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Design for Space Architecture Maintainability: Applications of Quantitative and Qualitative Metrics
Get PDFTakaharu Igarashi, Purdue University, United StatesKaren Marais, Purdue University, United StatesICES502: Space ArchitectureThe 54th International Conference on Environmental Systems was held in Prague, Czechia, on 13 July 2025 through 17 July 2025.Maintainability of space systems—the ease and rapidity with
which systems can be preserved against failure or restored
to operational status—has often not been a primary design
consideration and has consistently remained an issue,
frequently addressed too late in design cycles to be fully
considered. Design for Maintainability (DfM) is a strategy
that encompasses principles and measures implemented during
planning and design to ensure ease, safety, and
cost-effectiveness in maintenance. DfM is particularly
critical in extraterrestrial settings, where space
architecture and deep space systems must rely on onboard
maintenance with little to no ground support. Aiming to
examine the applicability of DfM in space architecture and
explore its path forward, this paper outlines the scope of
maintenance activities in space architecture and reviews
both qualitative and quantitative maintainability metrics
in the literature. Based on a consolidated list of
qualitative maintainability attributes identified across
domains, this paper presents examples of design concepts
and features embodying these attributes, demonstrating
their applicability to space architecture through an
illustrative surface habitat design concept. The review of
quantitative maintainability indicators underscores the
challenges of applying such metrics at early stages of
design for novel and unprecedented systems. This paper
further discusses the synergy and conflict among these
attributes, an area with limited discussion in the
literature, and explores examples of both synergistic and
conflicting relationships, as well as their nuanced
interplays depending on the design approach. In addition to
advancing the effort of implementing integrated design
processes that employ quantitative metrics across teams and
organizations for trade studies in early design phases,
this paper concludes by emphasizing the integration of
qualitative maintainability attributes into system
development processes, backed by the potential of
data-based design recommendations and matrix-based methods
for mapping attributes to functional requirements and
design features, resolving conflicts, and facilitating
synergy among them
Carbon Dioxide Deposition for Removal of Volatile Organic Compounds (CDep VOC)
Get PDFGrace Belancik, NASA Ames Research Center (ARC), United StatesMarian Alcid, NASA Ames Research Center (ARC), United StatesPranav Jagtap, Amentum / NASA Ames Research Center (ARC), United StatesSofia Fanourakis, Seabrook Solutions, LLC / NASA Ames Research Center (ARC), United StatesICES302: Physico-Chemical Life Support- Air Revitalization
Systems -Technology and Process DevelopmentThe 54th International Conference on Environmental Systems was held in Prague, Czechia, on 13 July 2025 through 17 July 2025.Atmospheric management for space missions requires an
integrated workflow of carbon dioxide (CO2) removal and
conversion. The CO2 removal system can trap and concentrate
specific volatile organic compounds (VOCs) in spacecraft
cabin air along with carbon dioxide. These VOC
contaminants, namely carbon disulfide, carbonyl sulfide,
and octafluoropropane, can be detrimental when using
catalytic packed beds for oxygen recovery, affecting
performance and lifetime. Therefore, a VOC mitigation
system between the CO2 removal and CO2 conversion system is
required to purify the CO2. Cold surface generation via
cryocoolers can separate CO2 from VOCs due to the
deposition and sublimation temperature differences between
the species. NASA Ames Research Center has been developing
CO2 cold surface deposition (CDep) technology for CO2
capture from air. This technology was adapted into a new
test system for VOC mitigation to remove contaminants from
captured CO2, dubbed CDep VOC. Design of the full-scale
benchtop test has been completed, and the build is in
progress, with the goal to achieve successful separation of
trace VOCs from CO2 as well as passive pressurization for
immediate use in an oxygen recovery system
Gateway’s Habitation and Logistics Outpost (HALO) Environmental Control and Life Support System (ECLSS) Concept of Operations Overview
Get PDFMarta Stepanyuk, Northrop Grumman Corporation, United StatesAaron Stirk, Northrop Grumman Corporation, United StatesChanon Stewart, Northrop Grumman Corporation, United StatesICES506: Human Exploration Beyond Low Earth Orbit: Missions
and TechnologiesThe 54th International Conference on Environmental Systems was held in Prague, Czechia, on 13 July 2025 through 17 July 2025.This Concept of Operations (ConOps) overview paper will
detail Gateway’s Habitation and Logistics Outpost (HALO)
mission timeline, the first and core component of Gateway.
Gateway is a pivotal element of NASA’s Artemis program
which aims to establish a sustainable human presence in
lunar orbit, support boots-on-the-moon lunar operations,
and facilitate further research and expansion for crewed
missions to Mars and beyond. This overview will outline
HALO’s mission objectives and will address each phase of
flight from launch to deorbit, focusing on HALO’s advanced
life support system, integration of autonomous systems for
maintenance and operation, and impact for a sustained human
presence on the moon. It will also detail how the ConOps
impacted the design and overall mission architecture, as
well as implications for other HALO interfacing vehicles.
Ultimately, this paper aims to provide a clear
understanding of the operational framework of HALO’s
mission as well as highlighting how HALO serves as critical
infrastructure for lunar exploration and beyond
The effect of training paradigm on dogs’ (Canis familiaris) acquisition and generalization of smokeless powders
No full textExplosives detection canines need to be trained to detect a range of energetic variations at an efficient scale to meet the needs of public safety. The goal of this study was to determine which of three training paradigms most efficiently trained canines to detect eight smokeless powder (SP) varieties and to generalize to novel SP exemplars. Three training paradigms were compared: Sequential (dogs were trained to one odor at a time), Mixture (dogs were trained to a mixture of four SPs), and Inter-mixed (dogs were trained to four unmixed SPs within a session). SPME GC-MS was used to evaluate the volatile organic compound (VOC) profile of 18 SPs. We then identified four SPs that showed maximal VOC profile variation as the initial training targets and four related variants. The training paradigm had no effect on acquisition time. One anomalous SP was observed, where 12 of 18 dogs failed to reach criterion. Inter-mixed training led to higher rates of generalization across 10 untrained SP varieties compared to Sequential and Mixture training. Mixture and Sequential trained dogs did not differ in their generalization rates. Although Inter-mixed training led to higher rates of generalization, it did not produce proficiency in detection of all novel variants, with many variants (double and single base) producing < 75 % response rates. Explicit training with some variants is still required with Inter-mixed training. A Partial Least Squares Regression (PLS), where the SPME GC/MS VOC peak areas for each detected VOC were used to predict canine nose hold time, explained 72 % of the variance in VOC data and 17 % of the variance in cumulative nose hold time. The VOCs with the highest variable importance was one VOC unique to Vihta Vuori® single bases, and two VOCs associated with Hodgdon® single bases, to which dogs showed poor generalization. Good to adequate generalization was observed across Hodgdon® double bases and Accurate® single and double bases. Overall, these results suggest that Inter-mixed training has important benefits in generalization; however, explicit training is needed to reach proficiency
Challenges in Improving the Operational Efficiency of Two-Phase Heat Transfer Systems in Space
No full textRustem Turna, Center of Technical Physics Sp. z o.o., PolandGennadiy Gorbenko, Center of Technical Physics Sp. z o.o., PolandOleksii Buchko, Center of Technical Physics Sp. z o.o., PolandYevhen Rohoviy, Center of Technical Physics Sp. z o.o., PolandICES201: Two-Phase Thermal Control TechnologyThe 54th International Conference on Environmental Systems was held in Prague, Czechia, on 13 July 2025 through 17 July 2025.For high-power spacecraft with extensive heat transfer
distances, thermal control systems based on mechanically
pumped two-phase loops (2ph-MPL) offer a highly effective
solution. The development of these systems began in the
1980s, yet the first high-power satellites equipped with
2ph-MPLs by Thales Alenia Space-France were only launched
in 2021-2022. Despite this progress, there is substantial
potential to enhance the efficiency and reliability of
2ph-MPL technology. This report addresses several key
challenges and presents preliminary research findings that
could further advance the capabilities of 2ph-MPLs: 1)
Pressure regulation and cavitation prevention: A
heat-controlled accumulator (HCA) is used to regulate
pressure within the loop, maintaining the working fluid's
boiling point or ensuring a sufficient cavitation margin at
the pump inlet. This report discusses a method for
determining the required HCA volume and examines 2ph-MPL
performance under critical operating conditions, where
pressure control may become compromised. 2) Impact of
non-condensable gases (NCGs): During the operation of an
ammonia-based loop, non-condensable gases can accumulate
due to radiolysis. Experimental and theoretical approaches
were employed to assess the impact of NCGs on loop
performance. 3) Hysteresis-induced overheating: When the
heat load is activated, abnormal and prolonged overheating
of payloads may occur due to a hysteresis effect, which
requires significant wall overheating of the cold plate to
initiate boiling. This report provides recommendations to
mitigate this issue. 4) Component design and optimization:
The design of 2ph-MPL components requires balancing
numerous technical factors and parameters to achieve
optimal performance. A methodology for multi-criteria,
multi-parameter optimization is presented, including an
example of its application in designing a satellite heat
rejection subsystem with minimal mass per unit of
dissipated power
Pandemic perspectives: the temporal influence of COVID-19 on attitudes toward marriage and childbirth
No full textIntroduction: Marriage and childbirth rates in the U.S. have declined over the past decade, with individuals delaying these life milestones. The COVID-19 pandemic further complicated these trends, simultaneously increasing the desire for connection while disrupting relationship formation. This study examines how perceptions of marriage and childbearing shifted during the first two years of the pandemic using two cross-sectional, nationally representative surveys. Methods: Study 1 (n = 513), conducted in January 2021, and Study 2 (n = 1,850), conducted in August 2022, surveyed participants on the perceived importance of marriage and childbearing before and during the pandemic. Data were collected through online surveys and analyzed using linear regressions to identify demographic differences and shifts in attitudes. Results: Study 1 (n = 513) in January 2021 found that approximately 29% reported a decreased importance of marriage, while nearly 35% reported a reduced importance of child-bearing. Women and those with higher income reported an increase in the importance of marriage, while those with higher income reported an increase in the importance of having children. Study 2 (n = 1850) in August 2022 revealed a noteworthy contrast. Overall, participants expressed a consistent desire for marriage compared to pre-pandemic levels. Conversely, participants demonstrated a significant shift in their desire for children, indicating a greater inclination toward childlessness compared to pre-pandemic attitudes. 15.1% reported a reduced importance of having children. Higher income participants rated marriage as more important, while heterosexual participants rated having children as more important relative to pre-pandemic years. Discussion: These results underscore the dynamic nature of individuals’ perceptions surrounding marriage and childbearing in response to a transformative event like the COVID-19 pandemic. They provide valuable insights into the evolving cultural narrative around these milestones, highlighting the resilience and adaptability of societal values in the face of unprecedented change
Methods for quantifying changes to Lesser Prairie-Chicken lek connectivity and habitat
No full textLesser prairie-chickens (Tympanuchus pallidicinctus) are an endangered bird of the Southern Great Plains (USA). They use spatially explicit locations called leks for reproductive activities; these leks manifest as a habitat network that females traverse to select mates. As the prairie-chicken population has declined in recent decades, leks have been abandoned, resulting in diminished connectivity that may further exacerbate declines. In this thesis, I examined how graph-theoretic multiscale connectivity was indicative of spatial patterns of lek persistence and decline through time. Additionally, because the connectivity of the prairie-chicken habitat network is thought to be negatively affected by woody plant encroachment, I developed a new workflow for using remotely sensed imagery to identify honey mesquite (Neltuma [=Prosopis] glandulosa) on the landscape; this work is published in the International Journal of Applied Earth Observation and Geoinformation (volume 136, article 104362, 2025).
The prairie-chicken lek network represents a prime testing ground for examining how analyses of connectivity may help inform why and where population declines occur, which may be useful for predictive and preventative management. I compared how patterns of decline and abandonment may be associated with lek structural connectivity. I used data on locations and years of recorded activity of leks in the southern population of lesser prairie-chickens. Using the Python package igraph, I generated networks for a series of biologically relevant threshold distances representing a range of dispersal distances. Kleinberg’s hub and betweenness centrality metrics were calculated for each lek at each distance. I used centrality metrics to score each lek based on its contribution to the network, then I weighted the number of years in which lekking behaviors were observed. I also used these scores to build models that can predict whether a lek is active (occupied by lesser-prairie chickens) or not based on centrality score collected at multiple scales. I found that the number of years in which a lek was recorded as being active was positively associated with a lek’s betweenness centrality score and, to a lesser extent, hub score. These associations varied across scales, with leks having high persistence of activity being more central in smaller-scale clusters (maximum nesting distance), and leks known to have failed being less central at broader scales (average and maximum dispersal distances). I also found that centrality score could be used to predict whether a lek was active or not with 80% accuracy. The results of this analysis provide insight into how network connectivity may influence the decline or continued persistence of species reliant on spatially explicit features such as leks. The results of this work may also provide a basis for additional study of environmental factors, such as woody plant encroachment, that may constrain landscape connectivity for species such as lesser prairie-chickens.
Curtailing encroachment is dependent on effectively identifying where problematic species occur. However, traditional classification methods struggle to distinguish spectrally similar species. New remote-sensing techniques that incorporate environmental variables (e.g, edaphic, climatic, and topographic characteristics) into classification can refine predictions and help identify important factors associated with species occurrence. I developed a workflow to improve classification of honey mesquite in the Southern Great Plains, examining 70 environmental variables to determine which were most associated with mesquite presence. I used Google Earth Engine to run X-means clustering on high-resolution aerial imagery from 50 replicate 78-km2 areas in New Mexico and Texas. I then refined the classification using XGBoost to generate accuracy assessment points for each area to confirm locations of mesquite clusters. This method improved classification accuracy from 36% to 83%. I then performed an ex-situ ground-truthed validation study that achieved 74% accuracy. Inclusion of environmental data increased the accuracy of mesquite classification and allowed me to estimate the influence of each variable in determining whether a given point was classified as mesquite. Shallow, alkaline soils with low water-storage capacity, high electrical conductance, and low cation exchange capacity were associated with mesquite presence; these areas tended to be associated with flat, low-elevation drainages in regions that experience wide annual temperature ranges. These methods provide an easily reproducible and scalable way to assist with image classification of rangeland shrubs from remotely sensed imagery, which may prove useful in managing the further encroachment of problematic species like honey mesquite
To what aspect of environmental variability does photosynthesis acclimate?
No full textPhotosynthetic acclimation occurs when plants are exposed to a long-term environmental change and, in response, undergo a biochemical or morphological change. Sensitivity analyses have shown that photosynthetic acclimation can have large impact on simulations of the terrestrial carbon cycle, however, the mechanisms underlying these responses are not fully understood. This uncertainty hinders the inclusion of photosynthetic acclimation in models. Here, I addressed one aspect of this uncertainty by quantifying how photosynthetic acclimation responds to different levels of temperature and light variability. Specifically, I asked whether plants acclimate to midday or average daily conditions. I utilized Glycine max in a 7-week growth chamber experiment with 4 different variability treatments that all had the same average daily conditions but varied in low/high variability for temperature and light. I found that the treatments did not have a significant effect on measured traits related to photosynthetic biochemistry, morphology, or plant biomass, despite treatments that varied by 5°C and 400 µmol m-2 s-1 PAR during the middle of the day. The only treatment effect I detected was an increase in Narea with increased high light variability (HLV). This indicates that plants in HLV were increasing their nitrogen, not for photosynthesis but possibly for light dissipation. That said, the majority of my findings indicate that plants did not acclimate to aspects of environmental variability. These results, combined with previous studies, suggest that plants acclimate to average conditions because the only similarity between my treatments was the average daily condition. My findings suggest that models should use average conditions to simulate acclimation responses
Food security and sustainable agriculture: examining food self-sufficiency in Nepal amidst high rates of migration
No full textThe emergence of global food trade has ameliorated food insecurity in several countries including the reliance on food imports to meet the dietary needs of a country’s population. One factor that can affect domestic food production and food security is migration. Several studies have suggested that unprecedented high rates of migration from agricultural areas in Nepal has contributed to the observed agricultural decline. In fact, some districts in Nepal have experienced up to 40% outmigration and up to one third of the agricultural lands have been abandoned. Thousands of able-bodied men and women between 18 – 24 leave Nepal every day to seek employment in countries in the Middle East, Malaysia, and India. In this study, we evaluate the food system in Nepal and how migration, domestic food production, and trade have evolved over a few decades (1990-2021). Using datasets from the Food and Agriculture Organization (FAO), my thesis analyzes the trends in domestic food production and imports of four main cereals (rice, wheat, maize, and millet which comprise ~70% of the dietary demand in Nepal) and the area of land used to harvest these crops. My research confirms that there has been a decline in the amount of land used for agriculture in Nepal since the 1990s including the increased use of fertilizers in domestic agriculture. I calculated the amount of water and land area that will be required for Nepal to achieve self-sufficiency, i.e., the demand for food is met via domestic food production. In Nepal, 53% more land (km2) and water input (m3) would be needed to achieve self-sufficiency. As the world population grows over the next few decades, my thesis considers the tradeoffs between over reliance on food trade vs. self-sufficiency to ensure food security and sustainable agricultural land and water management for future generations
Red Meat Amino Acids for Beginners: A Narrative Review
No full textMeat is a major source of dietary protein and fat across the globe. Red and white meat are the major terms consumers use to refer to types of meat; however, these terms do not fully encompass the range of nutrients provided by meat sources. Red meat refers to meat from mammalian skeletal muscle, while white meat refers to poultry. Red and white meat both provide a wide range of nutritional components in the context of fatty acids, amino acids and micronutrients. Importantly, it has been demonstrated that amino acid profiles differ between red meat and white meat as well as between different sources of red meat. Red meat is a complete source of dietary amino acids, meaning it contains all essential amino acids (EAAs), and in addition, it contains all the non-essential amino acids (NEAAs). Red meat is also the most abundant source of bioavailable heme-iron essential for muscle growth and cardiovascular health. Red meat has been indicated as a major contributor to the rising incidence of metabolic disorders and even colorectal cancer. However, it is important to note that while red meat consumption is linked to these conditions, it is typically the overconsumption of red meat that is associated with obesity and other metabolic symptoms. Similarly, the preparation of red meat is a key factor in its link to colorectal cancer as some methods of preparation produce carcinogens while others do not. Finally, red meat may also be situationally more beneficial to some groups than others, particularly in the cases of sex and aging. For pregnant women, increases in red meat consumption may be beneficial to increase the intake of semi-essential amino acids, while in the elderly, increases in red meat consumption may better preserve muscle mass compared with other dietary protein sources