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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS2021

Global Intercomparison of hyper-resolution ECOSTRESS coastal sea surface temperature measurements from the Space Station with VIIRS-N20

The ECOSTRESS multi-channel thermal radiometer on the Space Station has an unprecedented spatial resolution of 70 m and a return time of hours to 5 days. It resolves details of oceanographic features not detectable in imagery from MODIS or VIIRS, and has open-ocean coverage, unlike Landsat. We calibrated two years of ECOSTRESS sea surface temperature observations with L2 data from VIIRS-N20 (2019–2020) worldwide but especially focused on important upwelling systems currently undergoing climate change forcing. Unlike operational SST products from VIIRS-N20, the ECOSTRESS surface temperature algorithm does not use a regression approach to determine temperature, but solves a set of simultaneous equations based on first principles for both surface temperature and emissivity. We compared ECOSTRESS ocean temperatures to well-calibrated clear sky satellite measurements from VIIRS-N20. Data comparisons were constrained to those within 90 min of one another using co-located clear sky VIIRS and ECOSTRESS pixels. ECOSTRESS ocean temperatures have a consistent 1.01 ◦C negative bias relative to VIIRS-N20, although deviation in brightness temperatures within the 10.49 and 12.01 µm bands were much smaller. As an alternative, we compared the performance of NOAA, NASA, and U.S. Navy operational split-window SST regression algorithms taking into consideration the statistical limitations imposed by intrinsic SST spatial autocorrelation and applying corrections on brightness temperatures. We conclude that standard bias-correction methods using already validated and well-known algorithms can be applied to ECOSTRESS SST data, yielding highly accurate products of ultra-high spatial resolution for studies of biological and physical oceanography in a time when these are needed to properly evaluate regional and even local impacts of climate change.

Nicolas Weidberg↗
NASA NTRS2024

FRAAME Version 1.0 User Manual

The code for Forced Response Aeromechanics Analysis in a MATLAB-based (The MathWorks, Inc.) Environment (FRAAME Version 1.0) was developed for internal use in aeromechanics efforts undertaken at the NASA Glenn Research Center for computing turbomachine component forced response and Goodman diagrams via modal summation method. The main working script (FRAAMEv1.m) allows users to input case-specific manual inputs while the triple-nested loop invokes functions to compute forced response per blade, per nodal diameter, and per mode. Secondly, forced response values are applied to modal stresses to compute complex Von Mises stress values and generate Goodman diagrams per blade, per nodal diameter, and per mode using a linear modal summation method. Currently, this code functions in the Windows (Microsoft Corporation) operating system using MATLAB Version R2023a, but it can be adapted for use in the Linux (Linus Torvalds) operating system by changing the appropriate file path structure in the main script, as well as functions that call external results files.

Aeromechanics↗
NASA NTRS2010

High-Speed Operation of Interband Cascade Lasers

Optical sources operating in the atmospheric window of 3-5 microns are of particular interest for the development of free-space optical communication link. It is more advantageous to operate the free-space optical communication link in 3-5-microns atmospheric transmission window than at the telecom wavelength of 1.5 m due to lower optical scattering, scintillation, and background radiation. However, the realization of optical communications at the longer wavelength has encountered significant difficulties due to lack of adequate optical sources and detectors operating in the desirable wavelength regions. Interband Cascade (IC) lasers are novel semiconductor lasers that have a great potential for the realization of high-power, room-temperature optical sources in the 3-5-microns wavelength region, yet no experimental work, until this one, was done on high-speed direct modulation of IC lasers. Here, highspeed interband cascade laser, operating at wavelength 3.0 m, has been developed and the first direct measurement of the laser modulation bandwidth has been performed using a unique, highspeed quantum well infrared photodetector (QWIP). The developed laser has modulation bandwidth exceeding 3 GHz. This constitutes a significant increase of the IC laser modulation bandwidth over currently existing devices. This result has demonstrated suitability of IC lasers as a mid-IR light source for multi-GHz free-space optical communications links

Soibel, Alexander↗
NASA NTRS1996

Design, Fabrication and Testing of Multilayer Coated X-Ray Optics for the Water Window Imaging X-Ray Microscope

Hoover et. al. built and tested two imaging Schwarzschild multilayer microscopes. These instruments were constructed as prototypes for the "Water Window Imaging X-Ray Microscope," which is a doubly reflecting, multilayer x-ray microscope configured to operate within the "water window." The "water window" is the narrow region of the x-ray spectrum between the K absorption edges of oxygen (lamda = 23.3 Angstroms) and of carbon (lamda = 43.62 Angstroms), where water is relatively highly transmissive and carbon is highly absorptive. This property of these materials, thus permits the use of high resolution multilayer x-ray microscopes for producing high contrast images of carbon-based structures within the aqueous physiological environments of living cells. We report the design, fabrication and testing of multilayer optics that operate in this regime.

Spencer, Dwight C.↗
NASA NTRS2014

CEO Sites Mission Management System (SMMS)

Late in fiscal year 2011, the Crew Earth Observations (CEO) team was tasked to upgrade its science site database management tool, which at the time was integrated with the Automated Mission Planning System (AMPS) originally developed for Earth Observations mission planning in the 1980s. Although AMPS had been adapted and was reliably used by CEO for International Space Station (ISS) payload operations support, the database structure was dated, and the compiler required for modifications would not be supported in the Windows 7 64-bit operating system scheduled for implementation the following year. The Sites Mission Management System (SMMS) is now the tool used by CEO to manage a heritage Structured Query Language (SQL) database of more than 2,000 records for Earth science sites. SMMS is a carefully designed and crafted in-house software package with complete and detailed help files available for the user and meticulous internal documentation for future modifications. It was delivered in February 2012 for test and evaluation. Following acceptance, it was implemented for CEO mission operations support in April 2012. The database spans the period from the earliest systematic requests for astronaut photography during the shuttle era to current ISS mission support of the CEO science payload. Besides logging basic image information (site names, locations, broad application categories, and mission requests), the upgraded database management tool now tracks dates of creation, modification, and activation; imagery acquired in response to requests; the status and location of ancillary site information; and affiliations with studies, their sponsors, and collaborators. SMMS was designed to facilitate overall mission planning in terms of site selection and activation and provide the necessary site parameters for the Satellite Tool Kit (STK) Integrated Message Production List Editor (SIMPLE), which is used by CEO operations to perform daily ISS mission planning. The CEO team uses the SMMS for three general functions - database queries of content and status, individual site creation and updates, and mission planning. The CEO administrator of the science site database is able to create or modify the content of sites and activate or deactivate them based on the requirements of the sponsors. The administrator supports and implements ISS mission planning by assembling, reporting, and activating mission-specific site selections for management; deactivating sites as requirements are met; and creating new sites, such as International Charter sites for disasters, as circumstances warrant. In addition to the above CEO internal uses, when site planning for a specific ISS mission is complete and approved, the SMMS can produce and export those essential site database elements for the mission into XML format for use by onboard Earth-location systems, such as Worldmap. The design, development, and implementation of the SMMS resulted in a superior database management system for CEO science sites by focusing on the functions and applications of the database alone instead of integrating the database with the multipurpose configuration of the AMPS. Unlike the AMPS, it can function and be modified within the existing Windows 7 environment. The functions and applications of the SMMS were expanded to accommodate more database elements, report products, and a streamlined interface for data entry and review. A particularly elegant enhancement in data entry was the integration of the Google Earth application for the visual display and definition of site coordinates for site areas defined by multiple coordinates. Transfer between the SMMS and Google Earth is accomplished with a Keyhole Markup Language (KML) expression of geographic data (see figures 3 and 4). Site coordinates may be entered into the SMMS panel directly for display in Google Earth, or the coordinates may be defined on the Google Earth display as a mouse-controlled polygonal definition and transferred back into the SMMS as KML input. This significantly reduces the possibility of errors in coordinate entries and provides visualization of the scale of the site being defined. CEO now has a powerful tool for managing and defining sites on the Earth's surface for both targets of astronaut photography or other onboard remote sensing systems. It can also record and track results by sponsor, collaborator, or type of study.

Trenchard, Mike↗
NASA NTRS1987

Resource sharing on CSMA/CD networks in the presence of noise

Resource sharing on carrier sense multiple access with collision detection (CSMA/CD) networks can be accomplished by using window-control algorithms for bus contention. The window-control algorithms are designed to grant permission to transmit to the station with the minimum contention parameter. Proper operation of the window-control algorithm requires that all stations sense the same state of the newtork in each contention slot. Noise causes the state of the network to appear as a collision. False collisions can cause the window-control algorithm to terminate without isolating any stations. A two-phase window-control protocol and approximate recurrence equation with noise as a parameter to improve the performance of the window-control algorithms in the presence of noise are developed. The results are compared through simulation, with the approximate recurrence equation yielding the best overall performance. Noise is even a bigger problem when it is not detected by all stations. In such cases it is possible for the window boundaries of the contending stations to become out of phase. Consequently, it is possible to isolate a station other than the one with the minimum contention parameter. To guarantee proper isolation of the minimum, a broadcast phase must be added after the termination of the algorithm. The protocol required to correct the window-control algorithm when noise is not detected by all stations is discussed.

Dinschel, Duane Edward↗
NASA NTRS1984

A Nomographic Methodology for Use in Performance Trade-Off Studies of Parabolic Dish Solar Power Modules

A simple graphical method was developed to undertake technical design trade-off studies for individual parabolic dish models comprising a two-axis tracking parabolic dish with a cavity receiver and power conversion assembly at the focal point. The results of these technical studies are then used in performing the techno-economic analyses required for determining appropriate subsystem sizing. Selected graphs that characterize the performance of subsystems within the module were arranged in the form of a nomogram that would enable an investigator to carry out several design trade-off studies. Key performance parameters encompassed in the nomogram include receiver losses, intercept factor, engine rating, and engine efficiency. Design and operation parameters such as concentrator size, receiver type (open or windowed aperture), receiver aperture size, operating temperature of the receiver and engine, engine partial load characteristics, concentrator slope error, and the type of reflector surface, are also included in the graphical solution. Cost considerations are not included.

Selcuk, M. K.↗
NASA NTRS1978

Life test results for an ensemble of CO2 lasers

The effects of cathode material, cathode operating temperature, anode configuration, window materials, and hydrogen additives on laser lifetime are determined. Internally oxidized copper and silber-copper alloy cathodes were tested. The cathode operating temperature was raised in some tubes through the use of thermal insulation. Lasers incorporating thermally insulated silver copper oxide cathodes clearly yielded the longest lifetimes-typically in excess of 22,000 hours. The use of platinum sheet versus platinum pin anodes had no observable effect on laser lifetime. Similarly, the choice of germanium, cadmium telluride, or zinc selenide as the optical window material appears to have no impact on lifetime.

Peruso, C. J.↗
NASA NTRS1993

The effects of a dynamic graphical model during simulation-based training of console operation skill

LOADER is a Windows-based simulation of a complex procedural task. The task requires subjects to execute long sequences of console-operation actions (e.g., button presses, switch actuations, dial rotations) to accomplish specific goals. The LOADER interface is a graphical computer-simulated console which controls railroad cars, tracks, and cranes in a fictitious railroad yard. We hypothesized that acquisition of LOADER performance skill would be supported by the representation of a dynamic graphical model linking console actions to goal and goal states in the 'railroad yard'. Twenty-nine subjects were randomly assigned to one of two treatments (i.e., dynamic model or no model). During training, both groups received identical text-based instruction in an instructional-window above the LOADER interface. One group, however, additionally saw a dynamic version of the bird's-eye view of the railroad yard. After training, both groups were tested under identical conditions. They were asked to perform the complete procedure without guidance and without access to either type of railroad yard representation. Results indicate that rather than becoming dependent on the animated rail yard model, subjects in the dynamic model condition apparently internalized the model, as evidenced by their performance after the model was removed.

Farquhar, John D.↗
NASA NTRS2003

Autonomous Mission Manager for Rendezvous, Inspection and Mating

To meet cost and safety objectives, space missions that involve proximity operations between two vehicles require a high level of autonomy to successfully complete their missions. The need for autonomy is primarily driven by the need to conduct complex operations outside of communication windows, and the communication time delays inherent in space missions. Autonomy also supports the goals of both NASA and the DOD to make space operations more routine, and lower operational costs by reducing the requirement for ground personnel. NASA and the DoD have several programs underway that require a much higher level of autonomy for space vehicles. NASA's Space Launch Initiative (SLI) program has ambitious goals of reducing costs by a factor or 10 and improving safety by a factor of 100. DARPA has recently begun its Orbital Express to demonstrate key technologies to make satellite servicing routine. The Air Force's XSS-ll program is developing a protoflight demonstration of an autonomous satellite inspector. A common element in space operations for many NASA and DOD missions is the ability to rendezvous, inspect anclJor dock with another spacecraft. For DARPA, this is required to service or refuel military satellites. For the Air Force, this is required to inspect un-cooperative resident space objects. For NASA, this is needed to meet the primary SLI design reference mission of International Space Station re-supply. A common aspect for each of these programs is an Autonomous Mission Manager that provides highly autonomous planning, execution and monitoring of the rendezvous, inspection and docking operations. This paper provides an overview of the Autonomous Mission Manager (AMM) design being incorporated into many of these technology programs. This AMM provides a highly scalable level of autonomous operations, ranging from automatic execution of ground-derived plans to highly autonomous onboard planning to meet ground developed mission goals. The AMM provides the capability to automatically execute the plans and monitor the system performance. In the event of system dispersions or failures the AMM can modify plans or abort to assure overall system safety. This paper describes the design and functionality of Draper's AMM framework, presents concept of operations associated with the use of the AMM, and outlines the relevant features of the flight demonstrations.

Zimpfer, Douglas J.↗
NASA NTRS1993

HP upgrade operational streamlining

New computer technology and resources must be successfully integrated into CDSLR station operations to manage new complex operational tracking requirements, support the on site production of new data products, support ongoing station performance improvements, and to support new station communication requirements. The NASA CDSLR Network is in the process of upgrading station computer resources with HP UNIX workstations, designed to automate a wide range of operational station requirements. The primary HP upgrade objective was to relocate computer intensive data system tasks from the controller computer to a new advanced computer environment designed to meet the new data system requirements. The HP UNIX environment supports fully automated real time data communications, data management, data processing, and data quality control. Automated data compression procedures are used to improve the efficiency of station data communications. In addition, the UNIX environment supports a number of semi-automated technical and administrative operational station tasks. The x window user interface generates multiple simultaneous color graphics displays, providing direct operator visibility and control over a wide range of operational station functions.

Edge, David R.↗
NASA NTRS1976

Noise limitations of multiplier phototubes in the radiation environment of space

The contributions of Cerenkov emission, luminescence, secondary electron emission, and bremsstrahlung to radiation-induced data current and noise of multiplier phototubes were analyzed quantitatively. Fluorescence and Cerenkov emission in the tube window are the major contributors and can quantitatively account for dark count levels observed in orbit. Radiation-induced noise can be minimized by shielding, tube selection, and mode of operation. Optical decoupling of windows and cathode (side-window tubes) leads to further reduction of radiation-induced dark counts, as does reducing the window thickness and effective cathode area, and selection of window/cathode combinations of low fluorescence efficiency. In trapped radiation-free regions of near-earth orbits and in free space, Cerenkov emission by relativistic particles contributes predominantly to the photoelectron yield per event. Operating multiplier phototubes in the photon (pulse) counting mode will discriminate against these large pulses and substantially reduce the dark count and noise to levels determined by fluorescence.

Viehmann, W.↗
NASA NTRS1974

Skylab program. Earth resources experiment package. Sensor performance report. Volume 7 (S190B): SL2, SL3 and SL4 evaluations

The S190B Earth Terrain Camera (ETC) operated acceptably for all of its scheduled EREP passes throughout the SL2 mission. The crew reported no problems in unstowing the camera, changing filters, installing the ETC window in the SAL, or installing the camera onto the window. The ETC was operated for a total of seven times with no failures. The clock on the ETC was checked on DOY 170 (June 19, 1973) and was found to be 30 min. and 58 sec. slower than GMT. The change in time was expected since a similar circumstance was experienced during ETC qualification testing for launch vibration. A leak existed in the seal of the spare magazine to the camera vacuum interface. For EREP passes 08 and 10, black-and-white film EK 3414 (roll no. 82) was installed in this spare magazine. Since there was an audible hiss, the vacuum hose was not connected to the camera. This caused the vacuum platen to be inoperable, resulting in some degradation in resolution for this roll of film. The vegetation of the South American jungle areas proved to be much darker than vegetation found in the United States, and was consequently about 1/2 stop underexposed in all cases.

Kenney, G. P.↗
NASA NTRS2022

The Puzzling Structure of Solar Convection: Window into the Dynamo

The operation of the solar dynamo, with all of its remarkable spatio-temporal ordering, remains an outstanding problem of modern solar physics. A number of mechanisms that might plausibly contribute to its operation have been proposed, but the relative role played by each remains unclear. This uncertainty stems from continuing questions concerning the speed and structure of deep-seated convective flows. Those flows are in-turn thought to sustain both the Sun’s turbulent EMF and the large-scale flows of differential rotation and meridional circulation suspected of influencing the dynamo’s organization and timing. Ultimately, the convective and large-scale flow structure derive from the Coriolis force. When the Coriolis effect is weak (rapid convective flow), convection exhibits little organization in its spatial structure, and the meridional flow is expected to assume a single-celled profile within each hemisphere. Convection subject to strong Coriolis forces instead organizes into compact, spiraling columnar structures and sustains meridional flows that possess multiple cells in latitude and radius. The implications for the dynamo in these two regimes are substantial, impacting the flux-transport properties of any assumed meridional flow and the convectively-driven EMF. Continued progress in this area is complicated by (i) inconsistencies between helioseismic measurements of convective and meridional flow made with different techniques and instruments, and (ii) a lack of high-latitude data for convection, differential rotation, and meridional flow. We suggest that the path forward to resolving these difficulties is twofold. First, the acquisition of long-term helioseismic and emissivity measurements obtained from a polar vantage point is vital to complete our picture of the Sun’s outer convection zone. Second, sustained and expanded investment in theory-oriented and combined theory/observational research initiatives will be crucial to fully exploit these new observations and to resolve inconsistencies between existing measurements.

SMD↗
NASA NTRS1995

EWB: The Environment WorkBench Version 4.0

The Environment WorkBench EWB is a desktop integrated analysis tool for studying a spacecraft's interactions with its environment. Over 100 environment and analysis models are integrated into the menu-based tool. EWB, which was developed for and under the guidance of the NASA Lewis Research Center, is built atop the Module Integrator and Rule-based Intelligent Analytic Database (MIRIAD) architecture. This allows every module in EWB to communicate information to other modules in a transparent manner from the user's point of view. It removes the tedious and error-prone steps of entering data by hand from one model to another. EWB runs under UNIX operating systems (SGI and SUN workstations) and under MS Windows (3.x, 95, and NT) operating systems. MIRIAD, the unique software that makes up the core of EWB, provides the flexibility to easily modify old models and incorporate new ones as user needs change. The MIRIAD approach separates the computer assisted engineering (CAE) tool into three distinct units: 1) A modern graphical user interface to present information; 2) A data dictionary interpreter to coordinate analysis; and 3) A database for storing system designs and analysis results. The user interface is externally programmable through ASCII data files, which contain the location and type of information to be displayed on the screen. This approach provides great flexibility in tailoring the look and feel of the code to individual user needs. MIRIADbased applications, such as EWB, have utilities for viewing tabulated parametric study data, XY line plots, contour plots, and three-dimensional plots of contour data and system geometries. In addition, a Monte Carlo facility is provided to allow statistical assessments (including uncertainties) in models or data.

Source record↗
NASA NTRS1993

Ultra-high resolution water window x ray microscope optics design and analysis

This project has been focused on the design and analysis of an ultra-high resolution water window soft-x-ray microscope. These activities have been accomplished by completing two tasks contained in the statement of work of this contract. The new results from this work confirm: (1) that in order to achieve resolutions greater than three times the wavelength of the incident radiation, it will be necessary to use spherical mirror surfaces and to use graded multilayer coatings on the secondary in order to accommodate the large variations of the angle of incidence over the secondary when operating the microscope at numerical apertures of 0.35 or greater; (2) that surface contour errors will have a significant effect on the optical performance of the microscope and must be controlled to a peak-to-valley variation of 50-100 A and a frequency of 8 periods over the surface of a mirror; and (3) that tolerance analysis of the spherical Schwarzschild microscope has been shown that the water window operations will require 2-3 times tighter tolerances to achieve a similar performance of operations with 130 A radiation. These results have been included in a manuscript included in the appendix.

Shealy, David L.↗
NASA NTRS2009

Testing Large Structures in the Field

Field testing large structures creates unique challenges such as limited choices for boundary conditions and the fact that natural excitation sources cannot be removed. Several critical developments in field testing of large structures are reviewed, including: step relaxation testing which has been developed into a useful technique to apply large forces to operational systems by careful windowing; the capability of large structures testing with free support conditions which has been expanded by implementing modeling of the support structure; natural excitation which has been developed as a viable approach to field testing; and the hybrid approach which has been developed to allow forces to be estimated in operating structures. These developments have increased the ability to extract information from large structures and are highlighted in this presentation.

James, George↗
NASA NTRS1995

Orbital impacts and the Space Shuttle windshield

The Space Transportation System (STS) fleet has flown more than sixty missions over the fourteen years since its first flight. As a result of encounters with on-orbit particulates (space debris and micrometeoroids), 177 impact features (chips) have been found on the STS outer windows (through STS-65). Forty-five of the damages were large enough to warrant replacement of the window. NASA's orbital operations and vehicle inspection procedures have changes over the history of the shuttle program, in response to concerns about the orbital environment and the cost of maintaining the space shuttle. These programmatic issues will be discussed, including safety concerns, maintenance issues, inspection procedures and flight rule changes. Examples of orbital debris impacts to the shuttle windows will be provided. There will also be a brief discussion of the impact properties of glass and what design changes have been considered to improve the impact properties of the windows.

Edelstein, Karen S.↗