Mars Oxygen ISRU Experiment


Mars Oxygen ISRU Experiment is an exploration technology experiment that will produce a small amount of pure oxygen from Martian atmospheric carbon dioxide in a process called solid oxide electrolysis.
MOXIE is a 1% scale model aboard the Perseverance rover, as part of the Mars 2020 mission. The Principal Investigator of the MOXIE instrument is Michael Hecht from the Massachusetts Institute of Technology. The Niels Bohr Institute at the University of Copenhagen is collaborating with MIT to develop this prototype. If successful, the technology can be scaled up as a means of producing oxygen for propellant oxidant in a Mars Ascent Vehicle for a sample return.

Objective

The main objective of this experiment is to produce molecular oxygen from the atmospheric carbon dioxide which makes up 96% of the Martian atmosphere. Scientists will record the efficiency of the O2 production rate, and the resulting oxygen and carbon monoxide will be vented out after measurements are done.
To achieve this objective, the MOXIE instrument has a goal of producing 22 g of oxygen per hour with >99.6% purity for 50 sols.
NASA officials stated that if MOXIE worked efficiently, they could land a 100 times larger MOXIE-based instrument on Mars, along with a radioisotope thermoelectric generator. Over the course of some years the generator would power the system, which would produce up to two kilograms of oxygen per hour, and fill an oxygen reservoir that could be used for a sample return mission, or for when NASA astronauts could arrive sometime in the 2030s. The stored oxygen could be used for life support, and can also be used as rocket propellant oxidizer to power their return trip to Earth. High purity is crucial as future astronauts will breathe it. Nitrogen| and Ar are not separated from feed, but vented with carbon monoxide. The CO, a byproduct of the reaction, may also be collected and used as propellant or converted to methane for use as propellant.

Development

MOXIEUnits/performance
PurposeTest production
from atmospheric
Mass
Power300 W
Dimensions23.9 × 23.9 × 30.9 cm
production rate10-22 grams/hr

The MOXIE experiment follows up on an earlier experiment, Mars ISPP Precursor, which was designed and built to fly on the Mars Surveyor 2001 Lander mission. MIP was intended to demonstrate In-Situ Propellant Production at a laboratory-scale using electrolysis of carbon dioxide to produce oxygen on Mars. The MIP experiment was postponed when the 2001 Lander mission was cancelled following the failure of the 1998 Mars Polar Lander.
The Principal Investigator is Michael Hecht and Deputy Principal Investigator Jeffery Hoffman from the Massachusetts Institute of Technology. Collaborators include the University of Copenhagen, Arizona State University, Imperial College of Science, International Program Manager Jeff Mellstrom from NASA Jet Propulsion Laboratory, Ceramatec, Inc., Air Squared Space Exploration Instruments LLC., and the Technical University of Denmark.

Principle

MOXIE collects from the Martian atmosphere, then electrochemically splits the molecules into and CO. A solid oxide electrolysis cell works on the principle that, at elevated temperatures, certain ceramic oxides, such as yttria-stabilized zirconia and doped ceria, become oxide ion conductors. A thin nonporous disk of YSZ is sandwiched between two porous electrodes. For oxygen generation from carbon dioxide, CO2 diffuses through the porous electrode and reaches the vicinity of the electrode-electrolyte boundary. Through a combination of thermal dissociation and electrocatalysis, an oxygen atom is liberated from the molecule and picks up two electrons from the cathode to become an oxide ion. 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, and diffuses out of the anode.
The net reaction is thus +