Synergetic Material Utilization – Combining ISRU and ECLSS

Introduction: Sustaining exploration of the solar system requires a large amount of material and an even larger amount of propellant to transport this material out of Earth’s gravity well and onwards to its destination. Despite recent advances in lowering the launch costs by applying methods such as reusability of the launch system, transferring material from Earth to space is still very costly with several thousand to tens of thousands Euro per kilogram into a low-earth orbit and transportation to Moon and Mars cost-ing a multitude of that. Although, current predictions foresee a further reduction in launch costs in the near future to tens of Euro per kilogram, each kilogram of material transported from Earth to LEO remains valuable and when transported to Moon or Mars the value is even higher. Human space exploration requires a significant amount of resources such as food, water and oxygen. Waste products such as metabolic waste, polluted water and carbon dioxide are produced by the astronauts. Life support engineers are developing systems and processes to recycle and to regenerate as many resources as possible, also known as ‘closing the loops’, in order to reduce the material supplied from Earth to enable sustainable human space exploration of the solar system. Our solar system is full of resources that potentially can be exploited to greatly reduce the material required to be launched from Earth. Among these resources are water ice, hydrates, metals, regolith, rare earths, chemical compounds, volatiles and rare isotopes. Utilizing space resources would enable e.g. propellant production, in-space manufacturing or the construction of large structures which would otherwise be very expensive or not possible at all with material launched from Earth. The concept of Synergetic Material Utilization (SMU) combines In-situ Space Resources Utilization (ISRU) and Environmental Control and Life Support System (ECLSS) engineering approaches to lower the material supply required from Earth. In 2021 a research group was founded at the German Aerospace Center’s Institute of Space Systems in Bremen, which focuses on the Synergetic Material Utilization concept. Synergetic Material Utilization Concept: ECLSS and SRU are two space engineering fields with increasing importance in the future to enable sustainable exploration of the solar system. In both fields processes and techniques are applied to ex-tract, produce, utilize, consume and regenerate resources albeit with different purposes. The goal of ECLSS engineering is to enable human survival in space with as little resources as possible in order to reduce cost for resupply from Earth. SRU on the other hand uses local resources to produce a wide range of materials for different applications, but also with the goal of reducing the cost of launching the material from Earth. Despite the similarities among both fields, ECLSS and SRU scientists and engineers often disregard the other research field. Almost all case studies of near-term SRU rely purely on robotics and automation without the assistance of humans on-site. Often the presence of humans is rejected with the argument regarding the costs involved of setting up the required ECLSS infrastructure. ECLSS case studies of future Moon or Mars space exploration systems, on the other hand, mostly neglect the utilization of local resources because of the fixation on regeneration and the ‘closing the loop’ principle, but also by using the cost argument for setting up a SRU infrastructure. Synergetic Material Utilization is the approach of combining ECLSS and SRU engineering in order to exploit the many synergies among both fields to enable sustainable exploration of the solar system. Synergies between ECLSS and SRU are: Shared processes and technologies, Common materials processed, Common products generated, Cross-utilization of products and resources, Combination of materials from various sources. Planned Activities of the SMU Research Group at DLR: The SMU research group at the DLR Institute of Space Systems was established in 2021 with approval of the Director of Space Research of DLR. This research group focuses on the combination of SRU technologies with life support systems and processes in order to exploit synergies. Thus, a holistic approach for resources management during future space exploration missions is persecuted. Concrete activities for the next 3-4 years are technology developments for regolith beneficiation, oxygen extraction from regolith and water extraction for in-situ propellant production. These developments are complemented by a system study for a shared water-hydrogen-oxygen infrastructure with ISRU and ECLSS elements for a future habitat and by concept studies for the in-situ production of new materials based on ISRU and ECLSS products. The schematic below illustrates how the different topics of the research group are connected to each other and also where the interfaces with the ECLSS and habitat are

Influence of crop cultivation conditions on space greenhouse equivalent system mass

Future crewed space missions will make use of hybrid life support systems to sustain human presence in space and on other planetary bodies. Plants fulfll essential roles in those systems such as carbon dioxide removal, oxygen production, and food production. The systems required to grow plants in space, so-called space greenhouses, are complex and need to be built as efcient as possible. Thereby, the resources mass, volume, energy, and crewtime required to grow a certain amount of food are essential because these parameters defne the efectiveness of the space greenhouse. However, the required resources depend on the size of the greenhouse which in turn depends on the productivity of the crops which in turn depend on the cultivation conditions. The output of such a system can be calculated using the Modifed Energy Cascade plant production model, which can simulate the food output depending on the cultivation conditions. Traditionally, life support systems are evaluated using the Equivalent System Mass method, which can determine the cost efective life support architecture for a given mission scenario. By combining both, the infuence of the cultivation conditions inside the space greenhouse on the efectiveness of the complete system can be investigated. It seems counterintuitive frst, but it is more efective to increase the energy per area provided to the plants in the form of light. Although that increases the electrical energy demand per area, the reduction in required cultivation area and, therefore, system size leads to a more efcient system

Effects on ECLSS Behavior caused by the Start-up of a Food Production Facility

In the next decades humans will take on the challenges of venturing to the Moon, Mars and other planetary bodies in our solar system. The farther out and the longer the crewed missions get, the more effective is recycling of resource to provide life support for the humans travelling. One aspect is the production of food on-site during the mission to greatly reduce the resupply need from Earth. The cultivation of plants hereby is the preferred way. Plants do not only provide a large variety of food, but also consume the carbon dioxide exhaled by the crew and produce oxygen. The cultivation of plants in a closed environment is challenging, but recent experiments on Earth and on-board the ISS have shown the feasibility of such a system. Another aspect of plant cultivation in a crewed spacecraft or habitat is the influence of the crops on the ECLSS. Food production is only possible, when the plants are provided with the resources and environment necessary to thrive. Providing these resources in sustainable way means that the greenhouse subsystems are interconnected with the ECLSS. Consequently, the cultivation of plants has, depending on the amount of crops grown, a significant impact on the ECLSS (e.g. on the dimension of certain systems like the water recycling). This paper presents the results of a dynamic simulation of an ECLSS with an integrated greenhouse for crop cultivation. The focus lies on the start-up phase of this facility, because until the steady-state production is reached the impact of the greenhouse on the ECLSS is changing constantly and therefore the ECLSS has to cope with that. The simulations show that the startup of the greenhouse after the crew arrival with staggered sowing performs best, because this scenario has the best system behavior and does not need additional automation equipment and procedures for sowing and harvesting

An investigation of the dynamic behavior of a hybrid life support system and an experiment on plant cultivation with a urine-derived nutrient solution

Earth’s biosphere is sustained by its biological diversity, which forms an intricate network of biological, physical and chemical pathways. This network has many fail-safe redundant func-tions including buffer stocks of inert biomass, huge amounts of water and the large volume of gases in the atmosphere. By contrast, manmade habitats for human space exploration are closed ecosystems that represent only a trivial fraction of Earth’s biosphere. The employment of bio-regenerative processes complemented with physical-chemical tech-nologies is thought to have numerous advantages from the perspective of redundancy and reducing resupply mass for the sustained human presence in space or on other planetary surfaces. However, the combination of bio-regenerative processes, such as plant cultivation, with physical-chemical processes to form hybrid life support systems is challenging. Such systems are a concert of many interdependencies and interacting feedback loops, which are difficult to operate in a desired range of set points. Furthermore, the complexity of such sys-tems makes them vulnerable to perturbations. Applying system dynamics modelling to study hybrid life support systems is a promising ap-proach. System dynamics is a methodology used to study the dynamic behavior of complex systems and how such systems can be defended against, or made to benefit from, the per-turbations that fall upon them. This thesis describes the development of a system dynamics model to run exploratory simulations, which can lead to new insights into the complex behav-ior of hybrid life support systems. An improved understanding of the overall system behavior also helps to develop sustainable, reliable and resilient life support architectures for future human space exploration. A set of simulations with a hybrid life support system integrated into a Mars habitat has been executed and the results show a strong impact of space greenhouses on the life support sys-tem behavior and the different matter flows. It is also evident from the simulation results that a hybrid life support system can recover from a perturbation event in most cases without a fatal mission end. Recycling urine to produce a plant nutrient solution is a novel approach in further closing loops in space life support systems. Within this thesis, a number of experiments have been executed in order to determine the effectiveness of a urine-derived nutrient solution com-pared to a standard reference solution. The results show that in principle plants can be grown with a nutrient solution made of human urine, but that the yield is lower compared to the reference solution. However, the urine-derived solution might be tuned by adding small amounts of additional nutrients to remove the imbalance of certain elements. This way the nutrient salts supplied from Earth could be reduced

Radar and Snow Structure Studies in the Percolation Zone of the Greenland Ice Sheet: A Data Report on the 1993 Field Season at Dye-2

From June 18 to July 12, 1993, a Byrd Polar Research Center team undertook radar and snow physical properties studies near Dye-2, in the percolation zone of Greenland's ice sheet. These studies were intended to advance our understanding of the microwave scattering properties of the ice sheet, in order to better interpret satellite remote sensing signals for mass balance and climate studies. This report summarizes the experiments performed and the data collected. Table I summarizes a list of our measurement objectives. In general terms, our work at Dye-2 consisted of making radar observations of the snow at Ku-band (13.5 GHz) and a variety of incidence angles. The radar frequency is the same as that of the radar altimeter aboard the ERS-1 satellite. In conjunction with the radar observations, we dug pits in the snow and recorded physical properties such as snow stratigraphy, density, and grain sizes. In section 2 we present a map of the camp and experiment sites. In sections 3 and 4 we describe the pit and radar studies in detail. Finally, section 5 is a detailed chronology of the field season

Biomass Production of the EDEN ISS Space Greenhouse in Antarctica During the 2018 Experiment Phase

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/(m2∗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/(m2∗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

Experimental Demonstration of Lunar Water Extraction and Purification

Sustainable space exploration requires the development of In-Situ Resource Utilization (ISRU) technologies, which encompass all processes that utilize local resources to generate useful products for robotic and human exploration. Among the available resources, water is the most versatile and most needed in space exploration. Water can be directly used as consumable for astronauts or electrolyzed to hydrogen and oxygen, a very effective rocket propellant combination. However, in-situ water extraction is challenging and the required technologies are not yet fully developed. The LUWEX project focuses on the development and validation of a complete in-situ water process chain including water extraction, purification and quality monitoring. An integrated test setup was built to validate the operational capabilities of these technologies and also of the whole process chain. This setup delivers a relatively realistic environment analogue to the lunar surface and uses a lunar dust-ice simulant to provide proper validation conditions. The goal of the experiments is to demonstrate the extraction and purification of one liter of water. The project team is going to present the first experiment results of the LUWEX project which will enable future water extraction an purification for consumables and propellant production on the Moon

Service Section Design of the EDEN ISS Project

The international EDEN ISS project aims to investigate and validate techniques for plant cultivation in future bioregenerative life support systems. To this end the EDEN ISS project partners aim to design and build the Mobile Test Facility, which consists of two modified 20 foot shipping containers. One of these shipping containers is designated the Service Section and houses the bulk of the subsystem components, such as the Air Management System and Nutrient Delivery System, as well as a rack-sized plant cultivation system, which uses a standard International Space Station payload form factor. The subsystems within the Service Section ensure that the approximately 12.5 m² of cultivation area in the second container, the Future Exploration Greenhouse, have the proper environmental conditions, nutrients and illumination for optimal crop growth. The EDEN ISS project concluded its main design phase with a Critical Design Review in March 2016, thereafter proceeded into the hardware development and procurement phase of the project. This paper describes the final design of the Service Section at the start of the assembly, integration and testing phase, which will run until the complete Mobile Test Facility is shipped to Antarctica, where it arrives in December 2017, for a 12 month space analogue mission

Experimental optimisation of lunar regolith beneficiation for the production of an Ilmenite-rich feedstock

The space industry is moving towards increasing sustainability for operations of a long duration space mission and eventually a permanent space settlement. In-situ resource utilization (ISRU) technologies will play a major role in realizing this vision. As moon is the current object of interest, the lunar regolith becomes the most abundantly available source of different minerals on the lunar surface. One such mineral is Ilmenite which is an ore of titanium as well as a source for oxygen. Previous research shows that Ilmenite is a more energy efficient source for extraction of oxygen compared to other minerals such as silicates. However, Ilmenite deposits on the lunar surface are scattered and not as high as the silicate minerals

Summary and Evaluation of the EDEN ISS Public Outreach Activities

EDEN ISS is a European project focused on advancing bio-regenerative life support systems, in particular plant cultivation in space. A mobile test facility was designed and built between March 2015 and October 2017. The facility incorporates a Service Section which houses several subsystems necessary for plant cultivation and the Future Exploration Greenhouse. The latter is built similar to a future space greenhouse and provides a fully controlled environment for plant cultivation. The facility was setup in Antarctica in January 2018 and successfully operated between February and November of the same year. During that nine month period around 270 kg of food was produced by the crops cultivation in the greenhouse. It is the wish and more often the need for scientific projects to communicate their outcomes not only to the scientific community, but also to the general public. The EDEN ISS project and in particular the experimental phase in Antarctica was accompanied by extensive public outreach activities. Presence in social media, a project website, informative flyers, an experimental toolkit for young students were created in order to engage with the general public. This paper describes the different public outreach activities of the project and also evaluates their effectiveness. For the evaluation, statistics from the website and social media accounts as well as responses to press releases and educational activities are being displayed. Based on the experience from the outreach campaign of EDEN ISS, the paper provides recommendations on how to organize and conduct public outreach activities for scientific projects in space exploratio