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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
NASA NTRS2019

Field Evaluations of Sampling, Interviewing, and Flight Tracking of NASA's Low Boom Flight Demonstrator Aircraft

The first year’s effort identified sampling and interviewing as the principal risks to assessment of prompt reactions to overflights producing low-amplitude sonic booms. It also 1) established the utility of geo-information system-based route planning for LBFD flight missions, 2) developed and demonstrated a prototype of a geographically-distributed, Internet-enabled instrumentation system capable of wide-area tracking of LBFD aircraft in near-real time. The latter system permits synchronizing the conduct of interviews in multiple overflown communities with arrival times of shock waves at interviewing sites; and of measuring, archiving, and processing their acoustic signatures. Means were also recommended for constructing representative, telephone-based samples of eligible respondents living in households within carpet boom corridors adjacent to LBFD flight tracks, and for conducting interviews with cross-sectional (independent) samples of such respondents about their prompt reactions to exposure to low-amplitude sonic booms. A detailed study design was prepared and accepted by NASA for a set of single-contact attempt telephone interviews with a nationally representative sample of households. The study design focused on testing automated and live agent interview completion rates obtainable without callbacks. A minimal (two monitoring station) version of the aircraft tracking system was built and installed near a civil airport in a successful demonstration of the system’s ability to detect and track aircraft movements. The field exercise also demonstrated the ability of the system to capture the acoustic emissions of departing aircraft, and to serve aircraft position and sound level information to remote, geographically-distributed analysts in near-real time. Upon approval of OMB and IRB of the detailed study plan, a stratified, nationally representative sample of landline and wireless telephone-subscribing households was constructed. A total of 12,734 telephone interview contact attempts of the sort required by a straightforward cross-sectional study design were then made. These contact attempts demonstrated the impracticality of conducting a time-critical, cross-sectional study of prompt community response to low-amplitude sonic booms by means of “independent” (single contact attempt per respondent for each LBFD flight mission) telephone samples of respondents. The observed interview completion rates for these single telephone contact attempts were so low (~ 1% to 3% for automated and live agent interviews, respectively) that: 1) the representativeness of collected opinions would be susceptible to intuitive challenge as inadequate, even absent conclusive evidence of non-representativeness. Refuting challenges to representativeness would have to demonstrate that the composition of the actual sample did not differ from that of the target population, a task that is tantamount to proving a negative; 2) the information required to refute allegations of non-representativeness would require a questionnaire considerably lengthier than that required simply to determine the prevalence of boom-induced startle and annoyance. Such a questionnaire would have to inquire about potentially sensitive and intrusive matters, including respondents’ age, gender, education, employment, home ownership, income, ethnicity, family size, and other demographic factors; and 3) unreasonable numbers of attempts would be required to re-contact households with unsuccessful initial contact attempts, given the limited time available for doing so. For example, if about 500 completed interviews were desired in a supersonically overflown community, approximately 50,000 automated interview attempts would have to be made within ten to fifteen minutes of each LBFD overflight. Such large numbers of contact attempts could well exceed the numbers of households available for interview in areas of similar boom exposure levels in some communities near LBFD flight tracks. Such large numbers of interviews could be cost-effectively undertaken only by means of automated (i.e., outgoing interactive voice response) interviewing, a data collection method ill-suited for complex and sensitive questionnaire items. The infeasibility of independent sampling for evaluating prompt responses to LBFD overflights in a cross-sectional study is due in large part to simple non-response: that is, potential respondents – particularly those contacted on wireless telephones – refusing to answer calls with unfamiliar caller IDs. It is also due in part, however, to 1) the lack of time to attempt to contact the same respondent more than once within a few minutes after the arrival of a shock wave at the respondent’s location; and 2) the need to place calls during weekday/daytime hours, when response rates are notably lower than during evenings and weekends. Despite the poor interview completion rates achieved under the above constraints, cross sectional assessments of delayed reactions to LBFD overflights could still be feasible, if multiple attempts could be made to contact respondents during evening and weekend time periods, over extended time periods. Detailed plans for a longitudinal (panel) sample were developed as an alternative to a cross sectional sample design.

Fidell, Sanford↗
NASA NTRSDate not supplied

Spacecraft-Initiated Scheduling of Commercial Communications Services

We propose a software framework enabling a spacecraft in Earth orbit to schedule its own access to space communications services via ground stations and relay satellites. All operations are automated, without a human in the loop, allowing for highly responsive service to meet time-varying needs. We describe a modular software architecture allowing the framework to interface with the scheduling systems of several providers - both government and commercial. Specifically, we present the results of an experiment with Amazon Web Services (AWS) Ground Station, an operational commercial service provider. Proposed software executed scheduling of a ground station antenna with minimal lead time (less than 20 minutes before the start of a pass). During the contact AWS cloud infrastructure was used to demodulate, process, and distribute data products from an orbiting satellite. We believe this work demonstrates the framework's ability to interface with additional providers and potential to integrate more complex decision-making in the future to schedule optimal contacts.

Scheduling↗
NASA NTRS2013

Controlled, Site-Specific Functionalization of Carbon Nanotubes with Diazonium Salts

This work uses existing technologies to prepare a crossbar architecture of nano tubes, wherein one nanotube is fixed to a substrate, and a second nanotube is suspended a finite distance above. Both nano tubes can be individually addressed electrically. Application of opposite potentials to the two tubes causes the top tube to deform and to essentially come into contact with the lower tube. Contact here refers not to actual, physical contact, but rather within an infinitesimally small distance referred to as van der Walls contact, in which the entities may influence each other on a molecular and electronic scale. First, the top tube is physically deformed, leading to a potentially higher chemical reactivity at the point of deformation, based on current understanding of the effects of curvature strain on reactivity. This feature would allow selective functionalization at the junction via reaction with diazonium salts. Secondly, higher potential is achieved at the point of "cross" between the tubes. In a pending patent application, a method is claimed for directed self-assembly of molecular components onto the surface of metal or conductive materials by application of potential to the metal or conductive surface. In another pending patent application, a method is claimed for attaching molecules to the surface of nanotubes via the use of reactive diazonium salts. In the present invention, the directed functionalization of the crossed-nanotube junctions by applying a potential to the ends of the nanotubes in the presence of reactive diazonium slats, or other reactive molecular species is claimed. The diazonium salts are directed by the potential existing at the junction to react with the surface of the nanotube, thus placing functional molecular components at the junctions. The crossed nano tubes therefore provide a method of directly addressing the functionalized molecules, which have been shown to function as molecular switches, molecular wires, and in other capacities and uses. Site-specific functionalization may enable the use of nanotubes in molecular electronic applications because device functionality is critical at the cross points.

Tour, James M.↗
NASA NTRS2019

An Analytic Model for Estimating the First Contact Resistance Needed to Avoid Damaging ESD During Spacecraft Docking in GEO

NASA’s Gateway program will involve spacecraft (s/c) docking in the outer radiation belt in order to transfer Gateway elements between s/c for transport to lunar orbit. The charging of these s/c to different potentials prior to docking raises the possibility of a damaging electrostatic discharge (ESD) at the time of first contact between the s/c. A proposed mitigation strategy is for first contact to occur prior to docking through a resistor with resistance R that would lower the potential difference at an optimal rate to a sufficiently low value to prevent ESD damage. The coupling of s/c by a resistor can be modeled by SPIS, but for realistic two s/c models SPIS can take hours to simulate the evolution of the s/c surface charges and potentials to an equilibrium state. Our objective is to develop a simpler model of s/c resistive coupling that runs orders of magnitude faster while providing useful first design estimates of the time variation of the s/c potentials, current through the resistor, and how these vary with R and s/c configuration This configuration is defined by the relative separation and orientation of the s/c, and their solar illumination. The configuration and geometry of the s/c determine their capacitive coupling. The s/c capacitances are computed using Nascap-2K. This poster presents the first version of such a model, and initial tests.

Goodman, Michael L.↗
NASA NTRS2004

Subsurface Stress Fields In Single Crystal (Anisotropic) Contacts

Single crystal superalloy turbine blades used in high pressure turbomachinery are subject to conditions of high temperature, triaxial steady and alternating stresses, fretting stresses in the blade attachment and damper contact locations, and exposure to high-pressure hydrogen. The blades are also subjected to extreme variations in temperature during start-up and shutdown transients. The most prevalent HCF failure modes observed in these blades during operation include crystallographic crack initiation/propagation on octahedral planes, and noncrystallographic initiation with crystallographic growth. Numerous cases of crack initiation and crack propagation at the blade leading edge tip, blade attachment regions, and damper contact locations have been documented. Understanding crack initiation/propagation under mixed-mode loading conditions is critical for establishing a systematic procedure for evaluating HCF life of single crystal turbine blades. This paper presents analytical and numerical techniques for evaluating two and three dimensional subsurface stress fields in anisotropic contacts. The subsurface stress results are required for evaluating contact fatigue life at damper contacts and dovetail attachment regions in single crystal nickel-base superalloy turbine blades. An analytical procedure is , presented, for evaluating the subsurface stresses in the elastic half-space, using a complex potential method outlined by Lekhnitskii. Numerical results are presented for cylindrical and spherical anisotropic contacts, using finite element analysis. Effects of crystal orientation on stress response and fatigue life are examined.

Arakere, Nagaraj K.↗
NASA NTRS2019

An Analytic Model for Estimating the First Contact Resistance Needed to Avoid Damaging ESD During Spacecraft Docking in GEO

NASA’s Gateway program is to involve spacecraft (s/c) docking in the outer radiation belt in order to transfer Gateway elements between s/c for transport to lunar orbit. The charging of these s/c to different potentials prior to docking raises the possibility of a damaging electrostatic discharge (ESD) at the time of first contact between the s/c. A proposed mitigation strategy is for first contact to occur prior to docking through a resistor with resistance R that would lower the potential difference at an optimal rate to a sufficiently low value to prevent a damaging ESD. The coupling of s/c by a resistor can be modeled by SPIS (Spacecraft Plasma Interaction System), but for realistic two s/c models SPIS can take hours to simulate the evolution of the s/c surface charges and potentials to an equilibrium state. Our objective is to develop a simpler model of s/c resistive coupling that runs orders of magnitude faster while providing useful first design estimates of the time variation of the s/c potentials, current through the resistor, and how these vary with R and s/c configuration. This configuration is defined by the relative separation and orientation of the s/c, and their solar illumination. The configuration and geometry of the s/c determine their capacitive coupling. The s/c capacitances are computed using Nascap-2K. This abstract and the associated poster describe the first version of such a model, and initial tests.

Goodman, Michael L.↗
DOE OSTI2026

Investigation Into LiCl-LiF+Li 2 O as a Low Temperature Electrolyte in Direct Electrolytic Reduction of UO 2

Direct electrolytic reduction (DER) of UO 2 in a binary LiCl-Li2O (1–3 wt%) at 650 °C has been widely reported. The process temperature can be reduced to 550 °C in theory by using a near eutectic ternary LiCl-LiF+Li 2O (∼2 wt%) electrolyte, which will result in substantial reduction in rate of salt vaporization. The feasibility of using the ternary electrolyte for the process was tested via material compatibility testing, electrochemical polarization testing, and controlled potential or current DER experiments. MgO, Pt, and 625 nickel samples were each contacted with the ternary salt for 168 h. Negligible changes to dimensions and mass of the samples were measured, and concentrations of corrosion products in the salt were 102 ppm or less. O2−oxidation was observed to occur at a lower potential than Cl-or F-on a Pt anode. DER of UO2was performed in six trials. Process variables included type of reference electrode, electrochemical control method, type of cathode basket, and electrolyte composition. UO 2conversion ranged from 28.2 to 99.9 % , and current efficiency ranged from 38 to 52%. Overall, results indicate that the use of the ternary salt is feasible for DER.

36 MATERIALS SCIENCE↗
DOE OSTI2024

A New High-Impedance-Fault Detection Method to Prevent Power-Line-Induced Wildfires

High Impedance Faults (HIFs) occur when energized power lines come into contact with high impedance ground surfaces, such as tree branches and grassland. HIFs have the potential to cause arcing, leading to vegetation ignition and the initiation of wildfires. The challenge in detecting HIFs comes from the high impedance of the partially conductive materials in contact with the power lines. They create a fault current of low magnitude and traditional protective devices struggle to detect such faults. This paper proposes a novel HIF detection algorithm based upon the analyzed arcing signatures associated with HIFs. The algorithm is evaluated using the Australian Public Bushfire Safety Program (PBSP) dataset. For comparative analysis, a state-of-the-art commercial HIF detection product is also evaluated using the same dataset. The proposed algorithm demonstrates higher detection accuracy over the commercial products with fewer false flags and undetected faults.

grasslands↗
NASA NTRS1989

Plasma contacting - An enabling technology

An experimental study of plasma contacting with an emphasis on the electron collection mode of this process is described. Results illustrating variations in plasma property profiles and potential differences that develop at hollow cathode plasma contactors are presented. A model of the electron collection plasma contacting process that is consistent with experimentally measured results is reviewed. The shortcomings of laboratory results as direct predictors of contactor performance in space and their usefulness in validating numerical models of the contacting process, that can be used to predict such performance, are discussed.

Williams, John D.↗
DOE OSTI2024

Anion-derived contact ion pairing as a unifying principle for electrolyte design

Enabling new electrochemical technologies requires systems that can operate under ever-more demanding conditions, and progress in energy storage applications reveals tantalizing opportunities to reimagine electrolyte design for performance at extreme potentials. Here, a common thread among these innovations is the formation of significant populations of contact ion pairs (CIPs) in the electrolyte, regardless of the specific cation chemistry or solvent system. The examples summarized in this review suggest that a set of general electrolyte design rules likely exists, where the purposeful selection of anion chemistry can yield CIP structures with tunable control over reaction thermodynamics, kinetics, and interphase chemistry. Identifying the relevant descriptors for high-performance, anion-derived CIP structures can be achieved utilizing a combined experimental and computational approach, aided by machine learning and artificial intelligence, to more rapidly survey the vast combinatorial space available and to enable a new generation of electrolytes for decarbonized electrochemical processes at scale.

electrochemistry↗
DOE OSTI2026

Nonlinear thermodynamic computing out of equilibrium

We present the design for a thermodynamic computer that can perform arbitrary nonlinear calculations in or out of equilibrium. Simple thermodynamic circuits, fluctuating degrees of freedom in contact with a thermal bath and confined by a quartic potential, display an activity that is a nonlinear function of their input. Such circuits can therefore be regarded as thermodynamic neurons, and can serve as the building blocks of networked structures that act as thermodynamic neural networks, universal function approximators whose operation is powered by thermal fluctuations. We simulate a digital model of a thermodynamic neural network, and show that its parameters can be adjusted by genetic algorithm to perform nonlinear calculations at specified observation times, regardless of whether the system has attained thermal equilibrium. This work expands the field of thermodynamic computing beyond the regime of thermal equilibrium, enabling fully nonlinear computations, analogous to those performed by classical neural networks, at specified observation times.

Whitelam, Stephen [Lawrence Berkeley National Labo↗
NASA NTRS1993

Space exploration initiative candidate nuclear propulsion test facilities

One-page descriptions for approximately 200 existing government, university, and industry facilities which may be available in the future to support SEI nuclear propulsion technology development and test program requirements are provided. To facilitate use of the information, the candidate facilities are listed both by location (Index L) and by Facility Type (Index FT). The included one-page descriptions provide a brief narrative description of facility capability, suggest potential uses for each facility, and designate a point of contact for additional information that may be needed in the future. The Nuclear Propulsion Office at NASA Lewis presently plans to maintain, expand, and update this information periodically for use by NASA, DOE, and DOD personnel involved in planning various phases of the SEI Nuclear Propulsion Project.

Baldwin, Darrell↗
NASA NTRS2002

Charge Generation and Propagation in Igneous Rocks

Various electrical phenomena have been reported prior to or concurrent with earthquakes such as resistivity changes, ground potentials, electromagnetic (EM), and luminous signals. Doubts have been raised as to whether some of these phenomena are real and indeed precursory. One of the reasons for uncertainty is that, despite decades of intense work, there is still no physically coherent model. Using low- to medium-velocity impacts to measure electrical signals with microsecond time resolution, it has now been observed that when dry gabbro and diorite cores are impacted at relatively low velocities, approximately 100 m/s, highly mobile charge carriers are generated in a small volume near the impact point. They spread through the rocks, causing electric potentials exceeding +400 mV, EM, and light emission. As the charge cloud spreads, the rock becomes momentarily conductive. When a dry granite block is impacted at higher velocity, approximately 1.5 km/s, the propagation of the P and S waves is registered through the transient piezoelectric response of quartz. After the sound waves have passed, the surface of the granite block becomes positively charged, suggesting the same charge carriers as observed during the low-velocity impact experiments, expanding from within the bulk. During the next 2-3 ms the surface potential oscillates, indicating pulses of electrons injected from ground and contact electrodes. The observations are consistent with positive holes, e.g., defect electrons in the O(2-) sublattice, traveling via the O 2p-dominated valence band of the silicate minerals. Before activation, the positive holes lay dormant in the form of electrically inactive positive hole pairs (PHP), chemically equivalent to peroxy links, O3X/OO\XO3, with X=Si(4+), Al(3+), etc. PHPs are introduced into the minerals by way of hydroxyl,O3X-OH, which all nominally anhydrous minerals incorporate when crystallizing in H2O-laden environments. The fact that positive holes can be activated by low-energy impacts, and their attendant sound waves, suggests that they can also be activated by microfracturing. Depending on where in the stressed rock volume the charge carriers are activated, they will form rapidly moving or fluctuating charge clouds that may account for earthquake-related electrical signals and EM emission. Wherever such charge clouds intersect the surface, high fields are expected, causing electric discharges and earthquake lights.

Freund, Friedemann↗
NASA NTRS2008

LOCAD-PTS: Operation of a New System for Microbial Monitoring Aboard the International Space Station (ISS)

Microorganisms within the space stations Salyut, Mir and the International Space Station (ISS), have traditionally been monitored with culture-based techniques. These techniques involve growing environmental samples (cabin water, air or surfaces) on agar-type media for several days, followed by visualization of resulting colonies; and return of samples to Earth for ground-based analysis. This approach has provided a wealth of useful data and enhanced our understanding of the microbial ecology within space stations. However, the approach is also limited by the following: i) More than 95% microorganisms in the environment cannot grow on conventional growth media; ii) Significant time lags occur between onboard sampling and colony visualization (3-5 days) and ground-based analysis (as long as several months); iii) Colonies are often difficult to visualize due to condensation within contact slide media plates; and iv) Techniques involve growth of potentially harmful microorganisms, which must then be disposed of safely. This report describes the operation of a new culture-independent technique onboard the ISS for rapid analysis (within minutes) of endotoxin and -1, 3-glucan, found in the cell walls of gram-negative bacteria and fungi, respectively. This technique involves analysis of environmental samples with the Limulus Amebocyte Lysate (LAL) assay in a handheld device. This handheld device and sampling system is known as the Lab-On-a-Chip Application Development Portable Test System (LOCAD-PTS). A poster will be presented that describes a comparative study between LOCAD-PTS analysis and existing culture-based methods onboard the ISS; together with an exploratory survey of surface endotoxin throughout the ISS. It is concluded that while a general correlation between LOCAD-PTS and traditional culture-based methods should not necessarily be expected, a combinatorial approach can be adopted where both sets of data are used together to generate a more complete story of the microbial ecology on the ISS.

Maule, J.↗
NASA NTRS2018

Characterization of Rapid Charging Events Due to Sheath Capacitance and Impact on the International Space Station Plasma Hazard Process

During an Extravehicular Activity (EVA), if the Extravehicular Mobility Unit (EMU) makes galvanic contact with the International Space Station (ISS), a negative Floating Potential (FP) can lead to an arcing hazard when it exceeds -45.5 V, and a positive FP can produce a DC current high enough to stimulate the astronaut’s muscles (5 mA), and also cause a hazard. The Boeing Space Environments team developed and utilizes a Plasma Interaction Model (PIM) in order to calculate the ISS FP based on the plasma environment, ISS velocity, geomagnetic field, solar array and ISS orientation, and solar array regulation to support EVA planning operations. Presently, the model excludes the sheath capacitance, resulting in the total potential drop being across the dielectric surface of the vehicle. Data from the Floating Potential Measurement Unit (FPMU) show this assumption to be generally true. However, Rapid Charging Events (RCE) are often observed in the FPMU data at eclipse exit when the electron number density, Ne, is low (less than 5(sub e)10 m (exp-3)). During these events, the FP can rise more than 40 V in one to five seconds. There is then a relaxation phase where the FP drops back to the normal FP values. The PIM model is not capable of producing these RCEs. It was thought that the inclusion of the sheath in PIM could improve the charging predictions, particularly as related to RCEs. A parametric study was performed to determine what portion of the measured FP is across the sheath for a range of Ne experienced by the ISS, and if the inclusion of the sheath in PIM is necessary. Results show that the potential drop across the sheath is negligible at times when the N(sub e) is greater than 1(sub e)11 m-3. However, there appears to be a transitional region between 1(sub e)10 m(exp -3) and 1(sub e)11 m(exp -3) where the sheath capacitance becomes more significant. During those conditions the potential drop across the sheath can be larger than the potential drop across the dielectric for short periods (1-5 seconds). These results agree remarkably well with measurements made by the FPMU. The inclusion of the sheath explains why high charging measurements occur when the Ne is low at eclipse exit and even times when the solar arrays are not a significant driver (i.e., potentials often rise as the ISS flies through spread-F). Results also show that the RCEs are not a safety concern because the potential drop across the dielectric surface does not exceed -45.5 V. In that case, the EMU would not arc. This gives high confidence in the low probability of an arcing hazard occurring.

plasma environment↗
DOE OSTI2026

Quantitative Analysis of the Semiconductor–Electrolyte Interface Using Cyclic Voltammetry Measurements

Small changes in the chemical potential at a semiconductor interface can result in dramatic changes to the space-charge layer that underpins applications in the electronic and photovoltaic industries as well as in photoelectrochemical cells for fuel production. There has hence been great interest in techniques that directly probe the space-charge layer, yet many fail at the semiconductor–electrolyte interface due to the potential drop in the electric double-layer region of the electrolyte. This article demonstrates that photovoltages, obtained from straightforward cyclic voltammetry measurements, provide an experimental and quantitative approach for characterizing the semiconductor–electrolyte interface. Key parameters accessible through this approach include the flat-band potential ( E fb ), the fraction of the total potential that drops across the space-charge layer (γ sc ) and the electric double layer, as well as the surface recombination lifetime (τ s ). Here, we report photovoltage measurements for p -type Si(111) photoelectrodes in contact with electrolytes containing redox-active species with a range of known reduction potentials that exceed the 1.1 eV bandgap. In tetrabutylammonium [NBu 4 ] + electrolyte, the flat-band potential determined for hydrogen-terminated ( p -Si–H), methyl-terminated ( p -Si–CH 3 ), and chemically oxidized ( p -Si–cSiO x ) surfaces were −0.02, −0.31, and 0.30 V vs Fc +/0 , respectively, agreeing well with expected shifts arising from surface dipole modifications. The quantitative analysis also reveals that 67% of the applied bias drops across the space-charge layer for p -Si–H, 73% for p -Si–CH 3 , and only 44% for p -Si–cSiO x . The remaining potential drop is attributed to the interfacial surface layer, which consists of a molecular dipole or oxide overlayer, and the Helmholtz layer within the electrolyte. When the larger [NBu 4 ] + electrolyte was replaced with Li + , the flat-band position showed minimal changes, but the fraction of the potential drop across the space-charge layer increased significantly, consistent with the small cation altering the structure of the electric double layer.

electrolytes↗
NASA NTRS2016

Transmission Scheduling and Routing Algorithms for Delay Tolerant Networks

The challenges of data processing, transmission scheduling and routing within a space network present a multi-criteria optimization problem. Long delays, intermittent connectivity, asymmetric data rates and potentially high error rates make traditional networking approaches unsuitable. The delay tolerant networking architecture and protocols attempt to mitigate many of these issues, yet transmission scheduling is largely manually configured and routes are determined by a static contact routing graph. A high level of variability exists among the requirements and environmental characteristics of different missions, some of which may allow for the use of more opportunistic routing methods. In all cases, resource allocation and constraints must be balanced with the optimization of data throughput and quality of service. Much work has been done researching routing techniques for terrestrial-based challenged networks in an attempt to optimize contact opportunities and resource usage. This paper examines several popular methods to determine their potential applicability to space networks.

Space Networking↗
NASA NTRS1996

Report on Alternative Devices to Pyrotechnics on Spacecraft

Pyrotechnics accomplish many functions on today's spacecraft, possessing minimum volume/weight, providing instantaneous operation on demand, and requiring little input energy. However, functional shock, safety, and overall system cost issues, combined with emergence and availability of new technologies question their continued use on space missions. Upon request from the National Aeronautics and Space Administration's (NASA) Program Management Council (PMC), Langley Research Center (LaRC) conducted a survey to identify and evaluate state-of-the-art non-explosively actuated (NEA) alternatives to pyrotechnics, identify NEA devices planned for NASA use, and investigate potential interagency cooperative efforts. In this study, over 135 organizations were contacted, including NASA field centers, Department of Defense (DOD) and other government laboratories, universities, and American and European industrial sources resulting in further detailed discussions with over half, and 18 face-to-face briefings. Unlike their single use pyrotechnic predecessors, NEA mechanisms are typically reusable or refurbishable, allowing flight of actual tested units. NEAs surveyed include spool-based devices, thermal knife, Fast Acting Shockless Separation Nut (FASSN), paraffin actuators, and shape memory alloy (SMA) devices (e.g., Frangibolt). The electro-mechanical spool, paraffin actuator and thermal knife are mature, flight proven technologies, while SMA devices have a limited flight history. There is a relationship between shock, input energy requirements, and mechanism functioning rate. Some devices (e.g., Frangibolt and spool based mechanisms) produce significant levels of functional shock. Paraffin, thermal knife, and SMA devices can provide gentle, shock-free release but cannot perform critically timed, simultaneous functions. The FASSN flywheel-nut release device possesses significant potential for reducing functional shock while activating nearly instantaneously. Specific study recommendations include: (1) development of NEA standards, specifically in areas of material characterization, functioning rates, and test methods; (2) a systems level approach to assure successful NEA technology application; and (3) further investigations into user needs, along with industry/government system-level real spacecraft cost benefit trade studies to determine NEA application foci and performance requirements. Additional survey observations reveal an industry and government desire to establish partnerships to investigate remaining unknowns and formulate NEA standards, specifically those driven by SMAs. Finally, there is increased interest and need to investigate alternative devices for such functions as stage/shroud separation and high pressure valving. This paper summarizes results of the NASA-LaRC survey of pyrotechnic alternatives. State of-the-art devices with their associated weight and cost savings are presented. Additionally, a comparison of functional shock characteristics of several devices are shown, and potentially related technology developments are highlighted.

Lucy, M. H.↗