Results for “conjunction assessment” — Page 5

NASA NTRS2024

Expansion of Check-Cases for 6DOF Simulation

This is the Appendix containing a description of the solution for Case 1 in the assessment, “Expansion of Check-Cases for 6DOF Simulation”. For cases of spherical gravity, it is possible to provide a two-body solution without recourse to numerical integration and thus it is accurate to machine precision. Python code for a Keplerian Propagator (propagate.py) which produced a reference trajectory for Case 1 is provided in this appendix. There is also code for generating test cases which was used as an independent verification of the propagator. This is a high-level description of the algorithm employed. The documentation of each function includes implementation details, including equations for each task.

Modeling↗

NASA NTRSDate not supplied

Multifaceted Considerations for Fission Surface Power Radiation Shielding Design

The purpose of the Fission Surface Power (FSP) nuclear system is to provide energy on the Moon and Mars for supporting their exploration and colonization. The FSP design and deployment can leverage the past research and development work in areas, such as reactor design, but such crucial components as radiation shielding and instrumentation still need material and manufacturing studies, modeling, and testing. The shielding components are needed for the protection of humans, electronics, and sensitive components. They are essential system components, but they are often the heaviest components of the system for which each kilogram matters. Different material combinations and layouts are possible. The studies presented were focused on the evaluation of several options. The initial analysis included their performance assessment, initial temperature distribution evaluation and manufacturability considerations. Several feasible shield design options were identified and discussed in this paper, as well.

Fission Surface Power↗

NASA NTRS2026

The Habitable Worlds Observatory Technology Development Plan

The Habitable Worlds Observatory (HWO) is NASA’s next large space telescope, selected by the 2020 Decadal Survey in Astronomy and Astrophysics to search for and characterize habitable exoplanets while enabling a broad range of transformative astrophysics. In August 2024, the HWO Technology Maturation Project Office (TMPO) was formed to begin exploring the HWO science, technology, and mission architectures toward a Mission Concept Review (MCR) at the end of the decade. A primary deliverable of this effort is this technology development plan that identifies critical technologies that enable the mission, defines a process for assessing the readiness of those technologies, and outlines a strategy for developing those technologies to a Technology Readiness Level (TRL) of 5 before the MCR. This document covers technologies organized along three “tracks”: Coronagraph System technologies, Ultra-stable Telescope System technologies, and High-sensitivity Ultraviolet and Visible Instrumentation technologies. Additional emerging and enhancing technologies are also discussed.

technology development↗

NASA NTRS1992

Microgravity Effects on Standardized Cognitive Performance Measures

The purpose of this experiment, selected to fly on the International Microgravity Laboratory (IML-2) Spacelab mission, is to determine the effects of microgravity upon the cognitive skills which are critical to successful performance of many tasks on board the Space Shuttle. Six tests from the Unified Tri-service Cognitive Performance Assessment Battery (UTC-PAB) will be administered to the Mission Specialists to fulfill the goals of this experiment. These tests are based upon current theoretical models of human performance and the hypothesized effects of microgravity. The principle objective is the identification of the effects of microgravity upon specific information processing skills affecting performance from those of fatigue and shifts in work/rest cycles. Multiple measures of both short and long term fatigue will be obtained and used as a major independent variable for the analysis of these performance data. Scientific supporting studies will determine optimum practice and performance testing schedules for the astronauts. The same tests will be used post-flight to collect data on the recovery of any cognitive performance impairment compared with pre-flight, baseline levels.

Samuel G Schiflett↗

NASA NTRSDate not supplied

Evaluation of Particle Degradation of a Ytterbium Disilicate Gas Turbine Coating in a Combustion Environment

Ytterbium disilicate (Yb2Si2O7) is a state-of-the-art topcoat material used in environmental barrier coatings (EBCs) to protect SiC-SiC composites from water vapor corrosion in gas turbine engines. However, it’s degradation by thermochemical and thermomechanical particle interactions may limit its use in next generation engine systems. Several static furnace tests have been performed on Yb2Si2O7 to elucidate methods of degradation, although dynamic testing in an engine-relevant environment has not been carried out. Ultimately, testing and evaluation of materials that incorporates all environmental damage modes will allow for an accurate assessment of long-term durability and operating lifetime. This work details the investigation of particle-induced erosion and corrosion of Yb2Si2O7 in NASA Glenn’s Erosion Burner Rig Facility. Coating durability was investigated as a function of test temperature, particle size, and deposition rate. Thermal cycling was also incorporated into testing to determine the interplay of heating/cooling cycles with particle degradation. Overall, these analyses will be used to determine coating robustness in an engine relevant environment.

Jamesa L Stokes↗

NASA NTRSDate not supplied

Evaluation of Particle Degradation of a Ytterbium Disilicate Gas Turbine Coating in a Combustion Environment

Ytterbium disilicate (Yb2Si2O7) is a state-of-the-art topcoat material used in environmental barrier coatings (EBCs) to protect SiC-SiC composites from water vapor corrosion in gas turbine engines. However, it’s degradation by thermochemical and thermomechanical particle interactions may limit its use in next generation engine systems. Several static furnace tests have been performed on Yb2Si2O7 to elucidate methods of degradation, although dynamic testing in an engine-relevant environment has not been carried out. Ultimately, testing and evaluation of materials that incorporates all environmental damage modes will allow for an accurate assessment of long-term durability and operating lifetime. This work details the investigation of particle-induced erosion and corrosion of Yb2Si2O7 in NASA Glenn’s Erosion Burner Rig Facility. Coating durability was investigated as a function of test temperature, particle size, and deposition rate. Thermal cycling was also incorporated into testing to determine the interplay of heating/cooling cycles with particle degradation. Overall, these analyses will be used to determine coating robustness in an engine relevant environment.

Jamesa L Stokes↗

NASA NTRSDate not supplied

Application of System-Theoretic Process Analysis (STPA) to a NASA Concept Electric Aircraft Battery System

System-Theoretic Process Analysis (STPA) is a systems-based hazard analysis method that identifies unsafe interactions and control deficiencies in complex systems but has been rarely used for NASA programs in favor of more well-established hazard analyses. To evaluate its applicability, a NASA Safety and Mission Assurance (SMA) team applied the STPA method to an early-stage hybrid electrified aircraft concept, focusing on the energy storage system and electric powertrain. Objectives include assessing STPA’s value relative to traditional methods and its suitability for early design phases. Activities include team training, system review, detailed STPA execution, and comparison with traditional analyses. Findings show STPA provides a structured, comprehensive hazard evaluation and can identify additional risks by expanding analysis boundaries. However, traditional methods can yield similar results when applied rigorously, though they typically require more mature designs. Overall, STPA is a valuable addition, particularly for early development, informing safety requirements and supporting preliminary hazard analyses. Further pilot applications are recommended.

Electric Aviation↗

NASA NTRS2026

Raising TRL of Your Lunar Payload

Preparing payloads for the lunar surface requires rigorous testing that accurately captures the extreme environmental and operational conditions. This presentation provides an overview of the lunar relevant test capabilities at NASA JSC’s Astromaterials Research and Exploration Science (ARES) laboratories as well as the Energy System Test Area (ESTA) Lunar Development and Test Facility. These facilities allow teams to assess hardware performance in dusty vacuum environments, characterize interactions with high fidelity lunar regolith simulants, evaluate mechanical and thermal durability, and understand the effects of micrometeoroid and orbital debris impacts—critical factors for certifying payloads that will operate on the lunar surface or in orbit. While Lunar power challenges such as variable illumination, extreme temperatures, and dust driven degradation will be briefly summarized, the focus of this talk is on how JSC’s test infrastructure enables developers to validate designs, reduce mission risk, and ensure compatibility with CLPS and Artemis objectives. NASA JSC’s expertise and experience help industry, academic, and government teams prepare robust hardware ready for successful delivery and operation on the surface of the Moon.

Lunar Regolith Simulant↗

NASA NTRS1999

Solid Inflammability Boundary at Low Speed (SIBAL)

This research program is concerned with the effect of low-speed, concurrent flow on the spreading and extinction processes of flames over solid fuels. The primary objective is to verify the theoretically predicted extinction boundary, using oxygen percentage and flow velocity as coordinates. In particular, we are interested in the low-speed quenching limits and the existence of the critical oxygen flammability limit. Detailed flame spread characteristics, including flame spread rate, flame size, and flame structure are sought. Since the predicted flame behavior depends on the inclusion of flame and surface radiation, the measured results will also be used to assess the importance of radiative heat transfer by direct comparison to a comprehensive numerical model. This project passed the Science Concept Review (SCR) in 1996. As a result, the experiment continues on the flight definition path, and is currently scheduled to be performed in the Space Station Combustion Integrated Rack (CIR). We present an overview of recent and ongoing work, including selected experimental and theoretical topics.

James S T'ien↗

NASA NTRS2026

Raising TRL of Your Lunar Payload

Preparing payloads for the lunar surface requires rigorous testing that accurately captures the extreme environmental and operational conditions. This presentation provides an overview of the lunar relevant test capabilities at NASA JSC’s Astromaterials Research and Exploration Science (ARES) laboratories as well as the Energy System Test Area (ESTA) Lunar Development and Test Facility. These facilities allow teams to assess hardware performance in dusty vacuum environments, characterize interactions with high fidelity lunar regolith simulants, evaluate mechanical and thermal durability, and understand the effects of micrometeoroid and orbital debris impacts—critical factors for certifying payloads that will operate on the lunar surface or in orbit. While Lunar power challenges such as variable illumination, extreme temperatures, and dust driven degradation will be briefly summarized, the focus of this talk is on how JSC’s test infrastructure enables developers to validate designs, reduce mission risk, and ensure compatibility with CLPS and Artemis objectives. NASA JSC’s expertise and experience help industry, academic, and government teams prepare robust hardware ready for successful delivery and operation on the surface of the Moon.

Laboratories↗

NASA NTRS1994

Thermal Testing of High Performance: Thermal Barrier Coatings for Turbine Blades

A 350 micron thick 7 wt.% Y 2 O 3 -ZrO 2 (7YSZ) ceramic Thermal Barrier Coating (TBC) was manufactured in an argon atmosphere and with a strictly controlled substrate temperature on flat IN 600 samples and on IN 100 aircraft turbine blades. This new atmosphere and temperature controlled spraying (ATCS) allows the reduction of the residual stresses and an improvement in the microstructure and in the mechanical properties of the coating. The good performance of these new TBC's was assessed in thermal fatigue and in thermal shock tests carried out in air at 1100°C and at 1280°C respectively. The oxidation rate of the metal-ceramic interface was measured at 1100°C. Failure of the TBC's was induced only by the deterioration (like oxidation, cracking, ...) of the uncoated parts of the samples, as testing temperature was too severe for the base metals. Spalling was thereafter driven by compressive stresses near the aluminum oxide layer at the metal-ceramic interface. The results of these tests underline the good quality of the ceramic coating manufactured by the new ATCS technology.

L Bertamini↗

NASA NTRS2011

Thermal Cycling and Isothermal Deformation Response of Polycrystalline NiTi: Simulations vs. Experiment

A recent microstructure-based FEM model that couples crystal-based plasticity, the B2<-> MB190 phase transformation and anisotropic elasticity at the grain scale is calibrated to recent data for polycrystalline NiTi (49.9 at.% Ni). Inputs include anisotropic elastic properties, texture and differential scanning calorimetry data, as well as a subset of recent isothermal deformation and load-biased thermal cycling data. The model is assessed against additional experimental data. Several experimental trends are captured - in particular, the transformation strain during thermal cycling monotonically increases and reaches a peak with increasing bias stress. This is achieved, in part, by modifying the martensite hardening matrix proposed by Patoor et al. [Patoor E, Eberhardt A, Berveiller M. J Phys IV 1996;6:277]. Some experimental trends are underestimated - in particular, the ratcheting of macrostrain during thermal cycling. This may reflect a model limitation that transformation-plasticity coupling is captured on a coarse (grain) scale but not on a fine (martensitic plate) scale.

Phase Transformations↗

NASA NTRS2026

Optimization of a 10–Step Reduced CH₄/O₂ Combustion Mechanism for RDRE Applications

A 10-step, 9-species reduced mechanism for methane/oxygen combustion is evaluated and optimized for use in rotating detonation rocket engine (RDRE) simulations at an operating pressure of 10 bar. The mechanism is assessed against GRI-Mech 3.0 for ignition delay times, adiabatic equilibrium temperature and species, Chapman-Jouguet (CJ) detonation parameters, and laminar flame speed. A sequential Nelder–Mead optimization procedure is applied to the rate constants of reactions R1, R4, and R5, targeting ignition delay agreement over the equivalence ratio range φ = 1.0–1.4 and temperature range T = 1400–2000 K. The optimized mechanism achieves ignition delay agreement within 28% of GRI-Mech 3.0 for the temperature range relevant to RDRE operation (τ ≥ 5 μs). Adiabatic equilibrium temperatures and CJ detonation parameters are reproduced within 0.15% of GRI-Mech 3.0 values, confirming thermodynamic consistency of the mechanism. Laminar flame speed predictions deviate significantly from GRI-Mech 3.0, which is attributed to the absence of HO₂ chemistry in the reduced mechanism; this limitation does not affect RDRE simulation fidelity since laminar flame propagation is of secondary importance in RDREs.

Computational Fluid Dynamics↗

NASA NTRS2026

Parabolic Deformable Mirror Project Development and Device Characterization

Existing state-of-the-art wavefront sensing and control setups for the imaging of exoplanets utilize two high-actuator count flat deformable mirrors (DMs) to control both phase and amplitude aberrations. One of the objectives of the Exoplanet Spectroscopy (ExoSpec) project at Goddard Space Flight Center (GSFC) is to improve upon this regime through the development of parabolic deformable mirrors (PDMs), which can address several of the key limitations in existing setups. Specifically, the need for flat DMs to be located in conjugate pupil planes drives unique packaging challenges that can be overcome by allowing the off-axis imaging elements to be controllable as well. In addition, simulations show that the use of deformable powered elements will increase the overall controllable bandwidth, up to 35% over 5-12 lambda/D. To pursue this effort, the ExoSpec group has begun testing a first-generation parabolic DM, which is already informing a second generation design. This paper will provide a comprehensive update on its characterization, including influence function measurements, linearity analysis, closed-loop wavefront control performance, and thermal stability assessment.

spectroscopy↗

NASA NTRS1993

Piloting Vertical Flight Aircraft: A Conference on Flying Qualities and Human Factors

This document contains papers from a specialists' meeting entitled "Piloting Vertical Flight Aircraft. A Conference on Flying Qualities and Human Factors." The conference was co-sponsored by the American Helicopter Society--San Francisco Bay Chapter, and the NASA Ames Research Center. It was held January 20-22, 1993 at the Sheraton Hotel Fisherman's Wharf, San Francisco, California. Vertical flight aircraft, including helicopters and a variety of Vertical Takeoff and Landing (VTOL) concepts, place unique requirements on human perception, control, and performance for the conduct of their design missions. The intent of this conference was to examine, for these vehicles, advances in: (1) design of flight control systems for ADS-33C standards; (2) assessment of human factors influences of cockpit displays and operational procedures; (3) development of VTOL design and operational criteria; and (4) development of theoretical methods or models for predicting pilot-vehicle performance and mission suitability. Recognizing that human capabilities and limitations form an integral aspect of the operations for these classes of vehicles, a secondary goal of the conference was to provide an initial venue for enhanced interaction between human factors and handling qualities specialists.

Helicopter↗

NASA NTRSDate not supplied

Atmospheric, Non-Combusting Droplet Sizing and Spray Imaging Results From a Non-Proprietary Aero Gas Turbine Engine Pressure Swirl Atomizer using Shadowgraphy and Planar Laser Scatter

Members from industry and federal agencies of the United States have developed a collaborating group focused on improving the understanding of the atomization processes common to gas turbine engines. The group is aimed on providing high quality data using x-ray diagnostics in the internal geometry and the near-field dense spray as well as optical diagnostics in the visible spectrum, downstream of the nozzle. This paper reports results from one of the two non-proprietary injectors designs from the group: the primary-secondary injector. In particular, we characterize the spray from only the primary, pressure-swirl atomizing circuit using water through the nozzle. We observed Sauter mean diameter decreased with increased water pressure drop across the nozzle. SMD was also collected at three axial distances and showed decreased size with distance from the nozzle. Planar laser sheet droplet scattering provided qualitative assessment of the spray. Higher water pressure drops provided better atomization than lower pressure drops. The addition of swirling air flow through the injector alleviates and improves the atomization quality, particularly at the lower water pressure drops.

optical diagnostics↗

NASA NTRS2026

Advanced Materials Testing Plan for the Space Suit Portable Life Support System

The Space Suit Portable Life Support System (PLSS) has a tight mass requirement to meet while also meeting other requirements for supporting a crewmember in space, on the Moon, or on Mars. To meet these requirements, atypical materials must be considered to close the mass budget allocations. However, many of these materials and processes are relatively new and untested. Therefore, initial analysis and testing of some new and advanced processes have been conducted following a roadmap presented last year. This material testing has focused primarily on thermoplastics, both additively manufactured and machined, to assess plating and fastening operations that will be required. These processes will provide additional strength and shielding capability typically only achieved with metallics. This testing has also helped to define a forward plan to certify these materials and processes for critical spaceflight applications. This report will review testing plated thermoplastics both for strength and thermal properties. It will also review fastener and fastening options and look at insert and fastener testing. It will also review state-of-the-art methods being considered elsewhere and some additional testing being conducted. Using the testing results researched here, there will be recommendations on applications for each of these types of methods going forward.

Ryan Ogilvie↗

NASA NTRS2026

Advanced Materials Testing Plan for the Space Suit Portable Life Support System

The Space Suit Portable Life Support System (PLSS) has a tight mass requirement to meet while also meeting other requirements for supporting a crewmember in space, on the Moon, or on Mars. To meet these requirements, atypical materials must be considered to close the mass budget allocations. However, many of these materials and processes are relatively new and untested. Therefore, initial analysis and testing of some new and advanced processes have been conducted following a roadmap presented last year. This material testing has focused primarily on thermoplastics, both additively manufactured and machined, to assess plating and fastening operations that will be required. These processes will provide additional strength and shielding capability typically only achieved with metallics. This testing has also helped to define a forward plan to certify these materials and processes for critical spaceflight applications. This report will review testing plated thermoplastics both for strength and thermal properties. It will also review fastener and fastening options and look at insert and fastener testing. It will also review state-of-the-art methods being considered elsewhere and some additional testing being conducted. Using the testing results researched here, there will be recommendations on applications for each of these types of methods going forward.

Ryan Ogilvie↗