Mars Oxygen ISRU Experiment
The Mars Oxygen In-Situ Resource Utilization Experiment (MOXIE)[1] was a technology demonstration on the NASA Mars 2020 rover Perseverance investigating the production of oxygen on Mars.[2] On April 20, 2021, MOXIE produced oxygen from carbon dioxide in the Martian atmosphere by using solid oxide electrolysis. This was the first experimental extraction of a natural resource from another planet for human use.[1][3] The technology may be scaled up for use in a human mission to the planet to provide breathable oxygen, oxidizer, and propellant; water may also be produced by combining the produced oxygen with hydrogen.[4]
"MOXIE" redirects here. For other uses, see Moxie (disambiguation).Operator
NASA/Caltech/Jet Propulsion Laboratory
OxEon Energy
ISRU (in situ resource utilization) experimental technology
Oxygen production
20 April 2021
3 August 2023
15 kg (33 lb)
24 × 24 × 31 cm
300 W
July 30, 2020
Atlas V 541
Cape Canaveral SLC-41
The experiment was a collaboration between the Massachusetts Institute of Technology, the Haystack Observatory, the NASA/Caltech Jet Propulsion Laboratory, with OxEon Energy.
Objective[edit]
MOXIE's objective was to produce oxygen of at least 98% purity at a rate of 6–10 grams per hour (0.21–0.35 oz/h) and to do this at least ten times, so the device can be tested in a range of times of the day, including at night, and in most environmental conditions, including during a dust storm.[1]
Principle[edit]
MOXIE acquires, compresses, and heats Martian atmospheric gases using a HEPA filter, scroll compressor, and heaters alongside insulation,[1] then splits the carbon dioxide (CO
2) molecules into oxygen (O) and carbon monoxide (CO) using solid oxide electrolysis, where the O atoms combine to form gaseous oxygen (O
2).[12]
The conversion process requires a temperature of approximately 800 °C (1,470 °F).[4] A solid oxide electrolysis cell works on the principle that, at elevated temperatures,[12] certain ceramic oxides, such as yttria-stabilized zirconia (YSZ) and doped ceria, become oxide ion (O2–) conductors. A thin nonporous disk of YSZ (solid electrolyte) is sandwiched between two porous electrodes. CO
2 diffuses through the porous electrode (cathode) and reaches the vicinity of the electrode-electrolyte boundary. Through a combination of thermal dissociation and electrocatalysis, an oxygen atom is liberated from the CO
2 molecule and picks up two electrons from the cathode to become an oxide ion (O2–). Via oxygen ion vacancies in the crystal lattice of the electrolyte, the oxygen ion is transported to the electrolyte–anode interface due to the applied DC potential. At this interface, the oxygen ion transfers its charge to the anode, combines with another oxygen atom to form oxygen (O
2), and diffuses out of the anode.[1]
The net reaction was thus 2 CO
2 2 CO + O
2. Inert gases such as nitrogen gas (N
2) and argon (Ar) are not separated from the feed, but returned to the atmosphere with the carbon monoxide (CO) and unused CO
2.[1]
Implications[edit]
NASA states that if MOXIE worked efficiently, they could land an approximately 200-times larger, MOXIE-based instrument on the planet, along with a power plant capable of generating 25–30 kilowatts (34–40 hp).[1] Over the course of approximately one Earth year, this system would produce oxygen at a rate of at least 2 kilograms per hour (4.4 lb/h)[1] in support of a human mission sometime in the 2030s.[17][18] The stored oxygen could be used for life support, but the primary need is for an oxidizer for a Mars ascent vehicle.[19][20] It was projected for example, in a mission of four astronauts on Martian surface for a year, only about 1 metric ton of oxygen would be used for life support for the entire year, compared to about 25 metric tons of oxygen for propulsion off the surface of Mars for the return mission.[13] The CO, a byproduct of the reaction, may be collected and used as a low-grade fuel[21] or reacted with water to form methane (CH
4) for use as a primary fuel.[22][23] As an alternative use, an oxygen generation system could fill a small oxygen tank as fuel-oxidiser to support a sample return mission.[24] The oxygen could also be combined with hydrogen to form water.[4]
Data from NASA (MARS 2020 Mission Perseverance Rover),[9] Ceramatec and OxEon Energy,[25] NASA Jet Propulsion Laboratory.[26]
MOXIE: Operational Design Drive (SOXE):
MOXIE: Materials Design Drivers:
MOXIE: Cell design:
Connecting cells:
MOXIE: Gas delivery system (scroll compressor):
MOXIE: Targets: