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At least 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS2004

Initiating the 2002 Mars Science Laboratory (MSL) Focused Technology Program

The Mars Science Laboratory (MSL) Project is an aggressive mission launching in 2009 to deliver a new generation of rover safely to the surface of Mars and conduct comprehensive in situ investigations using a new generation of instruments. This system will be designed to land with precision and be capable of operating over a large percentage on the surface of Mars. It will have capabilities that will support NASA's scientific goals into the next decade of exphation. The MSL Technology program is developing a wide-range of technologies needed for this Mission and potentially other space missions. The MSL Technology Program reports to both the MSL Project and the Mars Technology Program (MTP). The dual reporting process creates a challenging management situation, but ensures the new technology meets both the specific MSL requirements and the broader Mars Program requirements. MTP is a NASA-wide technology development program managed by the Jet Propulsion Laboratory (JPL) and is divided into a Focused Program and a Base Program. The Focused Technology Program addresses technologies that are specific and critical to near-term missions, while the Base Technology Program addresses those technologies that are applicable to multiple missions and which can be characterized as longer term, higher risk, and high payoff technologies. The MSL Technology Program is under the Focused Program and is tightly coupled to MSL's mission milestones and deliverables. The technology budget is separate from the flight Project budget, but the technology s requirements and the development process are tightly coordinated with the Project. The Technology Program combines proven management techniques of flight projects with commercial and academic technology management strategies, to create a technology management program that meets the near-term requirements of MSL and the long-term requirements of MTP. This paper examines the initiation of 2002 MSL Technology program. Some of the areas discussed in this paper include technology definition, task selection, technology management, and technology assessment.

Caffrey, Robert T.↗
NASA NTRS1993

Characteristics of Ferromagnetic Flux Focusing Lens in the Development of Surface/Subsurface Flaw Detector

Electromagnetic NDE techniques have in the past steered away from the use of ferromagnetic materials. Although their high permeabilities lead to increased field levels, the properties of ferrous elements in the presence of alternating magnetic fields are difficult to determine. In addition, their use leads to losses which can be minimized through the use of low conductivity ferrites. In fact, the eddy current probes which do incorporate ferromagnetic materials have focused on these losses and the shielding which can be obtained by surrounding a probe with a high permeability, conducting material. Eddy current probes enclosed in conducting and magnetic shields have been used to prevent the generated fields from interacting with materials in the vicinity of the probe, such as when testing near material boundaries. A recent invention has used ferromagnetic shielding to magnetically separate individual concentric eddy current probes in order to eliminate cross-talk between the probes so that simultaneous detection of different types of flaws at different depths can be achieved. In contrast to the previous uses of ferromagnetic materials purely as magnetic shields, an electromagnetic flaw detector recently developed at NASA Langley Research Center takes advantage of the flux focusing properties of a ferromagnetic mild steel in order to produce a simple, effective device for the non-destructive evaluation of conducting materials. The Flux Focusing Eddy Current Probe has been shown to accurately measure material thickness and fatigue damage. The straight forward flaw response of the probe makes the device ideal for rapid inspection of large structures, and has lead to its incorporation in a computer controlled search routine to locate fatigue crack tips and monitor experimental fatigue crack growth experiments.

Wincheski, Buzz↗
NASA NTRS2001

High-Frequency Focused Water-Coupled Ultrasound Used for Three-Dimensional Surface Depression Profiling

To interface with other solids, many surfaces are engineered via methods such as plating, coating, and machining to produce a functional surface ensuring successful end products. In addition, subsurface properties such as hardness, residual stress, deformation, chemical composition, and microstructure are often linked to surface characteristics. Surface topography, therefore, contains the signatures of the surface and possibly links to volumetric properties, and as a result serves as a vital link between surface design, manufacturing, and performance. Hence, surface topography can be used to diagnose, monitor, and control fabrication methods. At the NASA Glenn Research Center, the measurement of surface topography is important in developing high-temperature structural materials and for profiling the surface changes of materials during microgravity combustion experiments. A prior study demonstrated that focused air-coupled ultrasound at 1 MHz could profile surfaces with a 25-m depth resolution and a 400-m lateral resolution over a 1.4-mm depth range. In this work, we address the question of whether higher frequency focused water-coupled ultrasound can improve on these specifications. To this end, we employed 10- and 25-MHz focused ultrasonic transducers in the water-coupled mode. The surface profile results seen in this investigation for 25-MHz water-coupled ultrasound, in comparison to those for 1-MHz air-coupled ultrasound, represent an 8 times improvement in depth resolution (3 vs. 25 m seen in practice), an improvement of at least 2 times in lateral resolution (180 vs. 400 m calculated and observed in practice), and an improvement in vertical depth range of 4 times (calculated).

Roth, Don J.↗
NASA NTRS2005

Microfabrication and Test of a Three-Dimensional Polymer Hydro-focusing Unit for Flow Cytometry Applications

This paper details a novel three-dimensional (3D) hydro-focusing micro cell sorter for micro flow cytometry applications. The unit was microfabricated by means of SU-8 3D lithography. The 3D microstructure for coaxial sheathing was designed, microfabricated, and tested. Three-dimensional hydrofocusing capability was demonstrated with an experiment to sort labeled tanned sheep erythrocytes (red blood cells). This polymer hydro-focusing microstructure is easily microfabricated and integrated with other polymer microfluidic structures. Keywords: SU-8, three-dimensional hydro-focusing, microfluidic, microchannel, cytometer

Yang, Ren↗
NASA NTRS2005

Magnetoresistive Flux Focusing Eddy Current Flaw Detection

A giant magnetoresistive flux focusing eddy current device effectively detects deep flaws in thick multilayer conductive materials. The probe uses an excitation coil to induce eddy currents in conducting material perpendicularly oriented to the coil s longitudinal axis. A giant magnetoresistive (GMR) sensor, surrounded by the excitation coil, is used to detect generated fields. Between the excitation coil and GMR sensor is a highly permeable flux focusing lens which magnetically separates the GMR sensor and excitation coil and produces high flux density at the outer edge of the GMR sensor. The use of feedback inside the flux focusing lens enables complete cancellation of the leakage fields at the GMR sensor location and biasing of the GMR sensor to a location of high magnetic field sensitivity. In an alternate embodiment, a permanent magnet is positioned adjacent to the GMR sensor to accomplish the biasing. Experimental results have demonstrated identification of flaws up to 1 cm deep in aluminum alloy structures. To detect deep flaws about circular fasteners or inhomogeneities in thick multi-layer conductive materials, the device is mounted in a hand-held rotating probe assembly that is connected to a computer for system control, data acquisition, processing and storage.

Russell A Wincheski↗
NASA NTRS2006

Inspection of Spray on Foam Insulation (SOFI) Using Microwave and Millimeter Wave Synthetic Aperture Focusing and Holography

The Space Shuttle Columbia s catastrophic failure is thought to have been caused by a dislodged piece of external tank spray on foam insulation (SOFI) striking and significantly damaging the left wing of the orbiter, which may have been due to a flawed section of SOFI. Microwave and millimeter wave nondestructive evaluation (NDE) methods have shown great potential detecting anomalies in SOFI such as small air voids using a horn and lens in a (real) focused configuration. Synthetic focusing methods may also be used to detect air voids in SOFI and may additionally offer the ability to locate the defect in three dimensions. To this end, two different methods were investigated; namely, frequency domain synthetic aperture focusing technique (FD-SAFT) and wide-band microwave holography. To illustrate the performance of these methods they were applied to two different SOFI samples. The results of these investigations demonstrate the capabilities of these methods for SOFI inspection.

Case, J. T.↗
NASA NTRS2006

Overview of High-Resolution Nondestructive Inspection of the Space Shuttle External Tank (ET) Spray-on-Foam Insulation (SOFI) and Acreage Heat tiles using Focused, Synthetic and Holographical Millimeter Wave Techniques

Space Shuttle Columbia's catastrophic failure has been attributed to a piece of spray-on-foam insulation (SOFI) that was dislodged from the external tank (ET) and struck the leading edge of the left wing. A piece of SOFI was also dislodged in the recent Space Shuttle Discovery's flight. From immediately after the Columbia accident, microwave and millimeter wave nondestructive testing methods were considered as potential effective inspection tools for evaluating the integrity of the SOFI. To this end and as a result of these efforts, both real-focused, synthetic focusing and holographical techniques, at a wide range of frequencies covering 24 GHz to 150 GHz, have been developed for this purpose. Images of various complex SOFI panels with a wide range of embedded anomalies (representing real potential defects) have been produced using these techniques, including relatively small anomalies located near complex structural features representative of the external tank. These real-focused and 3D holographical images have effectively demonstrated the utility of these methods for SOFI inspection as being viable, robust, repeatable, simple, portable and relatively inexpensive (tens of $K as opposed to hundreds of $K). In addition, the potential viability of these methods for inspecting acreage heat tiles have has been demonstrated. This paper presents an overview of these activities, representative images of these panels using all of the imaging techniques used and a discussion of the practical attributes of these inspection methods.

Kharkovsky, S.↗
NASA NTRS2006

Focus determination for the James Webb Space Telescope Science Instruments: A Survey of Methods

The James Webb Space Telescope (JWST) is a segmented deployable telescope that will require on-orbit alignment using the Near Infrared Camera as a wavefront sensor. The telescope will be aligned by adjusting seven degrees of freedom on each of 18 primary mirror segments and five degrees of freedom on the secondary mirror to optimize the performance of the telescope and camera at a wavelength of 2 microns. With the completion of these adjustments, the telescope focus is set and the optical performance of each of the other science instruments should then be optimal without making further telescope focus adjustments for each individual instrument. This alignment approach requires confocality of the instruments after integration and alignment to the composite metering structure, which will be verified during instrument level testing at Goddard Space Flight Center with a telescope optical simulator. In this paper, we present the results from a study of several analytical approaches to determine the focus for each instrument. The goal of the study is to compare the accuracies obtained for each method, and to select the most feasible for use during optical testing.

Davila, Pamela S.↗
NASA NTRS2004

Microfabrication and Test of a Three-Dimensional Polymer Hydro-focusing Unit for Flow Cytometry Applications

This paper details a novel three-dimensional (3D) hydro-focusing micro cell sorter for micro flow cytometry applications. The unit was microfabricated by means of SU-8 3D lithography. The 3D microstructure for coaxial sheathing was designed, microfabricated, and tested. Three-dimensional hydro-focusing capability was demonstrated with an experiment to sort labeled tanned sheep erythrocytes (red blood cells). This polymer hydro-focusing microstructure is easily microfabricated and integrated with other polymer microfluidic structures.

Yang, Ren↗
NASA NTRS2005

Magnetoresistive flux focusing eddy current flaw detection

A giant magnetoresistive flux focusing eddy current device effectively detects deep flaws in thick multilayer conductive materials. The probe uses an excitation coil to induce eddy currents in conducting material perpendicularly oriented to the coil's longitudinal axis. A giant magnetoresistive (GMR) sensor, surrounded by the excitation coil, is used to detect generated fields. Between the excitation coil and GMR sensor is a highly permeable flux focusing lens which magnetically separates the GMR sensor and excitation coil and produces high flux density at the outer edge of the GMR sensor. The use of feedback inside the flux focusing lens enables complete cancellation of the leakage fields at the GMR sensor location and biasing of the GMR sensor to a location of high magnetic field sensitivity. In an alternate embodiment, a permanent magnet is positioned adjacent to the GMR sensor to accomplish the biasing. Experimental results have demonstrated identification of flaws up to 1 cm deep in aluminum alloy structures. To detect deep flaws about circular fasteners or inhomogeneities in thick multilayer conductive materials, the device is mounted in a hand-held rotating probe assembly that is connected to a computer for system control, data acquisition, processing and storage.

Wincheski, Russell A.↗
NASA NTRS2006

Gravitational Focusing and the Computation of an Accurate Moon/Mars Cratering Ratio

There have been a number of attempts to use asteroid populations to simultaneously compute cratering rates on the Moon and bodies elsewhere in the Solar System to establish the cratering ratio (e.g., [1],[2]). These works use current asteroid orbit population databases combined with collision rate calculations based on orbit intersections alone. As recent work on meteoroid fluxes [3] have highlighted, however, collision rates alone are insufficient to describe the cratering rates on planetary surfaces - especially planets with stronger gravitational fields than the Moon, such as Earth and Mars. Such calculations also need to include the effects of gravitational focusing, whereby the spatial density of the slower-moving impactors is preferentially "focused" by the gravity of the body. This leads overall to higher fluxes and cratering rates, and is highly dependent on the detailed velocity distributions of the impactors. In this paper, a comprehensive gravitational focusing algorithm originally developed to describe fluxes of interplanetary meteoroids [3] is applied to the collision rates and cratering rates of populations of asteroids and long-period comets to compute better cratering ratios for terrestrial bodies in the Solar System. These results are compared to the calculations of other researchers.

Matney, Mark J.↗
NASA NTRS2008

SWCX Emission from the Helium Focusing Cone - Preliminary Results

Preliminary results from an XMM-Newton campaign to study solar wind charge exchange (SWCX) emission from the heliospheric focusing cone of interstellar helium are presented. The detections of enhanced O VII and O VIII emission from the cone are at the 2(sigma) and 4(sigma) levels. The solar wind charge exchange (SWCX) emission in the heliosphere not associated with distinct objects (e.g., comets and planets including exospheric material in and near Earth s magnetosheath) is proportional to the flux of the solar wind and the space density of neutral material. The neutral material originates in the interstellar medium (ISM) and passes through the solar system due to the relative motion of the Sun and the ISM. The flow of the neutral material through the solar system is strongly perturbed by the Sun both by gravity and by radiation pressure. Because of the relative radiative scattering cross sections and the effect of solar gravitation the density of interstellar hydrogen near the Sun is reduced while interstellar helium is gravitationally focused. This creates a helium focusing cone downstream of the Sun [e.g., 1, and references therein].

Snowden, S. L.↗
NASA NTRS2009

Non-invasive Optical End-to-End Test of a Large TMA Telescope (JWST) from the Intermediate Focus

The James Webb Space Telescope (JWST) requires testing of the full optical system in a cryogenic vacuum environment before launch. Challenges with the telescope architecture and the test environment lead to placing removable optical test sources at the Cassegrain intermediate focus of the Telescope. The Science Instrument suite will be used to align the telescope and to verify the wavefront error. The Science Instruments capture test images that are analyzed using focus diverse phase retrieval. The wavefront sensing algorithms have the large dynamic range required to measure the relatively small wavefronts of interest in the presence of the large aberrations resulting from the off-axis source locations at the intermediate focus. These inherent aberrations of the off-axis design are removed analytically from the measured data. The test design and in-situ wavefront sensing process enables a number of tests to verify the alignment and optical quality of the system.

Whitman, Tony↗
NASA NTRS2011

Focused and Steady-State Characteristics of Shaped Sonic Boom Signatures: Prediction and Analysis

The objective of this study is to examine the effect of flight, at off-design conditions, on the propagated sonic boom pressure signatures of a small "low-boom" supersonic aircraft. The amplification, or focusing, of the low magnitude "shaped" signatures produced by maneuvers such as the accelerations from transonic to supersonic speeds, climbs, turns, pull-up and pushovers is the concern. To analyze these effects, new and/or improved theoretical tools have been developed, in addition to the use of existing methodology. Several shaped signatures are considered in the application of these tools to the study of selected maneuvers and off-design conditions. The results of these applications are reported in this paper as well as the details of the new analytical tools. Finally, the magnitude of the focused boom problem for "low boom" supersonic aircraft designs has been more accurately quantified and potential "mitigations" suggested. In general, "shaped boom" signatures, designed for cruise flight, such as asymmetric and symmetric flat-top and initial-shock ramp waveforms retain their basic shape during transition flight. Complex and asymmetric and symmetric initial shock ramp waveforms provide lower magnitude focus boom levels than N-waves or asymmetric and symmetric flat-top signatures.

Maglieri, Domenic J.↗
NASA NTRS2005

Automatic Focus Adjustment of a Microscope

AUTOFOCUS is a computer program for use in a control system that automatically adjusts the position of an instrument arm that carries a microscope equipped with an electronic camera. In the original intended application of AUTOFOCUS, the imaging microscope would be carried by an exploratory robotic vehicle on a remote planet, but AUTOFOCUS could also be adapted to similar applications on Earth. Initially control software other than AUTOFOCUS brings the microscope to a position above a target to be imaged. Then the instrument arm is moved to lower the microscope toward the target: nominally, the target is approached from a starting distance of 3 cm in 10 steps of 3 mm each. After each step, the image in the camera is subjected to a wavelet transform, which is used to evaluate the texture in the image at multiple scales to determine whether and by how much the microscope is approaching focus. A focus measure is derived from the transform and used to guide the arm to bring the microscope to the focal height. When the analysis reveals that the microscope is in focus, image data are recorded and transmitted.

Huntsberger, Terrance↗
NASA NTRS2011

The Focusing Optics X-Ray Solar Imager: FOXSI

The Focusing Optics x-ray Solar Imager (FOXSI) is a sounding rocket payload funded under the NASA Low Cost Access to Space program to test hard x-ray (HXR) focusing optics and position-sensitive solid state detectors for solar observations. Today's leading solar HXR instrument, the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) provides excellent spatial (2 arcseconds) and spectral (1 keV) resolution. Yet, due to its use of an indirect imaging system, the derived images have a low dynamic range (typically <10) and sensitivity. These limitations make it difficult to study faint x-ray sources in the solar corona which are crucial for understanding the particle acceleration processes which occur there. Grazing-incidence x-ray focusing optics combined with position-sensitive solid state detectors can overcome both of these limitations enabling the next breakthrough in understanding impulsive energy release on the Sun. The FOXSI project is led by the Space Sciences Laboratory at the University of California, Berkeley. The NASA Marshall Space Flight Center is responsible for the grazing-incidence optics, while the Astro-H team at JAXA/ISAS has provided double-sided silicon strip detectors. FOXSI is a pathfinder for the next generation of solar hard x-ray spectroscopic imagers. Such observatories will be able to image the non-thermal electrons within the solar flare acceleration region, trace their paths through the corona, and provide essential quantitative measurements such as energy spectra, density, and energy content in accelerated electrons.

Krucker, Saem↗
NASA NTRS2019

Understanding the Impact of Meteorological Spatiotemporal Variability on Distant Focusing Overpressure Risk

Since the 1950s, the amplification of blast energy from explosions has been understood to be a significant hazard to public safety at launch ranges. Historically, the risk assessment of the Distant Focusing Overpressure (DFO) hazard started with a single temperature and wind profile (e.g., a radiosonde launch) as input to acoustic 1-D ray tracing models. By analyzing rays propagation and performing ray tracing, population centers under high DFO risk can be identified. Although this method is useful, less is known about how the blast waves can be focused when the spatiotemporal variability of the input profiles are considered. In summary, this work aims to consider how realistic atmospheric boundary layer variability (e.g., turbulence, land-surface contrasts) may affect blast waves propagation and focusing and, as a result, DFO risk assessment results.

Blumberg, W. Greg↗
NASA NTRSDate not supplied

Realistic gravitational focusing of meteoroid streams

A meteor shower can be modeled, to first order, as a parallel stream of particles encountering the Earth. Gravity bends the trajectories of these particles inward, producing an increase in flux both near the planet and along the anti-radiant line. This effect is known as gravitational focusing, and the interception of a portion of meteoroid trajectories by the Earth or another massive body is known as planetary shielding. For a perfectly parallel meteoroid stream, gravitational focusing produces a flux singularity along the anti-radiant line, near which intense enhancements in flux occur. In reality, meteoroids will exhibit some dispersion in their motion that removes this singularity. We present a modified analytic treatment of gravitational focusing and planetary shielding that takes this dispersion into account and discuss its ramifications for several problems in meteor astronomy.

Althea Valkyrie Moorhead↗