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All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Design of a Jettison System For Space Transit Vehicles

Many options to re-use waste are currently being developed by NASA. These include combustion, compaction, torrefaction, and converting waste materials to an easily stored base polymer for future use. Human exploration missions require large amounts of supplies such as food, clothing and spare parts. A many-month journey to Mars will result in the generation of a substantial amount of problematic waste products. It is thought that this waste must be discarded to enable a Mars transit mission. The most cost-effective, reliable, and safest method to address this problem may be to simply jettison these materials from the spacecraft. The ability to jettison requires a multi-component integrated system design. Major components include a launcher, airlocks, trash bags, and tracking system. Depending upon mission requirements, a jettison dedicated airlock may be necessary. In other cases, the crew airlock might be all that’s needed. Examples of what to jettison include food waste, fecal containers, broken equipment, foam, expendables, hygiene products, health items, wipes, and clothing. The most important design factor is always crew safety. Other features to consider are loss of air due to the inefficiencies of vacuum pumps in the airlock, outgassing from the bags, and liquids condensing on the airlock that result in unwanted coatings. The launching system design must consider many different features: while in planetary orbit, a minimum exit velocity is necessary so the jettisoned material will not complete an orbit only to return and strike the ship. Also, for planetary protection issues, enabling waste to be sent to distant non-critical locations is highly desirable. When the space craft is in planetary transit to say, Mars, the jettison exit velocity should be low if the material is not released along the direction of travel. This is to minimize trajectory perturbations due to jettison-imposed torque on the spacecraft. Design considerations for the launcher include exit velocity, power consumption, volume and mass of material jettisoned, and frequency of jettison. Finally, the launcher must be able to handle many different types and shapes of waste products. This paper will discuss these design issues and give guidance to a pathway forward.

Steve Sepka↗
NASA NTRS2022

Real-time rapid leakage estimation for deep space habitats using exponentially-weighted adaptively-refined search

The recent accelerated growth in space-related research and development activities makes the near-term need for long-term extraterrestrial habitats evident. Such habitats must operate under continuous disruptive conditions arising from extreme environments like meteoroid impacts, extreme temperature fluctuations, galactic cosmic rays, destructive dust, and seismic events. Loss of air or atmospheric leakage from a habitat poses safety challenges that demand proper attention. Such leakage may arise from micro-meteoroid impacts, crack growth, bolt/rivet loosening, and seal deterioration. In this paper, leakage estimation in deep space habitats is posed as an inverse problem. A forward pressure-based dynamical model is formulated for atmospheric leakage. Experiments are performed on a small-scaled pressure chamber where different leakage scenarios are emulated and corresponding pressure values are measured. An exponentially-weighted adaptively-refined search (EWARS) algorithm is developed and validated for the inverse problem of real-time leakage estimation. It is demonstrated that the proposed methodology can achieve real-time estimation and tracking of constant and variable leaks with accuracy.

Deep space habitats↗
NASA NTRSDate not supplied

Textual and Network Analysis of Part 107 Waivers

Context: The management of hazards in sUAS operations is not as well defined as today's commercial operations despite sUAS widespread use. Part 107 waived operations' provisions, which manage hazards for higher risk operations that require approval, can offer insight to organizations establishing UAS Programs in managing their own operation hazards. Aim: We seek to understand how the FAA Part 107 waived operations manage hazards. Method: We used the constant comparative method to identify hazard mitigation textual categories from provisions and use networks to assess the dispersion of provisions and the identified categories across issued waivers. Results: Eight mitigation categories and twenty-four sub-categories were identified. Most provisions present in waivers are mostly reused in one waiver. Conclusion: While there is a broad range of provisions to control for hazard mitigations in the Part 107 issued waivers analyzed regulations, they require case-by-case modifications.

Urban Air Mobility↗
NASA NTRSDate not supplied

Textual and Network Analysis of Title 14 CFR Part107 Waivers

Context: The management of hazards in small unmanned aircraft systems (sUAS) operations is not as well defined as today's commercial operations despite sUAS widespread use. FAA Title 14 Code of Federal Regulations (CFR) Part 107 waived operations' provisions, which manage hazards for higher risk operations that require approval, can offer insight to organizations establishing UAS Programs in managing their own operation hazards. Aim: We seek to understand how the Title 14 CFR Part 107 waived operations manage hazards. Method: We used the constant comparative method to identify hazard mitigation textual categories from provisions and use networks to assess the dispersion of provisions and the identified categories across issued waivers. Results: Eight mitigation categories and twenty-four sub-categories were identified. Most provisions present in waivers are mostly reused in one waiver. Conclusion: While there is a broad range of provisions to control for hazard mitigations in the Title 14 CFR Part 107 issued waivers analyzed regulations, they require case-by-case modifications.

Urban Air Mobility↗
NASA NTRS1994

The meteorological monitoring system for the Kennedy Space Center/Cape Canaveral Air Station

The Kennedy Space Center (KSC) and Cape Canaveral Air Station (CCAS) are involved in many weather-sensitive operations. Manned and unmanned vehicle launches, which occur several times each year, are obvious example of operations whose success and safety are dependent upon favorable meteorological conditions. Other operations involving NASA, Air Force, and contractor personnel, including daily operations to maintain facilities, refurbish launch structures, prepare vehicles for launch, and handle hazardous materials, are less publicized but are no less weather-sensitive. The Meteorological Monitoring System (MMS) is a computer network which acquires, processes, disseminates, and monitors near real-time and forecast meteorological information to assist operational personnel and weather forecasters with the task of minimizing the risk to personnel, materials, and the surrounding population. CLIPS has been integrated into the MMS to provide quality control analysis and data monitoring. This paper describes aspects of the MMS relevant to CLIPS including requirements, actual implementation details, and results of performance testing.

Dianic, Allan V.↗
NASA NTRS1996

Aeronautics and Space Report of the President: Fiscal Year 1996 Activities

Topics considered include: (1) Space launch activities: space shuttle missions; expendable launch vehicles. (2) Space science: astronomy and space physics; solar system exploration. (3) Space flight and technology: life and microgravity sciences; space shuttle technology; reuseable launch vehicles; international space station; energy; safety and mission assurance; commercial development and regulation of space; surveillance. (4) Space communications: communications satellites; space network; ground networks; mission control and data systems. (5) Aeronautical activities: technology developments; air traffic control and navigation; weather-related aeronautical activities; flight safety and security; aviation medicine and human factors. (6) Studies of the planet earth: terrestrial studies and applications: atmospheric studies: oceanographic studies; international aeronautical and space activities; and appendices.

Source record↗
NASA NTRS2015

Simulation and Analysis of Technology and Operational Procedures to Reduce the Combined Effects of Emissions and Contrails

The development and evaluation of concepts and technology to support future air traffic management systems require a hierarchy of models ranging from real-time simulations to extensive field evaluations. Air traffic simulation models such as Airspace Concept Evaluation System, Center Tracon Automation System, Future Air traffic management Concept Evaluation Tool and others are used to design air traffic systems balancing the conflicting objectives of maximizing safety, meeting future demands for airports and airspace and increase efficiency of traffic flows in the presence of uncertain weather. The impact of aviation emissions and contrails on climate imposes another constraint on the design of aircraft and aviation operations. The understanding of the complex interaction between physical climate system, the carbon and other greenhouse gas emissions and aviation activity can be improved by the development of integrated assessment models that include emission and climate models together with air traffic simulations. The modeling of aircraft emissions and their interaction with each other to change the concentration levels of different gasses in the atmosphere and the resulting impact of the radiative forcing on the equilibrium of the Earth's atmosphere is complex and requires the use of coupled atmosphere-ocean general circulation models together with three-dimensional models of carbon cycle and chemistry of other non-CO2 greenhouse gases. These models are computationally intensive and unsuitable for studies involving the generation of multiple scenarios. Simple emission and climate models, based on the input-output relations of linear systems, capture the fundamental emission to climate impact behavior by careful selection of key variables and their dynamics. The impact of various greenhouse gases depends on the total concentration, effect per unit change in atmospheric concentration and the spatial distribution of the gas. All these quantities are influenced by the lifetime of the gas. The impact of a greenhouse gas depends on the interval of assessment, which may vary from a few decades to a few centuries. Climate metrics are aimed at providing a common scale to compare different greenhouse gases. If the metrics are to be used as a tool in developing and evaluating aviation operations, they should be transparent and easy to apply. Global Warming Potential and Aggregate Global Temperature Potential are some of the commonly used metrics. This paper integrates a national-level air traffic simulation and optimization capability with simple climate models and carbon cycle models, and climate metrics to assess the impact of aviation on climate. The capability brings together metrics, which are useful in aviation operations together with metrics used in climate studies. The capability can be used to make trade-offs between extra fuel cost and reduction in climate impact. There is considerable uncertainty in our understanding of the radiative forcing associated with emissions and contrails. The parameters in the simulation can be used to evaluate the effect of various uncertainties in emission models and contrails. It can also be used to evaluate the impact of different decision horizons. Alternatively, the optimization results from the simulation can be used as inputs to other tools that monetize global climate impacts like the FAA's Aviation Environmental Portfolio Management Tool for Impacts.

impact of aviation on the environment↗
NASA NTRS2017

ATD-1 Avionics Phase 2 Flight Test: Flight Test Operations and Saftey Report (FTOSR)

The Air Traffic Management Technology Demonstration-1 (ATD-1) is a major applied research and development activity of NASA's Airspace Operations and Safety Program (AOSP). The demonstration is the first of an envisioned series of Air Traffic Management (ATM) Technology Demonstration sub-projects that will demonstrate innovative NASA technologies that have attained a sufficient level of maturity to merit more in-depth research and evaluation at the system level in relevant environments.

Boyle, Dan↗
NASA NTRS2021

Decentralized Control Synthesis for Air Traffic Management in Urban Air Mobility

Urban air mobility (UAM) refers to air transportation services within an urban area, often in an on-demand fashion. We study air traffic management (ATM) for vehicles in a UAM fleet, while guaranteeing system safety requirements such as traffic separation. Existing ATM methods for unmanned aerial systems, such as UAS traffic management, utilize alternative approaches which do not provide strict safety guarantees. No established infrastructure exists for providing ATM at scale for UAM. We provide a decentralized, hierarchical approach for UAM ATM that allows for scalability to high traffic densities as well as providing theoretical guarantees of correctness with respect to user-provided safety specifications. Our main contributions are two-fold. First, we propose a novel UAM ATM architecture that divides the control authority between vertihubs that are each in charge of all UAM vehicles in their local airspace. Each vertihub also contains a number of vertiports that are in charge of UAM vehicle takeoffs and landings. The resulting architecture is decentralized and hierarchical, which not only enables scalability, but also robustness in the event of any individual vertihub or vertiport no longer being operational. Second, we provide a contract-based correct-by-construction reactive synthesis approach that provably guarantees safety properties with respect to user-provided specifications in linear temporal logic. We demonstrate the approach on large-volume UAM air traffic data.

Urban Air Mobility↗
NASA NTRS2020

Solid-state Architecture Batteries for Enhanced Rechargeability and Safety (SABERS)

All-electric vertical take-off and landing vehicles (eVTOL) for urban air mobility (UAM) concepts face numerous challenging technical barriers before their introduction into the consumer marketplace. The most challenging of these technical barriers to overcome is developing an energy storage system capable of meeting the rigorous aerospace safety and performance criteria. The performance metrics for eVTOL craft, such as specific energy and cycle life, are at least 2 times greater than those of electric automobiles. Furthermore, safety is essential for operation of commercial electric aerovehicles. Preliminary systems level analysis studies have indicated that there are five key properties which must be optimized for successful implementation of battery systems. Those five key criteria are safety, energy density, power, packaging design and scalability. Current state-of-the-art (SOA) lithium-ion batteries meet or exceed the requirements for electric aviation in the areas of power and scalability, yet are insufficient in the key performance criteria of energy, safety and packaging design. The SABERS concept proposes a battery that meets all five key performance criteria through the development of a solid-state architecture cell design utilizing high energy density and power density sulfur-selenium cathode with a lithium metal anode. Data will be presented demonstrating high performing sulfur - selenium cathode that offers a balanced energy to power density ratio, which can be tailored to the specific application by altering the stoichiometric ratios of sulfur to selenium. This cathode is being developed by implementing NASA patented holey graphene technology as a highly conductive, ultra-lightweight electrode scaffold. Novel processing methods allow developing solid-state electrolyte that is a safe, non-flammable replacement to the highly flammable liquid organic electrolytes currently used in SOA lithium-ion batteries. The all solid-state lithium-sulfur-selenium cell design enables the implementation of a bipolar stack configuration, which has the advantages of reducing overall cell weight, reducing the amount of interfaced connections for the cell, and minimizing cooling requirements for the battery. In particular, the solid-state design allows for a serial stacking configuration to enable dense packaging of the cells within the bipolar stack. Lastly, optimization of battery components occurs through a robust and rigorous combination of various computational modeling techniques covering multiple length scales. The expected result will be a solid-state battery with operational temperatures from 0 °C to 150 °C which provides the required energy density, discharge rate, and inherent safety to meet strict aerospace performance criteria.

solid state batteries↗
DOE OSTI2024

Enhancing thermal resilience of US residential homes in hot humid climates during extreme temperature events

Increasing occurrences of extreme weather events such as winter storms and heat waves due to climate change pose enormous safety and health-related risks to people, particularly in economically disadvantaged communities. In this study, we investigate some of the most promising retrofittable and weatherization methods to keep the living zone of residential buildings within an acceptable safety level. We use hours of safety as the resilience metric, which is defined as the time taken by the building's indoor environment to reach a safety threshold temperature. We first identify various passive measures, such as adding extra insulation, improving air sealing, and integrating phase-change materials, which can operate without any external power during winter-storm and heat-wave events. We then employ a whole-building simulation tool to examine the impact of various combinations of retrofit measures and conduct a parametric study to determine the optimal solutions.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
NASA NTRS2004

Formal Verification of a Conflict Resolution and Recovery Algorithm

New air traffic management concepts distribute the duty of traffic separation among system participants. As a consequence, these concepts have a greater dependency and rely heavily on on-board software and hardware systems. One example of a new on-board capability in a distributed air traffic management system is air traffic conflict detection and resolution (CD&R). Traditional methods for safety assessment such as human-in-the-loop simulations, testing, and flight experiments may not be sufficient for this highly distributed system as the set of possible scenarios is too large to have a reasonable coverage. This paper proposes a new method for the safety assessment of avionics systems that makes use of formal methods to drive the development of critical systems. As a case study of this approach, the mechanical veri.cation of an algorithm for air traffic conflict resolution and recovery called RR3D is presented. The RR3D algorithm uses a geometric optimization technique to provide a choice of resolution and recovery maneuvers. If the aircraft adheres to these maneuvers, they will bring the aircraft out of conflict and the aircraft will follow a conflict-free path to its original destination. Veri.cation of RR3D is carried out using the Prototype Verification System (PVS).

Maddalon, Jeffrey↗
DOE OSTI2024

A Sulfide‐Based Solid Electrolyte With High Humid Air Tolerance for Long Lifespan All‐Solid‐State Sodium Batteries

Abstract Sulfide‐based superionic conductors present great promise to achieve high energy density and safety for all‐solid‐state sodium batteries (ASSSBs). However, the poor electrolyte/electrode interface compatibility and humid air stability seriously hinder their deployment in ASSSBs. Herein, a series of high‐performance Na 3‐□ Sb 1‐4x (SnWCaTi) x S 4 sulfide‐based solid electrolytes (SSEs) are reported by coupling the vacancy effect with configurational entropy, which displays an excellent interface stability against sodium metal and an extraordinary tolerance toward the moist atmosphere, even for water. The optimized electrolyte effectively inhibits the detrimental mixed ion‐electron conducting interphase formation, achieving the ultra‐stable operation of Na–Na symmetric cell up to 1000 h. Furthermore, the Na + diffusion kinetics is obviously enhanced by increasing the Na sites local anisotropy and Na vacancies. Eventually, the assembled TiS 2 //Na 5 Sn ASSSBs deliver a remarkable reversible capacity of 211.6 mAh g −1 at 0.5C with a long‐term cycling performance of 450 cycles at room temperature. More importantly, it achieves a steady running up to 100 cycles at 1C even if this electrolyte is placed in the air with a dew temperature of 13.8 °C for 30 min, the highest values in the state‐of‐the‐art sulfide‐based ASSSBs. The well‐designed SSEs open a new avenue for realizing the advanced and powerful ASSSBs.

Guo, Yayu↗
DOE OSTI2020

Two-phase operation of a Terry steam turbine using air and water mixtures as working fluids

Terry steam turbines are employed in the safety systems of many nuclear Boiling Water Reactors to drive pumps and provide cooling water to the nuclear reactor core. While the turbine efficiency is low, the more important feature is high reliability under off-normal conditions. An important aspect of reliability is the ability to function with two-phase steam-water injection into the turbine, as most likely occurred in the Fukushima Dai-ichi nuclear accidents. This study investigates the characteristics of a Terry turbine during air-water injection with gas mass fractions ranging from 1 (dry gas) to 0.05 (wet gas), to better understand the Terry turbine’s true operational capabilities and provide justification for extended Terry turbine use for reactor safety. Other parameters investigated are the inlet pressure, the exhaust backpressure and the turbine’s rotational speed. The turbine performance is presented in terms of dynamometer loading and pump performance change as functions of the gas mass fraction.

42 ENGINEERING↗
DOE OSTI2024

Comfort and Safety Metrics to Evaluate Customer Centric Resilience Enhancement Strategies

As the coincident events of extreme weather and major power outages continue to rise there is an increased need to implement resilience solutions. Many of these solutions are customer-centric, requiring the flexibility of demand, and many of the standard economic evaluations of these solutions do not include the benefits of resilience that are not easily quantified and monetized. Indoor air temperature has a large impact on the comfort and safety of building occupants during an extreme weather event. This work proposes metrics that can be used to compare the performance of resilience solutions in the context of comfort and safety.

Cost benefit analysis, Demand Side Management, Pow↗
NASA NTRS2012

Integration of Linear Dynamic Emission and Climate Models with Air Traffic Simulations

Future air traffic management systems are required to balance the conflicting objectives of maximizing safety and efficiency of traffic flows while minimizing the climate impact of aviation emissions and contrails. Integrating emission and climate models together with air traffic simulations improve the understanding of the complex interaction between the physical climate system, carbon and other greenhouse gas emissions and aviation activity. This paper integrates a national-level air traffic simulation and optimization capability with simple climate models and carbon cycle models, and climate metrics to assess the impact of aviation on climate. The capability can be used to make trade-offs between extra fuel cost and reduction in global surface temperature change. The parameters in the simulation can be used to evaluate the effect of various uncertainties in emission models and contrails and the impact of different decision horizons. Alternatively, the optimization results from the simulation can be used as inputs to other tools that monetize global climate impacts like the FAA s Aviation Environmental Portfolio Management Tool for Impacts.

Sridhar, Banavar↗
NASA NTRS1992

The role of Environmental Health System air quality monitors in Space Station Contingency Operations

This paper describes the Space Station Freedom (SSF) Environmental Health System's air-quality monitoring strategy and instrumentation. A two-tier system has been developed, consisting of first-alert instruments that warn the crew of airborne contamination and a volatile organic analyzer that can identify volatile organic contaminants in near-real time. The strategy for air quality monitoring on SSF is designed to provide early detection so that the contamination can be confined to one module and so that crew health and safety can be protected throughout the contingency event. The use of air-quality monitors in fixed and portable modes will be presented as a means of following the progress of decontamination efforts and ensuring acceptable air quality in a module after an incident. The technology of each instrument will be reviewed briefly; the main focus of this paper, however, will be the use of air-quality monitors before, during, and after contingency incidents.

Limero, Thomas F.↗
NASA NTRS2008

Structural Design and Analysis of the Upper Pressure Shell Section of a Composite Crew Module

This paper presents the results of the structural design and analysis of the upper pressure shell section of a carbon composite demonstration structure for the Composite Crew Module (CCM) Project. The project is managed by the NASA Engineering and Safety Center with participants from eight NASA Centers, the Air Force Research Laboratory, and multiple aerospace contractors including ATK/Swales, Northrop Grumman, Lockheed Martin, Collier Research Corporation, Genesis Engineering, and Janicki Industries. The paper discusses details of the upper pressure shell section design of the CCM and presents the structural analysis results using the HyperSizer structural sizing software and the MSC Nastran finite element analysis software. The HyperSizer results showed that the controlling load case driving most of the sizing in the upper pressure shell section was the internal pressure load case. The regions around the cutouts were controlled by internal pressure and the main parachute load cases. The global finite element analysis results showed that the majority of the elements of the CCM had a positive margin of safety with the exception of a few hot spots around the cutouts. These hot spots are currently being investigated with a more detailed analysis. Local finite element models of the Low Impact Docking System (LIDS) interface ring and the forward bay gussets with greater mesh fidelity were created for local sizing and analysis. The sizing of the LIDS interface ring was driven by the drogue parachute loads, Trans-Lunar Insertion (TLI) loads, and internal pressure. The drogue parachute loads controlled the sizing of the gusset cap on the drogue gusset and TLI loads controlled the sizing of the other five gusset caps. The main parachute loads controlled the sizing of the lower ends of the gusset caps on the main parachute fittings. The results showed that the gusset web/pressure shell and gusset web/gusset cap interfaces bonded using Pi-preform joints had local hot spots in the Pi-preform termination regions. These regions require a detailed three-dimensional analysis, which is currently being performed, to accurately address the load distribution near the Pi-preform termination in the upper and lower gusset caps.

Sleight, David W.↗