Photovoltaics can be more practical for long stays on Mars thanks to today’s lightweight, flexible solar panels. According to new research by scientists at the University of California, Berkeley, the high efficiency, lightness and flexibility of current solar cell technology means that photovoltaics could provide all the electricity needed for a prolonged mission to Mars or even a permanent installation on the Red Planet. Most scientists and engineers who have examined the life of the surface of Mars have assumed that nuclear energy is the best choice, due in large part to its reliability and operation 24 hours a day, 7 days a week. Kilopower tiny nuclear fission reactors have improved over the past decade to the point where NASA considers them a safe, efficient and abundant source of energy, as well as a key to future robotic and human exploration. Solar energy, on the other hand, must be stored for use at night, which lasts about the same amount of time on Mars as it does on Earth. And the persistent red dust that covers everything on Mars can limit the energy production of solar panels. After a huge dust storm on Mars in 2019, NASA’s nearly 15-year-old rover Opportunity, powered by solar panels, stopped operating. An artist’s performance of a photovoltaic-powered Martian industrial crew capable of synthesizing food and pharmaceuticals, making biopolymers and recycling biowaste. Creation: A work of art by Davian Ho The new study, published April 27, 2022 in the journal Frontiers in Astronomy and Space Sciences, uses a systems approach to compare these two technologies head-on for an extended six-man mission to Mars that includes a 480-day stay on the surface. planet before returning to Earth. This is the most likely scenario for a mission that reduces transit time between the two planets and extends the time on the surface beyond a 30-day window. Their analysis found that for settlement sites over almost half the surface of Mars, solar energy is comparable or better than nuclear energy, given the weight of solar panels and their efficiency – if little energy is used during the day. for the production of hydrogen gas for use in fuel cells to supply the colony at night or during a sandstorm. “The production of photovoltaic energy in combination with certain energy storage configurations in molecular hydrogen exceeds nuclear fusion reactors over 50% of the planet’s surface, mainly in those areas around the equator, which is in stark contrast to this. which has been repeatedly suggested in the literature, which is that it will be nuclear energy, “said Aaron Berliner, a doctoral student in industrial engineering at UC Berkeley, one of the first two authors of the study. Astronauts traveling to Mars should minimize the weight of the power system they take with them from Earth. Photovoltaics would be the best choice if their planned settlement location is in the yellow area on this flat map of Mars. It also shows the locations of previous missions that have landed on Mars, including the Jezero crater (top right), which is currently being explored by NASA’s Perseverance rover. Made by: Image by Anthony Abel and Aaron Berliner, UC Berkeley The study gives a new perspective on the colonization of Mars and provides a roadmap for deciding what other technologies to use when designing manned missions to other planets or moons. “This paper provides an overview of what energy technologies are available and how we can develop them, what are the best uses for them and where they end up,” said co-author Anthony Abel, a graduate student in the Department of Chemistry. and Biomolecular Engineering. “If humanity collectively decides that we want to go to Mars, this kind of system-level approach is necessary to achieve it safely and minimize costs in an ethical way. We want to have a clear comparison between the options, whether we decide which technologies to use, which locations to go to Mars, how to go and who to bring. ”

Larger missions have higher energy needs

In the past, NASA estimates of astronauts’ energy needs on Mars have generally focused on short stays that do not require energy-intensive processes for building food, building materials, or producing chemicals. But as NASA and company leaders now build rockets that could go to Mars – including Elon Musk, SpaceX CEO and Jeff Bezos, founder of Blue Origin – they are discussing the idea of ​​long-term, extraterrestrial, larger, and more Reliable energy sources must be considered. The complication is that all of these materials must be transported from Earth to Mars at a cost of hundreds of thousands of dollars per pound, making low weight necessary. People on Mars will need to use the only available raw materials – ice water, atmospheric gases, Mars soil and sunlight – to make everything they need to survive. Researchers like those at UC Berkeley-based CUBES are working on ways to convert these raw materials into food, medicine, fuel and building materials. This flowchart shows how in situ resource use (ISRU) converts raw materials into a form that can be used for food and drug synthesis (FPS) and biopolymer fabrication (ISMUs) for crew use. Waste is collected and reused (loop closure or LC) to maximize efficiency and reduce logistics costs from Earth. Realization: Illustration by Aaron Berliner and Davian Ho, UC Berkeley A key need is power for biomass plants that use genetically modified microbes to produce food, rocket fuel, plastics and chemicals, including drugs. Abel, Berliner, and their co-authors are members of the Center for the Utilization of Biological Engineering in Space (CUBES), a multidisciplinary effort to modify microbes using synthetic biology gene insertion techniques to provide the necessary supplies for a colony. The two researchers found, however, that without knowing how much power would be available for an extended mission, it was impossible to assess the practicality of many biomass processes. Thus, they began to create a computerized model of various power supply scenarios and potential energy requirements, such as habitat maintenance – which includes temperature and pressure control – production of fertilizers for agriculture, production of methane for rocket propulsion to return to Earth, and production of bioplastics for manufacture of spare parts. Unlike a nuclear system, Kilopower was photovoltaic with three energy storage options: batteries and two different techniques for producing hydrogen gas from solar energy – by electrolysis and directly from photoelectrochemical cells. In the latter cases, hydrogen is compressed and stored for future use in a fuel cell for energy production when the solar panels are not. Only electrolysis photovoltaic energy — using electricity to split water into hydrogen and oxygen — was more competitive with nuclear power: It proved to be more economical per kilogram than nuclear power on almost half the planet. The main criterion was weight. The researchers hypothesized that a rocket carrying a crew to Mars could carry a payload of about 100 tons without fuel, and calculated how much of that payload would need to be dedicated to a power system for use on the planet’s surface. A trip to and from Mars would take about 420 days – 210 days at a time. Surprisingly, they found that the weight of a power system would be less than 10% of the total payload. For a landing site near the equator, for example, they estimated that the weight of solar panels plus hydrogen storage would be about 8.3 tons, compared to 9.5 tons for a Kilopower nuclear reactor system. Their model also determines how to modify photovoltaic panels to maximize efficiency for different conditions at locations on Mars. Latitude affects the intensity of sunlight, for example, while dust and ice in the atmosphere can scatter longer wavelengths of light.

Advances in photovoltaics

Abel said photovoltaics are now extremely efficient at converting sunlight into electricity, although better performance is still expensive. The most critical new innovation, however, is a lightweight and flexible solar panel, which facilitates storage on the outgoing rocket and lower transport costs. “The silicon panels you have on your roof, with steel construction, glass base, etc., just will not compete with the new and improved nuclear ones, but the newer lightweight, flexible panels suddenly really change that talk. Said Abel. He also noted that the lower weight means that more panels can be moved to Mars, providing backup material for any panels that fail. While kilowatt nuclear power plants provide more power, they need less, so if it fell, the colony would lose a significant percentage of its power. Berliner, who also has a degree in nuclear engineering, entered the project with a bias toward nuclear energy, while Abel, whose undergraduate dissertation was on new innovations in photovoltaics, was more in favor of solar energy. “I feel that this document really stems from a sound scientific and mechanical disagreement about the benefits of nuclear power over solar energy, and that it’s really up to us to try to figure it out and settle a bet,” Berliner said. “Which I think I lost, based on the configurations we chose to publish it. But it is a happy loss, for sure. “ Reference: “Photovoltaic-Based Energy Production Can Support Human Exploration on Mars” by Anthony J. Abel, Aaron J. Berliner, Mia Mirkovic, William D. Collins, Adam P. Arkin and Douglas S. Clark, 27 April 2022, Frontiers in Astronomy and Space Sciences.DOI: 10.3389 / fspas.2022.868519 Other co-authors of the work are Mia Mirkovic, a researcher at UC Berkeley at Berkeley Sensor and …