Search NASA⌕ Search

SEARCH · Search NASA

Results for “Far East”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Simulation of sugar kelp ( Saccharina latissima ) breeding guided by practices to accelerate genetic gains

Abstract Though Saccharina japonica cultivation has been established for many decades in East Asian countries, the domestication process of sugar kelp (Saccharina latissima) in the Northeast United States is still at its infancy. In this study, by using data from our breeding experience, we will demonstrate how obstacles for accelerated genetic gain can be assessed using simulation approaches that inform resource allocation decisions. Thus far, we have used 140 wild sporophytes that were sampled in 2018 from the northern Gulf of Maine to southern New England. From these sporophytes, we sampled gametophytes and made and evaluated over 600 progeny sporophytes from crosses among the gametophytes in 2019 and 2020. The biphasic life cycle of kelp gives a great advantage in selective breeding as we can potentially select both on the sporophytes and gametophytes. However, several obstacles exist, such as the amount of time it takes to complete a breeding cycle, the number of gametophytes that can be maintained in the laboratory, and whether positive selection can be conducted on farm-tested sporophytes. Using the Gulf of Maine population characteristics for heritability and effective population size, we simulated a founder population of 1,000 individuals and evaluated the impact of overcoming these obstacles on rate of genetic gain. Our results showed that key factors to improve current genetic gain rely mainly on our ability to induce reproduction of the best farm-tested sporophytes, and to accelerate the clonal vegetative growth of released gametophytes so that enough gametophyte biomass is ready for making crosses by the next growing season. Overcoming these challenges could improve rates of genetic gain more than 2-fold. Future research should focus on conditions favorable for inducing spring reproduction, and on increasing the amount of gametophyte tissue available in time to make fall crosses in the same year.

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRS2016

Oceanic Transport of Surface Meltwater from the Southern Greenland Ice Sheet

The Greenland ice sheet has undergone accelerating mass losses during recent decades. Freshwater runoff from ice melt can influence fjord circulation and dynamic1 and the delivery of bioavailable micronutrients to the ocean. It can also have climate implications, because stratification in the adjacent Labrador Sea may influence deep convection and the strength of the Atlantic meridional overturning circulation. Yet, the fate of the meltwater in the ocean remains unclear. Here, we use a high-resolution ocean model to show that only 1-15% of the surface meltwater runoff originating from southwest Greenland is transported westwards. In contrast, up to 50-60% of the meltwater runoff originating from southeast Greenland is transported westwards into the northern Labrador Sea, leading to significant salinity and stratification anomalies far from the coast. Doubling meltwater runoff, as predicted in future climate scenarios, results in a more-than-double increase in anomalies offshore that persists further into the winter. Interannual variability in offshore export of meltwater is tightly related to variability in wind forcing. The new insight that meltwaters originating from the west and east coasts have different fates indicates that future changes in mass loss rates and surface runoff will probably impact the ocean differently, depending on their Greenland origins.

Physical oceanography↗
NASA NTRS2000

Monsoon-Enso Relationships: A New Paradigm

This article is partly a review and partly a new research paper on monsoon-ENSO relationship. The paper begins with a discussion of the basic relationship between the Indian monsoon and ENSO dating back to the work of Sir Gilbert Walker up to research results in more recent years. Various factors that may affect the monsoon-ENSO, relationship, including regional coupled ocean-atmosphere processes, Eurasian snow cover, land-atmosphere hydrologic feedback, intraseasonal oscillation, biennial variability and inter-decadal variations, are discussed. The extreme complex and highly nonlinear nature of the monsoon-ENSO relationship is stressed. We find that for regional impacts on the monsoon, El Nino and La Nina are far from simply mirror images of each other. These two polarities of ENSO can have strong or no impacts on monsoon anomalies depending on the strength of the intraseasonal oscillations and the phases of the inter-decadal variations. For the Asian-Australian monsoon (AAM) as a whole, the ENSO impact is effected through a east-west shift in the Walker Circulation. For rainfall anomalies over specific monsoon areas, regional processes play important roles in addition to the shift in the Walker Circulation. One of the key regional processes identified for the boreal summer monsoon is the anomalous West Pacific Anticyclone (WPA). This regional feature has similar signatures in interannual and intraseasonal time scales and appears to determine whether the monsoon-ENSO relationship is strong or weak in a given year. Another important regional feature includes a rainfall and SST dipole across the Indian Ocean, which may have strong impact on the austral summer monsoon. Results are shown indicating that monsoon surface wind forcings may induce a strong biennial signal in ENSO and that strong monsoon-ENSO coupling may translate into pronounced biennial variability in ENSO. Finally, a new paradigm is proposed for the study of monsoon variability. This paradigm provides a unified framework in which monsoon predictability, the role of regional vs. basin-scale processes, its relationship with different climate subsystems, and causes of secular changes in monsoon-ENSO relationship can be investigated.

Lau, K. M.↗
NASA NTRS2000

Teleconnection Linking Asian/Pacific Monsoon Variability and Summertime Droughts and Floods Over the United States

Major droughts and floods over the U.S. continent may be related to a far field energy source in the Asian Pacific. This is illustrated by two climate patterns associated with summertime rainfall over the U.S. and large-scale circulation on interannual timescale. The first shows an opposite variation between the drought/flood over the Midwest and that over eastern and southeastern U.S., coupled to a coherent wave pattern spanning the entire East Asia-North Pacific-North America region related to the East Asian jetstream. The second shows a continental-scale drought/flood in the central U.S., coupled to a wavetrain linking Asian/Pacific monsoon region to North America.

Lau, K. M.↗
NASA NTRS1981

Petrochemical constraints on lateral transport during lunar basin formation

Lunar ANT petrochemistry correlates with longitude, allowing the sampled region of the moon to be divided into three geochemical provinces: western (Apollo 12 and 14), near-eastern (Apollo 11, 15, 16 and 17) and far-eastern (Luna 16, 20 and 24). A western ANT rock has a far greater Eu anomaly for a given Sm content than does a near-eastern ANT rock, which is in turn has a somewhat greater Eu anomaly than does a far-eastern ANT rock. Distinct differences are also observed in Sc/Sm and Ti/Sm ratios (western ANT rocks have lower ratios) and in the abundances of alkali-rich anorthosites (five of the six known anorthosites from the west are approximately four times richer in Na and K than are ferroan anorthosites, whereas none of the 40 known anorthosites from the near east is alkali-rich). The existence of this distinct correlation of ANT geochemical properties with longitude implies that even during the first few hundred m.y. of lunar history basin-forming impacts were not capable of efficiently redistributing material laterally across the lunar surface.

Warren, P. H.↗
DOE OSTI2025

Combining biotechnology with sustainability: feasibility of bioenergy sorghum in generating high-value bioproducts

Biofuels generated through fermentation of plant-derived lignocellulosic biomass are currently not competitive with fossil fuels. Here, a framework is described for the engineering of valuable coproducts to improve the economic feasibility of biofuel production. To accomplish this goal, the desirable traits of the bioenergy crop Sorghum bicolor are harnessed via modern engineering approaches. A robust analysis is provided to highlight the scientific basis, costs, regulatory challenges, and lucrative nature of coproduct development. Sustainable biofuel production could also have far-reaching societal impacts, especially in the context of our rapidly changing global climate. This perspective suggests that the path to profitable biofuel production is attainable and encourages consideration of similar approaches by the biotechnology industry.

09 BIOMASS FUELS↗
DOE OSTI2021

Quantitative Precipitation Estimation of Extremes in CONUS With Radar Data

When constructing an accurate, continental, in-situ-based, kilometer-scale, long-term record of the precipitation field and its spatiotemporal changes remains a significant challenge. Here, we determine the extreme-value behavior of the NEXRAD Stage IV radar-based quantitative precipitation estimate. We find that the climatology of 5-year daily return values in the contiguous United States East of the Rocky Mountains shows only slight variability on spatial scales smaller than (Formula presented.) ~100 km. In light of this finding, we test whether rain-gauge-only daily precipitation data sets can produce accurate extreme-value behavior at spatial scales finer than the spacing between gauges. We find that the 5-year daily return values are accurate at locations far from rain gauges only if the interpolation between gauges is carried out appropriately for extremes. Precipitation statistics derived from in-situ rain gauge data are therefore of sufficient spatial resolution to faithfully capture daily extremes over much of the eastern United States.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1983

An ancient depleted mantle source for Archean crust in Rajasthan, India

Data from an initial set of Banded Gneiss Complex (BGC) east of the city of Udaipur are given. In this region the BGC comprises typical grey gneiss with variably abundant granitic and mafic components. Efforts to date were concentrated on the mafic components which, based on chemical data, appear to be metavolcanic. All samples examined were recrystallized under amphibolite or upper amphibolite facies conditions. Pertinent chemical data for a small number of amphibolites analyzed so far are: SiO2: 49-53%; MgO: 5.7-7.3%; K2O: 0.24-0.50%; Ni: 106-140 ppm; Zr: 37-159 ppm. From Sm/Nd data, all amphibolites show small to moderate LREE enrichments.

Macdougall, J. D.↗
NASA NTRS1965

Ground testing at MSFC

The large-scale field collection of acoustic data and their analysis are described in this review. The entire sound-field program has the purpose of solving complex problems of excessive noise propagation associated with the static test firing of large space-booster powerplants. The site of data collection has been Mississippi Test Facility (MTF), where far-field sound-propagation and correlated meteorological measurements were initiated in 1962. The statistical evaluation of sound-measurement data shows that the polar distribution of sound in the springtime (at MTF) is determined mainly by the temperature field of the atmosphere. Greater deformation of sound-intensity polar distribution occurs in the autumn as a result of the influence of the wind field. The data on sound attenuation as a function of distance from its source revealed attenuation in excess of the expected magnitude. The excess was mainly between 1 and 10 kilometers from the source, with maximum attenuation (17 to 18 decibels) near 6 kilometers. Excess sound attenuation was compared with calculated sound dispersion. For all sound frequencies in all seasons the deviation between reference and empirical attenuation values formed a bell-shaped distribution on a semilogarithmic plot. The physical causes for the sound- attenuation behavior are considered to be atmospheric diffraction and scattering effects. Statistical analysis of sod-intensity extremes indicated amplification of the sound signals by focusing which could be expected along selected azimuths. Empirical amplification values showed the maximum occurring in winter (50 decibels at 22 kilometers). For the analysis of correlation between empirical sound data and local atmospheric sound- propagation conditions, #e concept of analytical classification of sound-velocity profiles has been developed. Examination of over a quarter-million individual sound-velocity profiles indicates that 33 profile types for heights up to 3 kilometers constitute the empirical possibilities of sound-propagation conditions in southeastern United States. Since the focusing qualities of each sound- velocity profile can be determined as a class characteristic, the overall probabilities of focusing occurrence can he obtained. The severity of focusing, as based upon lateral spread of focusing areas, has been determined. The data for MTF indicate focusing is most severe in winter, with the direction toward east being most affected. Sound propagation is a fluctuating phenomenon because atmospheric conditions vary continuously. A measuring system for analyzing the nonstationary sound-propagation phenomena has been established. The analysis of the acoustic fluctuation data is sup- posed to provide "dynamic” perturbation functions of sound, which are to be superimposed on the related characteristic sound-velocity-profile type. The ultimate result of the program will be the establishment of reliable contingency tables showing the relationship between atmospheric parameters and far-field sound intensities. These data will be the basis for more accurate sound-propagation forecasting for static firing tests.

STATIC TESTING↗
NASA NTRS1992

Far-ultraviolet MAMA detector imagery and emission-line CCD imagery of NGC 6240

An image of the luminous infrared galaxy NGC 6240 at 1480 A was obtained using a multianode microchannel array (MAMA) detector with a rocket-borne telescope. At distances greater than 12 arcsec from the nucleus, the measured ultraviolet luminosity implies intensive star formation activity equal to 2-3 times that of a spiral galaxy such as M83. Optical images in the H-beta and forbidden O III 5007 A emission lines reveal a region of high excitation east of the nucleus between the centers of disks 1 and 2 as described by Bland-Hawthorn et al.

Smith, Andrew M.↗
NASA NTRS1972

Identification and interpretation of tectonic features from ERTS-1 imagery

The author has identified the following significant results. An important fault zone, which is strongly suspected of being seismically active, was identified on RBV images, ERTS E-1013-17305 (101, 201, and 301), in northeastern Utah. This fault zone is not shown on the Geological Map of the United States nor on the Tectonic Map of North America. When the epicenters of historic earthquakes and their magnitudes were plotted on an overlay corresponding to the scene, a major earthquake cluster up to magnitude 4.9 was found through which the fault zone passes. This suspected active fault zone runs in a northwest-southwest direction cutting across the Patmos Mountains and the southwestern side of the East Tavaputs Plateau from near the junction of the Colorado River with the Dolores River to and beyond the town of Dragerton, Utah. The fault zone which will subsequently be referred to as the Dragerton fault zone appears to be an element of a major tectonic lineament which includes the Moab fault, Salt Valley, Spanish and Lisbon Valleys. Because of the limited imagery coverage received so far, the extent of this lineament or its tectonic significance cannot be ascertained. It is suspected, however, that it constitutes a major crustal break in the Colorado Plateau.

Abdel-Gawad, M.↗
NASA NTRS2008

Long-term Satellite Observations of Asian Dust Storm: Source, Pathway, and Interannual Variability

Among the many components that contribute to air pollution, airborne mineral dust plays an important role due to its biogeochemical impact on the ecosystem and its radiative-forcing effect on the climate system. In East Asia, dust storms frequently accompany the cold and dry air masses that occur as part of springtime cold front systems. Outbreaks of Asian dust storms occur often in the arid and semi-arid areas of northwestern China -about 1.6x10(exp 6) square kilometers including the Gobi and Taklimakan deserts- with continuous expanding of spatial coverage. These airborne dust particles, originating in desert areas far from polluted regions, interact with anthropogenic sulfate and soot aerosols emitted from Chinese megacities during their transport over the mainland. Adding the intricate effects of clouds and marine aerosols, dust particles reaching the marine environment can have drastically different properties than those from their sources. Furthermore, these aerosols, once generated over the source regions, can be transported out of the boundary layer into the free troposphere and can travel thousands of kilometers across the Pacific into the United States and beyond. In this paper, we will demonstrate the capability of a new satellite algorithm to retrieve aerosol properties (e.g., optical thickness, single scattering albedo) over bright-reflecting surfaces such as urban areas and deserts. Such retrievals have been difficult to perform using previously available algorithms that use wavelengths from the mid-visible to the near IR because they have trouble separating the aerosol signal from the contribution due to the bright surface reflectance. This new algorithm, called Deep Blue, utilizes blue-wavelength measurements from instruments such as SeaWiFS and MODIS to infer the properties of aerosols, since the surface reflectance over land in the blue part of the spectrum is much lower than for longer wavelength channels. Reasonable agreements have been achieved between Deep Blue retrievals of aerosol optical thickness and those directly from AERONET sunphotometers over desert and semi-desert regions. New Deep Blue products will allow scientists to determine quantitatively the aerosol properties near sources using high spatial resolution measurements from SeaWiFS and MODIS-like instruments. Long-term satellite measurements (1998 - 2007) from SeaWiFS will be utilized to investigate the interannual variability of source, pathway, and dust loading associated with the Asian dust storm outbreaks. In addition, monthly averaged aerosol optical thickness during the springtime from SeaWiFS will also be compared with the MODIS Deep Blue products.

Hsu, N. Christina↗
NASA NTRS2008

Recent Progress in Characterization of Dust over Land Surfaces with Space-borne Passive Remote Sensing

Among the many components that contribute to air pollution, airborne mineral dust plays an important role due to its biogeochemical impact on the ecosystem and its radiative-forcing effect on the climate system. In East Asia, dust storms frequently accompany the cold and dry air masses that occur as part of springtime cold front systems. Outbreaks of Asian dust storms occur often in the arid and semi-arid areas of northwestern China -about 1.6x10(exp 6) square kilometers including the Gobi and Taklimakan deserts- with continuous expanding of spatial coverage. These airborne dust particles, originating in desert areas far from polluted regions, interact with anthropogenic sulfate and soot aerosols emitted from Chinese mega-cities during their transport over the mainland. Adding the intricate effects of clouds and marine aerosols, dust particles reaching the marine environment can have drastically different properties than those from their sources. Furthermore, these aerosols, once generated over the source regions, can be transported out of the boundary layer into the free troposphere and can travel thousands of kilometers across the Pacific into the United States and beyond. In this paper, we will demonstrate the capability of a new satellite algorithm to retrieve aerosol properties (e.g., optical thickness, single scattering albedo) over bright-reflecting surfaces such as urban areas and deserts. Such retrievals have been difficult to perform using previously available algorithms that use wavelengths from the mid-visible to the near IR because they have trouble separating the aerosol signal from the contribution due to the bright surface reflectance. This new algorithm, called Deep Blue, utilizes blue-wavelength measurements from instruments such as SeaWiFS and MODIS to infer the properties of aerosols, since the surface reflectance over land in the blue part of the spectrum is much lower than for longer wavelength channels. Reasonable agreements have been achieved between Deep Blue retrievals of aerosol optical thickness and those directly from AERONET sunphotometers over desert and semi-desert regions. New Deep Blue products will allow scientists to determine quantitatively the aerosol properties near sources using high spatial resolution measurements from SeaWiFS and MODIS-like instruments. Long-term satellite measurements (1998 - 2007) from SeaWiFS will be utilized to investigate the interannual variability of source, pathway, and dust loading associated with the Asian dust storm outbreaks. In addition, monthly averaged aerosol optical thickness during the springtime from SeaWiFS will also be compared with the MODIS Deep Blue products.

Hsu, N. Christina↗
DOE OSTI2021

Climate hazard indices projections based on CORDEX-CORE, CMIP5 and CMIP6 ensemble

The CORDEX-CORE initiative was developed with the aim of producing homogeneous regional climate model (RCM) projections over domains world wide. In its first phase, two RCMs were run at 0.22° resolution downscaling 3 global climate models (GCMs) from the CMIP5 program for 9 CORDEX domains and two climate scenarios, the RCP2.6 and RCP8.5. The CORDEX-CORE simulations along with the CMIP5 GCM ensemble and the most recently produced CMIP6 GCM ensemble are analyzed, with focus on several temperature, heat, wet and dry hazard indicators for present day and mid-century and far future time slices. The CORDEX-CORE ensemble shows a better performance than the driving GCMs for several hazard indices due to its higher spatial resolution. For the far future time slice the 3 ensembles project an increase in all temperature and heat indices analyzed under the RCP8.5 scenario. The largest increases are always shown by the CMIP6 ensemble, except for Tx > 35 °C, for which the CORDEX-CORE projects higher warming. Extreme wet and flood prone maxima are projected to increase by the RCM ensemble over the la Plata basin in South America, the Congo basin in Africa, east North America, north east Europe, India and Indochina, regions where a better performance is obtained, whereas the GCM ensembles show small or negligible signals. Furthermore, compound hazard hotspots based on heat, drought and wet indicators are detected in each continent worldwide in region like Central America, the Amazon, the Mediterranean, South Africa and Australia, where a linear relation is shown between the heatwave and drought change signal, and region like Arabian peninsula, the central and south east Africa region (SEAF), the north west America (NWN), south east Asia, India, China and central and northern European regions (WCE, NEU) where the same linear relation is found for extreme precipitation and HW increases. Although still limited, the CORDEX-CORE initiative was able to produce high resolution climate projections with almost global coverage and can provide an important resource for impact assessment and climate service activities.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS2008

Geology of the Lachesis Tessera Quadrangle (V-18), Venus

The Lachesis Tessera Quadrangle (V-18) lies between 25deg and 50deg north, 300deg and 330deg east. Most of the quadrangle consists of "regional plains" (1) of Sedna and Guinevere Planitiae. A first draft of the geology has been completed, and the tentative number of mapped units by terrain type is: Tesserae - 2; plains - 4; ridge belts - 1; fracture belts - 1 (plus embayed fragments of possible additional belts); coronae - 3; central volcanoes - 1; shield flows - 2; paterae - 1; impact craters - 1; undifferentiated flows - 1; bright materials - 1. By far the areally most extensive materials are regional plains. These are mapped as two units, based on radar backscatter ("radar brightness"). The brighter unit appears to be younger than the darker unit. This inference is based on the common presence within the lighter unit of circular or nearly circular inliers of material with radar backscatter characteristic of the darker unit. The circular inliers are most likely low shield volcanoes, which are commonly present on the darker unit, that were only partially covered by the brighter unit. Clear cut examples of wrinkle ridges and fractures superposed on the darker unit but truncated by the brighter unit have not been found to date. These relationships indicate that the brighter unit is superposed on the darker unit, but that the difference in age between them is very small. Because they are so widespread, the regional plains are a convenient relative age time "marker." The number of impact craters superposed on these plains is too small to measure age differences (2), and thus we cannot estimate how much time elapsed between the emplacement of the darker and brighter regional plains units. More local plains units are defined by significantly lower radar backscatter or by a texture that is mottled at scores to hundreds of kilometers scale. A plains-like unit with a homogenous, bright diffuse backscatter is present as scattered exposures in the eastern part of the quadrangle. These exposures have been mapped as "bright material," but it is not clear at present if this is a valid unit or if it is part of the brighter regional plains unit. Tessera terrain is primarily found along the western border of the quadrangle, where Lachesis Tessera refers to the southern exposures, and Zirka Tessera refers to northern exposures. A second tessera unit has been mapped with the symbol "t?." This unit appears to be deformed by the requisite 2 sets of closely spaced structures, but it is so extensively flooded by regional plains materials that the structural fabric is partially obscured. Tessera terrain is present in the adjacent V-17 quadrangle, where both Lachesis Tessera and Zirka Tessera are areally more extensive than in V-18. Ridge and fracture belts are both present, but not as extensive as is the case in, for example, the Pandrosos Dorsa (3) and Lavinia Planitia (4) quadrangles. As is commonly the case, it is difficult to determine if the materials of these belts are older or younger than regional plains. A recent study using radar properties (5) demonstrated that at least most ridge belts appear to be older than regional plains. The materials of fracture belts probably are also older than regional plains, but the fractures themselves can be both older and younger than regional plains (e.g., 3).

McGill, George E.↗
NASA NTRS2023

Lunar Solar Occultation Explorer (Lunasox)

In the present decade and beyond, now 51 years after the last Apollo landing, the NASA Artemis human exploration program will offer abundant opportunities for heliophysics investigations from, by, and of the Moon from the vantage points of the lunar orbit and the surface. The Lunar Solar Occultation Explorer (LunaSOX) concept uses the lunar limb to occult the solar disk for high-resolution coronal observations at hourly, daily, to biweekly cadences from spacecraft either in the lunar orbit or at the surface. A 0.2 m diameter solar telescope in orbit with white light and narrow-band visible filters would provide arcsecond spectroscopic imaging of the low-to-high corona (1–10 R☉) with an upper limit of 10 –12 B☉ on the local scattered light background from lunar atmospheric dust, as compared to 10 –9 B☉ for Earth ground-based solar eclipse observations looking up through the atmosphere at totality. For eclipse observations from and by the Moon, there would be no significant atmospheric disturbances that otherwise limit seeing to arcsec resolution from Earth’s surface. The present eccentric orbits of the ARTEMIS P1 and P2 spacecraft are used as models for a 1 × 10 Rm orbit of LunaSOX to compute the times of solar eclipse intervals, up to 2 hours in duration between the east and west solar hemispheres at a daily cadence for coronal observations at 1–16 R☉ when the orbital aposelene is in anti-sunward directions. In a low-altitude circular orbit and from the surface, the observational cadences would, respectively, be hourly and biweekly. LunaSOX satellites also carrying in situ space environment instruments could integrate into a network of orbital platforms for space weather monitoring and communications relay to far-side surface lander and permanent base sites, e.g., for low-frequency radio cosmology and detection of exoplanet magnetospheres.

John F Cooper↗
NASA NTRS1993

A flattened cloud core in NGC 2024

The (J, K) (1, 1) and (2, 2) NH3 lines were mapped toward a molecular cloud core in NGC 2024 using the VLA in its C/D-configuration. This region is associated with one of the most highly collimated molecular outflows. We find that the molecular condensations associated with the far-infrared sources FIR 5, FIR 6, and FIR 7 have kinetic temperatures of about 40 K. We also find line broadening toward FIR 6 and FIR 7. This suggests that these condensations may not be protostars heated by gravitational energy released during collapse but that they have an internal heating source. A flattened structure of ammonia emission is found extending parallel to the unipolar CO outflow structure, but displaced systematically to the east. If the NH3 emission traces the denser gas environment, there is no evidence that a dense gas structure is confining the molecular outflow. Instead, the location of the high-velocity outflow along the surface of the NH3 structure suggests that a wind is sweeping material from the surface of this elongated cloud core.

Ho, Paul T. P.↗
DOE OSTI2025

Measurement of the Primary Beam of the Tianlai Cylindrical Antenna Using an Unmanned Aerial Vehicle

The Tianlai Cylinder Pathfinder Array consists of three adjacent cylindrical reflectors fixed on the ground, each 40 m long and 15 m wide, with the cylinder axis oriented along the North–South (N–S) direction. Dual linear polarization feeds are distributed along the focus line, parallel to the cylinder axis. Measurement of the primary beam profile of these cylindrical reflectors is difficult, as they are too large to be placed in an anechoic chamber. While the beam profile along the East–West (E–W) direction can be measured with the transit observations of bright astronomical radio sources, the beam profile along the N–S direction remains very uncertain. Here, we present a preliminary measurement of the beam profile of the Tianlai cylindrical antenna along both the N–S direction and E–W direction in the frequency range of 700–800 MHz, using a calibrator source carried by an unmanned aerial vehicle (UAV) flying in the far field. The beam profile of the Tianlai cylindrical antenna is determined from the analysis of the auto-correlation signals from the cylinder array correlator, taking into account the emitter antenna beam profile, itself measured with a dipole antenna on the ground. The accuracy of the UAV-based determination of the cylinder beam profiles is validated by comparing the results with the one derived from bright astronomical source transits, and with simulated beams.

Li, Jixia [Chinese Academy of Sciences (CAS), Beij↗