It’s about the size of a car battery, but its mission could pave the way for human exploration of Mars. Donald Rapp, a co-investigator for the MOXIE instrument, tells Astrowatch it is the only Mars 2020 Rover instrument “relevant to human exploration.”
MOXIE is the much more manageable acronym for Mars OXygen In-situ resource utilization Experiment. Its mission? To produce oxygen from the red planet’s atmosphere.
Most of Mars’ atmosphere is made up of carbon dioxide. About 96% worth. Oxygen makes up just 0.13%. Nowhere near the 21% in Earth’s atmosphere.
MOXIE’s job is to create oxygen from Mars’ carbon dioxide-rich atmosphere. The research team behind the instrument says the oxygen production rate is about 10 grams per hour. Yeah, that’s not going to be enough for a person – but this instrument is a proof of concept. A MOXIE instrument usable for human missions would need to be about 100 times larger.
The oxygen created by a potential next-gen MOXIE instrument wouldn’t be just for breathing either. Liquid oxygen is a mainstay in rocket fuel.
“When we send humans to Mars, we will want them to return safely, and to do that they need a rocket to lift off the planet. Liquid oxygen propellant is something we could make there and not have to bring with us. One idea would be to bring an empty oxygen tank and fill it up on Mars.”
The impact for creating fuel on Mars is evident. Any mission to Mars is limited by what you can fit atop the rocket getting you there. If astronauts could create most of the fuel there, it would free up space for other vital supplies. The MOXIE team estimates a manned mission to Mars would need anywhere between 33 to 50 tons of fuel. Liquid oxygen makes up more than three-quarters of the propellant needed to reach the red planet.
How does MOXIE work?
You want the simple explanation? The instrument works like a tree. MOXIE ‘breathes’ in carbon dioxide and ‘exhales’ oxygen. Now, let’s dig a little bit into the science behind it.
MOXIE gathers carbon dioxide from Mars’ atmosphere where it compresses and stores it. Then, the instrument electrochemically splits the carbon dioxide molecules into oxygen and carbon. MOXIE analyzes the oxygen to confirm production rate and purity. Here’s a figure showing the process.
One question you might have is how does MOXIE meet planetary protection requirements? NASA is a stickler for keeping bodies as pristine as possible. Because the Solid OXide Electrolyzer (SOXE) within the instrument operates at 800 degrees celsius, exhaust gas cooling is used as a thermal isolation system. The cooled exhausts created during the oxygen creation process are filtered before venting to make sure no unwanted contamination occurs.
MOXIE is still four years away from beginning its journey to the red planet. In the meantime, Rapp tells Astrowatch everything is going well. It’s already passed one review. If it passes the Critical Design Review, the MOXIE team will begin building and testing the flight model.
The Mars 2020 rover (it will be renamed as launch approaches) is expected to launch in July 2020. It will continue the work of NASA’s other Martian rovers. Besides being equipped with better technology, the Mars 2020 rover is also bringing a drill along.
But the rover won’t look all that different than the Curiosity rover. NASA is taking an ‘if it ain’t broke, don’t fix it approach.’ Curiosity is still cruising around the Mars surface 1,500 days after landing. Copying much of the Curiosity design also helps keep costs low. A constant battle NASA always fights. Pushing into the final frontier on a budget.