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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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS2019

Method for Deriving Telescope Specifications for Earth-Detecting Coronagraphs and Its Use in Prioritizing Technology Development Investments

Different potential exoplanet mission concepts require different enabling and enhancing technologies. Decisions regarding prioritizing the development of these technologies can be made using a Science-Driven Systems-Engineering framework. The white paper makes the following specific recommendations. (1) Any potential telescope/coronagraph combination should develop a wavefront stability error budget using the method described in this white paper. That error budget will inform discussions about what technology development will be needed to enable the mission. (2) Enhancing and enabling technologies requiring investment include: low noise reaction wheels or control moment gyros; micro-thruster technology; active vibration isolation; materials and design practice for making lightweight stiff structures and optical components; 200-hertz wavefront sensing and control; 500-hertz sub-picometer-precision edge sensor and position actuators; non-destructive process to quantify CTE (Coefficient of Thermal Expansion) homogeneity of 4-meter class mirrors to an uncertainty of plus or minus 1 parts per billion per degree Kelvin over a 100 by 100 sampling; laser gauge positional metrology system; and predictive active thermal control.

Space Mirror Technology↗
NASA NTRS2004

Tethered Formation Configurations: Meeting the Scientific Objectives of Large Aperture and Interferometric Science

With the success of the Hubble Space Telescope, it has become apparent that new frontiers of science and discovery are made every time an improvement in imaging resolution is made. For the HST working primarily in the visible and near-visible spectrum, this meant designing, building and launching a primary mirror approximately three meters in diameter. Conventional thinking tells us that accomplishing a comparable improvement in resolution at longer wavelengths for Earth and Space Science applications requires a corresponding increase in the size of the primary mirror. For wavelengths in the sub-millimeter range, a very large telescope with an effective aperture in excess of one kilometer in diameter would be needed to obtain high quality angular resolution. Realistically a single aperture this large is practically impossible. Fortunately such large apertures can be constructed synthetically. Possibly as few as three 3 - 4 meter diameter mirrors flying in precision formation could be used to collect light at these longer wavelengths permitting not only very large virtual aperture science to be carried out, but high-resolution interferometry as well. To ensure the longest possible mission duration, a system of tethered spacecraft will be needed to mitigate the need for a great deal of propellant. A spin-stabilized, tethered formation will likely meet these requirements. Several configurations have been proposed which possibly meet the needs of the Space Science community. This paper discusses two of them, weighing the relative pros and cons of each concept. The ultimate goal being to settle on a configuration which combines the best features of structure, tethers and formation flying to meet the ambitious requirements necessary to make future large synthetic aperture and interferometric science missions successful.

Farley, Rodger E.↗
NASA NTRS1983

Registration accuracy and attitude accuracy

Since higher spatial resolution is desired by many applications disciplines coupled with registration in the sub-to-1 pixel range, improved registration accuracy has become necessary. The trend is likely to continue, with image data resolution of 10 meters or less being a routine requirement before the end of this decade. This registration accuracy can only be achieved by the combination of registration and attitude accuracy. This report described the need for improving the attitude accuracy. The relationship between registration accuracy and attitude accuracy is shown, along with criteria for design consideration in establishing adequate attitude accuracy. A precise on-board attitude control system design is essential to provide the attitude accuracy needed to support the subpixel accuracy required for registration of higher resolution images.

Fang, A. C.↗
NASA NTRS1992

Sudbury project (University of Muenster-Ontario Geological Survey): Sr-Nd in heterolithic breccias and gabbroic dikes

One major objective of our Sudbury project was to define origin and age of the huge breccia units below and above the Sudbury Igneous Complex (SIC). The heterolithic Footwall Breccia (FB) represents a part of the uplifted crater floor. It contains subrounded fragments up to several meters in size and lithic fragments with shock features (greater than 10 GPa) embedded into a fine- to medium-grained matrix. Epsilon(sub Nd)-epsilon(sub Sr) relationships point to almost exclusively parautochthonous precursor lithologies. The different textures of the matrix reflect the metamorphic history of the breccia layer; thermal annealing by the overlying hot impact melt sheet (SIC) at temperatures greater than 1000 C resulted in melting of the fine crushed material, followed by an episode of metasomatic K-feldspar growth and, finally, formation of low-grade minerals such as actinolite and chlorite. Isotope relationships in the Onaping breccias (Gray and Green Member) are much more complex. All attempts to date the breccia formation failed: Zircons are entirely derived from country rocks and lack the pronounced Pb loss caused by the heat of the slowly cooling impact melt sheet (SIC). Rb-Sr techniques using either lithic fragments of different shock stages or the thin slab method, set time limits for the apparently pervasive alkali mobility in these suevitic breccias. The data array and the intercept in the plots point to a major Rb-Sr fractionation around 1.54 Ga ago. This model age is in the same range as the age obtained for the metasomatic matrix of the FB. Rb-Sr dating of a shock event in impact-related breccias seems to be possible only if their matrix had suffered total melting by the hot melt sheet (FB) or if they contain a high fraction of impact melt (suevitic Onaping breccias), whereas the degree of shock metamorphism in rock or lithic fragments plays a minor role. In the Sudbury case, however, the impact melt in the seuvitic breccias is devitrified and recrystallized, which changed Rb/Sr ratios quite drastically. Therefore, the Onaping breccias give only age limits for alteration and low-grade metamorphism. The Sm-Nd system was not reset during the Sudbury event; clasts as well as the matrix in the FB and in the Onaping breccias show preimpact 'Archean' Nd isotope signatures.

Buhl, D.↗
NASA NTRS2020

Elastic wave analyzer for icy sub-surfaces (EWAIS) in the solar system

The sub-surface structures of water-bearing icy worlds (e.g., Europa, Enceladus, and Titan) and the structures of icy regions on Mars contain critical information about their origin and evolution. These bodies have been identified as high-priority targets in the NRC Planetary Science Decadal Survey, which noted a lack of technology readiness as one impediment to related missions. An Elastic Wave Analyzer for Icy Sub-surfaces (EWAIS) instrument is being developed to acquire data that can provide answers to fundamental science questions related to these bodies. The EWAIS instrument generates and receives elastic waves using an array of piezoelectric transducers capable of operating at temperatures as low as 30K. A developed breadboard acquires reflected signals from discontinuities in the traveled materials’ impedance (the product of wave velocity and density) along the wave path. Analysis of the acquired data can be used to determine the elastic properties, presence of cracks, locations of cavities and other discontinuities, as well as the thicknesses of ice and liquid layers. The EWAIS instrument is being developed with a novel dual-frequency transmitter array that will enable reaching distances of kilometers through ice, as well as resolving smaller acoustic reflectors nearer the EWAIS instrument. The selected dual frequencies correspond to two depth ranges that can be analyzed, with resolutions of tens of centimeters in the region of tens to hundreds of meters and tens of meters on the kilometers scale, respectively. The EWAIS will be applicable for operation from any in-situ platform, including surface assets (e.g., lander and rover) and sub-surface assets (e.g., melting probes).

Bar-Cohen, Y.↗
NASA NTRS1986

The Io sulfur torus in 1981

A Fabry-Perot spectrometer was used to obtain images of the Io torus in emission lines of S II (wavelength 6716 and 6731) and S III (wavelength 9531) in February and March 1981, on the 2.1 meter telescope at KPNO. The S II and S III images showed a large variation in brightness and radial extent. There is an indication the S II and S III emissions in the warm torus are correlated. The S II and S III emissions in the warm torus also have similar scale heights along the magnetic field lines of approximately 0.6 to 0.72 R sub J. The east-west asymmetry in the S II images taken at similar magnetic longitudes, but 2.5 Jovian rotations apart, supports the theory of convective motions suggested by others. In addition to the images, simultaneous measurements of the S II (6731 wavelength) line profile were also made on one night using a Fabry-Perot scanning spectrometer on the 4 meter at KPNO. The S II spectral scans implied ion temperatures of 52 (+ or - 10) x 10 to the 3rd at 5.2 to 5.6 R sub J from Jupiter and a minimum temperature of at least 3 x 10 to the 5th K at 6 R sub J from Jupiter.

Oliversen, Ronald J.↗
NASA NTRS2018

Quantitative Daily Maps of PM 2.5 Episodes for California and Other Regions: Satellite Column Water and Optical Depth as Allied Tracers of Dilution

The Western US and many regions globally present daunting difficulties in understanding PM 2.5 episodes. We evaluate extensions of a method independent of modeled source-description and transport/transformation and using several satellite remote sensing products from imaging spectrometers. The San Joaquin Valley (SJV) especially suffers few-day episodes due to shallow mixing; PM 2.5 retrieval suffers low satellite AOT (Aerosol Optical Thickness) and bright surfaces.Nevertheless, we find residual errors in our maps of of typically 5-8 micrograms per cubic meter. Episodes in the Valley reaching 60-100 micrograms per cubic meter. These maps detail pollution from Interstate 5 at the scale of a few kilometers. The maps are based on NASA's MODerate resolution Imaging Spectrometer (MODIS) data at circa 1 kilometer as processed with the Multi-Angle Implementation of Atmospheric Correction. The Bay Area Air Quality Management District has requested that we test our methods in their challenging environment characterized by multiple sub-basins defined by complex topography. Our tests suggest that nearly similar precision may be expected for wintertime conditions with high PM 2.5 . We note difficulties when measured PM 2.5 is less than 8-10 micrograms per cubic meter, but good relative precision when PM 2.5 rises above 20; i.e. in episodes of concern for morbidity and mortality. Our method stresses physically meaningful functions of MODIS-MAIAC (Multi-Angle Implementation of Atmospheric Correction)-derived AOD (Aerosol Optical Depth) and total water vapor column. A mixed-effects statistical model exploiting existing station data works powerfully to allow us daily AOT-to-PM 2.5 relationships that allow a calibration of the map. In those cases where water vapor and particles have generally similar surface sources, using the ratio of AOT / Column_water can improve the daily calibrations so as to reach our quoted precision. We briefly present some cartoon idealizations that explain this success and also the likely reasons that our mixed effects model (or "daily calibration") works; also when it should not work. The combined satellite/mixed-effects model works best for wintertime San Joaquin Valley episodes, where the meteorology of particle and H2O(v) dilution is quite appropriate. We extended and tested the methodology (a) for the Bay Area wintertime situations and (b) for smoke plume events (e.g. the October 2017 fire events of the Sonoma area). Our SJV work was evaluated using NASA's DISCOVER-AQ (Deriving Information on Surface conditions from Column and Vertically Resolved Observations Relevant to Air Quality) airborne measurements, and by season- long measurements in Fresno. If the composition and size distribution of the aerosols can be assessed for the regions we describe, retrievals should have improved accuracy.

Chatfield, Robert B.↗
NASA NTRSDate not supplied

Thermoplastic Composite Lunar Tower Truss Structure: Design Development and Verification Plans

The National Aeronautics and Space Administration (NASA) Space Technology and Mission Directorate (STMD) is advancing thermoplastic composite (TPC) technologies for exploration missions. The Technology Development for Exploration Applications (TDEA) project goals are to develop and mature TPC materials, designs, analyses tools and techniques, and mature manufacturing processes. This includes development of manufacturing and joining approaches relevant to space environments. To these ends TDEA endeavors toward demonstrating a TPC truss structure for a lunar tower configuration. The design, predicated on robotic assembly, uses open section truss elements fused to a joint splice plate, without a structural adhesive. This presentation details the TDEA lunar truss structure design development approach including design heritage, the requirements established, the mechanical design and analyses, and thermal analyses demonstrating structural requirements conformance, as well as planned building block verification efforts either underway or planned. The mechanical analyses show the most severe environment is a moon-quake the truss dynamic responses. The thermal analyses show the extreme cold for on-orbit welding, the window for less severe on-orbit welding, as well as the large thermal gradients on the truss. The building block approach shown includes ultrasonic welding and lap shear coupon testing on various truss element thicknesses and layups. Knockdown factor determinations due to lunar dust contamination (simulated) and effects of welding in a vacuum are presented. The most highly loaded truss joint configuration sub-element verification test matrix is outlined. Lastly, plans to build, inspect, and test a 2-bay truss representative unit cell that is 1.5 meters by 1.5 meters by 3.0 meters tall are detailed.

Lunar Tower↗
NASA NTRS1996

Metrology for Spatial Interferometry III

Very high resolution spatial interferometry requires picometer level one-dimensional metrology, surface metrology, and 3-dimensional metrology. The absolute distance measurements with accuracies of only 1 part in a million are required due to the careful design of spacecraft like the proposed Stellar Interferometry Mission (SIM), carrying high resolution stellar interferometers. An absolute calibration system for the surface gauge described in a previous paper is demonstrated. A self-calibrating absolute metrology system with a repeatability of 2 microns rms over a one-way distance of a meter is demonstrated. The accuracy calibration of this gauge is in progress. An auto-aligning, 3-dimensional metrology gauge is constructed using the sub-picometer linear metrology gauge described in earlier papers. Initial test results from this demonstration are presented.

high↗
NASA NTRS1992

ICI optical data storage tape

Optical data storage tape is now a commercial reality. The world's first successful development of a digital optical tape system is complete. This is based on the Creo 1003 optical tape recorder with ICI 1012 write-once optical tape media. Flexible optical media offers many benefits in terms of manufacture; for a given capital investment, continuous, web-coating techniques produce more square meters of media than batch coating. The coated layers consist of a backcoat on the non-active side; on the active side there is a subbing layer, then reflector, dye/polymer, and transparent protective overcoat. All these layers have been tailored for ease of manufacture and specific functional characteristics.

Mclean, Robert A.↗
NASA NTRS2008

Integrated Formation Optical Communication and Estimation System

An architecture has been designed that integrates formation estimation methodologies, precision formation sensing, and high-bandwidth formation communication into a robust, strap-on system that meets knowledge and communication requirements for the majority of planned, precision formation missions. Specifically, the integrated system supports (a) sub-millimeter metrology, (b) multiple greater than 10 Mbps communication channels over a large, 10 deg field-of-view (FOV), and (c) generalized formation estimation methodologies. The sensing sub-system consists of several absolute, metrology gauges with up to 0.1 mm precision that use amplitude-modulated lasers and a LISA-heritage phase meter. Since amplitude modulation is used, inexpensive and robust diode lasers may be used instead of complex, frequency-stabilized lasers such as for nanometer-level metrology. The metrology subsystem laser transceivers consist of a laser diode, collecting optics, and an avalanche photo diode (APD) for detecting incoming laser signals. The APD is necessary since received power is small due to the large (for optical applications) FOV. The phase meter determines the phase of the incoming amplitude modulations as measured by the APD. This phase is equivalent to time-of-flight and, therefore, distance. By placing three laser transceivers on each spacecraft, 18 clock-offset-corrupted distances are calculated. These measurements are communicated and averaged to obtain nine correct distances between the transceivers. From these correct distances, the range and bearing between spacecraft and their relative attitude are determined. Next, communication is integrated on the laser carrier through spectral separation. Metrology amplitude modulations are limited to the 45-50 MHz band, leaving 0-45 MHz for communication. Through careful design of coding scheme, error correction, and filters, six independent 10 Mbps receive channels are possible. Hence, a spacecraft can simultaneously broadcast at 10 Mbps and listen to six other spacecraft. The integrated sensing and communication architecture has been developed, as have formation estimation methodologies that allow the sensing topology to reconfigure as spacecraft maneuver. A bench-top implementation of the integrated sensing and communication architecture is in progress. The final, multiple sensing/communication systems will be tied together via formation estimation algorithms that are also undergoing further development.

Scharf, Daniel↗
NASA NTRS2011

Chlorophyll-a Algorithms for Oligotrophic Oceans: A Novel Approach Based on Three-Band Reflectance Difference

A new empirical algorithm is proposed to estimate surface chlorophyll-a concentrations (Chl) in the global ocean for Chl less than or equal to 0.25 milligrams per cubic meters (approximately 77% of the global ocean area). The algorithm is based on a color index (CI), defined as the difference between remote sensing reflectance (R(sub rs), sr(sup -1) in the green and a reference formed linearly between R(sub rs) in the blue and red. For low Chl waters, in situ data showed a tighter (and therefore better) relationship between CI and Chl than between traditional band-ratios and Chl, which was further validated using global data collected concurrently by ship-borne and SeaWiFS satellite instruments. Model simulations showed that for low Chl waters, compared with the band-ratio algorithm, the CI-based algorithm (CIA) was more tolerant to changes in chlorophyll-specific backscattering coefficient, and performed similarly for different relative contributions of non-phytoplankton absorption. Simulations using existing atmospheric correction approaches further demonstrated that the CIA was much less sensitive than band-ratio algorithms to various errors induced by instrument noise and imperfect atmospheric correction (including sun glint and whitecap corrections). Image and time-series analyses of SeaWiFS and MODIS/Aqua data also showed improved performance in terms of reduced image noise, more coherent spatial and temporal patterns, and consistency between the two sensors. The reduction in noise and other errors is particularly useful to improve the detection of various ocean features such as eddies. Preliminary tests over MERIS and CZCS data indicate that the new approach should be generally applicable to all existing and future ocean color instruments.

Hu, Chuanmin↗
NASA NTRS2016

Characterization of Particulate Matter Profiling and Alveolar Deposition from Biomass Burning in Northern Thailand: The 7-SEAS Study

Biomass burning (BB) frequently occurs in SouthEast Asia (SEA), which significantly affects the air quality and could consequently lead to adverse health effects. The aim of this study was to characterize particulate matter (PM) and black carbon (BC) emitted from BB source regions in SEA and their potential of deposition in the alveolar region of human lungs. A 31-day characterization of PM profiling was conducted at the Doi Ang Khang (DAK) meteorology station in northern Thailand in March 2013. Substantial numbers of PM (10147 +/- 5800 # per cubic centimeter) with a geometric mean diameter (GMD) of 114.4 +/- 9.2 nm were found at the study site. The PM of less than 2.5 micron in aerodynamic diameter (PM sub 2.5) hourly-average mass concentration was 78.0 +/- 34.5 per cubic microgram whereas the black carbon (BC) mass concentration was 4.4 +/- 2.6 micrograms per cubic meter. Notably, high concentrations of nanoparticle surface area (100.5 +/- 54.6 square micrometers per cubic centimeter) emitted from biomass burning can be inhaled into the human alveolar region. Significant correlations with fire counts within different ranges around DAK were found for particle number, the surface area concentration of alveolar deposition, and BC. In conclusion, biomass burning is an important PM source in SEA, particularly nanoparticles, which has high potency to be inhaled into the lung environment and interact with alveolar cells, leading to adverse respiratory effects. The fire counts within 100 to 150 km shows the highest Pearson's r for particle number and surface area concentration. It suggests 12 to 24 hr could be a fair time scale for initial aging process of BB aerosols. Importantly, the people lives in this region could have higher risk for PM exposure.

biomass burning↗
NASA NTRS1973

Spectral structure of tropospheric vertical temperature profiles over Cape Kennedy, Florida.

Recent Jimsphere/Jimsonde measurements of tropospheric temperature profile spectra in the wavelength band from 50 to 2000 meters above the atmospheric boundary layer, taken over Cape Kennedy, Florida, are summarized. The results suggest that the spectra can be represented in the nondimensional form (omega sub g/sigma sub w)phi(k)/sigma sub T squared = S(K), where phi(k) is the temperature profile spectrum at wave number k, omega sub g is the Brunt-Vasala frequency, sigma sub w and sigma sub T denote the standard deviations of the vertical velocity and temperature profiles, and S is a universal function of nondimensional wave number K = k sigma sub w/omega sub g.

Fichtl, G. H.↗
NASA NTRS2011

Bonding Thin Mirror Segments Without Distortion for the International X-Ray Observatory

The International X-Ray Observatory (IXO) uses thin glass optics to maximize large effective area and precise low angular resolution. The thin glass mirror segments must be transferred from their fabricated state to a permanent structure without imparting distortion. IXO will incorporate about fourteen thousand thin mirror segments to achieve the mission goal of 3.0 square meters of effective area at 1.25 keV with an angular resolution of five arcseconds. To preserve figure and alignment, the mirror segment must be bonded with sub-micron movement at each corner. Recent advances in technology development have produced significant x-ray test results of a bonded pair of mirrors. Three specific bonding cycles will be described highlighting the improvements in procedure, temperature control, and precision bonding. This paper will highlight the recent advances in alignment and permanent bonding as well as the results they have produced.

Evans, Tyler C.↗
NASA NTRS2015

Overview and Accomplishments of Advanced Mirror Technology Development Phase 2 (AMTD-2) Project

The Advance Mirror Technology Development (AMTD) project is in Phase 2 of a multiyear effort, initiated in FY12, to mature by at least a half TRL step critical technologies required to enable 4 meter or larger UVOIR space telescope primary mirror assemblies for both general astrophysics and ultra-high contrast observations of exoplanets. AMTD Phase 1 completed all of its goals and accomplished all of its milestones. AMTD Phase 2 started in 2014. Key accomplishments include deriving primary mirror engineering specifications from science requirements; developing integrated modeling tools and using those tools to perform parametric design trades; and demonstrating new mirror technologies via sub-scale fabrication and test. AMTD-1 demonstrated the stacked core technique by making a 43-cm diameter 400 mm thick 'biscuit-cut' of a 4-m class mirror. AMTD-2 is demonstrating lateral scalability of the stacked core method by making a 1.5 meter 1/3rd scale model of a 4-m class mirror.

Space Telescope Mirrors↗
NASA NTRS2000

Mars Exploration with a Self-Refueling Hopper

A small reusable 'hopper' vehicle, the Mars In-situ Propellants Rocket (MIPR), is proposed to fly autonomously on Mars, using in-situ propellant production to manufacture rocket propellant directly out of the Martian atmosphere. The MIPR explores the Martian surface under rocket power and can repeatedly takeoff and land, carrying a suite of science instruments over a range of hundreds of meters per hop. The flight demonstration will accomplish a range of technology objectives important to both unmanned probes and to future human missions, including: (1) demonstration of a sub-orbital Mars launch vehicle, (2) demonstration of a pressure-fed small propulsion system for Mars ascent vehicles, (3) demonstration of a lightweight space engine, and (4) use for the first time of propellants manufactured in-situ on another planetary body. In addition to these technology objectives, the MIPR vehicle can carry a science payload that will advance our understanding of the surface and atmosphere of Mars.

Landis, Geoffrey A.↗
NASA NTRS1992

The 2nd phase of the LEANDRE program: Water-vapor DIAL measurement

As a follow-on of the backscattered lidar, a differential absorption lidar (LEANDRE 2) is now being developed as part of the LEANDRE program for airborne meteorological studies. The primary measurement objective of LEANDRE 2 is water vapor. Pressure and temperature measurements are aimed at a second stage. The goals are to obtain a horizontal resolution of a few hundred meters for a vertical resolution of less than a hundred meters, with an absolute accuracy of 10 percent for humidity measurement. As compatibility is an important feature between the 2 first phases of LEANDRE, most of the LEANDRE 1 sub-system will be used and adapted for LEANDRE 2. For example, detection electronics, central computer, detectors and telescope will be the same. However, important modifications have to be done on the laser source, and spectral control has to be added. Most of the work is thus devoted to those developments, and the status is presented here.

Quaglia, P.↗