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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 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
NASA NTRS1995

15 cut-off 128x128 Quantum Well Infrared Photodetectors (QWIPS) Camera

We discuss the development and the performance of a very long wavelength (13.5 - 15 128x128 AlGaAs/GaAs multiquantum well infrared imaging system. Highly uniform, high-yield QWIP focal plane array was hybridized to a CMOS multiplexer operating in a direct injection mode. For efficient light coupling an integral random scattering reflector (Random Grating) was incorporated. Due to the high uniformity, excellent imagery, low noise as well as a noise equivalent temperature difference (NE T) of less than 30 mK were obtained when operating around 45 K. Therefore, high image contrast signal to noise ratio has been achieved.

128x128 Photodetectors↗
NASA NTRS2005

The Effects of Instrumental Elliptical Polarization on Stellar Point Spread Function Fine Structure

We present procedures and preliminary results from a study on the effects of instrumental polarization on the fine structure of the stellar point spread function (PSF). These effects are important to understand because the the aberration caused by instrumental polarization on an otherwise diffraction-limited will likely have have severe consequences for extreme high contrast imaging systems such as NASA's planned Terrestrial Planet Finder (TPF) mission and the proposed NASA Eclipse mission. The report here, describing our efforts to examine these effects, includes two parts: 1) a numerical analysis of the effect of metallic reflection, with some polarization-specific retardation, on a spherical wavefront; 2) an experimental approach for observing this effect, along with some preliminary laboratory results. While the experimental phase of this study requires more fine-tuning to produce meaningful results, the numerical analysis indicates that the inclusion of polarization-specific phase effects (retardation) results in a point spread function (PSF) aberration more severe than the amplitude (reflectivity) effects previously recorded in the literature.

high angular resolution↗
NASA NTRS2006

Polarization Phase-Compensating Coats for Metallic Mirrors

A method of compensating for or minimizing phase differences between orthogonal polarizations of light reflected from metallic mirrors at oblique incidence, as, for example, from weakly curved mirrors, is undergoing development. The method is intended to satisfy a need to maintain precise polarization phase relationships or minimum polarization differences needed for proper operation of telescopes and other scientific instruments that include single or multiple mirrors. The basic idea of the method is to optimally coat mirrors with thin engineered layers of materials that introduce phase differences that, as nearly precisely as possible, are opposite of the undesired phase differences arising in reflection with non-optimum coatings. Depending on the specific optical system, the method could involve any or all of the following elements: a) Optimization of a single coat on all the mirrors in the system. b) Optimization of a unique coat for each mirror such that the polarization phase effects of the coat on one mirror compensate, to an acceptably high degree over an acceptably wide wavelength range, for those of the coat on another mirror. c) Tapering the coat on each mirror. Optimization could involve the choice of a single dielectric coating material and its thickness, or design of a more complex coat consisting of multiple layers of different dielectric materials and possibly some metallic materials. Such designs and coatings are particularly significant and needed for obtaining very high quality of wavefront required in high-contrast imaging instruments such as the NASA Terrestrial Planet Finder Coronagraph.

Balasubramanian, Kunjithapatham↗
NASA NTRS2010

The Astrophysics Science Division Annual Report 2009

The Astrophysics Science Division (ASD) at Goddard Space Flight Center (GSFC) is one of the largest and most diverse astrophysical organizations in the world, with activities spanning a broad range of topics in theory, observation, and mission and technology development. Scientific research is carried out over the entire electromagnetic spectrum - from gamma rays to radio wavelengths - as well as particle physics and gravitational radiation. Members of ASD also provide the scientific operations for three orbiting astrophysics missions - WMAP, RXTE, and Swift, as well as the Science Support Center for the Fermi Gamma-ray Space Telescope. A number of key technologies for future missions are also under development in the Division, including X-ray mirrors, space-based interferometry, high contrast imaging techniques to search for exoplanets, and new detectors operating at gamma-ray, X-ray, ultraviolet, infrared, and radio wavelengths. The overriding goals of ASD are to carry out cutting-edge scientific research, provide Project Scientist support for spaceflight missions, implement the goals of the NASA Strategic Plan, serve and support the astronomical community, and enable future missions by conceiving new concepts and inventing new technologies.

Oegerle, William↗
NASA NTRS2010

Visible Nulling Coronagraphy Testbed Development for Exoplanet Detection

Three of the recently completed NASA Astrophysics Strategic Mission Concept (ASMC) studies addressed the feasibility of using a Visible Nulling Coronagraph (VNC) as the prime instrument for exoplanet science. The VNC approach is one of the few approaches that works with filled, segmented and sparse or diluted aperture telescope systems and thus spans the space of potential ASMC exoplanet missions. NASA/Goddard Space Flight Center (GSFC) has a well-established effort to develop VNC technologies and has developed an incremental sequence of VNC testbeds to advance the this approach and the technologies associated with it. Herein we report on the continued development of the vacuum Visible Nulling Coronagraph testbed (VNT). The VNT is an ultra-stable vibration isolated testbed that operates under high bandwidth closed-loop control within a vacuum chamber. It will be used to achieve an incremental sequence of three visible light nulling milestones of sequentially higher contrasts of 10(exp 8) , 10(exp 9) and 10(exp 10) at an inner working angle of 2*lambda/D and ultimately culminate in spectrally broadband (>20%) high contrast imaging. Each of the milestones, one per year, is traceable to one or more of the ASMC studies. The VNT uses a modified Mach-Zehnder nulling interferometer, modified with a modified "W" configuration to accommodate a hex-packed MEMS based deformable mirror, a coherent fiber bundle and achromatic phase shifters. Discussed will be the optical configuration laboratory results, critical technologies and the null sensing and control approach.

Lyon, Richard G.↗
NASA NTRS2011

Machine Vision for Relative Spacecraft Navigation During Approach to Docking

This paper describes a machine vision system for relative spacecraft navigation during the terminal phase of approach to docking that: 1) matches high contrast image features of the target vehicle, as seen by a camera that is bore-sighted to the docking adapter on the chase vehicle, to the corresponding features in a 3d model of the docking adapter on the target vehicle and 2) is robust to on-orbit lighting. An implementation is provided for the case of the Space Shuttle Orbiter docking to the International Space Station (ISS) with quantitative test results using a full scale, medium fidelity mock-up of the ISS docking adapter mounted on a 6-DOF motion platform at the NASA Marshall Spaceflight Center Flight Robotics Laboratory and qualitative test results using recorded video from the Orbiter Docking System Camera (ODSC) during multiple orbiter to ISS docking missions. The Natural Feature Image Registration (NFIR) system consists of two modules: 1) Tracking which tracks the target object from image to image and estimates the position and orientation (pose) of the docking camera relative to the target object and 2) Acquisition which recognizes the target object if it is in the docking camera Field-of-View and provides an approximate pose that is used to initialize tracking. Detected image edges are matched to the 3d model edges whose predicted location, based on the pose estimate and its first time derivative from the previous frame, is closest to the detected edge1 . Mismatches are eliminated using a rigid motion constraint. The remaining 2d image to 3d model matches are used to make a least squares estimate of the change in relative pose from the previous image to the current image. The changes in position and in attitude are used as data for two Kalman filters whose outputs are smoothed estimate of position and velocity plus attitude and attitude rate that are then used to predict the location of the 3d model features in the next image.

Chien, Chiun-Hong↗
NASA NTRS2011

Exoplanetary Science: Instrumentation, Observations, and Expectations

More than 700 exoplanets have been discovered and studied using indirect techniques, leading our field into the exciting new era of comparative exoplanetology. However, the direct detection of exoplanetary systems still remains at the sensitivity limits of both ground- and space-based observatories. The development of new technologies for adaptive optics systems and high contrast instruments continues to increase the ability to directly study exoplanets. The scientific impact of these developments has promising prospects for both short and long timescales. In my talk, I will discuss recent highlights from the SEEDS survey and the current instrumentation in use at the Subaru telescope. SEEDS is a high contrast imaging strategic observing program with 120 nights of time allocated at the NAOJ's flagship optical and infrared telescope. I will also describe new instrumentation I designed to improve the SEEDS capabilities and efficiency. Finally, I will briefly discuss the conceptual design of a transiting planet camera to fly as a potential second generation instrument on-board NASA's SOFIA observatory.

McElwain, Michael↗
NASA NTRS2012

Transmission Electron Microscopy of Single Wall Carbon Nanotube/Polymer Nanocomposites: A First-Principles Study

The physics of HRTEM image formation and electron diffraction of SWCNT in a polymer matrix were investigated theoretically on the basis of the multislice method, and the optics of a FEG Super TWIN Philips CM 200 TEM operated at 80 kV. The effect of nanocomposite thickness on both image contrast and typical electron diffraction reflections of nanofillers were explored. The implications of the results on the experimental applicability to study dispersion, chirality and diameter of nanofillers are discussed.

Sola, Francisco↗
NASA NTRS2014

Modeling the X-Ray Process, and X-Ray Flaw Size Parameter for POD Studies

Nondestructive evaluation (NDE) method reliability can be determined by a statistical flaw detection study called probability of detection (POD) study. In many instances the NDE flaw detectability is given as a flaw size such as crack length. The flaw is either a crack or behaving like a crack in terms of affecting the structural integrity of the material. An alternate approach is to use a more complex flaw size parameter. The X-ray flaw size parameter, given here, takes into account many setup and geometric factors. The flaw size parameter relates to X-ray image contrast and is intended to have a monotonic correlation with the POD. Some factors such as set-up parameters including X-ray energy, exposure, detector sensitivity, and material type that are not accounted for in the flaw size parameter may be accounted for in the technique calibration and controlled to meet certain quality requirements. The proposed flaw size parameter and the computer application described here give an alternate approach to conduct the POD studies. Results of the POD study can be applied to reliably detect small flaws through better assessment of effect of interaction between various geometric parameters on the flaw detectability. Moreover, a contrast simulation algorithm for a simple part-source-detector geometry using calibration data is also provided for the POD estimation.

Khoshti, Ajay↗
NASA NTRS2014

Modeling the X-ray Process, and X-ray Flaw Size Parameter for POD Studies

Nondestructive evaluation (NDE) method reliability can be determined by a statistical flaw detection study called probability of detection (POD) study. In many instances, the NDE flaw detectability is given as a flaw size such as crack length. The flaw is either a crack or behaving like a crack in terms of affecting the structural integrity of the material. An alternate approach is to use a more complex flaw size parameter. The X-ray flaw size parameter, given here, takes into account many setup and geometric factors. The flaw size parameter relates to X-ray image contrast and is intended to have a monotonic correlation with the POD. Some factors such as set-up parameters, including X-ray energy, exposure, detector sensitivity, and material type that are not accounted for in the flaw size parameter may be accounted for in the technique calibration and controlled to meet certain quality requirements. The proposed flaw size parameter and the computer application described here give an alternate approach to conduct the POD studies. Results of the POD study can be applied to reliably detect small flaws through better assessment of effect of interaction between various geometric parameters on the flaw detectability. Moreover, a contrast simulation algorithm for a simple part-source-detector geometry using calibration data is also provided for the POD estimation.

Koshti, Ajay M.↗
NASA NTRS2013

Tomographic Sounding of Protoplanetary and Transitional Disks: Using Inner Disk Variability at Near to Mid-IR Wavelengths to Probe Conditions in the Outer Disk

Spitzer synoptic monitoring of young stellar associations has demonstrated that variability among young stars and their disks is ubiquitous. The Spitzer studies have been limited by target visibility windows and cover only a short temporal baseline in years. A complementary approach is to focus on stars chosen for high-value observations (e.g. high-contrast imaging, interferometry, or access to wavelengths which are difficult to achieve from the ground) where the synoptic data can augment the imagery or interferometry as well as probing disk structure. In this talk, we discuss how synoptic data for two protoplanetary disks, MWC 480 and HD 163296, constrain the dust disk scale height, account for variable disk illumination, and can be used to locate emission features, such as the IR bands commonly associated with PAHs in the disk, as part of our SOFIA cycle 1 study. Similar variability is now known for several pre-transitional disks, where synoptic data can be used to identify inner disks which are not coplanar with the outer disk, and which may be relicts of giant planet-giant planet scattering events. Despite the logistical difficulties in arranging supporting, coordinated observations in tandem with high-value observations, such data have allowed us to place imagery in context, constrained structures in inner disks not accessible to direct imagery, and may be a tool for identifying systems where planet scattering events have occurred.

target visibility windows↗
NASA NTRS2014

Goddard's Astrophysics Science Division Annual Report 2013

The Astrophysics Science Division (ASD) at Goddard Space Flight Center (GSFC) is one of the largest and most diverse astrophysical organizations in the world, with activities spanning a broad range of topics in theory, observation, and mission and technology development. Scientific research is carried out over the entire electromagnetic spectrum from gamma rays to radio wavelengths as well as particle physics and gravitational radiation. Members of ASD also provide the scientific operations for two orbiting astrophysics missions Fermi Gamma-ray Space Telescope and Swift as well as the Science Support Center for Fermi. A number of key technologies for future missions are also under development in the Division, including X-ray mirrors, space-based interferometry, high contrast imaging techniques to search for exoplanets, and new detectors operating at gamma-ray, X-ray, ultraviolet, infrared, and radio wavelengths. The overriding goals of ASD are to carry out cutting-edge scientific research, provide Project Scientist support for spaceflight missions, implement the goals of the NASA Strategic Plan, serve and support the astronomical community, and enable future missions by conceiving new concepts and inventing new technologies.

ultraviolet astrophysics↗
NASA NTRS2013

Estimate Low and High Order Wavefront Using P1640 Calibrator Measurements

P1640 high contrast imaging system on the Palomar 200 inch Telescope consists of an apodized-pupil Lyot coronagraph, the PALM-3000 adaptive optics (P3K-AO), and P1640 Calibrator (CAL). Science images are recorded by an integral field spectrograph covering J-H bands for detecting and characterizing stellar companions. With aberrations from atmosphere corrected by the P3K-AO, instrument performance is limited mainly by the quasi-static speckles due to noncommon path wavefront aberrations for the light to propagate to the P3K-AO wavefront sensor and to the coronagraph mask. The non-common path wavefront aberrations are sensed by CAL, which measures the post-coronagraph E-field using interferometry, and can be effectively corrected by offsetting the P3K-AO deformable mirror target position accordingly. Previously, we have demonstrated using CAL measurements to correct high order wavefront aberrations, which is directly connected to the static speckles in the image plane. Low order wavefront, on the other hand, usually of larger amplitudes, causes light to leak through the coronagraph making the whole image plane brighter. Knowledge error in low order wavefront aberrations can also affect the estimation of the high order wavefront. Even though, CAL is designed to sense efficiently high order wavefront aberrations, the low order wavefront front can be inferred with less sensitivity. Here, we describe our method for estimating both low and high order wavefront aberrations using CAL measurements by propagating the post-coronagraph E-field to a pupil before the coronagraph. We present the results from applying this method to both simulated and experiment data.

aberrations↗
NASA NTRS2010

The JWST/NIRCam Coronagraph Flight Occulters

The NIRCam instrument on the James Webb Space Telescope will have a Lyot coronagraph for high contrast imaging of extrasolar planets and circumstellar disks at lambda = 2 - 5 micrometers. Half-tone patterns are used to create graded-transmission image plane masks. These are generated using electron beam lithography and reactive ion etching of a metal layer on an antireflection coated sapphire substrate. We report here on the manufacture and evaluation of the flight occulters.

extrasolar planets↗
NASA NTRS2017

A New Method of Absorption-Phase Nanotomography for 3D Observation of Mineral-Organic-Water Textiles and its Application to Pristine Carbonaceous Chondrites

Pristine carbonaceous chondrites contain fine-grained matrix, which is composed largely of amorphous silicates, sub-micron silicate and sulfide crystals, and organic materials. They are regarded as primitive dust in the early Solar System that have suffered minimal alteration in their parent bodies. The matrix generally has different lithologies; some of them are unaltered but some are more or less aqueously altered. Their textures have been examined in 2D usually by FE-SEM/EDS, TEM/EDS, nano-SIMS and micro-XRD. Observation of their complex fine textures, such as spatial relation between different lithologies in 3D, is important for understanding aggregation and alteration processes. Synchrotron radiation (SR)-based X-ray tomography reveals 3D structures nondestructively with high spatial resolution of approximately greater than 100 nm. We have developed a new technique using absorption contrasts called "dual-energy tomography" (DET) to obtain 3D distribution of minerals at SPring-8, SR facility in Japan, and applied successfully to Itokawa particles. Phase and absorption contrast images can be simultaneously obtained in 3D by using "scanning-imaging x-ray microscopy" (SIXM) at SPring-8, which can discriminate between void, water and organic materials. We applied this technique combined with FIB micro-sampling to carbonaceous chondrites to search for primitive liquid water. In this study, we combined the DET and SIXM to obtain three dimensional submicron-scale association between minerals, organic materials and water and applied this to pristine carbonaceous chondrites.

Tsuchiyama, A.↗
NASA NTRS2016

A Substellar Companion to Pleiades HII 3441

We find a new substellar companion to the Pleiades member star, Pleiades HII 3441, using the Subaru telescope with adaptive optics. The discovery is made as part of the high-contrast imaging survey to search for planetary-mass and substellar companions in the Pleiades and young moving groups. The companion has a projected separation of 0". 49+/-0". 02 (66+/-2 au) and a mass of 68+/-5M(sub J) based on three observations in the J-, H-, and K(sub s)-bands. The spectral type is estimated to be M7 (approx. 2700 K), and thus no methane absorption is detected in the H band. Our Pleiades observations result in the detection of two substellar companions including one previously reported among 20 observed Pleiades stars, and indicate that the fraction of substellar companions in the Pleiades is about 10.0+26.1 −8.8 %. This is consistent with multiplicity studies of both the Pleiades stars and other open clusters.

Pleiades HII 3441↗
NASA NTRS2017

Synergies of Subaru and CGI

Given the limited observing time and demanding scenarios of the WFIRST coronagraph instrument (CGI), it is critical to consider how Subaru observations can benefit its observing program. Subaru telescope has a suite of instruments with their adaptive optics (AO) and extreme adaptive optics modules (SCExAO). With SCExAO, the Subaru telescope is capable of detection and spectral characterization of binaries and bright (greater than 5(exp -6) contrast) companions in the near-infrared. This will enable the vetting of targets, disk detection and characterization, and potentially some additional science should CGI identify interesting targets during its technology demonstration and potential guest observer program. Additionally, large companions that are within the inner working angle of the coronagraph can be identified using the VAMPIRES aperture masking interferometer. With highly complementary target brightness and significantly overlapping fields of view, there is a great deal of potential for combined observations with Subaru and CGI. This will represent the first time single observations spanning the visible to near-infrared will be possible for high contrast imaging. We will discuss the overlap of instrumentation over time, the implication of instrument evolution as TMT comes online, and how this can be used to improve both science and technology demonstrations for CGI.

adaptive optics (AO↗
NASA NTRS2017

The Evolution of the Deformation Substructure in a Ni-Co-Cr Equiatomic Solid Solution Alloy

The equiatomic NiCoCr alloy exhibits an excellent combination of strength and ductility, even greater than the FeNiCrCoMn high entropy alloy, and also displays a simultaneous increase in strength and ductility with decreasing the testing temperature. To systemically investigate the origin of the exceptional properties of NiCoCr alloy, which are related to the evolution of the deformation substructure with strain, interrupted tensile testing was conducted on the equiatomic NiCoCr single-phase solid solution alloy at both cryogenic and room temperatures at five different plastic strain levels of 1.5%, 6.5%, 29%, 50% and 70%. The evolution of deformation substructure was examined using electron backscatter diffraction (EBSD), transmission Kikuchi diffraction (TKD), conventional transmission electron microscopy (CTEM), diffraction contrast imaging using STEM (DCI-STEM) and atomic resolution scanning transmission electron microscopy. While the deformation substructure mainly consisted of planar dislocation slip and the dissociation of dislocations into stacking faults at small strain levels (≤6.5%), at larger strain levels, additional substructures including nanotwins and a new phase with hexagonal close packed (HCP) lamellae also appeared. The volume fraction of the HCP lamellae increases with increasing deformation, especially at cryogenic temperature. First principles calculations at 0 K indicate that the HCP phase is indeed energetically favorable relative to FCC for this composition. The effects of the nanotwin and HCP lamellar structures on hardening rate and ductility at both cryogenic and room temperature are qualitatively discussed.

Twinning↗