Photoelectrochemical investigation of cyanobacteria coated electrodes under cosmic radiation

The conversion of sunlight to usable energy is realized innature by photosynthesis e.g. in plants and cyanobacteria viathe oxidation of water and is known as “primary production”(of biomass), while in technologies making use of photoelectrodes, it is known as electricity generation through solar(photovoltaic) cells. A shortcoming of solar cells is that theelectricity obtained this way cannot be easily stored. Production of easily stored and transported synthetic fuels, such ashydrogen, by sunlight can be done by (i) a combination ofsolar cells and an electrolyzer, or (ii) photoelectrochemicalcells (Braun 2019, 2020). A novel approach is to functionalizephotoelectrodes with components from the photosyntheticapparatus, such as light harvesting proteins (Bora et al. 2012,2013), or even with live cyanobacteria or microalgae (Braunet al. 2015; Ryzhkov, Colson, Ahmed, Pobedinskas, Haenen,and Braun 2024; Ryzhkov, Colson, Ahmed, Pobedinskas, Haenen, Janssen, et al. 2024). Cyanobacteria and microalgae areconsidered as the primary natural food or oxygen supply forlife support systems in space missions and space exploration(Fahrion et al. 2021; Mapstone et al. 2022). We extend therange of application of such organisms to the continuous production of solar fuel in space missions, instead of just usingthem as biomass, i.e. as supplementary food. One criticalaspect for bringing animate and inanimate matter into spaceis that it will be subjected to elevated levels of cosmic radiation and hence may become damaged, directly or indirectly(genetically). This is why astronauts, for example, must wearspace suits as radiation shields. Our partners at the BelgianNuclear Research Center (SCK CEN), Mol, Belgium previously tested the survival of the cyanobacterium Limnospiraindica PCC 8005 when subjected to acute and chronic dosesof ionizing radiation e.g. 60Co gamma rays (Badri et al. 2015;Yadav et al. 2021) and are now in the process of testing thisstrain’s survivability and unaltered ability to produce oxygenand biomass under real space conditions at the InternationalSpace Station in frame of the September 2024 ArtEMISSspace flight experiment (Fahrion et al. 2024). Empa and SCKCEN teamed up to study bio-photoelectrochemical cells functionalized with Limnospira indica PCC 8005, funded by theSwiss National Science Foundation and the Flemish ScienceFoundation (Braun et al. 2020).