Martian Biofuel Could Enable Flights Back to Earth

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Many companies and organizations have aspirations of reaching and one day colonizing Mars. The trip will take about seven months, and it's seen as a one-way ticket, although getting a return flight isn't impossible. Rocket engines destined for Mars currently use methane and liquid oxygen (LOX) as a propellant. To get a spacecraft back to Earth, NASA, SpaceX, or whoever is headed out would need to send about 30 tons of fuel to the red planet at an expense of roughly $8 billion.

Researchers at the Georgia Institute of Technology have created a new process to manufacture rocket fuel on the red planet that could be used to send astronauts back to Earth one day. The team came up with a concept that calls for huge photobioreactors that are about the size of four football fields.

The bioproduction process would use carbon dioxide, sunlight, and frozen water, all available on Mars. It would also require sending cyanobacteria (algae) and engineered E. coli from Earth. The algae would take CO2 from the Martian atmosphere and create sugars using sunlight. The E. coli would convert the sugars into the propellant, 2,3-butanediol, which does exist on Earth, but we use it to make polymers used in rubber production.

Remember that Martian gravity is about 33% of that on Earth, which allowed researchers to get creative with potential fuels and arrive at 2,3-butanediol.

Georgia Tech's biotechnology-based in situ resource utilization (bio-ISRU) strategy can also produce liquid oxygen (LOX) from CO2. The process would also generate about 44 tons of excess clean oxygen, which could be useful for the colonizers who decide to hang back.

NASA has previously proposed a method to convert Martian CO2 into LOX, but it would still require methane shipped from Earth.

To get started on the project, materials would have to be sent to Mars to assemble the massive photobioreactors. Before that, the project still needs some work. While Georgia Tech's process uses 32% less power than NASA's alternative, the photobioreactors' components weigh about three times more.

So, the team is now working on ways to make the bio-ISRU process lighter. One way would be to improve the speed at which cyanobacteria grow on Mars, which would allow the team to scale back the photobioreactor significantly.

The team recently outlined the production process in the journal Nature Communications.

Image Credit: NASA

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