Frontiers in Space Technologies最新文献

{"title":"Verification of a virtual lunar regolith simulant","authors":"Joe Louca, J. Vrublevskis, Kerstin Eder, Antonia Tzemanaki","doi":"10.3389/frspt.2024.1303964","DOIUrl":"https://doi.org/10.3389/frspt.2024.1303964","url":null,"abstract":"Introduction: Physical regolith simulants are valuable tools for developing In-Situ Resource Utilisation hardware. However, using virtual models of regolith instead can reduce costs, limit exposure to hazardous materials, and offer a practical method of testing the effects of reduced gravity.Methods: We verify a virtual model of regolith as macroparticles against physical tests. Using space partitioning techniques to identify neighbouring particles, we present a scalable model of regolith, in which the computation time increases roughly proportionally with the number of particles. We evaluated the performance of this virtual simulant vs. a physical simulant (Exolith LMS-1) by comparing the flow rate through funnels of various diameters, and the resultant angle of repose of material on both large (500 g) and small (16 g) scale tests.Results: For large scale tests, the flow rates were within the predicted range for macroparticles with radii 3–7 mm, with the greatest accuracy achieved for radii 4–5 mm. However, the macroparticles blocked the simulated funnels more easily than in the physical trials, due to their high cohesion. The angle of repose was not accurately represented by this model for either of the tests.Discussion: The high efficiency of this model makes it best suited for applications which require large scale approximations of regolith with real-time execution, such as virtual training for robot operators or providing visual and haptic feedback in model-mediated teleoperation systems. The results of this model in reduced gravity could be further verified against data from upcoming lunar missions in future work.","PeriodicalId":137674,"journal":{"name":"Frontiers in Space Technologies","volume":"18 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140439064","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optimizing lunar regolith beneficiation for ilmenite enrichment","authors":"Kunal Kulkarni, Michel Fabien Franke, Muchammad Izzuddin Jundullah Hanafi, Thorsten M. Gesing, Paul Zabel","doi":"10.3389/frspt.2023.1328341","DOIUrl":"https://doi.org/10.3389/frspt.2023.1328341","url":null,"abstract":"Over the past few years, the international space industry has focused extensively on advancing technologies to enable prolonged human space exploration missions. The primary limiting factor for these endeavors is the spacecraft’s capacity to transport and store essential supplies from Earth to support human life and mission equipment throughout the mission’s duration. In-situ resource utilization (ISRU) is the preferred solution for this challenge. Previous lunar missions have identified the presence of oxygen within the lunar regolith, which is an important resource for human space exploration missions. Oxygen is present in many different minerals within the lunar regolith out of which, ilmenite provides the highest yield of oxygen per unit mass using hydrogen reduction. However, the distribution of ilmenite is neither high nor uniform throughout the lunar surface and therefore, needs beneficiation, which is an important intermediate step for ilmenite-based oxygen production. A regolith beneficiation testbed was developed at DLR Bremen which is a TRL 4 level representation of the technology. The testbed has multiple process parameters that can be adjusted to produce the desired feedstock. This work focuses on the optimization of this testbed to produce a feedstock with higher ilmenite content than the input regolith. The testbed comprises three beneficiation techniques, viz. gravitational, magnetic and electrostatic beneficiation that work sequentially to produce the desired feedstock. The optimized parameter configuration achieved up to three-fold increase in the ilmenite grade relative to the input with about 32 wt% of the total ilmenite being recovered in the enriched output. These experiments have highlighted other underlying factors that influenced the experimental research such as the design of testbed components, system residuals and limited availability for Off-the-shelf components. The observations made from these experiments have also provided insights into the further development of the technology. The work has thus produced evidence for the effectiveness of the beneficiation testbed in producing an enriched feedstock while outlining avenues for future improvements.","PeriodicalId":137674,"journal":{"name":"Frontiers in Space Technologies","volume":" 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139624368","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Phenotypical changes in Escherichia coli K12 after prolonged exposure to simulated microgravity","authors":"A. Chavez, Collin Topolski, Janelle Hicks, Mitchell Villafania, Natalie Baez, Marissa Burke, Hugo A. Castillo","doi":"10.3389/frspt.2023.1282850","DOIUrl":"https://doi.org/10.3389/frspt.2023.1282850","url":null,"abstract":"Over the past few decades there has been a steady increase in interest in the study of the role of space environment in the genetic and phenotypical changes of microorganisms. More specifically, there are concerns with astronaut health being compromised during missions to the Moon and beyond from changes in many conditions. These include changes in the physiology of bacteria leading to alterations directly related to human health such as virulence and antibiotic resistance or to the functioning of life support systems such as the increase in biofilm formation in the water supply or treatment components. The effects of space conditions on microorganisms have been studied for more than a decade; however, there is still a need to determine the impact of the physiological effect of microgravity not only of bacterial growth, but also on the different virulence-related phenotypes that might contribute to phenotypic plasticity and microbial adaptation. This study focuses on deciphering the phenotypical changes of the commensal bacterium E. coli K12 after growth under simulated microgravity conditions using a 2D microgravity analog. Using a 2D clinostat, Escherichia coli was grown up to 22 days and used to measure changes in phenotypes commonly related to virulence. The phenotypes measured included cell population growth, biofilm development and the response to acidic pH and oxidative stress. Results from our studies showed the tendency to enhanced biofilm formation and a decreased resistance to oxidative stress and to grow under acidic conditions. These results suggest that microgravity regulates the adaptation and phenotypic plasticity of E. coli that could lead to changes in virulence.","PeriodicalId":137674,"journal":{"name":"Frontiers in Space Technologies","volume":"42 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139441090","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Permittivity sensor development for lunar and planetary surface exploration","authors":"C. Gscheidle, Thilo Witzel, Alexander Smolka, Philipp Reiss","doi":"10.3389/frspt.2023.1303180","DOIUrl":"https://doi.org/10.3389/frspt.2023.1303180","url":null,"abstract":"Permittivity sensors measure the electric permittivity (formerly known as the dielectric constant) of a sample between its electrodes and offer a reliable method to characterize the subsurface of planetary bodies in situ. One potential application is the identification and mapping of water ice at the poles of the Moon. In this paper, the scientific background and heritage of the permittivity sensor concept are discussed, and the implemented electronic architecture is introduced, focusing on the novel patch electrodes. The data processing approach for the measurements is based on Fourier transformation, and numerical simulation setups are used for performance predictions. The calibration of the sensor validates the functionality of the electronics, and the results from both simulations and characterization experiments show that the concept is applicable in the exploration scenario. Considering both engineering and scientific aspects, the results highlight the permittivity sensor’s suitability for lunar and planetary exploration missions, albeit further points for improvement are identified.","PeriodicalId":137674,"journal":{"name":"Frontiers in Space Technologies","volume":"35 8","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139441448","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Bacillus subtilis engineered for aerospace medicine: a platform for on-demand production of pharmaceutical peptides","authors":"Alec Vallota-Eastman, Cynthia Bui, Philip M. Williams, David L. Valentine, David Loftus, Lynn Rothschild","doi":"10.3389/frspt.2023.1181843","DOIUrl":"https://doi.org/10.3389/frspt.2023.1181843","url":null,"abstract":"Biologics, such as pharmaceutical peptides, have notoriously short shelf lives, insufficient for long-duration space flight missions to the Moon or Mars. To enable the sustainable presence of humans on the Moon or Mars, we must develop methods for on-site production of pharmaceutical peptides in space, a concept we call the Astropharmacy. Here, we present a proof-of-concept for the first step needed: a low-mass system for pharmaceutical production designed to be stable in space. To demonstrate feasibility, we engineered strains of the space-hardy spore-forming bacterium, Bacillus subtilis, to secrete two pharmaceutical peptides important for astronaut health: teriparatide (an anabolic agent for combating osteoporosis) and filgrastim (an effective countermeasure for radiation-induced neutropenia). We found that the secretion peptides from the walM and yoqH genes of B. subtilis worked well for secreting teriparatide and filgrastim, respectively. In consideration of the Translational Research Institute for Space Health (TRISH) challenge to produce a dose equivalent in 24 h, dried spores of our engineered strains were used to produce 1 dose equivalent of teriparatide from a 2 mL culture and 1 dose equivalent of filgrastim from 52 mL of culture in 24 h. Further optimization of strain growth conditions, expression conditions, and promoter sequences should allow for higher production rates to be achieved. These strains provide the template for future optimization efforts and address the first step in the Astropharmacy, capable of on-site production, purification, and processing of biopharmaceutical compounds in platforms amenable for use in space.","PeriodicalId":137674,"journal":{"name":"Frontiers in Space Technologies","volume":"329 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139203102","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A comparative analysis of reinforcement learning algorithms for earth-observing satellite scheduling","authors":"Adam Herrmann, Hanspeter Schaub","doi":"10.3389/frspt.2023.1263489","DOIUrl":"https://doi.org/10.3389/frspt.2023.1263489","url":null,"abstract":"Deep reinforcement learning (DRL) has shown promise for spacecraft planning and scheduling due to the lack of constraints on model representation, the ability of trained policies to achieve optimal performance with respect to a reward function, and fast execution times of the policies after training. Past work investigates various problem formulations, algorithms, and safety methodologies, but a comprehensive comparison between different DRL methods and problem formulations has not been performed for spacecraft scheduling problems. This work formulates two Earth-observing satellite (EOS) scheduling problems with resource constraints regarding power, reaction wheel speeds, and on-board data storage. The environments provide both simple and complex scheduling challenges for benchmarking DRL performance. Policy gradient and value-based reinforcement learning algorithms are trained for each environment and are compared on the basis of performance, performance variance between different seeds, and wall clock time. Advantage actor-critic (A2C), deep Q-networks (DQN), proximal policy optimization (PPO), shielded proximal policy optimization (SPPO) and a Monte Carlo tree search based training-pipeline (MCTS-Train) are applied to each EOS scheduling problem. Hyperparameter tuning is performed for each method, and the best performing hyperparameters are selected for comparison. Each DRL algorithm is also compared to a genetic algorithm, which provides a point of comparison outside the field of DRL. PPO and SPPO are shown to be the most stable algorithms, converging quickly to high-performing policies between different experiments. A2C and DQN are typically able to produce high-performing policies, but with relatively high variance across the selected hyperparameters. MCTS-Train is capable of producing high-performing policies for most problems, but struggles when long planning horizons are utilized. The results of this work provide a basis for selecting reinforcement learning algorithms for spacecraft planning and scheduling problems. The algorithms and environments used in this work are provided in a Python package called bsk_rl to facilitate future research in this area.","PeriodicalId":137674,"journal":{"name":"Frontiers in Space Technologies","volume":"185 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139213490","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Kessler’s syndrome: a challenge to humanity","authors":"Amrith Mariappan, J. Crassidis","doi":"10.3389/frspt.2023.1309940","DOIUrl":"https://doi.org/10.3389/frspt.2023.1309940","url":null,"abstract":"Kessler’s Syndrome is a global phenomenon characterized by the presence of tens of millions of debris pieces of various sizes that disrupt satellite operations. This article delves into the potential outcomes of a Kessler’s Syndrome occurrence and its implications on satellite operations. The potential threats posed by this scenario are discussed, including the implications of minimal to no satellite function on human impacts, including crashes and minimized or disrupted functions in essential utility services, as these sectors heavily rely on satellites. In addition, we discuss how the loss of satellite communications could gradually or rapidly affect global affairs. As humans are a dominant force on Earth, their endangerment would reverberate throughout the ecological system, potentially leading to the demise of other species. It is crucial for policymakers and relevant stakeholders to recognize these implications and work towards safeguarding satellite communication to mitigate potential negative outcomes for humanity’s wellbeing and progress. The recycling of space debris emerges as a promising and long-term sustainable solution to the mitigation of space debris. By repurposing decommissioned satellites and debris into useful materials to support other space missions, this recycling strategy presents a win-win scenario, promoting environmental sustainability and resource efficiency in space exploration.","PeriodicalId":137674,"journal":{"name":"Frontiers in Space Technologies","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139224637","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modeling the influence of an electric thruster’s ion beam on its global EMC","authors":"Y. Rover, R. Thueringer, Uwe Probst, Chris Volkmar","doi":"10.3389/frspt.2023.1287474","DOIUrl":"https://doi.org/10.3389/frspt.2023.1287474","url":null,"abstract":"This research deals with electromagnetic compatibility (EMC) in the field of electric propulsion (EP). To complete previous investigations, the emissions of a fully operating radio-frequency thruster (RIT)—including its extracted ion beam—were numerically analyzed. The ion beam was simulated and investigated with various characteristics. The simulations were performed by means of transient co-simulation. It is clear that the ion beam had a significant impact on the thruster emissions. Properties such as divergence angle and the conductivity of the beam, which can be directly attributed to the operating point of the plasma discharge inside the thruster, play a major role. The next steps will be to bring together all the knowledge gained about the emissions of the individual thruster components as well as the peripheral electronics.","PeriodicalId":137674,"journal":{"name":"Frontiers in Space Technologies","volume":"3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139232137","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Radiation characteristics of an aerogel-supported fission fragment rocket engine for crewed interplanetary missions","authors":"Ryan Weed, R. V. Duncan, Matthew Horsley, George Chapline","doi":"10.3389/frspt.2023.1197347","DOIUrl":"https://doi.org/10.3389/frspt.2023.1197347","url":null,"abstract":"The ionizing radiation properties of a fission fragment rocket engine concept are described in the context of a crewed Mars mission. This propulsion system could achieve very high specific impulses (>106 s) at a high power density (>kW/kg), utilizing micron-sized fissile fuel particles suspended in an aerogel matrix. The fission core is located within the bore of an electromagnet and external neutron moderator material. The low-density aerogel allows for radiative cooling of fuel particles while minimizing collisional losses with the fission fragments, leading to a more efficient use of fissile fuel in producing thrust compared to previous concepts. This paper presents the estimates of the steady-state ionizing radiation equivalent dose to the astronaut crew from both external (e.g., galactic cosmic rays) and internal (reactor) sources. The spacecraft design includes a centrifugation concept where the transit habitation module rotates around the spacecraft’s center of mass, providing artificial gravity to the crew and the separation distance to the nuclear core. We find that the fission fragment propulsion system combined with centrifugation could lead to reduced transit time, reduced equivalent radiation doses, and a reduced risk of long-term exposure to micro-g environments. Such a high-specific impulse propulsion system would enable other crewed fast transit, high delta-V interplanetary missions with payload mass fractions much greater than those of alternative propulsion architecture (chemical and solar electric).","PeriodicalId":137674,"journal":{"name":"Frontiers in Space Technologies","volume":"195 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124336988","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Blood-brain-barrier modeling with tissue chips for research applications in space and on Earth","authors":"Anne Yau, Aditi H. Jogdand, Yupeng Chen","doi":"10.3389/frspt.2023.1176943","DOIUrl":"https://doi.org/10.3389/frspt.2023.1176943","url":null,"abstract":"Tissue chip technology has revolutionized biomedical applications and the medical science field for the past few decades. Currently, tissue chips are one of the most powerful research tools aiding in in vitro work to accurately predict the outcome of studies when compared to monolayer two-dimensional (2D) cell cultures. While 2D cell cultures held prominence for a long time, their lack of biomimicry has resulted in a transition to 3D cell cultures, including tissue chips technology, to overcome the discrepancies often seen in in vitro studies. Due to their wide range of applications, different organ systems have been studied over the years, one of which is the blood brain barrier (BBB) which is discussed in this review. The BBB is an incredible protective unit of the body, keeping out pathogens from entering the brain through vasculature. However, there are some microbes and certain diseases that disrupt the function of this barrier which can lead to detrimental outcomes. Over the past few years, various designs of the BBB have been proposed and modeled to study drug delivery and disease modeling on Earth. More recently, researchers have started to utilize tissue chips in space to study the effects of microgravity on human health. BBB tissue chips in space can be a tool to understand function mechanisms and therapeutics. This review addresses the limitations of monolayer cell culture which could be overcome with utilizing tissue chips technology. Current BBB models on Earth and how they are fabricated as well as what influences the BBB cell culture in tissue chips are discussed. Then, this article reviews how application of these technologies together with incorporating biosensors in space would be beneficial to help in predicting a more accurate physiological response in specific tissue or organ chips. Finally, the current platforms used in space and some solutions to overcome some shortcomings for future BBB tissue chip research are also discussed.","PeriodicalId":137674,"journal":{"name":"Frontiers in Space Technologies","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121415050","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}