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At least 1,027 records · Page 57

All sources NASA NTRS DOE OSTI

NASA NTRS2016

Post-Flight Assessment of Avcoat Thermal Protection System for the Exploration Flight Test-1

On December 5, 2014 NASA conducted the first flight test of its next generation human-class Orion spacecraft. The flight was called the Exploration Flight Test -1 (EFT-1) which lasted for 4 hours and culminated into a re-entry trajectory at 9 km/s. This flight test of the 5-meter Orion Crew Module demonstrated various sub-systems including the Avcoat ablative thermal protection system (TPS) on the heat shield. The Avcoat TPS had been developed from the Apollo-era recipe with a few key modifications. The engineering for thermal sizing was supported by modeling, analysis, and ground tests in arc jet facilities. This paper will describe a postlfight analysis plan and present results from post-recovery inspections, data analysis from embedded sensors, TPS sample extraction and characterization in the laboratory. After the recovery of the vehicle, a full photographic survey and surface scans of the TPS were performed. The recovered vehicle showed physical evidence of flow disturbances, varying degrees of surface roughness, and excessive recession downstream of compression pads. The TPS recession was measured at more than 200 locations of interest on the Avcoat surface. The heat shield was then processed for sample extraction prior to TPS removal using the 7-Axis Milling machine at Marshall Space Flight Center. Around 182 rectangular TPS samples were extracted for subsequent analysis and investigation. The final paper will also present results of sample analysis. The planned investigation includes sidewall imaging, followed by image analysis to characterize TPS response by quantifying different layers in the char and pyrolysis zones. A full postmortem of the instrumentation and sensor ports will also be performed to confirm no adverse effects due to the sensors themselves. A subset of the samples will undergo structural testing and perform detailed characterization of any cracks and integrity of gore seams. Finally, the material will be characterized with layer-by-layer density measurements and SEM investigations to evaluate material morphology at microstructural level including identification of elements and compounds.

Aerothermodynamics↗

NASA NTRS1989

Numerical model of solar dynamic radiator for parametric analysis

Growth power requirements for Space Station Freedom will be met through addition of 25 kW solar dynamic (SD) power modules. The SD module rejects waste heat from the power conversion cycle to space through a pumped-loop, multi-panel, deployable radiator. The baseline radiator configuration was defined during the Space Station conceptual design phase and is a function of the state point and heat rejection requirements of the power conversion unit. Requirements determined by the overall station design such as mass, system redundancy, micrometeoroid and space debris impact survivability, launch packaging, costs, and thermal and structural interaction with other station components have also been design drivers for the radiator configuration. Extensive thermal and power cycle modeling capabilities have been developed which are powerful tools in Station design and analysis, but which prove cumbersome and costly for simple component preliminary design studies. In order to aid in refining the SD radiator to the mature design stage, a simple and flexible numerical model was developed. The model simulates heat transfer and fluid flow performance of the radiator and calculates area mass and impact survivability for many combinations of flow tube and panel configurations, fluid and material properties, and environmental and cycle variations. A brief description and discussion of the numerical model, it's capabilities and limitations, and results of the parametric studies performed is presented.

Rhatigan, Jennifer L.↗

NASA NTRS1989

Refurbishment of one-person regenerative air revitalization system

Regenerative processes for the revitalization of spacecraft atmospheres and reclamation of waste waters are essential for making long-term manned space missions a reality. Processes studied include: static feed water electrolysis for oxygen generation, Bosch carbon dioxide reduction, electrochemical carbon dioxide concentration, vapor compression distillation water recovery, and iodine monitoring. The objectives were to: provide engineering support to Marshall Space Flight Center personnel throughout all phases of the test program, e.g., planning through data analysis; fabricate, test, and deliver to Marshall Space Flight Center an electrochemical carbon dioxide module and test stand; fabricate and deliver an iodine monitor; evaluate the electrochemical carbon dioxide concentrator subsystem configuration and its ability to ensure safe utilization of hydrogen gas; evaluate techniques for recovering oxygen from a product oxygen and carbon dioxide stream; and evaluate the performance of an electrochemical carbon dioxide concentrator module to operate without hydrogen as a method of safe haven operation. Each of the tasks were related in that all focused on providing a better understanding of the function, operation, and performance of developmental pieces of environmental control and life support system hardware.

Powell, Ferolyn T.↗

NASA NTRS1994

High performance real-time flight simulation at NASA Langley

In order to meet the stringent time-critical requirements for real-time man-in-the-loop flight simulation, computer processing operations must be deterministic and be completed in as short a time as possible. This includes simulation mathematical model computational and data input/output to the simulators. In 1986, in response to increased demands for flight simulation performance, personnel at NASA's Langley Research Center (LaRC), working with the contractor, developed extensions to a standard input/output system to provide for high bandwidth, low latency data acquisition and distribution. The Computer Automated Measurement and Control technology (IEEE standard 595) was extended to meet the performance requirements for real-time simulation. This technology extension increased the effective bandwidth by a factor of ten and increased the performance of modules necessary for simulator communications. This technology is being used by more than 80 leading technological developers in the United States, Canada, and Europe. Included among the commercial applications of this technology are nuclear process control, power grid analysis, process monitoring, real-time simulation, and radar data acquisition. Personnel at LaRC have completed the development of the use of supercomputers for simulation mathematical model computational to support real-time flight simulation. This includes the development of a real-time operating system and the development of specialized software and hardware for the CAMAC simulator network. This work, coupled with the use of an open systems software architecture, has advanced the state of the art in real time flight simulation. The data acquisition technology innovation and experience with recent developments in this technology are described.

Cleveland, Jeff I., II↗

NASA NTRS1992

System requirements specification for SMART structures mode

Specified here are the functional and informational requirements for software modules which address the geometric and data modeling needs of the aerospace structural engineer. The modules are to be included as part of the Solid Modeling Aerospace Research Tool (SMART) package developed for the Vehicle Analysis Branch (VAB) at the NASA Langley Research Center (LaRC). The purpose is to precisely state what the SMART Structures modules will do, without consideration of how it will be done. Each requirement is numbered for reference in development and testing.

Source record↗

NASA NTRS1991

Probabilistic Structural Analysis Methods (PSAM) for select space propulsion system components

This annual report summarizes the work completed during the third year of technical effort on the referenced contract. Principal developments continue to focus on the Probabilistic Finite Element Method (PFEM) which has been under development for three years. Essentially all of the linear capabilities within the PFEM code are in place. Major progress in the application or verifications phase was achieved. An EXPERT module architecture was designed and partially implemented. EXPERT is a user interface module which incorporates an expert system shell for the implementation of a rule-based interface utilizing the experience and expertise of the user community. The Fast Probability Integration (FPI) Algorithm continues to demonstrate outstanding performance characteristics for the integration of probability density functions for multiple variables. Additionally, an enhanced Monte Carlo simulation algorithm was developed and demonstrated for a variety of numerical strategies.

Source record↗

DOE OSTI2022

Technoeconomic Analysis of Dye Sensitized Solar Cells (DSSCs) with WS 2 /Carbon Composite as Counter Electrode Material

Exploration of clean and renewable energy materials is necessary due to the coming energy crisis and environmental problems. Solar energy is one of the favorable energy sources because of the continuous energy reservoir and its affluence. Silicon-based solar devices are expensive due to their complicated production process, which limits this technology for urban and other commercial applications. Among the third generation of solar cells, Dye-Sensitized Solar Cells (DSSCs) have attracted widespread attention as potential cost-effective alternatives to silicon-based solar cells. In this paper, the commercializing potential of the DSSCs is investigated. A module is introduced where the materials, equipment, and distribution of direct manufacturing costs are calculated. The manufacturing costs and the Levelized Cost of Energy (LCOE) of these DSSCs for a system lifetime of 25 years were determined to be USD 22.40 per m 2 and USD 0.0438 per kWh and the module price of this technology is USD 0.18 per W and the total installed system cost is USD 0.88 per W in Kansas which suggest that this PV technology could challenge other leading PV technologies.

14 SOLAR ENERGY↗

DOE OSTI2025

Long-term calibration and validation of stability of the Auger Engineering Radio Array using the diffuse Galactic radio emission

The Auger Engineering Radio Array (AERA) measures radio emission from high-energy extensive air showers. Consisting of 153 autonomous radio-detector stations spread over 17 km^2, it detects radio waves in the frequency range of 30 to 80 MHz. Accurate characterization of the detector response is crucial for proper interpretation of the collected data. Previously, this was achieved through laboratory measurements of the analog chain and simulations and measurements of the antenna's directional response. In this paper, we perform an absolute calibration using the continuously monitored sidereal modulation of the diffuse Galactic radio emission. Calibration is done by comparing the average frequency spectra recorded by the stations with predictions from seven different models of the full radio sky, accounting for the system response, which includes the antenna, filters, and amplifiers. The analysis of the calibration constants over a period of seven years shows no relevant and no significant ageing effect in the AERA antennas. This result confirms the long-term stability of the detector stations and demonstrates the possibility for a radio detector to effectively monitor ageing effects of other detectors operating over extended periods.

Antennas↗

NASA NTRS1980

Study of curved glass photovoltaic module and module electrical isolation design requirements

The design of a 1.2 by 2.4 m curved glass superstrate and support clip assembly is presented, along with the results of finite element computer analysis and a glass industry survey conducted to assess the technical and economic feasibility of the concept. Installed costs for four curved glass module array configurations are estimated and compared with cost previously reported for comparable flat glass module configurations. Electrical properties of candidate module encapsulation systems are evaluated along with present industry practice for the design and testing of electrical insulation systems. Electric design requirements for module encapsulation systems are also discussed.

Source record↗

NASA NTRS1987

Thermal control of the Lidar In-Space Technology Experiment

The Lidar In-Space Technology Experiment (LITE) will employ lidar techniques to study the atmosphere from space. The LITE instrument will be flown in the Space Shuttle Payload Bay with an earth directed orientation. The experiment thermal control incorporates both active and passive techniques. The Laser Transmitter Module (LTM) and the system electronics will be actively cooled through the Shuttle pallet coolant loop. The receiver system and experiment platform will be passsively controlled through the use of insulation and component surface properties. This paper explains the thermal control techniques used and the analysis results, with primary focus on the receiver system.

Carlson, Ann B.↗

NASA NTRS1988

The performance of trellis coded multilevel DPSK on a fading mobile satellite channel

The performance of trellis-coded multilevel differential phase-shift-keying (MDPSK) modulation over Rician and Rayleigh fading channels is discussed. For operation at L-band, this signalling technique leads to a more robust system than the coherent system with dual pilot tone calibration previously proposed for UHF. The results are obtained using a combination of analysis and simulation. The analysis shows that the design criterion for trellis codes to be operated on fading channels with interleaving/deinterleaving is no longer free Euclidean distance. The correct design criterion for optimizing bit error probability of trellis coded MDPSD over fading channels is presented along with examples illustrating its application.

Simon, Marvin K.↗

NASA NTRS1990

Polarization considerations for optical systems II; Proceedings of the Meeting, San Diego, CA, Aug. 9-11, 1989

Various papers on polarization considerations for optical systems are presented. Individual topics addressed include: use of polarization methods in earth resources investigation, measurements of polarization scattering in the vacuum UV, the Space Shuttle as a polarization observation platform, analysis of spatial pseudodepolarizers in imaging systems, analysis of polarization effects in optical systems, and a low-polarization solar vector magnetograph. Consideration is given to polarization effects on astronomical spatial interferometry, measurement of the instrumental polarization of a high-resolution UV spectrometer, and the use of KD(asterisk)P modulators for polarization measurements of the sun.

Chipman, Russell A.↗

NASA NTRS1993

Optical communications and a comparison of optical technologies for a high data rate return link from Mars

The important principles of direct- and heterodyne-detection optical free-space communications are reviewed. Signal-to-noise-ratio (SNR) and bit-error-rate (BER) expressions are derived for both the direct-detection and heterodyne-detection optical receivers. For the heterodyne system, performance degradation resulting from received-signal and local oscillator-beam misalignment and laser phase noise is analyzed. Determination of interfering background power from local and extended background sources is discussed. The BER performance of direct- and heterodyne-detection optical links in the presence of Rayleigh-distributed random pointing and tracking errors is described. Finally, several optical systems employing Nd:YAG, GaAs, and CO2 laser sources are evaluated and compared to assess their feasibility in providing high-data-rate (10- to 1000-Mbps) Mars-to-Earth communications. It is shown that the root mean square (rms) pointing and tracking accuracy is a critical factor in defining the system transmitting laser-power requirements and telescope size and that, for a given rms error, there is an optimum telescope aperture size that minimizes the required power. The results of the analysis conducted indicate that, barring the achievement of extremely small rms pointing and tracking errors (less than 0.2 microrad), the two most promising types of optical systems are those that use an Nd:YAG laser (lambda = 1.064 microns) and high-order pulse position modulator (PPM) and direct detection, and those that use a CO2 laser (lambda = 10.6 microns) and phase shifting keying homodyne modulation and coherent detection. For example, for a PPM order of M = 64 and an rms pointing accuracy of 0.4 microrad, an Nd:YAG system can be used to implement a 100-Mbps Mars link with a 40-cm transmitting telescope, a 20-W laser, and a 10-m receiving photon bucket. Under the same conditions, a CO2 system would require 3-m transmitting and receiving telescopes and a 32-W laser to implement such a link. Other types of optical systems, such as a semiconductor laser systems, are impractical in the presence of large rms pointing errors because of the high power requirements of the 100-Mbps Mars link, even when optimal-size telescopes are used.

Spence, Rodney L.↗

NASA NTRS1992

Study of pseudo noise CW diode laser for ranging applications

A new Pseudo Random Noise (PN) modulated CW diode laser radar system is being developed for real time ranging of targets at both close and large distances (greater than 10 KM) to satisy a wide range of applications: from robotics to future space applications. Results from computer modeling and statistical analysis, along with some preliminary data obtained from a prototype system, are presented. The received signal is averaged for a short time to recover the target response function. It is found that even with uncooperative targets, based on the design parameters used (200-mW laser and 20-cm receiver), accurate ranging is possible up to about 15 KM, beyond which signal to noise ratio (SNR) becomes too small for real time analog detection.

Lee, Hyo S.↗

NASA NTRS1999

The Low-Mass X-Ray Binary X1832-330 in the Globular Cluster NGC 6652: A Serendipitous ASCA Observation

The Low Mass X-ray Binary (LMXB) X1832-330 in NGC 6652 is one of about 10 bright X-ray sources to have been discovered in Globular Clusters. We report on a serendipitous ASCA observation of this Globular Cluster LMXB, during which a Type I burst was detected and the persistent, non-burst emission of the source was at its brightest level recorded to date. No orbital modulation was detected, which argues against a high inclination for the X1832-330 system. The spectrum of the persistent emission can be fit with a power law plus a partial covering absorber, although other models are not ruled out. Our time-resolved spectral analysis through the burst shows, for the first time, clear evidence for spectral cooling from kT = 2.4 +/- 0.6 keV to kT = 1.0 +/- 0.1 keV during the decay. The measured peak flux during the burst is approximately 10% of the Eddington luminosity for a 1.4 Solar Mass neutron star. These are characteristic of a Type I burst, in the context of the relatively low quiescent luminosity of X1832-330.

Mukai, Koji↗

NASA NTRS2003

Microgravity Emissions Laboratory Testing of the Light Microscopy Module Control Box Fan

The Microgravity Emissions Laboratory (MEL) was developed at the NASA Glenn Research Center for the characterization, simulation, and verification of the International Space Station (ISS) microgravity environment. This Glenn lab was developed in support of the Fluids and Combustion Facility (FCF). The MEL is a six-degrees-of-freedom inertial measurement system that can characterize the inertial response forces (emissions) of components, subrack payloads, or rack-level payloads down to 10 7g. The inertial force output data generated from the steady-state or transient operations of the test article are used with finite element analysis, statistical energy analysis, and other analysis tools to predict the on-orbit environment at specific science or rack interface locations. Customers of the MEL have used benefits in isolation performance testing in defining available attenuation during the engineering hardware design phase of their experiment s development. The Light Microscopy Module (LMM) Control Box (LCB) fan was tested in the MEL in June and July of 2002. The LMM is planned as a remotely controllable on-orbit microscope subrack facility that will be accommodated in an FCF Fluids Integrated Rack on the ISS. The disturbances measured in the MEL test resulted from operation of the air-circulation fan within the LCB. The objectives of the testing were (1) to identify an isolator to be added to the LCB fan assembly to reduce fan-speed harmonics and (2) to identify the fan-disturbance forcing functions for use in rack-response analysis of the LMM and Fluids Integrated Rack facility. This report describes the MEL, the testing process, and the results from ground-based MEL LCB fan testing.

McNelis, Anne M.↗

DOE OSTI2023

Novel Module Architecture for Lower CapEx and Improved Recyclability for c-Si PV Modules

Photovoltaic (PV) energy production is currently increasing at a rate at which recycling is becoming necessary. A novel module architecture has been demonstrated that has potential for high value recycling for c-Si PV. This architecture eliminates the vacuum lamination process and cross-linked en capsulants. Functioning prototypes of c-Si have been fabricated for stress testing in collaboration with NREL. These modules are being tested against traditionally manufactured modules. Based on preliminary results, this module architecture is a potentially viable solution for improving the manufacturing cost and recyclability of PV modules while retaining module performance.

computer architecture↗

NASA NTRS2009

Port-O-Sim Object Simulation Application

Port-O-Sim is a software application that supports engineering modeling and simulation of launch-range systems and subsystems, as well as the vehicles that operate on them. It is flexible, distributed, object-oriented, and realtime. A scripting language is used to configure an array of simulation objects and link them together. The script is contained in a text file, but executed and controlled using a graphical user interface. A set of modules is defined, each with input variables, output variables, and settings. These engineering models can be either linked to each other or run as standalone. The settings can be modified during execution. Since 2001, this application has been used for pre-mission failure mode training for many Range Safety Scenarios. It contains range asset link analysis, develops look-angle data, supports sky-screen site selection, drives GPS (Global Positioning System) and IMU (Inertial Measurement Unit) simulators, and can support conceptual design efforts for multiple flight programs with its capacity for rapid six-degrees-of-freedom model development. Due to the assembly of various object types into one application, the application is applicable across a wide variety of launch range problem domains.

Lanzi, Raymond J.↗