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At least 1,405 records · Page 78

Evaporation in the transition region during the gradual phase of flares

Previous observations have revealed that small, but sustained, H-alpha blueshifts occur in flare ribbons during the gradual, or late, phase of flares. These blueshifts suggest that there is a gentle evaporation of chromospheric material throughout the late phase of flares, but ambiguities in the interpretation of H-alpha leave open the possibility that these blueshifts are caused by downflowing, rather than upflowing, material. Using both C IV and soft (3.5-8 keV) X-ray data from SMM observations, evidence is found which supports the interpretation of the H-alpha blueshifts as upflows in the range from 4-12 km/s. The blueshifts are interpreted in terms of the reconnection model proposed by Carmichael (1964). The model produces a sustained energy release through-out the late phase which accounts for the prolonged soft X-ray emission after a flare. This energy release comes from the reconnecting magnetic field above the flare site, and some of the energy is transported along field lines mapping to the chromosphere where it drives chromospheric evaporation.

Schmieder, B.↗

Airborne gravimetry, altimetry, and GPS navigation errors

Proper interpretation of airborne gravimetry and altimetry requires good knowledge of aircraft trajectory. Recent advances in precise navigation with differential GPS have made it possible to measure gravity from the air with accuracies of a few milligals, and to obtain altimeter profiles of terrain or sea surface correct to one decimeter. These developments are opening otherwise inaccessible regions to detailed geophysical mapping. Navigation with GPS presents some problems that grow worse with increasing distance from a fixed receiver: the effect of errors in tropospheric refraction correction, GPS ephemerides, and the coordinates of the fixed receivers. Ionospheric refraction and orbit error complicate ambiguity resolution. Optimal navigation should treat all error sources as unknowns, together with the instantaneous vehicle position. To do so, fast and reliable numerical techniques are needed: efficient and stable Kalman filter-smoother algorithms, together with data compression and, sometimes, the use of simplified dynamics.

Colombo, Oscar L.↗

Recent Progress in Entry Radiation Measurements in the NASA Ames Electric ARC Shock Tube Facility

The Electric Arc Shock Tube (EAST) at NASA Ames Research Center is NASA's only working shock tube capable of obtaining conditions representative of entry in a multitude of planetary atmospheres. The facility is capable of mapping spectroscopic signatures of a wide range of planetary entries from the Vacuum Ultraviolet through Mid-Wave Infrared (120-5500 nm). This paper summarizes the tests performed in EAST for Earth, Mars and Venus entries since 2008, then focuses on a specific test case for CO2/N2 mixtures. In particular, the paper will focus on providing information for the proper interpretation of the EAST data.

Cruden, Brett A.↗

Mimas: Preliminary Evidence For Amorphous Water Ice from VIMS

We have conducted a statistical clustering analysis (1,2) on a mosaic of VIMS data cubes obtained on February 13, 2010, for Saturn s satellite Mimas. Seven VIMS cubes were geometrically projected and re-sampled to a common spatial resolution. The clustering technique consists of a partitioning algorithm coupled to a criterion that prevents sub-optimal solutions and tests for the influence of random noise in the measurements. The clustering technique is agnostic about the meaning of the clusters, and scientific interpretation requires their a posteriori evaluation. The preliminary results yielded five clusters, demonstrating that spectral variability across Mimas surface is statistically significant. The ratios of the means calculated for each of the clusters show structure within the 1.6- micron water ice band, as well as the shape and the central wavelength of the strong ice band at 2 micron, that map spatially in patterns apparently related to the topography of Mimas, in particular certain regions in and around Herschel crater. The mean spectra of the five clusters, show similarities with laboratory spectra of amorphous and crystalline H2O ice (3) that are suggestive of the presence of an amorphous ice component in certain regions of Mimas, notably on the central peak of Herschel, on the crater floor, and in faults surrounding the crater. This may represent a mixture of both ice phases, or perhaps a layer of amorphous ice on a base of crystalline ice. Another possible occurrence of amorphous ice appears southwest of Herschel, close to the south pole.

Cruikshank, Dale P.↗

Mapping Benthic Habitat Conditions and Seafloor Deposits using Sediment Profile Imaging and a Semiautomated Image Processing System

Objectives/Scope: Sediment profile imaging (SPI) technology characterizes in situ physical, geochemical, and biological seafloor features. SPI was required by Mexico’s Agency for Safety, Energy, and Environment in 2017 for environmental baseline surveys (EBS) of oil lease blocks in the southern Gulf of Mexico. Because of its ability to provide information on benthic community health and the distribution of very thin (down to the centimeter scale) layers of deposited materials, SPI technology is highly effective for mapping drill cuttings or drilling muds released around wellheads during exploration or production and documenting their ecological impacts. SPI technology has not been widely used in the oil and gas industry for EBS or other monitoring activities. A primary objective of this work is to improve the transparency and consistency of the SPI data generation and data management process. Methods, Procedures, Process: The SPI camera works like an inverted periscope and obtains an undisturbed 21x15-cm cross-sectional image of the upper sediment column. The camera is internally powered and can be deployed rapidly from a standard winch in depths to 4,000 m. Many stations can be sampled in a single day by “pogo-sticking” across a survey area. Sediment grain size, penetration depth, surface boundary roughness, natural and anthropogenic depositional layers, depth of the oxidized surface sediment layer, maximum biogenic mixing depth, and infaunal successional stage can be directly measured at sea or immediately following the cruise. Final SPI data sets can be provided within a few weeks of the survey. Results, Observations, Conclusions: Details on the features measured in SPI images and the underlying interpretive paradigms are presented. To standardize the SPI data generation process, Integral Consulting Inc. has developed 1) a semiautomated image analysis platform, and 2) a SPI data-specific database architecture that allows both numerical and non-numerical metrics to be incorporated into a standard database structure. An integrated, software-based SPI analysis platform has been developed that imports image files and metadata and provides a graphical user interface. The software automatically stores the data, which can then be reviewed for quality assurance, plotted, statistically analyzed, and mapped or exported to other platforms (e.g., Esri ArcGIS©) for further evaluation. Image processing algorithms have been developed using a combination of open-source and commercially available software packages (e.g., MATLAB® and OpenCV) to automatically quantify key parameters. Novel/Additive Information: SPI technology’s underutilization in the oil and gas industry may be in part due to a lack of standardization in the measurement of basic features in SPI images. A primary objective of this work is to develop a streamlined, standardized, and transparent process for generating and managing SPI data.

02 PETROLEUM↗

Analysis and interpretation of diffuse x-ray emission using data from the Einstein satellite

An ambitious program to create a powerful and accessible archive of the HEAO-2 Imaging Proportional Counter (IPC) database was outlined. The scientific utility of that database for studies of diffuse x ray emissions was explored. Technical and scientific accomplishments are reviewed. Three papers were presented which have major new scientific findings relevant to the global structure of the interstellar medium and the origin of the cosmic x ray background. An all-sky map of diffuse x ray emission was constructed.

Helfand, David J.↗

Tomographic galaxy clustering with the Subaru Hyper Suprime-Cam first year public data release

We analyze the clustering of galaxies in the first public data release of the HSC Subaru Strategic Program. Despite the relatively small footprints of the observed fields, the data are an excellent proxy for the deep photometric datasets that will be acquired by LSST, and are therefore an ideal test bed for the analysis methods being implemented by the LSST DESC. We select a magnitude limited sample with i<24.5 and analyze it in four redshift bins covering 0.15≲z≲1.5. We carry out a Fourier-space analysis of the two-point clustering of this sample, including all auto- and cross-correlations. We demonstrate the use of map-level deprojection methods to account for fluctuations in the galaxy number density caused by observational systematics. Through an HOD analysis, we place constraints on the characteristic halo masses of this sample, finding a good fit up to scales k max = 1Mpc –1 , including both auto- and cross-correlations. Our results show monotonically decreasing average halo masses, which can be interpreted in terms of the drop-out of red galaxies at high redshifts for a flux-limited sample. In terms of photometric redshift systematics, we show that additional care is needed in order to marginalize over uncertainties in the redshift distribution in galaxy clustering, and that these uncertainties can be constrained by including cross-correlations. We are able to make a ~3σ detection of lensing magnification in the HSC data. Our results are stable to variations in σ 8 and Ω c and we find constraints that agree well with measurements from Planck and low-redshift probes. Lastly, we use our pipeline to study the clustering of galaxies as a function of limiting flux, and provide a simple fitting function for the linear galaxy bias for magnitude limited samples as a function of limiting magnitude and redshift.

79 ASTRONOMY AND ASTROPHYSICS↗

Microscopic scattering approach to in-gap states: Cr adatoms on superconducting 𝛽−Bi 2 ⁢Pd

We develop a microscopic scattering formalism to describe Yu-Shiba-Rusinov (YSR) states due to a single Cr adatom on the Bi-terminated surface of 𝛽−Bi 2 ⁢Pd, by combining ab initio Wannier functions with a real-space Green's function approach in the Bogoliubov–de Gennes formalism. Our framework reproduces key scanning tunneling spectroscopy features, including a single particle-hole asymmetric YSR peak and isotropic 𝑑⁢𝐼/𝑑⁢𝑉 maps around the impurity. Decomposing the YSR states reveals contributions from four nearly degenerate 𝐶 4⁢𝑣 representations, with energy broadening masking their individual signatures. Spin-orbit coupling induces partial spin polarization, while the spatial asymmetry between particle and hole components arises from Cr 𝑑−Bi 𝑝 hybridization. These results highlight the importance of realistic band structures and microscopic modeling for interpreting STM data and provide a foundation for studying impurity chains hosting topological excitations.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

Microscopic Scattering Approach to In-Gap States

We develop a microscopic scattering formalism to describe Yu-Shiba-Rusinov (YSR) states due to a single Cr adatom on the Bi-terminated surface of beta Bi2Pd, by combining ab initio Wannier functions with a real-space Green's function approach in the Bogoliubov-de Gennes formalism[1]. Our framework reproduces key scanning tunneling spectroscopy features, including a single particle-hole asymmetric YSR peak and isotropic dIdV maps around the impurity. Decomposing the YSR states reveals contributions from four nearly degenerate C4v representations, with energy broadening masking their individual signatures. Spin-orbit coupling induces partial spin polarization, while the spatial asymmetry between particle and hole components arises from Cr d-Bi p hybridization. These results highlight the importance of realistic band structures and microscopic modeling for interpreting STM data for magnetic in-gap states on superconductors. Further advances examining layered 2D material surfaces, such as NbSe2, will be described[2]. For this system the superconducting properties are obtained from a full anisotropic Eliashberg calculation of the superconducting order parameter along with the charge density wave gap. Additional features associated with proposals to measure the dynamics of these individual YSR states will be presented. [1] arXiv:2507.08740 [2] arXiv:2507.11856

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

Investigation of the utility of ERTS-1 imagery for updating land use and resource data in Guatemala

The author has identified the following significant results. An intensive analysis of the imagery received has been completed and findings are reported. Conclusions are restricted by receipt of only limited amounts of cloud-free coverage of test areas. In most cases the interpretation findings were as anticipated from previous experience with multiband images. Band 7 provides promising indication of some economically important environmental communities. It also permits viewing through thin cirrus cloud layers for features of medium to high contrast. Band 4 provides information of submerged reefs and of movement of suspended sediment bodies in water areas. ERTS-1 bulk images have positional mapping accuracy adequate for representation at 1:1,000,000 scale maps. Cloud cover is a true constraint to useable satellite coverage.

Garcia, L. E.↗

Correlation signatures of wet soils and snows

Interpretation, analysis, and development of algorithms have provided the necessary computational programming tools for soil data processing, data handling and analysis. Algorithms that have been developed thus far, are adequate and have been proven successful for several preliminary and fundamental applications such as software interfacing capabilities, probability distributions, grey level print plotting, contour plotting, isometric data displays, joint probability distributions, boundary mapping, channel registration and ground scene classification. A description of an Earth Resources Flight Data Processor, (ERFDP), which handles and processes earth resources data under a users control is provided.

Phillips, M. R.↗

Using spatial logic in classification of Landsat TM data

A strategy for spatial/spectral classification of Landsat TM data is presented. The strategy is founded upon 'spatial logic', a logic that seeks to emulate important aspects of visual image interpretation. The carefully structured classification process begins with spectral stratification of the data into water, vegetated and non-vegetated pixels. A region growing algorithm is then used to define 'fields' of similar land cover composition. Fields are characterized by cover composition, size and neighborhood characteristics. A supervised iterative contextual classification algorithm is developed to assign final land use/land cover labels. Maps are generalized using a spatial post-processing technique. Positive, though preliminary, results are presented.

Merchant, J. W.↗

A method for selecting an operations concept to achieve successful mission operations

A procedure is presented for mapping operations concepts into design alternatives for a data system to be used in a generic ground based control center. A set of descriptive categories are developed to characterize the operational environment that relate to responsiveness, automation, and commitment. The operations concept is then developed according to a hierarchical decomposition of a mission statement into lower-level tasks, and the interpretation of the model's output is addressed. The method permits the description of operations concepts in terms of concept categories and ranges of alternatives between those categories. The descriptive framework can provide a mechanism for analyzing competing operations concepts.

Hornstein, Rhoda S.↗

Incorporating Manual and Autonomous Code Generation

Code can be generated manually or using code-generated software tools, but how do you interpret the two? This article looks at a design methodology that combines object-oriented design with autonomic code generation for attitude control flight software. Recent improvements in space flight computers are allowing software engineers to spend more time engineering the applications software. The application developed was the attitude control flight software for an astronomical satellite called the Microwave Anisotropy Probe (MAP). The MAP flight system is being designed, developed, and integrated at NASA's Goddard Space Flight Center. The MAP controls engineers are using Integrated Systems Inc.'s MATRIXx for their controls analysis. In addition to providing a graphical analysis for an environment, MATRIXx includes an autonomic code generation facility called AutoCode. This article examines the forces that shaped the final design and describes three highlights of the design process: (1) Defining the manual to autonomic code interface; (2) Applying object-oriented design to the manual flight code; (3) Implementing the object-oriented design in C.

McComas, David↗

Geologic Map of the Snegurochka Planitia Quadrangle (V-1): Implications for the Volcanic History of the North Polar Region of Venus

Geologic mapping of Snegurochka Planitia (V-1) reveals a complex stratigraphy of tectonic and volcanic features that can provide insight into the geologic history of Venus and Archean Earth [1,2], including 1) episodes of both localized crustal uplift and mantle downwelling, 2) shifts from local to regional volcanic activity, and 3) a shift back to local volcanic activity. We present our interpretations of the volcanic history of the region surrounding the north pole of Venus and explore how analysis of new data support our interpretations

Hurwitz, D. M.↗

Observational evidence and dynamical interpretation of the total ozone variations in the equatorial region

The total ozone amount is sensitive to the general circulation changes in the lower stratosphere due to the photochemically inactive nature of ozone there. In the equatorial region, such circulation changes arise from the quasi-biennial oscillation (QBO) of the stratospheric zonal wind and the El Nino/Southern Oscillation (ENSO). In the first half of this study we present observational results of the long-term variations in the equatorial ozone field using the 11 year Total Ozone Mapping Spectrometer (TOMS) data, by paying special attention to the longitudinal structure. In the latter half we try to understand quantitatively these variations by using a simple mechanistic relationship. We hypothesis that the ozone modulating processes are attributable to two dynamical effects, the advection effect and tropopause effect, owing to the strong vertical stratification of ozone existing just above the tropopause. The advection effect comes from the vertical motion which maintains the temperature structure, compensating for the radiative damping. The tropopause effect is associated with the altitude change of the tropopause. The total ozone variations in the tropics is discussed in terms of these two dynamical processes with the aid of mechanistic equations combined with the wind and sea surface temperature (SST) observations. The interactions between tropical and extratropical latitudes are beyond the scope of this study. Photochemical effects are also neglected. Details of this study are given by Shiotani (1992) and Hasebe (1992).

Shiotani, Masato↗

Constraints on iron sulfate and iron oxide mineralogy from ChemCam visible/near-infrared reflectance spectroscopy of Mt. Sharp basal units, Gale Crater, Mars

Relative reflectace point spectra (400–840 nm) were acquired by the Chemistry and Camera (ChemCam) instrument on the Mars Science Laboratory (MSL) rover Curiosity in passive mode (no laser) of drill tailings and broken rock fragments near the rover as it entered the lower reaches of Mt. Sharp and of landforms at distances of 2–8 km. Freshly disturbed surfaces are less subject to the spectral masking effects of dust, and revealed spectral features consistent with the presence of iron oxides and ferric sulfates. Here, we present the first detection on Mars of a ~433 nm absorption band consistent with small abundances of ferric sulfates, corroborated by jarosite detections by the Chemistry and Mineralogy (CheMin) X-ray diffraction instrument in the Mojave, Telegraph Peak, and Confidence Hills drilled samples. The disturbed materials near the Bonanza King region also exhibited strong 433 nm bands and negative near-infrared spectral slopes consistent with jarosite. ChemCam passive spectra of the Confidence Hills and Mojave drill tailings showed features suggestive of the crystalline hematite identified by CheMin analyses. The Windjana drill sample tailings exhibited flat, low relative reflectance spectra, explained by the occurrence of magnetite detected by CheMin. Passive spectra of Bonanza King were similar, suggesting the presence of spectrally dark and neutral minerals such as magnetite. Long-distance spectra of the “Hematite Ridge” feature (3–5 km from the rover) exhibited features consistent with crystalline hematite. The Bagnold dune field north of the Hematite Ridge area exhibited low relative reflectance and near-infrared features indicative of basaltic materials (olivine, pyroxene). Light-toned layers south of Hematite Ridge lacked distinct spectral features in the 400–840 nm region, and may represent portions of nearby clay minerals and sulfates mapped with orbital near-infrared observations. The presence of ferric sulfates such as jarosite in the drill tailings suggests a relatively acidic environment, likely associated with flow of iron-bearing fluids, associated oxidation, and/or hydrothermal leaching of sedimentary rocks. Combined with other remote sensing data sets, mineralogical constraints from ChemCam passive spectra will continue to play an important role in interpreting the mineralogy and composition of materials encountered as Curiosity traverses further south within the basal layers of the Mt. Sharp complex.

58 GEOSCIENCES↗

Soft X-ray emission from the Lupus Loop and Sn 1006 supernova remnants

X-ray maps of the Lupus region have been obtained in a raster scan observation from SAS 3. These show the Lupus Loop to be a faint extended source of soft X-rays with a temperature about 2.5 million K. The most prominent feature of the region is the A.D. 1006 supernova remnant, which is unexpectedly bright at 0.2-1.0 keV. One speculative interpretation of the low-energy flux from SN 1006 is as blackbody radiation from a hot neutron star.

Winkler, P. F., Jr.↗