With the Artemis program, NASA aims to regain the Moon by sending the first woman and the first black person to the natural satellite, and establishing the long-term human presence on it starting from 2030. All this, explains NASA, “[…] to make new scientific discoveries, obtain economic benefits and to inspire a new generation of explorers: the Artemide generation ”. But also for another reason. To prepare for the next giant leap of humanity: sending the human being to Mars. Science fiction? Not at all, so much so that the US space agency is already moving forward to solve one of the problems that astronauts will have to face when this happens: the absence of oxygen on the planet.
One of the experiments that NASA is conducting in this regard is called Moxie, an acronym for Mars Oxygen In-Situ Resource Utilization Experiment. Its purpose? Demonstrate the functioning of a technology capable of replicating on Mars what plants, green algae and cyanobacteria do on Earth: producing oxygen from CO2 – gas that makes up 96 percent of the atmosphere of the Red Planet. Oxygen to be used for breathing by astronauts but also as a propellant to power vehicles for returning to Earth.
Located on the right front side of the Perseverance rover, Moxie has been producing oxygen since 2021 – the year NASA’s six-wheeled robot landed on the Martian surface – using an instrumental apparatus measuring 24x24x31 centimeters and weighing about 17 kilos, plus minus the dimensions. of a car battery, whose job is to capture Martian CO2 and break it, thus producing carbon monoxide and the indispensable diatomic molecule.
The figure below shows in detail the operation of the experiment, managed by the Massachusetts Institute of Technology (MIT) together with other international partners. At first, a CO2 Acquisition and Compression System (Cac) sucks the Martian atmosphere from outside the rover through a filter, which cleans it of contaminants, and pressurizes it to approximately one atmosphere. Next, the pressurized CO2 is sent to an electrolytic cell called Soxe (Solid Oxide Electrolyzer), a sort of battery that electrochemically splits carbon dioxide, producing oxygen ions at the cathode and carbon monoxide at the anode. At this point, the oxygen ions are isolated and recombined to form molecular oxygen, which the instrument finally releases into the atmosphere after measuring its quantity and purity.
The one just described is a conversion process that requires operating temperatures of around 800 degrees Celsius, which is why the instrument is made of insulating and heat-resistant materials. These include 3D printed nickel alloy parts, which heat and cool the gases passing through them, an airgel that helps retain heat, and a thin gold coating that prevents the exiting heat from radiating outward and damaging. Perseverance.
The current version of the experiment, which envisages an instrumental unit of such size as to allow it to be installed on board the rover, has made it possible to produce oxygen in a variety of conditions to date. Each experimental test conducted was in fact programmed for a different hour of the day or night and in different seasons, the researchers explain, to verify whether the instrument could adapt to changes in the planet’s atmospheric conditions.
In each of the seven experimental trials conducted in 2021 – the results of which are reported in a study published yesterday in Science Advances – the tool managed to produce six grams of oxygen per hour – almost the production speed of a tree on Earth – taking a few hours each time to warm up, then another hour to produce oxygen before shutting down again.
Despite the necessary compromises in the current design, the instrument has therefore been shown to be able to reliably and efficiently convert Martian CO2 into pure oxygen, becoming the first instrument to produce the molecule on another world.
“The only thing we haven’t demonstrated is how it works at sunrise or sunset, when the planet’s temperature changes substantially,” he points out Michael Hechtresearcher at MIT, principal investigator of the tool and co-author of the publication. “But we have an ace up our sleeve that will allow us to do it: laboratory tests. Once done, we will get the last milestone to show that we can produce oxygen at any time ».
The production of oxygen by Moxie on Mars represents the first demonstration of the possibility of “use in situ of space resources “(in-situ resource utilizationIrsu, in English): a concept that is based on the idea of collecting and using the materials of a planet (in this case carbon dioxide on Mars) to create resources (such as oxygen) that would otherwise have to be transported by the Land.
“This is the first demonstration of the effective use of the resources present on the surface of another planetary body and their chemical transformation into something that would be useful for a human mission. And in this sense it is historical ”, says the first author of the study e deputy principal investigator of the instrument, Jeffrey Hoffman.
The next step will be to increase the instrument’s production capacity, the researchers add, particularly in the Martian spring, when atmospheric density and carbon dioxide levels are high. “The next experimental test will take place during the season with the highest atmospheric density of the year, during which we want to produce as much oxygen as possible,” says Hecht. “To do this, we will bring the instrument to its maximum potential and make it work for as long as possible”. This is a further test that will represent a test bench to monitor the instrument for any signs of wear. In fact, Moxie cannot run continuously as a larger instrument unit could. Rather, the instrument will need to be turned on and off with each experiment, a thermal stress that over time can cause damage to the system. If despite these on-and-off cycles Moxie continues to function properly, this would suggest that a larger version of the tool, designed to run continuously, could remain operational for thousands of hours, the team points out.
The researchers predict that a large-scale version of Moxie could be sent to Mars before a human mission, to continuously produce oxygen at the rate of several hundred trees, allowing both to sustain the presence of the human being upon his arrival on the planet and to power the rockets for the return of the astronauts to Earth.
To know more:
- Read on Science Advances the article “Mars Oxygen ISRU Experiment (MOXIE) – Preparing for human Mars exploration” by Jeffrey A. Hoffman1, Michael H. Hecht, Donald Rapp, Joseph J. Hartvigsen, Jason G. SooHoo, Asad M. Aboobaker, John B. McClean, Andrew M. Liu, Eric D. Hinterman, Maya Nasr, Shravan Hariharan, Kyle J. Horn, Forrest E. Meyen, Harald Okkels, Parker Steen, Singaravelu Elangovan, Christopher R. Graves, Piyush Khopkar, Morten B. Madsen, Gerald E. Voecks, Peter H. Smith, Theis L. Skafte, Koorosh R. Araghi, and David J. Eisenman
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