CO2 or just to increase the partial oxygen pressure? In all nuclear submarines (which stay submerged for months at a time) and spacecraft I know about, designers have chosen to scrub CO2. I think they have no choice but to scrub CO2 because CO2 has important effects on the body (e.g., increasing acidity of the blood) that cannot be counteracted by any concentration of O2. On subs, I think they react the CO2 with calcium hydroxide. On spacecraft, NASA has used lithium hydroxide (because lithium weighs less than calcium). The hydroxide gets used up during the mission. then NASA switched to some complicated system that does not use up a reagent.