Investigation of structural properties of fiber-glass filament-wound pressure vessels at cryogenic temperatures
Structural properties of fiberglass filament wound pressure vessels at cryogenic temperatures
FIBER↗
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A perturbation calculation of the dynamical effects of cosmic rays and interstellar gas on the solar wind
The modulation of galactic cosmic rays and other energetic particles by the solar wind produces a gradient in their pressure, which in turn influences the wind dynamics. The basic equations describing this interaction are presented in the 'hydrodynamic' approximation. A perturbation solution of the equations is presented for the case in which both the galactic cosmic ray pressure, and the pressure of the anomalous cosmic ray component accelerated at the wind termination shock, are small compared with the wind ram pressure. Analytical expressions for the deceleration of the wind and the modification of the shock and its location are derived in this case. These effects are estimated to have a relative magnitude of several percent in the solar wind. The interstellar neutral gas which penetrates the heliosphere is ionized, predominantly by photoionization and charge exchange with the wind, and may also have a significant dynamical effect on the wind. The basic equations describing this interaction are also presented, A perturbation solution is presented under the assumption that the mass loading and momentum-loading of the wind by the interstellar pickup ions is small compared with the wind ram pressure. Analytical expressions for the deceleration of the wind, the contribution of the pickup ions to the wind pressure, and the modification of the termination shock location are derived. Again, with the exception of pickup ion pressure which is large compared with solar wind thermal pressure, the effects are estimated to be several percent in relative magnitude in the solar wind.
Lee, M. A.↗
Solar Energetic Proton Access to the Inner Magnetosphere During the September 7–8, 2017 Event
Here, the access of solar energetic protons into the inner magnetosphere on September 7–8, 2017 is investigated by following reversed proton trajectories to compute the proton cutoff energy using the Dartmouth geomagnetic cutoff code (Kress et al., 2010, https://doi.org/10.1029/2009sw000488). The cutoff energies for protons coming from the west and east direction, the minimum and maximum cutoff energy respectively, are calculated every 5 min along the orbit of Van Allen Probes using TS07 and the Lyon-Fedder-Mobarry (LFM) MHD magnetic field model. The result shows that the cutoff energy increases significantly as the radial distance decreases, and that the cutoff energy decreases with the building up of the ring current during magnetic storms. Solar wind dynamic pressure also affects cutoff suppression (Kress et al., 2004, https://doi.org/10.1029/2003gl018599). The LFM-RCM model shows stronger suppression of cutoff energy than TS07 during strong solar wind driving conditions. The simulation result is compared with proton flux measurements, showing consistent variation of the cutoff location during the September 7–8, 2017 geomagnetic storm.
79 ASTRONOMY AND ASTROPHYSICS↗
Lidar Measurements and High-Resolution Mesoscale Modeling of Coastally Trapped Disturbances off the Coast of California
Coastally Trapped disturbances (CTDs) are shifts in wind direction from the pre-dominant direction to equatorward to poleward for a period of time. These CTDs occur during the warm season off the California coast and impact coastal weather conditions and planned offshore wind plants. This study assesses the characteristics of CTD events as observed by lidar and other offshore buoys, then evaluates the ability of modeling systems to capture the correct characteristics, leveraging model output from the High-Resolution Rapid Refresh (HRRR) operational modeling system and the NOW-23 (National Offshore Wind) model dataset. CTDs were analyzed for October 2020 and May through to October of 2021, identifying 18 unique CTD events, confirmed by a nearby National Data Buoy Center (NDBC) buoy. The HRRR model captured most of these events, but the NOW-23 model output contained only 12 events. Composites of the wind, temperature, and pressure perturbations pre-, during, and post-event demonstrated the diminishment in wind speed, particularly for the alongshore component. Although the NOW-23 model captured the alongshore wind component and pressure perturbations well, the cross-shore wind component and temperature perturbations varied substantially. When the turbulent kinetic energy deviation and wind shear was positive across all levels pre-event, the NOW-23 modeling system was less likely to capture the CTD event. In contrast, the events that were captured by the model tended to have negative wind shear aloft pre-event.
coastal meteorology↗
Filament-overwrapped metallic cylindrical pressure vessels.
Filament overwrapped metallic cylindrical pressure vessels show greater efficiency ratio and buckling strength
COMPRESSION BUCKLING↗
A post-Pioneer Venus reassessment of the Martian dayside ionosphere as observed by radio occultation methods
Global characteristics of the dayside ionosphere of Mars were investigated by reanalyzing the electron-density dayside altitude profiles obtained by Mariners 4, 6, 7, and 9 and the Viking 1 and 2. The properties of both the electron density peaks and the topside profiles with the behavior expected for a Chapman layer in the Mars ionosphere were compared with those observed at Venus with the Pioneer Venus. The results yield an improved picture of the solar zenith angle dependences of both the peaks and the scale heights of the ionosphere of Mars, and their comparison with Venus at solar minimum. It is shown that, under similar conditions where the incident solar wind dynamic pressure exceeds the peak ionospheric thermal pressure, the Martian dayside ionosphere peaks at higher altitudes in the flanks and has a greater scale height. Thus, Martian and Venusian ionospheres would present different obstacles to solar wind.
Zhang, M. H. G.↗
A monochromatic gravity wave observed by the Flatland Atmospheric Observatory
On 21 December 1991 from approximately 1300 to approximately 1600 UTC a monochromatic wave train with an 8.2-min period was observed by the suite of instruments at the Flatland Atmospheric Observatory (FAO), located in very flat terrain near Champaign-Urbana, Illinois. A 915-MHz radar measured the vertical wind velocity w every 60 s from 0.55 km MSL (0.34 km AGL) to approximately 3 km with 250-m range gates, and a 50-MHz radar measured the oblique wind in four directions, as well as w, every 130 s from 2.75 to approximately 7.25 km with 750-m range gates. A meteorological ground station measured the surface pressure P, wind speed vector u and azimuth alpha, temperature, solar insolation, etc., every 30 s. P was also measured every 120 s by six digital barograph stations within 30 km of Flatland. Using the hodograph of surface vector u and alpha and the impedance relation, we estimated the azimuthal direction of propagation phi to be 45 deg +/- 15 deg clockwise from north, the intrinsic and apparent horizontal phase speeds C(sub i) and C(sub o), respectively, (which are about equal since the direction of propagation is about normal to the mean wind) to be 21 +/- 5 m/s, and the horizontal wavelength lambda to be 10.0 +/- 2.5 km. The peak-to-peak surface horizontal perturbation velocity varied from approximately 2 to 5 m/s from cycle to cycle.
Vanzandt, T. E.↗
Exterior and Interior Polar Cusps: Observations from Hawkeye
Hawkeye plasma, magnetic field, and plasma wave instruments directly sampled the throat of the northern polar cusp as the orientation of the Interplanetary Magnetic Field (IMF) changed from southward to northward on July 3, 1974. Two distinct regions in the polar cusp were identified based on magnetic field, plasma flow and magnetic and electric noise: the interior and exterior cusps. The observations show highly variable flows in the exterior portion of the cusp and constantly strong dawn-dusk flows in the interior portion during periods of strong IMF By component. Results of a minimum variance analysis of the magnetic field at each cusp interface crossing provides evidence that the magnetopause surface normal deviated highly from empirical models. During intervals of relatively steady solar wind dynamic pressure, the motion of the cusp relative to the slow moving spacecraft was modulated by the varying IMF clock angle as observed by IMP 8 in the upstream solar wind. The motion did not show a correlation with internal processes monitored by the A E index. We propose that observed plasma flow patterns and cusp motion are results of reconnection between the IMF and the magnetospheric magnetic field. Flow velocity observed in the interior cusp is consistent with stress balance for a reconnection process. This unique interval provides an opportunity for detailed studies of the plasma, magnetic field, and plasma wave properties in both the exterior and interior cusp.
Chen, S.-H.↗
Central Plasma Sheet Ion Properties as Inferred from Ionospheric Observations
A method of inferring central plasma sheet (CPS) temperature, density, and pressure from ionospheric observations is developed. The advantage of this method over in situ measurements is that the CPS can be studied in its entirely, rather than only in fragments. As a result, for the first time, comprehensive two-dimensional equatorial maps of CPS pressure, density, and temperature within the isotropic plasma sheet are produced. These particle properties are calculated from data taken by the Special Sensor for Precipitating Particles, version 4 (SSJ4) particle instruments onboard DMSP F8, F9, F10, and F11 satellites during the entire year of 1992. Ion spectra occurring in conjunction with electron acceleration events are specifically excluded. Because of the variability of magnetotail stretching, the mapping to the plasma sheet is done using a modified Tsyganenko [1989] magnetic field model (T89) adjusted to agree with the actual magnetotail stretch at observation time. The latter is inferred with a high degree of accuracy (correlation coefficient -0.9) from the latitude of the DMSP b2i boundary (equivalent to the ion isotropy boundary). The results show that temperature, pressure, and density all exhibit dawn-dusk asymmetries unresolved with previous measurements. The ion temperature peaks near the midnight meridian. This peak, which has been associated with bursty bulk flow events, widens in the Y direction with increased activity. The temperature is higher at dusk than at dawn, and this asymmetry increases with decreasing distance from the Earth. In contrast, the density is higher at dawn than at dusk, and there appears to be a density enhancement in the low-latitude boundary layer regions which increases with decreasing magnetic activity. In the near-Earth regions, the pressure is higher at dusk than at dawn, but this asymmetry weakens with increasing distance from the Earth and may even reverse so that at distances X less than approx. 10 to -12 R(sub E), depending on magnetic activity, the dawn sector has slightly higher pressure. The temperature and density asymmetries in the near-Earth region are consistent with the ion westward gradient/curvature drift as the ions ExB convect earthward. When the solar wind dynamic pressure increases, CPS density and pressure appear to increase, but the temperature remains relatively constant. Comparison with previously published work indicates good agreement between the inferred pressure, temperature, and density and those obtained from in situ data. This new method should provide a continuous mechanism to monitor the pressure, temperature, and density in the magnetotail with unprecedented comprehensiveness.
Wing, Simon↗
On the steady flow of gas from the nuclei of Seyfert galaxies
Heating of gas energy released during explosive events produces hot winds in Seyfert nuclei. Steady-state solutions indicate that supersonic velocities up to about 800 km per sec are obtainable. Lyman continuum radiation emitted by the wind ionizes and maintains temperature of cooler gas clouds seen in emission, and dominates energy losses during early stages of expansion. A study of stability of the thermal equilibrium state leads to a two-component model: a hot stable phase (the wind), in pressure equilibrium with a cooler stable phase (clouds). Extreme variations in cloud electron densities are a consequence of the steep decrease with radius of external pressure. Cloud dynamics are related to the radius of formation and internal parameters. Permitted lines of H are emitted by high-density clouds formed at the base of the wind, while forbidden lines arise in radially moving clouds, produced throughout the wind.
Wolfe, A. M.↗
Inflatable traversing probe seal
An inflatable seal acts as a pressure-tight zipper to provide traversing capability for instrumentation rakes and probes. A specially designed probe segment with a teardrop cross-section in the vicinity of the inflatable seal minimizes leakage at the interface. The probe is able to travel through a lengthwise slot in a pressure vessel or wind tunnel section, while still maintaining pressure integrity. The design uses two commercially available inflatable seals, opposing each other, to cover the probe slot in a wind tunnel wall. Proof-of-concept tests were conducted at vessel pressures up to 30 psig, with seals inflated to 50 psig, showing no measurable leakage along the seal's length or around the probe teardrop cross-section. This seal concept can replace the existing technology of sliding face plate/O-ring systems in applications where lengthwise space is limited.
Trimarchi, Paul A.↗
Postrefurbishment mission Hubble Space Telescope images of the core of the Orion Nebula: Proplyds, Herbig-Haro objects, and measurements of a circumstellar disk
We report on observations of M42 made with the Hubble Space Telescope (HST) immediately after the successful repair and refurbishment mission. Images were made in the strongest optical emission lines of H I, (N II), and (O III) and in a bandpass close to V. In a previous paper, the term proplyd was introduced to describe young stars surrounded by circumstellar material rendered visible by being in an H II region. We confirm the proplyd nature of 17 of 18 objects found earlier with the HST, incorporate 13 previously known sources into the class on the basis of their emission-line appearance, and find 26 additional members not seen previously in other wavelengths. Half of the 110 stars brighter than V = 21 show proplyd structure, which implies that more than half of the stars have circumstellar material since nebular structures are more difficult to detect than stars. The highly variable forms of the proplyds can be explained on the basis of balance of ambient stellar gas pressure and radial pressure arising from the stellar wind and radiation pressure of the dominant stars in the region. Arguments are presented explaining the proplyds as disks or flattened envelopes surrounding young stars, hence they are possible planetary disks. The characteristic mass of ionized material is 2 x 10(exp 28) g, which becomes a lower limit to the total mass of the proplyds. A new, coordinate-based, designation scheme for compact sources and stars in the vicinity of M42 is proposed and applied. Evidence is presented that one of the previously known bright Herbig-Haro objects (HH 203) may be the result of a stream of material coming from a proplyd shocking against the neutral lid that covers M42. One object, 183-405, is a proplyd seen only in silhouette against the bright nebular background. It is elliptical, with dimensions 0.9 sec by 1.2 sec and surrounds a pre-main-sequence star of at least 0.2 solar mass. The outer parts of this stellar disk are optically thin and allow column mass densities to be determined. We set a lower limit to this disk to be 0.1-4.4 x 10(exp 28) g, dependent on the assumed gas to dust mass ratio.
O'Dell, C. R.↗
User Guide for TROPICS Data Products
This document provides information for using the data products available from the “Time-Resolved Observations of Precipitation structure and storm Intensity with a Constellation of Smallsats” (TROPICS) mission. The TROPICS mission will produce a range of data products that will be available at the NASA Goddard Earth Sciences Data and Information Services Center (GES DISC). The data products will be produced at the TROPICS Data Processing Center (UW-M SSEC), and consist of Level-1 radiances (antenna and brightness temperatures), Level-2a unified resolution radiance, Level-2b Atmospheric Vertical Temperature Profiles (AVTP), Level-2b Atmospheric Vertical Moisture Profiles (AVMP), Level-2b Instantaneous Surface Rain Rate (ISRR), and Level-2b Tropical Cyclone (TC) intensity algorithms to estimate two primary variables: Minimum Sea Level Pressure (MSLP) and Maximum Sustained Winds (MSW). Two independent intensity estimation methods are included: 1) the Tropical Cyclone Intensity Estimate algorithm (TCIE) developed at the University of Wisconsin/CIMSS using native microwave brightness temperatures and 2) the Hurricane Intensity and Structure Algorithm (HISA) developed at Colorado State University/CIRA using microwave retrievals of temperature, moisture, and integrated quantities. In addition to MSW and MSLP, HISA also provides estimates of surface wind radii and 2D winds at standard pressure levels. TROPICS is adapting the NOAA STAR Microwave Integrated Retrieval System (MIRS) to retrieve the AVTP and AVMP data products. The ISRR algorithm uses the NASA Goddard Precipitation Retrieval and Profiling Scheme (PRPS).
TROPICS↗
Implementation of a Pulsed-Laser Measurement System in the National Transonic Facility
A remotely-adjustable laser transmission and imaging system has been developed for use in a high-pressure, cryogenic wind tunnel. Implementation in the National Transonic Facility has proven the system suitable for velocity and signal lifetime measurements over a range of operating conditions. The measurement system allows for the delivery of high-powered laser pulses through the outer pressure shell and into the test section interior from a mezzanine where the laser is free from environmental disturbances (such as vibrations and excessive condensation) associated with operation of the wind tunnel. Femtosecond laser electronic excitation tagging (FLEET) was utilized to provide freestream velocity measurements, and first results show typical data that may be obtained using the system herein described.
Reese, Daniel T.↗
Low-Pressure Capability of NASA Glenn's 10- by 10-Foot Supersonic Wind Tunnel Expanded
Extremely low dynamic pressure Q conditions are desired for space-related research including the testing of parachute designs and other decelerator concepts for future vehicles landing on Mars. Therefore, the low-pressure operating capability of the Abe Silverstein 10- by 10-foot Supersonic Wind Tunnel (10 10 SWT) at NASA Glenn Research Center was recently increased. Successful checkout tests performed in the fall of 2002 showed significantly reduced minimum operating pressures in the wind tunnel.
Roeder, James W.↗
Preliminary results of buffet tests in a cryogenic wind tunnel
Buffet tests of two wings with different leading-edge sweep show that it is feasible to use the standards wing root bending moment technique in a cryogenic wing tunnel. The results for the 65 deg sweep delta wing indicate the importance of matching the reduced frequency parameter in model tests for planforms which are sensitive to reduced frequency parameter if quantitative buffet measurements are required. The unique ability of a pressurized cryogenic wind tunnel to separate the effects of Reynolds number and of aeroelastic distortion by variations in the tunnel stagnation temperature and pressure was demonstrated.
Boyden, R. P.↗
Anatomy of Continuous Mars SEIS and Pressure Data from Unsupervised Learning
The seismic noise recorded by the Interior Exploration using Seismic Investigations, Geodesy, and Heat Transport (InSight) seismometer (Seismic Experiment for Interior Structure [SEIS]) has a strong daily quasi-periodicity and numerous transient microevents, associated mostly with an active Martian environment with wind bursts, pressure drops, in addition to thermally induced lander and instrument cracks. That noise is far from the Earth’s microseismic noise. Quantifying the importance of nonstochasticity and identifying these microevents is mandatory for improving continuous data quality and noise analysis techniques, including autocorrelation. Cataloging these events has so far been made with specific algorithms and operator’s visual inspection. We investigate here the continuous data with an unsupervised deep-learning approach built on a deep scattering network. This leads to the successful detection and clustering of these microevents as well as better determination of daily cycles associated with changes in the intensity and color of the background noise. We first provide a description of our approach, and then present the learned clusters followed by a study of their origin and associated physical phenomena. We show that the clustering is robust over several Martian days, showing distinct types of glitches that repeat at a rate of several tens per sol with stable time differences. We show that the clustering and detection efficiency for pressure drops and glitches is comparable to or better than manual or targeted detection techniques proposed to date, noticeably with an unsupervised approach. Finally, here we discuss the origin of other clusters found, especially glitch sequences with stable time offsets that might generate artifacts in autocorrelation analyses. We conclude with presenting the potential of unsupervised learning for long-term space mission operations, in particular, for geophysical and environmental observatories.
58 GEOSCIENCES↗
Skylab 2 ground winds data reduction and statistical analysis
A ground winds test was conducted on the Skylab 2 spacecraft in a subsonic wind tunnel and the results were tape recorded for analysis. The data reduction system used to analyze the tapes for full scale, first and second mode bending moments, or acceleration plots versus dynamic pressure or wind velocity is explained. Portions of the Skylab 2 tape data were analyzed statistically in the form of power spectral densities, autocorrelations, and cross correlations to introduce a concept of using system response decay as a measure of linear system damping.
Source record↗