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NASA NTRS2016

The Variable Crab Nebula: Evidence for a Connection Between GeV Flares and Hard X-ray Variations

In 2010, hard X-ray variations (Wilson-Hodge et al. 2011) and GeV flares (Tavani et al 2011, Abdo et al. 2011) from the Crab Nebula were discovered. Connections between these two phenomena were unclear, in part because the timescales were quite different, with yearly variations in hard X-rays and hourly to daily variations in the GeV flares. The hard X-ray flux from the Crab Nebula has again declined since 2014, much like it did in 2008-2010. During both hard X-ray decline periods, the Fermi LAT detected no GeV flares, suggesting that injection of particles from the GeV flares produces the much slower and weaker hard X-ray variations. The timescale for the particles emitting the GeV flares to lose enough energy to emit synchrotron photons in hard X-rays is consistent with the yearly variations observed in hard X-rays and with the expectation that the timescale for variations slowly increases with decreasing energy. This hypothesis also predicts even slower and weaker variations below 10 keV, consistent with the non-detection of counterparts to the GeV flares by Chandra (Weisskopf et al 2013). We will present a comparison of the observed hard X-ray variations and a simple model of the decay of particles from the GeV flares to test our hypothesis.

Variable Crab Nebula↗
NASA NTRS2016

Application of the Molecular Adsorber Coating Technology on the Ionospheric Connection Explorer Program

The Molecular Adsorber Coating (MAC) is a zeolite based highly porous coating technology that was developed by NASA Goddard Space Flight Center (GSFC) to capture outgassed contaminants, such as plastics, adhesives, lubricants, silicones, epoxies, potting compounds, and other similar materials. This paper describes the use of the MAC technology to address molecular contamination concerns on NASAs Ionospheric Connection Explorer (ICON) program led by the University of California (UC) Berkeleys Space Sciences Laboratory. The sprayable paint technology was applied onto plates that were installed within the instrument cavity of ICONs Far Ultraviolet Imaging Spectrograph (FUV). However, due to the instruments particulate sensitivity, the coating surface was vibrationally cleaned through simulated acoustics to reduce the risk of particle fall-out contamination. This paper summarizes the coating application efforts on the FUV adsorber plates, the simulated laboratory acoustic level cleaning test methods, particulation characteristics, and future plans for the MAC technology.

outgassing↗
NASA NTRS2016

Ensemble Mean Density and its Connection to Other Microphysical Properties of Falling Snow as Observed in Southern Finland

In this study measurements collected during winters 2013/2014 and 2014/2015 at the University of Helsinki measurement station in Hyytiala are used to investigate connections between ensemble mean snow density, particle fall velocity and parameters of the particle size distribution (PSD). The density of snow is derived from measurements of particle fall velocity and PSD, provided by a particle video imager, and weighing gauge measurements of precipitation rate. Validity of the retrieved density values is checked against snow depth measurements. A relation retrieved for the ensemble mean snow density and median volume diameter is in general agreement with previous studies, but it is observed to vary significantly from one winter to the other. From these observations, characteristic mass- dimensional relations of snow are retrieved. For snow rates more than 0.2mm/h, a correlation between the intercept parameter of normalized gamma PSD and median volume diameter was observed.

Tiira, Jussi↗
NASA NTRS2016

Disk-Wind Connection During the Heartbeats of GRS 1915+105

Disk and wind signatures are seen in the soft state of Galactic black holes, while the jet is seen in the hard state. Here we study the disk-wind connection in the Rho class of variability in GRS 1915+105 using a joint NuSTAR-Chandra observation. The source shows 50 s limit cycle oscillations. By including new information provided by the reflection spectrum and using phase-resolved spectroscopy, we find that the change in the inner disk inferred from the blackbody emission is not matched by reflection measurements. The latter is almost constant, independent of the continuum model. The two radii are comparable only if the disk temperature color correction factor changes, an effect that could be due to the changing opacity of the disk caused by changes in metal abundances. The disk inclination is similar to that inferred from the jet axis, and oscillates by approx.10 deg. The simultaneous Chandra data show the presence of two wind components with velocities between 500 and 5000 km s(exp. −1), and possibly two more with velocities reaching 20,000 km s(exp. −1) (approx. 0.06 c). The column densities are approx. 5 × 10(exp. 22) cm(exp. −2). An upper limit to the wind response time of 2 s is measured, implying a launch radius of less than 6 × 10(exp. 10) cm. The changes in wind velocity and absorbed flux require the geometry of the wind to change during the oscillations, constraining the wind to be launched from a distance of 290-1300 r (sub g) from the black hole. Both data sets support fundamental model predictions in which a bulge originates in the inner disk and moves outward as the instability progresses.

accretion↗
NASA NTRS2017

Exploring Connectivity in Sequence Space of Functional RNA

Emergence of replicable genetic molecules was one of the marking points in the origin of life, evolution of which can be conceptualized as a walk through the space of all possible sequences. A theoretical concept of fitness landscape helps to understand evolutionary processes through assigning a value of fitness to each genotype. Then, evolution of a phenotype is viewed as a series of consecutive, single-point mutations. Natural selection biases evolution toward peaks of high fitness and away from valleys of low fitness. whereas neutral drift occurs in the sequence space without direction as mutations are introduced at random. Large networks of neutral or near-neutral mutations on a fitness landscape, especially for sufficiently long genomes, are possible or even inevitable. Their detection in experiments, however, has been elusive. Although a few near-neutral evolutionary pathways have been found, recent experimental evidence indicates landscapes consist of largely isolated islands. The generality of these results, however, is not clear, as the genome length or the fraction of functional molecules in the genotypic space might have been insufficient for the emergence of large, neutral networks. Thorough investigation on the structure of the fitness landscape is essential to understand the mechanisms of evolution of early genomes. RNA molecules are commonly assumed to play the pivotal role in the origin of genetic systems. They are widely believed to be early, if not the earliest, genetic and catalytic molecules, with abundant biochemical activities as aptamers and ribozymes, i.e. RNA molecules capable, respectively, to bind small molecules or catalyze chemical reactions. Here, we present results of our recent studies on the structure of the sequence space of RNA ligase ribozymes selected through in vitro evolution. Several hundred thousands of sequences active to a different degree were obtained by way of deep sequencing. Analysis of these sequences revealed several large clusters defined such that every sequence in a cluster can be reached from any other sequence in the same cluster through a series of single point mutations. Sequences in a single cluster appear to adopt more than one secondary structure. The mechanism of refolding within a single cluster was examined. To shed light on possible evolutionary paths in the space of ribozymes, the connectivity between clusters was investigated. The effect of length of RNA molecules on the structure of the fitness landscape and possible evolutionary paths was examined by way of comparing functional sequences of 20 and 80 nucleobases in length. It was found that sequences of different lengths shared secondary structure motifs that were presumed responsible for catalytic activity, with increasing complexity and global structural rearrangements emerging in longer molecules.

Wei, Chenyu↗
NASA NTRS2018

Process for Fabrication of Superconducting Vias for Electrical Connection to Groundplane in Cryogenic Detectors

Disclosed are systems, methods, and non-transitory computer-readable storage media for fabrication of silicon on insulator (SOI) wafers with a superconductive via for electrical connection to a groundplane. Fabrication of the SOI wafer with a superconductive via can involve depositing a superconducting groundplane onto a substrate with the superconducting groundplane having an oxidizing layer and a non-oxidizing layer. A layer of monocrystalline silicon can be bonded to the superconducting groundplane and a photoresist layer can be applied to the layer of monocrystalline silicon and the SOI wafer can be etched with the oxygen rich etching plasma, resulting in a monocrystalline silicon top layer with a via that exposes the superconducting groundplane. Then, the fabrication can involve depositing a superconducting surface layer to cover the via.

Denis, Kevin L.↗
NASA NTRS2018

Shock Connectivity and the Late Cycle 24 Solar Energetic Particle Events in July and September 2017

As solar activity steadily declined toward the cycle 24 minimum in the early months of 2017, the expectation for major solar energetic particle (SEP) events diminished with the sunspot number. It was thus surprising (though not unprecedented) when a new, potentially significant active region rotated around the East limb in early July that by midmonth was producing a series of coronal eruptions, reaching a crescendo around 23 July. This series, apparently associated with the birth of a growing pseudostreamer, produced the largest SEP event(s) seen since the solar maximum years. Activity abated with the decay of the active region, but a second episode of magnetic flux emergence in the same area in early September initiated a new round of eruptions. The western longitude of the erupting region, together with its similar coronal setting in both cases, resulted in a set of nearly homologous multipoint SEP event periods at Earth, Solar TErrestrial RElations Observatory-A and Mars (Mars Atmosphere and Volatile EvolutioN) for July and September 2017. We use a combination of WSA-ENLIL-cone heliospheric simulation results, together with SEPMOD SEP event modeling, to illustrate how the event similarities at the three observer sites can be understood from their relative positions and their connectivities to the generated interplanetary shocks.

Luhmann, J. G.↗
NASA NTRS2019

Connections Between the Stratosphere and Surface Weather Associated with the Stratospheric Sudden Warming in Early 2018

A major Stratospheric Sudden Warming (SSW) occurred on 11 February 2018. This was the first major SSW since January 2013 and the first split-vortex SSW since January 2009. We examine the SSW and the tropospheric connections using the NASA MERRA-2 reanalysis (1980-2018) and the NASA GEOS Forward Processing (FP) system. A strong tropospheric wave forcing event in January 2018 displaced the stratospheric vortex off the pole. This displaced vortex persisted until the major SSW vortex split in February. At the time of the major SSW split vortex event the MERRA-2 100 hPa meridional heat flux, a measure of the tropospheric forcing on the stratosphere, attained record high values, associated with a strong tropospheric ridge over the US west coast and wave disturbances over the North Atlantic and Asia. The near-real-time GEOS-FP system forecasted the major SSW event with high skill out to 10 days. The analyses also show that after, the SSW, a steady circulation anomaly persisted over the European sector and the transient weather systems were concentrated over the North American continent, under the stronger of the two split vortices. The propagation of these synoptic-scale vortices around the deep, quasi-stationary vortex that extended from the surface into the stratosphere, is well illustrated in animations of extreme temperature changes near the surface over North America. A quantitative analysis of these synoptic waves and their propagation will examine their signatures in potential vorticity and other fields.

Pawson, S.↗
NASA NTRS2019

WGISS Connected Data Assets Status Report

This report gives the status of the WGISS Connected Data Assets project within the Committee on Earth Observation Satellites (CEOS) Working Group on Information Systems and Services (WGISS).

Enloe, Yonsook↗
NASA NTRS1997

Laboratory Measurements of Sea Ice: Connections to Microwave Remote Sensing

The connections between laboratory measurements and remote sensing observations of sea ice are explored. The focus of this paper is on thin ice which is more easily simulated in a laboratory environment. We summarize results of C-band scatterometer measurements and discuss how they may help in the interpretation of remote sensing data.

remote↗
NASA NTRS2019

Connecting resonant trajectories to a Europa capture through Lissajous staging orbits

The current interest in studying the surface of Europa in search of biosignatures demands efficient strategies in mission design to reach this distant world. An affordable strategy is to use a low energy moon tour, which has natural access to the moon via the L2 gateway. Staging around this libration point allows to decouple the approaching moon tour and the landing trajectory, which enables the option of designing each phase separately. Furthermore, a staging step frees the landing time from the capture phase, adding an additional degree of freedom. Lissajous orbits are the dynamical structures used for these staging orbits. In this paper, the possible ballistic connections between the resonances from the moon tour and Lissajous orbits are studied, including the different geometries that allow for time phasing control.

Anderson, Rodney L.↗
NASA NTRS2021

Global Connections Between El Nino and Landslide Impacts

El Nino is a critical part of global inter-annual climate variability, and the intensity of El Nino has major implications for rainfall-induced natural hazards in many vulnerable countries. The impact of landslides triggered by rainfall is likely to be modulated by the strength of El Nino, but the nature of this connection and the places where it is most relevant remains unconstrained. Here we combine new satellite rainfall data with a global landslide exposure model to show that El Nino has far-reaching effects on landslide impacts to people and infrastructure. We find that the impact of El Nino on landslide exposure can be greater in parts of Southeast Asia and Latin America than that due to seasonal rainfall variability. These findings improve our understanding of hazard variability around the world and can assist disaster mitigation efforts on seasonal timescales.

Robert Emberson↗
NASA NTRS2020

Rapid and Accurate Computation of Invariant Tori, Manifolds, and Connections Near Mean Motion Resonances in the Periodically Perturbed Planar Circular Restricted 3-Body Problem Models

When the planar circular restricted 3-body problem (RTBP) is periodically perturbed, most unstable resonant periodic orbits become invariant tori. In this study, we 1) develop a quasi-Newton method which simultaneously solves for the tori and their center, stable, and unstable directions; 2) implement continuation by both perturbation as well as rotation numbers; 3) compute Fourier-Taylor parameterizations of the stable and unstable manifolds; 4) globalize these manifolds; 5) compute homoclinic and heteroclinic connections. Our methodology improves on efficiency and accuracy compared to prior studies, and applies to a variety of periodic perturbations. We demonstrate the tools on the planar elliptic RTBP.

de la Llave, Rafael↗
NASA NTRS2021

Using GPUs and the Parameterization Method for Rapid Search and Refinement of Connections between Tori in Periodically Perturbed Planar Circular Restricted 3-Body Problems

When the planar circular restricted 3-body problem is periodically perturbed, most unstable periodic orbits become invariant tori. However, 2D Poincare ́ sections no longer work to find their manifolds’ intersections; new methods are needed. In this study, we first review a method of restricting the intersection search to only certain manifold subsets. We then implement this search using Julia and OpenCL, representing the manifolds as triangular meshes and gaining a 30x speedup using GPUs. We finally show how to use manifold parametrizations to refine the ap- proximate connections found in the mesh search. We demonstrate the tools on the planar elliptic RTBP.

de la Llave, Rafael↗
NASA NTRSDate not supplied

Interannual Variability of Aerosols and CO in the Upper Troposphere/Lower Stratosphere (UTLS): Connection to the Climate Variability, Asian Summer Monsoon Strengths, and Emissions

We present our study of decadal variations of UTLS aerosol composition in terms of their sources and convective transport mechanisms associated with the Asian summer monsoon. We use the NASA global model GEOS that incorporates emissions from anthropogenic, biomass burning, volcanic, and other natural sources to simulate the aerosols and related gases, and satellite observations of aerosols and CO in the UTLS from 2010-2020 to investigate (1) the interannual variability of aerosol composition in the UTLS, (2) such variability in relationship to the ENSO and Asian summer monsoon strengths, and (3) the connections of UTLS aerosol with the anthropogenic and natural emissions.

decadal variations↗
NASA NTRS2021

A Geodetic and Positioning Thematic Layer - Identifying tools to connect the GGRF and IGIF

Effective and sustainable modernization of a nation’s geodetic framework relies on the ability of the relevant organizations and other stakeholders to communicate, integrate, and align both their strategic objectives and operational planning with the United Nations Committee of Experts on Global Geospatial Information Management (UN GGIM) Sub-Committee on Geodesy’s (SCoG) roadmap for a Global Geodetic Reference Frame (GGRF) for Sustainable Development. In addition, to implement geodetic modernization initiatives through multiple government agencies, a holistic country action plan (CAP) for geospatial information management must incorporate pertinent geodetic outcomes and outputs. Presently, the CAP framework and principles used by nations is the UN GGIM Integrated Geospatial Information Framework (IGIF). From engagement with geospatial and survey communities across emerging nations in the Asia Pacific region, it is evident more assistance and coordination is necessary to articulate, integrate and connect geodetic organizational strategies with the requirements of the GGRF roadmap; the strategic pathways of the IGIF; and resourcing for a meaningful and relevant multi-faceted CAP. One of the supporting mechanisms for such planning or preparation, which representatives of the International Federation of Surveyors (FIG) Asia Pacific Capacity Development Network (AP CDN) and the UN SCoG Education, Training and Capacity Building (ETCB) working group are considering, is a policy framework and guide for a “Geodetic and Positioning Thematic Layer” (GPTL). Essentially, this “thematic layer”, in terms of the GGRF and IGIF, aims to provide a comprehensive understanding of, and a toolbox for, the “why, what, how, and who” of geodesy and positioning. This discussion paper will provide background and insights for a GPTL dedicated to recognizing, and aligning the geodetic capacity development needs with broader geospatial information management issues and applications. The paper will also outline a rigorous, participatory, and inclusive consultation process for the design and development of a thematic layer. Furthermore, as the intention of the authors is to prepare a forthcoming “white paper” that will concisely describe the issues of a GPTL and initiatives for an appropriate guide and/or policy framework, this paper will seek feedback on: the potential scientific, social, environmental and political benefits of modernizing geodetic infrastructure and systems; the challenges associated with the GGRF roadmap; leveraging the geodesy-relevant elements of each IGIF strategic pathway; the importance of collaborative efforts; and the capacity development needs and resources in relation to governance, technology and people.

SARIB, Rob↗
NASA NTRSDate not supplied

Development of a Virtual Tool to Connect Classrooms to NASA Airborne Science Missions

The NASA Airborne Science Program (ASP) conducts research around the world using various aircraft systems. Researchers have studied monsoons in the Philippines, clouds in Bermuda, fires over the United States, the atmosphere over Antarctica, and so much more. Each of these missions is not only a chance to discover more about our planet, but also to connect students with the scientists making these discoveries. The NASA Airborne Science Mission Tool Suite (MTS) supports NASA flight projects by providing easy to access web-based tools to support planning, communication, and discovery. At its core, MTS links ground science support and flight scientists and provides aircraft situational awareness and visualization of real time data collected during flight. Each mission has different needs, and the basic tools MTS provides are reconfigured for every flight mission. One instance of the MTS, called MTS-Outreach or MTS-O, is being developed and refined to focus on facilitating outreach with students in K-12 schools. As MTS-O continues to be improved and revitalized, versions of it have already been used for group discussions with students in classrooms worldwide. Students using MTS-O can chat with scientists on NASA airborne missions while those scientists fly on the plane and collect data. During the pandemic, this tool was extremely beneficial as in-person classroom visits were not possible. As the tool continues to be refined and developed, we will summarize how it has been used and share its potential applications for the future.

Brenna Crawford Biggs↗