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At least 685 records · Page 38

Europe/United States space activities

Among the topics discussed are: the Olympus satellite program; trends in the Italian space technology; and ESA Space Station planning. Consideration is also given to cooperative international programs, including the Eurostar platform, the Tethered Satellite System, and the SPAS system; space science and applications programs; and the development of next generation space propulsion systems. Among the specific propulsion technologies discussed are: LOX/LR2 engines; the Ariane 5 solid propellant booster; and propulsion systems for earth-to-orbit vehicles.

Bainum, P. M.↗

Satellite power using magnetically suspended flywheel stack

Research activities with magnetically suspended flywheels are reported. The purpose of the effort is to critically examine and further the development of all the key technologies which impact the inertial energy storage system. The results presented discuss the concept of a magnetically suspended flywheel as it applies to a 500 Watt-hour energy storage system. The proposed system is currently under hardware development and is based upon two pancake magnetic bearings arranged in a vertical stack.

Kirk, James A.↗

Progress in MMIC technology for satellite communications

NASA's Lewis Research Center is actively involved in the development of monolithic microwave and millimeter-wave integrated circuits (MMICs). The approach of the program is to support basic research under grant or in-house, while MMIC development is done under contract, thereby facilitating the transfer of technology to users. Preliminary thrusts of the program have been the extension of technology to higher frequencies (60 GHz), degrees of complexity, and performance (power, efficiency, noise figure) by utilizing novel circuit designs, processes, and materials. A review of the progress made so far is presented.

Haugland, Edward J.↗

High Time Resolution Study of the Hemispheric Power Carried by Energetic Electrons Into the Ionosphere During the May 19-20, 1996, Auroral Activity

The UVI imager on board the POLAR satellite offers the opportunity to obtain high time resolution global auroral images. The spectral resolution of the imager is sufficient to separate the auroral emission from the scattered sunlight, even when the entire auroral zone is sunlit. The energy flux of the precipitating electrons is derived from the surface brightness through the LBH-long filter. Global images which have the dayglow removed are spatially integrated to yield the total hemispheric electron energy flux. This parameter, the hemispheric power, has found much application in ionospheric modeling. It can also be derived from electron spectra measured along the track of the NOAA/TIROS satellites that are combined with average empirical auroral precipitation patterns. We show that the hemispheric power input derived from the two-dimensional images represents a substantial improvement in the temporal variability of this parameter. We present an example for the period of 19/20 May 1996 by comparing power indices derived from NOAA/TIROS measurements with those derived from the UVI images.

Lummerzheim, D.↗

Solar/Stellar Irradiance Comparison Experiment (SOLSTICE) on the Upper Atmosphere Research Satellite (UARS)

A final report on the operational activities related to the UARS Solar Stellar irradiance Comparison Experiment (SOLSTICE) is presented. Scientific activities of SOLSTICE has also been supported. The UARS SOLSTICE originated at the University of Colorado in 1981. One year after the UARS launch in 1991, the operations and research support activities for SOLSTICE were moved to the High Altitude Observatory (HAO) of the National Center for Atmospheric Research (NCAR). The SOLSTICE program continued at HAO with the National Science Foundation, and after four years, it was moved once again back to the University of Colorado. At the University after 1997 this subject grant was issued to further extend the operations activities from July 2001 through September 2002. Although this is a final report for one particular activity, in fact the SOLSTICE operations activity -first at the University, then at HAO, and now again at the University -has continued in a seamless fashion.

Rottman, Gary J.↗

Global Night-Time Lights for Observing Human Activity

We present a concept for a small satellite mission to make systematic, global observations of night-time lights with spatial resolution suitable for discerning the extent, type and density of human settlements. The observations will also allow better understanding of fine scale fossil fuel CO2 emission distribution. The NASA Earth Science Decadal Survey recommends more focus on direct observations of human influence on the Earth system. The most dramatic and compelling observations of human presence on the Earth are the night light observations taken by the Defence Meteorological System Program (DMSP) Operational Linescan System (OLS). Beyond delineating the footprint of human presence, night light data, when assembled and evaluated with complementary data sets, can determine the fine scale spatial distribution of global fossil fuel CO2 emissions. Understanding fossil fuel carbon emissions is critical to understanding the entire carbon cycle, and especially the carbon exchange between terrestrial and oceanic systems.

Hipskind, Stephen R.↗

International Coordination and Support for SmallSat-enabled Space Weather Activities

Advances in space weather science and small satellite (SmallSat) technology have proceeded in parallel over the past two decades, but better communication and coordination is needed among the respective worldwide communities contributing to this rapid progress. We identify six areas where improved international coordination is especially desirable, including: (1) orbital debris mitigation; (2) spectrum management; (3) export control regulations; (4) access to timely and low-cost launch opportunities; (5) inclusive data policies; and (6) education. We argue the need for internationally coordinated policies and programs to promote the use of SmallSats for space weather research and forecasting while realizing maximum scientific and technical advances through the integration of these two increasingly important endeavors.

Teresa Nieves-Chinchilla↗

The X-ray Zurich environmental study (X-zens). I. Chandra and XMM-Newton observations of active galactic nuclei in galaxies in nearby groups

We describe X-ray observations with Chandra and XMM-Newton of 18 M {sub group} ∼ 1-6 × 10{sup 13} M {sub ☉}, z ∼ 0.05 galaxy groups from the Zurich ENvironmental Study. The X-ray data aim at establishing the frequency and properties, unaffected by host galaxy dilution and obscuration, of active galactic nuclei (AGNs) in central and satellite galaxies, also as a function of halo-centric distance. X-ray point-source detections are reported for 22 of the 177 galaxies, down to a sensitivity level of f {sub 0.5} {sub –} {sub 8} {sub keV} ∼ 5 × 10{sup –15} erg cm{sup –2} s{sup –1}, corresponding to a limiting luminosity of L {sub 0.5} {sub –} {sub 8} {sub keV} ∼ 3 × 10{sup 40} erg s{sup –1}. With the majority of the X-ray sources attributed to AGNs of low-to-moderate levels (L/L {sub Edd} ≳ 10{sup –4}), we discuss the detection rate in the context of the occupation of AGNs to halos of this mass scale and redshift and compare the structural and morphological properties between AGN-active and non-active galaxies. At galaxy mass scales <10{sup 11} M {sub ☉}, central galaxies appear to be a factor of ∼4 more likely to host AGNs than satellite galaxies of similar mass. This effect, coupled with the tendency for AGNs to be hosted by massive galaxies, explains the (weak) trend for AGNs to be preferentially found in the inner parts of group halos, with no detectable trend with halo-centric distance in the frequency of AGNs within the satellite population. Finally, our data indicate that the rate of decline with redshift of AGN activity in galaxy groups matches that of the global AGN population, indicating that either AGN activity occurs preferentially in group halos or that the evolution rate is independent of halo mass.

79 ASTRONOMY AND ASTROPHYSICS↗

Physical and Optical Characteristics of the October 2010 Haze Event Over Singapore: A Photometric and Lidar Analysis

Trans-boundary biomass burning smoke episodes have increased dramatically during the past 20-30 years and have become an annual phenomenon in the South‐East‐Asia region. On 15th October 2010, elevated levels of fire activity were detected by remote sensing satellites (e.g. MODIS). On the same date, measurements of fine particulate matter (PM2.5) at Singapore and Malaysia found high levels of fine mode particles in the local environment. All these observations were indicative of the initial onset of a smoke episode that lasted for several days. In this work, we investigate the temporal evolution of this smoke episode by analyzing the physical and optical properties of smoke particles with the aid of an AERONET Sun photometer, an MPLNet micropulse lidar, and surface PM2.5 measurements. Elevated levels of fire activity coupled with high aerosol optical depth and PM2.5 were observed over a period of nine days. Increased variability of parameters such as aerosol optical depth, Angstrom exponent number and its fine mode equivalents all indicated high levels of fine particulate presence in the atmosphere. Smoke particle growth due to aging, coagulation and condensation mechanisms was detected during the afternoons and over several days. Retrieved lidar ratios were compatible with the presence of fine particulate within the boundary/aerosol layer. Moreover, retrieved particle size distribution as well as single scattering albedo indicated the prevalence of the fine mode particulate regime as well as particles showing enhanced levels of absorption respectively.

Air quality↗

On the relationship of radar backscatter to wind speed and fetch

The physics of the interaction of electromagnetic waves with the ocean surface has been an active area of research for a number of years. This paper contains the results of satellite and aircraft experiments to investigate the ability of active microwave radars to infer surface wind speeds remotely. Data obtained from the recent National Aeronautics and Space Administration (NASA) Skylab experiment are compared with surface wind speeds measured by low-flying aircraft and ships-of-opportunity and found to give useful estimates of the ocean wind field. Also investigated was the influence of varying wave height on radar measurements of wind speed by measuring the backscattering cross-section for constant wind speed but variable wave conditions. It is found that this effect is of little importance.

Ross, D.↗

PC 4 - PC 1 magnetic pulsations at synchronous orbit and their relation to pulsations on the ground

Three types of Pc 4 pulsations with periods in the range 40-200 s have been identified in the ATS 6 satellite data. Two types are not observed on the ground. Both of these are accompanied by Pc 1-2 activity that is seen simultaneously both at the satellite and on the ground. One of these two types occurs during substorms and coincides with the development of the IPDP subtype of Pc 1-2. The other is observed in the magnetosphere during slow, smooth changes of the background magnetic field during the recovery phase of storms. Puslation amplitude for these two types is from 5 to several tens of nanoTeslas. The third type of Pc 4 pulsation has significantly smaller amplitudes in the magnetosphere and can be observed on the ground with amplitudes usually greater than in the magnetosphere. The properties of the first two types of long-period pulsations suggest that the mechanism for their generation is the drift-dissipative instability of the ring current plasma.

Maltseva, N.↗

Impact of Aquarius and SMAP Sea Surface Salinity Observations on Seasonal Predictions of the 2015 El Nino

We assess the impact of satellite sea surface salinity (SSS) observations on dynamical ENSO forecasts for the big 2015 El Nino event. From March to June 2015, the availability of two overlapping satellite SSS instruments, Aquarius and SMAP (Soil Moisture Active Passive Mission), allows a unique opportunity to compare and contrast forecasts generated with the benefit of these two satellite SSS observation types. Four distinct experiments are presented that include 1) freely evolving model SSS (i.e. no satellite SSS), relaxation to 2) climatological SSS (i.e. WOA13 SSS), 3) Aquarius, and 4) SMAP initialization. Coupled hindcasts are then generated from these initial conditions for March 2015. These forecasts are then validated against observations and evaluated with respect to the observed El Nino development.

Hackert, E.↗

The Combined Release and Radiation Effects Satellite (CRRES) program: A unique series of scientific experiments

The Defense Department and NASA have joined in a program to study the space environment which surrounds the earth and the effects of space radiation on modern satellite electronic systems. The Combined Release and Radiation Effects Satellite (CRRES) will carry an array of active experiments including chemical releases and a complement of sophisticated scientific instruments to accomplish these objectives. Other chemical release active experiments will be performed with sub-orbital rocket probes. The chemical releases will 'paint' the magnetic and electric fields of earthspace with clouds of glowing ions. Earthspace will be a laboratory, and the releases will be studied with an extensive network of ground-, aircraft-, and satellite-based diagnostic instruments. Some of the topics discussed include the following: the effects of earthspace; the need for active experiments; types of chemical releases; the CRRES program schedule; international support and coordinated studies; photographing chemical releases; information on locating chemical releases for observation by the amateur; and CRRES as a program.

Reasoner, David L.↗

Long-Term Variations in Total Solar Irradiance

For more than a decade total solar irradiance has been monitored simultaneously from space by different satellites. The detection of total solar irradiance variations by satellite -based experiments during the past decade and a half has stimulated modeling efforts to help identify their causes and to provide estimates of irradiance data, using "proxy" indicators of solar activity, for the time intervals when no satellite observations exist. In this paper the variations in total solar irradiance observed by the Nimbus-7/ERB, SMM/ACRIM I, and UARS/ACRIM II radiometers are compared to the changes in sunspot darkening and the enhanced emission of bright magnetic elements, including faculae and the magnetic network. Quantitative indices of sunspot darkening have been derived from the area and position of sunspots published in the NOAA-WDC Solar Geophysical Data catalog. The Mg core-to-wing ratio, derived from the irradiance observations of Nimbus-7 and NOAA9 satellites, is used as a proxy for the bright magnetic elements. It has been found that a model, calculated from the Mg II core-to-wing ratio underestimates the observed total irradiance at the time of maximum and during the beginning of the declining portion of solar cycle 22 similar in behaviour just before the maximum of solar cycle 21. Similar results are found using He-line equivalent width and 10.7 cm radio flux which indicates that the current irradiance models are in general not capable to reproducing the changes observed in total solar irradiance.

total↗

NASA’s Global Precipitation Measurement Mission: Leveraging Stakeholder Engagement & Applications Activities to Inform Decision-making

The application of satellite precipitation estimates from NASA’s Global Precipitation Measurement (GPM) Mission for decision-making has been a focus for the mission since launch. As a result, GPM data have enabled a range of applications that address societal needs, including water resource management, crop forecasting, ecological monitoring, disaster response, public health, aviation, weather forecasting, and climate modeling, among others. GPM applications activities have continued to focus on user engagement through in person trainings and interviews, workshops, webinars, and educational outreach activities. The goals of these efforts are to synthesize community data needs in order to effectively support and enable decision-making across agencies, academia and the global community. While these efforts have helped the GPM mission establish a large stakeholder community that encompasses federal and state partners, academic institutions, nd private and nonprofit companies, there remains difficulties associated with accessing, processing, and applying the data to support or enable applications. In this article, we present GPM applications strategies and approaches used to enhance the applications value of GPM data, and most importantly, demonstrate how these efforts have and can inform different decision-making contexts. This work also provides a discussion on key lessons learned from the user community and how this information can be utilized to help better support and shape applications approaches for future NASA Earth Science missions.

Satellite precipitation↗

Activity associated with the solar origin of coronal mass ejections

Solar coronal mass ejections (CMEs) observed in 1980 with the HAO Coronagraph/Polarimeter on the Solar Maximum Mission (SMM) satellite are compared with other forms of solar activity that might be physically related to the ejections. The solar phenomena checked and the method of association used were intentionally patterned after those of Munro et al.'s (1979) analysis of mass ejections observed with the Skylab coronagraph to facilitate comparison of the two epochs. Comparison of the results reveals that the types and degree of CME associations are similar near solar activity minimum and at maximum. For both epochs, most CMEs with associations had associated eruptive prominences, and the proportions of association of all types of activity were similar. A high percentage of association between SMM CMEs and X-ray long duration events is also found, in agreement with Skylab results. It is concluded that most CMEs are the result of the destabilization and eruption of a prominence and its overlying coronal structure, or of a magnetic structure capable of supporting a prominence.

Webb, D. F.↗

Pc 3 magnetic pulsations and precipitation of energetic electrons

The synchronous altitude satellite ATS 1 data and near-conjugate measurements of bremsstrahlung X-rays and ground magnetic variations were used to analyze an event of modulated auroral zone electron precipitation and magnetic pulsations in the Pc range. Transverse, azimuthal, nearly linearly polarized waves observed at ATS 1, ground magnetic pulsations at College, Alaska, and intervals of modulated electron precipitation centered on local magnetic moon, and noted in the X-ray data from Fort Yukon, Alaska, are discussed, noting that the origin of the Pc 3 waves is attributed to local field line resonances induced by Kelvin-Helmholtz instability at the magnetopause. The wave resonance model can explain observed differences in the pulsation activity at the ground, balloon, and satellite if account is taken of the spatial sensitivities of the techniques and the location of observing sites with respect to the probable location of resonant field lines. The data suggest that electron precipitation pulsations will correlate with Pc 3 magnetic pulsations when substorm injections coupled with azimuthal drift provide enhanced energetic particle fluxes with dayside resonance regions.

Arthur, C. W.↗

Applications of the TIROS-N sounding and cloud motion wind enhancement for the FGGE 'special effort'

In January of 1978, a panel of experts recommended that a 'special effort' be made to enhance and edit satellite soundings and cloud tracked winds in data sparse regions. It was felt that these activities would be necessary to obtain maximum benefits from an evaluation of satellite data during the Global Weather Experiment (FGGE). The 'special effort' is being conducted for the two special observing periods of FGGE. More than sixty cases have been selected for enhancement on the basis of meteorological interest. These cases include situations of blocking, cutoff low development, cyclogenesis, and tropical circulations. The sounding data enhancement process consists of supplementing the operational satellite sounding data set with higher resolution soundings in meteorologically active regions, and with new soundings where data voids or soundings of questionable quality exist.

Atlas, R.↗