Algal Research 84 (2024): 103801

https://doi.org/10.1016/j.algal.2024.103801

Space agencies and private companies strive for a permanent human presence on the Moon and ultimately on Mars. Bioprocesses have been advocated as key enablers due to their ability to transform locally available resources into added-value materials. However, the resource-efficiency and scaling of space biosystems remain poorly understood, hindering quantitative estimates of their potential performance. We leveraged extensive cultivation experiments, where a cyanobacterium (Anabaena sp. PCC 7938) was subjected to conditions attainable on Mars, to develop a model that can estimate bioprocess productivity and resource-efficiency as a function of water, light, temperature, regolith minerals and perchlorates, and atmospheric carbon and nitrogen. We show that a breakeven can be reached within a few years. We discuss research lines to improve both resource-efficiency and the accuracy of the model, thereby reducing the need for costly tests in space and eventually leading to a biotechnology-supported, sustained human presence on Mars.

© The Authors ( CC BY 4.0 )

npj Microgravity 10 (2024): 101

https://doi.org/10.1038/s41526-024-00440-1

In situ resource utilization systems based on cyanobacteria could support the sustainability of crewed missions to Mars. However, their resource-efficiency will depend on the extent to which gases from the Martian atmosphere must be processed to support cyanobacterial growth. The main purpose of the present work is to help assess this extent. We therefore start with investigating the impact of changes in atmospheric conditions on the photoautotrophic, diazotrophic growth of the cyanobacterium Anabaena sp. PCC 7938. We show that lowering atmospheric pressure from 1 bar down to 80 hPa, without changing the partial pressures of metabolizable gases, does not reduce growth rates. We also provide equations, analogous to Monod’s, that describe the dependence of growth rates on the partial pressures of CO₂ and N₂. We then outline the relationships between atmospheric pressure and composition, the minimal mass of a photobioreactor’s outer walls (which is dependent on the inner-outer pressure difference), and growth rates. Relying on these relationships, we demonstrate that the structural mass of a photobioreactor can be decreased – without affecting cyanobacterial productivity – by reducing the inner gas pressure. We argue, however, that this reduction would be small next to the equivalent system mass of the cultivation system. A greater impact on resource-efficiency could come from the selection of atmospheric conditions which minimize gas processing requirements while adequately supporting cyanobacterial growth. The data and equations we provide can help identify these conditions.

© 2024, The Author(s)

npj Microgravity  (2024) 

doi: 10.21203/rs.3.rs-4348078/v1

In situ resource utilization systems based on cyanobacteria could support the sustainability of crewed missions to Mars. However, their resource-efficiency will depend on the extent to which gases from the Martian atmosphere must be processed to support cyanobacterial growth. The main purpose of the present work is to help assess this extent. We therefore start with investigating the impact of changes in atmospheric conditions on the photoautotrophic, diazotrophic growth of the cyanobacterium Anabaena sp. PCC 7938. We show that lowering atmospheric pressure from 1 bar down to 80 hPa, without changing the partial pressures of metabolizable gases, does not reduce growth rates. We also provide equations, analogous to Monod's, that describe the dependence of growth rates on the partial pressures of CO2 and N2. We then outline the relationships between atmospheric pressure and composition, the minimal mass of a photobioreactor's outer walls (which is dependent on the inner-outer pressure difference), and growth rates. Relying on these relationships, we demonstrate that the structural mass of a photobioreactor can be decreased – without affecting cyanobacterial productivity – by reducing the inner gas pressure. We argue, however, that this reduction would be small next to the equivalent system mass of the cultivation system. A greater impact on resource-efficiency could come from the selection of atmospheric conditions which minimize gas processing requirements while adequately supporting cyanobacterial growth. The data and equations we provide can help identify these conditions.

© 2024 The Authors, CC BY 4.0

Journal of Environmental Chemical Engineering 12 (2024): 113071  

doi: 10.1016/j.jece.2024.113071

Integrating microbial electrolysis cells (MEC) with anaerobic digestion (AD) would offer different synergistic advantages to these technologies. The MEC bioanode could be immersed in the AD reactor, stabilizing the process, or operated as an independent cell, further removing organic matter. However, up to now, bioanodes operated in anaerobic digestion conditions present low current production and tend to deactivate over time. In the present work, we conducted a comparison of six carbon-based and metal-based electrode materials, including novel options such as stainless steel wool (SSW) and carbon nanofibers (ES300), never tested before under these conditions. The electrodes were evaluated using two inoculation procedures, operating simultaneously in the same electrolyte with different feeding media. The bioanodes produced double the current densities when fed with undigested corn silage compared to anaerobic digester effluent, showing the potential for direct integration into anaerobic digesters without pre-fermentation. Unprecedented stable current densities, up to 0.4 mA cm ⁻² , were obtained over 60 days of operation in real anaerobic digestion conditions by  Geobacter -dominated bioanodes on SSW and ES300, outperforming state-of-the-art bioanodes and avoiding the dramatic deactivation previously reported. Microbial community analysis of SSW and ES300 elucidated how the microbial composition in the bioanodes was mostly depending on the electrode material, rather than the inoculation procedure. The results achieved with these bioanodes pave the way for scaling up and commercializing integrated AD-MEC systems.

© 2024 The Authors, CC BY 4.0, Published by Elsevier Ltd.

Journal of Plant Interactions 19 (2024): 2292220

doi: 10.1080/17429145.2023.2292220

Fresh, nutritious, palatable produce for crew consumption on long-duration spaceflight missions may provide health-promoting, bioavailable nutrients and enhance the dietary experience. VEG-04A and VEG-04B explored growing leafy greens on the International Space Station using the Veggie Vegetable Production System. Two flight tests with ground controls were conducted in 2019 growing mizuna mustard, where veggie chambers were set to different red-to-blue-to-green light formulations. Light quality affects plant growth, nutrition, microbiology, and organoleptic characteristics on Earth, and we examined how these vary in microgravity and under different harvest scenarios. Astronauts harvested and weighed mizuna and completed organoleptic evaluations. Flight samples were returned to Earth for nutritional quality and microbial food safety analyses. Yield and chemistry differed between soil and flight samples and light treatments, and bacterial and fungal counts were lower in soil than in flight samples. This research helps increase our understanding of the requirements for growing high-quality crops in spaceflight.

© 2024, The Authors, CC BY 4.0

npj Microgravity 9 (2024): 81

doi: 10.1038/s41526-023-00329-5

Protecting the Martian environment from contamination with terrestrial microbes is generally seen as essential to the scientific exploration of Mars, especially when it comes to the search for indigenous life. However, while companies and space agencies aim at getting to Mars within ambitious timelines, the state-of-the-art planetary protection measures are only applicable to uncrewed spacecraft. With this paper, we attempt to reconcile these two conflicting goals: the human exploration of Mars and its protection from biological contamination. In our view, the one nominal mission activity that is most prone to introducing terrestrial microbes into the Martian environment is when humans leave their habitat to explore the Martian surface, if one were to use state-of-the-art airlocks. We therefore propose to adapt airlocks specifically to the goals of planetary protection. We suggest a concrete concept for such an adapted airlock, believing that only practical and implementable solutions will be followed by human explorers in the long run.

© 2024, The Authors, CC BY 4.0

52^nd International Conference on Environmental Systems (2023)

 online: https://ttu-ir.tdl.org/bitstream/handle/2346/94682/ICES-2023-258.pdf?sequence=1&isAllowed=y

One of the most important components of a habitat for long-duration missions to Mars is the life support system (LSS), which will most likely include bio-regenerative elements. Since the lives of the crew members depend on the LSS, it is important that they can trust it. Therefore, a human-centered LSS that can be well understood and controlled by the crew is required. In this interdisciplinary work between space engineering, electrical engineering and psychology, the air revitalization component of a human-centered LSS, a photobioreactor (PBR), is being designed. This PBR is integrated into the Moon and Mars Base Analog (MaMBA) facility at the Center of Applied Space Technology and Microgravity (ZARM) in Bremen as part of a future LSS prototype. The PBR, as well as the MaMBA facility, are equipped with multiple sensors which are monitoring various environmental parameters. To provide sensor information to the crew in a preprocessed and user-friendly way, we are designing a graphical user interface (GUI) that can also be used for interaction with the PBR. All three components together, the MaMBA facility, the PBR and the GUI can then be used to test and determine human-factor-related constraints on the operation of a LSS under realistic conditions. This work presents the preliminary design of both the PBR and the GUI and gives first results on the operation of the PBR.

Wireless Networks   2 8  (2022) :  3275-3292

doi: 10.1007/s11276-022-03008-7

Nowadays, the exploitation of Wireless Underground Sensor Networks (WUSNs) remains challenging because of the attenuation of wireless underground communications. This issue widely affects the reliability of communications in such network since the quality of links depends on changing soil conditions. To address this problem, several path loss models have been proposed to predict the attenuation of an electromagnetic wave in soil. However, this prediction has to be done  in-situ  by the sensor nodes themselves so that they can avoid wasting energy when transmissions are not possible due to bad soil conditions. In this paper, we propose a link channel optimization for reliable communications in WUSNs based on Sugeno Fuzzy Inference System (FIS). The proposed approach enables a transmitting node to check whether its environment allows it to reliably send data to a receiver. The proposed FIS consists of 4 inputs, one output and 36 inference rules. The inputs give information on the node's environment, the output gives the probability that data to be sent by a transmitter will be received or not by the receiver. To evaluate the proposed approach, we consider the dataset composed of 140 measurements in dry and moist soil configurations performed at the Cheikh Anta Diop University of Dakar in Senegal. For the validation, we compared our proposal with a recent path loss model called WUSN-PLM according to performance metrics. The results show that our proposal outperforms the WUSN-PLM with higher balanced accuracy (88.21% against 81.061%) and higher Matthews Correlation Coefficient (0.798 against 0.643).

© The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature 2022

44th COSPAR Scientific Assembly. Held 16-24 July, 2022. Online at https://www.cosparathens2022.org/. Abstract F4.1-0012-22.

Bibcode: 2022cosp...44.2840V

To be sustainable, a settlement on Mars should be as independent of Earth as possible in terms of material resources. This independence may be reached with the help of biological systems: those could perform a wide range of functions with a low impact on the surroundings. However, biological systems would best rely on resources available on Mars - as recycling alone would mean that the amounts of available resources decrease over time - and most organisms cannot utilize raw Martian resources directly. Our team in Bremen is developing a system combining cyanobacteria, microbial electrochemical systems (MES) and higher plants to connect bioprocesses to materials available on Mars. In that system, selected cyanobacteria are used as primary producers as they could, it seems, be fed exclusively with materials available on site: water mined from the ground and atmosphere; carbon and nitrogen sourced from the atmosphere (as carbon dioxide and dinitrogen); and metal nutrients present in the local regolith. In addition to the direct production of various consumables, such as dioxygen and dietary proteins, cyanobacteria are here used to support the growth of secondary producers: namely, components of the MES. In the anodic compartment of the MES, organic compounds (from biomass and waste) are oxidized by exoelectrogenic microbes; in the cathodic compartment, electrotrophic microbes are used for the production of various compounds and for perchlorate remediation. Plants are tertiary producers, grown based on effluents from the cyanobacterium and MES modules, and used for the generation of essential resources such as food products, materials, pharmaceuticals and purified water. Our team currently focuses on (i) increasing the abilities of cyanobacteria to grow from Martian resources; (ii) processing their biomass as well as regolith with MES; (iii) integrating plants; and (iv) closing the production-consumption loop. As the foreseen system is versatile and modular, it can be adapted to other bioprocesses, thereby connecting them to local resources. We thus hope to lay the foundation for efficient and sustainable bioproduction on Mars. In that talk, we will present the overall concept and give an overview of the experimental results obtained so far. 

44th COSPAR Scientific Assembly. Held 16-24 July, 2022. Online at https://www.cosparathens2022.org/. Abstract PEX.2-0002-22.

Bibcode: 2022cosp...44.3186A

Leading space agencies have the intention to bring humans to Mars in the next decades, and some private companies push for sooner deadlines. In fact, promises and plans to land humans on Mars have recurrently been announced since the end of the Apollo era, but have remained largely incomplete or even abandoned. At the University of Bremen, we are convinced that human Mars exploration will happen and that it will have a huge impact on both humankind and on the Martian environment. Given that even optimists do not see humans on Mars before the 2030s, we believe that now is the right moment to research possible scenarios for human Mars exploration and settlement, and to study the consequences for Earth, Mars and humankind. To this end, we have formed a new research initiative "Humans on Mars - Pathways to a long-term sustainable human presence" at the University of Bremen. Our approach to human Mars exploration is transdisciplinary and human-centered. On one hand, humankind has experienced tremendous progress and increase in welfare since the Apollo era. On the other hand, we see unambiguously the immense impact of increasing population and welfare on the environmental pollution and associated climate changes. In a nutshell, while the development of new technologies has been the main driver of progress, it has also put Earth in danger. We here argue that human Mars exploration can be instrumental in leading a change from a technology-centered toward a human-centered society, thereby solving our most pressing problems on Earth. Specifically, the thin CO2 Martian atmosphere, the scarcity of energy sources and water, the difficulties to produce food and consumables, and the need for cooperative human-robotic crews, pose challenges whose solutions will enormously benefit Earth. In short, the mindset emerging from thinking under the severe constraints on Mars could be the key to making our presence on Earth sustainable. In this talk, we will present our vision and report on the progress made in selected areas, starting with the shifts in experience and demands on new ways of interaction which come with humankind's expansion to Mars. These include the interactions of the humans on Mars with the humans on Earth on one hand and their habitat and swarm of robots on the other. We will present our efforts in in-situ resource utilization, which focus on sustainable bioproduction, the extraterrestrial fabrication of metal alloys, the production with impure materials and the harvesting of energy from space radiation. 

RSC Advances  12 (2021), 17784-17793

doi: 10.1039/d2ra01162j

Identifying the limiting processes of electroactive biofilms is key to improve the performance of bioelectrochemical systems (BES). For modelling and developing BES, spatial information of transport phenomena and biofilm distribution are required and can be determined by Magnetic Resonance Imaging (MRI) in vivo, in situ and in operando even inside opaque porous electrodes. A custom bioelectrochemical cell was designed that allows MRI measurements with a spatial resolution of 50 μm inside a 500 μm thick porous carbon electrode. The MRI data showed that only a fraction of the electrode pore space is colonized by the Shewanella oneidensis MR-1 biofilm. The maximum biofilm density was observed inside the porous electrode close to the electrode-medium interface. Inside the biofilm, mass transport by diffusion is lowered down to 45% compared to the bulk growth medium. The presented data and the methods can be used for detailed models of bioelectrochemical systems and for the design of improved electrode structures.

© The Royal Society of Chemistry 2022

Advances in Space Research 68 (2021)

doi: https://doi.org/10.1016/j.asr.2021.04.047

Humans are once again preparing to leave Earth and land on the surface of another planetary body. The two objects high on the list for permanent bases are the Moon and Mars. Both have been at the center of attention of many recent spaceflight activities, albeit these have so far been uncrewed. If humans indeed land on either one of them, science can potentially benefit tremendously.

In the past, most spaceflight missions have been implemented by adding scientific instruments after most of the engineering work is already finished. This has often limited scientific studies to relatively scattered, insular topics. However, if prepared appropriately, a research laboratory on either the Moon or Mars can help address scientific questions thoroughly and at a fundamental level.

In this paper we review the main scientific questions relating to the Moon that are still open and develop an overview of the instrumentation that would be necessary for a human astronaut inside a lunar laboratory to help answer these questions. Our primary focus is the Moon, however, we include an outlook to Mars, since we assume that the Moon not only provides a valuable testbed for many technologies to be used on Mars, but that both can be studied with the same habitat laboratory after some specific adaptations.

The research areas we focus on are related to (a) non-living matter (geophysics, geology, materials science), (b) extraterrestrial life (from chemistry of organic carbon compounds to astrobiology), and (c) life inside the human habitat (bioregenerative life-support systems, microbiomes, human physiology). We identify synergies between disciplines, in order to provide a list of priorities to mission planners, and provide a guideline of where further development of equipment would be desirable.

© 2021 COSPAR. Published by Elsevier B.V. All rights reserved.

Frontiers in microbiology12 (2021)

doi:10.3389/fmicb.2021.611798

The leading space agencies aim for crewed missions to Mars in the coming decades. Among the associated challenges is the need to provide astronauts with life-support consumables and, for a Mars exploration program to be sustainable, most of those consumables should be generated on site. Research is being done to achieve this using cyanobacteria: fed from Mars's regolith and atmosphere, they would serve as a basis for biological life-support systems that rely on local materials. Efficiency will largely depend on cyanobacteria's behavior under artificial atmospheres: a compromise is needed between conditions that would be desirable from a purely engineering and logistical standpoint (by being close to conditions found on the Martian surface) and conditions that optimize cyanobacterial productivity. To help identify this compromise, we developed a low-pressure photobioreactor, dubbed Atmos, that can provide tightly regulated atmospheric conditions to nine cultivation chambers. We used it to study the effects of a 96% N₂, 4% CO₂ gas mixture at a total pressure of 100 hPa on Anabaena sp. PCC 7938. We showed that those atmospheric conditions (referred to as MDA-1) can support the vigorous autotrophic, diazotrophic growth of cyanobacteria. We found that MDA-1 did not prevent Anabaena sp. from using an analog of Martian regolith (MGS-1) as a nutrient source. Finally, we demonstrated that cyanobacterial biomass grown under MDA-1 could be used for feeding secondary consumers (here, the heterotrophic bacterium E. coli W). Taken as a whole, our results suggest that a mixture of gases extracted from the Martian atmosphere, brought to approximately one tenth of Earth's pressure at sea level, would be suitable for photobioreactor modules of cyanobacterium-based life-support systems. This finding could greatly enhance the viability of such systems on Mars.

 © 2021 Verseux, Heinicke, Ramalho, Determann, Duckhorn, Smagin and Avila. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY)

Frontiers in Plant Science  11 (2020)

doi: 10.3389/fpls.2020.00656.

The EDEN ISS greenhouse is a space-analog test facility near the German Neumayer III station in Antarctica. The facility is part of the project of the same name and was designed and built starting from March 2015 and eventually deployed in Antarctica in January 2018. The nominal operation of the greenhouse started on February 7th and continued until the 20th of November. The purpose of the facility is to enable multidisciplinary research on topics related to future plant cultivation on human space exploration missions. Research on food quality and safety, plant health monitoring, microbiology, system validation, human factors and horticultural sciences was conducted. Part of the latter is the determination of the biomass production of the different crops. The data on this topic is presented in this paper. During the first season 26 different crops were grown on the 12.5 m² cultivation area of the greenhouse. A large number of crops were grown continuously throughout the 9 months of operation, but there were also crops that were only grown a few times for test purposes. The focus of this season was on growing lettuce, leafy greens and fresh vegetables. In total more than 268 kg of edible biomass was produced by the EDEN ISS greenhouse facility in 2018. Most of the harvest was cucumbers (67 kg), lettuces (56 kg), leafy greens (49 kg), and tomatoes (50 kg) complemented with smaller amounts of herbs (12 kg), radish (8 kg), and kohlrabi (19 kg). The environmental set points for the crops were 330–600 μmol/(m^2*s) LED light, 21°C, ∼65% relative humidity, 1000 ppm and the photoperiod was 17 h per day. The overall yearly productivity of the EDEN ISS greenhouse in 2018 was 27.4 kg/m², which is equal to 0.075 kg/(m^2*d). This paper shows in detail the data on edible and inedible biomass production of each crop grown in the EDEN ISS greenhouse in Antarctica during the 2018 season.