Browsing by Author "Belz, Stefan"

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Design of a test platform for algae cultivation research at different gravitation levels
(48th International Conference on Environmental Systems, 2018-07-08) Detrell, Gisela; Belz, Stefan; Bretschneider, Jens; Kittang Jost, Ann-Iren; Mejdell Jakobsen, Øyvind
As a contribution to closed regenerative life support systems for future space exploration, the EU Horizon 2020 project TIME SCALE develops an advanced life support system concept to allow life science research and technology demonstrations under fractional gravity conditions. The project is based on the European Modular Cultivation System (EMCS), an experiment platform to study biology and perform technology demonstrations at different gravitation levels (e.g. lunar gravity), and develops concepts and hardware with applicability for both payloads on the International Space Station and for life support systems beyond. The project is carried out in the frame of Horizon 2020 by eight European consortium partners: Norges Teknisk-Naturvitenskapelige Universitet (NTNU), Wageningen University, Universiteit Gent, Universität Stuttgart, Design and Technologies for High Performance Mechanics (DTM), Interscience Belgium/Netherlands, Prototech AS, Cleangrow LTD. This paper presents the concept developed by the University of Stuttgart for an Algae Cultivation Compartment (ACC). Two major designs are proposed: a technology demonstrator and a fundamental biology research platform. The technology demonstrator design includes powerful lighting, temperature control, gas supply and a water-nutrient-management system. The aim of this system is to grow biomass fast, allowing for a systemic assessment focused on gas-turnover rates and growth speed, allowing a quick comparison of different bioreactor designs, upstream procedures, nutrient compositions, and algae species at the target gravity level. The biology research platform contains several cassettes including agar plates for algae growth. The goal is the investigation of single algae cells in a strictly controlled environment, allowing for fundamental research, investigating direct correlations between growth conditions (e.g. lighting spectrum, gas composition) and cell expression. Every cell cluster is separately illuminated, and each test chamber can operate with a different gas composition.
Efficient Evaluation Method of System Concepts for Preliminary ECLSS Design Studies
(44th International Conference on Environmental Systems, 2014-07-13) Binder, Tilman; Nathanson, Emil; Belz, Stefan; Fasoulas, Stefanos
The concept trade-off is a crucial step in the conceptual design of environmental control and life support systems (ECLSS). For this purpose, a computer program is developed by which a large number of options can be evaluated efficiently using parameter variation. The tool enables an automatic preliminary design of a complete ECLSS for time-averaged operation, and has proven to be a good supplement to discrete-time simulations. It is divided into two calculation parts. The first calculation balances mass flow rates of individual ECLSS components for time-averaged operation and is realized in a Microsoft Excel® spreadsheet file. The second calculation performs an iterative parameter variation in MATLAB®. Additionally to the variation of different component configurations, further parameters are optimized in terms of minimizing the equivalent system mass (ESM). These parameters include the amount of oxygen produced by water electrolysis and the operating levels of waste water regeneration and carbon dioxide reduction components. The algorithm is based on nested loops for the variation of the individual parameters and checking on linear dependencies or, alternatively, the bisection method for ESM optimization. The tool is demonstrated for an innovative free flyer concept in cis-lunar space. For the considered station, 160 different physicochemical configurations are evaluated.
ELISSA – a Comprehensive Software Package for ECLSS Technology Selection, Modelling and Simulation for Human Spaceflight Missions
(47th International Conference on Environmental Systems, 2017-07-16) Detrell, Gisela; Belz, Stefan
The software tool ELISSA (Environment for Life-Support Systems Simulation and Analysis) is being developed at the Institute of Space Systems (IRS), University of Stuttgart since the mid-90s and allows the analysis and validation of new ECLSS designs, as well as system optimization. The time-discrete simulation tool offers a wide library of both physico-chemical and biological components for air, water, food and waste management, with special focus on potential components for future long duration missions. The components have been modeled, depending on their Technology Readiness Level (TRL) and current available reference data, either from specifications of existing technologies, experimental data or from physical/chemical fundamentals from the literature. As a result, some components are model as a detailed dynamic process, whereas others are represented as a static process. The ELISSA components library is constantly being updated with new components data, including real data from experiments, for example from the photobioreactor experiment currently being developed at IRS. The ELISSA user can select the components to be used for each ECLSS model and simulation as well as other mission specific parameters such as size of the crew, mission duration, initial consumables or tank sizes, through a user-friendly interface. The simulation results show the behavior of the system over the mission time, allowing to properly size the components, tanks and consumables for a specific mission. ELISSA provides the Equivalent System Mass (ESM) in order to compare different ECLSS designs. To complement ELISSA, two other tools have been developed: PrELISSA, which enables the comparison of a large number of components combinations for a first model design selection and Reliability ELISSA, which allows the evaluation of the reliability at different system levels considering the use of spare parts. The entire ECLSS reliability is the result of a complex time-discrete stochastic simulation.
The final configuration of the algae-based ISS experiment PBR@LSR
(48th International Conference on Environmental Systems, 2018-07-08) Keppler, Jochen; Belz, Stefan; Detrell, Gisela; Helisch, Harald; Martin, Johannes; Henn, Norbert; Fasoulas, Stefanos; Ewald, Reinhold; Angerer, Oliver; Hartstein, Heinz
The spaceflight experiment PBR@LSR (Photobioreactor at the Life Support Rack) shall demonstrate the technology and performance of a hybrid life support system under real space conditions during an operation of half a year. To be launched to the International Space Station (ISS) in 2018, PBR@LSR combines a microalgae photobioreactor (PBR) and the carbon dioxide (CO2) concentrator of ESA’s Life Support Rack (LSR), also known as the European ACLS. Accommodated in the Destiny module, LSR will absorb and concentrate CO2 out of the cabin atmosphere. A dedicated interface allows the utilization of highly concentrated surplus CO2 for cultivation of microalgae in the PBR. The microalgae species Chlorella vulgaris uses CO2 to conduct photosynthesis. Biomass is produced and oxygen (O2 ) is released. Besides this technical approach of a hybrid life support system, PBR@LSR also pursues scientific goals: stability and performance of a non-axenic long-term cultivation in the µg-adapted PBR as well as on-ground analyses of returned microalgae samples. This paper highlights different subsystems of the spaceflight experiment PBR@LSR in the final configuration, especially the algae suspension loop, lighting, gas handling, humidity control, liquid exchange. Within the different subsystems, the selection of critical components is explained. The overall system design is verified with experimental data.
From Breadboard to Protoflight Model – the Ongoing Development of the Algae-Based ISS Experiment PBR@LRS
(47th International Conference on Environmental Systems, 2017-07-16) Keppler, Jochen; Helisch, Harald; Belz, Stefan; Bretschneider, Jens; Detrell, Gisela; Henn, Norbert; Fasoulas, Stefanos; Ewald, Reinhold; Angerer, Oliver; Adrian, Astrid
Hybrid life support systems are of great interest for future and far-distant space exploration missions e.g. manned missions to near earth objects (NEOs) or planetary surfaces. By combining physicochemical and biological algae-based subsystems, an essential step towards the closure of the carbon loop in life support systems (LSS) is accomplished, offering a wide potential of benefit for LSS through the utilization of photosynthesis. Oxygen and edible biomass can be formed from carbon dioxide and water aboard the space vessel. The DLR technology experiment PBR@LSR (Photobioreactor at the Life Support Rack) is set to give a first technology and performance demonstration of hybrid life support system technologies aboard the ISS in the Destiny module in 2018. An algae-based photobioreactor (PBR) is used for the cultivation of Chlorella vulgaris and is combined with the carbon dioxide concentrator of ESA´s Advanced Closed Loop System (LSR) built by Airbus DS. This paper shows the development process of PBR@LSR from the breadboard phase towards the protoflight model (PFM). Biological testing focuses on the influence of thermal cycle dependencies on algae growth. Ground-based experiments focus on the stability, the performance and the operational handling of the long-term cultivation of C.vulgaris in the µg adapted setup. A number of long-term test data on different cultivation cycles and proposals for the ongoing development of the experiment setup are presented.
Functionality and setup of the algae based ISS experiment PBR@LSR
(46th International Conference on Environmental Systems, 2016-07-10) Bretschneider, Jens; Henn, Norbert; Belz, Stefan; Detrell, Gisela; Keppler, Jochen; Fasoulas, Stefanos; Kern, Peter; Helisch, Harald
Hybrid life support systems combining physicochemical and biological algae based subsystems are in great interest for the midterm future of manned spaceflight including extensive ground missions on Moon and Mars. Whereas many possible systems have been theorized and tested in laboratory conditions, no experiments on realistic system level have been performed in space. The DLR experiment PBR@LSR (Photobioreactor at the Life Support Rack, former name PBR@ACLS) is set to give a first technology and performance demonstration on board the ISS in the Destiny module in 2018 by combining an algae based photobioreactor with the carbon dioxide concentrator of ESA’s Advanced Closed Loop System built by Airbus DS. This paper shows the design process of the ongoing flight hardware development. The prototype design is detailed in conjunction with the operational requirements, safety limitations and scientific needs. The connection to the carbon dioxide concentrator enables the use of carbon dioxide from the cabin. The algae medium loop consists of different components of specific functionalities (pumping, illumination, nutrient supply, temperature control, etc.) to allow cultivation of the microalgae Chlorella vulgaris. The progress of ground experiments is presented and the derived decisions for the system design and setting parameters are explained. The paper concludes with an overview of reached and open milestones to the flight design of PBR@LSR.
Innovative Biological and Physico-Chemical Recycling of CO2 in Human Spaceflight
(47th International Conference on Environmental Systems, 2017-07-16) Belz, Stefan; Keppler, Jochen; Bretschneider, Jens; Helisch, Harald; Detrell, Gisela
Human spaceflight beyond Low Earth Orbit requires recycling technologies to handle consumables and waste. State-of-the-art technologies on the ISS are based on physico-chemical processes and enable atmosphere control, water regeneration, carbon dioxide (CO2) removal and reduction. Food is completely provided by resupply. Physico-chemical CO2 treatment means concentration by adsorption and reduction by the Sabatier (or Bosch) process. The next technological step to recycle CO2 is the testing and implementation of biological systems. Especially microalgae based systems can offer an innovative approach to meet the space requirements. Based on photosynthesis, microalgae generate edible biomass from CO2 and release oxygen. An innovative approach is to connect the CO2 photobioreactor inlet with the outlet of a CO2 concentration unit. This is one focus of the spaceflight experiment PBR@LSR prepared by DLR, Airbus DS and the University of Stuttgart. Cultivation in aquatic reservoirs (photobioreactors) reaches up to ten time higher growth rates and lower energy and volume investments than higher plants. Hydroponic basis or soils are not needed. The species Chlorella vulgaris is a promising candidate among a multitude of microalgae species. It is rich in proteins, thus up to 30% of human food needs can be covered by algae biomass. Harvesting and downstream processing of liquid algae medium are engineering issues under micro to partial gravity. An appropriate technology to break the cell wall, such as ultra-sonic handling and cross-flow filtration, depends on the gravity level and space system boundaries. Another innovative physico-chemical technology reducing CO2 is solid oxide electrolysis. It will be useful to treat CO2 in the Martian atmosphere. Crucial components are stable electrode materials not poisoned by carbon monoxide. Requirements, boundaries of biological and physico-chemical recycling technologies are summarized.
Non-axenic microalgae cultivation in space – Challenges for the membrane µgPBR of the ISS experiment PBR@LSR
(48th International Conference on Environmental Systems, 2018-07-08) Helisch, Harald; Belz, Stefan; Keppler, Jochen; Detrell, Gisela; Henn, Norbert; Fasoulas, Stefanos; Ewald, Reinhold; Angerer, Oliver
The spaceflight experiment PBR@LSR (Photobioreactor at the Life Support Rack) shall demonstrate for the first time the technology and performance of a hybrid life support system – a combination of physico-chemical and biotechnological components – under real space conditions during an operation period of 180 days. To be launched to the International Space Station (ISS) in 2018, PBR@LSR combines the carbon dioxide (CO2) concentrator of ESA’s Life Support Rack (LSR) with an advanced microalgae photobioreactor (PBR). Accommodated in the Destiny module, LSR will concentrate CO2 from the cabin atmosphere. A dedicated interface allows the utilization of the highly concentrated surplus CO2 for the cultivation of the green microalgae species Chlorella vulgaris. Current research at the University of Stuttgart focuses on the fundamental investigation and optimization of non-axenic cultivation processes in µg capable membrane PBRs. This includes the characterization of influences of accompanying bacteria on the non-axenic microalgae culture stability within the PBR suspension loop, photosynthetic capacity as well as overall biomass composition. This paper discusses in general possible influences of emerging bacteria-induced biofilm formation and cell clustering due to non-axenic processing on the long term functionality of µg adapted PBR systems, e.g. PBR@LSR.
Preparatory ground-based experiments on cultivation of Chlorella vulgaris for the ISS experiment PBR@LSR
(46th International Conference on Environmental Systems, 2016-07-10) Helisch, Harald; Keppler, Jochen; Bretschneider, Jens; Belz, Stefan; Henn, Norbert; Fasoulas, Stefanos; Kern, Peter
Hybrid life support systems combining physicochemical and biological subsystems are in great interest for the midterm future of manned spaceflight including extensive basic habitation LSS research on ground exploration missions on Moon and Mars. While many possible systems have been theorized and tested in lab conditions, no experiments on realistic system level have been performed in space. The DLR experiment PBR@LSR (Photobioreactor at the Life Support Rack) (former name PBR@ACLS) is set to give a first technology and performance demonstration on board the ISS in the U.S. module Destiny in 2018 by combining an microalgae driven photobioreactor with the carbon dioxide concentrator of ESA’s Advanced Closed Loop System built by Airbus DS. This paper focuses on cultivation aspects of the ongoing preparations for the flight experiment. These ground-based experiments include several experiment runs with the microalgae Chlorella vulgaris with durations up to 25 days in a complete closed loop photo-bioreactor prototype and additional small scale experiments for pre-cultivation storage and post cultivation control of the C. vulgaris suspension. The cultivation requires a sensitive setting of parameters to sustain an environment for microalgae growth such as illumination, nutrients, temperature, etc. to aim for long-term period cultivation of up to 180 days. The paper concludes with recommendations for PBR@LSR to enable an improved cultivation.