Making oxygen on Mars: Rover tests technology to make Red Planet breathable NASA rover turns carbon dioxide into oxygen on Mars Tags: And this week, Perseverance was successful in one major test: Creating oxygen! Mars’ atmosphere is mostly carbon dioxide, but that doesn’t cut it -- humans need oxygen to breathe, and also for rocket fuel to return home. So, when Perseverance landed on Mars earlier this year, it brought with it a toaster-size instrument called the Mars Oxygen In-Situ Resource Utilization Experiment -- or “MOXIE” for short. Here’s how it works: Carbon dioxide is made up of one carbon atom and two oxygen atoms. MOXIE separates the two oxygen atoms from that carbon atom and, voila, you have oxygen!