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NASA NTRS2026

Spacecraft Water Impurity Monitor, a System for Water Quality Analysis on Exploration Missions Beyond Low Earth Orbit

Exploration missions beyond low-earth-orbit (LEO) will require advanced instrumentation to monitor water quality. Traveling beyond LEO means the transfer of water samples to an Earth-based laboratory for detailed analysis is not feasible. Detailed analysis of water composition during exploration is still necessary, because having the capability to determine the specific organic chemical causing a change in total organic carbon (TOC) or the specific metal or ionic species causing a change in conductivity has the potential to inform the crew health and system management decisions. On a new vehicle such as a lunar or Mars surface habitat or a Mars transit vehicle, finding “new” impurities not seen on ISS should be expected. The key is to identify the impurity so the correct action can be taken. On ISS we can measure TOC, conductivity, and other physical properties but do not have the capability for detailed analysis using vehicle instrumentation. This is acceptable because ISS can send samples down to Earth for further analysis and obtain the detailed composition. The Spacecraft Water Impurity Monitor (SWIM) will provide detailed water quality analysis for missions in which sample down mass is not available. SWIM is a system comprising organic and inorganic analysis modules. For organic chemicals, a gas chromatograph mass spectrometer (GCMS) detects and identifies organic impurities. For inorganic species, a capillary electrophoresis capacitively coupled contactless conductivity detection (CE-C4D) system as well as ion specific electrodes detect and identify metal ions and other inorganic salts / acids. The SWIM technology demonstration project has completed a System Requirements Review (SRR) to finalize detection requirements and is currently working to refine vehicle interface requirements for a future technology demonstration. The project also has begun preliminary flight design activities for the core analyzers in the instrument suite.

Water Monitoring↗

NASA NTRS2014

Commonality between Reduced Gravity and Microgravity Habitats for Long Duration Missions

Many conceptual studies for long duration missions beyond Earth orbit have assumed unique habitat designs for each destination and for transit habitation. This may not be the most effective approach. A variable gravity habitat, one designed for use in microgravity, lunar, Martian, and terrestrial environments may provide savings that offset the loss of environment-specific optimization. However, a brief analysis of selected flown spacecraft and Constellation-era conceptual habitat designs suggests that one cannot simply lift a habitat from one environment and place it in another that it was not designed for without incurring significant human performance compromises. By comparison, a conceptual habitat based on the Skylab II framework but designed specifically to accommodate variable gravity environments can be shown to yield significant advantages while incurring only minimal human performance compromises.

Howard, Robert↗

NASA NTRSDate not supplied

The Need for Earth-Based Experiments to Inform Microbial Evolution on Planetary Surfaces

Introduction: Historically, the focus of planetary protection at NASA has been on unmanned, robotic missions. Such missions have paved the way for understanding how to implement planetary protection in a feasible and cost-sensitive way. However, with the introduction of crewed missions to Mars in the not-sodistant future, there is a need to better define and understand how to implement planetary protection under new circumstances, as well as understand the risk of contaminating Mars. One unavoidable fact is that microbes will go where humans go. Therefore, it is critical to understand how these microbes may (and will) impact our ability to conduct meaningful, reliable astrobiological science. Microorganisms have spent millions of years evolving to survive in extreme environments here on Earth. Already there are indications that microbes aboard the International Space Station evolve and adapt to life in low earth orbit. The microbes that are eventually taken to Mars with humans will also adapt, potentially causing harmful effects to crew and/or the planetary or astrobiological science conducted. Therefore, it is of critical interest that we evaluate and characterize the potential risks of microbial evolution on Mars. It is expected that microbes carried by humans will begin to evolve to new environments even before landing on Mars, during the several month cruise phase. Once landed, microbes will encounter different stressors within the crew habitats on Mars. During extravehicular activities, venting, or other release events, microbes will find their way out onto the Martian surface. The induced environments around crewed systems will create potentially-favorable conditions for microbes to continue evolving on Mars. Eventually, microbes may find their way beyond the close confines of the crewed area and continue evolving so as to fill new or distant niches on the Martian surface. It is challenging to replicate Martian environments here on Earth, making it nearly impossible to predict the evolutionary changes that microbes would undergo on Mars. But this work is critical. Serial passaging experiments performed by Richard Lenski on E. coli show the dramatic changes microbes can undergo even within a laboratory setting. Furthermore, experiments performed by Michael Baym also demonstrate the power of single mutations in microbial development of antibiotic resistance [3]. Long duration experiments should be performed on a suite of microbes exposed to environments likely to be experienced on the Martian surface. While simulating space environments can be challenging, facilities exist that can achieve individual and combinatorial environmental conditions to simulate space and planetary conditions. Such chambers should be employed for microbial studies. Currently, at the Marshall Space Flight Center, we have used various stressors like drying, vacuum, proton radiation, and ultraviolet light both separately and in combination, to evaluate the survival of cleanroom microbes. Shockingly, several non-spore forming isolates have demonstrated the ability to survive many extreme conditions (manuscript in preparation). These short duration exposures must be augmented with larger and more gradual studies to replicate what microbes might experience in the transition from cruise, to surface habitats, to induced surface environments, and finally true Martian environments. While no Earth-based experiment can perfectly replicate the Martian environment, nor could we test every possible microbe in simulation experimental regimes, efforts should be made to examine the evolutionary potential of the “usual suspects” seen on the ISS or in other crewed environments to begin to fill this important knowledge gap.

Chelsi D. Cassilly↗

DOE OSTI2024

Deep learning models map rapid plant species changes from citizen science and remote sensing data

Anthropogenic habitat destruction and climate change are reshaping the geographic distribution of plants worldwide. However, we are still unable to map species shifts at high spatial, temporal, and taxonomic resolution. Here, we develop a deep learning model trained using remote sensing images from California paired with half a million citizen science observations that can map the distribution of over 2,000 plant species. Our model— Deepbiosphere— not only outperforms many common species distribution modeling approaches (AUC 0.95 vs. 0.88) but can map species at up to a few meters resolution and finely delineate plant communities with high accuracy, including the pristine and clear-cut forests of Redwood National Park. These fine-scale predictions can further be used to map the intensity of habitat fragmentation and sharp ecosystem transitions across human-altered landscapes. In addition, from frequent collections of remote sensing data, Deepbiosphere can detect the rapid effects of severe wildfire on plant community composition across a 2-y time period. These findings demonstrate that integrating public earth observations and citizen science with deep learning can pave the way toward automated systems for monitoring biodiversity change in real-time worldwide.

Gillespie, Lauren E.↗

DOE OSTI2021

Characterizing juvenile salmon predation risk during early marine residence

Predation mortality can influence the distribution and abundance of fish populations. While predation is often assessed using direct observations of prey consumption, potential predation can be predicted from co-occurring predator and prey densities under varying environmental conditions. Juvenile Pacific salmon Oncorhynchus spp. (i.e., smolts) from the Columbia River Basin experience elevated mortality during the transition from estuarine to ocean habitat, but a thorough understanding of the role of predation remains incomplete. We used a Holling type II functional response to estimate smolt predation risk based on observations of piscivorous seabirds (sooty shearwater [ Ardenna griseus ] and common murre [ Uria aalge ]) and local densities of alternative prey fish including northern anchovy ( Engraulis mordax ) in Oregon and Washington coastal waters during May and June 2010–2012. We evaluated predation risk relative to the availability of alternative prey and physical factors including turbidity and Columbia River plume area, and compared risk to returns of adult salmon. Seabirds and smolts consistently co-occurred at sampling stations throughout most of the study area (mean = 0.79 ± 0.41, SD), indicating that juvenile salmon are regularly exposed to avian predators during early marine residence. Predation risk for juvenile coho ( Oncorhynchus kisutch ), yearling Chinook salmon ( O . tshawytscha ), and subyearling Chinook salmon was on average 70% lower when alternative prey were present. Predation risk was greater in turbid waters, and decreased as water clarity increased. Juvenile coho and yearling Chinook salmon predation risk was lower when river plume surface areas were greater than 15,000 km 2 , while the opposite was estimated for subyearling Chinook salmon. These results suggest that plume area, turbidity, and forage fish abundance near the mouth of the Columbia River, all of which are influenced by river discharge, are useful indicators of potential juvenile salmon mortality that could inform salmonid management.

Phillips, Elizabeth M. (ORCID:0000000327752563)↗

NASA NTRS1992

Human support for Mars exploration - Issues and approaches

The preparations for a manned mission of the length associated with travel to Mars will strongly focus on the human crew, in order to best support their technical, physical, and psychological needs. Advanced life-support systems for both internal and external operations will be critical in both the transit vehicle and planetary surface habitat. Not only individual systems, but how they mutually interact and in turn affect the crew, will shape not only habitats but realistically foreseeable mission objectives. The long-term habitability of all accommodations will be a far more prominent design criterion than heretofore for the relevant engineering disciplines.

Gross, Anthony R.↗

NASA NTRSDate not supplied

Relevant Environment Additive Construction Technology (REACT)

Project Overview This project is focused on developing technologies that enable construction of a Lunar Safe Haven type structure on the moon. A full scale architectural and structural design will be completed based on lunar conditions and Artemis mission needs. A scaled structure will be 3D printed in simulated lunar environments. Technical Approach Polymer bound regolith composite materials will be developed and characterized for lunar additive construction applications. A full scale architectural and structural design will be completed based on the latest scientific data on lunar environments including radiation, meteoroids, thermal conditions, reduced gravity, and moonquakes. The project will culminate with a demonstration of additive construction in simulated lunar vacuum, thermal, regolith, and UV conditions. Results/Summary Preliminary material specifications have been developed and an initial batch has been produced. A first iteration of the architectural and structural designs have been completed. Hardware for 3D printing in simulated lunar conditions is under development. Contributing Partners AI Space Factory – Winner of the NASA 3D Printed Habitat Centennial Challenge Infusion and Transition Plan On-surface construction of infrastructure is a critical capability of the sustainable phase of the Artemis Program and eventual sustainable human presence on Mars. It provides the ability to create protective shelters on-demand using local resources. The 3D-printing technology will achieve TRL 6 in 1g/vacuum tests with thermal/UV exposure in this project. CLPS missions will be pursued for infusion to demonstrate vertical construction with lunar regolith and conditions. Modeling and simulation will be used to define the pilot-scale shelter construction mission for long-term exposure on the lunar surface to validate the system for Artemis operational deployment.

Lunar Construction↗

NASA NTRS2010

Defining an Abrasion Index for Lunar Surface Systems as a Function of Dust Interaction Modes and Variable Concentration Zones

Unexpected issues were encountered during the Apollo era of lunar exploration due to detrimental abrasion of materials upon exposure to the fine-grained, irregular shaped dust on the surface of the Moon. For critical design features involving contact with the lunar surface and for astronaut safety concerns, operational concepts and dust tolerance must be considered in the early phases of mission planning. To systematically define material selection criteria, dust interaction can be characterized by two-body or three-body abrasion testing, and subcategorically by physical interactions of compression, rolling, sliding and bending representing specific applications within the system. Two-body abrasion occurs when a single particle or asperity slides across a given surface removing or displacing material. Three-body abrasion occurs when multiple particles interact with a solid surface, or in between two surfaces, allowing the abrasives to freely rotate and interact with the material(s), leading to removal or displacement of mass. Different modes of interaction are described in this paper along with corresponding types of tests that can be utilized to evaluate each configuration. In addition to differential modes of abrasion, variable concentrations of dust in different zones can also be considered for a given system design and operational protocol. These zones include: (1) outside the habitat where extensive dust exposure occurs, (2) in a transitional zone such as an airlock or suitport, and (3) inside the habitat or spacesuit with a low particle count. These zones can be used to help define dust interaction frequencies, and corresponding risks to the systems and/or crew can be addressed by appropriate mitigation strategies. An abrasion index is introduced that includes the level of risk, R, the hardness of the mineralogy, H, the severity of the abrasion mode, S, and the frequency of particle interactions, F.

Kobrick, Ryan L.↗

NASA NTRS2021

Population Viability Analysis (PVA) as a Platform for Predicting Outcomes of Management Options for the Florida Scrub-Jay in Brevard County

The Florida scrub-jay (FSJ) is a species in decline because of extinction debt caused by habitat fragmentation and degradation. Understanding and managing the species and its habitats is challenging due to the complex interactions among the social system, a dynamic mosaic of scrub habitat, and active management. To provide insights into the possible fates of the FSJ populations of mainland, cape, and island sections of Brevard County, we modeled the population dynamics using the Vortex population viability analysis (PVA) software. Vortex is an individual-based simulation that allowed us to include such factors as demographic rates dependent on habitat state, impact of helpers on breeding success, and helper to breeder transition probabilities responding to availability of nearby vacant optimal habitat and vacancies due to the death of breeders. Detailed modeling of the FSJ was possible only because a lot of data about the species and its habitats have been gathered over decades of intensive research. We followed a phased approach to constructing population models that incorporated the best available science and data to address a variety of conservation actions. The first phase focused on constructing a model that incorporates sociobiology and source-sink habitat dynamics. This model allowed us to address some of the most important questions about population size and habitat quality. Once the model framework was in place, we considered the real landscapes and actual local populations, rather than just generic representations of typical FSJ dynamics. After examining the viability of the metapopulations under current conditions, we explored the likely consequences of various management actions that might slow or reverse population declines.

Population Viability Analysis↗

NASA NTRS2005

Sabatier Methanation Reactor for Space Exploration

The Sabatier Methanation Reactor technology is of vital importance to the success of the human and robotic exploration program. In order to achieve an affordable program, the logistics supply to support the mission must be minimized to the fullest extent possible. One area of potential reduction with high return on investment is the closure of life support loops, particularly oxygen and water. The Sabatier system accomplishes this by utilizing hydrogen and carbon dioxide, waste products from the life support system, to produce water and methane. The recovered water is then recycled back into the life support system to provide oxygen; while the methane can be used for propulsion, or can be broken down further to recover the hydrogen. This technology is applicable not only to transit phases of exploration, but surface habitats as well as in-situ propellant production. The Sabatier Reactor system has been developed for ground based demonstration experiments extensively over the past 30 years. Over the past three years, NASA has funded development of the Sabatier Carbon Dioxide Reduction Assembly (CRA) for use on the ISS. Currently this system is at TRL 5 and it is expected that the system will be flown on the ISS as a flight experiment, The purpose of the flight experiment is to integrate the Sabatier CRA into a synchronized system with the oxygen generation system and the carbon dioxide concentrator. The flight experiment will verify the integration of the different systems working together plus it will verify the capability of the system to operate, and effectively separate its products in a micro-gravity environment. Subsequent to design validation, the flight experiment can remain onboard the ISS providing valuable water to offset logistics re-supply requirements. Some of the challenges facing the development of the Sabatier system include handling vibration induced particulates, microgravity phase separation and containment of hazardous gases. Plans for adequately addressing these issues will be presented. The Sabatier carbon dioxide reduction process will greatly benefit any of the extended duration human exploration missions because of the tremendous savings of consumables realized. Any of these mission scenarios, be they transit or surface based, must consider closing the life support loops in order to make the mission achievable, let alone affordable. Carbon dioxide reduction technology will be necessary for future outpost habitats, and the technology needs to be proven viable in a space application. The Sabatier methanation reaction is also a desirable method for producing propellant from the Mars atmosphere. The common system could be designed to accept carbon dioxide from an indoor air revitalization loop concentrator, or from an outdoor atmosphere compressor. Carbon dioxide reduction validation is but one step in the spiral development of the in-situ propellant production system desired for future planetary exploration.

Murdoch, Karen↗

NASA NTRS2011

A Dual-Chamber Hybrid Inflatable Suitlock (DCIS) for Planetary Surfaces or Deep Space

The Habitat Demonstration Unit (HDU) Project in conjunction with the NASA Extravehicular Activity (EVA) team has identified a need for a hybrid inflatable and hard shell suitlock that can be used for planetary surface and deep space human exploration missions. Through ongoing analog studies at NASA Desert Research and Technologies Studies (D-RATS) and in NASA's Prototyping Testbed Facility, it has been determined that a compactly stowed, deployable suitlock unit is needed to accommodate advanced EVA egress and ingress operations for various environments with only minor modification.The Dual-Chamber Inflatable Suitlock (DCIS) consists of three hard in-line bulkheads, separating two cylindrical membrane-walled compartments. A dual-compartment suitlock will allow for dust and contaminant control, suit maintenance, and efficient egress / ingress; and the inflatable aspect of the design will allow the unit to stow in a compact package for transport. This paper describes the DCIS functionality, subsystems, and operational scenarios.The novel concepts included in the DCIS are the triple bulkhead, dual-chamber that has one compartment that is continuously pressurized (either at cabin pressure, or may be used for transitional pressure from high-pressure habitats), and a nominal unpressurized second compartment where the suits will be kept for normal operations. The advantages include quicker egress / ingress, capacity for 'shirt sleeve' suit maintenance, and portability of the entire unit.

habitat demonstration unit (HUD)↗

NASA NTRS2018

Preparing for Planetary Surface Exploration by Measuring Habitat Dust Intrusion with Filter Tests During an Analogue Mars Mission

As humans venture deeper into space more issues related to operations will become apparent. While the perils ofdust particles may not be widely recognized, it is one of the major issues astronauts will face on the surface of theMoon and Mars. Dust particles present a problem for both astronaut health and equipment as revealed during theApollo era lunar surface missions. Dust particles cling to spacesuits and field gear, which upon ingress would begincirculating throughout the spacecraft or habitat. An astronaut's health is compromised by the dust particle's potentialto embed in the lungs and cause respiratory illnesses. The extreme abrasiveness and granularity of the particles makeit near impossible to completely shield a spacecraft or habitat from dust related damage. NASA's Glenn ResearchCenter collaborated with Crew 188 at the Mars Desert Research Station (MDRS) in Utah to measure how much dustentered the habitat during a series of extravehicular activities (EVAs), or surface excursions. A NASA GRCdeveloped multistage filter system, coined the Scroll Filter System, was tested, for its effectiveness in removing dustthat entered the airlock and habitat after the EVAs. An optical particle counter measured the ambient airlockparticulates five times including: before the start of operations; after the crew left for EVA; in the middle of the EVAwith the settled air; before the crew entered the airlock after EVA; and finally, after the crew simulated repressurizationand suit brushing off in the airlock. Data was also collected in several of the working environmentlocations around MDRS and outside the habitat in the wind. Data collected from this research will help establishfilter equipment for life support systems and prescribed operations for astronaut transition from a planetary surfaceinto a desired clean habitat. Measurements may aid in updating a baseline expected dust load for a surface habitatand further facilitate the mitigation of astronaut's exposure to dust particles on the surface of celestial bodies.

Kobrick, Ryan L.↗

DOE OSTI2023

AmeriFlux FLUXNET-1F US-xHA NEON Harvard Forest (HARV)

This is the AmeriFlux Management Project (AMP) created FLUXNET-1F version of the carbon flux data for the site US-xHA NEON Harvard Forest (HARV). This is the FLUXNET version of the carbon flux data for the site US-xHA NEON Harvard Forest (HARV) produced by applying the standard ONEFlux (1F) software. Site Description - The Harvard Forest site is comprised of 3,750 acres of land and multiple research facilities; it is the core NEON site for the Northeast region. Harvard Forest is a department of the Faculty of Arts and Sciences of Harvard University. Representative habitats at Harvard Forest include northern, transition, and central forests; marshes, swamps, and conifer-dominated bogs; and forest plantations. Since its inception in 1907, research and education have been the focus of Harvard Forest: the original purpose was to develop a field laboratory for students, a research center in forestry and related disciplines, and a demonstration of practical sustained forestry. Since 1988, Harvard Forest has been a Long-Term Ecological Research site, funded by the National Science Foundation to conduct integrated, long-term studies of forest dynamics.

Network), NEON (National Ecological Observatory↗

NASA NTRS2016

Everglades Ecological Forecasting II: Utilizing NASA Earth Observations to Enhance the Capabilities of Everglades National Park to Monitor & Predict Mangrove Extent to Aid Current Restoration Efforts

Mangroves act as a transition zone between fresh and salt water habitats by filtering and indicating salinity levels along the coast of the Florida Everglades. However, dredging and canals built in the early 1900s depleted the Everglades of much of its freshwater resources. In an attempt to assist in maintaining the health of threatened habitats, efforts have been made within Everglades National Park to rebalance the ecosystem and adhere to sustainably managing mangrove forests. The Everglades Ecological Forecasting II team utilized Google Earth Engine API and satellite imagery from Landsat 5, 7, and 8 to continuously create land-change maps over a 25 year period, and to allow park officials to continue producing maps in the future. In order to make the process replicable for project partners at Everglades National Park, the team was able to conduct a supervised classification approach to display mangrove regions in 1995, 2000, 2005, 2010 and 2015. As freshwater was depleted, mangroves encroached further inland and freshwater marshes declined. The current extent map, along with transition maps helped create forecasting models that show mangrove encroachment further inland in the year 2030 as well. This project highlights the changes to the Everglade habitats in relation to a changing climate and hydrological changes throughout the park.

Kirk, Donnie↗

NASA NTRS2018

Advancing Torpor Inducing Transfer Habitats for Human Stasis to Mars: II - Phase

SpaceWorks Enterprises, Inc. (SEI) has conducted an evaluation of an advanced habitat system designed to transportcrews between the Earth and Mars. This new and innovative habitat concept is capable of placing crew members ininactive, torpor states during transit phases of a deep space mission. This substantially reduces the mass and size ofthe habitat, which ultimately leads to significant reductions in the overall architecture size.Our approach for achieving this is based on extending the current and evolving medical practice of TherapeuticHypothermia (TH) - a proven and effective treatment for various traumatic injuries. TH is a medical treatment thatlowers a patient's body temperature by just 5 to 10 degrees Fahrenheit causing human metabolic rate to decreasesignificantly and the body to enter an unconscious state. This method avoids the intractable challenges often associatedwith cell metabolic cessation through cryogenic freezing and other highly speculative approaches.The initial results obtained from the research and analysis conducted in the Phase I effort warranted further study ofthis concept and technology. The specific objectives of the continued work include:1. Addressing critical medical aspects and risks for inducing torpor via Therapeutic Hypothermia and theapproach for providing nutrition and hydration for the crew during torpor. 2. Focusing on mitigation aspects and technology potential for solving key human spaceflight challenges. 3. Addressing critical engineering aspects of the design that may impact the initial performance and cost resultsobtained in Phase I. 4. Examining the broader extensibility and enabling capabilities of this concept through applicability toadditional exploration missions beyond Mars. 5. Establishing a technology development roadmap, addressing both medical and engineering aspects, thatindicate a logical and scientifically achievable path forward for maturation of this technology.

Stasis↗

NASA NTRSDate not supplied

Baseline Assumptions and Ersatz Waste Streams for Partial Gravity Habitats with Mobile Female and Male Crew

Effective and reliable water management and recovery systems will be required to support human missions beyond the low Earth orbit (LEO) of the International Space Station (ISS). Lunar and Mars surface missions will introduce new challenges to managing water and associated waste streams from mobile crew members who are transiting between up to six living shelters in extreme environmental conditions under a range of gravity conditions. A review of baseline assumptions for the human activities and associated air and water cycles in and between transit vehicle, orbiting station, lander-ascent vehicle, surface habitat, pressurized rover, and suits is conducted. The paper updates ersatz formulations and water flow rates for the main liquid water waste streams of urine, humidity condensate, hygiene, and laundry. Emphasis is placed on the metabolic emissions partitioning between the six vehicles during a design reference mission scenario. Ersatz to represent menses are reviewed.

Dean L Muirhead↗

NASA NTRS2009

Damage Tolerance Testing of a NASA TransHab Derivative Woven Inflatable Module

Edgecombe, John↗

NASA NTRS2008

Damage Tolerance Testing of a NASA TransHab Derivative Woven Inflatable Module

Current options for Lunar habitat architecture include inflatable habitats and airlocks. Inflatable structures can have mass and volume advantages over conventional structures. Inflatable structures are perceived to carry additional risk because they are at a lower Technical Readiness Level (TRL) than conventional metallic structures. One of the risks associated with inflatable structures is understanding the tolerance to component damage and the resulting behavior of the system after the damage is introduced. The Damage Tolerance Test (DTT) is designed to study the structural integrity of an expandable structure during and subsequent to induced damage. The TransHab Project developed an experimental inflatable module developed at Johnson Space Center in the 1990's. The TransHab design was originally envisioned for use in Mars Transits but was also studied as a potential habitat for the International Space Station (ISS). The design of the TransHab module was based on a woven design using an Aramid fabric. Testing of this design demonstrated a high level of predictability and repeatability and good correlation with analytical predictions of stresses and deflections. Based on JSC's experience with the design and analysis of woven inflatable structures, the Damage Tolerance Test article was designed and fabricated using a woven design. The Damage Tolerance Test Article consists of a load bearing restraint layer, a bladder or gas barrier, and a structural metallic core. The test article restraint layer is fabricated from one inch wide Kevlar webbing that is woven in a basket weave pattern. Underneath the structural restraint layer is the bladder or gas barrier. For this test the bladder was required to maintain pressure for testing only and was not representative of a flight design. The bladder and structural restraint layer attach to the structural core of the module at steel bulkheads at each end. The two bulkheads are separated by a 10 foot center tube which provides the structural support for the module when in a non-inflated state as well as resists a portion of the axial load when pressurized. The longitudinal members of the structural restraint layer are attached to the bulkheads using a series of clevises that are bolted to the bulkheads. Strain gages are placed on the clevises that can measure change in load when the structural restraint is inflated. The test module is 88 inches in diameter and 120 inches in height. The objectives of the DTT are to (1) verify the structural integrity of the assembled and pressurized structure when a section of the structural restraint layer is cut by a foreign object, and (2) verify the load distribution of the structural restraint layer during pressurization, before and after the structural restraint layer is severed. For this test, a longitudinal structural restraint strap will be severed using a linear shape charge. The linear shape charge was designed specifically for this application to cut only a single longitudinal strap, while not damaging the bladder. An array of strain gages were located at the bulkhead mounted clevises where the longitudinal restraint layer straps are attached. The DTT article was inflated to 45 psig, 25% of the ultimate design pressure, and one of the one-inch wide longitudinal structural members was severed. Strain gage measurements of loading in an array of longitudinal straps were taken throughout pressurization of the module to 45 psig, before firing of the linear shape charge, and after firing of the shape charge and separation of the strap. During testing not only were the original objectives met but better than expected results occurred. This paper will discuss space inflatable structures, damage tolerance analysis, test results, and applicability to the Lunar architecture.

Edgecombe, John↗