Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “MASS RESOLUTION”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 775 records · Page 43
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Capacitor-type micrometeoroid detectors

The metal oxide semiconductor (MOS) capacitor micrometeroid detector consists of a thin dielectric capacitor fabricated on a silicon wafer. In operation, the device is charged to a voltage level sufficiently near breakdown that micrometeoroid impacts will cause dielectric deformation or heating and subsequent arc-over at the point of impact. Each detector is capable of recording multiple impacts because of the self-healing characteristics of the device. Support instrumentation requirements consist of a voltage source and pulse counters that monitor the pulse of recharging current following every impact. An investigation has been conducted in which 0.5 to 5 micron diameter carbonized iron spheres traveling at velocities of 4 to 10 Km/sec were impacted on to detectors with either a dielectric thickness of 0.4 or 1.0 micron. This study demonstrated that an ion microprobe tuned to sufficiently high resolution can detect Fe remaining on the detector after the impact. Furthermore, it is also possible to resolve Fe ion images free of mass interferences from Si, for example, giving its spatial distribution after impact. Specifically this technique has shown that significant amounts of impacting particles remain in the crater and near it which can be analyzed for isotopic content. Further testing and calibration could lead to quantitive analysis. This study has shown that the capacitor type micrometeroid detector is capable of not only time and flux measurements but can also be used for isotopic analysis.

Wortman, J. J.↗
NASA NTRS1989

No molecular gas disk in S106

The radio and optical bipolar H II region, S106, is bisected by a dark lane. The premain-sequence object, S106 IR, which is the source of a powerful ionized stellar wind, is the exciting source of this region and is found at the center of the equatorial emission gap. The existence of a massive, extended, molecular gas disk has previously been suggested as an explanation for the peculiar morphology of this source, and S106 has widely been quoted as the best example of theoretically posited accretion disks. The new, high-resolution, CS and (C-13)O observations presented show that the molecular emission, previously attributed to a disk structure, actually originates from distinct masses of molecular gas, swept up from the ambient cloud core by the ionized lobes.

Barsony, M.↗
NASA NTRS1989

Solar abundances as derived from solar energetic particles

Recent studies have shown that there are well defined average abundances of heavy (Z above 2) solar energetic particles (SEPs), with variations in the acceleration and propagation producing a systematic flare-to-flare fractionation that depends on the charge per unit mass of the ion. Correcting the average SEP abundances for this fractionation yields SEP-derived coronal abundances for 20 elements. High-resolution SEP studies have also provided isotopic abundances for five elements. SEP-derived abundances indicate that elements with high first ionization potentials (greater than 10 eV) are depleted in the corona relative to the photosphere and provide new information on the solar abundance of C and Ne-22.

Stone, E. C.↗
NASA NTRS2001

Chemical and Isotopic Analysis of Trace Organic Matter on Meteorites and Interstellar Dust Using a Laser Microprobe Instrument

Polycyclic Aromatic Hydrocarbons (PAHs) are of considerable interest today because they are ubiquitous on Earth and in the interstellar medium (ISM). In fact, about 20% of cosmic carbon in the galaxy is estimated to be in the form of PAHs. Investigation of these species has obvious uses for determining the cosmochemistry of the solar system. Work in this laboratory has focused on four main areas: 1) Mapping the spatial distribution of PAHs in a variety of meteoritic samples and comparing this distribution with mineralogical features of the meteorite to determine whether a correlation exists between the two. 2) Developing a method for detection of fullerenes in extraterrestrial samples using microprobe Laser Desorption Ionization Mass Spectroscopy and utilizing this technique to investigate fullerene presence, while exploring the possibility of spatially mapping the fullerene distribution in these samples through in situ detection. 3) Investigating a possible formation pathway for meteoritic and ancient terrestrial kerogen involving the photochemical reactions of PAHs with alkanes under prebiotic and astrophysically relevant conditions. 4) Studying reaction pathways and identifying the photoproducts generated during the photochemical evolution of PAH-containing interstellar ice analogs as part of an ongoing collaboration with researchers at the Astrochemistry Lab at NASA Ames. All areas involve elucidation of the solar system formation and chemistry using microprobe Laser Desorption Laser Ionization Mass Spectrometry. A brief description of microprobe Laser Desorption Ionization Mass Spectroscopy, which allows selective investigation of subattomole levels of organic species on the surface of a sample at 10-40 micrometer spatial resolution, is given.

Zare, Richard N.↗
NASA NTRS2001

Spectroscopy of Low Mass X-Ray Binaries: New Insights into Accretion

This project is to observe two low mass X-ray binaries, chosen for their X-ray brightness, low column density, and diversity of accretion behavior. The high spectral resolution of the RGS, the broad energy range and tremendous collecting power of EPIC, and simultaneous optical monitoring with the OM are particularly well-suited to these studies. observation of one of the two objects has taken place and the data were received in late November. The second object is yet to be observed. Over the next year we will: investigate the physical conditions of the emitting gas using emission and recombination line diagnostics to determine temperatures, densities, elemental abundances, and ionization structure; study the behavior of emission features as a function of binary orbit; and test and improve models of X-ray line emission developed by us over the past decade. We will gain insight on both the geometry of the accretion flow and on the evolutionary history of LMXBs.

DilVrtilek, Saeqa↗
NASA NTRS2001

Airborne Differential Doppler Weather Radar

The Precipitation Radar aboard the Tropical Rain Measuring Mission (TRMM) Satellite has shown the potential for spaceborne sensing of snow and rain by means of an incoherent pulsed radar operating at 13.8 GHz. The primary advantage of radar relative to passive instruments arises from the fact that the radar can image the 3-dimensional structure of storms. As a consequence, the radar data can be used to determine the vertical rain structure, rain type (convective/stratiform) effective storm height, and location of the melting layer. The radar, moreover, can be used to detect snow and improve the estimation of rain rate over land. To move toward spaceborne weather radars that can be deployed routinely as part of an instrument set consisting of passive and active sensors will require the development of less expensive, lighter-weight radars that consume less power. At the same time, the addition of a second frequency and an upgrade to Doppler capability are features that are needed to retrieve information on the characteristics of the drop size distribution, vertical air motion and storm dynamics. One approach to the problem is to use a single broad-band transmitter-receiver and antenna where two narrow-band frequencies are spaced apart by 5% to 10% of the center frequency. Use of Ka-band frequencies (26.5 GHz - 40 GHz) affords two advantages: adequate spatial resolution can be attained with a relatively small antenna and the differential reflectivity and mean Doppler signals are directly related to the median mass diameter of the snow and raindrop size distributions. The differential mean Doppler signal has the additional property that this quantity depends only on that part of the radial speed of the hydrometeors that is drop-size dependent. In principle, the mean and differential mean Doppler from a near-nadir viewing radar can be used to retrieve vertical air motion as well as the total mean radial velocity. In the paper, we present theoretical calculations for the differential reflectivity and Doppler as functions of the center frequency, frequency difference, and median mass diameter. For a fixed pair of frequencies, the detectability of the differential signals can be expressed as the number of independent samples required to detect rain or snow with a particular median mass diameter. Because sampling numbers on the order of 1000 are needed to detect the differential signal over a range of size distributions, the instrument must be confined to a near-nadir, narrow swath. Radar measurements from a zenith directed radar operated at 9.1 GHz and 10 GHz are used to investigate the qualitative characteristics of the differential signals. Disdrometer and rain gauge data taken at the surface, just below the radar, are used to test whether the differential signals can be used to estimate characteristics of the raindrop size distribution.

Meneghini, R.↗
NASA NTRS2002

Spectroscopy of Low Mass X-Ray Binaries: New Insights into Accretion

This project is to observe two low mass X-ray binaries, chosen for their X-ray brightness, low column density, and diversity of accretion behavior. The high spectral resolution of the RGS, the broad energy range and tremendous collecting power of EPIC, and simultaneous optical monitoring with the OM are particularly well-suited to these studies. The second of two objects was not observed until September of 2002. Data analysis for the new observation is underway. over the next year we will: investigate the physical conditions of the emitting gas using emission and recombination line diagnostics to determine temperatures, densities, elemental abundances, and ionization structure; study the behavior of emission features as a function of binary orbit; and test and improve models of X-ray line emission developed by us over the past decade. We will gain insight on both the geometry of the accretion flow and on the evolutionary history of LMXBs.

Vrtilek, Saeqa Dil↗
NASA NTRS2002

Magnetic TRAnsition Region Probe (MTRAP)

MTRAP (Magnetic Transition Region Probe) will reveal the fine-scale physical processes in the Sun's magnetic transition region, the complex layer from the upper photosphere to the upper chromosphere/lower transition region. In the magnetic transition region plasma forces and magnetic forces are of comparable strength, which results in complex interplay of the two, which interplay governs the coupling of the convectively-driven deeper layers to the magnetically-driven upper transition region and inner corona. The fine-scale magnetic structure, processes, and events in the magnetic transition region are key to the genesis of the Sun's entire hot, dynamic outer atmosphere and to the initiation of large eruptive events. MTRAP will be a single spacecraft in Sun-synchronous Earth orbit. Because MTRAP will probe and measure the 3-D structure and dynamics of the magnetic field and plasma in the chromosphere and transition region with unprecedented resolution, the required telescope size and telemetry rates dictate that MTRAP be in Earth orbit, not in deep space. The observations will feature visible and infrared maps of vector magnetic and velocity fields in the magnetic transition region and photosphere. These will have large field of view (greater than 100,000 km), high resolution (greater than 100 km), and high sensitivity (greater than 30 G in transverse field). These observations of the lower atmosphere will be complemented by UV maps of the structure, velocity, and magnetic field (including the full vector field if technically feasible) higher up, in the upper chromosphere and lower transition region. MTRAP will also have an EUV imaging spectrograph observing coronal structure and dynamics in the same field of view with comparable resolution. Specific phenomena to be analyzed include spicules, bright points, jets, the base of plumes, and the triggering of eruptive flares and coronal mass ejections. Additional information is included in the original extended abstract.

Moore, R. L.↗
NASA NTRS2005

Impact of CAMEX-4 Data Sets for Hurricane Forecasts using a Global Model

This study explores the impact on hurricane data assimilation and forecasts from the use of dropsondes and remote-sensed moisture profiles from the airborne Lidar Atmospheric Sensing Experiment (LASE) system. We show that the use of these additional data sets, above those from the conventional world weather watch, has a positive impact on hurricane predictions. The forecast tracks and intensity from the experiments show a marked improvement compared to the control experiment where such data sets were excluded. A study of the moisture budget in these hurricanes showed enhanced evaporation and precipitation over the storm area. This resulted in these data sets making a large impact on the estimate of mass convergence and moisture fluxes, which were much smaller in the control runs. Overall this study points to the importance of high vertical resolution humidity data sets for improved model results. We note that the forecast impact from the moisture profiling data sets for some of the storms is even larger than the impact from the use of dropwindsonde based winds.

Kamineni, Rupa↗
NASA NTRS2009

American Meteorological Society (AMS) - The Modern Era Retrospective-Analysis for Research and Applications (MERRA) Data and Accessibility

The AM Short Course on The Modern Era Retrospective-analysis for Research and Applications (MERRA) data and accessibility will be held on January 11, 2009 preceding the 89th Annual Meeting in Phoenix, Arizona. Preliminary programs, registration, hotel, and general information will be posted on the AMS Web site in mid-September 2008. Retrospective-analyses (or reanalyses) have been established as an important tool in weather and climate research over the last decade. As computer power increases, the data assimilation and modeling systems improve and become more advanced, the input data quality increases and so reanalyses become more reliable. In 2008, NASA Global Modeling and Assimilation Office began producing a new reanalysis called the Modem Era Retrospective-analysis for Research and Applications (MERRA). The initial data from the reanalysis has been made available to the community and should be complete through 30 years (1979-present) by Fall of 2009. MERRA has taken advantage of the advancement of computing resources to provide users more data than previously available. The native spatial resolution is nominally 1/2 degrees and the surface two dimensional data are one hourly frequency. In addition to the meteorological analysis data, complete mass, energy and momentum budget data and also stratospheric data are provided. The eventual data holdings will exceed 150Tb. In order to facilitate user accessibility to the data, it will be stored in online hard drives (not tape storage) and available through several portals. Subsetting tools will also be available to allow users to tailor their data requests. The goals of this short course are to provide hands on users of reanalyses instruction on MERRA systems and also interactive experience with the online data and access tools. The course is intended for students and research scientists who will be actively interested in accessing and applying MERRA data in their weather, climate or applications work. The course has three parts. There will be an overview of the MERRA system, the validation of the system and the native data format. Second, Instructors will provide examples of weather and climate data analysis using various software packages (primarily GrADS) as well as the online access tools for subsetting and download, as well as visualization (e.g. Giovanni and Google Earth). This will also include examples on changing the data format to fit user's preferences and also to regrid the data for comparisons to other reanalyses and observational data. Lastly, there will he time set aside for participants to have hands on access to the data and software while interacting with the instructors and other developers. The course convener is Dr. Michael Bosilovich, NASA GSFC Global Modeling and Assimilation Office (GMAO). He will be joined by several GMAO, Goddard Earth Science Data and information Services Center (GES DISC) and Software Integration and Visualization Office (SIVO) staff.

daSilva, Arlindo↗
NASA NTRS2011

Mission Possible: BioMedical Experiments on the Space Shuttle

Biomedical research, both applied and basic, was conducted on every Shuttle mission from 1981 to 2011. The Space Shuttle Program enabled NASA investigators and researchers from around the world to address fundamental issues concerning living and working effectively in space. Operationally focused occupational health investigations and tests were given priority by the Shuttle crew and Shuttle Program management for the resolution of acute health issues caused by the rigors of spaceflight. The challenges of research on the Shuttle included: limited up and return mass, limited power, limited crew time, and requirements for containment of hazards. The sheer capacity of the Shuttle for crew and equipment was unsurpassed by any other launch and entry vehicle and the Shuttle Program provided more opportunity for human research than any program before or since. To take advantage of this opportunity, life sciences research programs learned how to: streamline the complicated process of integrating experiments aboard the Shuttle, design experiments and hardware within operational constraints, and integrate requirements between different experiments and with operational countermeasures. We learned how to take advantage of commercial-off-the-shelf hardware and developed a hardware certification process with the flexibility to allow for design changes between flights. We learned the importance of end-to-end testing for experiment hardware with humans-in-the-loop. Most importantly, we learned that the Shuttle Program provided an excellent platform for conducting human research and for developing the systems that are now used to optimize research on the International Space Station. This presentation will include a review of the types of experiments and medical tests flown on the Shuttle and the processes that were used to manifest and conduct the experiments. Learning Objective: This paper provides a description of the challenges related to launching and implementing biomedical experiments aboard the Space Shuttle.

Bopp, E.↗
NASA NTRS2012

Development of Metallic Magnetic Calorimeters for High Precision Measurements of Calorimetric Re-187 and Ho-163 Spectra

The measurement of calorimetric spectra following atomic weak decays, beta (b) and electron capture (EC), of nuclides having a very low Q-value, can provide an impressively high sensitivity to a non-vanishing neutrino mass. The achievable sensitivity in this kind of experiments is directly connected to the performance of the used detectors. In particular an energy resolution of a few eV and a pulse formation time well below 1 microsecond are required. Low temperature Metallic Magnetic Calorimeters (MMCs) for soft X-rays have already shown an energy resolution of 2.0 eV FWHM and a pulse rise-time of about 90 ns for fully micro-fabricated detectors. We present the use of MMCs for high precision measurements of calorimetric spectra following the beta-decay of Re-187 and the EC of Ho-163. We show results obtained with detectors optimized for Re-187 and for Ho-163 experiments respectively. While the detectors equipped with superconducting Re absorbers have not yet reached the aimed performance, a first detector prototype with a Au absorber having implanted Ho-163 ions already shows excellent results. An energy resolution of 12 eV FWHM and a rise time of 90 ns were measured.

Ranitzsch, P. C.-O.↗
NASA NTRS2012

A Three Parsec-Scale Jet-Driven Outflow from Sgr A

The compact radio source Sgr A* is coincident with a 4x 10(exp 6) solar Mass black hole at the dynamical center of the Galaxy and is surrounded by dense orbiting ionized and molecular gas. We present high resolution radio continuum images of the central 3' and report a faint continuous linear structure centered on Sgr A*. This feature is rotated by 28 deg in PA with respect to the Galactic plane. A number of weak blobs of radio emission with X-ray counterparts are detected along the axis of the linear structure. In addition, the continuous linear feature appears to be terminated symmetrically by two linearly polarized structures at 8.4 GHz, approx 75" from Sgr A*. The linear structure is best characterized by a mildly relativistic jet-driven outflow from Sgr A*, and an outflow rate 10(exp 6) solar M / yr. The near and far-sides of the jet are interacting with orbiting ionized and molecular gas over the last 1-3 hundred years and are responsible for the origin of a 2" hole, the "minicavity", where disturbed kinematics, enhanced FeII/III line emission, and diffuse X-ray gas have been detected. The estimated kinetic luminosity of the outflow is approx 1.2 X 10(exp 41) erg/s which can produce the Galactic center X-ray flash that has recently been identified

Yusef-Zadeh, F.↗
NASA NTRS2020

Elastic wave analyzer for icy sub-surfaces (EWAIS) in water-bearing worlds

In this paper, we discuss the current status of the development of an elastic wave analyzer for icy sub-surface (EWAIS). We begin with an introductory overview of the necessity to develop an active elastic wave transmitter that will enable reaching distances of kilometer thru ice. It is being developed to be driven by piezoelectric transducers with a bouncing constrained mass that impacts a transmission head. The EWAIS transmits the waves at two distinct frequencies; the primary frequency at ~10 kHz for high resolution, and the secondary converted low frequency (LF) in the range of 100 to 500 Hz for long distance transmission. Sonar equation was used for the estimation of required source level, and an impact force sensor is used for the performance measurement of EWAIS prototype.

Lee, Hyeong Jae↗
NASA NTRS2023

Mercuryʼs Circumsolar Dust Ring as an Imprint of a Recent Impact

A circumsolar dust ring has been recently discovered close to the orbit of Mercury. There are currently no hypotheses for the origin of this ring in the literature, so we explore four different origin scenarios here: the dust originated from (1) the sporadic meteoroid complex that comprises the major portion of the Zodiacal Cloud, (2) recent asteroidal/cometary activity, (3) hypothetical dust-generating bodies locked in mean-motion resonances beyond Mercury, and (4) bodies co-orbiting with Mercury. We find that only scenario (4) reproduces the observed structure and location of Mercury's dust ring. However, the lifetimes of Mercury's co-orbitals (<20 Ma) preclude a primordial origin of the co-orbiting source population due to dynamical instabilities and meteoroid bombardment, demanding a recent event feeding the observed dust ring. We find that an impact on Mercury can eject debris into the co-orbital resonance. We estimate the ages of six candidate impacts that formed craters larger than 40 km in diameter using high-resolution spacecraft data from MESSENGER and find two craters with estimated surface ages younger than 50 Ma. We find that the amount of mass transported from Mercury's surface into the co-orbital resonance from these two impacts is several orders of magnitude smaller than what is needed to explain the magnitude of Mercury's ring inferred from remote sensing. Therefore we suggest that numerous younger, smaller impacts collectively contributed to the origin of the ring. We conclude that the recent impact hypothesis for the origin of Mercury's dust ring is a viable scenario, whose validity can be constrained by future inner solar system missions.

Petr Pokorny↗
NASA NTRS2017

Dynamic Control System Mode Performance of the Space Technology-7 Disturbance Reduction System

The Space Technology-7 (ST-7) Disturbance Reduction System (DRS) is an experiment package aboard the European Space Agency (ESA) LISA Pathfinder spacecraft, launched on December 3, 2015. DRS consists of three primary components: Colloidal MicroNewton Thrusters (CMNTs), an Integrated Avionics Unit (IAU), and flight-software implementing the Command and Data Handling (C&DH) and Dynamic Control System (DCS) algorithms. The CMNTs were designed to provide thrust from 5 to 30 micro Newton, with thrust controllability and resolution of 0.1 micro Newton and thrust noise of 0.1 micro Newton/(square root of (Hz)) in the measurement band from 1-30 mHz. The IAU hosts the C&DH and DCS flight software, as well as interfaces with both the CMNT electronics and the LISA Pathfinder spacecraft. When in control, the DCS uses star tracker attitude data and capacitive or optically-measured position and attitude information from LISA Pathfinder and the LISA Technology Package (LTP) to control the attitude and position of the spacecraft and the two test masses inside the LTP. After completion of the nominal ESA LISA Pathfinder mission, the DRS experiment was commissioned followed by its nominal mission. DRS operations extended over the next five months, interspersed with station keeping, anomaly resolution, and periods where control was handed back to LISA Pathfinder for them to conduct further experiments. The primary DRS mission ended on December 6, 2016, with the experiment meeting all of its Level 1 requirements. The DCS, developed at the NASA Goddard Space Flight Center, consists of five spacecraft control modes and six test mass control modes, combined into six 'DRS Mission Modes'. Attitude Control and Zero-G were primarily used to control the spacecraft during initial handover and during many of the CMNT characterization experiments. The other Mission Modes, Drag Free Low Force, 18-DOF Transitional, and 18-DOF, were used to provide drag-free control of the spacecraft about the test masses. This paper will discuss the performance of these DCS spacecraft and test mass control modes. Flight data will be shown from each mode throughout the mission, both from nominal operations and during various flight experiments. The DCS team also made some changes to controller, filter, and limit parameters during operations; the motivation and results of these changes will be shown and discussed.

O'Donnell, James R., Jr.↗
NASA NTRS2000

Compact Hyperspectral Mapper for Environmental Remote Sensing Applications (CHyMERA) End-of-phase Data Review Package

CHYMERA is an Instrument Incubator concept to design, build, and test an instrument that will reduce size, mass, and cost and increase science potential and flexibility for future atmospheric remote sensing missions within the focus of NASA's Earth Science Enterprise (ESE). The primary effort of the development plan will be on high spatial resolution ozone, N02, S02, aerosol, and cloud measurements, but it is hoped that the techniques developed will prove useful for other measurements as well. The core design will involve a high performance, wide field-of-view (FOV) front end telescope which will illuminate a filter/focal plane array (FFPA) package. The use of a non-dispersive optical configuration will reduce size, mass and complexity. The wide FOV optics will permit short duration global coverage (1-2 days) without the need for a scanner.

Janz, Scott J.↗
NASA NTRS2004

Ultra-Wideband Optical Modulation Spectrometer (OMS) Development

The optical modulation spectrometer (OMS) is a novel, highly efficient, low mass backend for heterodyne receiver systems. Current and future heterodyne receiver systems operating at frequencies up to a few THz require broadband spectrometer backends to achieve spectral resolutions of R approximately 10(exp 5) to 10(exp 6) to carry out many important astronomical investigations. Among these are observations of broad emission and absorption lines from extra-galactic objects at high redshifts, spectral line surveys, and observations of planetary atmospheres. Many of these lines are pressure or velocity broadened with either large half-widths or line wings extending over several GHz. Current backend systems can cover the needed bandwidth only by combining the output of several spectrometers, each with typically up to 1 GHz bandwidth, or by combining several frequency-shifted spectra taken with a single spectrometer. An ultra-wideband optical modulation spectrometer with 10 - 40 GHz bandwidth will enable broadband ob- servations without the limitations and disadvantages of hybrid spectrometers. Spectrometers like the OMS will be important for both ground-based observatories and future space missions like the Single Aperture Far-Infrared Telescope (SAFIR) which might carry IR/submm array heterodyne receiver systems requiring a spectrometer for each array pixel. Small size, low mass and small power consumption are extremely important for space missions. This report summarizes the specifications developed for the OMS and lists already identified commercial parts. The report starts with a review of the principle of operation, then describes the most important components and their specifications which were derived from theory, and finishes with a conclusion and outlook.

Gardner, Jonathan↗