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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 361 records · Page 20
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Summary of the nondestructive evaluation session

Advanced material systems and designs require improved nondestructive evaluation (NDE) techniques for quality control, failure analysis and properties monitoring. Some advanced NDE techniques such as infrared scanning systems, laser holographic applications and the use of the Mossbauer effect are outlined. Applications of these techniques are discussed for evaluating the new space shuttle external insulation materials, aircraft structures and engine components, and precursors to crack initiation and growth.

Stinebring, R. C.↗
NASA NTRS1975

A 10.6 micron ladar for space rendezvous and docking

The paper describes a 10.6 micron ladar (a laser detection and ranging device) which is considered as a baseline sensor for space rendezvous and docking applications. The sensor uses a passively Q-switched CO2 laser as the transmitter active element, and a four-quadrant photodiode array, operated as a coherent receiver element in the heterodyne mode. The aperture will be about 3 inches, and the telescope will be able to steer the beam in a 40 by 40 degree window. Various aspects of the ladar system are examined in detail, including the laser control loop, the transmitter, the local oscillator, the telescope, and the output beam scanning.

Lowrey, D. O.↗
NASA NTRS1980

Control and dynamics study for the satellite power system. Volume 1: MPTS/SPS collector dynamic analysis and surface deformation

The basic dynamic properties and performance characteristics of the microwave power transmission satellite antenna were analyzed in an effort to develop criteria, requirements, and constraints for the control and structure design. The vibrational properties, the surface deformation, and the corresponding scan loss under the influence of disturbances are considered.

Wang, S. J.↗
NASA NTRS1980

The remote-controlled spectrograph, area scanner, and spectropolarimeter for the Lick 3-m telescope

A Cassegrain spectrograph used in conjunction with an image-tube, image-dissector scanner (ITS) is discussed with reference to its design features and operation. The spectrograph has a remote control feature, and its parameters, such as slit width, decker position, filter selection, focus, and grating selection, can be easily changed by computer command or a hard-wired control box. The discussion also includes the area scanner modification which allows raster scanning and limited picture taking. Finally, the design of a two-channel polarization analyzer is presented which allows simultaneous sky and sky-plus-star observations and faint-object polarimetry.

Miller, J. S.↗
NASA NTRS1980

Geometrical rectification of spin-scan images from Pioneer 11

Images of Saturn received from Pioneer 11 suffer from geometrical distortions due to the curvilinear scan lines and the unequal sampling intervals in orthogonal directions, which are inherent in spin-scan imaging. In this paper geometrical image rectification by polynomial transformation based on control points is discussed. Factors that affect the accuracy of reconstruction are shown to include the spatial distribution and spatial density of control points, and the order of the polynomial distortion model. A computer implementation of the technique is described.

Strickland, R. N.↗
NASA NTRS1981

A new method for focusing and imaging X-rays and gamma-rays with diffraction crystals

Bent diffraction crystals in which the intercrystalline-plane spacing is varied as a function of position in the crystal are used to focus monochromatic radiation from a point source or parallel beam down to a point image. Conversely, radiation from a point source can be focused into an outgoing parallel beam. The Bragg angle for diffraction of monochromatic radiation will now vary as a function of position in the crystal and this new degree of freedom is used to obtain focusing and imaging of the diffracted beam. This approach to focusing and imaging is applied to the design of a large-area, high resolution X-ray telescope that is also a high resolution monochromator with the unique feature that the width of the energy increment that is diffracted can be controlled and varied during the operation of the instrument. The field can be scanned with a wide energy increment and then switched to a narrow energy increment for the high resolution work. Both transmission and reflection type diffraction crystals can be used.

Smither, R. K.↗
NASA NTRS1989

The X-ray Timing Explorer Mission

The technical aspects of the X-ray Timing Explorer (XTE) mission are described with particular attention paid to the current scientific problems it will address. It features a low-background, continuous 2-200 keV response with large areas. Rapid response (in hours) to observing opportunities is obtained by virtue of a scanning all-sky monitor, rapid spacecraft maneuverability, and rapid response in the control center. XTE will carry out detailed, energy-resolved studies of phenomena close to neutron stars and black holes utilizing XTE's submillisecond timing, its high telemetry rates, and the high throughput of its data system.

Rothschild, Richard E.↗
NASA NTRS1992

Applications of industrial engineering

Two separate and distinctly different projects are described within this paper: the stepping motion bearing tester, and the memo search and find project. The objective of the first project was to program the JSI Digital Servo Controller to control the motor using the stepping pattern prescribed by the AMSU-U2 Scan Profile. The objective of the second project was to develop a dBASE 3 Plus program that would allow the user to gain the necessary information to retrieve the memo(s) being sought upon supplying a word or group of words possibly found in the keyword list or upon supplying the author's name.

Yarbrough, Walthea V.↗
NASA NTRS1996

Feedback Linearization in a Six Degree-of-Freedom MAG-LEV Stage

A six degree-of-freedom electromagnetically suspended motion control stage (the Angstrom Stage) has been designed and constructed for use in short-travel, high-resolution motion control applications. It achieves better than 0.5 nm resolution over a 100 micron range of travel. The stage consists of a single moving element (the platen) floating in an oil filled chamber. The oil is crucial to the stage's operation since it forms squeeze film dampers between the platen and the frame. Twelve electromagnetic actuators provide the forces necessary to suspend and servo the platen, and six capacitance probes measure its position relative to the frame. The system is controlled using a digital signal processing board residing in a '486 based PC. This digital controller implements a feedback linearization algorithm in real-time to account for nonlinearities in both the magnetic actuators and the fluid film dampers. The feedback linearization technique reduces a highly nonlinear plant with coupling between the degrees of freedom into one that is linear, decoupled, and setpoint independent. The key to this procedure is a detailed plant model. The operation of the feedback linearization procedure is transparent to the outer loop of the controller, and so a proportional controller is sufficient for normal operation. We envision applications of this stage in scanned probe microscopy and for integrated circuit measurement.

Ludwick, Stephen J.↗
NASA NTRS2002

A Large Aperture Fabry-Perot Tunable Filter Based On Micro Opto Electromechanical Systems Technology

A research and development effort sponsored by the NASA Goddard Spaceflight Center (GSFC) is focused on applying Micro Opto Electromechanical Systems (MOEMS) technology to create a miniature Fabry-Perot tunable etalon for space and ground-based near infrared imaging spectrometer applications. Unlike previous devices developed for small-aperture telecommunications systems, the GSFC research is directed toward a novel 12 - 40 mm aperture for astrophysical studies, including emission line imaging of galaxies and nebulae, and multi-spectral redshift surveys in the 1.1 - 2.3 micron wavelength region. The MOEMS design features integrated electrostatic scanning of the 11-micron optical gap, and capacitance micrometry for closed loop control of parallelism within a 10-nm tolerance. The low thermal mass and inertia inherent in MOEMS devices allows for rapid cooling to the proposed 30 K operating temperature, and high frequency response. Achieving the proposed 6-nm aperture flatness (with an effective finesse of 50) represents the primary technical challenge in the current 12-mm prototype.

Greenhouse, Matt↗
NASA NTRS2005

A back-illuminated megapixel CMOS image sensor

In this paper, we present the test and characterization results for a back-illuminated megapixel CMOS imager. The imager pixel consists of a standard junction photodiode coupled to a three transistor-per-pixel switched source-follower readout [1]. The imager also consists of integrated timing and control and bias generation circuits, and provides analog output. The analog column-scan circuits were implemented in such a way that the imager could be configured to run in off-chip correlated double-sampling (CDS) mode. The imager was originally designed for normal front-illuminated operation, and was fabricated in a commercially available 0.5 pn triple-metal CMOS-imager compatible process. For backside illumination, the imager was thinned by etching away the substrate was etched away in a post-fabrication processing step.

Complementary Metal Oxide Semiconductor imager (CM↗
NASA NTRS2014

Evaluation of RTM370 Polyimide Composites by Resin Film Infusion (RFI)

RTM370 imide oligomer based on 2,3,3',4'-biphenyl dianhydride (a-BPDA), 3,4'-oxydianiline (3,4'-ODA) and terminated with the 4-phenylethynylphthalic (PEPA) endcap has been shown to exhibit a low melt viscosity (10-30 poise) at 280 C with a pot-life of 1-2 h and a high cured glass-transition temperature (Tg) of 370 C. RTM370 resin has been successfully infused into fiberglass-stitched T650-35 carbon-fabric preforms (ranged from 3- to 6-mm thick) by resin film infusion (RFI). The resulting composite panels were inspected by ultrasonic C-scan and by photomicrographs before and after post-curing as a quality control. Mechanical tests such as unnotched compression (UNC), open-hole compression (OHC), and short-beam shear strength (SBS) at ambient and elevated temperatures were performed before and after isothermal aging at 288 C for 1000 h to assess high-temperature performance. Thermal cycling of RTM370 stitched composites was also conducted from -54 C to 288 C for up to 1600 cycles to evaluate the microcrack resistance of RTM370 polyimide composites fabricated by RFI.

Polyimide↗
NASA NTRS2003

The development of inflatable array antennas

The deployable array antenna using an inflatable or thin-membrane structure has been identified as one of the enabling technologies to achieve low-mass, high packaging efficiency, low cost, and reliable deployment for future NASNJPL spacebome high-gain and large aperture antennas. Array antennas, when compared to parabolic reflectors, although suffering from limited bandwidth performance, offer wide-angle beam scanning capability and a more reliable flat “natural” aperture. To demonstrate the feasibility and capability of this low-mass array technology, three antenna concepts using inflatable and thin-membrane structures were initiated in 1997 at JPL and several breadboard units have been successfully developed. These three concepts are (1) the inflatable phased array, (2) the inflatable reflectarray, and (3) frame-supported thin membrane array antenna. All three concepts utilize the printed microstrip antenna technology. Although all three concepts will be briefly presented, this paper will discuss in more detail of the recent development of the second concept. The first concept of inflatable phased arrays that have been constructed are 3 to 5-meter size L-band dual-polarized synthetic aperture radar (SAR) arrays for Earth remote sensing application. They all consist of a rectangular configuration with inflatable cylindrical tubes that support and tension a multi-layer thin-membrane radiating aperture with microstrip patches and microstrip power divider lines. For the second concept, an inflatable reflectarray was developed for future deep-space telecom applications. It is a 3m Ka-band inflatable reflectarray (1.8 kg/m2). This reflectarray uses inflated torus tubes to support and tension a flat-membrane reflectarray surface. The reflectarray surface emulates a curved parabolic reflecting surface. However, because of its flat surface being a “natural surface”, it is much easier to achieve and more reliable to maintain the required surface tolerance than that of a curved parabola during long space flight. For the third concept, an L-band dual polarized SAR array with a 5m x 3m aperture and 2.5 kg/m2 of mass has recently been demonstrated. It consists of seven foldable panels each having a rectangular frame that supports a two-layer thinmembrane microstrip subarray aperture. Each frame is made of light-weight graphite composite material. The chief advantage of this deployable “frame” concept is that each frame is able to rigidly support an appropriate number of T/R modules and phase shifters to achieve the desired power distribution and beam scanning. Several technology challenges, such as the development of rigidizable inflatable tubes, a controlled deployment mechanism, thin-membrane thermal effects, a low-mass inflation system, membrane mounted T/R modules, means to counter surface tolerance issues, etc. are being investigated and will be discussed in the presentation. With foreseeable success in the development of these challenging areas, the inflatable/thin-membrane array antennas could be mature enough in a few years for actual space flight.

Lou, Michael↗
NASA NTRS1976

Flight evaluation of advanced navigation techniques for general aviation using frequency scanning

Experiments on an automatic multisensor navigation concept are being conducted in a Cessna 402B. The test system consists of VOR, DME, and air data sensors controlled by a Hewlett Packard 9820A electronic calculator which processes the data and, by means of a four-state Kalman filter, outputs position and ground and wind velocities to a map display. Novel features which make such a system potentially low-cost include frequency-scanning operation of a single VOR receiver and a single DME transceiver and use of a shed-vortex true airspeed sensor. Results obtained during flight in a local area where six to eight DME NAVAIDS were receivable yielded better than 1/4-mile accuracy.

Jackson, C. T., Jr.↗
NASA NTRS1981

Simultaneous in-flight calibrations of the Galileo science platform and attitude control subsystems

This paper presents a design metholodology and simulation study results for a combined star scanner-gyro-scan platform in-flight calibration for the dual spin Galileo spacecraft. The design process involves three separate parts: the construction of an error model, development of the calibration model, and the selection of the appropriate estimation technique. The major innovative contribution lies in the development of the first two parts which are unique to the Galileo design. A unified procedure has been developed to allow simultaneous calibration of the three subsystems. However, provisions are also made in the software to calibrate each subsystem separately when the necessary a priori information is available.

Lai, J. Y.↗
NASA NTRS1979

Fabrication of structural elements

The laminate fabrication procedures and quality assurance ultrasonic C-scan results used for structural elements are described. These procedures are the result of processing eleven lots of graphite/PMR-15 prepreg tape materials and two lots of graphite/NR-150B2. Early processing difficulties with NR-150B2 composites were corrected, permitting the fabrication of quality specimens from either of the two currently prescribed matrix materials. The quality of all deliverable specimens is measured by the control of fiber content, glass transition temperature, and void content, as well as laminate ultrasonic C-scan data.

Darms, F. J., Jr.↗
NASA NTRS2018

Robotic External Leak Locator (RELL) Leak Plume Field Detection on the International Space Station (ISS)

The Robotic External Leak Locator (RELL) was deployed to the International Space Station (ISS) with the objective of demonstrating the ability to detect and locate small leaks. On-orbit operations began in late November 2016 and following scanning activities to characterize the natural and induced environment of the ISS, RELL focused on the United States External Active Thermal Control System (EATCS). RELL successfully detected ammonia related to a known small ammonia leak in the port-side EATCS, with the highest pressure values around the inboard Radiator Beam Valve Module 1 (RBVM 1). An additional day of scanning was subsequently performed in December 2017 to focus on RBVM 1. RELL was approved for additional external operations in February 2017 with the goal of fine tuning the location of the leak. Using grid scanning patterns, RELL detected ammonia around RBVM 1 and located the approximate source of the leak. The potential leak site was inspected by a crew member during an Extravehicular Activity (EVA) in March 2017, and the suspected radiator-side lines were isolated from the port-side EATCS coolant loop in April 2017. Subsequent monitoring of the system pressures showed that the leak has stopped, indicating RELL accurately located the source of the EATCS leak. These activities verify that RELL enhances the ISS Program's ability to not only locate small leaks, but isolate the source with minimal impact to the entire ISS system.

External Active Thermal Control System↗
NASA NTRS2002

Segmented mirror coarse phasing with white light interferometry: modeling and experiment on NGST's wavefront control testbed

A method of coarse phasing segmented mirrors using white light interferometry (WLI) has been developed for Next Generation Space Telescope (NGST) wavefront sensing and control. Using the broadband point spread function (PSF) of the segmented mirrors taken during a segment piston scan, the WLI can accurately detect small residual piston errors. WLI does not rely on any extra optics and uses only the final imaging camera. With its high sensitivity to small segment piston error WLI can be used as a complementary phasing algorithm to the dispersed fringe sensor (DFS) for NGST. The paper will present the results from modeling and experiment on the NGST's Wavefront Control Testbed (WCT).

Space↗