Bremen, Germany, is not known for its skyscrapers. The tallest structure in the city is a 236 m telecommunications tower. The second tallest, the 146 m Bremen Drop Tower (shown in figure 1 ), is devoted to scientific research. It’s the main facility of the Center of Applied Space Technology and Microgravity (ZARM) at the University of Bremen, and it houses an unobstructed vertical tube that allows researchers to see how experiments behave in free fall.
Diverse physical phenomena are studied at the Bremen Drop Tower, including turbulent flow and matter-wave interferometry. But the center’s codirector Katharina Brinkert is an electrochemist with an interest in developing systems to produce oxygen and fuels, such as hydrogen, for space exploration missions.
On Earth, the electrochemical splitting of water into its component elements is a familiar and well-studied reaction. Hydrogen accumulates at the cathode, oxygen at the anode, and both gases bubble up through the liquid and can be collected at the surface. But without gravity, there is no “bubbling up.” Some other forces are needed to pull the gas bubbles away from the electrodes.
Now Brinkert has teamed up with ZARM research associate Ömer Akay, Georgia Tech assistant professor in aerospace engineering Álvaro Romero-Calvo, and others to show that magnetic fields might do the job in not just one but two ways. 1 In their proof-of-principle experiments at the Bremen Drop Tower, the researchers demonstrated two fundamentally different uses of magnetic forces to facilitate water electrolysis in microgravity. In one, the forces act on the water molecules themselves; in the other, they act on ions in solution.
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