Particle physics experiments

Microgravity experiments could help future space missions find water

New research on generating oxygen from water found on the surfaces of other planets could help support future long-term missions to the Moon and Mars.

Researchers from the University of Glasgow and their colleagues made a series of grueling microgravity flights to study how the different gravitational pull of other planets might affect the electrolysis process.

Electrolysis uses an electric current, passed through two electrodes, to split water into its constituent gases – hydrogen and oxygen. Oxygen is vital for space missions to allow astronauts to breathe and refuel their rockets.

Currently, space missions carry all the oxygen they need in bulky tanks. However, as plans to establish permanent bases on the Moon and Mars gather pace, space scientists are proposing to find sources of oxygen instead in the form of ice, which may be present on both. planetary surfaces.

Electrolysis of melted ice could free missions from the need to carry all their own oxygen and help proposed long-term habitations like NASA’s Artemis moon station become self-sufficient.

Although the process of electrolysis on Earth is well understood, much less is known about how it might work in the low-gravity environments of Mars, where the pull of gravity is one-third that of Earth. and the Moon, where it is just one-sixth.

In a new paper published in Nature Communications, the research team, led by Dr. Bethany Lomax, describes how they set out to find answers to these questions for the first time.

To do this, they designed and built an experiment to take into account the microgravity environments created during parabolic flights. In these flights, aircraft create brief periods of weightlessness by flying in alternating upward and downward arcs.

On board an Air Zero G Airbus A310 piloted from an airport in Germany by the European Space Agency and Novespace, the researchers deployed four electrolysis cells integrated into a small centrifuge.

As the plane passed through microgravity, they were able to recreate the Moon’s lower gravitational conditions by spinning the centrifuge at different speeds. While doing this in three separate flights of 31 parabolic arcs each, they measured the oxygen bubbles produced at the electrodes of each cell.

Their results suggest that the electrochemical cells would produce 11% less oxygen in low gravity than on Earth if more power was not supplied to compensate. Other experiments undertaken on Earth, which explored the yield of oxygen produced under conditions of up to eight times greater gravity than on Earth, enabled the team to produce further data showing that it was possible to extrapolate the results to find reliable results for lower gravity conditions. terms too.

Dr Bethany Lomax, lead author of the paper, was a PhD student at the University of Glasgow School of Chemistry when the research was carried out. She took part in the flights with co-authors Patrick McHugh, also from the University of Glasgow, and Paul Broadley, Gunter Just and Greg Hutchings, from the University of Manchester.

Dr Lomax, now a researcher at the European Space Agency, said: “There seemed to be a gap in the previously reported work, where the drop in efficiency at gravity levels relevant to the Moon and Mars has not been studied experimentally. The experiments that we were able to do on board the parabolic flights in microgravity aimed to fill this gap. After extending these experiments to hypergravity conditions up to 8 g, we were also able to show that there is a correlation between results in both conditions, suggesting that future experiments may not need to go to the same resource-intensive ends as us.

“The process of taking the flights to achieve these results was difficult, not only the nausea of ​​the constant rises and falls during the dishes, but also the organization of a trip from the UK to Germany during the pandemic. The whole team worked very hard to get the experiment ready in time for the flight.

“However, it was worth the observations we were able to make, which we hope will be of real use to future space mission planners. The reduction in efficiency we observed may not seem be a huge difference, but in space missions, where every watt of power must be carefully budgeted, the additional electricity that would be required to match the terrestrial performance of the cells will need to be considered.”

Dr Mark Symes from the University of Glasgow School of Chemistry, co-author of the paper and Dr Lomax’s thesis supervisor, added: “The experiment designed by Dr Lomax was ambitious and required a lot of effort to, literally and metaphorically, get off the ground. However, the findings are a valuable contribution to the growing body of science that will underpin long-term human habitation on other planets. I look forward to seeing how future work can build on these findings.

Researchers from the Universities of Glasgow and Manchester, the European Center for Space Research and Technology in the Netherlands, and the Johns Hopkins University Applied Physics Laboratory in the United States contributed to the article.

The paper, titled “Predicting the Efficiency of Oxygen-Evolving Electrolysis on the Moon and Mars,” is published in Nature Communications. The research was supported by funding from the European Space Agency Networking/Partnership Initiative, the UK Space Agency, the Engineering and Physical Sciences Research Council (EPSRC), the Institution of Mechanical Engineers and the Royal Society.