Astronauts need oxygen. Magnets could help

Producing oxygen is tricky under weightless conditions in space. But the addition of a simple magnet can simplify the process of electrolysis, scientists report.

Electrolysis splits water into oxygen and hydrogen using electricity. But under weightless conditions, the bubbles of gas don’t rise to the water’s surface. Instead, they cling to the electrodes submerged in the water, impeding the reaction. Placing a neodymium magnet near an electrode helps dislodge the bubbles, researchers report August 18 in Nature Chemistry.

The electrolysis system aboard the International Space Station spins the water to separate the bubbles. But this method adds bulk and complexity. A streamlined system with magnets could be key for proposed missions to Mars. “As we venture further into space, we really need to have reliable life support systems,” says aerospace engineer Álvaro Romero-Calvo of Georgia Tech in Atlanta.

To test the idea without leaving Earth, Romero-Calvo and colleagues used the Bremen Drop Tower at the Center of Applied Space Technology and Microgravity in Germany. The facility catapults a capsule 120 meters up a tower so that experiments can be performed in near-weightlessness as the capsule falls. In the experiments, bubbles streamed off of the electrodes with magnets, but stuck to those without.

Magnets clear the bubbles in two different ways. The magnetic field makes the water slightly magnetic. This causes the water to be repelled from the magnet and the bubbles to move toward it. Another effect occurs when the water has an acid added to it, as in some electrolysis methods. This produces ions, electrically charged particles, in the fluid. As the ions move through the magnetic field, they experience a sideways force, which sends the fluid and bubbles swirling.

The swirling motion can be used to direct the bubbles to the center of the device, where they could be collected and eventually used to let astronauts breathe easier.