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At least 1,315 records · Page 73

Gravity Poppers: Hopping Probes for the Internal Mapping of Small Solar System Bodies

This paper presents the results of NIAC Phase I study into the feasibility of a novel mission architecture for highresolution gravity science on small Solar System bodies. The “Gravity Poppers” mission concept (see Fig. 1) consists of a swarm of small, minimalistic probes that are deployed from a mother spacecraft to the surface of a small body and which periodically and randomly hop around the surface. By tracking the ballistic sub-orbital trajectories of this hopping swarm, a very high resolution gravity field can be measured, which can then be used to answer a number of scientific questions of interest regarding the interior mass distribution of the body. This paper describes the three core focus areas of our study to demonstrate concept feasibility: (1) the design of hopping probes to be small, simple, robust, and “visible” to a distant spacecraft, (2) the tracking strategy for detecting and estimating the trajectories of a large number of ballistic probes, and (3) the algorithmic framework by which such measurements can be used to estimate the body’s gravity field. Our results suggest the ability to estimate the gravity field of a 500m asteroid beyond degree-and-order 40 through days to weeks of optical tracking of several LED-strobing probes, with a mass of only 200 g each. Collectively, this study demonstrates that the high-resolution gravity mapping of small body interiors is technically possible, economically feasible, and would enable a compelling set of science objectives aligned with NASA’s goals in planetary science, planetary defense, and future interests in resource prospecting.

McMahon, Jay↗

Analysis Insights: The Key Role Analysis Plays in R&D

Over the last two decades, the National Renewable Energy Laboratory (NREL) has been applying its analytical expertise to help guide and advance renewable energy technology research and development (R&D). Working shoulder-to-shoulder with world-class researchers - at NREL, other national laboratories, and universities - and industry partners, NREL analysts continue to search for answers to emerging energy challenges every day. Our objective methodologies and tools are now helping stakeholders assess and prioritize R&D efforts as fast as new innovative technologies transition from concept to commercial application. Throughout that journey, NREL's analyses highlight key technical barriers, compare tradeoffs among proposed technology development pathways, track progress toward performance and cost targets, and illuminate the impacts of proposed innovations. This edition of NREL's Analysis Insights takes a deeper look at the role analysis has played in guiding renewable energy innovation at our laboratory, and beyond. In doing so, the report substantiates what we have known for 20 years - that informed analyses must remain at the leading edge of future R&D efforts.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

Innovative Data Management System in Support of Remedial Actions for Legacy Radioactive Contamination - 17280

The Port Hope Area Initiative (PHAI) is a project mandated and funded by the Government of Canada to remove contamination from properties with legacy low-level radioactive waste (LLRW) contamination arising from a crown-owned radium and, later, uranium refinery in the Town of Port Hope, Ontario. From 1976 to 1981, a community clean-up project was undertaken, with the specific purpose to decrease the level of historic LLRW contamination within Port Hope. Since then, residual LLRW has been managed by the Low Level Radioactive Waste Management Office (LLRWMO) (and its predecessors). The PHAI and the Port Hope Project (PHP) were initiated in 2001 with a formal agreement between affected municipalities and the federal government to develop a safe, long-term management solution for the historic LLRW remaining within Port Hope. An important activity of the PHP is the survey of about 4,800 'small scale sites' (SSS) throughout the community to confirm the presence or absence of LLRW. This involves surveys of properties based on the measurement of exterior gamma, contaminated objects and surfaces, soil concentrations and indoor radon and classification to Port Hope project specific criteria. A very large amount of information is involved in the project including; scheduling individual field visits to the properties, capture of field data and comments, laboratory sample tracking, QA/QC, report generation and internal and client project reporting at regular schedules. Field data collection of exterior gamma radiation surveys includes direct (real time) and interactive loading of data into the Information Management (IM) system to support initial QA/QC and reporting back to the field on radiation levels. Screening soil measurements including X-ray fluorescence (XRF) and gamma radiation are collected from all 20 cm increments in each borehole in addition to down-hole gamma radiation measurements and logging of soil characteristics which are used in documentation and interpretation of the property condition. The IM system outlined in this paper was developed to respond to the requirements for radiological surveys in Port Hope. The IM system continues to evolve as a part of continuing review and improvement. The IM system incorporates Web-enabled field tools and cloud hosted data and applications, provides increased field efficiency, timeliness in reporting, real time QA/QC analysis, and consistency in tracking project advances and changes made to the data for decision-making and reporting on an ongoing basis. Examples of specific applications are provided. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Atmospheric Modeling to Enable Prediction of Golden Eagle Interactions with Wind Power Plants

This panel will explore the use of technologies and methods that enhance our understanding of eagle behavior in and near wind energy facilities. The decreasing costs of tracking technologies and substantial computational capabilities are allowing for finer resolution and confidence of eagle observations and the modeling of such datasets increase our understanding of their movements and use of airspace and underlying landscapes. Behavior ecologists' intrinsic knowledge of eagle behavior can augment and further enhance inferences from technology-derived information alone, e.g., GPS, camera, radar, etc. The panel will discuss the state of science and, given the cost-effective tools available, what research objectives are emerging to better assess and reduce wind-eagle risk. The discussion will focus on the following areas: Integrating Behavioral and Quantitative Ecologist perspectives of bald eagle and golden eagle behavior and wind energy risk; Regional-scale vs. facility-scale investigations of bald eagle and golden eagle use of airspace. For example, avoidance behavior to assess risk at facility-scale, and eagle use of landscapes, e.g., territories, nesting, and life-cycle behavior; Bald eagle and golden eagle use of airspace and nexus with atmospheric flow dynamics of wind energy generation; GPS, biomonitoring, tracking camera, radar, and other tools/techniques for deepening the knowledge of eagle behavior in and around wind farms.

49 EE - Wind and Water Power Program - Wind (EE-4W↗

Cooperative Collision Avoidance Step 1 - Technology Demonstration Flight Test Report. Revision 1

The National Aeronautics and Space Administration (NASA) Access 5 Project Office sponsored a cooperative collision avoidance flight demonstration program for unmanned aircraft systems (UAS). This flight test was accomplished between September 21st and September 27th 2005 from the Mojave Airport, Mojave, California. The objective of these flights was to collect data for the Access 5 Cooperative Collision Avoidance (CCA) Work Package simulation effort, i.e., to gather data under select conditions to allow validation of the CCA simulation. Subsequent simulation to be verified were: Demonstrate the ability to detect cooperative traffic and provide situational awareness to the ROA pilot; Demonstrate the ability to track the detected cooperative traffic and provide position information to the ROA pilot; Demonstrate the ability to determine collision potential with detected cooperative traffic and provide notification to the ROA pilot; Demonstrate that the CCA subsystem provides information in sufficient time for the ROA pilot to initiate an evasive maneuver to avoid collision; Demonstrate an evasive maneuver that avoids collision with the threat aircraft; and lastly, Demonstrate the ability to assess the adequacy of the maneuver and determine that the collision potential has been avoided. The Scaled Composites, LLC Proteus Optionally Piloted Vehicle (OPV) was chosen as the test platform. Proteus was manned by two on-board pilots but was also capable of being controlled from an Air Vehicle Control Station (AVCS) located on the ground. For this demonstration, Proteus was equipped with cooperative collision sensors and the required hardware and software to place the data on the downlink. Prior to the flight phase, a detailed set of flight test scenarios were developed to address the flight test objectives. Two cooperative collision avoidance sensors were utilized for detecting aircraft in the evaluation: Traffic Alert and Collision Avoidance System-II (TCAS-II) and Automatic Dependent Surveillance Broadcast (ADS-B). A single intruder aircraft was used during all the flight testing, a NASA Gulfstream III (G-III). During the course of the testing, six geometrically different near-collision scenarios were evaluated. These six scenarios were each tested using various combinations of sensors and collision avoidance software. Of the 54 planned test points 49 were accomplished successfully. Proteus flew a total of 21.5 hours during the testing and the G-III flew 19.8 hours. The testing fully achieved all flight test objectives. The Flight IPT performed an analysis to determine the accuracy of the simulation model used to predict the location of the host aircraft downstream during an avoidance maneuver. The data collected by this flight program was delivered to the Access 5 Cooperative Collision Avoidance (CCA) Work Package Team who was responsible for reporting on their analysis of this flight data.

Trongale, Nicholas A.↗

Haffner 16 Redux: Revisiting a Young Cluster in the Outer Galaxy

Images and spectra recorded with the Gemini Multi-Object Spectrograph on Gemini South are used to investigate the stellar content of the open cluster Haffner 16. The (i{sup ′},g{sup ′}−i{sup ′}) color–magnitude diagram (CMD) constructed from these data extends over 10 mag in i{sup ′}, sampling the cluster main sequence (MS) and 5 mag of the pre-MS (PMS). The fraction of unresolved equal mass binaries among PMS stars is estimated to be 0.6 ± 0.1. The isochrones do not track the PMS on the CMD, in the sense that the PMS has a shallower slope on the CMD than predicted by the models. Still, a dip in star counts, which is associated with the relaxation of PMS stars onto the MS, is identified near i{sup ′}=17. The depth and brightness of this feature—as well as the morphology of the cluster MS on the CMD—are matched by models with a slightly sub-solar metallicity that have an age of ∼20 Myr and a distance modulus of 12.3 ± 0.2. A light profile of Haffner 16 is constructed in the W1 filter (λ{sub cen}=3.4 μm), which suggests that the cluster is surrounded by a diffuse stellar halo. Spectra of candidate cluster MS and PMS stars selected according to location on the CMD are presented. The spectra show characteristics that are suggestive of a sub-solar metallicity. Hα emission is common among objects on the PMS locus on the CMD near i{sup ′}=18. It is suggested that the location of the Haffner 16 PMS on the CMD is affected by large-scale cool spot activity, likely induced by rapid stellar rotation.

79 ASTRONOMY AND ASTROPHYSICS↗

A signal compensation based cascaded PI control for an industrial heat exchange system

Since the characteristics of the industrial heat exchange system (HES) are drastically affected by variations of the steam pressure, ambient temperature and water quality, it is difficult for the classical cascade PI control system to meet the desirable control objectives. Therefore, in this paper, a deterministic linear model with unmodeled dynamics is used to describe the dynamic characteristics of the HES. It should be noted that the unmodeled dynamics at the previously sampled instant can be calculated using actual measurements and that the tracking error, which includes effects of the rate of changes of unmodeled dynamics on the controlled model, can be accurately determined. An additional compensating signal is obtained with the feedforward control together with a one-step optimal control law. Consequently, the cascade PI control strategy with the signal compensation is established. Furthermore, the simulation and industrial application show that the proposed method can effectively improve the performance of the cascade PI control system, especially when the unmodeled dynamics is subjected to unknown variations.

42 ENGINEERING↗

Demonstrating Advanced Sensors for In-Situ Monitoring Towards Qualification of Nuclear Relevant Components

The U.S. Department of Energy’s Office of Nuclear Energy Advanced Materials and Manufacturing Technologies (AMMT) program is pursuing qualification of laser powder bed fusion (LPBF) components for nuclear applications. A major focus of this effort is the use of in situ process monitoring and machine learning–based tools to establish real-time quality assurance. The primary objective of this report is to identify and evaluate the most relevant in situ sensor systems for LPBF, and to document the deployment of these systems across platforms critical to the AMMT program. This work demonstrates how in situ monitoring can detect process anomalies, track geometry-dependent flaws, and identify limiting combinations of processing parameters—particularly those related to energy density and complex geometries (e.g., overhanging structures). To support this goal, a diverse suite of sensor modalities was evaluated across LPBF platforms, including visible and near-infrared (NIR) imaging, fringe projection profilometry, long-wavelength infrared (LWIR) thermography, and high-speed photodiode/pyrometry systems. These sensor streams were integrated with Peregrine, a machine-agnostic software platform that, among other capabilities, can generate real-time process anomaly classification. This report documents sensor deployments on multiple AMMT flagship platforms, including the Concept Laser M2 and Renishaw AM400/AM250 systems. Calibration builds with complex, flaw-prone geometries such as unsupported overhangs, stepped features, and thin walls, were used to evaluate how well Peregrine and its associated sensors could detect process anomalies and other instabilities under varied energy densities. It will be shown how Peregrine reliably identifies common process anomalies such as recoater streaking, superelevation, etc., and can be used in post-build analysis for anomaly spatial distributions throughout the build height to better understand the impact of geometry and processing parameter choice on the build. This work demonstrates measurable progress toward the vision that components can be born-qualified by establishing a real-time monitoring framework, identifying limiting process conditions, and laying the foundation for sensor fusion–enabled prediction pipelines that are scalable across platforms and applicable to nuclear-relevant components.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

An orientable, stabilized balloon-borne gondola for around-the-world flights

A system capable of pointing a balloon-borne telescope at selected celestial objects to an accuracy of approximately 10 arc minutes for an extended period (weeks to months) without reliance on telemetry is described. A unique combination of a sun/star tracker, an on-board computer, and a gyrocompass is utilized for navigation, source acquisition and tracking, and data compression and recording. The possibilities for intelligent activities by the computer are also discussed.

Ricker, G. R.↗

International time transfer and portable clock evaluation using GPS timing receivers: Preliminary results

The overall experiment was designed to test the positioning and navigation capabilities of the GPS timing receivers developed by the Naval Research Laboratory (NRL) for the NASA Goddard Laser Tracking Network (GITN). To perform this experiment, a reliable and redundant time scale was set up onboard the ship, and a back-up on shore. This situation provided the opportunity to perform simultaneously a timing experiment ideally divided into two parts, the main objectives of the experimentation being: (1) To test GPS timing receiver synchronization capabilities on a moving platform, and to perform an intercontinental synchronization via GPS between participating international timing laboratories in Europe and in the United States. (2) To evaluate the performance of cesium portable clocks in the field.

Wardrip, S. C.↗

Robust integrated autopilot/autothrottle design using constrained parameter optimization

A multivariable control design method based on constrained parameter optimization was applied to the design of a multiloop aircraft flight control system. Specifically, the design method is applied to the following: (1) direct synthesis of a multivariable 'inner-loop' feedback control system based on total energy control principles; (2) synthesis of speed/altitude-hold designs as 'outer-loop' feedback/feedforward control systems around the above inner loop; and (3) direct synthesis of a combined 'inner-loop' and 'outer-loop' multivariable control system. The design procedure offers a direct and structured approach for the determination of a set of controller gains that meet design specifications in closed-loop stability, command tracking performance, disturbance rejection, and limits on control activities. The presented approach may be applied to a broader class of multiloop flight control systems. Direct tradeoffs between many real design goals are rendered systematic by this method following careful problem formulation of the design objectives and constraints. Performance characteristics of the optimization design were improved over the current autopilot design on the B737-100 Transport Research Vehicle (TSRV) at the landing approach and cruise flight conditions; particularly in the areas of closed-loop damping, command responses, and control activity in the presence of turbulence.

Ly, Uy-Loi↗

Geoid-to-topography ratios on Venus: A global perspective

Recently available spherical harmonic solutions for the geoid and topography of Venus are sufficiently high resolution that they can be used to address questions concerning the relationship between geoid and topography on a regional scale. We have approached this question by mapping the geoid-to-topography ratio (GTR) on a systematic global basis. For a given point on the surface, we consider the geoid and elevation values at all points on a gridded representation of those fields located within a specified distance of the reference point. From the set of paired values, we determine the correlation coefficient and the best-fitting straight line. The latter is the GTR at that position, and the former is a measure of the significance of the derived ratio. This procedure is then repeated for all points on the global grid, yielding maps of the GTR and the correlation coefficient. Unlike previous studies of the GRT on Venus, this apprach permits us to make an objective and systematic search for regions with anomalous GTR's as well as areas that do not demonstrate any strong correlation between geoid and topography. These maps can be updated regularly as new harmonic models of the Venus geoid are produced from new Magellan tracking data. This procedure permits the development of a global perspective on the relationship between GTR and venusian surface tectonics.

Simons, Mark↗

STS-68 Space Shuttle mission report

The STS-68 Space Shuttle Program Mission Report summarizes the Payload activities as well as the Orbiter, External Tank (ET), Solid Rocket Booster (SRB), Redesigned Solid Rocket Motor (RSRM), and the Space Shuttle main engine (SSME) systems performance during the sixty-fifth flight of the Space Shuttle Program and the seventh flight of the Orbiter vehicle Endeavour (OV-105). In addition to the Orbiter, the flight vehicle consisted of an ET that was designated ET-65; three SSMEs that were designated as serial numbers 2028, 2033, and 2026 in positions 1, 2, and 3, respectively; and two SRBs that were designated BI-067. The RSRMs that were installed in each SRB were designated as 360W040A for the left SRB and 360W040B for the right SRB. The primary objective of this flight was to successfully perform the operations of the Space Radar Laboratory-2 (SRL-2). The secondary objectives of the flight were to perform the operations of the Chromosome and Plant Cell Division in Space (CHROMEX), the Commercial Protein Crystal Growth (CPCG), the Biological Research in Canisters (BRIC), the Cosmic Radiation Effects and Activation Monitor (CREAM), the Military Application of Ship Tracks (MAST), and five Get-Away Special (GAS) payloads.

Fricke, Robert W., Jr.↗

Methods to Improve the Maintenance of the Earth Catalog of Satellites During Severe Solar Storms

The objective of this thesis is to investigate methods to improve the ability to maintain the inventory of orbital elements of Earth satellites during periods of atmospheric disturbance brought on by severe solar activity. Existing techniques do not account for such atmospheric dynamics, resulting in tracking errors of several seconds in predicted crossing time. Two techniques are examined to reduce of these tracking errors. First, density predicted from various atmospheric models is fit to the orbital decay rate for a number of satellites. An orbital decay model is then developed that could be used to reduce tracking errors by accounting for atmospheric changes. The second approach utilizes a Kalman filter to estimate the orbital decay rate of a satellite after every observation. The new information is used to predict the next observation. Results from the first approach demonstrated the feasibility of building an orbital decay model based on predicted atmospheric density. Correlation of atmospheric density to orbital decay was as high as 0.88. However, it is clear that contemporary: atmospheric models need further improvement in modeling density perturbations polar region brought on by solar activity. The second approach resulted in a dramatic reduction in tracking errors for certain satellites during severe solar Storms. For example, in the limited cases studied, the reduction in tracking errors ranged from 79 to 25 percent.

Wilkin, Paul G.↗

SOFTC: A Software Correlator for VLBI

SOFTC is an advanced software implementation of a signal correlator for very-long-baseline interferometry (VLBI) for measuring positions of natural celestial objects and distant spacecraft. Because of increases in processing speeds of general-purpose computers, software VLBI correlators have become viable alternatives to hardware ones. The input to SOFTC consists of digitized samples of raw VLBI-antenna received- signal voltages. Optionally, SOFTC also tracks calibration tones superimposed on the received signals. The outputs of SOFTC are (1) phases and amplitudes as functions of time and frequency for cross-correlated received signals and (2) phases and amplitudes as functions of time, station, and tone number for the calibration tones. SOFTC was created to be as accurate as possible, capable of processing essentially any VLBI data, pass strong debugging tests, have a simple user interface, and have no platform dependencies. SOFTC is written modularly in the C programming language. The great advantage of implementing a correlator in software, in contradistinction to hardware, is that it becomes relatively easy and much less expensive and time-consuming to adapt, modify, improve, and update the correlator.

Lowe, Stephen↗

The Determination of the Rotational State and Interior Structure of Venus with VERITAS

Understanding the processes that led Venus to its current state and will drive its future evolution is a major objective of the next generation of orbiters. In this work we analyze the retrieval of the spin vector, the tidal response and the moment of inertia of Venus with VERITAS, a NASA Discovery-class mission. By simulating a systematic joint analysis of Doppler tracking data and tie points provided by the onboard synthetic aperture radar we show that VERITAS will provide accuracies (3σ) in the estimates of the tidal Love number k_2 to 4.6×10^(-4), its tidal phase lag to 0.05°, and the moment of inertia factor to 9.8×10^(-4) (0.3% of the expected value). Applying these results to recent models of the Venus interior, we show that VERITAS will provide much improved constraints on the interior structure of the planet.

G Cascioli↗

Transient cycling of nitrogen, organic carbon and oxygen within the free-flowing Columbia River corridor: Linking exposure time dependent biogeochemical reactions to river stage fluctuations (Final project report)

The objective of this project was to develop next-generation techniques for representing the transformations of complex reaction networks like those impacting transient river-corridors, then apply them to develop upscaling tools. The project contributed significantly to the development of Lagrangian “mass transfer particle tracking” (MTPT) tools that are the first numerical framework that explicitly separates mixing and spreading processes; a crucial distinction for accurate representations of reaction rates across scales. The MTPT approach uses an operator splitting scheme where physical transport processes are simulated using classical random walk methods and each particle is treated as a “container” that carries with it any number of chemical species. Mixing between particles is simulated using a colocation-probability based mass transfer kernel and reactions are evaluated on each particle after mixing. The method is stable, accurate, and also allows the explicit modeling of residence time distributions of the individual containers of mass. The MTPT scheme allowed us to explore several research questions related to reactive transport in river corridors and complex reaction networks. We found that it is possible to quantify the exposure time distributions (ETDs) of reactants and that this does suggest some pathways to upscaling. However, comparable approximations can be obtained using simplified (reduced dimensionality) MTPT simulations in less time with similar uncertainty, so development of extensive ETD-based methods was not productive. The major findings are that i) the MTPT schemes are robust and highly accurate across a range of arbitrarily complex reactions, ii) the methods can be efficiently parallelized and the parallel performance characteristics of MTPT are predictable, and iii) the MTPT tools allow simultaneous tracking of residence time. The development of these research tools into efficient software packages continues. The methods are already available to the community because open-source, working examples have been included with all publications.

54 ENVIRONMENTAL SCIENCES↗

Low-Altitude AVIRIS Data for Mapping Land Cover in Yellowstone National Park: Use of Isodata Clustering Techniques

Northeast Yellowstone National Park (YNP) has a diversity of forest, range, and wetland cover types. Several remote sensing studies have recently been done in this area, including the NASA Earth Observations Commercial Applications Program (EOCAP) hyperspectral project conducted by Yellowstone Ecosystems Studies (YES) on the use of hyperspectral imaging for assessing riparian and in-stream habitats. In 1999, YES and NASA's Commercial Remote Sensing Program Office began collaborative study of this area, assessing the potential of synergistic use of hyperspectral, synthetic aperture radar (SAR), and multiband thermal data for mapping forest, range, and wetland land cover. Since the beginning, a quality 'reference' land cover map has been desired as a tool for developing and validating other land cover maps produced during the project. This paper recounts an effort to produce such a reference land cover map using low-altitude Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data and unsupervised classification techniques. The main objective of this study is to assess ISODATA classification for mapping land cover in Northeast YNP using select bands of low-altitude AVIRIS data. A secondary, more long-term objective is to assess the potential for improving ISODATA-based classification of land cover through use of principal components analysis and minimum noise fraction (MNF) techniques. This paper will primarily report on work regarding the primary research objective. This study focuses on an AVIRIS cube acquired on July 23, 1999, by the confluence of Soda Butte Creek with the Lamar River. Range and wetland habitats dominate the image with forested habitats being a comparatively minor component of the scene. The scene generally tracks from southwest to northeast. Most of the scene is valley bottom with some lower side slopes occurring on the western portion. Elevations within the AVIRIS scene range from approximately 1998 to 2165 m above sea level, based on US Geological Survey (USGS) 30-m digital elevation model (DEM) data. Despain and the National Park Service (NPS) provide additional description of the study area.

Spruce, Joseph P.↗