Scientists think they may have cracked life support for Martian occupation

Outdated ISS system will need an upgrade if we're to go further into space

Researchers have figured out that direct photochemical reactions could provide the oxygen and hydrogen humans need for long-term habitation of Mars or the Moon.

The International Space Station (ISS) relies on photovoltaic-driven water electrolyzers to get oxygen from water. But the two-stage process – converting sunlight into electricity and then using electricity in the electrolysis of water – is costly.

A paper published this week said about 1.5kW out of the 4.6kW energy budget of the Environmental Control and Life Support System on the ISS is used up by the Oxygen Generator Assembly (OGA), which relies on electrolysis. The approach was a dead end in terms of future space exploration and habitation, the study published in Nature Communications states.

As well as the high energy demand, the OGA and the Carbon Dioxide Reduction Assembly "currently in place on the ISS bear the challenge of being notoriously cumbersome and prone to breakdowns due to obsolete, inefficient, or ageing compartments," it said.

As an alternative approach, lead researcher Katharina Brinkert, assistant professor of catalysis at the University of Warwick, assessed the viability of photoelectrochemical (PEC) devices to aid the chances of long-term survival.

PEC devices use semiconductor materials to convert solar energy directly to chemical energy to produce hydrogen and oxygen without requiring the intermediate production of electricity. The technology is the subject of intense research on Earth because it might help in the sustainable energy problem, but its potential in space has yet to be studied.

"This work seeks to establish the theoretical foundations for the application of PEC devices in habitats on the Moon and Mars and delivers the first foray into exploring the feasibility of utilising them for oxygen production and carbon dioxide recycling," Brinkert said in the paper.

The researchers concluded it was possible, but with some caveats.

"Although high long-term efficiencies and power densities of PEC devices are still integral parts of ongoing terrestrial research efforts, we have shown that the application of these devices could go beyond Earth and potentially contribute to the realisation of human space exploration," the paper said.

The research also looked at whether the PEC devices could be built in an extra-terrestrial settlement using In-Situ Resource Utilization (ISRU), meaning what you can find where you've landed.

"The device construction can draw from a variety of semiconductors and electrocatalyst materials that are available on the Moon and Mars and the required materials can eventually be produced via ISRU. Moreover, we have previously demonstrated that PEC devices can work efficiently in microgravity and our theoretical analysis suggests that it can suitably be scaled up," the study said. ®

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