A potentially better way to make oxygen for astronauts in space using
magnetism has been proposed by an international team of scientists,
including a University of Warwick chemist.
The conclusion is from new research on magnetic phase separation in
microgravity published in npj Microgravity by researchers from the
University of Warwick in the United Kingdom, University of Colorado Boulder
and Freie Universität Berlin in Germany.
Keeping astronauts breathing aboard the International Space Station and
other space vehicles is a complicated and costly process. As humans plan
future missions to the Moon or Mars better technology will be needed.
Lead author Álvaro Romero-Calvo, a recent Ph.D. graduate from the University
of Colorado Boulder, says that "on the International Space Station, oxygen
is generated using an electrolytic cell that splits water into hydrogen and
oxygen, but then you have to get those gasses out of the system. A
relatively recent analysis from a researcher at NASA Ames concluded that
adapting the same architecture on a trip to Mars would have such significant
mass and reliability penalties that it wouldn't make any sense to use."
Dr. Katharina Brinkert of the University of Warwick Department of Chemistry
and Center for Applied Space Technology and Microgravity (ZARM) in Germany
says that "efficient phase separation in reduced gravitational environments
is an obstacle for human space exploration and known since the first flights
to space in the 1960s. This phenomenon is a particular challenge for the
life support system onboard spacecraft and the International Space Station
(ISS) as oxygen for the crew is produced in water electrolyzer systems and
requires separation from the electrode and liquid electrolyte."
The underlying issue is buoyancy.
Imagine a glass of fizzy soda. On Earth, the bubbles of CO2 quickly float to
the top, but in the absence of gravity, those bubbles have nowhere to go.
They instead stay suspended in the liquid.
NASA currently uses centrifuges to force the gasses out, but those machines
are large and require significant mass, power, and maintenance. Meanwhile,
the team has conducted experiments demonstrating magnets could achieve the
same results in some cases.
Although diamagnetic forces are well known and understood, their use by
engineers in space applications have not been fully explored because gravity
makes the technology difficult to demonstrate on Earth.
Enter the Center for Applied Space Technology and Microgravity (ZARM) in
Germany. There, Brinkert, who has ongoing research funded by the German
Aerospace Center (DLR), led the team in successful experimental tests at a
special drop tower facility that simulates microgravity conditions.
Here, the groups have developed a procedure to detach gas bubbles from
electrode surfaces in microgravity environments generated for 9.2s at the
Bremen Drop Tower. This study demonstrates for the first time gas bubbles
can be 'attracted to' and 'repelled from' a simple neodymium magnet in
microgravity by immersing it in different types of aqueous solution.
The research could open up new avenues for scientists and engineers
developing oxygen systems as well as other space research involving
liquid-to-gas phase changes.
Dr. Brinkert says that "these effects have tremendous consequences for the
further development of phase separation systems, such as for long-term space
missions, suggesting that efficient oxygen and, for example, hydrogen
production in water (photo-)electrolyzer systems can be achieved even in the
near-absence of the buoyant-force."
Professor Hanspeter Schaub of University of Colorado Boulder says that
"after years of analytical and computational research, being able to use
this amazing drop tower in Germany provided concrete proof that this concept
will function in the zero-g space environment."
Reference:
Álvaro Romero-Calvo et al, Magnetic phase separation in microgravity, npj
Microgravity (2022).
DOI: 10.1038/s41526-022-00212-9
Tags:
Space & Astrophysics