An international research team led by the University of Warwick in the UK has proposed a method for extracting oxygen in a near-zero-gravity environment using neodymium magnets. It could be used for the ISS (International Space Station) and manned exploration of the Moon and Mars. The results of the study are published in npj Microgravity on August 8, 2022.


In your chemistry class, many of you may have done the experiment of electrolyzing water, splitting it into hydrogen and oxygen, and collecting the gas in a test tube. In this case, the air bubbles generated on the surface of the electrode in the water gather at the top of the test tube due to buoyancy, so the liquid and gas can be easily separated.

Even on the ISS, oxygen is produced by electrolysis, but since air bubbles remain in the water under microgravity, it is necessary to forcibly remove the gas. NASA uses centrifuges to separate gas from liquid, but these oxygen generators are large, heavy, and consume a lot of power, so a recent study concluded they were unsuitable for manned Mars exploration. .

Researchers from the University of Warwick (UK), the University of Colorado (Boulder) and the Free University of Berlin (Germany) have demonstrated that magnetism can be used to separate oxygen using a drop tower at the German Center for Applied Space Technology and Microgravity (ZARM). It was demonstrated under gravity environment. "It doesn't require electricity. It doesn't require a centrifuge. In fact, it's a completely passive system," said lead author Álvaro Romero-Calvo of the University of Colorado.

In the experiment, a neodymium magnet was attached to the side of a syringe containing solutions such as ultrapure water and manganese sulfate. Despite its simple structure, the bubbles traced a certain trajectory during their fall due to a phenomenon called magnetic buoyancy.

The results surprised the participants in the experiment. Romero-Calvo believes that magnetic phase separation will be important as a complement to existing methods. In his paper, he also reports on the magnetic interactions between the walls of a syringe, bubbles, and multiple bubbles.

Dr. Katharina Brinkert from the University of Warwick said, "These effects have enormous implications for the development of phase-separation systems, such as for long-term space missions. Even with almost no buoyancy, for example, underwater (photo)electrolyser systems, It suggests that effective oxygen and hydrogen generation is possible in

Professor Hanspeter Schaub of the University of Colorado also said, "We have concrete evidence that this concept works in a zero-gravity space environment." It may be possible to design a system that more efficiently separates the air bubbles from the electrode surface and passively collects them using a magnetic circuit.