This lesson was originally published before deployment of the MOXIE experiment on Mars. In this activity, students will: Design an air-recycling system capable of capturing simulated carbon dioxide so astronauts can breath safely while on the International Space Station or a future Mars mission. Build and test a filter capable of "scrubbing" carbon dioxide out of the atmosphere while allowing air to flow. Calculate the efficacy of the filter. Use stoichiometry to determine how many filters are