## 3 Results
### The MOXIE Project (2014-2023)  
Prior to about 2014, technical advances in Mars ISRU were sporadic and intermittent, and always at low TRL. In late 2013, an unprecedented announcement of opportunity (AO) suddenly appeared for proposals for a (then) $30 million ISRU demonstration on Mars. This was a very bold, imaginative venture. It involved building an engineering payload and flying it \"piggyback\" on a Mars Science Rover, utilizing onboard electric power storage. It demonstrated Mars ISRU at a level not previously achieved. There was no solid basis for definition of requirements and budget because NASA was entering unchartered territory. The massive increase in Mars ISRU funding was unprecedented. How this project fitted into a long-term plan for Mars ISRU was not defined. We are not certain of the final runout budget for MOXIE. Our rough guess is that the total project runout cost was about USD 55 million, of which the amount spent on development of the SOEC stack was about USD 6 million. Another few million likely went into developing the mechanical compressor. The remaining roughly USD 45 million went into engineering the rest of the system to support design, development, test, and operation of a highly compressed system that was mounted on the Perseverance Rover for Mars. This AO was a stroke of genius because it saved all the costs of a mission to Mars by \"piggybacking\" a Mars ISRU system on a Rover, thus avoiding the need for a dedicated ISRU mission. It was also highly innovative because it involved putting an exploration device on a science rover and the several directorates of NASA fully cooperated. It changed Mars ISRU technology from a concept to a reality. A team from JPL and Massachusetts Institute of Technology (MIT) and a small contractor (Ceramatec, later changed to OxEon) wrote the winning proposal in response to the AO, and thus the MOXIE Project began in late 2014. The project ran until its close 30 September 2023.  
MOXIE plans and results were documented in four publications [38; 39; 40; 41]. The programmatic achievements of MOXIE included:  
* Demonstrated production of oxygen on Mars up to \(\sim\)12 g/h;
* Produced oxygen purity of \(\sim\)100% with anode pressure \(>\) cathode pressure;
* Produced oxygen at low Mars temperature in early hours after midnight and warm Mars temperature in early afternoon in all seasons;
* Demonstrated low rate of degradation through more than 20 thermal cycles;
* Demonstrated a mechanical compressor to acquire Mars atmospheric gas.  
The technical achievements of MOXIE included:
* Demonstrated sealed stacks of cells that could electrolyze essentially pure CO\({}_{2}\) without oxidation of the electrodes or reduction of product CO--a new first;* Demonstrated that the Flight Model MOXIE on Mars was essentially identical in performance to the Engineering Model MOXIE in Lab. This was a major observation that showed that operation on Mars could be replicated in the lab on Earth;
* Explored the relationship between stack voltage and current (oxygen production rate was explored extensively);
* The intrinsic area-specific cell resistance (iASR) was evaluated over a wide range of operating settings and iASR was found to be small enough to allow efficient full-scale operation with such stacks;
* By comparing iASR from Mars run to Mars run, it was demonstrated that degradation due to thermal cycling was well within acceptable limits;
* Carried out extensive testing and analysis of filters for Martian dust and determined that dust removal in a full-scale Mars ISRU could be achieved with a reasonably sized filter system.