Same in deep space

All the technologies to eliminate carbon dioxide and produce oxygen when we live too far from home. In-depth analysis of Lucca Longo

We have a few years to change the way we live, to learn how to produce energy sustainably, contain the increase in carbon dioxide and stop climate change. If we don’t succeed, we can “simply” change the planet.

To be able to move around the Earth, we must solve some small problems: The moon has no atmosphere. Mercury, too, with temperatures as high as 450 degrees Celsius. Venus is also Hell with a temperature of 380 degrees Celsius, and it has an atmosphere of 97% carbon dioxide and a pressure of 98 times greater. All other planets are completely out of the way, except for Mars. However, 95% of the atmosphere on Mars is composed of carbon dioxide, average temperatures around -63 ° C and pressure is one-tenth of that on Earth. With a dry, wrapped suit like Siberian Inuit, we can even make it for a few hours but the problem of how to live longer still needs to be resolved.

If we try to colonize Mars – or unlikely, at least for the next few centuries, other distant planets – we will not be able to exploit the many technologies that have allowed us to travel and work in space around Earth on board spacecraft and space stations.

In particular, to produce oxygen and Eliminate carbon dioxide, We will not be able to use solutions that We have already submitted it here. All of these technologies, in fact, involve consuming reagents and turning them into waste. We need a supply chain connected to the ground. On the other hand, a journey to Mars takes at least 150 days to 300 days (five to ten months) and we can only make it every two years, when the orbits of both planets approach them. The Curiosity spacecraft took about 8 months to travel – between 2011 and 2012 – while the opportunity was faster and covered the flight in just over 7 months – between 2003 and 2004 – the last NASA spacecraft – Determination Abandoned after 203 days travel in February 2021.

For this, future space colonies will have to fend for themselves for years. They will have to organize themselves according to strict circular economy rules as all waste generated is recovered and recycled on site into new usable materials. Thanks to the energy of the sunOr other stars or artificial fusion.

To capture carbon dioxide and remove it from the colony’s habitat, it will not be possible to use the simple scrubbers (purifiers that remove carbon dioxide) used on the International Space Station, due to a periodic mechanism for internal CO2 absorption followed by absorption in the vacuum of space in the atmosphere cannot function Mars’ atmosphere is already saturated with carbon dioxide. Experimental systems like Moxie, Which converts carbon dioxide into precious oxygen and carbon monoxide, or A. Cyclo Sabater Which – thanks to the electrolyzer – consumes the water vapor released from respiration and turns it into oxygen and hydrogen. The latter then reacts with carbon dioxide to form two precious molecules: water and methane. To eliminate carbon dioxide, other techniques are being studied, such as Bush reaction, Leading to water, carbon steel, or Reverse reaction to exchange water and gas That produces water and carbon monoxide, or finally High temperature electrolysisThat turns it into oxygen and carbon monoxide. A very recent study suggests using Low temperature plasma To convert carbon dioxide into other products.

In all these cases, an energy source is required to make chemical reactions move “backward” – that is, to transfer carbon dioxide – which is the most oxidative and stable form of carbon and thus devoid of energy – to other forms where it is less oxidative and more reactive, that is, it contains energy that can be Launch it and use it.

We will have to face some big problems: First of all, we will need a lot of solar panels, because Mars is farther from the Sun than Earth and the light energy that succeeds in getting there is only 590 watts per square meter instead. From 1000 watts / m2 that reach. On our planet. These panels will have to withstand frequent dust storms, with gusts of 100 km / h rising to 1000 km from the surface accompanied by strong electrostatic discharges from the absence of moisture. Under these conditions, any apparatus exposed to external conditions will wear out very quickly and settlers will have to repair it immediately and with available material so that they do not endanger the entire habitat.

For this reason, the research is heading towards a completely different solution: getting rid of carbon dioxide and turning it into oxygen, so why not embrace it. The oldest technology in the world? Several experiments are underway to use air recycling systems based on photosynthesis of chlorophyll.

In Arizona, the Biosphere-2 project has seen 8 terranes – turned settlers / farmers – live for two years in a huge greenhouse: a sealed 180,000 cubic meter industrial ecosystem. But will there be enough light on Mars? The Mars Society has found the answer: At the Martian Arctic Station built on Devon Island – between Canada and Greenland at 75 degrees north latitude and with insolation and temperature compared to regular Mars – a crew of six colonists verified your ability. Growing tomatoes (in greenhouses of course!).

In Siberia, the BIOS-3 project selected algae over terrestrial plants and showed that only 315 m3 of the chlorella algae-filled bioreactors are required to balance the O2 / CO2 ratio for a single cosmic colonist. With LEDs optimized for photosynthesis, only 1.8 kW of electrical power per head suffices: more or less like an oven in a home.

As we design the spaceships that will take us who knows where, the search continues on the vital habitats that will host the future … the direct space farmers.

(The summary of the article was published at eni.com)