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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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A CME-Producing Solar Eruption from the Interior of a Twisted, Emerging Bipole
In a negative-polarity coronal hole, magnetic flux emergence, seen by the Solar Dynamics Observatory's (SDO) Helioseismic Magnetic Imager (HMI), begins at approximately 19:00 UT on March 3, 2016. The emerged magnetic field produced sunspots with penumbrae by 3:00 UT on March 4, which are a part of NOAA 12514. The emerging magnetic field is largely bipolar with the opposite-polarity fluxes spreading apart overall, but there is simultaneously some convergence and cancellation of opposite-polarity flux at the polarity inversion line (PIL) inside the emerging bipole. The emerging bipole shows obvious overall left-handed shear and/or twist in its magnetic field and corresponding clockwise rotation of the two poles of the bipole about each other as the bipole emerges. The eruption comes from inside the emerging bipole and blows it open to produce a CME observed by SOHO/LASCO. That eruption is preceded by flux cancellation at the emerging bipole's interior PIL, cancellation that plausibly builds a sheared and twisted flux rope above the interior PIL and fnally triggers the blow-out eruption of the flux rope via photospheric-convection-driven, slow tether-cutting reconnection of the legs of the sheared core field, low above the interior PIL, as proposed by van Ballegooijen and Martens (1989, ApJ, 343, 971) and Moore and Roumeliotis (1992, in Eruptive Solar Flares, ed. Z. Svestka, B.V. Jackson, and M.E. Machado [Berlin:Springer], 69). The production of this eruption is a (perhaps rare) counterexample to solar eruptions that result from external collisional shearing between opposite polarities from two distinct emerging and/or emerged bipoles (Chintzoglou et al., 2019, ApJ, 871:67).
A Two-sided-Loop X-Ray Solar Coronal Jet and a Sudden Photospheric Magnetic-field Change, Both Driven by a Minifilament Eruption
Most of the commonly discussed solar coronal jets are of the type consisting of a single spire extending approximately vertically from near the solar surface into the corona. Recent research of a substantial number of events shows that eruption of a miniature filament (minifilament) drives at least many such single-spire jets, and concurrently generates a miniflare at the eruption site. A different type of coronal jet, identified in X-ray images during the Yohkoh era, are two-sided-loop jets, which extend from a central excitation location in opposite directions, along two opposite low-lying coronal loops that are more-or-less horizontal to the surface. We observe such a two-sided-loop jet from the edge of active region (AR) 12473, using data from Hinode XRT and EIS, and SDO AIA and HMI. Similar to single-spire jets, this two-sided-loop jet results from eruption of a minifilament, which accelerates to over 140 km/s before abruptly stopping upon striking overlying nearlyhorizontal magnetic field at ∼30,000 km altitude and producing the two-sided-loop jet via interchange reconnection. Analysis of EIS raster scans show that a hot brightening, consistent with a small flare, develops in the aftermath of the eruption, and that Doppler motions (∼40 km/s) occur near the jet-formation region. As with many single-spire jets, the trigger of the eruption here is apparently magnetic flux cancelation, which occurs at a rate of ∼4×10^18 Mx/hr, comparable to the rate observed in some single-spire AR jets. This example of a two-sided jet, along with numerous examples of single-spire jets, supports that essentially all coronal jets result from eruptions of minifiaments, and frequently the eruption of the minifilment is triggered by magnetic flux cancelation. (Details are in Sterling et al. 2019, ApJ, 871, 220.)
Applying the NASA SPoRT R2O/O2R Paradigm to Space Weather: MAG4 Applications and Assessment at SWPC
No abstract available
SISO Space Reference FOM - Tools and Testing
The Simulation Interoperability Standards Organization (SISO) Space Reference Federation Object Model (SpaceFOM) version 1.0 is nearing completion. Earlier papers have described the use of the High Level Architecture (HLA) in Space simulation as well as technical aspects of the SpaceFOM. This paper takes a look at different SpaceFOM tools and how they were used during the development and testing of the standard.The first organizations to develop SpaceFOM-compliant federates for SpaceFOM development and testing were NASA's Johnson Space Center (JSC), the University of Calabria (UNICAL), and Pitch Technologies.JSC is one of NASA's lead centers for human space flight. Much of the core distributed simulation technology development, specifically associated with the SpaceFOM, is done by the NASA Exploration Systems Simulations (NExSyS) team. One of NASA's principal simulation development tools is the Trick Simulation Environment. NASA's NExSyS team has been modifying and using Trick and TrickHLA to help develop and test the SpaceFOM.The System Modeling And Simulation Hub Laboratory (SMASH-Lab) at UNICAL has developed the Simulation Exploration Experience (SEE) HLA Starter kit, that has been used by most SEE teams involved in the distributed simulation of a Moon base. It is particularly useful for the development of federates that are compatible with the SpaceFOM. The HLA Starter Kit is a Java based tool that provides a well-structured framework to simplify the formulation, generation, and execution of SpaceFOM-compliant federates.Pitch Technologies, a company specializing in distributed simulation, is utilizing a number of their existing HLA tools to support development and testing of the SpaceFOM. In addition to the existing tools, Pitch has developed a few SpaceFOM specific federates: Space Master for managing the initialization, execution and pacing of any SpaceFOM federation; EarthEnvironment, a simple Root Reference Publisher; and Space Monitor, a graphical tool for monitoring reference frames and physical entities.Early testing of the SpaceFOM was carried out in the SEE university outreach program, initiated in SISO. Students were given a subset of the FOM, that was later extended. Sample federates were developed and frameworks were developed or adapted to the early FOM versions.As drafts of the standard matured, testing was performed using federates from government, industry, and academia. By mixing federates developed by different teams the standard could be tested with respect to functional correctness, robustness and clarity.These frameworks and federates have been useful when testing and verifying the design of the standard. In addition to this, they have since formed a starting point for developing SpaceFOM-compliant federations in several projects, for example for NASA, ESA as well as SEE.
Lynx X-Ray Observatory: An Overview
Lynx, one of the four strategic mission concepts under study for the 2020 Astrophysics Decadal Survey, provides leaps in capability over previous and planned x-ray missions and provides synergistic observations in the 2030s to a multitude of space- and ground-based observatories across all wavelengths. Lynx provides orders of magnitude improvement in sensitivity, on-axis subarcsecond imaging with arcsecond angular resolution over a large field of view, and high-resolution spectroscopy for point-like and extended sources in the 0.2- to 10-keV range. The Lynx architecture enables a broad range of unique and compelling science to be carried out mainly through a General Observer Program. This program is envisioned to include detecting the very first seed black holes, revealing the high-energy drivers of galaxy formation and evolution, and characterizing the mechanisms that govern stellar evolution and stellar ecosystems. The Lynx optics and science instruments are carefully designed to optimize the science capability and, when combined, form an exciting architecture that utilizes relatively mature technologies for a cost that is compatible with the projected NASA Astrophysics budget.
Overview of Coronal Jets, and Jet Connections to Other Solar Features
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Aerocapture as an Enhancing Option for Ice Giants Missions
Investigation of Uranus and Neptune, via orbiter and atmospheric probes, is required to answer pressing science questions that have been raised in previous Decadal Surveys. As the Ice Giants are the farthest planets from Earth, traditional fully-propulsive orbit insertion missions would require a large amount of propellant, leaving less mass for the scientific payload; additionally, transit time to the planetary bodies near 13-15 years. Aerocapture uses aerodynamic forces generated by flight within a planetary atmosphere to decelerate and achieve orbit insertion. Although, aerocapture has not been used in the past, recent developments in thermal protection systems, guidance and control, and navigation capabilities enable the use of rigid, heritage entry vehicle configurations already flown at other planetary bodies for Ice Giants aerocapture. With the addition of these recent capabilities, aerocapture can robustly deliver spacecraft to Ice Giant orbits, while substantially increasing on-orbit payload mass (more than 40%) and reducing the transit time by 2-5 years (15-30%) relative to fully-propulsive orbit insertion.
Iteratively Improving Experimental Products: MAG4's Updates at SRAG Using the NASA SPoRT Paradigm
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MAG4 Forecasts Major Flares, CMEs, and SPEs Using a Free-Energy Proxy
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US Contributions to the Athena Wide Field Imager
The world’s premier X-ray astronomical observatories, Chandra and XMM-Newton, have been operating for about 20 years. The next flagship X-ray observatory launched will be ESA’s Athena mission. We discuss planned US contributions to the Athena Wide Field Imager instrument, which encompass transient source detection, background characterization and reduction, and detector electronics design and testing, in addition to scientific contributions.
Arcus: The Soft X-ray Grating Explorer
Arcus provides high-resolution soft X-ray spectroscopy in the 12-50 Å bandpass with unprecedented sensitivity, including spectral resolution > 2500 and effective area > 250 cm2. The three top science goals for Arcus are (1) to measure the effects of structure formation imprinted upon the hot baryons that are predicted to lie in extended halos around galaxies, (2) to trace the propagation of outflowing mass, energy, and momentum from the vicinity of the black hole to extragalactic scales as a measure of their feedback, and (3) to explore how stars form and evolve. Arcus uses the same 12 m focal length grazing-incidence Silicon Pore X-ray Optics (SPOs) that ESA has developed for the Athena mission; the focal length is achieved on orbit via an extendable optical bench. The focused X-rays from these optics are diffracted by high-efficiency Critical-Angle Transmission (CAT) gratings, and the results are imaged with flight-proven CCD detectors and electronics. Combined with the high-heritage NGIS LEOStar-2 spacecraft and launched into 4:1 lunar resonant orbit, Arcus provides high sensitivity and high efficiency observing of a wide range of astrophysical sources.
The MAG4 Flare Forecast Tool and Iterative O2R2O
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The Berkeley Sample of Type II Supernovae: BVRI Light Curves and Spectroscopy of 55 SNe II
In this work, BVRI light curves of 55 Type II supernovae (SNe II) from the Lick Observatory Supernova Search programme obtained with the Katzman Automatic Imaging Telescope and the 1 m Nickel telescope from 2006 to 2018 are presented. Additionally, more than 150 spectra gathered with the 3 m Shane telescope are published. We conduct an analyse of the peak absolute magnitudes, decline rates, and time durations of different phases of the light and colour curves. Typically, our light curves are sampled with a median cadence of 5.5 d for a total of 5093 photometric points. In average, V-band plateau declines with a rate of 1.29 mag (100 d)(exp −1), which is consistent with previously published samples. For each band, the plateau slope correlates with the plateau length and the absolute peak magnitude: SNe II with steeper decline have shorter plateau duration and are brighter. A time-evolution analysis of spectral lines in term of velocities and pseudo-equivalent widths is also presented in this paper. Our spectroscopic sample ranges between 1 and 200 d post-explosion and has a median ejecta expansion velocity at 50 d post-explosion of 6500 km s(exp −1) (H α line) and a standard dispersion of 2000 km s(exp −1). Nebular spectra are in good agreement with theoretical models using a progenitor star having a mass <16M⨀. All the data are available to the community and will help to understand SN II diversity better, and therefore to improve their utility as cosmological distance indicators.
X-ray Spectra and Multiwavelength Machine Learning Classification for Likely Counterparts toFermi3FGL Unassociated Sources
We conduct X-ray spectral fits on 184 likely counterparts to Fermi-LAT 3FGL unassociated sources. Characterization and classification of these sources allows for more complete population studies of the high-energy sky. Most of these X-ray spectra are well fit by an absorbed power law model, as expected for a population dominated by blazars and pulsars. A small subset of 7 X-ray sources ave spectra unlike the power law expected from a blazar or pulsar and may be linked to coincident stars or background emission. We develop a multiwavelength machine learning classifier to categorize unassociated sources into pulsars and blazars using gamma- and X-ray observations. Training a random forest procedure with known pulsars and blazars, we achieve a cross-validated classification accuracy of 98.6%. Applying the random forest routine to the unassociated sources returned 126 likely blazar candidates (defined as P(bzr) ≥ 90%) and 5 likely pulsar candidates (P(bzr) ≤ 10%). Our new X-ray spectral analysis does not drastically alter the random forest classifications of these sources compared to previous works, but it builds a more robust classification scheme and highlights the importance of X-ray spectral fitting. Our procedure can be further expanded with UV, visual, or radio spectral parameters or by measuring flux variability.
SpaceFOM: An Interoperability Standard for Space Systems Simulations
There is a long history of simulation supporting space systems development. This includes relatively simple parametric simulations to more complex trajectory simulations to large scale integrated vehicle simulation. One area of relatively recent development is in the area of distributed or interoperable simulation. Distributed simulation has been in wide use by the US military for years but is being used more widely in the aerospace community. To support large scale distributed simulation, the military community has developed a number of standards to support a priori interoperability between large collections of disparate simulation. For example, the IEEE 1516 High Level Architecture (HLA) and the Real-time Platform Reference Federation Object Model (RPR FOM). While HLA is suitable for space systems, there are a number of design decisions made in the development of the RPR FOM that prevent it from working well for space applications. In order to address these deficiencies, the Simulation Interoperability Standards Organization (SISO) developed a new HLS-compatible interoperability standard to support the needs of complex space systems. This standard is the Space Reference Federation Object Model (SpaceFOM). This paper presents on overview of the SpaceFOM including the fundamentals of the SpaceFOM, the key features of the SpaceFOM, and how the SpaceFOM supports large scale distributed simulation of complex space systems.
SpaceFOM: An Interoperability Standard for Space Systems Simulations
There is a long history of simulation supporting space systems development. This includes relatively simple parametric simulations to more complex trajectory simulations to large scale integrated vehicle simulation. One area of relatively recent development is in the area of distributed or interoperable simulation. Distributed simulation has been in wide use by the US military for years but is being used more broadly in the aerospace community. To support large scale distributed simulation, the military community has developed a number of standards to support a-priori interoperability between large collections of disparate simulations. For example, the IEEE 1516 High Level Architecture (HLA) and the Real-time Platform Reference Federation Object Model (RPR FOM). While HLA is suitable for space systems, there are a number of design decisions made in the development of the RPR FOM that prevent it from working well for space applications. In order to address these deficiencies, the Simulation Interoperability Standards Organization (SISO) developed a new HLA-based interoperability standard to support the needs of complex space systems. This standard is the Space Reference Federation Object Model (SpaceFOM). This paper presents an overview of the SpaceFOM including the fundamentals of the SpaceFOM, the key features of the SpaceFOM, and how the SpaceFOM supports large scale distributed simulation of complex space systems.