If we can perfect artificial photosynthesis, we can thrive in space

By 2030, many space agencies will send astronauts to the moon for the first time since the Apollo program ended more than 50 years ago. These programs will create permanent infrastructure, such as Moon GateAnd Artemis base campMoon Village and the International Lunar Research Station (ILRS). In the next decade, the first manned missions to Mars are expected to occur, culminating in the establishment of the first human outposts on another planet. Commercial ventures also want to create habitats in low Earth orbit (LEO), enabling everything from asteroid mining to space tourism.

One of the biggest challenges in this renewed era of space exploration (Space Age 2.0) is ensuring that humans stay healthy while spending extended periods in space. Chief among them is ensuring that crews have functioning life support systems that can provide a steady supply of breathable air, which poses its own technical challenges. In a recent study, a team of researchers led by Katharina Brinkert From the University of Warwick Cave artificial photosynthesis It could lead to a new type of life support system that is smaller, lighter, easier and more cost-effective to send into space.

In addition to being an Assistant Professor in Motivation at the University of Warwick (UoW), UK, Dr Brinkert is a researcher in Center for Applied Space Technology and Microgravity (ZARM) at the University of Bremen, Germany. join it Byron Ross, A Ph.D. Student with Dr. Brinkert’s research group (which led the study) in the Department of Chemistry at the University of Washington, W Sophia HausnerHe is an associate professor at Institute of Mechanical Engineering at Ecole Polytechnique Fédérale de Lausanne (EPFL). A paper describing their latest research appeared on June 6th in Nature Communications.

Nearly 4 billion years ago, Earth’s atmosphere and environment were much different than they are today. Known as Archean Eon, the planet was covered in active volcanoes, and its atmosphere was composed mostly of carbon dioxide (CO.₂) and sulfur dioxide and other volcanic gases. During this same period, the first forms of life are believed to have emerged: single-celled microbes that depended on retinol, or chlorophyll, for photosynthesis. These life forms slowly transformed the atmosphere, combining water, sunlight, and carbon dioxide₂ To produce glucose (an energy source) and oxygen gas as a by-product.

This led toThe great oxidation eventand the emergence of more complex life forms, eventually leading to humans and Homo sapiens (aka humanity). Photosynthesis for life on Earth is an integral part of that, with scientists hoping to harness the process to make it easier to live in space. International Space Station (ISS), astronauts depend on Environmental control system and life support (ECLSS) to provide a constant supply of oxygen. This system is based on electrolysis, with electricity from the station’s solar panels splitting water into hydrogen and oxygen gas.

Meanwhile, a separate system “cleans” carbon dioxide from the air and converts it into water and methane. Unfortunately, these systems are large, bulky, difficult to maintain, inefficient, and require about a third of the energy needed to run ECLSS. Replenishing the system is relatively easy as missions in low Earth orbit (LEO) can be resupplied in a matter of hours. But for missions to Mars, which can take six to nine months in transit and take up to three years, resupply missions aren’t practical. As Dr. Brinkert said in a recent op-ed with Conversation:

Therefore, the search for alternative systems that can be used on the moon and on trips to Mars continues. One possibility is to harvest solar energy (which is abundant in space) and use it directly to produce oxygen and recycle carbon dioxide in just one device. The only other input into such a device is water – similar to the process of photosynthesis that occurs in nature. This would circumvent complex setup processes where light harvesting and chemical production are separated, as is the case on the International Space Station.”

Instead of chlorophyll, which plants and algae rely on to absorb sunlight, a photovoltaic system (PEC) will rely on semiconductor materials surrounded by metal catalysts to convert carbon dioxide and water into oxygen gas and hydrogen/carbon-based fuels. The extra energy from solar heating can be harnessed to directly catalyze the water and speed up the chemical process, thus requiring less electricity. This life support system will be extremely useful for long-range missions because it will combine reduced size and weight with increased efficiency.

Moreover, the system will be easier to maintain because it requires less complex wiring and mechanical components. To test this concept, Dr. Brinkert and colleagues produced a theoretical framework to measure the performance of PEC versus conventional BLSS. This included efficient solar water splitting, available solar energy on Mars (about half of what Earth receives), and reducing carbon dioxide in the Martian atmosphere. Finally, they studied how solar concentrator devices can assist PEC devices and how they can be fabricated through on-site resource utilization (ISRU). Blinkert said:

On Mars, the atmosphere [is composed] It contains approximately 96% carbon dioxide – which seems ideal for an artificial photosynthetic device. But the intensity of light on the Red Planet is weaker than on Earth due to the greater distance from the Sun. Does this pose a problem? We have already calculated the intensity of sunlight available on Mars. We showed that we can actually use these devices there, although solar mirrors are becoming more important.

Our analysis shows that these devices will indeed be viable to complement existing life support technologies, such as the oxygen generator set used on the International Space Station. This is particularly the case when combined with devices that concentrate solar energy in order to power reactions (mainly large mirrors that focus incoming sunlight).

This proposed system presents several advantages over conventional electrolyzers, which operate at high temperatures and require a lot of electricity. While NASA is studying technology that can harvest oxygen directly from lunar regolith, this method requires very high temperatures to convert elemental oxygen into oxygen gas (O2). On the other hand, PECs can operate at room temperature within the habitats of Mars and the Moon, using water as the main resource. The abundance of water ice on Mars and in its crater Antarctic-Aitken Basin makes this method particularly attractive.

The technology is still in its infancy and requires several more years of additional research, Blinkert says. But the potential returns would be enormous, from lightweight life-support systems for long-duration missions to artificial atmospheres for habitats in low-Earth orbit, on the Moon, and on Mars. But of course, the benefits will go beyond space exploration and could have applications here at home. Blinkert said:

“[T]The insights we gain from designing and manufacturing these devices can help us meet the challenge of green energy on earth. We are fortunate enough to have oxygen-producing plants and algae. But artificial photosynthesizers can be used to produce hydrogen or carbon-based fuels (instead of sugars), opening a green path to producing energy-rich chemicals that we can store and use for transportation. Space exploration and our future energy economy have a very similar, far-reaching goal: sustainability. Artificial photosynthesis devices may become a key part of making this happen.”

This research mirrors similar efforts to develop life support systems that mimic biological systems here on Earth. This proposed vital life support systems BLSS can regenerate itself over time, providing oxygen, water and even food in a sustainable way. The development of this technology will ensure humanity’s future in space and allow for a more sustainable life here on Earth, helping to mitigate the effects of climate change.

Further reading: ConversationAnd Nature Communications