Bacttery 4 Venus

https://arawhoor.wixsite.com/bacttery-4-venus

https://drive.google.com/file/d/1YpgiFOxq57JhNqyt8TLMqeooUXzy-zAv/view?usp=sharing

The plants that transform luminic energy to an electric one, they use it to transmute inorganic matter to organic matter. Thanks to this process, that we call photosynthesis, life is possible in most life beings. Plants and other photosynthetic organisms capture a red photon and use its energy to stimulate an electron of the chlorophyll. This electron is stimulated, transferred and used to propitiate chemical reactions where the energy is stored (Like NADP/NAPDPH or ADP/ATP). But a single molecule of chlorophyll cannot do all this on its own,it requires other molecules that give structure and simplify their action. Every system of molecules overall with their chlorophyll is denominated photosystem (Pérez Uria-Carril, 2009).

Humankind has drawn on the most varied sources of energy but was recently able to reach photosynthetic energy in a straight way. However, Efrati and collaborators (2016) pioneer work had opened doors. The team could isolate the photosystem I of an photoautotrophic organism and associate it to an electrode that could function like a photocathode. Between the electrode and the photosystem was necessary a chemical mediator that could take an electron and give it to the electrode, in this work they used pyrroquinones. When this photosystem is exposed to sunlight, it starts working on the electron generation, giving like product an electric current that would be recollected by an electrode.

In the wild, the autotrophs use part of the energy they transform through photosynthesis to return the chlorophyll to a state where it can give an electron (Pérez Uria-Carril, 2009). However, in order to do that it is required that all the chemical reaction batteries of the chloroplast and the Efrati protopite did not have it. In this way, in their prototype they had to generate an anode where a molecule could be able to give electrons to the chlorophyll, in this case they used glucosidase, capable of oxidizing glucose and giving the resultant electron to the chlorophyll. So the system cycle ends with the use of glucose. 

These solar panels that make artificial photosynthesis were capable of producing 50 to 300 nA per cycle (each cycle takes 20 seconds) depending on the glucose concentration (0 to 20 nM) per unit. Each cm2 can hold 2.7 x 10-10 mol of functionalized photosystems. These promising results triggered research in the biomimetic field in the design of solar panels, which is reflected in the great variety of substances proposed as chemical mediators between the photosystem and the electrode (the most important are found in the quinone’s family), in the different ways of accessing photosynthesis (either using whole cells, intact chloroplasts or extracting only the photosystems), in the different ways of restoring the active state of chlorophyll and in the numerous practical applications (from generation of oxygen, to decontamination of bodies of water, with the incentive of associated energy production). 

Venusian conditions are a challenge for the design of power generation modules. Among the proposed solutions are the generation of chemical energy (batteries and fuel cells), nuclear energy, wind energy (Surampudi, et al, 2017; Brandon, et al, 2020; Landis 2021, Harrison, 2010). But since we are a team made up of students and ex-students of the Highschool of Fine Arts, we decided to go where no one had gone before. We wanted to propose a new concept, a twist because if NASA put together this challenge it was to listen to creative solutions and not repeat the same ideas that it already has on the table. We bring a biomimetic approach. That is, instead of trying to solve the problem from scratch, we look to see if nature has solved that problem and borrow its solution. After all, nature had billions of years to do "trial and error" and we only have 48 hours.

But venus doesn`t make it so easy. Near the Venusian floor the temperatures go up to 400 º C and they do not fluctuate too much, not at night neither at daylight, nor summer or winter, not even in the poles compared to the equator. This is caused by the brutal greenhouse effect that presents thanks to its dense CO2 clouds. This dense atmosphere causes the atmospheric pressure on the surface to stay about 90 consistent bars. It is considered that in the surface in general there are no wind currents and the composition of the atmosphere is 97 CO2, 3 N2 and among the minority elements we highlight SO2 with 20-30 ppm. We say this is “considered” because the same revision works point out that the measures aren't always coherent and that the measuring tools failed more and more as the probes were submerged into Venus's atmosphere (Berh, et al, 2006; Zasova, et al, 2007).

It's clear for us that no terrestrial plant makes photosynthesis on those conditions and that they don't even survive. For that reason to generate our solar panel that would make artificial photosynthesis we needed to find an organism that would live in those same extreme conditions. In a similar way, if the organism survives at this conditions it would have been legitimate to assume that its miomolecules could harness those temperatures and they would not even denaturalize, nor dismantle.

From there we started a hunt for that high temperature and pressure autotroph organism. This way we could go on to progress in the design of an external energy generating module, in the venusian atmosphere and that it wouldn't occupy space inside the thermally isolated module from the lander or rover. This way we could get rid of occupied space for the sake of scientific tools and other modules.

Our organism wouldn't have been a plant nor an algae because both had vital limits of low temperatures, like the 50 º C that Welwistchia mirabilis resists. Our organism was going to be in between the bacteria, that present the most physiology and molecular diversity. The filter that we used was to select the bacteria that where thermophiles (55-80° C) or hyperthermophiles (more than 80° C), that they were also autotrophs and to be possible to get advantage of the spontaneous oxidation of sulfur compounds to recompose its (bacterio)chlorophyll.

Two terrestrial environments were propitious for finding those bacteries. The hydrothermal sources, like the ones from Yellowstone, where the life temperatures of bacteries hang around 80º C and lots of them make oxygenic photosynthesis , that is, the process is very effective but requires more stable conditions. Among them, the purple sulfur bacteria stood out, famous for the classic Winogradsky column experiment.

The other promising environment was the submarine springs and volcanoes. There the magma at more than 1000°C emerges from the crust and comes into contact with the almost anoxic seawater at 4°C. Different bacteria occupy different proliferations in different sub-environments, from those that inhabit the areas of cold springs due to the cooling of the waters between the bottom rocks; those that live immersed in the rocks that form the volcano even float inside the fumarole produced by the escape of gases and light solids (such as volcanic glass). At these depths the sunlight does not reach so life seems unfeasible. However, many bacteria take advantage of the highly reduced sulfur compounds that are released from the eruption and rapidly oxidize spontaneously to use the energy released in the synthesis of organic matter. We call this process chemosynthesis. Even a few bacteria are able to photosynthesize in that darkness, but they don't take advantage of the sunlight (which doesn't reach it), instead they use the glow given off by the lava and do anoxygenic photosynthesis with red and near-infrared light.

After evaluating the biology of more than 30 different bacteria (Holger, et al, 1985; Dick, 2019; Fujikura, et al, 1999; Beatty et al., 2005; Zavarzina,et al, 2007; Guezennec, et al, 1998; Crespo-Medina, 2009; Labrador, et al, 2018; Van Dover, 2021). Our best candidates are:

-green sulfur bacteria, such as Chlorobia, that photosynthesize in red and is associated with the oxidation of sulfur. It lives at high temperatures (80°C) but low pressures (1 atm) (Holger, et al, 1985; Dick, 2019). The problem with this beautiful bacterium is that in principle it does not resist high pressures, although this does not have to be the case for its biomolecules. The second problem that we face is that the sulfur compounds that can be used in nature are usually very reduced and oxidize quickly. In venus the sulfur compounds present are SO2 where the sulfur is highly oxidized (+4) and its only possibility of being reduced is to lose 2 electrons and go to +6. But that only happens spontaneously in the presence of water (write reaction and quote) or oxygen (write reaction and quote). Carrying one of these reagents is the only viable option we can find, which would moderately increase the weight of the power module.

-a bacterium (GSB1) that photosynthesizes with the red and infrared emitted by the glow of lava in submarine volcanoes. It lives at 120° C and at more than 200 bars of pressure inside the chimneys of submarine volcanoes (Beatty et al., 2005). The problem that this bacterium in particular poses to us is the recomposition of the bacteriochlorophyll, which in principle should be assisted with a fuel (glucose or another organic substance, or through a spontaneous but controllable inorganic reaction). This implies at least bringing part of the reagents from the Earth.

Our proposal for an artificial photosynthesis panel would work in two subunits: a photocathode that delivers electrons to the circuit as electrical energy, and an anode that oxidizes a substance and recomposes the bacteriochlorophyll so that it can be re-excited.

The photocathode would be composed of a vitreous electrode of Indium Tin Oxide (ITO) or one of its alternatives (such as graphene or carbon nanotubules). However, ITO electrodes are in principle viable since their melting point is between 1526–1926 °C, well above Venusian surface temperatures.

The electrode is impregnated with a chemical mediator, responsible for transferring the electrons generated by the photosystem to the electrode. This chemical mediator is usually a quinone. Efrati et al. (2016) used pyrroquinones but currently the most used are benzoquinones (Weliwatte, 2021), although the best results with ITO have been shown by naphthoquinones due to their ability to establish electrostatic interactions with ITO (Kato, et al. , 2012). It will be necessary to analyze in the laboratory the behavior of the different chemical mediators proposed in the Venusian conditions of temperature and pressure.

An electron is released by the photosystem by interacting with a red or infrared photon (depending on the bacterium chosen as the source of the photosystems). Once released, the bacteriochlorophyll is oxidized and it is necessary to spend energy to reduce it so that it can act again. In the prototype of Efrati et al (2016) this energy to reestablish the bacteriochlorophyll used glucoxidases capable of oxidizing glucose.

To make up for this deficit on the surface of Venus, we considered various solutions: the first option is glucose or another simple sugar with a high boiling point (300°C for refined sucrose and 500°C for the mixture of sucrose and various known minerals, like brown sugar). The presence of another sugar does not require replacement of the glucoxidase enzyme since these molecules are capable of oxidizing other sugars such as sucrose. This method would have the advantage that it has proven effective in the laboratory but requires the transport of sugar to the surface of Venus.

Our second option was the use of the oxidation of sulfur compounds. The many bacteria that take advantage of this process are a source of biomolecules that carry out the desired reaction. The problem that we found is that no bacteria that we could find is capable of oxidizing S+4 to S+6.

So we decided to try an industrial approach to this part of the problem. We found that during the industrial processes of sulfuric acid production these reactions take place. The dissolution of SO2 in H2O produces the oxidation of sulfur giving rise to SO4+2. So we should only take the water and let the Venusian atmosphere interact with the steam in a controlled way to be able to capture the resulting electrons and restore the bacteriochlorophyll. The drawback of this is that the enormous amount of CO2 produces carbonic acid and the reaction is not the desired one.

Another option is to expose to the atmosphere a substance that has a greater affinity for SO2 than for CO2, such as vanadium pentoxide, which is the catalyst for the oxidation of sulfur in the transformation of SO2+O2 into SO3. Here the challenge is to carry oxygen or obtain it from the local atmosphere. In both cases it would be necessary to carry the catalyst and that increases the weight of the energy module. However, the studies do not agree on the proportions of O2 in the atmosphere below 15 km. Some affirm 10 ppm others total absence.

With any of the selected bacteria, the problem of reconstituting the bacteriochlorophyll remains so that the system is sustainable over time. However, other variables have weighed in favor of the GSB1 bacterium, extracted from the volcanic edifice itself (Beatty et al, 2005). This bacterium lives floating in the fumarole of submarine volcanoes near Costa Rica at 120°C and almost 200 atm, however other records of this same bacterium suggest that the life conditions of this bacterium could be around 300°C. These conditions are the most similar to the Venus to which a terrestrial organism proliferates.

GSB1 requires anoxia to proliferate, a condition guaranteed on Venus. But it is capable of resisting exposure to oxygen for up to two weeks, which facilitates its handling for the extraction of the photosystem and its assembly in the panel.

In addition, it reconstitutes its bacteriochlorophyll by reducing Sulfur, with which it is possible that its study will find useful biomolecules in the design of a recomposition system that replaces the oxidation of glucose in the panel and does not require the transport of great weight to Venus.

Our favorite bacterium presents Bacteriochlorophyll c (BChl c) whose light absorption peaks are in the green (550 nm) and red and near infrared (700-800 nm). The magma that flows through the submarine volcanoes it inhabits emits photons in the red and near infrared (700-800 nm) 4 orders of magnitude more than it does at other wavelengths. GBS1 is capable of photosynthesizing and proliferating with these photons, although it does not exhibit its greatest growth unless green photons are present (Beatty et al., 2005).

A recent study (Wood et al., 2022) based on data from the Parker Solar Probe was able to directly assess for the first time the light spectrum of Venus in the visible range. The study collected red and near-infrared images on one of its flybys en route to the sun showing that the ground of Venus emits red and near-infrared light. The emission peak was found around 775 nm. In the words of the first author “Venus ground is glowing red”. These images taken on the night side of Venus are promising since, if these observations are corroborated in its new step in November 2024, they would show that it is possible to generate electrical energy with our artificial photosynthesis panel even on the night side of Venus, and even oriented towards the ground instead of the sky.

Photosynthesis involves the absorption of photons and their use in the generation of electrical energy that powers the rover/lander. The absorption of photons in the heat radiation range of the Venusian soil would have as a secondary effect that those photons would never reach the module, so they would never heat the module. This effect could be used to cool the module either by absorbing radiation from the ground or even interfering with direct solar radiation.

References from NASA and associated agencies

Brandon, E. J., Bugga, R., Grandidier, J., Hall, J. L., Schwartz, J. A., Limayne, S. (2020). power beaming for long life venus surface missions. Niac 2019 Phase 1

Landis, G.A., Harrison, R., (2010). Batteries for Venus Suface Operation. Journal of propulsion and power Vol.26, 4, July-August 2010

Surampudi, R., et al. (2017). Energy Storage Technologies for Future Planetary Science Missions. Nasa resources space apps challenge, Challenge: Exploring venus

Wood, B. E., Hess, P., Lustig‐Yaeger, J., Gallagher, B., Korwan, D., Rich, N., ... & Raouafi, N. E. (2022). Parker Solar Probe imaging of the night side of Venus. Geophysical Research Letters, 49(3), e2021GL096302.

We are “Bacttery 4 Venus”, a team composed by students and former students from Bachillerato de Bellas Artes (Fine Arts Highschool) that decided to investigate what no space agency had investigated before. It all began in a classroom where our team was determined to work hard to change the world.

The first time we heard about the Space Apps Challenge, we were really excited about the opportunity of being able to contribute to science with some new ideas. With this in mind, we looked up the available challenges so we could join in the one that most of us were interested in and we could develop a solution in an innovative way. “Exploring Venus Together” presents us a real challenge not only because of the difficulty of the challenge itself, but also because of the limited knowledge we have about this planet. Choosing this challenge made us acquire knowledge in multiple areas, like microbiology for example, that we required to be able to develop the solution with this different focus, the biomimetical one, where the nature and its study helped us to finally make it.

We would really like to thank all the organizators and tutors of the event that made the experience simply incredible as well as all the external people of the event that were there to give us a hand.

Beatty, J. T., Overmann, J., Lince, M. T., Manske, A. K., Lang, A. S., Blankenship, R. E., ... & Plumley, F. G. (2005). An obligately photosynthetic bacterial anaerobe from a deep-sea hydrothermal vent. Proceedings of the National Academy of Sciences, 102(26), 9306-9310.

Bergh, C., Moroz., Taylor, F.W., Crisp, D., Bézard, B., Zasova, L.V. (2006). the composition of the atmosphere of venus below 100km altitude:an overview. Planetary and space science 54 (2006) 

Crespo-Medina, M. (2009). Diversity of chemosynthetic thiosulfate oxidizing bacteria from diffuse flow hydrothermal vents and their role in mercury detoxification. Rutgers The State University of New Jersey-New Brunswick.

Dick, G. J. (2019). The microbiomes of deep-sea hydrothermal vents: distributed globally, shaped locally. Nature Reviews Microbiology, 17(5), 271-283.

Efrati, A., Chun-hua Lu., Michaeli, D., Nechushtai, R., Alsaoub, S., Schuhmann, W., Willner, I. (2016). Assembly of photo-biolectrochemical cells using photosystem I-functionalized electrodes. Nature energy Volume: 1, P: 1-8k

Fujikura, K., Kojima, S., Tamaki, K., Maki, Y., Hunt, J., & Okutani, T. (1999). The deepest chemosynthesis-based community yet discovered from the hadal zone, 7326 m deep, in the Japan Trench. Marine Ecology Progress Series, 190, 17-26.

Guezennec, J., Ortega-Morales, O., Raguenes, G., & Geesey, G. (1998). Bacterial colonization of artificial substrate in the vicinity of deep-sea hydrothermal vents. FEMS microbiology ecology, 26(2), 89-99.

Jannasch, H. W., & Mottl, M. J. (1985). Geomicrobiology of deep-sea hydrothermal vents. Science, 229(4715), 717-725.

Kato, M., Cardona, T., Rutherford, A. W., Reisner, E. (2012). Photoelectrochemical water oxidation with photosystem 2 integrated in a mesoporous indium-tin oxide electrode. Journal of the American Chemical Society, 134,8332-8335.

Labrador, C. R., Hurtado, A. A. H., & Carrascal, J. I. S. (2018). Búsqueda de bacterias oxidadoras de azufre para su potencial uso en la producción de biogás de alta pureza. Revista de Investigación Agraria y Ambiental, 9(2), 295-304.

Pérez Uria-Carril, E. (2009). Fotosíntesis: aspectos básicos. REDUCA (Biología) Vol. 2, Núm. 3 (2009)

Van Dover, C. L. (2021). The ecology of deep-sea hydrothermal vents. In The Ecology of Deep-Sea Hydrothermal Vents. Princeton University Press

Weliwatte, S. N., Grattieri, M., Shelley Mineteer, D. (2021). Rational design of artificial redox-meditating systems toward upgrading photobioelecrocatalysis. Photochemical & Photobiological Siences (2021)

Zasova, L.V., Ignatiev, N., Khatuntsev, I., Linkin, V. (2007). Structure of the venus atmosphere. Planetary and space science 55 (2007)

Zavarzina, D. G., Sokolova, T. G., Tourova, T. P., Chernyh, N. A., Kostrikina, N. A., & Bonch-Osmolovskaya, E. A. (2007). Thermincola ferriacetica sp. nov., a new anaerobic, thermophilic, facultatively chemolithoautotrophic bacterium capable of dissimilatory Fe (III) reduction. Extremophiles, 11(1), 1-7.

#Biology; #Biomimesis; #SolarCells; #Photosystems; #ArtificialPhotosynthesis; #Bacteria; #Extremophyles