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At least 433 records · Page 24

Genesis Solar Wind – Capture, Return, Curate and Analyze: Looking Backward and Creating a Timeline

Introduction: In 1997 NASA’S Discovery Program selected the Genesis mission proposal to return solar wind samples to Earth for laboratory analyses. Principal Investigator Donald S. Burnett and the science team defined the purity of collector materials and ability to analyze solar wind composition to the precision required for planetary science. As a small mission, focused on a well-defined science goal, yet needing careful attention to engineering details, the communication among scientists and engineers, nurtured by Don Burnett, was exceptional. Genesis Mission and Curation Legacy: Genesis, as the first U. S. spacecraft to return astromaterial samples since Apollo, not only integrated the mission planning and flight teams, but also the science and sample curation teams during the mission development period. Since Genesis is a sample return mission, the Science Team was essential in certifying the collectors (sample containers for solar atoms). From inception, Genesis established mission funding for returned sample curation. JSC was lead in contamination control during mission preparation, including establishment of an ISO 4 cleanroom facility and use of ultrapure water (UPW) for cleaning flight hardware (and, as it turned out, for cleaning collectors after the mishap). Reliable, fast communication among scientists, engineers and curators at the hands-on level established deep respect among team members and efficient decision-making. JSC’s 50-years of astromaterial sample curation provided experienced sample processors onsite during recovery in Utah (a deep bench for emergency response). Post-recovery curation included iterative collaboration with science sample users to clean or verify cleanliness of samples. The science legacy from Genesis is addressed by Burnett and Jurewicz, this volume. In The Beginning: After Apollo sample return, Burnett and Marcia Neugebauer at JPL began discussing a solar wind sample return, with Neugebauer arguing that separate collection of solar wind regimes was essential science. By 1992 a solar wind sample return mission was presented at a workshop, and by 1994 a mission was proposed named Suess-Urey. The mission was re-proposed under a new name GENESIS and selected in 1997. Susan Niebur captured the Genesis mission history and stories, from high level management documents and from many interviews with participants [2]. Her account lets readers glimpse personality of participants in quotations from interviews. Need and Scope for Detailed Technical Timeline: A timeline constructed from lower level task documents has been initiated to document the resources and skills actually used, as well as task sequence or concurrency. Timelines for high level mission events are captured in two documents [1] [2] and for detailed re-entry events in [3]. A detailed technical timeline for Genesis mission and curation activities will provide data points for lower level tasks, such as ISO 4 curation facility construction time, preparation for nominal sample field recovery, mishap recovery, and UPW expansion. Changes in technology context 1990-2024: Semiconductor technologies were easily accessible in the U.S.A. (1990-1999), and the Genesis team used those resources for cleanroom design and UPW system expansion. Image documentation was changing from film to digital during cleanroom construction and payload cleaning (1997-2001). Engineering design was done using computer aided design proprietary software, making more difficult the archiving of payload configuration and materials. Email of documents, tracked delivery service and virtual meeting capability greatly improved communication efficiency. Information sources – Pre-launch mission preparation: Examples of mission science, engineering and contamination control are collector purity testing, payload design/fabrication and ISO 4 cleanroom construction. Information on timing of these activities comes from facility readiness reviews, management reviews, shipping documents, procurement documents, test reports, travel documents, laboratory logs, Quality Assurance documents, dates on images, participant notebooks and emails. Information sources – Sample return re-entry and field recovery activities: Information comes from event timelines produced by Mid-Air Recovery team, Lockheed team lead notes and from chase video, JPL Quality Assurance. Information also comes from images and logbooks from UTTR cleanroom operations and from curatorial documents. Information sources – Resulting science and sample cleaning processes: Agendas from the annual gatherings of the science team initially trace testing for collector purity/cleanliness, and after sample recovery, include collector cleaning and cleanliness assessment. Post-recovery documents include curatorial orders and procedures, sample allocation documents and LPSC abstracts. Timeline Objectives: A simple spreadsheet timeline with headers DATE, EVENT, PEOPLE, COMMENT, INFORMATION SOURCE has been initiated and currently has over 90 entries. While this is not definitive historical research, it is a quick look at the evolution of Genesis curation with pointers to documents or people with information. Engineers for future missions may find useful points of comparison for development of facilities. References:[1] Genesis Mission Reference Document, (2011) JPL D-62382.[2] Niebur S. M., edited by Brown D. W. (2023) NASA’s Discovery Program: The First 20 Years of Competitive Planetary Exploration, NASA-SP-2023-4238.[3] Genesis Mishap Investigation Board Report, Vol. 1 (July 2005).

solar wind↗

Progress on the Autonomous Event Detection System For the Laser Particulate Counter

Field emission is one of the most important issues that limits the performance of the superconducting radio frequency (SRF) systems and leads to SRF cavity trips at the Continuous Electron Beam Accelerator Facility at Jefferson Lab. Studies have confirmed that particulates are the dominant source of field emitters and the particulates can be transported into a cavity from other parts of the accelerator. To monitor the transportation of the particulates, a prototype of a novel, non-invasive laser particulate counter (LPC) has been developed and tested. Experiments have been done to validate the capability of the LPC. We are developing autonomous event detection system to continuously monitor the readout from the LPC and to recognize real events generated by particulates from noises using machine learning model. In this report, we will present how the data are prepared and how the model is trained. We will also discuss the performance of the model.

Zhang, H.↗

Structure and orientations of solar-wind interaction fronts - Pioneer 6.

An analysis is given of five stream-stream interaction events observed in the Pioneer 6 plasma and field data. That the time profiles of all the parameters are consistent among the events and with previous descriptions given in the literature substantiates the notion of a common interaction type. The velocity variations in four of the events tend to lie in planes approximately parallel to the corotation spiral; thus it is implied that the events are reasonably stationary in time in the corotating frame. The data are interpreted in terms of a corotating interaction front, which is a ridge of high pressure parallel to a corotating spiral. The increased pressure is due to radial compression of the streams. The east-west (zonal) flow directions also occur in the front and are shown to be produced by the zonal pressure gradient of the pressure ridge.

Siscoe, G. L.↗

Ions of Jovian origin observed by Voyager 1 and 2 in interplanetary space

Burst-like and long-lived ion fluxes (E greater than 30 keV) of Jovian origin have been observed in interplanetary space by the LECP instrument on the Voyager 1 and 2 spacecraft. Burst (few minute duration) events are observed at distances greater than 0.6 AU from Jupiter. These events are highly anisotropic and possess steep energy spectra, while long-lived (greater than 8 hour duration) events have relatively steady fluxes at low energies, strong anisotropies that decay with time, and a variable high energy component. Both types of events usually display simultaneous onsets and sharp cutoffs for all energies, an excess of atomic number Z not less than 6 particles compared to solar and interplanetary events, and particle flow directions pointed away from Jupiter along the local interplanetary magnetic field. The origin for the long-lived events appears to be inside the bow shock of the planet.

Zwickl, R. D.↗

Design and Analyses of the NSTX-U PF1A Poloidal Field Coil Support

New poloidal field (PF) coils and supports have been designed for the National Spherical Torus Experiment Upgrade (NSTX-U) Recovery project. The PF1A coil structural requirements demand a large preload to pre-compress the coil insulation. Coil support design accounts for all operational conditions and loads of NSTX-U including bakeout, seismic events, and electromagnetic loads. Background magnetic fields produce coil Lorentz forces that react on the structural supports. These Lorentz forces include interactions from the coil current and all plasma events: normal operations, disruptions, and vertical displacement events. This paper will detail the design and design loads and highlight some of the analyses.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

GONG Catalog of Solar Filament Oscillations Near Solar Maximum

We have cataloged 196 filament oscillations from the Global Oscillation Network Group Hα network data during several months near the maximum of solar cycle 24 (2014 January–June). Selected examples from the catalog are described in detail, along with our statistical analyses of all events. Oscillations were classified according to their velocity amplitude: 106 small-amplitude oscillations (SAOs), with velocities <10 km s-1, and 90 large-amplitude oscillations (LAOs), with velocities >10 km s-1. Both SAOs and LAOs are common, with one event of each class every two days on the visible side of the Sun. For nearly half of the events, we identified their apparent trigger. The period distribution has a mean value of 58 ± 15 minutes for both types of oscillations. The distribution of the damping time per period peaks at τ/P = 1.75 and 1.25 for SAOs and LAOs, respectively. We confirmed that LAO damping rates depend nonlinearly on the oscillation velocity. The angle between the direction of motion and the filament spine has a distribution centered at 27° for all filament types. This angle agrees with the observed direction of filament-channel magnetic fields, indicating that most of the cataloged events are longitudinal (i.e., undergo field-aligned motions). We applied seismology to determine the average radius of curvature in the magnetic dips, R ≈ 89 Mm, and the average minimum magnetic field strength, B ≈ 16 G. The catalog is available to the community online and is intended to be expanded to cover at least 1 solar cycle.

Filaments↗

Storm-associated Pc 5 micropulsation events observed at the synchronous equatorial orbit.

Quasi-sinusoidal magnetic-field (micropulsations) are regularly observed at ATS 1 during geomagnetic storms. The wave events typically occur during the main phase and tend to be confined to the afternoon sector. All observed events have been closely correlated with magnetospheric substorm activity. Power spectral analysis shows that the observed oscillations are composed of harmonically related components. Twenty-six wave events were observed in 1967; the analysis of three typical Pc 5 events is presented here. The observations are compared with the predictions of theory for a hot inhomogeneous plasma. It is suggested that the observed micropulsations can be understood as the occurrence of either an Alfven wave instability, or a drift instability, of the enhanced storm-time ring current.

Barfield, J. N.↗

Spatially resolved microlensing time-scale distributions across the Galactic bulge with the VVV survey

ABSTRACT We analyse 1602 microlensing events found in the VISTA Variables in the Via Lactea (VVV) near-infrared (NIR) survey data. We obtain spatially resolved, efficiency-corrected time-scale distributions across the Galactic bulge (|ℓ| < 10°, |b| < 5°), using a Bayesian hierarchical model. Spatially resolved peaks and means of the time-scale distributions, along with their marginal distributions in strips of longitude and latitude, are in agreement at a 1σ level with predictions based on the Besançon model of the Galaxy. We find that the event time-scales in the central bulge fields (|ℓ| < 5°) are on average shorter than the non-central (|ℓ| > 5°) fields, with the average peak of the lognormal time-scale distribution at 23.6 ± 1.9 d for the central fields and 29.0 ± 3.0 d for the non-central fields. Our ability to probe the structure of the bulge with this sample of NIR microlensing events is limited by the VVV survey’s sparse cadence and relatively small number of detected microlensing events compared to dedicated optical surveys. Looking forward to future surveys, we investigate the capability of the Roman telescope to detect spatially resolved asymmetries in the time-scale distributions. We propose two pairs of Roman fields, centred on (ℓ = ±9, 5°, b = −0.125°) and (ℓ = −5°, b = ±1.375°) as good targets to measure the asymmetry in longitude and latitude, respectively.

79 ASTRONOMY AND ASTROPHYSICS↗

Evidence for solar magnetic loops beyond 1 AU

A description is presented of observations of energetic particles emitted by solar flares into interplanetary magnetic loop-like structures during two different events. In one of these events, the IMP-7 spacecraft detected particles which were injected into an apparently preexisting 'magnetic loop' during the onset of a solar flare particle event. The energetic particles appear to bounce between two magnetic mirrors. During the second event, the spacecraft entered a magnetic field regime where the energetic particle intensities had already reached a characteristic angular distribution indicative of a stably trapped population. Observations of the evolution of the angular distributions of the energetic particle intensities during the solar events reveal the occurrence of unusual particle anisotropies.

Sarris, E. T.↗

Learning-Based Real-Time Event Identification Using Rich Real PMU Data

A large-scale deployment of phasor measurement units (PMUs) that reveal the inherent physical laws of power systems from a data perspective enables an enhanced awareness of power system operation. However, the high-granularity and non-stationary nature of PMU data and imperfect data quality could bring great technical challenges for real-time system event identification. To address these challenges, this paper proposes a two-stage learning-based framework. In the first stage, a Markov transition field (MTF) algorithm is exploited to extract the latent data features by encoding temporal dependency and transition statistics of PMU data in graphs. Then, a spatial pyramid pooling (SPP)-aided convolutional neural network (CNN) is established to efficiently and accurately identify power events. The proposed method fully builds on and is also tested on a large real-world dataset from several tens of PMU sources (and the corresponding event logs), located across the U.S., with a time span of two consecutive years. We report the numerical results validate that our method has high identification accuracy while showing good robustness against poor data quality.

24 POWER TRANSMISSION AND DISTRIBUTION↗

Hydromagnetic vortices. I - The 11 December 1977 event

Through a synthesis of magnetometer, plasma, energetic particle and electric field data from the ISEE satellite pair, the characteristics of the initial (11 December 1977) magnetotail plasma vortex event reported by Hones et al. (1978), are described. The event is associated with a hot (beta is approximately unity) compressional hydromagnetic wave and apparent vortical motion is seen because at two points in the flow cycle the flow is field-aligned. The behavior of the energetic ions receives special study: when combined with the thermal flow measurements energy dispersion is evident in the field-aligned flow, while the large pitch angle energetic ions reveal the presence of gradients. It is argued that these gradients are wave-induced, and the data are used to determine the perpendicular wave wavelength together with the speed and direction of transverse wave propagation.

Saunders, M. A.↗

Tuning water dissociation at oxide–electrolyte interfaces with electric fields

Understanding how electric fields influence water dissociation at heterogeneous interfaces is crucial for controlling interfacial chemical reactions and advancing next-generation energy technologies. Herein, ab initio–based machine learning simulations show that even small electric field changes can significantly alter the water dissociation fraction at planar TiO 2 –electrolyte interfaces. The resulting free energy difference between undissociated and dissociated interfacial water exhibits a linear dependence on the field change with a slope of 1.97 eÅ, which far exceeds the dissociation-induced dipole change of a water molecule. Employing a machine-learned collective variable to investigate the reaction statistics of thousands of water dissociation/recombination events, we find that small electric field changes exert minor effects on individual reaction energy barriers but significantly influence the populations of local configurations associated with initial states that are most favorable for reactions. These findings elucidate the pronounced impact of electric fields on interfacial water dissociation and reveal a mechanism for electric-field-controlled chemical reactions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Development and Analysis of a Thick Cloud Layers Database for Lightning Launch Commit Criteria Improvement

Lightning can pose a potential threat to space launch vehicles. In response to this, rules were created called the Lightning Launch Commit Criteria (LLCC) that help weather personnel evaluate the potential for natural and rocket-triggered lightning. One of the ten LLCC with the least research is called the Thick Cloud Layers rule. To further understand electrification of thick cloud layers and potentially improve the Thick Cloud Layers rule, a database of thick cloud layers that occurred over the Eastern Range was created. This database is then used to create an algorithm for identifying and differentiating thick cloud layers from other cloud types based on radar characteristics, temperature levels in reference to cloud height, and the surface electric field. By analyzing and identifying thick cloud events, this project could help narrow down when thick clouds are occurring and potentially minimize unnecessary launch delays. Events that caused LLCC violations involving the Thick Cloud Layers rule were analyzed by hand using Level-2 NEXRAD radar data from the National Weather Service WSR-88D radar in Melbourne with the program GR2Analyst. Cases that were found to be isolated and not involved with convection were recorded (date, start/end time, location) in a database. Radar data associated with these cases was collected and gridded using Python radar packages. Once gridded, I calculated and recorded for each radar scan the following radar reflectivity driven parameters within an 11x11 km bin centered on each 1 square km grid point: the mean reflectivity colder than 0 degrees Celsius, Maximum Radar Reflectivity (MRR) colder than 0 degrees Celsius, Volume Averaged Height Integrated Radar Reflectivity (VAHIRR), Hydrometeor Identification (HID), the difference between the maximum and mean reflectivity, the cloud depth colder than 0 degrees Celsius, the overall cloud depth, the cloud top, and the cloud bottom. Soundings for each event were used to determine cloud temperature levels, and where the cloud is in relation to the freezing level. Electric field mill data collected over the Eastern Range was used to determine surface electric fields below each cloud. All parameters were analyzed in depth for several thick cloud cases to gain an understanding of typical thick cloud characteristics. Cases of thick clouds and other isolated cloud types were also recorded for training purposes to see if enough differences exist between cloud types to differentiate them with an algorithm. Each case along with its corresponding characteristics was recorded in a database, and this database was used to compare differing cloud types, as well as train the algorithm to detect thick clouds.

Lightning↗

Primary Disaster Field Office (DFO), Lufkin, Texas

On February 1, 2003, the Space Shuttle Columbia broke apart during atmospheric re-entry on mission STS-107; the complexity of such an event cannot be underestimated. The Lufkin Disaster Field Office (DFO) served as the primary DFO for all operations, including staging assets and deploying field teams for search, recovery and security. There were many organizations that had operational experience with disaster recovery. Offers to help came from many groups including the White House Liaison Office, the Department of Defense (DOD), branches of local, state and federal government, the Federal Bureau of Investigation (FBI), the Federal Emergency Management Agency (FEMA), the Environmental Protection Agency (EPA), state police, fire departments, the Texas Forestry Service, the Texas Army National Guard, medical groups, various rescue forces, contractor companies, the Salvation Army, local businesses, and citizens of our country and especially East Texas. The challenge was to know how much help to accept and how to efficiently incorporate their valuable assistance into a comprehensive and cohesive operational plan. There were more than 2,000 people involved with search and recovery.

Wetherbee, James D.↗

Three-dimensional magnetic reconnection and the magnetic topology of coronal mass ejection events

Measurements of superthermal electron fluxes in the solar wind indicate that field lines within coronal mass ejections, CMEs, near and beyond 1 AU are normally connected to the Sun at both ends. However, on occasion some field lines embedded deep within CMEs appear to be connected to the Sun at only one end. Here we propose an explanation for how such field lines arise in terms of 3-dimensional reconnection close to the Sun. Such reconnection also provides a natural explanation for the flux rope topology characteristic of many CMEs as well as the coronal loops formed during long-duration, solar X-ray events. Our consideration of the field topologies resulting from 3-dimensional reconnection indicates that field lines within and near CMEs may on occasion be connected to the outer heliosphere at both ends.

Gosling, J. T.↗

Westward equatorial electrojet during daytime hours

The phenomenon of the depression of the geomagnetic horizontal field during the daytime hours of magnetically quiet days at equatorial stations is described. These events are generally seen around 0700 and 1600 LT, being more frequent during the evening than the morning hours. The evening events are more frequent during periods of low solar activity and in the longitude region of weak equatorial electrojet currents. The latitudinal extent of the phenomenon is limited to the normal equatorial electrojet region, and on some occasions the phenomenon is not seen at both stations, separated by only a few hours in longitude. During such an event, the latitudinal profile of the geomagnetic vertical field across the equator is reversed, the ionospheric drift near the equator is reversed toward the east, the q type of sporadic E layer is completely absent, and the height of the peak ionization in the F2 region is decreased. It is suggested that these effects are caused by a narrow band of current flowing westward in the E region of the ionosphere and within the latitude region of the normal equatorial electrojet, due to the reversal of the east-west electrostatic field at low latitudes.

Rastogi, R. G.↗

The evolution of Ertel's potential vorticity during stratospheric sudden warmings

In the winter stratosphere of the Northern Hemisphere, the disruption of the westerly vortex and associated warming of polar latitudes is a well known phenomenon. It has become apparent that some important dynamical processes in the stratosphere are highly nonlinear and are best thought of locally rather than in terms of the interaction between the zonal-mean flow and harmonic waves around latitude circles. The importance of nonlinear processes was suggested by McIntyre and Palmer (1983, 1984) who used isentropic maps of Ertel's Potential Vorticity to show that during disturbed episodes material lines may become strongly and irreversibly deformed in certain places. They adopted the term planetary wave breaking to describe this process. Isentropic maps of Q are used to follow the evolution of a Canadian warming in November - December 1981 and a particularly strong warming in January 1982. The advection of Q over large distances on isentropic surfaces was a striking feature of the flow during each event. This could be identified because of our ability to follow the movement of material lines due to the approximate conservation of Q over several days. The advection of Q was a nonlinear process because its changing distribution affected the advecting wind field. The Canadian warming did not lead to a permanent change in the structure of the westerly vortex, as defined by the coarse-grain field of Q, whereas the January event was accompanied by a substantial loss of resolved Q which was never fully recovered.

Fairlie, T. D. A.↗

Origin of interplanetary southward magnetic fields responsible for major magnetic storms near solar maximum (1978-1979)

Simultaneous ISEE-3 field and plasma data were used to examine interplanetary phenomena associated with 10 major magnetic storms detected from August 16, 1978, to December 28, 1979, in a study of Gonzalez and Tsurutani (1987), and, in particular to determine the origins of the southward magnetic fields which caused the storms. In nine of the 10 cases, the responsible interplanetary events were found, as expected, to be associated with the high magnetic fields in the stream-stream interaction regions (sheaths) or driver gases, with the events following the interplanetary shocks. The tenth event was found to be associated not with a high-speed stream, but with a noncompressional density-enhancement event. The results of this study indicate the equal importance of both the sheath fields or draped fields and the driver gas fields for the generation of major geomagnetic storms.

Tsurutani, Bruce T.↗