A Change of Air on Mars

NASA’s Perseverance rover continues to break ground on Mars since its landing on the Red Planet in February.

In an experiment conducted on Mars, part of the Red Planet’s thin and toxic atmosphere was converted to oxygen. MOXIE (Mars Oxygen On-Site Resource Utilization Experiment) landed on Mars on February 18 with the Perseverance rover. This experimental device, about the size of a shoebox, disintegrated carbon dioxide molecules into its components to produce about 5 grams of oxygen, which is equivalent to about 10 minutes of breathable air. This is also an amount enough to make minute amounts of rocket fuel.

The atmosphere on Mars is predominantly made up of carbon dioxide. It is also 100 times thinner than Earth’s atmosphere, which is why humans cannot breathe it in order to survive, despite its composition similar to Earth’s air. If we are to send an exploration team to Mars, they will need to take their own oxygen with them.

Oxygen is also a very important component of most rocket fuels, so if these astronauts would like to return home, they will have to carry heavy fuel tanks along throughout their entire journey. NASA estimates that it will take about 25 tons of oxygen to return four astronauts from Mars back home. Because carrying anything to Mars is extremely expensive, and because the capacity of rockets is limited, every single gram counts.

MOXIE was the first step towards solving these two problems by producing oxygen on Mars; it absorbs carbon dioxide from the Martian atmosphere and heats it up to temperatures of around 800°C, thus allowing oxygen atoms to detach from carbon dioxide molecules. After the oxygen in the air is isolated by a hot, charged ceramic component, oxygen ions merge into O₂ molecules. Carbon monoxide, on the other hand, is sent back into the atmosphere in a harmless way.

When the purity of the oxygen MOXIE produced was analysed, the resulting products were almost 100% pure oxygen. This prototype device can produce about 10 grams of oxygen per hour at full power. Powered by Perseverance, MOXIE will be able to operate for approximately one Mars day at a time. MOXIE cannot operate continuously because Perseverance has to divert its power back to other devices to continue its mission of looking for signs of past life on Mars. MOXIE will have the chance to do its mission at least nine times more in the next Mars year (about two Earth years).

In the future, a larger and improved version of it may run continuously for 26 months, before the astronauts arrive.