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At least 1,081 records · Page 60

A modular solid state detector for measuring high energy heavy ion fragmentation near the beam axis

A multi-element solid state detector has been designed to measure fluences of fragments produced near the beam axis by high energy heavy ion beams in thick targets. The detector is compact and modular, so as to be readily reconfigured according to the range of fragment charges and energies to be measured. Preamplifier gain settings and detector calibrations are adjustable remotely under computer control. We describe the central detector, its associated detectors and electronics, triggering scheme, data acquisition and particle identification techniques, illustrated by data taken with 600 MeV/u 56Fe beams and thick polyethylene targets at the LBL Bevalac. The applications of this work to space radiation protection are discussed.

NASA Center HQS↗

Compact Two-step Laser Time-of-Flight Mass Spectrometer for in Situ Analyses of Aromatic Organics on Planetary Missions

RATIONALE A miniature time-of-flight mass spectrometer has been adapted to demonstrate two-step laser desorption-ionization (LOI) in a compact instrument package for enhanced organics detection. Two-step LDI decouples the desorption and ionization processes, relative to traditional laser ionization-desorption, in order to produce low-fragmentation conditions for complex organic analytes. Tuning UV ionization laser energy allowed control ofthe degree of fragmentation, which may enable better identification of constituent species. METHODS A reflectron time-of-flight mass spectrometer prototype measuring 20 cm in length was adapted to a two-laser configuration, with IR (1064 nm) desorption followed by UV (266 nm) postionization. A relatively low ion extraction voltage of 5 kV was applied at the sample inlet. Instrument capabilities and performance were demonstrated with analysis of a model polycyclic aromatic hydrocarbon, representing a class of compounds important to the fields of Earth and planetary science. RESULTS L2MS analysis of a model PAH standard, pyrene, has been demonstrated, including parent mass identification and the onset o(tunable fragmentation as a function of ionizing laser energy. Mass resolution m/llm = 380 at full width at half-maximum was achieved which is notable for gas-phase ionization of desorbed neutrals in a highly-compact mass analyzer. CONCLUSIONS Achieving two-step laser mass spectrometry (L2MS) in a highly-miniature instrument enables a powerful approach to the detection and characterization of aromatic organics in remote terrestrial and planetary applications. Tunable detection of parent and fragment ions with high mass resolution, diagnostic of molecular structure, is possible on such a compact L2MS instrument. Selectivity of L2MS against low-mass inorganic salt interferences is a key advantage when working with unprocessed, natural samples, and a mechanism for the observed selectivity is presented.

Getty, Stephanie↗

Development of a Near-Real Time Hail Damage Swath Identification Algorithm for Vegetation

The Midwest is home to one of the world's largest agricultural growing regions. Between the time period of late May through early September, and with irrigation and seasonal rainfall these crops are able to reach their full maturity. Using moderate to high resolution remote sensors, the monitoring of the vegetation can be achieved using the red and near-infrared wavelengths. These wavelengths allow for the calculation of vegetation indices, such as Normalized Difference Vegetation Index (NDVI). The vegetation growth and greenness, in this region, grows and evolves uniformly as the growing season progresses. However one of the biggest threats to Midwest vegetation during the time period is thunderstorms that bring large hail and damaging winds. Hail and wind damage to crops can be very expensive to crop growers and, damage can be spread over long swaths associated with the tracks of the damaging storms. Damage to the vegetation can be apparent in remotely sensed imagery and is visible from space after storms slightly damage the crops, allowing for changes to occur slowly over time as the crops wilt or more readily apparent if the storms strip material from the crops or destroy them completely. Previous work on identifying these hail damage swaths used manual interpretation by the way of moderate and higher resolution satellite imagery. With the development of an automated and near-real time hail swath damage identification algorithm, detection can be improved, and more damage indicators be created in a faster and more efficient way. The automated detection of hail damage swaths will examine short-term, large changes in the vegetation by differencing near-real time eight day NDVI composites and comparing them to post storm imagery from the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard Terra and Aqua and Visible Infrared Imaging Radiometer Suite (VIIRS) aboard Suomi NPP. In addition land surface temperatures from these instruments will be examined as for hail damage swath identification. Initial validation of the automated algorithm is based upon Storm Prediction Center storm reports but also the National Severe Storm Laboratory (NSSL) Maximum Estimated Size Hail (MESH) product. Opportunities for future work are also shown, with focus on expansion of this algorithm with pixel-based image classification techniques for tracking surface changes as a result of severe weather.

Bell, Jordan R.↗

Manned Versus Unmanned Risk and Complexity Considerations for Future Midsized X-Planes

The objective of this work was to identify and estimate complexity and risks associated with the development and testing of new low-cost medium-scale X-plane aircraft primarily focused on air transport operations. Piloting modes that were evaluated for this task were manned, remotely piloted, and unmanned flight research programs. This analysis was conducted early in the data collection period for X-plane concept vehicles before preliminary designs were complete. Over 50 different aircraft and system topics were used to evaluate the three piloting control modes. Expert group evaluations from a diverse set of pilots, engineers, and other experts at Aeronautics Research Mission Directorate centers within the National Aeronautics and Space Administration provided qualitative reasoning on the many issues surrounding the decisions regarding piloting modes. The group evaluations were numerically rated to evaluate each topic quantitatively and were used to provide independent criteria for vehicle complexity and risk. An Edwards Air Force Base instruction document was identified that emerged as a source of the effects found in our qualitative and quantitative data. The study showed that a manned aircraft was the best choice to align with test activities for transport aircraft flight research from a low-complexity and low-risk perspective. The study concluded that a manned aircraft option would minimize the risk and complexity to improve flight-test efficiency and bound the cost of the flight-test portion of the program. Several key findings and discriminators between the three modes are discussed in detail.

x-planes↗

Manned Versus Unmanned Risk and Complexity Considerations for Future Midsized X-Planes

The objective of this work was to identify and estimate complexity and risks associated with the development and testing of new low-cost medium-scale X-plane aircraft primarily focused on air transport operations. Piloting modes that were evaluated for this task were manned, remotely piloted, and unmanned flight research programs. This analysis was conducted early in the data collection period for X-plane concept vehicles before preliminary designs were complete. Over 50 different aircraft and system topics were used to evaluate the three piloting control modes. Expert group evaluations from a diverse set of pilots, engineers, and other experts at Aeronautics Research Mission Directorate centers within the National Aeronautics and Space Administration provided qualitative reasoning on the many issues surrounding the decisions regarding piloting modes. The group evaluations were numerically rated to evaluate each topic quantitatively and were used to provide independent criteria for vehicle complexity and risk. An Edwards Air Force Base instruction document was identified that emerged as a source of the effects found in our qualitative and quantitative data. The study showed that a manned aircraft was the best choice to align with test activities for transport aircraft flight research from a low-complexity and low-risk perspective. The study concluded that a manned aircraft option would minimize the risk and complexity to improve flight-test efficiency and bound the cost of the flight-test portion of the program. Several key findings and discriminators between the three modes are discussed in detail.

quanitive analysis↗

The Bidirectional Reflectance of Black Silicon Used in Space and Earth Remote Sensing Applications

Space-based astrophysical and remote sensing observations often require the detection and measurement of light originating from distant and relatively faint objects. These observations are highly susceptible to scattered light which may introduce imaging artifacts, obscure object details, and increase measurement noise. This paper describes the initial work of characterizing representative black materials used in coronagraph instruments and other spaceborne instruments. Measurements of “blackness” and the achieved reflectance of black silicon are provided in the spectral range from 400nm to 2500nm using 8o directional hemispherical measurements. The bidirectional reflectance of black silicon was also measured at discrete wavelengths, 633nm, and 1064nm, using the optical scatterometer located at NASA Goddard Space Flight Center’s Diffuser Calibration Laboratory (DCL). A 100mm diameter black silicon sample was fabricated and optically characterized. The BRDF of other well-known black materials such as Z306 and Fractal Black are also presented and discussed.

Georgiev, Georgi T.↗

The Bidirectional Reflectance of Black Silicon Used in Space and Earth Remote Sensing Applications

Space-based astrophysical and remote sensing observations often require the detection and measurement of light originating from distant and relatively faint objects. These observations are highly susceptible to scattered light which may introduce imaging artifacts, obscure object details, and increase measurement noise. This paper describes the initial work of characterizing representative black materials used in coronagraph instruments and other spaceborne instruments. Measurements of “blackness” and the achieved reflectance of black silicon are provided in the spectral range from 400nm to 2500nm using 8o directional hemispherical measurements. The bidirectional reflectance of black silicon was also measured at discrete wavelengths, 633nm, and 1064nm, using the optical scatterometer located at NASA Goddard Space Flight Center’s Diffuser Calibration Laboratory (DCL). A 100mm diameter black silicon sample was fabricated and optically characterized. The BRDF of other well-known black materials such as Z306 and Fractal Black are also presented and discussed.

Georgiev, Georgi T.↗

TCL3 UTM (UAS Traffic Management) Flight Tests, Airspace Operations Laboratory (AOL) Report

The Technology Capability Level-3 (TCL3) flight tests were conducted at six different test sites located across the USA from March to May of 2018. The campaign resulted in over 830 data collection flights using 28 different aircraft and involving 20 flight crews. Flights not only varied in duration, but also in the environments and terrains over which they flew. The TCL3 tests highlighted four different types of tests: three tests focused on Communication, Navigation and Surveillance (CNS); six tests focused on Sense and Avoid (SAA) technologies; six tests focused on USS Data and Information Exchange (DAT); and five tests focused on exploring fundamental Concepts of the project (CON). This document presents data collected during the TCL3 tests that informed the operator’s experiences—the quality of the unmanned aerial system (UAS) Service Supplier (USS) information that the operator was provided with, the usefulness of this information, and the usability of the automation, both while airborne and on the ground. It is intended to complement the reports written by the test sites and the quantitative reports and presentations of the UAS Traffic Management (UTM) project. With the goal of instructing what the minimum information requirements and/or best practices might be in TCL3 operations, the driving enquiry was: How do you get the information you need, when you need it, to successfully fly a UAS in UTM airspace? This enquiry touches on two requirements for displays, which are to provide adequate situation awareness (SA) and to share information through a USS. The six test sites participating in the TCL3 tests flew a subset of the 20 tests (outlined above), with most sites working on a subset of each of the four types: Communications, Navigation and Surveillance (CNS); DAT; CON; and Sense and Avoid (SAA). The, mainly qualitative, data addressed in this report was collected by the AOL (Airspace Operations Laboratory) both on-site and remotely for each test. The data consists of the contents of end-of-day debriefs, end-of-day surveys, observer notes, and flight test information, all submitted as part of the Data Management Plan (DMP).

Martin, Lynne↗

Designing and Training for Appropriate Trust in Increasingly Autonomous Advanced Air Mobility Operations: A Mental Model Approach: Version 1

To enable effective human-autonomy teaming (HAT) in Advanced Air Mobility (AAM) operations, the current paper presents a theoretical framework to design and train for appropriate trust in automation. The novel contribution of this work resides in connecting the construct of trust to mental models and showing how this method could be used to enable emerging HAT concepts such as Adaptive Trust Calibration. To contextualize this framework, in section 2 we discuss simplified vehicle operations (SVO) and remote vehicle operations (RVO), which are leading operational concepts within AAM. In section 3 we describe our perspective on automation and increasingly autonomous systems and present a brief discussion on human-automation interaction and human-autonomy teaming. In section 4 we provide a detailed discussion on the construct of trust in automation. In section 5 we present a framework that associates mental models with trust through principles of transparent design. Finally, in section 6 we present three descriptive models for designing and training for appropriate trust in increasingly autonomous systems.

Human-Autonomy Teaming↗

The Precipitation Imaging Package: Assessment of Microphysical and Bulk Characteristics of Snow

Remote-sensing observations are needed to estimate the regional and global impacts of snow. However, to retrieve accurate estimates of snow mass and rate, these observations require augmentation through additional information and assumptions about hydrometeor properties. The Precipitation Imaging Package (PIP) provides information about precipitation characteristics and can be utilized to improve estimates of snowfall rate and accumulation. Here, the goal is to demonstrate the quality and utility of two higher-order PIP-derived products: liquid water equivalent snow rate and an approximation of volume-weighted density called equivalent density. Accuracy of the PIP snow rate and equivalent density is obtained through intercomparison with established retrieval methods and through evaluation with colocated ground-based observations. The results confirm the ability of the PIP-derived products to quantify properties of snow rate and equivalent density, and demonstrate that the PIP produces physically realistic snow characteristics. When compared to the National Weather Service (NWS) snow field measurements of six-hourly accumulation, the PIP-derived accumulations were biased only +2.48% higher. Additionally, this work illustrates fundamentally different microphysical and bulk features of low and high snow-to-liquid ratio events, through assessment of observed particle size distributions, retrieved mass coefficients, and bulk properties. Importantly, this research establishes the role that PIP observations and higher-order products can serve for constraining microphysical assumptions in ground-based and spaceborne remotely sensed snowfall retrievals.

Claire Pettersen↗

Infrared low-level wind shear work

Results of field experiments for the detection of clear air disturbance and low level wind shear utilizing an infrared airborne system are given in vugraph form. The hits, misses and nuisance alarms scores are given. Information is given on the infrared spatial resolution technique. The popular index of aircraft hazard (F= WX over g - VN over AS) is developed for a remote temperature sensor.

Adamson, Pat↗

Using CATS Near-Real-time Lidar Observations to Monitor and Constrain Volcanic Sulfur Dioxide (SO2) Forecasts

An eruption of Italian volcano Mount Etna on 3 December 2015 produced fast-moving sulfur dioxide (SO2) and sulfate aerosol clouds that traveled across Asia and the Pacific Ocean, reaching North America in just 5 days. The Ozone Profiler and Mapping Suite's Nadir Mapping UV spectrometer aboard the U.S. National Polar-orbiting Partnership satellite observed the horizontal transport of the SO2 cloud. Vertical profiles of the colocated volcanic sulfate aerosols were observed between 11.5 and 13.5 km by the new Cloud Aerosol Transport System (CATS) space-based lidar aboard the International Space Station. Backward trajectory analysis estimates the SO2 cloud altitude at 7-12 km. Eulerian model simulations of the SO2 cloud constrained by CATS measurements produced more accurate dispersion patterns compared to those initialized with the back trajectory height estimate. The near-real-time data processing capabilities of CATS are unique, and this work demonstrates the use of these observations to monitor and model volcanic clouds.

space↗

CME Magnetic Structure and IMF Preconditioning Affecting SEP Transport

Coronal mass ejections (CMEs) and solar energetic particles (SEPs) are two manifestations of the various solar phenomena that are known to cause severe space weather effects throughout the heliosphere. The evolution of CMEs after eruption, especially in terms of their magnetic structure, and the configuration of the interplanetary magnetic field (IMF) that influences the transport of SEPs are currently areas of active research. These two aspects are not necessarily independent of each other, especially during solar maximum when multiple eruptive events can occur close in time. Accordingly, we present in this work theanalysis of a CME that erupted from the Sun on 2012 May 11 (SOL2012-05-11) and an SEP event following an eruption that took place on 2012 May 17 (SOL2012-05-17),∼20◦in both latitude and longitude away from the May 11 CME source region. After observing in detailthe eruption and early evolution of the May 11 CME using remote-sensing data from three viewpoints, we evaluate its propagation through interplanetary space using several models.Then, we analyse in-situ measurements from five predicted impact locations (Venus, Earth, the Spitzer Space Telescope, the Mars Science Laboratory en route to Mars, and Mars) in the inner heliosphere in order to search for CME signatures. We find that all five in-situlocations detect signatures of an impulsive SEP event, which we trace back to the May 17 eruption. These findings suggest that the May 11 CME, which was crossing the various locations around the time of the May 17 eruption, provided a direct magnetic connectivityfor the efficient transport of SEPs with an impulsive profile. We discuss the space weather implications of CME evolution, regarding in particular its magnetic structure, and CME-driven IMF preconditioning that facilitates SEP transport from a later event. Finally, this work remarks the importance of the availability of data from multiple spacecraft, even those that do not include space weather research as their primary objective.

Erika Palmerio↗

Application of remote sensing to the geological study of the alkaline complex region of Itatiaia

The methodology of remote sensing applied to geological study in a complex area was evaluated. Itatiaia was selected as a test area, which covers the alkaline massives and its precambrian basement. LANDSAT-MSS and radar mosaic of the RADAMBRASIL Project were used for photointerpretation. Previous geological works were consulted and many discrepancies in the distribution of stratigraphic units were found. Moreover, structural lineaments and talus deposits were clearly delineated.

Dejesusparada, N.↗

Remote sensing of ozone in the middle ultraviolet

Earlier studies of the remote sensing of the ozone distribution from satellites in the middle ultraviolet are extended, giving particular attention to the analytic model method. After a brief introduction, the historical background of this subject is presented. This is followed by a summary and review of early work based upon the analytic model. Then a linearized approach to the problem and a linearized equation for a density correction are discussed. These indicate some of the general limitations of the inversion method. Finally the parametrized model approach is reexamined by using both simulated data and some actual satellite data.

Green, A. E. S.↗

The sensing and perception subsystem of the NASA research telerobot

A useful space telerobot for on-orbit assembly, maintenance, and repair tasks must have a sensing and perception subsystem which can provide the locations, orientations, and velocities of all relevant objects in the work environment. This function must be accomplished with sufficient speed and accuracy to permit effective grappling and manipulation. Appropriate symbolic names must be attached to each object for use by higher-level planning algorithms. Sensor data and inferences must be presented to the remote human operator in a way that is both comprehensible in ensuring safe autonomous operation and useful for direct teleoperation. Research at JPL toward these objectives is described.

Wilcox, B.↗

1998 NASA-ASEE-Stanford Summer Faculty Fellowship Program

This report presents the essential features and highlights of the 1998 Summer Faculty Fellowship Program at Ames Research Center and Dryden Flight Research Center in a comprehensive and concise form. Summary reports describing the fellows' technical accomplishments are enclosed in the attached technical report. The proposal for the 1999 NASA-ASEE-Stanford Summer Faculty Fellowship Program is being submitted under separate cover. Of the 31 participating fellows, 27 were at Ames and 4 were at Dryden. The Program's central feature is the active participation by each fellow in one of the key technical activities currently under way at either the NASA Ames Research Center or the NASA Dryden Flight Research Center. The research topic is carefully chosen in advance to satisfy the criteria of: (1) importance to NASA, (2) high technical level, and (3) a good match to the interests, ability, and experience of the fellow, with the implied possibility of NASA-supported follow-on work at the fellow's home institution. Other features of the Summer Faculty Fellowship Program include participation by the fellows in workshops and seminars at Stanford, the Ames Research Center, and other off-site locations. These enrichment programs take place either directly or remotely, via the Stanford Center for Professional Development, and also involve specific interactions between fellows and Stanford faculty on technical and other academic subjects. A few, brief remarks are in order to summarize the fellows' opinions of the summer program. It is noteworthy that 90% of the fellows gave the NASA-Ames/Dryden- Stanford program an "excellent" rating and the remaining 10%, "good." Also, 100% would recommend the program to their colleagues as an effective means of furthering their professional development as teachers and researchers. Last, but not least, 87% of the fellows stated that a continuing research relationship with their NASA colleagues' organization probably would be maintained. Therefore, the NASA-ASEE- Ames/Dryden-Stanford Program has met its goals very well and every effort will be made to continue to do so in the future.

Source record↗

Sampling Errors in Monthly Rainfall Totals for TRMM and SSM/I, Based on Statistics of Retrieved Rain Rates and Simple Models

Estimates from TRMM satellite data of monthly total rainfall over an area are subject to substantial sampling errors due to the limited number of visits to the area by the satellite during the month. Quantitative comparisons of TRMM averages with data collected by other satellites and by ground-based systems require some estimate of the size of this sampling error. A method of estimating this sampling error based on the actual statistics of the TRMM observations and on some modeling work has been developed. "Sampling error" in TRMM monthly averages is defined here relative to the monthly total a hypothetical satellite permanently stationed above the area would have reported. "Sampling error" therefore includes contributions from the random and systematic errors introduced by the satellite remote sensing system. As part of our long-term goal of providing error estimates for each grid point accessible to the TRMM instruments, sampling error estimates for TRMM based on rain retrievals from TRMM microwave (TMI) data are compared for different times of the year and different oceanic areas (to minimize changes in the statistics due to algorithmic differences over land and ocean). Changes in sampling error estimates due to changes in rain statistics due 1) to evolution of the official algorithms used to process the data, and 2) differences from other remote sensing systems such as the Defense Meteorological Satellite Program (DMSP) Special Sensor Microwave/Imager (SSM/I), are analyzed.

Bell, Thomas L.↗