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• First quantitative prediction of elements from space debris in 2016–2050. • The predicted elements are Al, Al 2 O 3 , Ti, Fe, Cu and Ag. • The masses of resource elements at 400 km altitude will increase towards 2050. • Al and Ti at 400 km altitude band will increase at least 10 times from 2016 to 2050. • Our model simulation suggests a space resource potential of space debris. The proliferation of space debris poses a significant challenge in modern space exploration, with potential repercussions for the future space environment and activities. Various research and technological developments have addressed these concerns, including estimating the number of space debris orbiting the Earth and its efficient removal. This paper proposes a novel resource-oriented perspective on space debris and focuses on the composition and resource potential of space debris. This study forecasts for the first time the annual mass changes in resource materials (Al, Al 2 O 3 , Ti, Fe, Cu, and Ag) by the year 2050 by employing a debris environment model simulation. Our simulation reveals that the masses of all the studied resource elements in an Earth orbital altitude of 400 km will increase by 2050. For example, Al and Ti at the 400 km altitude band will increase from 3.0 × 106 kg and 3.2 × 105 kg (in 2016) to 3.8 × 107 kg and 4.2 × 106 kg (in 2050), respectively, climbing at least ten times from 2016 to 2050, on the conservative estimates with a high post-mission disposal success rate. These comparative influxes of Al and Ti in 2050 due to space debris are at least 100 times higher than the natural influxes into the Earth's atmosphere due to meteoroids, further highlighting the significance of space debris. Our simulation results suggest that space debris may hold significant space resource potential in the next 25 years but can be a considerable environmental contaminant impeding space sustainability. [ABSTRACT FROM AUTHOR]

• Investigating the issue of computation of multi-revolution NRHO under the ephemeris model. • Analyzing the failure of computation by means of the condition number of STM (State Transition Matrices). • Proposing the strategy of segment selection to improve the convergence of computation. • Computing the lunar L1/L2 NRHOs up to 500 revolutions, the maximal number in the current publications. • No dedicated optimization algorithm or commercial software required for the proposed method. Near Rectilinear Halo Orbits (NRHOs) are vital to manned lunar and deep space exploration, which nowadays are of great interest for different space agencies and in particular with regard to the future space station. However, the required computation of multi-revolution NRHO under the ephemeris model is difficult, especially for the NRHOs with low periapsis relative to the secondary body. This paper explores this issue from the perspective of multiple shooting, first analyzing the influence of the state transition matrices by means of their condition number and then, focusing on a good selection of trajectory segments with suitable patch points. The methodology considerably improves the convergence and the computation under the ephemeris model. Numerical simulations show that at least 30 revolutions can be achieved for NRHOs with perilune radius of less than 12,000 km around L1 or period less than 8.8 days around L2; meanwhile, the number of segments used can be as low as 2 for each single revolution. As for the position of patch points, the first and last points of each revolution should be apart from the Moon, and the distance can be reduced only when the number of segments increases. The proposed method requires no dedicated optimization algorithm or commercial software to produce the multi-revolution NRHOs. [ABSTRACT FROM AUTHOR]

Electrospray technology has been widely applied in many fields, including materials science, chemical engineering, pharmaceuticals, and aerospace exploration. In particular, with the development of commercial space exploration and the demand for miniaturization of micro-nano satellites, capillary electrospray thrusters using ionic liquids as propellants have received extensive attention. However, the use of a single capillary emitter limits the overall performance of the thruster. To further enhance the emission performance of the thruster, the coaxial capillaries emitter with hybrid ionic liquids has been proposed. In this paper, the experimental observation was conducted on the situation where the same ionic liquid was injected into the inner and outer capillaries at different flow rates. It was observed that the outer cone-jet gradually envelops the inner cone-jet to evolute a coaxial cone-jet. Single ionic liquid coaxial electrospray has a limited effect on the stability of the cone-jet. Therefore, 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIM-BF 4) and 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF 6) were separately supplied into the inner and outer capillaries to form a coaxial cone-jet. The results revealed a significant improvement in the current noise spectrum, and it was capable of stable emission current even at higher flow rates. Further analysis of the plume composition was conducted using the time-of-flight method. The results indicated that EMIM-BF 4 and BMIM-PF 6 supplied in outer and inner capillaries respectively as coaxial electrospray can provide the best specific impulse and thrust performances for the electrospray thruster in the conducted experiments. This greatly improves the thrust provided by a single emitter position of the thruster, which expands its application prospects. The coaxial electrospray current with different ionic liquid flow rates is studied. Optimized the cone-jet and current stability by coaxial capillary emitters. The most effective combination of ionic liquids in coaxial emitters is researched. Compared and analyzed specific impulses and thrusts for different emitter forms. [ABSTRACT FROM AUTHOR]

In recent years, prominent spacefaring nations have redirected their attention towards the Moon as a potential avenue for economic prospects and as a pivotal waypoint for extended space exploration endeavors. Nonetheless, a notable concern has emerged regarding the dispersion of lunar dust during lunar landings, a phenomenon that has been associated with documented instances of equipment damage during prior missions. To mitigate these challenges, leading research institutions are actively engaged in endeavors aimed at minimizing the adverse effects of dust dispersal during lunar and extraterrestrial landings. This review paper provides a comprehensive overview of ongoing research and development endeavors focusing on the interaction dynamics between rocket plumes and lunar surfaces, along with the resultant dispersion of lunar dust triggered by rocket plume impingement. Additionally, it presents research efforts aimed at developing lunar dust mitigation technologies. • This paper conducts a survey of research on rocket plumes and lunar dust dispersal. • The challenges posed by lunar dust during past lunar landings are explored. • The effects of lunar dust dispersal through in-situ experiments are investigated. • Previous and ongoing experiments and numerical methods are examined. • Continued research in plume-surface interactions to mitigate hazards is crucial. [ABSTRACT FROM AUTHOR]

Nano-satellites are essential tools for various applications, including scientific experiments, deep space exploration and astronomical observation. Achieving precise model predictions is crucial for their successful operation. To address the intricate constraints of nano-satellites and enhance control performance, the Model Predictive Control (MPC) algorithm is an effective solution. However, implementing an MPC-based attitude control system in actual engineering scenarios presents significant challenges, primarily due to the substantial computational burden, especially given the limited onboard computing resources of nano-satellites. In this paper, we introduce a modified adaptive self-triggered model predictive control (ST-MPC) algorithm designed to stabilize the attitude of nano-satellites, while simultaneously reducing communication and computational overhead compared to traditional MPC methods. The proposed self-triggered mechanism dynamically determines the next trigger time according to the system state. Moreover, we incorporate considerations for the efficiency of actuators to address the constraints imposed by the magnetic torque characteristics within the modified self-triggered mechanism. Additionally, a strategy for adaptive prediction horizon is proposed to balance computation load and control accuracy. The results of our simulations demonstrate the effectiveness of the modified ST-MPC algorithm in comparison to both traditional MPC and standard ST-MPC approaches. This algorithm may have the potential to significantly impact attitude control applications for nano-satellites. [ABSTRACT FROM AUTHOR]

The International Space Station currently requires four annual replenishments for food supply, a practice that won't be feasible for deep space missions due to the greater distances. Based on the design of closed ecological life support systems, two waste streams were identified: urea from the crew urine, volatile fatty acids (VFAs) from a first stage of anaerobic digestion of waste. The objective of this study was to assess the ability of bacterium Cupriavidus necator to produce single cell protein on urea and VFAs. Thus, the effect of carbon sources (glucose vs VFAs) and the dilution rate on the biomass composition was determined in continuous cultures. Complete transformation of the carbon source into protein-rich biomass was achieved up to 78 % cell dry weight (CDW). For both carbon sources, the protein content increased from 55.0 %CDW to 78 %CDW with a decrease in the dilution rate. Conversely, the nucleic acid and polyhydroxyalkanoate contents decreased with the dilution rate from 8.8 %CDW to 4.8 %CDW and 9.8 %CDW to 0.6 %CDW respectively. Working at a low dilution rate seems to be a good way to maximize protein content while minimizing unwanted nucleic acids and polyhydroxyalkanoates. [Display omitted] • C. necator continuous cultivations led to total consumption of the carbon sources. • Biomass composition changes with dilution rate regardless carbon source. • Bioplastics were produced even under carbon limitation. [ABSTRACT FROM AUTHOR]

With crewed deep space exploration on the horizon, preparation for potential astronaut health crises in space missions has become vital. Administration of anaesthesia and analgesia presents many challenges owing to constraints specific to space (physiologic and ergonomic challenges associated with microgravity) and nonspecific factors (isolation and lack of supplies). Regional anaesthesia can be the safest option; however, we hypothesised that the ergonomics of microgravity would compromise ease and accuracy of nerve blocks. We evaluated the feasibility of regional anaesthesia in a simulated microgravity environment (free-floating underwater conditions) using a meat (bovine muscle) model. Forty meat models were randomised for injection under simulated microgravity or normal gravity conditions. Success rates were determined by blinded assessors after injection. Parameters assessed included time to block, ease of image acquisition, and ease of needle placement. The median time to block in normal gravity was 27 (interquartile range 21–69) s vs 35 (interquartile range 22–48) s in simulated microgravity (P =0.751). Ease of image acquisition was similar in both conditions, as was ease of needle placement. There was no significant difference in the rate of accidental intraneural injections (5% vs 5%), with block success rates comparable in both scenarios (80% normal gravity vs 85% microgravity, P >0.999). Regional anaesthesia appears feasible for experts in simulated microgravity despite the ergonomic challenges. Although our model has limitations and might not fully capture the complexities of actual space conditions, it provides a foundation for future research into anaesthesia and analgesia during deep space missions. [ABSTRACT FROM AUTHOR]

The planetary construction is necessary for long-term scientific deep space exploration and resource utilization in the future. The planetary robotic assembly control is a key technology that must be broken through in future planetary surface construction. The paper focuses on the most representative dual peg-in–hole assembly, which has sufficiently complex contact interaction, wide range of applications and good method portability. To address the challenges brought by the unstructured planetary environment and the features of the construction tasks, the paper proposes an end-to-end deep reinforcement learning and control method with multimodal perception for planetary robotic assembly tasks. A staged reward function based on the visual virtual target point for policy learning is designed. The effectiveness and feasibility of the proposed control method have been verified through simulation experiments and ground real robot experiments. It provides a feasible control method of robotic operations for future planetary surface construction. [ABSTRACT FROM AUTHOR]

The Sun exhibited lower-than-average activity levels, including a weak maximum and a prolonged minimum in the solar cycle (SC) 24. Thiswas following a 60-year trend of weakening solar activity, leading to speculations that we could be moving into another secular minimum scenario like the Dalton or the Gleissberg periods. During such periods, the fluxes of galactic cosmic rays (GCRs) increase significantly, introducing radiation hazards for long-term crewed space explorations. In our previous work, we predicted the level of solar activity, and thus, the radiation environment for SC25 will be similar to SC24. In this paper, we show that, to date, the radiation environment observed by CRaTER has been similar to SC24, as we predicted. Furthermore, we predict that if the radiation environment remains similar to SC24, the maximum value for permissible mission duration (PMD) for SC25 will be 917 - 230 + 234 days based on NASA's latest permissible exposure limit (PEL). [ABSTRACT FROM AUTHOR]

Space Traffic Management (STM) is becoming increasingly important as new space activities emerge, such as mega-constellations, on-orbit servicing etc. These developments, although promising great advances, nevertheless present complicated issues that demand stringent technical constraints. Effective STM necessitates extensive rules to ensure the safety, sustainability, and orderly execution of space operations. This research emphasizes the critical need for updated technical regulations that address the operational complexities involved with these new activities. It seeks to build a secure and collaborative space environment by establishing detailed legislative frameworks and emphasizing international cooperation, so ensuring the long-term profitability and success of space exploration and usage. Through meticulous analysis, the paper identifies regulatory gaps and proposes a robust framework capable of accommodating the evolving landscape of regulations. Drawing upon humanity's collective experience across different domains, the proposed framework aims to foster responsible growth in outer space while safeguarding its integrity for future generations. This paper examines the existing regulatory framework applicable to four distinct categories of New Technologies and Activities in space; identifies gaps where they exist; and suggests a capable and robust regulatory framework. This framework leverages humankind's experience in other domains to nurture and assist responsible growth in the outer space domain while ensuring proper stewardship of that domain, now and in the future. This paper is based on the report prepared by members of working group 4.2 of the Space Traffic Management Committee (TC 26). • Examined regulations across national, supranational, and international levels, distinguishing between Hard Law and Soft Law. • Supported ISO Standard 24330 for space systems on rendezvous, proximity operations, and on-orbit servicing, with updates. • Promoted development of Alternative Dispute Resolution guidelines for Space Environment Management and related technologies. • Encouraged dialog among IGOs, NGOs, commercial entities, and stakeholders on Space Operations and Management, and Traffic Management. • Advocated global commercial standards via industry associations and proposed a UN-level International Spacefaring Organization. [ABSTRACT FROM AUTHOR]

The problem of space debris removal from the near-Earth space is being studied in almost every country taking part in space exploration. This is due to the global threat of critical increase in the number of space debris objects predicted for the near future, in particular as a result of significant growth in demand for multi-satellite constellations for various purposes. To date, researchers have proposed a large number of different methods for space debris removal. The work presented is the development of one of the promising contactless methods of space debris removal by an ion beam. The results of modeling and optimization of physical processes in the ion source to be mounted on board a service spacecraft that is necessary for implementing the considered method of space debris removal are presented. Besides, the results of thermal modeling and thermal mapping of the ion source during its operation are presented also, and the calculation results of its output parameters are compared to experimental data, which verified the small divergence angles of the generated ion beam. To assess the prospects of using a system for contactless space debris transportation by an ion beam using the obtained data on the operating parameters of the ion source, the trajectory design and mission analysis were carried out, which revealed the feasibility of removing seven space debris objects out of the protected region in geostationary orbit by a single service spacecraft. Besides, the preliminary service spacecraft design is presented. • Active space debris removal system development. • Ion source as a basic element of the system for contactless space debris removal designing and testing. • The service spacecraft preliminary design, its mass budget and power consumption are presented. [ABSTRACT FROM AUTHOR]

As humanity continues its space exploration, understanding biological evolution in extraterrestrial environments will become crucial. On Earth, organisms have adapted to new environments, and some genetic data indicate positive natural selection. This paper investigates the impact of space environments, such as high radiation and microgravity, which may lead to high mutation rates and positive selection, on biological evolution, using numerical analysis. It quantifies the evolutionary rates and the time until a new mutation reaches fixation (100 % frequency within population) beyond Earth. The findings reveal accelerated evolution rates, 1,000 to 10,000 times faster than on Earth for beneficial mutations, with the time until fixation being 0.002 to 0.004 times shorter, assuming mutation rates are 10–100 times higher. These results offer insights into various areas, including space facility design, space agriculture, astrobiological exploration, and life sustainability beyond Earth and Solar System, illuminating the potential for a 'Big Bang of Evolution' in outer space. • High radiation and microgravity in space accelerate evolutionary rates. • Beneficial mutations evolve 1,000–10,000 times faster in space than on Earth. • Mutation fixation time in space is 0.002–0.004 times shorter than on Earth. • Findings impact space habitats, agriculture, and biodiversity in space. • Organisms may adapt rapidly in space, leading to a "Big Bang of Evolution." [ABSTRACT FROM AUTHOR]

We discuss the relatively overlooked problem of All Clear in Solar Energetic Particle (SEP) event prediction. These proton and heavier ion events are injected in major solar eruptions, propagate directionally into the heliosphere at relativistic speeds and threaten equipment and personnel at low-Earth orbit and beyond. SEPs are rare to extreme events associated with solar flares and coronal mass ejections (CMEs), with one SEP event detected in-situ every several hundreds of flares and CMEs observed remotely. This abysmal overall association improves drastically to below 1:2 for fast (i.e., shock-fronted) and halo (i.e., propagating mainly along the Sun–Earth line) CMEs. All Clear implies an assessment of tolerable conditions within a preset prediction window. Relying on one of the most comprehensive data sets for SEP events, we implement a methodology that provides an All Clear for events of NOAA severity S1 and above (S1+) and identify the minimal eruption attributes (flare size and CME speed) that could give rise to such SEP events from source locations in the Sun. The results correspond to and reflect settings of minimum complexity, giving rise to different attributes for different longitudinal zones in the earthward solar hemisphere. This work presents proof of concept; complexity can be increased at will for more demanding All Clear definitions, subject only to sufficient statistics due to the scarcity of the phenomenon. At this point, feedback is desired from stakeholders on what fits their definition of All Clear (we expect different definitions from different operators), so that to define the precise settings on which to run this and similar exercises. • The overlooked All Clear problem for Solar Energetic Particle events revisited. • All Clear is as important as event prediction in new era of human space exploration. • All Clear definitions vary by stakeholder: cross-communication is necessary. • Self-consistent, generic and flexible methodology for actionable decision-making. • All Clear and event prediction invariably on eruptive potential of solar sources. [ABSTRACT FROM AUTHOR]

Practical space exploration has a priority the issues of safety of space missions. And an important fundamental problem arises — the study of the evolution and the stability of a space debris cloud, consisting of artificial objects remnants, or debris of extra-terrestrial origin. We discuss a new behavior of mechanical system near an unstable equilibrium position — the trajectories located in the selected neighborhood of unstable equilibrium. As an important application, we consider perturbed motion in collinear libration points vicinity of the restricted circular three-body problem. Numerical simulations for the parameters of the Earth–Moon system convincingly illustrate our theoretical study. This mathematical model allows us predicting how long the debris with certain energy can fly in vicinity of unstable collinear libration point, being close to the localized trajectory. This must be taken under consideration when planning the space missions. And also the localized trajectories may be useful when spaceship flies around the collinear libration point. • New behavior of mechanical system near an unstable equilibrium position is considered. • Existence of numerous trajectories in small neighborhood of unstable equilibrium is proven. • Perturbed motion in vicinity of collinear libration points of the Earth–Moon system is presented. • Long fly closed to the localized trajectory of the debris with certain energy is studied. [ABSTRACT FROM AUTHOR]

Deep space exploration embodies the human aspiration to comprehend the universe, with the sampling of extraterrestrial celestial bodies (ECBs) serving as a critical precursor for the development of space-based resources. The process of drilling deep into regolith layers is pivotal in ECBs sampling endeavors. To more directly scrutinize the drilling and sampling procedures, discrete element method (DEM) simulations are extensively employed to assess the stress on drilling apparatus and to model drilling and sampling challenges. However, numerous researchers have only conducted localized simulation analyses for specific interest issues. This paper supplements research in this field by constructing a comprehensive DEM model of the entire drilling sampling procedure. By integrating the Hertz-Mindlin with bonding contact model and leveraging dynamic analysis outcomes, the actual drilling scenario was replicated to the greatest extent feasible while minimizing computational demands. Consequently, this model can be utilized to simulate and evaluate both the drilling tool's impact and the sampling conditions. By juxtaposing simulation results with field test empirical data, the model's accuracy is confirmed. Factors influencing the sampling quantity are observed and analyzed, leading to recommendations for optimizing the drilling system. Finally, some conclusion remarks are made. • Drilling process in extraterrestrial celestial bodies regolith can be simulated by discrete element simulation. • Simulation of the drilling process reveals a number of phenomena that affect the sampling results. • Simplified model to reflect actual drilling conditions. • Simulation results are instructive for parameter optimization. [ABSTRACT FROM AUTHOR]

The space sector is evolving from the "Legacy Space" to the "New Space". Along with the space sector, space program governance is transitioning to support an environment where legacy and New Space actors co-exist. The aforementioned transitions and the entry of New Space players result in new governance models, as space agencies aim to exploit contributions from non-space sectors, leveraging on collaborative opportunities. Public-private partnerships (PPPs) become a new golden rule, disclosing unprecedented achievements. However, the existing body of knowledge lacks a framing of models of space program governance, covering both Legacy Space programs and New Space ones. It is not clear how the roles and responsibilities of stakeholders change from the Legacy Space to the New Space, alongside the related changes in contract structures and the practices space agencies favour in current space programs and projects. Therefore, our paper aims to investigate how space program governance evolved. We performed a single-case study on NASA-led space exploration programs to investigate the transition of space program governance and its actual state-of-the-art. We co-developed and validated three governance models for space programs through semi-structured interviews with senior experts. Furthermore, we present key drivers and barriers behind the evolution towards New Space governance models. We found and discussed three program governance models corresponding to the evolutionary stages of space exploration programs. In the Legacy Space model, the government owns space infrastructures to demonstrate technological supremacy. In the Transitional model, lumpsum contracts, transitioning between cost-plus and fixed-price, replace the legacy EPC (Engineering, Production, Construction) ones. In the New Space model, collaborative efforts and PPPs enable alignment between public and private expertise. Finally, we examine the factors that promote and impede the evolution of space governance, leading to the emergence of a polycentric governance structure observed in current space programs. The three models enable managers to visualize space programs from a governance perspective, where stakeholders' roles and responsibilities in PPPs are clearly identified. Moreover, managers can leverage and innovate existing practices for transitioning across different models of governance in space programs and projects. We contribute to research by introducing a transitional governance model that enables the smooth transition between the Legacy Space and the New Space paradigms. We justify the concurrent adoption of multiple governance models within the same space program, as in the current Artemis program. • Diverse space program governance models can be found in the Apollo, ISS, and Artemis programs. • The New Space ecosystem is characterized by collaborative efforts between the public and private sectors. • Cooperation and partnerships in space activities enable the sharing of risks, costs, and resources. • Adoption of innovative program management practices is supported by cost-effectiveness but limited by organizational culture. • According to polycentric governance structures, some projects follow legacy practices, and some follow a New Space approach. [ABSTRACT FROM AUTHOR]

In recent years, the proliferation of IoT technologies and the widespread adoption of wireless sensors across various critical infrastructures such as power plants, service monitoring systems, space and earth exploration missions, and water treatment facilities have resulted in the generation of vast quantities of multivariate time series data. Within this context, unsupervised anomaly detection has emerged as a pivotal yet challenging problem in time series research, necessitating machine learning models capable of identifying rare anomalies amidst massive datasets. Traditionally, unsupervised methods have approached this issue by learning representations of primary patterns within sequences and detecting deviations through reconstruction errors. However, the effectiveness of this approach is often limited due to the intricate dynamics and diverse patterns inherent in these dynamic systems. Moreover, many existing unsupervised anomaly detection techniques fail to fully exploit inter-feature relationships within multivariate time series data, thereby overlooking a crucial criterion for accurate detection. To address these shortcomings, this paper introduces a novel unsupervised method for multivariate time series anomaly detection based on normalized flows and autoencoders. Central to our approach is the incorporation of a channel shuffling mechanism during training, enhancing the model's capacity to discern inter-channel patterns and anomalies. Concurrently, the application of normalized flows within the autoencoder framework serves to constrain the latent space, effectively isolating anomalies and improving detection accuracy. Experimental validation conducted on two large-scale public datasets demonstrates the efficacy of the proposed method compared to established benchmarks, highlighting its superior performance. [ABSTRACT FROM AUTHOR]

Spacecraft formation flying for interferometric observations around the 2nd Lagrange point in the Sun-Earth system (SEL2) is currently focal point in deep space exploration research, which demands high precision in relative position control of spacecraft. This paper proposes the relative motion dynamics of satellite formations around the L2 point in the port-Hamiltonian framework, and establishes a high-precision nonlinear dynamics model. PID passivity-based control (PID-PBC) is widely used in engineering. However, existing methods of PID-PBC cannot address the trajectory tracking issues in port-Hamiltonian systems. Utilizing the contraction properties of the port-Hamiltonian system, this paper proposes the trajectory tracking PID-PBC (tPID-PBC) approach, effectively resolving trajectory tracking issues for formation dynamics around L2 point in port-Hamiltonian framework. The paper details explicit solutions of the Partial Differential Equations (PDE) for the tPID-PBC method and its controller structure, and references the trajectories of interferometric observation formations, to verify the method's effectiveness through numerical simulation. The presented control approach is applicable across generic port-Hamiltonian systems, offering substantial theoretical value. [ABSTRACT FROM AUTHOR]

• Stability of prior coordination solutions influences learning of new solutions. • A more stable prior solution makes it harder to learn a new solution. • Using less stable solutions increases null space exploration. • Participants return to stable solutions even after learning less stable ones. Motor learning does not occur on a 'blank slate', but in the context of prior coordination solutions. The role of prior coordination solutions is likely critical in redundant tasks where there are multiple solutions to achieve the task goal – yet their influence on subsequent learning is currently not well understood. Here we addressed this issue by having human participants learn a redundant virtual shuffleboard task, where they held a bimanual manipulandum and made a discrete throwing motion to slide a virtual puck towards a target. The task was redundant because the distance traveled by the puck was determined by the sum of the left- and right-hand speeds at the time of release. On the first day, 37 participants in different groups practiced symmetric or asymmetric solutions. On the second day, all participants transferred to a common criterion task, which required an asymmetric solution. Results showed that: (i) the symmetry of the practiced solution affected motor variability during practice, with more asymmetric solutions showing higher exploration of the null space, (ii) when transferring to the common criterion task, participants in the symmetric group showed much higher null space exploration, and (iii) when no constraints were placed on the solution, participants tended to return to the symmetric solution regardless of the solution originally practiced. Overall, these results suggest that the stability of prior coordination solutions plays an important role in shaping learning in redundant motor tasks. [ABSTRACT FROM AUTHOR]

Silicon carbide (SiC) ceramic lattice structures (CLSs) hold significant potential for use in structural components and optical mirrors in space exploration due to their light weight, high strength, and excellent dimensional stability. However, they face challenges such as poor curing performance and weak mechanical strength during the digital light processing (DLP) additive manufacturing process. In this study, SiC@Al 2 O 3 powder was prepared, resulting in a 21 % reduction in absorptivity compared to bare SiC powder. The ceramic paste derived from this powder achieved a curing thickness of up to 80 μm, exhibited a reduced over-curing width, and demonstrated a 75 % improvement in stability compared to bare SiC paste. Consequently, high-quality triply periodic minimal surfaces (TMPS) structured SiC@Al 2 O 3 CLSs green bodies were successfully fabricated. By integrating precursor impregnation pyrolysis with the reaction melting infiltration (PIP-RMI) post-treatment densification method, SiC@Al 2 O 3 /Si CLSs were produced, exhibiting superior mechanical properties with low dimensional shrinkage. At 30 % volume fraction, the specific compressive strength of the primitive-TPMS SiC@Al 2 O 3 /Si CLSs reached 24.79 MPa. This study presents an effective method for fabricating SiC-based CLSs and establishes a foundation for the optimization of SiC ceramic fabrication processes. [ABSTRACT FROM AUTHOR]

Traditionally, NASA mission planners have used a heuristic and qualitative approach to design medical systems based on prior experience; however, this approach may result in implicit bias in design. The risk of needing to return to definitive care (RTDC) or medevac, has been particularly difficult to quantify due to the complexity of exploration spaceflight. The Informing Mission Planning through Analysis of Complex Tradespaces (IMPACT) tool is a probabilistic risk assessment approach designed by NASA to model medical risk in long duration spaceflight. This paper discusses how this tool can inform RTDC risk and improve the health and safety of astronaut crews. IMPACT was developed by subject matter experts using an evidence-based approach and can be used to quantify the risk of exceeding the onboard medical capabilities. Within the model, RTDC occurs when a condition meets a specific threshold that exceeds the on-board capabilities and requires a higher level of care. A notional lunar surface design reference mission (DRM) was modeled using IMPACT, and the RTDC rate was analyzed. Of the 119 medical conditions evaluated, thirty-four were preassigned to have zero probability of RTDC based on lack of acuity. Thirty-one conditions used the need for inpatient hospitalization or admission to intensive care as the RTDC surrogate. Twenty-six conditions used the probability of needing surgery, and ten conditions used treatment failure rates as the RTDC surrogate. The remaining 18 conditions had unique surrogates that did not fall into the above categories or were assigned a 100 % probability of RTDC due to their definition. In the sample DRM, the overall risk for RTDC was 0.32 events per mission. Quantifying medical risk for human spaceflight is challenging but important in designing medical systems that support the health and performance of our astronaut crews. IMPACT can use the best available evidence to quantify the risk of an RTDC event based on mission parameters and help mission planners make informed design decisions. More work is underway to further refine the model and evidence that drives the RTDC calculation to improve model fidelity and utility for missions to the Moon, Mars, and beyond. • Human spaceflight is beginning to transition from missions in low Earth orbit to the Moon and Mars. • Medical evacuation from the Moon and Mars will be difficult if not impossible. • Quantify the rate of medical evacuation from 119 relevant conditions for spaceflight. • Modeling tools quantify risk and help mission planners design more valuable medical systems. [ABSTRACT FROM AUTHOR]

As part of MIT's work with the Resources Exploration and Science of OUR Cosmic Environment (RESOURCE) project, in collaboration with NASA Ames and the Solar System Exploration Research Virtual Institute, we investigated the scientific and operational utility of a virtual reality (VR) environment for local, small-scale (<5 m) geological analysis in Lunar and planetary surface exploration missions. A user study was conducted where users explored real environments from Svalbard, Norway, represented in both VR and desktop applications, with the environments mirroring three field sites exhibiting geologic features found on both Earth and Mars. The study aimed to achieve four main objectives: 1) to evaluate if VR improves users' sense of scale, 2) to assess if VR facilitates easier identification of patterns and continuous features, 3) to determine if VR provides a more intuitive method for geological contextualization, and 4) to investigate if VR reduces workload during site exploration. The study, approved by MIT's Institutional Review Board, involved three stages: user training, testing without tools, and geological surveying with tools and fact sheets. Metrics included sense of scale improvement, ease of pattern identification, intuitive geological contextualization, and workload reduction, assessed through questionnaires and the NASA Task Load Index (NASA-TLX). Twenty subjects participated, with tasks randomized across VR and desktop applications. Drone-collected photogrammetry, and environmental data (temperature, humidity and pressure) were collected in Svalbard, Norway, from three distinct geological sites near Longyearbyen. Each site included a water-indicating feature and variation in scale from sub-centimeter to multi-meter. Our comparative study revealed that the VR application provided users with a better sense of scale, improved ability to contextualize geological features, and reduced workload compared to the desktop application. However, while the VR environment enhanced geological contextualization, it showed no significant improvement in the identification of high-level features. We discuss influencing factors for these results and implications for future VR development in geological exploration and astronaut training. • Lessons learned in developing virtual environments for planetary surface exploration and astronaut training. • Field expedition to Svalbard, Norway to collect 3D imagery and environmental sensor data of Mars-relevant geology. • Development of a virtual environment for geological surface exploration of a planetary surface. • User study comparing virtual reality to a desktop application for geological exploration and astronaut training. • Demonstration of improved capabilities using virtual reality for space exploration as a geological field training tool. [ABSTRACT FROM AUTHOR]

• Advances in extraterrestrial resource utilization is reviewed from the aspect of in-situ construction. • Three construction-related in-situ resources are comprehensively reviewed. • Five in-situ construction technologies are sorted and elucidated. • Advice is given for deep, comprehensive and systemic utilization of in-situ resources. To establish foundational support for forthcoming deep space exploration and settlement endeavors, the significance of extraterrestrial construction has become paramount. Recent developments underscore a growing acknowledgment of the imperative role played by in situ resource utilization, attributed to its potential for cost efficiency and facilitation of sustainable progress. This paper compiles and categorizes the advancements in this domain, focusing on three distinctive categories of in situ resources: regolith, water–ice, and energy resources. A review of their distribution, acquisition, and utilization procedures is presented. Subsequently, an intricate examination ensues, elucidating the applicability of each resource within the context of extraterrestrial construction, in conjunction with five prevalent technologies and the latest architectural constructs. Drawing insights from the research, the existing limitations are identified, particularly pertaining to the comprehensive, deep processing, and sustainable utilization of resources. Consequently, a proposition is put forth to address these challenges. Prospective investigations are recommended, focusing on the mining of water–ice, the metallurgy and production of regolith and slag, and the integrated construction in the pursuit of extraterrestrial construction and operational endeavors. [ABSTRACT FROM AUTHOR]

In the recently boosted scenario, the eventual settlement in extreme extra-terrestrial environments, notably the Moon and Mars, stands as critical objective driving the forefront of space exploration endeavours: the possibility of realizing a lunar settlement is currently under study by NASA Artemis Program and others active subjects in the aerospace sector (Schrunk et al., 2008) [1]. As mission duration tends to increase, the wellness of crew members emerges as a stronger concern, affecting the habitat features and driving the design towards solutions that still must face environmental constraints. A wide exploration in the aerospace field has been conducted, starting from the experience accumulated in more than 50 years of experimentation and activity on board of the active and decommissioned space stations. In recent years, several pioneering concepts for human living structures on our satellite have been proposed, with an extensive adoption of transparent inflatable or deployable shells. Even if these proposals can lead the way for optimized solution identification, the technical characterization of these shells has not been extensively explored yet, and it represents a mandatory step in the path for achieving the best possible prototype to be built on the Moon surface. Our research aims to assess the viability of employing transparent or translucent inflatable-type envelopes within the harsh conditions of extra-terrestrial environments. The research background has been extensively investigated in order to identify best practices and promising solutions, which have been proposed here. Where no previous tests were conducted, traditional Earth-related engineering tools where utilized. The result of this work is a multilayer membrane to be deployed through internal air pressurization, with the correct size of each of the composing layers calculated by employing multi-physics simulations employing multi-physics simulations and computational. The outcome of this work represents not a definitive design, but an introductive experience with the aim to launch wider investigations to reach higher TRLs. Finally, we aimed to identify the limits of this research that need to be addressed in order to make an inflatable multilayer membrane feasible to be adopted for long permanent human missions on the Moon. • Deployable technology for extraterrestrial habitat envelope. • Innovative translucent envelope to meet lunar environment requirements. • Computational approach for energetic and structural analysis. • Comparative evaluation with state-of-art opaque membrane technology for space structures. [ABSTRACT FROM AUTHOR]

The exploration of small celestial bodies has been a very active field ever since the dawn of space exploration. However, traditional approaches based on monolithic landers allow only the area in the immediate vicinity to the landing spot to be examined. Using mobile systems like rovers allow for better coverage, but at considerable cost and complexity. In this work, we propose an approach based on swarms of small nonmaneuverable agents, equipped with a sensor package, that are launched from a base station and made to land across the entire surface of the asteroid or comet. The methodology is based on multilateration using small range-finding radio frequency sensors aboard the agents; this enables position determination relative to the base station. Through dynamics simulation, we show that this approach is feasible even in highly irregular gravity fields where closed-form solutions for orbital mechanics are not available, such as the case of comet 67P/Churyumov–Gerasimenko. We show a sensitivity analysis of the absolute position error of the agents which originated from range-measurement error. The surface coverage is evaluated against the numerosity of the swarm. Finally, we show that allowing for a subset of agents to follow a long-period orbit around the object enables better localization of the landed agents, thus increasing the overall performance. • We show a methodology for the exploration of small celestial bodies based on a swarm of sensorized agents. • The swarm is aware of the position of its agents via multilateration enabled by RF range-finding. • The methodology is simulated around the comet 67P/Churyumov–Gerasimenko. • Results show that the approach can cover more than 90% of the surface of the comet. [ABSTRACT FROM AUTHOR]

The Mars Sample Return (MSR) campaign is one of the most ambitious and complex planetary science exploration missions ever pursued. With the participation of NASA, ESA, and many industry partners, MSR aims to bring Martian rock and atmosphere samples to Earth with the goal of answering key questions about Mars' geological, climatological and, potentially, biological evolution. To accomplish this ambitious goal, the MSR campaign relies on three distinct flight elements and a ground element. The Earth Return Orbiter mission that would host the Capture, Containment, and Return System (CCRS) is the last flight element of the trio. The mission would capture the orbiting sample in low Mars orbit (launched into orbit by another mission), contain it, and return it to Earth, landing at the Utah Test and Training Range. Since its early architecture, several changes were adopted by CCRS to improve overall payload efficiency and reduce mass. This paper will discuss the CCRS design, how the current CCRS architecture contributes to an improved mission concept, and the next critical steps of the mission toward its launch. • MSR is one of the most ambitious and complex exploration missions ever pursued. • CCRS is the last flight element of MSR bringing the Mars samples to Earth. • Detailed examination of the NASA CCRS payload is presented. • Insight into the operational plans of CCRS that enables a successful sample return. • Contributes to the broader body of knowledge in space exploration. [ABSTRACT FROM AUTHOR]

This study delves into the impact of substituting Nd 2 O 3 for Na 2 O in Barium–Boron-Phosphate glasses, aiming to enhance their mechanical strength, optical characteristics, and radiation shielding efficacy. Glasses with a composition of 50B 2 O 3 + 20P 2 O 5 + 20BaO + (10-x)Na 2 O + xNd 2 O 3 (x = 0, 1, 2, 3, 4 mol%) were synthesized and characterized. The findings indicate that as the Nd/Na ratio increases, the density of the glass also rises within the range of 3.77–4.23 g/cm3. Moreover, the addition of Nd leads to notable alterations in the optical characteristics of the resulting glasses. Specifically, there is a shift observed in the UV absorption edges, coupled with a noticeable increase in absorption at visible wavelengths. Moreover, Nd 2 O 3 addition reduced the Urbach energy (from 0.6018 to 0.2239 eV for Nd0-Nd4) and the optical band gap indicating improved electronic structure and decreased disorder. The mechanical properties studied using the Makishima-Mackenzie model show As the replacement ratio of Nd 2 O 3 increases, there is a noticeable improvement in the glass's mechanical robustness. Importantly, Glasses with high Nd/Na ratio in their composition exhibit enhanced radiation shielding capabilities, evidenced by increased mass attenuation coefficients and effective removal cross-sections for photons and fast neutrons, respectively. These findings suggest that Nd 2 O 3 -doped glasses offer a promising pathway for developing superior radiation shielding materials with tailored properties for diverse applications in nuclear facilities, medical devices, and space exploration equipment. [ABSTRACT FROM AUTHOR]

This research presents an innovative approach designed to enhance the performance of crater-based navigation systems. The core of this approach revolves around proposing a novel method for calculating and incorporating the degree of perturbation observed in matched craters. The foundation of our algorithm lies in the concept of comparing the similarity of projective invariants between image and database craters during the crater matching process. The degree of perturbation in each extracted crater is quantified and normalized using a multivariate Gaussian model. These values are subsequently employed as observation weights within the navigation system. Simulation results confirm the effectiveness of our approach in accurately computing weights that reflect the varying levels of error between craters. Moreover, when integrated into the navigation system, proposed method substantially elevates navigation performance. [ABSTRACT FROM AUTHOR]

Additive Manufacturing marks a transformative advancement in space exploration, where customization and efficient resource use are paramount. Metal additive manufacturing, specifically using the directed energy deposition process with wire feedstock, addresses the limitations of polymer-based Fused Filament Fabrication, which has been the primary focus of space missions until now. Metal additive manufacturing produces stronger metallic components and optimizes material usage, which is essential for prolonged space missions. Moreover, employing lasers as the heat source in additive manufacturing provides high precision, control, and reduced electromagnetic interference, which is crucial for operating in microgravity and electronic-sensitive environments. This review focuses on laser-based metal additive manufacturing in space exploration, highlighting the pivotal role of numerical simulations in case of limited access to experiments in space. These simulations are vital, cost-effective tools for predicting component quality, enhancing reliability, and optimizing manufacturing parameters in space-based additive manufacturing. By addressing the unique challenges of space additive manufacturing, metal additive manufacturing technologies promise to revolutionize space missions, reducing development costs and time while fulfilling stringent requirements. • Surveyed the state-of-the-art laser metal additive manufacturing in space. • Highlighted pivotal role of numerical simulations in study. • Outlined future directions in this emerging field. [ABSTRACT FROM AUTHOR]

The series of celebrated and grand accomplishments and progress of mankind in space exploration make people more intelligent, quixotic, imaginative, creative and realistic. Also, these imply vision for the future, further exploration and taking advantage of the Universe, for human benefits and sustainability, gaining scientific knowledge and developing engineering structures to that end. The most modern Earth and Universe observation spacecraft to date are now equipped with large lightweight and flexible structures, such as antennas, telescopes, and extendable elements, including the incorporation of more complex and larger appendages with high precision for scientific applications. These demand more stringent structural integrity requirements to minimize performance degradation due to structural damages. In addition, spacecraft structures weight and their associated manufacturing costs should be minimized, most appropriate materials should be utilized, assembly costs should be reduced and fewer parts should be opted, or one-piece more complex configuration parts should be produced. Various sensors, actuators and control technology could be employed to reduce structural damage. Associated with these, appropriate sensors configuration and strategies for their deployment are required to accurately detect failures in the most critical areas of the structure. Spacecraft structural integrity is subject to a series of prevailing loading due to thermo-structural dynamics and environmental effects from design, manufacturing, launching and operation during their pathways to meet a multitude of objectives under a myriad of requirements and constraints. To that end, the objective of the present paper is to provide an overview on spacecraft structural integrity covering a host of selected concepts, design, methods and engineering to maintain structural integrity of space vehicles and associated sub-structures. In spite of citing examples drawn from small satellite situations under vibro-acoustic and environmental thermal loading, the overriding issues addressed could be extended to more general situations. An infographic is presented to map out the state of affairs to be addressed for structural integrity considerations. [Display omitted] The present paper is to provide an overview on spacecraft structural integrity covering a host of selected concepts, design, methods and engineering to maintain structural integrity of space vehicles and associated sub-structures, subject to a series of prevailing loading due to thermo-structural dynamics and environmental effects from design, manufacturing, launching and operation during their pathways to meet a multitude of objectives under a myriad of requirements and constraints, such as various loading and environmental effects. The Rationale and Key Technical Structural Integrity Challenge are first identified. In spite of citing examples drawn from small satellite situations under vibro-acoustic and environmental thermal loading, the overriding issues addressed could be extended to more general situations. An infographic is presented to map out the state of affairs to be addressed for structural integrity considerations. [ABSTRACT FROM AUTHOR]

Lunar exploration is deemed crucial for uncovering the origins of the Earth-Moon system and is the first step for advancing humanity's exploration of deep space. Over the past decade, the Chinese Lunar Exploration Program (CLEP), also known as the Chang'e (CE) Project, has achieved remarkable milestones. It has successfully developed and demonstrated the engineering capability required to reach and return from the lunar surface. Notably, the CE Project has made historic firsts with the landing and on-site exploration of the far side of the Moon, along with the collection of the youngest volcanic samples from the Procellarum KREEP Terrane. These achievements have significantly enhanced our understanding of lunar evolution. Building on this success, China has proposed an ambitious crewed lunar exploration strategy, aiming to return to the Moon for scientific exploration and utilization. This plan encompasses two primary phases: the first crewed lunar landing and exploration, followed by a thousand-kilometer scale scientific expedition to construct a geological cross-section across the lunar surface. Recognizing the limitations of current lunar exploration efforts and China's engineering and technical capabilities, this paper explores the benefits of crewed lunar exploration while leveraging synergies with robotic exploration. The study refines fundamental lunar scientific questions that could lead to significant breakthroughs, considering the respective engineering and technological requirements. This research lays a crucial foundation for defining the objectives of future lunar exploration, emphasizing the importance of crewed missions and offering insights into potential advancements in lunar science. [ABSTRACT FROM AUTHOR]

A long-duration microgravity environment has numerous detrimental effects on the human physiology. The most obvious solution for this problem related to long duration space exploration missions is to remedy the lack of gravity. This could be done using short arm human centrifuges but they do not seem to be sufficiently effective, perhaps because of the short duration exposure of this countermeasure and/or the huge body gravity gradient. New views have to be investigated, such as to see if a (very) long-arm rotating system generating a continuous 1 g or partial gravity field might resolve this issue. Besides the expected benefits regarding astronauts' microgravity pathologies, additionally the spacecraft itself, its on-board (sub-)systems and procedures might benefit from a rotating configuration. In this paper we address very briefly the medical issues, but the work is mainly focused on the advantages regarding engineering, operations, life support, safety and budget of having a constantly rotating spacecraft first in Low Earth Orbit and later for long duration missions to Mars. A large rotating spacecraft is feasible and affordable to build, operate and maintain. It has advantages for governmental and commercial use but also in light of the expected increase in space tourism. It will also save crew time and billions of dollars now being spent to counteract the effects of microgravity. A continuous rotating spacecraft providing Artificial Gravity will: • Improve crew health and wellbeing. • Improve mission safety and success. • Reduce costs significantly. • Simplify numerous operations in flight. • Provides the use of 1 g verified systems. [ABSTRACT FROM AUTHOR]

NASA HRP considers developing radiation protection for human space flight and surface habitation as one of the critical technologies for successful deep space exploration. Although the danger of radiation exposure is recognized as a potential show-stopper for deep space exploration, and radiation effects on humans are now understood better than before, shielding strategies for different stages of space flight and habitation are still not addressed in a fully comprehensive manner. Habitats and all space structures planning and design are guided by essential requirements and constraints associated with safety, manufacturing and assembly procedures, propellant and construction costs, maintenance, crew and/or passenger satisfaction. This paper reviews radiation shielding options for space habitats and discusses their feasibility in relation to habitability needs, including the potential for outside viewing in distinct types of space habitats. Typically, radiation protection depends on the thickness of the exterior structure that consists of a pressurized shell, multilayer insulation (MLI) and any applied radiation shielding material. The mass of the external protection shell is the primary factor of radiation shielding effectiveness. Nevertheless, using materials with low atomic numbers (e.g., Boron (5), Carbon (6), and H 2 O) helps to lower secondary radiation hazards. Water, which is rich in hydrogen and has the lowest atomic number, can also be used for other mission needs. Other materials, including biomaterials, can be considered when their inclusion in the structure is possible and appropriate. The paper presents a comprehensive strategy for radiation shielding selection that includes investigation of complications associated with a type of space habitat structure, mission needs, duration, destination, and crew requirements. The approach presented in the paper aims to establish an evaluation methodology for defining the feasibility of the integration of diverse radiation shielding types into habitat structures. The paper summarizes by reviewing radiation shielding proposals with selected case studies including water, regolith, hydrogen-rich polymers, biotechnology, polyethylene/boron nitride composites, and active strategies. • Case studies of different materials and methods used for radiation shielding purposes, • Pros and cons of using referenced materials and methods in habitat architectures • Criteria for evaluation and selection of appropriate radiation protection strategy • Comparisons of radiation shielding methods by space architecture categories • Comparisons of radiation shielding methods by structural integration options [ABSTRACT FROM AUTHOR]

The major purpose of this paper is to study the important role of historical painting art on the creation of space-age era eight decades ago in 1950s. According to the Merriam-Webster Dictionary , the first known use of "space age" was in 1946. In the Collins Dictionary , the space age is the present period in the history of the world when travel in space has become possible, and people use "space-age" to describe something that is very modern and makes you think of the technology of the space age. In American English, space age is the period in modern history characterized by space exploration, usually considered as beginning on October 4, 1957, when the Soviet Union launched the first artificial satellite, Sputnik I, into orbit around the Earth. In the ancient time, many artists including Giovanni di Paolo, Albrecht Dürer, Étienne Léopold Trouvelot and Vincent van Gogh created masterpieces of space related paintings. Even in the extreme ancient era, the cave art already evidenced humans' astronomical knowledge. Besides the technological research and development for space explorations, groups of workers and artists in the areas of culture, painting, architects, installation artwork, etc. had done many contributions in the development of space-age cultural and aesthetic art before 1950s. They not only created so many masterpieces with plenty of space-age aesthetics, but witnessed and recorded the development history of the space age. It goes without doubt that historical space painting art played an important role on the creation of space-age era in 1950s. Therefore, it is mandatory to investigate and reveal the fact. • To study the important role of historical painting art on the creation of space-age era eight decades ago in 1950s. • The first known use of "space age" was in 1946, considered as beginning on October 4, 1957 when Sputnik I launched. • Giovanni di Paolo, Albrecht Dürer, Étienne Léopold Trouvelot and Vincent van Gogh created masterpieces of space related paintings. • In the extreme ancient era, the cave art already evidenced humans' astronomical knowledge. • Groups of artists in the areas of culture, painting, architects, etc. contributed space-age cultural and aesthetic art before 1950s. • Historical space painting art played an important role on the creation of space-age era in 1950s. [ABSTRACT FROM AUTHOR]

A comprehensive approach to creating a control system for the shape of the radio-reflecting surface of a large-size space reflector is considered. Large-aperture space antennas are used for satellite communications and space exploration. The design of these structures is one of the most promising areas. Ensuring the specified characteristics of the reflector is directly related to maintaining the specified shape of the radio-reflective netting. Developing a control system for the shape of the active antenna surface is an urgent task. Optimizing this process makes it possible to accomplish the mission during the operational period effectively. The paper evaluates the effects of perturbations on a large-scale structure operating in outer space. A method for adjusting the geometry of the frontal network is proposed. This allows for improved communication between spacecraft and ground stations, which is very important for the safety of space flights. The conductive parts of the reflector are considered to transmit energy and control signals to the actuators. The application results of various control algorithms of the executive device making it possible to correct the netting considering the minimization of energy costs and oscillations of the structure are shown. According to the simulation results, the optimal algorithm of the target criteria hierarchy showed greater stability in terms of convergence in the presence of measurement noise and disturbances, which allows it to be applied in real time. This algorithm is supposed to be used in the future when creating a prototype of the system for controlling the shape of the radio-reflective surface of a large-size space reflector using its current-conducting structural parts. • The design of a system for setting up and maintaining a radio-reflective network fabric has been developed. • Algorithms are developed to minimize energy when setting up a radio-reflective mesh. • The optimal algorithm of the control allows solving the problem in real time. • The method for transmitting energy and control signals through the use of conductive structural parts of the reflector is proposed. [ABSTRACT FROM AUTHOR]

The continuous advancement in the space industry and in space access has opened the doors to greater global participation and exploration, with numerous nations, institutes and companies now actively engaged in space exploration. This expansion owes much to the progress in commercial space technologies, such as reusable launch vehicles and micro satellites, which have significantly reduced the overall costs associated with space missions, thereby enhancing space accessibility. Nevertheless, to foster further growth, it is necessary to look at further options of making space access more sustainable and cost-effective. For that, it is important to investigate and identify the cost drivers. An example is the use of traditional manufacturing techniques and materials, which come with inherent limitations, notably in terms of design flexibility and performance efficiency. This results in solutions that are not only time-consuming to manufacture but also not the most effective, making it a costly process. To address these challenges, increasing emphasis is being placed on utilising alternative manufacturing methods, such as additive manufacturing technologies combined with high-performance ceramic materials. This aims to reduce the overall number of manufacturing steps for producing a component and to optimise complex and functional parts reducing the overall costs of mass-produced or individually manufactured components, as evident in current studies. The primary objective of this study is to enhance space accessibility through the development, production and optimisation of electrically functional, all-ceramic and multi-material components (heating/ignition elements). For that, the AM technology "CerAM MMJ" in combination with high performance ceramic material are utilised and discussed. Subsequently, these components undergo electrical measurements and tests, and the resulting data is presented and analysed in the following sections. The findings aim to shed light on the current state of the art and whether the additively manufactured, fully ceramic and electrically functional components could represent a more cost-effective alternative to conventionally manufactured components in the future. • Insight into additive manufacturing technology: Multi Material Jetting (CerAM MMJ) • State of art and AM of all-ceramic, and electrical functional components • Electrical characteristics and performance of ceramic heating and ignition elements • Enhancing space-accessibility through enhanced all ceramic, electric functional parts • Utilizing AM for ceramics to optimize production of mission-critical parts • Utilizing high performance ceramic materials [ABSTRACT FROM AUTHOR]

• This review is the first to combine the materials, energy, and habitation requirements that astronauts require while residing at a lunar base. • It analyses the theories and technologies needed to meet these demands, their advantages and disadvantages, and combinations of different technologies to construct a lunar base that meets production requirements. • Quantitative comparison of the production capacity of in-situ lunar resource production technology. • This review provides some suggestions for phased planning and construction of lunar bases. Establishing a lunar base is a critical goal for many aerospace powers. To achieve this goal, various resources such as life support materials, energy, and shelter are required. However, current research only focuses on the methods for collecting materials and the corresponding technologies required for lunar bases without comparing their advantages and disadvantages. Therefore, it is essential to conduct a comprehensive and concise literature review of current research. This review should discuss in detail the fundamental materials and energy requirements for astronauts living in a long-term lunar base and the specific means to meet those demands. The review should begin with the development process of human spaceflight life-support systems and highlight the limitations of transporting survival materials from Earth. The review emphasises the importance of utilising in-situ lunar resources. This review is the first to combine the materials, energy, and habitation requirements for astronauts residing at a lunar base. It analyses the theories and technologies necessary to meet these demands, their advantages and disadvantages, and how different technologies can be combined to construct a lunar base that meets production requirements. The aim of this review is to provide researchers in a specific field with a comprehensive understanding of the factors to consider when developing a lunar habitat, thus facilitating future research. [ABSTRACT FROM AUTHOR]

A solar sail presents a flat low areal density membrane and is an example of propellant-less propulsion system for the future space exploration. To date, the study of sail membrane deployment strategies is of considerable importance. In this work we present a general theoretical approach to deployment of solar sail of circular shape. We consider a system of a circular membrane attached to a toroidal rim under a force uniformly distributed along the rim's circumference. The stress and strain of the system required for the successful deployment and mechanical stability of the sail are considered in deployed static configuration. Three examples of the deployment force of different nature are presented: magnetic, electric, and the pressurized gas. We give limitations for the solar sail radius for each considered force. [ABSTRACT FROM AUTHOR]

• CeBr 3 and NaI (Tl) scintillators characterized with array of Silicon Photomultipliers. • Energy resolution improves with lower shaping time and higher SiPM over-voltage. • Temperature dependency of gain of SiPM array: ∼−0.81 %/°C for overvoltage of 2.5 Volts. • Temperature dependency of light yield for CeBr 3 : ∼−0.27 %/°C for −31 °C to +26 °C. • Temperature dependency of light yield for NaI (Tl): ∼+0.5 %/°C for −31 °C to +26 °C. Interaction of X-rays with a scintillation detector produces optical photons in the visible range. The spectral and spatial information of the X-ray can be derived by detecting these output photons using a Silicon Photomultiplier (SiPM). Two types of detector modules: CeBr 3 and NaI (Tl), coupled with an array of SiPM are presented here, which are being developed for the future space exploration programs. The development of the front end electronics (FEE) for the charge readout from SiPM for X-ray spectrometer application is presented here which is characterized for SiPM's over-voltages and shaping amplifier's time constant. In this article, both the detector modules are subjected to a wide temperature range to establish a relationship of the SiPM's gain, energy resolution and scintillators' output photon yield with ambient temperature. The test results show that energy resolution improves with higher over-voltage of SiPM and also with lower operating temperature. The gain of the SiPM array shows negative temperature dependence of ∼−0.81 %/°C for an over-voltage of 2.5 Volts. To derive the temperature dependency of scintillators' output photons, gain of the SiPM array was made constant by operating it at a fixed over-voltage for a wide temperature range. With the constant gain of SiPM, CeBr 3 scintillator shows negative temperature coefficient of ∼−0.27 %/°C and NaI (Tl) shows positive temperature coefficient of ∼+0.5 %/°C for the light output in the temperature range of −31 °C to +26 °C. [ABSTRACT FROM AUTHOR]

Wheeled Mobile Robots (WMRs) are systems with applications in diverse fields such as transportation, civilian services, military use, and space exploration. Then, their use will continue increasing, making WMRs an essential research topic that deserves further study. To this end, this work presents a novel observer-based finite-time controller for trajectory tracking control of WMRs disturbed by kinematic disturbances. In the proposed approach, the kinematic model of the WMR is transformed into a set of two decoupled second-order systems. Then, the proposed controller is divided into two parts. The first one employs an observer to estimate the effect of the kinematic disturbances. The second part consists of a finite-time controller designed to achieve finite-time convergence of the tracking error. A detailed synthesis procedure theoretically demonstrates the feasibility of the proposed controller. Subsequently, the proposed scheme is compared against finite-time, feedback, and H ∞ controllers. Exhaustive numerical simulations show that the proposed new control methodology achieves the trajectory tracking objective despite kinematic disturbances and outperforms the other control procedures. Finally, some comments and numerical results are given to clarify how the proposed control methodology can be used to design new controllers for trajectory tracking in WMRs and demonstrate that the new proposal remains to have a good performance when the system's coordinates are corrupted by measurement noise. [Display omitted] • A new observer-based finite-time control for wheeled mobile robots is proposed. • The new control scheme permits achieving the trajectory-tracking task efficiently. • The novel methodology outperforms existing finite-time, feedback, and H ∞ methodologies. • Excellent performance is obtained even in the presence of kinematic disturbances and measurement noise. • The proposed scheme permits the design of new controllers for WMRs easily. [ABSTRACT FROM AUTHOR]

• We introduce a graph theory model and utilize dispatchable STN to address the mission planning problem for deep space detectors. • The proposed algorithm efficiently decreases the network scale and streamline the computational workload. • Our proposed algorithm effectively tackles the challenge of dynamic mission scheduling to effectively handle emergencies. Deep space exploration activities can effectively promote the development and application of space technology, which holds significant scientific and strategic value. The multi-mission and long-period detector is executed in deep space, and numerous temporal constraints are generated by mission planning. Moreover, scheduled missions may face external uncertainties, hindering their smooth execution. Therefore, temporal constraint processing strategies that possess dynamic adjustment capabilities play a crucial role in ensuring the successful execution of deep space detectors. Existing methods primarily concentrate on investigating fixed mission series, with limited efficiency in planning. Specifically, these methods do not rigorously enforce temporal constraints and lack the capability to handle the disruptions caused by emergencies, which hinder the smooth execution of planned missions. In this paper, we propose a dynamic temporal constraints algorithm, aiming to efficiently plan missions subject to temporal constraints and let it possess a certain degree of dynamic adjust capability. The simulation results demonstrate the effective simplification of redundant temporal constraints in mission networks by the proposed algorithm. In comparison to the classical algorithm, the computation time exhibits a clear advantage. Furthermore, the proposed algorithm possesses the capability to perform local, small-scale dynamic adjustments in response to emergencies that may disrupt the normal execution of missions. Consequently, this research establishes a robust basis for addressing temporal constraints in deep space detectors. [ABSTRACT FROM AUTHOR]

Society today is experiencing a golden age of robotic space exploration and interest in human spaceflight has regained popularity as entities like NASA and the burgeoning private space industry refocus attention on sending humans back to the Moon and into orbit. This is a critical turning point for society, as some look to our future as a possibly spacefaring civilization while others wonder who will be enabled to participate in that space exploration. Historically, Disabled individuals and other minoritized groups have been excluded from space science and technology fields, as well as from participation in astronaut programs. However, human space exploration can be made more inclusive with research and innovation in the area of accessible design. Universal accessible design brings advantages to all individuals operating in an environment, and the ability of Disabled individuals to adapt to environments not suited for them can be leveraged as a strength in spaceflight. In this work, disabled and mixed ability crews performed research on parabolic zero-gravity flights which produce weightlessness, exploring tools and technologies which may mitigate challenges for disabled individuals operating in space-like environments. Here we discuss the experiments performed on our flights, highlighting what types of technologies offer promising solutions for accessible design of space habitats, suits, and tools, and accommodations which can enable future disabled astronauts to operate safely in space. We will highlight universal design solutions that not only provide access to previously excluded researchers but have the potential to improve safety and efficiency for all astronauts, regardless of disability. We will also discuss operational strategies which can be incorporated into training and procedure to leverage the strengths of mixed ability crews in ensuring everyone operates effectively together. • Disabled individuals can operate safely and effectively in weightless environments. • Communication and wayfinding are primary challenges to mixed ability crews. • Haptic, light, and tactile technologies offer promising solutions for accessibility. • Redundancy using varied solutions is key to accessible design and operations. • Redesign of emergency response systems are critical for inclusive human spaceflight. [ABSTRACT FROM AUTHOR]

• New method of making lunar permanently shadowed region (PSR) icy regolith simulant. • Lunar PSR icy simulant is a mixture of lunar highlands simulant (LHS) and H2O ice. • Icy simulant can be made in large quantities with variable water ice content. • Icy simulant is granular and has high porosity, which is expected in PSRs. The lunar poles are thought to contain vast ice deposits that could be beneficial to future space exploration efforts. However, it is not well characterized how water ice content affects regolith and dust physical properties. In order to develop suitable technologies that can operate safely in the cryogenic regolith, testing should be conducted in simulated regolith. We present a new production method for lunar permanently shadowed regions (PSRs) icy regolith simulant. We build on an existing lunar highlands simulant, by adapting it for lunar poles, where water ice might be present in PSRs. We have demonstrated a production concept using controllable simulant and water flow rates to make granular icy simulant with variable water ice content. We found that with this production method, icy simulant has a porosity of 0.6 to 0.7, that persists even after dehydration. [ABSTRACT FROM AUTHOR]

• Shared camera measurements in a dual-agent system for pose estimation using a MEKF. • Stereo-vision measurements remove range ambiguity for relative pose estimation. • Relative navigation estimation accuracy improves for proximity operations using stereo-vision measurements. This paper presents a novel autonomous relative navigation architecture for inspector spacecraft in proximity operations to a known structure in a lunar orbit. Autonomous on-orbit servicing and assembly of large space structures are at the forefront of research for advancing space exploration beyond low-earth orbit. Communication delays with ground stations and limited computational power located on the inspector spacecraft make current relative navigation methods unfeasible and in turn, make it difficult to maintain an accurate estimate of the relative position and orientation of the inspector spacecraft with respect to the structure. The proposed method utilizes the camera measurements from two identical inspector spacecraft, each equipped with a single camera, to estimate the relative position and orientation of the structure. This shared measurement strategy overcomes the deficiencies in monocular vision-based relative navigation techniques, such as the range ambiguities, as is proven in the simulated results of this paper. The proposed stereo-vision system in this work allows for a deterministic solution of the relative position and orientation from the measurements of each inspector spacecraft to the structure. The stereo-vision system was tested with a Multiplicative Extended Kalman Filter (MEKF) for each spacecraft to estimate the relative states of the structure while maintaining a fixed relative position to the structure. The performance of the proposed stereo-vision system was evaluated in terms of accuracy and reliability of the estimated relative position and orientation of two inspector spacecraft to the structure over 100 Monte Carlo simulations for three case studies. The results showed that the stereo-vision system significantly outperforms the monocular vision system even when fewer points on the structure are visible, as is the case for proximity operations. Additionally, the stereo-vision system is consistently more accurate for the relative velocity, attitude, and angular velocity states regardless of how many points are visible. The proposed stereo-vision relative navigation system has the potential to be applied autonomously in proximity operations of spacecraft for various space missions, such as rendezvous and docking, inspection, and on-orbit servicing. [ABSTRACT FROM AUTHOR]

Human exploratory missions to Moon or Mars are considered the next steps in human space exploration. Such activities result in the exposure of humans to the space environment for long time, especially under the constraints of orbital dynamics as with increasing distances from earth quick return possibilities are ruled out. Crews on these kinds of missions must be self-sustaining in medical treatments, as environmental conditions in space, such as the influence of altered gravity, radiation or isolation, raise health issues. Therefore, astronauts may use the here presented Handheld Bioprinter as part of the first-aid strategy for in situ wound treatment. The device consists of a handle capable of holding an exchangeable "Ink Printing Unit" containing two separate gel-like components (Bioink and Crosslinker), which are extruded during a printing process through a nozzle and form a skin-cell containing bioink band-aid. For ISS experiments cell simulants were used, as in-space experiments first demonstrated the general feasibility of handheld bioprinting under space conditions. On-ground human skin cells were mixed with the biogel, printed via the handheld bioprinter and cultivated, to demonstrate the overall feasibility of the "Bioprint FirstAid" technology. Concluding results were that a mobile, handheld tool like the bioprinter shows good applicability and offers a possibility of in situ wound treatment for in-space applications. The "Bioprint FirstAid" project was coordinated by the German Space Agency at the German Aerospace Center (DLR) in Bonn and funded by the Federal Ministry for Economic Affairs and Climate Action (BMWK). • Handheld Bioprinter offers possibility for in-situ wound treatment in future in-space applications • Human skin cells proliferate in biogels after printing with handheld bioprinter • The customizable Ink-printing unit and nozzle can be tailored to specific printing demands • Bioprinter device has low susceptibility to failure, has a robust design, no electronics, and maintenance-free mechanics • German Astronaut Matthias Maurer conducted the Bioprinting experiment successfully on board the ISS [ABSTRACT FROM AUTHOR]

Leveraging advancements in micro-scale technology, we propose a fleet of autonomous, low-cost, small solar sails for interplanetary exploration. The Berkeley Low-cost Interplanetary Solar Sail (BLISS) project aims to utilize small-scale technologies to create a fleet of tiny interplanetary spacecraft for rapid, low-cost exploration of the inner solar system. This paper describes the hardware required to build a ∼10 g spacecraft using a 1 m2 solar sail steered by micro-electromechanical systems (MEMS) inchworm actuators. The trajectory control to a NEO, here 101955 Bennu, is detailed along with the low-level actuation control of the solar sail and the specifications of proposed onboard communication and computation. Two other applications are also shortly considered: sample return from dozens of Jupiter-family comets and cometary nuclei imaging. The paper concludes by discussing the fundamental scaling limits and future directions for steerable autonomous miniature solar sails with onboard custom computers and sensors. • An autonomous 10−2 kg spacecraft to navigate the solar system is proposed. • Low-cost spacecraft composed of mostly off-the-shelf parts to return images of NEOs. • Propelled by a 1 m2 solar sail controlled by micro-electromechanical systems motors. • Autonomous trajectory control to a NEO, communication, and computation is detailed. [ABSTRACT FROM AUTHOR]

NASA has encouraged studies on 226Ra deposition in the human brain to investigate the effects of exposure to alpha particles with high linear energy transfer, which could mimic some of the exposure astronauts face during space travel. However, this approach was criticized, noting that radium is a bone-seeker and accumulates in the skull, which means that the radiation dose from alpha particles emitted by 226Ra would be heavily concentrated in areas close to cranial bones rather than uniformly distributed throughout the brain. In the high background radiation areas of Ramsar, Iran, extremely high levels of 226Ra in soil contribute to a large proportion of the inhabitants' radiation exposure. A prospective study on Ramsar residents with a calcium-rich diet was conducted to improve the dose uniformity due to 226Ra throughout the cerebral and cerebellar parenchyma. The study found that exposure of the human brain to alpha particles did not significantly affect working memory but was significantly associated with increased reaction times. This finding is crucial because astronauts on deep space missions may face similar cognitive impairments due to exposure to high charge and energy particles. The current study was aimed to evaluate the validity of the terrestrial model using the Geant4 Monte Carlo toolkit to simulate the interactions of alpha particles and representative cosmic ray particles, acknowledging that these radiation types are only a subset of the complete space radiation environment. [ABSTRACT FROM AUTHOR]

Satellite constellations are widely used for communication, navigation, and Earth observation purposes. They provide good ground coverages and serve better for these needs. Of all the configurations, the Walker constellation is extensively applied in many navigation satellite systems and some low Earth orbit communication constellations, since it can be easily designed and has good coverage. Despite of these advantages, the satellites in Walker constellation generally have different ground tracks. When multiple Walker constellations are to be coordinated, in terms that the orbital planes precess synchronously with the same satellite mean motion Ω 1 , the semi-major axes a of these Walker constellations would be significantly different even when the orbital inclinations differ by a small amount. The Space Exploration Corp (SpaceX) claimed a new constellation design in a patent for their multi-shell Starlink satellite constellation. Constellation shells with different inclinations have small altitude differences, which facilitates regulatory approval and deployment. Satellites in the same shell can also be easily designed to share the same ground track. Although they claimed these features in the patent, SpaceX shared little technical details regarding how to design these constellations. Here in this paper, we analyze the features of the Starlink constellation, and try to find a practical approach to design a Starlink-like constellation, as well as how to determine the rules for inter-satellite links within the constellation. [ABSTRACT FROM AUTHOR]