Implementation of Lithium Hydroxide as a Dual CO2/H2O Scrubber for a Rodent Research Life Support System



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48th International Conference on Environmental Systems


AEM-E (Animal Enclosure Module – Environmental Control) was developed as a middeck locker payload to provide life support for rodent research in space. The AEM-E design has recently been upgraded to double its original rated capacity, now supporting 40 mice or 12 rats over a 10-day mission while maintaining its original single-locker form factor. A key enabling design modification in achieving this considerable performance increase was to combine the relative humidity (rH) and carbon dioxide (CO2) scrubber systems using a single lithium hydroxide (LiOH) scrubbing architecture. LiOH is a well-known CO2 scrubbing material with life support applications dating back to the first manned space missions. LiOH reacts with cabin atmospheres via hydration (reversibly producing LiOH·H2O) and carbonation (irreversibly producing Li2CO3). Despite a rich background of research relating to LiOH carbonation, relatively little research has been reported on LiOH hydration with most studies only focusing on its role as a catalyzing reaction for carbonation. Compared to other desiccants such as silicon dioxide (SiO2), LiOH offers superior volume and mass efficiency. Based on this, LiOH was selected as the primary humidity and CO2 scrubbing material for the updated AEM-E design, which we believe to be the first reported spacecraft life support application of LiOH where humidity control is a primary function. This paper discusses the empirical formulation of a dual CO2/H2O absorption model for LiOH and its integration into a multi-scenario mission simulation alongside other AEM E components and rodent metabolic models. Underactuated single-input multiple-output (SIMO) control is a key implementation challenge of dual CO2/rH control with LiOH and requires a specific metabolic envelope of CO2 and H2O output rates to function acceptably. However, based on the work presented herein, the dual control scheme is expected to satisfy AEM-E’s operational requirements.


Jonathan Anthony, University of Colorado Boulder
Alexander Hoehn, University of Colorado Boulder
Tobias Niederwieser, University of Colorado Boulder
Louis Stodieck, University of Colorado Boulder
Stuart Tozer, University of Colorado Boulder
ICES302: Physio-chemical Life Support- Air Revitalization Systems -Technology and Process Development
The 48th International Conference on Environmental Systems was held in Albuquerque, New Mexico, USA on 08 July 2018 through 12 July 2018.


Lithium Hydroxide, Carbon Dioxide Removal, Humidity Control, Rodent Research, Spacecraft Life Support