Ever since humans first ventured beyond Earth, the quest to efficiently and reliably produce oxygen in space has remained one of space exploration’s most persistent hurdles.
A team of scientists and researchers from the Georgia Institute of Technology, the Center of Applied Space Technology and Microgravity (ZARM) at the University of Bremen, and the University of Warwick has found a way to make oxygen production lighter, easier, and more sustainable — using magnetism.
The team described their system and demonstrated its effectiveness in a recent article in Nature Chemistry.
Current life support systems on board the International Space Station require astronauts to spin water in a centrifuge to separate oxygen and hydrogen gas bubbles from the liquid. Although effective, this method is heavy and mechanically complex, making it less than ideal for crewed deep space missions.
“One may think that extracting gas bubbles from liquids in space is as simple as opening a can of soda here on Earth. However, the lack of buoyancy makes the extraction process incredibly difficult, undermining the design and operation of oxygen production systems,” said Álvaro Romero-Calvo, Assistant Professor at Georgia Tech. “In this paper, we demonstrate that two largely unexplored magnetic interactions — diamagnetism and magnetohydrodynamics — provide an exciting pathway to solve this problem and develop alternative oxygen production architectures.”
Astronauts use electricity to split water into hydrogen and oxygen. On Earth, the gases bubble up, away from the electrodes. In the weightlessness of orbit, the bubbles stick to the electrodes and remain suspended in the liquid.
To extract the oxygen, spacecraft life support systems require complex, bulky, and power-hungry centrifuges connected to a water recirculation loop. The entire oxygen generation assembly consumes up to a third of the energy needed for the International Space Station’s life support architecture and requires frequent maintenance.
This makes the system impractical for deep space missions, where every pound of equipment is critical during launch, and any mechanical failure leads to a growing number of spare parts.
In the new study, the team of researchers ditched the centrifuge for magnetic fields. Using commercial-grade magnets, they developed a passive phase separation system that pushes the bubbles away from the electrodes and collects them at designated spots.
To push the bubbles away, they first took advantage of how water naturally responds to magnets in microgravity, guiding gas bubbles toward collection points using a process called diamagnetism.
Then their system capitalized on the interaction between magnetic fields and electric currents generated by electrolysis, which creates a spinning motion.
This phenomenon, known as magnetohydrodynamics (MHD), is used to separate gas bubbles from water through centrifugal effects in the same way mechanical rotation does.
The approach was first developed in 2022 by Romero-Calvo as part of his Ph.D. thesis at the University of Colorado Boulder and then proved feasible under his Phase I grant from the NASA Innovative Advanced Concepts (NIAC) program.
His Low-Gravity Science and Technology lab at Georgia Tech has recently been awarded a Phase II NIAC to develop a MHD oxygen production architecture for splitting water into oxygen and hydrogen for a Mars transit mission.
Prof. Katharina Brinkert’s group at ZARM carried out the electrochemical analysis and microgravity proof-of-concept tests of the technology at ZARM’s drop tower in Bremen, Germany. The ZARM drop tower is one of the tallest and best-known drop tower facilities in Europe, measuring 146 meters high, which results in 9.3 seconds of microgravity experiment time.
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