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NASA NTRSDate not supplied

Space Launch System Base Aerodynamics Post-Flight Reconstruction for Artemis I

Artemis I was the first uncrewed integrated test flight of the NASA heavy-lift, human-rated, exploration-class launch vehicle, Space Launch System (SLS), and Orion spacecraft. Artemis I successfully launched from Pad39B at NASA Kennedy Space Center on November 16th, 2022. The integrated test flight was composed of launch and ascent of SLS vehicle from lift-off to RS-25 main engine cut-off (MECO), interim cryogenic propulsion stage (ICPS) in-space flight and Orion’s trajectory around the moon and landing in the Pacific Ocean which occurred on December 11th, 2022. The SLS total thrust of 8,800,000 lbf was powered by four LOX/LH2 RS-25 engines and two 5-segment solid rocket boosters. As a result, the base flow field had highly complex phenomena and regimes. SLS base aerodynamics covers vehicle base pressure and integrated axial force during powered flight from lift-off to MECO. This work discusses the SLS base flow physics observed during Artemis I and comparisons of post-flight reconstruction with pre-flight models and Space Shuttle data. This was the first time in-depth base aerodynamics flight reconstruction has been investigated for an exploration-class launch vehicle since the Saturn V Program.

aerothermodynamics↗

NASA NTRSDate not supplied

Base Aerodynamics Post-Flight Reconstruction for Artemis I

aerothermodynamics↗

DOE OSTI2022

Performance and Cost Potential for Exemplar Direct Supercritical Carbon Dioxide Natural Gas Plants

This report presents the techno-economic analysis (TEA) optimization results of natural gas-fired utility-scale power plants based on the direct supercritical carbon dioxide (sCO 2 ) power cycle. To identify optimum plant configuration, the study also considered three different cases (Case A, Case B, Case C) with varying levels of thermal integration with the plant air separation unit (ASU). A fourth case (Case D), which is based on a patent from 8 Rivers, was also considered and includes thermal integration with the ASU as well as compressed recycle carbon dioxide (CO 2 ) gas. The four direct sCO 2 power plants offered similar or slightly higher plant efficiencies than the reference NGCC plants based on an F-class gas turbine with carbon capture and storage (CCS). LCOE of the direct sCO 2 plants is 13.5–17.2 percent higher than the reference NGCC plants with CCS due to higher capital costs associated with the ASU and sCO 2 power block. Recuperators make up over 50 percent of the power cycle costs. Consequently, any research and development (R&D) efforts to reduce the recuperator capital costs will be beneficial for the technology commercialization. The study also investigated the impact of co-firing landfill gas (LFG) and natural gas on plant efficiency, LCOE, and CO 2 emissions. Increasing the LFG co-firing from 0 percent to 50 percent (mass basis), decreased the plant efficiency by 0.3 percentage points and increased the LCOE by 3 percent. Due to high inherent CO 2 capture rates, direct sCO 2 plants have strong potential to achieve net-zero CO 2 emissions with LFG and natural gas co-firing.

03 NATURAL GAS↗

NASA NTRS1994

Near-infrared imaging of Markarian 231: Evidence for a double nucleus

Near-infrared (1.2-2.4 micrometers) images are presented for the central 10 arcsec of the Seyfert 1 galaxy Markarian 231. We find a faint, but intrinsically luminous (M(sub k) approximately -20.7) secondary peak in the near-infrared light distribution approximately 3.5 arcsec (2.7 kpc) south of the primary Seyfert 1 nucleus. Since there is no optical or infrared evidence for ongoing star formation at the location of this secondary peak, and its near-infrared luminosity and color are comparable to slightly reddened spiral bulges or elliptical nuclei, we identify this peak with the stripped nucleus of the companion galaxy involved in the Mrk 231 merger event. Depending upon the exact ratio of the masses of the primary and secondary nucleus in the Mrk 231 system we estimate a merger time scale of less than or equal to 10(exp 9) yr. The morphology of the southern nucleus suggests that it may have recently survived a close passage (r less than 200 pc) with the Seyfert 1 nucleus on a highly elliptical orbit, in which case the merger time scale may be significantly shorter (approximately 10(exp 7) yr. We re-calculate the average merger time scale for the seven ultraluminous infrared galaxies with double nuclei in the Bright Galaxy Sample (the BGS) of Soifer et al. (AJ, 98, 766 (1989)) and derive a value of approximately 10(exp 8) yr. Since seven of ten of the ultraluminous infrared galaxies in the BGS are now known to be double, we estimate the ultraluminous 'phase' may be close to this value. Along with Arp 220 and Mrk 273, Mrk 231 is the third member of the class to possess a high brightness temperature non-thermal radio core and a double nucleus, suggesting the time scale for the generation or fueling of the active nucleus can be much less than the dynamical time scale for the merger of the progenitor nuclei.

Armus, L.↗

NASA NTRS1995

Predictions of adult Anopheles albimanus densities in villages based on distances to remotely sensed larval habitats

Remote sensing is particularly helpful for assessing the location and extent of vegetation formations, such as herbaceous wetlands, that are difficult to examine on the ground. Marshes that are sparsely populated with emergent macrophytes and dense cyanobacterial mats have previously been identified as very productive Anopheles albimanus larval habitats. This type of habitat was detectable on a classified multispectral System Probatoire d'Observation de la Terre image of northern Belize as a mixture of two isoclasses. A similar spectral signature is characteristic for vegetation of river margins consisting of aquatic grasses and water hyacinth, which constitutes another productive larval habitat. Based on the distance between human settlements (sites) of various sizes and the nearest marsh/river exhibiting this particular class combination, we selected two groups of sites: those located closer than 500 m and those located more than 1,500 m from such habitats. Based on previous adult collections near larval habitats, we defined a landing rate of 0.5 mosquitoes/human/min from 6:30 PM to 8:00 PM as the threshold for high (> or = 0.5 mosquitoes/human/min) versus low (< 0.5 mosquitoes/human/min) densities of An. albimanus. Sites located less than 500 m from the habitat were predicted as having values higher than this threshold, while lower values were predicted for sites located greater than 1,500 m from the habitat. Predictions were verified by collections of mosquitoes landing on humans. The predictions were 100% accurate for sites in the > 1,500-m category and 89% accurate for sites in the < 500-m category.

NASA Discipline General Space Life Sciences↗

NASA NTRS2005

X-rays from Cepheus A East and West

We report the discovery of X-rays from both components of Cepheus A, East and West, with the XMM-Newton observatory. HH 168 joins the ranks of other energetic Herbig-Haro objects that are sources of T &GE; 10(6) K X-ray emission. The effective temperature of HH 168 is T = 5.8(-2.3)(+3.5) x 10(6) K, and its unabsorbed luminosity is 1: 1; 10(29) ergs s(-1), making it hotter and less luminous than other representatives of its class. We also detect prominent X-ray emission from the complex of compact radio sources believed to be the power sources for Cep A. We call this source HWX, and it is distinguished by its hard X-ray spectrum, T = 1.2(-0.5)(+1.2) 10(8) K, and its complex spatial distribution. It may arise from one or more protostars associated with the radio complex, the outflows, or a combination of the two. We detect 102 X-ray sources, many presumed to be pre-main-sequence stars on the basis of the reddening of their optical and IR counterparts.

Herbig-Haro objects↗

NASA NTRS1980

Magnetic field orientation and suprathermal ion streams in the earth's foreshock

It is noted that as a result of the ISEE 1 and 2 missions, it was found that return ions, that is, ions streaming into the solar wind away from the bow shock, are comprised of separate classes having distinguishable energy and directional distributions. In addition, each of these classes of return ions, which are essentially all protons, is associated with its own level of upstream magnetic wave activity. It is shown that each class is also associated with a particular section of the foreshock determined by the IMF and the energies of the particles themselves. A series of schematic figures depicting the IMF-shock geometry for selected instants during the first two hours of ISEE particle data of November 8, 1977, is presented.

Greenstadt, E. W.↗

NASA NTRS1993

NASA Langley Research Center's distributed mass storage system

There is a trend in institutions with high performance computing and data management requirements to explore mass storage systems with peripherals directly attached to a high speed network. The Distributed Mass Storage System (DMSS) Project at NASA LaRC is building such a system and expects to put it into production use by the end of 1993. This paper presents the design of the DMSS, some experiences in its development and use, and a performance analysis of its capabilities. The special features of this system are: (1) workstation class file servers running UniTree software; (2) third party I/O; (3) HIPPI network; (4) HIPPI/IPI3 disk array systems; (5) Storage Technology Corporation (STK) ACS 4400 automatic cartridge system; (6) CRAY Research Incorporated (CRI) CRAY Y-MP and CRAY-2 clients; (7) file server redundancy provision; and (8) a transition mechanism from the existent mass storage system to the DMSS.

Pao, Juliet Z.↗

NASA NTRSDate not supplied

Space Launch System Base Aerothermodynamics Post-Flight Reconstruction for Artemis I

Artemis I was the first uncrewed integrated test flight of the NASA heavy-lift, human-rated, exploration-class launch vehicle, Space Launch System (SLS), and Orion spacecraft. Artemis I successfully launched from Pad39B at NASA Kennedy Space Center on November 16th, 2023. The integrated test flight is composed of launch and ascent of the SLS vehicle from lift-off to RS-25 main engine cut-off (MECO), interim cryogenic propulsion stage (ICPS) in-space flight and Orion’s trajectory around the moon and landing in the Pacific Ocean which occurred on December 11th, 2023. The SLS total thrust of 8,800,000 lbf is powered by four LOX/LH2 RS-25 engines and two 5-segment solid rocket boosters. As a result, base flow environments for this vehicle are highly complex and extreme. SLS base aerothermodynamics covers rocket plume-induced convection and radiation of the vehicle’s aft region during powered flight from lift-off to MECO. This work discusses the SLS base flow physics observed during Artemis I and comparisons of post-flight reconstruction with pre-flight models and Space Shuttle data. This is the first time in-depth base heating flight reconstruction has been investigated for an exploration-class launch vehicle since the Saturn V Program.

aerothermodynamics↗

NASA NTRSDate not supplied

Space Launch System Base Aerothermodynamics Post-Flight Reconstruction for Artemis I

Artemis I was the first uncrewed integrated test flight of the NASA heavy-lift, human-rated, exploration-class launch vehicle, Space Launch System (SLS), and Orion spacecraft. Artemis I successfully launched from Pad39B at NASA Kennedy Space Center on November 16th, 2023. The integrated test flight is composed of launch and ascent of the SLS vehicle from lift-off to RS-25 main engine cut-off (MECO), interim cryogenic propulsion stage (ICPS) in-space flight and Orion’s trajectory around the moon and landing in the Pacific Ocean which occurred on December 11th, 2023. The SLS total thrust of 8,800,000 lbf is powered by four LOX/LH2 RS-25 engines and two 5-segment solid rocket boosters. As a result, base flow environments for this vehicle are highly complex and extreme. SLS base aerothermodynamics covers rocket plume-induced convection and radiation of the vehicle’s aft region during powered flight from lift-off to MECO. This work discusses the SLS base flow physics observed during Artemis I and comparisons of post-flight reconstruction with pre-flight models and Space Shuttle data. This is the first time in-depth base heating flight reconstruction has been investigated for an exploration-class launch vehicle since the Saturn V Program.

aerothermodynamics↗

NASA NTRS1985

Optimum search strategy for randomly distributed CW transmitters

The relative probability of detecting randomly distributed CW transmitters as a function of the fraction of the sky which is searched (in a fixed time interval) is given. It is shown that the probability of detecting such a class of transmitters with a given receiving system is a maximum if the entire sky is searched, provided that the receiving system is sufficiently sensitive to detect the nearest transmitter in the allocated time and that the integration time - bandwidth product in a specified direction is greater than 8.

Gulkis, S.↗

NASA NTRS2016

Tropical Cyclone Activity in the North Atlantic Basin During the Weather Satellite Era, 1960-2014

This Technical Publication (TP) represents an extension of previous work concerning the tropical cyclone activity in the North Atlantic basin during the weather satellite era, 1960-2014, in particular, that of an article published in The Journal of the Alabama Academy of Science. With the launch of the TIROS-1 polar-orbiting satellite in April 1960, a new era of global weather observation and monitoring began. Prior to this, the conditions of the North Atlantic basin were determined only from ship reports, island reports, and long-range aircraft reconnaissance. Consequently, storms that formed far from land, away from shipping lanes, and beyond the reach of aircraft possibly could be missed altogether, thereby leading to an underestimate of the true number of tropical cyclones forming in the basin. Additionally, new analysis techniques have come into use which sometimes has led to the inclusion of one or more storms at the end of a nominal hurricane season that otherwise would not have been included. In this TP, examined are the yearly (or seasonal) and 10-year moving average (10-year moving average) values of the (1) first storm day (FSD), last storm day (LSD), and length of season (LOS); (2) frequencies of tropical cyclones (by class); (3) average peak 1-minute sustained wind speed ( ) and average lowest pressure ( ); (4) average genesis location in terms of north latitudinal ( ) and west longitudinal ( ) positions; (5) sum and average power dissipation index ( ); (6) sum and average accumulated cyclone energy ( ); (7) sum and average number of storm days ( ); (8) sum of the number of hurricane days (NHD) and number of major hurricane days (NMHD); (9) net tropical cyclone activity index (NTCA); (10) largest individual storm (LIS) PWS, LP, PDI, ACE, NSD, NHD, NMHD; and (11) number of category 4 and 5 hurricanes (N4/5). Also examined are the December-May (D-M) and June-November (J-N) averages and 10-year moving average values of several climatic factors, including the (1) oceanic Nino index ( ); (2) Atlantic multi-decadal oscillation ( ) index; (3) Atlantic meridional mode ( ) index; (4) global land-ocean temperature index ( ); and (5) quasi-biennial oscillation ( ) index. Lastly, the associational aspects (using both linear and nonparametric statistical tests) between selected tropical cyclone parameters and the climatic factors are examined based on their 10-year moving average trend values.

satellite↗

NASA NTRS1984

Spatial distribution of craters on the Moon and Callisto

The spatial distribution of craters 8 km diameter on an area of Callisto are compared with that of a lunar highlands area from which craters are removed to produce the Callisto size/frequency distribution. Craters in the lunar area are mapped and classified according to degradational type using the five-fold LPL scheme where Class 1 is the freshest and Class 5 the most degraded. The size/frequency distribution are determined and compared with the Callisto area. Craters are removed according to the stage of degradation. Its crater population is basically a production population deficient in large craters relative to that of the terrestrial planets. This indicates that the population of impacting objects responsible for the period of heavy bombardment in the inner solar system was different from that at Jupiter, and probably had a different origin as well.

Ruzicka, A.↗

NASA NTRS2009

Metal Decorated Multi-Walled Carbon Nanotube/Polyimide Composites with High Dielectric Constants and Low Loss Factors

The measurement of observable electromagnetic phenomena in materials and their derived intrinsic electrical material properties are of prime importance in the discovery and development of material systems for electronic and aerospace applications. Nanocomposite materials comprised of metal decorated multi-walled carbon nanotubes (MWCNTs) were prepared by a facile method and characterized. Metal particles such as silver(Ag), platinum(Pt) and palladium(Pd) with diameters ranging from less than 5 to over 50 nanometers were distributed randomly on the MWCNTs. The present study is focused on silver decorated MWCNTs dispersed in a polyimide matrix. The Ag-containing MWCNTs were melt mixed into Ultem(TradeMark) and the mixture extruded as ribbons. The extruded ribbons exhibited a moderate to high degree of MWCNT alignment as determined by HRSEM. These ribbons were then fabricated into test specimens while maintaining MWCNT alignment and subsequently characterized for electrical and electromagnetic properties at 8-12 GHz. The results of the electromagnetic characterization showed that certain sample configurations exhibited a decoupling of the permittivity (epsilon ) and loss factor (epsilon") indicating that these properties could be tailored within certain limits. The decoupling and independent control of these fundamental electrical material parameters offers a new class of materials with potential applications in electronics, microwave engineering and optics.

Elliott, Holly A.↗

NASA NTRS2012

X-Ray Emission from Supernovae in Dense Circumstellar Matter Environments: A Search for Collisionless Shock

The optical light curve of some supernovae (SNe) may be powered by the outward diffusion of the energy deposited by the explosion shock (so-called shock breakout) in optically thick (tau approx > 30) circumstellar matter (CSM). Recently, it was shown that the radiation-mediated and -dominated shock in an optically thick wind must transform into 8. collisionless shock and can produce hard X-rays. The X-rays are expected to peak at late times, relative to maximum visible light. Here we report on a search, using Swift-XRT and Chandra, for X-ray emission from 28 SNe that belong to classes whose progenitors are suspected to be embedded in dense CSM. Our sample includes 19 type-IIn SNe, one type-Ibn SN and ei~ht hydrogen-poor super-luminous SNe (SLSN-I; SN 2005ap like). Two SNe (SN 2006jc and SN 2010jl) have X-ray properties that are roughly consistent with the expectation for X-rays from a collisionless shock in optically thick CSl\l. Therefore, we suggest that their optical light curves are powered by shock breakout in CSM. We show that two other events (SN 2010al and SN 2011ht) were too X-ray bright during the SN maximum optical light to be explained by the shock breakout model. We conclude that the light curves of some, but not all, type-IIn/Ibn SNe are powered by shock breakout in CSM. For the rest of the SNe in our sample, including all the SLSN-I events, our X-ray limits are not deep enough and were typically obtained at too early times (i.e., near the SN maximum light) to conclude about their nature. Late time X-ray observations are required in order to further test if these SNe are indeed embedded in dense CSM. We review the conditions required for a shock breakOut in a wind profile. We argue that the time scale, relative to maximum light, for the SN to peak in X-rays is a probe of the column density and the density profile above the shock region. The optical light curves of SNe, for which the X-ray emission peaks at late times, are likely powered by the diffusion of shock energy from a dense CSM. We note that if the CSM density profile falls faster than a constant-rate wind density profile, then X-rays may escape at earlier times than estimated for the wind profile case. Furthermore, if the CSM have a region in which the density profile is very steep, relative to a steady wind density profile, or the CSM is neutral, then the radio free-free absorption may be low enough, and radio emission may be detected.

Ofek, E.O↗

NASA NTRS2023

Revisiting Empirical Solar Energetic Particle Scaling Relations. I. Solar Flares

Aims. The possible influence of solar superflares on the near-Earth space radiation environment are assessed through the investigation of scaling laws between the peak proton flux and fluence of solar energetic particle (SEP) events with the solar flare soft X-ray peak photon flux. Methods. We compiled a catalog of 65 well-connected (W20-90) SEP events during the last three solar cycles covering a period of ∼34 yr (1984–2020) that were associated with flares of class ≥C6.0, and investigated the statistical relations between the recorded peak proton fluxes (I p ) and the fluences (F p ) at a set of integral energies from E > 10, > 30, and > 60 to > 100 MeV versus the associated solar flare peak soft X-ray flux in the 1–8 Å band (F SXR ). Based on the inferred relations, we calculated the integrated energy dependence of the peak proton flux (I p ) and fluence (F p ) of the SEP events, assuming that they follow an inverse power law with respect to energy. Finally, we made use of simple physical assumptions, combining our derived scaling laws, and estimated the upper limits for I p and F p focusing on the flare associated with the strongest ground level enhancement (GLE) directly observed to date (GLE 05 on 23 February 1956), and that inferred for the cosmogenic radionuclide-based SEP event of AD774/775. Results. A scaling law relating I p and F p to the solar soft X-ray peak intensity (F SXR ) as ∝ F 5/6 SXR for a flare with a F SXR = X600 (in the revised scale) is consistent with values of FP inferred for the cosmogenic nuclide event of AD774/775.

Athanasios Papaioannou↗

NASA NTRS1987

The spatial distribution of dwarf galaxies in the CfA slice of the universe

A complete (with the the exception of one) redshift sample of 58 galaxies in the Nilson catalog classified as dwarf, irregular, or Magellanic irregular is used to investigate the large-scale clustering properties of these low-surface brightness galaxies in the CfA slice of the universe (alpha in the range of 8-17 h, delta in the range of 26.5-32.5 deg). It is found that the low-surface brightness dwarf galaxies also lie on the structures delineated by the high-surface brightness normal galaxies and that they do not fill in the voids. This is inconsistent with a class of biased galaxy formation theories which predict that dwarf galaxies should be present everywhere, including the voids.

Thuan, Trinh X.↗

NASA NTRS1988

Calculation of space station infrared irradiance from atmosphere-induced emissions

The excitation mechanisms and radiance estimates over the 1 to 10 micron region for CO2(v), H2O(v), CO(v), OH(v), NO2(2B-2A) and N2(B3 pi - A3 sigma) are discussed. The infrared irradiance of the Space Station at an altitude of 460 km was estimated. The surface material was presumed to be non-carbonaceous and inert. The determined number densities of the various gases relevant to the Space Station from both ambient and outgassing sources are presented. A model for the production of and emission from the infrared active molecules was constructed that considers two classes of production processes: (1) gas phase excitation of molecules in the near Station environment by collision with ambient flux; and (2) surface processes that lead to molecular excitation. A composite spectrum of all major emitting species shows that the observed irradiance is non-uniform over the 1 to 8 micron region. The comparison of predicted irradiance with the zodiacal background indicates that the Space Station infrared background from atmosphere-induced emissions may be a problem of consequence.

Fraser, M. E.↗