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Plasma can be used to make oxygen on Mars, study finds

An international research team’s plasma-based method to generate oxygen on Mars could have implications for climate change on Earth.

(CN) — As the prospect of humans colonizing space moves further from science fiction and closer to reality, University of Lisbon physicist Vasco Guerra is on the hunt for a long-term solution to find oxygen on the currently inhospitable Mars.

Two significant problems stand in his way.

First, decomposing carbon dioxide molecules to extract oxygen is a difficult process.  Second, “once carbon dioxide is decomposed, carbon monoxide and oxygen tend to recombine to form back C02,” Guerra, a professor at the University of Lisbon, said.

To find a way to generate oxygen on Mars, Guerra collaborated with an international team of researchers on a study published Tuesday in the Journal of Applied Physics.

That’s where in-situ resource utilization (ISRU) came in.

“In the context of space exploration,” Guerra said in an email to Courthouse News, “an ‘in-situ resource’ is something that can be harnessed in the exploration site, that would have to be brought from Earth otherwise.”

Through ISRU, the researchers can harness and process local Martian resources to generate products. Their focus was harnessing oxygen from the carbon dioxide (CO2) molecules that constitutes most of Mars’ atmosphere.

To help this, the study says, the researchers created a plasma-based method.

“The idea came during a lecture Professor Dava Newman gave at my university (Instituto Superior Técnico, Universidade de Lisboa) in November 2015,” Guerra said. “At the time I was leading a project on plasma reforming of carbon dioxide on Earth, studying how to use CO2 as a raw material to produce fuels using green energy.”

According to Guerra, he started wondering how the team could adapt C02 reformation on Earth to the Martian production of oxygen. At first, he and his colleagues joked about its applicability, “discussing it like kids in the playground,” he said. However, as time went on and their thoughts became more in focus, they began to see that their idea might be plausible. Eventually, the team decided to test it out.

After all, according the study, plasma as the fourth natural state of matter contains free charged particles such as electron and ions.

“In particular,” Guerra said, “the atmospheric composition, the ambient pressure and temperature all play in favor for a plasma process.”

Together with colleagues at France's Ecole Polytechnique and the Dutch Institute for Fundamental Energy Research (DIFFER), the team demonstrated plasma technologies’ feasibility with two experimental campaigns.

In the first campaign, the researchers inserted a plasma reactor inside a cold bath of dry ice and ethanol to replicate Martian temperatures. The cold Martian temperatures increased the CO2 vibrational degree on non-equilibrium. Because they designed the plasma setup for fundamental research and not a prototype, the researchers saw the results as encouraging.

The second campaign tested microwave (MW) discharges under Martian composition and pressure. The researchers found the process can provide CO2 conversions of about 35% for a power around 300 W and gas flow of 50 sccm, bringing the plasma result “to a very competitive standard,” per the study.

This research, aimed at space exploration, could also provide a means of addressing climate change on Earth through what Guerra called the “carbon capture and utilization” (CCU) strategy.

“In this approach, carbon dioxide is not considered as a pollutant but rather as a raw material to be converted into value-added chemicals and green fuels,” he said. “This is key in addressing climate change, as any technology that recycles CO2 for further usage contributes to the reduction of greenhouse gas emissions.”

For now, the team is moving toward assembling a prototype. With some funding from the European Space Agency and other national projects, the team will be even closer to optimizing the reactor and making it competitive.

And then they're one step closer to flying it to Mars.

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