Science.gov

Sample records for group e9 satellite

  1. Properties of satellite galaxies in nearby groups

    NASA Astrophysics Data System (ADS)

    Vennik, Jaan

    2016-10-01

    We studied the variation of stellar mass and various star-formation characteristics of satellite galaxies in a volume limited sample of nearby groups as a function of their group-centric distance and of their relative line-of-sight velocity in the group rest frame. We found clear radial dependencies, e.g. massive, red and passive satellites being distributed predominantly near the center of composite group. We also found some evidence of velocity modulation of star-forming properties of satellite galaxies near the group virial radius. We conclude that using kinematical data, it should be feasible to separate dynamical classes of bound, in-falling and 'backsplash' satellite galaxies.

  2. The global warming of group satellite galaxies

    NASA Astrophysics Data System (ADS)

    Yozin, C.; Bekki, K.

    2016-08-01

    Recent studies adopting λRe, a proxy for specific angular momentum, have highlighted how early-type galaxies (ETGs) are composed of two kinematical classes for which distinct formation mechanisms can be inferred. With upcoming surveys expected to obtain λRe from a broad range of environments (e.g. SAMI, MaNGA), we investigate in this numerical study how the λRe-ɛe distribution of fast-rotating dwarf satellite galaxies reflects their evolutionary state. By combining N-body/SPH simulations of progenitor disc galaxies (stellar mass ≃109 M⊙), their cosmologically-motivated sub-halo infall history and a characteristic group orbit/potential, we demonstrate the evolution of a satellite ETG population driven by tidal interactions (e.g. harassment). As a general result, these satellites remain intrinsically fast-rotating oblate stellar systems since their infall as early as z = 2; mis-identifications as slow rotators often arise due to a bar/spiral lifecycle which plays an integral role in their evolution. Despite the idealistic nature of its construction, our mock λRe-ɛe distribution at z < 0.1 reproduces its observational counterpart from the ATLAS3D/SAURON projects. We predict therefore how the observed λRe-ɛe distribution of a group evolves according to these ensemble tidal interactions.

  3. 78 FR 63459 - GPS Satellite Simulator Control Working Group Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-24

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF DEFENSE Air Force GPS Satellite Simulator Control Working Group Meeting AGENCY: Department of the Air Force. ACTION..., that the GPS Directorate will host a GPS Satellite Simulator Control Working Group (SSCWG) meeting on...

  4. 78 FR 67132 - GPS Satellite Simulator Control Working Group Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-08

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF DEFENSE Department of the Air Force GPS Satellite Simulator Control Working Group Meeting AGENCY: Space and Missile..., that the GPS Directorate will host a GPS Satellite Simulator Control Working Group (SSCWG) meeting on...

  5. 77 FR 70421 - GPS Satellite Simulator Control Working Group Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-26

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF DEFENSE Department of the Air Force GPS Satellite Simulator Control Working Group Meeting AGENCY: Space and Missile..., that the GPS Directorate will host a GPS Satellite Simulator Control Working Group (SSCWG) meeting...

  6. Group Task Force on Satellite Rescue and Repair

    NASA Astrophysics Data System (ADS)

    1992-09-01

    The Group Task Force was chartered by the Administrator of NASA to recommend 'a policy outlining the criteria, the design standards, and the pricing model to guide NASA in assessing the responsibilities for government and nongovernment Satellite Rescue and Repair Missions.' Criteria for accepting such missions, risks, and benefits to all sectors of our economy involved in satellite services, adequacy of planning and training, and the impact on NASA's primary mission were reviewed. The Group began by asking a more fundamental question; is satellite rescue and repair a logical element of NASA's mission? Factors considered were: (1) the probability of rescue or repair opportunities arising; (2) the economic justification for such attempts; (3) the benefits to NASA, both from such ad hoc learning experiences in space operations and the impact on the public perception of NASA; (4) the effect of such unanticipated missions on NASA's scheduled activities; (5) any potential effect on NASA's technical capability to work in space; and (6) any potential effect on U.S. economic competitiveness.

  7. Group Task Force on Satellite Rescue and Repair

    NASA Technical Reports Server (NTRS)

    1992-01-01

    The Group Task Force was chartered by the Administrator of NASA to recommend 'a policy outlining the criteria, the design standards, and the pricing model to guide NASA in assessing the responsibilities for government and nongovernment Satellite Rescue and Repair Missions.' Criteria for accepting such missions, risks, and benefits to all sectors of our economy involved in satellite services, adequacy of planning and training, and the impact on NASA's primary mission were reviewed. The Group began by asking a more fundamental question; is satellite rescue and repair a logical element of NASA's mission? Factors considered were: (1) the probability of rescue or repair opportunities arising; (2) the economic justification for such attempts; (3) the benefits to NASA, both from such ad hoc learning experiences in space operations and the impact on the public perception of NASA; (4) the effect of such unanticipated missions on NASA's scheduled activities; (5) any potential effect on NASA's technical capability to work in space; and (6) any potential effect on U.S. economic competitiveness.

  8. 42 CFR 52e.9 - Additional conditions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 1 2011-10-01 2011-10-01 false Additional conditions. 52e.9 Section 52e.9 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES GRANTS NATIONAL HEART, LUNG, AND BLOOD INSTITUTE GRANTS FOR PREVENTION AND CONTROL PROJECTS § 52e.9 Additional conditions. The...

  9. 42 CFR 52e.9 - Additional conditions.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 1 2012-10-01 2012-10-01 false Additional conditions. 52e.9 Section 52e.9 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES GRANTS NATIONAL HEART, LUNG, AND BLOOD INSTITUTE GRANTS FOR PREVENTION AND CONTROL PROJECTS § 52e.9 Additional conditions. The...

  10. 42 CFR 52e.9 - Additional conditions.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 1 2013-10-01 2013-10-01 false Additional conditions. 52e.9 Section 52e.9 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES GRANTS NATIONAL HEART, LUNG, AND BLOOD INSTITUTE GRANTS FOR PREVENTION AND CONTROL PROJECTS § 52e.9 Additional conditions. The...

  11. 42 CFR 52e.9 - Additional conditions.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 1 2014-10-01 2014-10-01 false Additional conditions. 52e.9 Section 52e.9 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES GRANTS NATIONAL HEART, LUNG, AND BLOOD INSTITUTE GRANTS FOR PREVENTION AND CONTROL PROJECTS § 52e.9 Additional conditions. The...

  12. 42 CFR 52e.9 - Additional conditions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Additional conditions. 52e.9 Section 52e.9 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES GRANTS NATIONAL HEART, LUNG, AND BLOOD INSTITUTE GRANTS FOR PREVENTION AND CONTROL PROJECTS § 52e.9 Additional conditions. The...

  13. 77 FR 23668 - GPS Satellite Simulator Working Group Notice of Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-20

    ... Department of the Air Force GPS Satellite Simulator Working Group Notice of Meeting AGENCY: The United States... Global Positioning Systems (GPS) Directorate will be hosting an open GPS Satellite Simulator Working... form a functioning GPS Satellite Simulator Working Group with industry and government...

  14. 77 FR 25150 - GPS Satellite Simulator Working Group; Notice of Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-27

    ... under 77 FR 23668. The date of the meeting will now be 15 May 2012 from 0730-1600 (Pacific Standard Time... Department of the Air Force GPS Satellite Simulator Working Group; Notice of Meeting AGENCY: The United... be hosting an open GPS Satellite Simulator Working Group (SSWG) meeting for manufacturers of...

  15. Satellites

    SciTech Connect

    Burns, J.A.; Matthews, M.S.

    1986-01-01

    The present work is based on a conference: Natural Satellites, Colloquium 77 of the IAU, held at Cornell University from July 5 to 9, 1983. Attention is given to the background and origins of satellites, protosatellite swarms, the tectonics of icy satellites, the physical characteristics of satellite surfaces, and the interactions of planetary magnetospheres with icy satellite surfaces. Other topics include the surface composition of natural satellites, the cratering of planetary satellites, the moon, Io, and Europa. Consideration is also given to Ganymede and Callisto, the satellites of Saturn, small satellites, satellites of Uranus and Neptune, and the Pluto-Charon system.

  16. QUENCHING OF STAR FORMATION IN SLOAN DIGITAL SKY SURVEY GROUPS: CENTRALS, SATELLITES, AND GALACTIC CONFORMITY

    SciTech Connect

    Knobel, Christian; Lilly, Simon J.; Woo, Joanna; Kovač, Katarina

    2015-02-10

    We re-examine the fraction of low-redshift Sloan Digital Sky Survey satellites and centrals in which star formation has been quenched, using the environment quenching efficiency formalism that separates out the dependence of stellar mass. We show that the centrals of the groups containing the satellites are responding to the environment in the same way as their satellites (at least for stellar masses above 10{sup 10.3} M {sub ☉}), and that the well-known differences between satellites and the general set of centrals arise because the latter are overwhelmingly dominated by isolated galaxies. The widespread concept of ''satellite quenching'' as the cause of environmental effects in the galaxy population can therefore be generalized to ''group quenching''. We then explore the dependence of the quenching efficiency of satellites on overdensity, group-centric distance, halo mass, the stellar mass of the satellite, and the stellar mass and specific star formation rate (sSFR) of its central, trying to isolate the effect of these often interdependent variables. We emphasize the importance of the central sSFR in the quenching efficiency of the associated satellites, and develop the meaning of this ''galactic conformity'' effect in a probabilistic description of the quenching of galaxies. We show that conformity is strong, and that it varies strongly across parameter space. Several arguments then suggest that environmental quenching and mass quenching may be different manifestations of the same underlying process. The marked difference in the apparent mass dependencies of environment quenching and mass quenching which produces distinctive signatures in the mass functions of centrals and satellites will arise naturally, since, for satellites at least, the distributions of the environmental variables that we investigate in this work are essentially independent of the stellar mass of the satellite.

  17. DID THE MILKY WAY DWARF SATELLITES ENTER THE HALO AS A GROUP?

    SciTech Connect

    Metz, Manuel; Kroupa, Pavel; Theis, Christian; Hensler, Gerhard; Jerjen, Helmut E-mail: pavel@astro.uni-bonn.de

    2009-05-20

    The dwarf satellite galaxies in the Local Group are generally considered to be hosted in dark matter subhalos that survived the disruptive processes during infall onto their host halos. It has recently been argued that if the majority of satellites entered the Milky Way (MW) halo in a group rather than individually, this could explain the spatial and dynamical peculiarities of its satellite distribution. Such groups were identified as dwarf galaxy associations that are found in the nearby universe. In this paper, we address the question whether galaxies in such associations can be the progenitors of the MW satellite galaxies. We find that the dwarf associations are much more extended than would be required to explain the disklike distribution of the MW and Andromeda satellite galaxies. We further identify a possible minor filamentary structure, perpendicular to the supergalactic plane, in which the dwarf associations are located, that might be related to the direction of infall of a progenitor galaxy of the MW satellites, if they are of tidal origin.

  18. Two Planes of Satellites in the Centaurus A Group

    NASA Astrophysics Data System (ADS)

    Tully, R. Brent; Libeskind, Noam I.; Karachentsev, Igor D.; Karachentseva, Valentina E.; Rizzi, Luca; Shaya, Edward J.

    2015-04-01

    Tip of the red giant branch measurements based on Hubble Space Telescope and ground-based imaging have resulted in accurate distances to 29 galaxies in the nearby Centaurus A Group. All but 2 of the 29 galaxies lie in either of two thin planes roughly parallel with the supergalactic equator. The planes are only slightly tilted from the line of sight, leaving little ambiguity regarding the morphology of the structure. The planes have characteristic rms long axis dimensions of ∼300 kpc and short axis dimensions of ∼60 kpc, hence axial ratios ∼0.2, and are separated in the short axis direction by 303 kpc.

  19. A study of the effect of group delay distortion on an SMSK satellite communications channel

    NASA Technical Reports Server (NTRS)

    Kerczewski, Robert J.

    1987-01-01

    The effects of group delay distortion on an SMSK satellite communications channel have been investigated. Software and hardware simulations have been used to determine the effects of channel group delay variations with frequency on the bit error rate for a 220 Mbps SMSK channel. These simulations indicate that group delay distortions can significantly degrade the bit error rate performance. The severity of the degradation is dependent on the amount, type, and spectral location of the group delay distortion.

  20. BRIGHTEST SATELLITE GALAXY ALIGNMENT OF SLOAN DIGITAL SKY SURVEY GALAXY GROUPS

    SciTech Connect

    Li Zhigang; Wang Yougang; Chen Xuelei; Yang Xiaohu; Xie Lizhi; Wang Xin E-mail: wangygcluster@gmail.com E-mail: lzxie@bao.ac.cn E-mail: wangxin@pha.jhu.edu

    2013-05-01

    We study the alignment signal between the distribution of the brightest satellite galaxies (BSGs) and the major axes of their host groups using the Sloan Digital Sky Survey group catalog constructed by Yang et al. After correcting for the effect of group ellipticity, a statistically significant ({approx}5{sigma}) major-axis alignment is detected and the alignment angle is found to be 43. Degree-Sign 0 {+-} 0. Degree-Sign 4. More massive and richer groups show a stronger BSG alignment. The BSG alignment around blue brightest central galaxies (BCGs) is slightly stronger than that around red BCGs. Red BSGs have a much stronger major-axis alignment than blue BSGs. Unlike BSGs, other satellites do not show very significant alignment with their group's major axis. We further explore BSG alignment using the semi-analytic model (SAM) constructed by Guo et al. In general, we found good agreement of the model with observations: BSGs in the SAM show a strong major-axis alignment that depends on group mass and richness in the same way as in observations and none of the other satellites exhibit prominent alignment. However, a discrepancy also exists in that the SAM shows a BSG color dependence opposite of that in observations, which is most probably induced by a missing large-scale environment ingredient in the SAM. The combination of two popular scenarios can explain the BSG alignment we detected. First, satellites merged into the group along the surrounding filaments, which are strongly aligned with the major axis of the group. Second, BSGs entered their host group more recently than other satellites, so they have preserved more information about their assembling history and major-axis alignment. In the SAM, we found positive evidence for the second scenario in the fact that BSGs merged into groups statistically more recently than other satellites. We also found that most of the BSGs (80%) were BCGs before they merged into groups and earlier merging BSGs tend to be closer to

  1. GALAXIES IN X-RAY GROUPS. III. SATELLITE COLOR AND MORPHOLOGY TRANSFORMATIONS

    SciTech Connect

    George, Matthew R.; Ma, Chung-Pei; Bundy, Kevin; Leauthaud, Alexie; Vulcani, Benedetta; Tinker, Jeremy; Wechsler, Risa H.; Finoguenov, Alexis

    2013-06-20

    While the star formation rates and morphologies of galaxies have long been known to correlate with their local environment, the process by which these correlations are generated is not well understood. Galaxy groups are thought to play an important role in shaping the physical properties of galaxies before entering massive clusters at low redshift, and transformations of satellite galaxies likely dominate the buildup of local environmental correlations. To illuminate the physical processes that shape galaxy evolution in dense environments, we study a sample of 116 X-ray selected galaxy groups at z = 0.2-1 with halo masses of 10{sup 13}-10{sup 14} M{sub Sun} and centroids determined with weak lensing. We analyze morphologies based on Hubble Space Telescope imaging and colors determined from 31 photometric bands for a stellar mass-limited population of 923 satellite galaxies and a comparison sample of 16,644 field galaxies. Controlling for variations in stellar mass across environments, we find significant trends in the colors and morphologies of satellite galaxies with group-centric distance and across cosmic time. Specifically at low stellar mass (log (M{sub *}/M{sub Sun }) = 9.8-10.3), the fraction of disk-dominated star-forming galaxies declines from >50% among field galaxies to <20% among satellites near the centers of groups. This decline is accompanied by a rise in quenched galaxies with intermediate bulge+disk morphologies, and only a weak increase in red bulge-dominated systems. These results show that both color and morphology are influenced by a galaxy's location within a group halo. We suggest that strangulation and disk fading alone are insufficient to explain the observed morphological dependence on environment, and that galaxy mergers or close tidal encounters must play a role in building up the population of quenched galaxies with bulges seen in dense environments at low redshift.

  2. The Himalia Satellite Group: A Case Study on the Dynamical Self-spreading of Families of Irregular Satellites and Asteroids

    NASA Astrophysics Data System (ADS)

    Li, Daohai; Christou, Apostolos A.

    2015-11-01

    Many of the outer planets' irregular satellites are grouped into families, thought to originate from collisional fragmentation (Nesvorný et al 2004, AJ). Interestingly, families associated with the largest irregulars are either more dispersed than expected (e.g. J6 Himalia; Nesvorný et al 2003, AJ), or do not exist at all (e.g. S9 Phoebe; Ćuk et al 2003, DDA meeting #34). Christou (2005, Icarus) found that gravitational scattering by Himalia of its own group could explain the large velocity dispersion found by Nesvorný et al (2003, AJ). At the same time, Christou identified a new type of dynamical mechanism that intermittently locks the node of the satellite J10 Lysithea to that of Himalia. The same mechanism, but due to Ceres, was recently found to operate within the Hoffmeister family, dispersing its members and allowing an estimate of its age (Novaković et al 2015, ApJ).Here we revisit the issue of family self-dispersion, aiming to better understand it by studying its effects on the Himalia group. For this we utilise (a) intensive test particle simulations on a larger scale than those by Christou (2005, Icarus) (b) a semi-analytical treatment of the new resonance based on the secular theory of coorbital motion by Namouni (1999, Icarus). This has allowed us to obtain firmer constraints on the rate of dispersion over time and on how the resonance affects the long-term evolution of the orbital elements. A principal result of this work is that particles near the resonance evolve differently than those away from it. During the meeting, we will present a new estimate of the family’s age as well as an analysis of the resonant structure and how it affects Himalia family members. We will also discuss the broader implications for the long-term evolution of orbital concentrations of small bodies in the solar system.Astronomical research at the Armagh Observatory is funded by the Northern Ireland Department of Culture, Arts and Leisure (DCAL).

  3. Benefits to satellite members in mixed-species foraging groups: an experimental analysis.

    PubMed

    Dolby; Grubb jr TC

    1998-08-01

    Hypotheses proposed to explain the formation of mixed-species foraging groups have focused on both foraging and antipredation benefits. Mixed-species flocks of bark-foraging birds form during the winter in the eastern deciduous forests of North America. These flocks are composed of two parid nuclear species, tufted titmice, Baeolophus bicolor, and either Carolina or black-capped chickadees, Poecile carolinensis or P. atricapillus, and several satellite species including downy woodpeckers, Picoides pubescens, and white-breasted nuthatches, Sitta carolinensis. The parid nuclear species seem to act as flock leaders and are closely followed by the satellite species. To elucidate what advantages downy woodpeckers and white-breasted nuthatches gain by flocking with parids, we removed parids from eight Ohio woodlots isolated by surrounding agricultural fields and compared the woodpeckers and nuthatches in these woodlots to those in eight controls. We tested four predictions generated by group-foraging hypotheses: compared with controls, satellite birds in treatment woodlots should (1) forage more in microclimates that reduce metabolic costs, (2) increase their vigilance, (3) exhibit reduced nutritional condition and (4) exhibit higher mortality rates. As predicted, female downy woodpeckers in treatment woodlots tended to forage in locations that were more sheltered from wind, presumably thereby reducing metabolic costs. Treatment males and females of both species significantly increased their vigilance. Finally, in the absence of parids, male nuthatches showed significantly reduced nutritional condition according to ptilochronology analysis of feathers grown during the experimental manipulation, and tended to exhibit increased mortality Copyright 1998 The Association for the Study of Animal Behaviour PMID:9787042

  4. Benefits to satellite members in mixed-species foraging groups: an experimental analysis.

    PubMed

    Dolby; Grubb jr TC

    1998-08-01

    Hypotheses proposed to explain the formation of mixed-species foraging groups have focused on both foraging and antipredation benefits. Mixed-species flocks of bark-foraging birds form during the winter in the eastern deciduous forests of North America. These flocks are composed of two parid nuclear species, tufted titmice, Baeolophus bicolor, and either Carolina or black-capped chickadees, Poecile carolinensis or P. atricapillus, and several satellite species including downy woodpeckers, Picoides pubescens, and white-breasted nuthatches, Sitta carolinensis. The parid nuclear species seem to act as flock leaders and are closely followed by the satellite species. To elucidate what advantages downy woodpeckers and white-breasted nuthatches gain by flocking with parids, we removed parids from eight Ohio woodlots isolated by surrounding agricultural fields and compared the woodpeckers and nuthatches in these woodlots to those in eight controls. We tested four predictions generated by group-foraging hypotheses: compared with controls, satellite birds in treatment woodlots should (1) forage more in microclimates that reduce metabolic costs, (2) increase their vigilance, (3) exhibit reduced nutritional condition and (4) exhibit higher mortality rates. As predicted, female downy woodpeckers in treatment woodlots tended to forage in locations that were more sheltered from wind, presumably thereby reducing metabolic costs. Treatment males and females of both species significantly increased their vigilance. Finally, in the absence of parids, male nuthatches showed significantly reduced nutritional condition according to ptilochronology analysis of feathers grown during the experimental manipulation, and tended to exhibit increased mortality Copyright 1998 The Association for the Study of Animal Behaviour

  5. VAST PLANES OF SATELLITES IN A HIGH-RESOLUTION SIMULATION OF THE LOCAL GROUP: COMPARISON TO ANDROMEDA

    SciTech Connect

    Gillet, N.; Ocvirk, P.; Aubert, D.; Knebe, A.; Yepes, G.; Libeskind, N.; Gottlöber, S.; Hoffman, Y.

    2015-02-10

    We search for vast planes of satellites (VPoS) in a high-resolution simulation of the Local Group performed by the CLUES project, which improves significantly the resolution of previous similar studies. We use a simple method for detecting planar configurations of satellites, and validate it on the known plane of M31. We implement a range of prescriptions for modeling the satellite populations, roughly reproducing the variety of recipes used in the literature, and investigate the occurrence and properties of planar structures in these populations. The structure of the simulated satellite systems is strongly non-random and contains planes of satellites, predominantly co-rotating, with, in some cases, sizes comparable to the plane observed in M31 by Ibata et al. However, the latter is slightly richer in satellites, slightly thinner, and has stronger co-rotation, which makes it stand out as overall more exceptional than the simulated planes, when compared to a random population. Although the simulated planes we find are generally dominated by one real structure forming its backbone, they are also partly fortuitous and are thus not kinematically coherent structures as a whole. Provided that the simulated and observed planes of satellites are indeed of the same nature, our results suggest that the VPoS of M31 is not a coherent disk and that one-third to one-half of its satellites must have large proper motions perpendicular to the plane.

  6. Report of the IAU Working Group on Cartographic Coordinates and Rotational Elements of the Planets and Satellites

    USGS Publications Warehouse

    Davies, M.E.; Abalakin, V.K.; Cross, C.A.; Duncombe, R.L.; Masursky, H.; Morando, B.; Owen, T.C.; Seidelmann, P.K.; Sinclair, A.T.; Wilkins, G.A.; Tjuflin, Y.S.

    1980-01-01

    This paper is the entire report of the IAU Working Group on Cartographic Coordinates and Rotational Elements of the Planets and Satellites, including three annexes. Tables give the recemmended values for the directions of the north poles of rotation and the prime meridians of the planets and satellites. Reference surfaces for mapping these bodies are described. The annexes discuss the guiding principles, given in the body of the report, present explanatory notes, and provide a bibliography of the rotational elements and reference surfaces of the planets and satellites, definitions, and algebraic expressions of relevant parameters. ?? 1980 D. Reidel Publishing Co.

  7. On the spin bias of satellite galaxies in the local group-like environment

    SciTech Connect

    Lee, Jounghun; Lemson, Gerard E-mail: lemson@mpa-garching.mpg.de

    2013-05-01

    We utilize the Millennium-II simulation databases to study the spin bias of dark subhalos in the Local Group-like systems which have two prominent satellites with comparable masses. Selecting the group-size halos with total mass similar to that of the Local Group (LG) from the friends-of-friends halo catalog and locating their subhalos from the substructure catalog, we determine the most massive (main) and second to the most massive (submain) ones among the subhalos hosted by each selected halo. When the dimensionless spin parameter (λ) of each subhalo is derived from its specific angular momentum and circular velocity at virial radius, a signal of correlation is detected between the spin parameters of the subhalos and the main-to-submain mass ratios of their host halos at z = 0: the higher main-to-submain mass ratio a host halo has, the higher mean spin parameter its subhalos have. It is also found that the correlations exist even for the subhalo progenitors at z = 0.5 and 1. Our interpretation of this result is that the subhalo spin bias is not a transient effect but an intrinsic property of a LG-like system with higher main-to- submain mass ratio, caused by stronger anisotropic stress in the region. A cosmological implication of our result is also discussed.

  8. The masses of satellites in GAMA galaxy groups from 100 square degrees of KiDS weak lensing data

    NASA Astrophysics Data System (ADS)

    Sifón, Cristóbal; Cacciato, Marcello; Hoekstra, Henk; Brouwer, Margot; van Uitert, Edo; Viola, Massimo; Baldry, Ivan; Brough, Sarah; Brown, Michael J. I.; Choi, Ami; Driver, Simon P.; Erben, Thomas; Grado, Aniello; Heymans, Catherine; Hildebrandt, Hendrik; Joachimi, Benjamin; de Jong, Jelte T. A.; Kuijken, Konrad; McFarland, John; Miller, Lance; Nakajima, Reiko; Napolitano, Nicola; Norberg, Peder; Robotham, Aaron S. G.; Schneider, Peter; Kleijn, Gijs Verdoes

    2015-12-01

    We use the first 100 deg2 of overlap between the Kilo-Degree Survey and the Galaxy And Mass Assembly survey to determine the average galaxy halo mass of ˜10 000 spectroscopically confirmed satellite galaxies in massive (M > 1013 h-1 M⊙) galaxy groups. Separating the sample as a function of projected distance to the group centre, we jointly model the satellites and their host groups with Navarro-Frenk-White density profiles, fully accounting for the data covariance. The probed satellite galaxies in these groups have total masses log ≈ 11.7-12.2 consistent across group-centric distance within the errorbars. Given their typical stellar masses, log ˜ 10.5, such total masses imply stellar mass fractions of / ≈ 0.04 h-1. The average subhalo hosting these satellite galaxies has a mass Msub ˜ 0.015Mhost independent of host halo mass, in broad agreement with the expectations of structure formation in a Λ cold dark matter universe.

  9. Report of the IAU working group on cartographic coordinates and rotational elements of the planets and satellites - 1982

    NASA Astrophysics Data System (ADS)

    Davies, M. E.; Abalakin, V. K.; Lieske, J. H.; Seidelmann, P. K.; Sinclair, A. T.; Sinzi, A. M.; Smith, B. A.; Tjuflin, Y. S.

    1983-04-01

    This paper contains the report of the IAU Working Group on Cartographic Coordinates and Rotational Elements of the Planets and Satellites as presented at the XVIII General Assembly held at Patras, Greece, 1982. Tables give the recommended values for the direction of the north poles of rotation and the prime meridians of the planets and satellites referred to both the B1950 and J2000 standard coordinate systems. Reference surfaces for mapping these bodies are described. An appendix discusses the principal changes to the tables since 1979.

  10. Satellite altimetric measurements of the ocean. Report of the TOPEX Science Working Group

    NASA Technical Reports Server (NTRS)

    Stewart, R.

    1981-01-01

    The scientific usefulness of satellite measurements of ocean topography for the study of ocean circulation was investigated. The following topics were studied: (1) scientific problems which use altimetric measurements of ocean topography; (2) the extent in which in situ measurements are complementary or required; (3) accuracy, precision, and spatial and temporal resolutions which are required of the topographic measurements; (4) errors associated with measurement techniques; and (5) influences of these errors on scientific problems. An operational system for measuring ocean topography, was defined and the cost of conducting such a topographic experiment, was estimated.

  11. Cyberinfrastructure Initiatives of the Committee on Earth Observation Satellites (CEOS) Working Group on Information Systems and Services (WGISS)

    NASA Astrophysics Data System (ADS)

    McDonald, K. R.; Faundeen, J. L.; Petiteville, I.

    2005-12-01

    The Committee on Earth Observation Satellites (CEOS) was established in 1984 in response to a recommendation from the Economic Summit of Industrialized Nations Working Group on Growth, Technology, and Employment's Panel of Experts on Satellite Remote Sensing. CEOS participants are Members, who are national or international governmental organizations who operate civil spaceborne Earth observation satellites, and Associates who are governmental organizations with civil space programs in development or international scientific or governmental bodies who have an interest in and support CEOS objectives. The primary objective of CEOS is to optimize benefits of satellite Earth observations through cooperation of its participants in mission planning and in development of compatible data products, formats, services, applications and policies. To pursue its objectives, CEOS establishes working groups and associated subgroups that focus on relevant areas of interest. While the structure of CEOS has evolved over its lifetime, today there are three permanent working groups. One is the Working Group on Calibration and Validation that addresses sensor-specific calibration and validation and geophysical parameter validation. A second is the Working Group on Education, Training, and Capacity Building that facilitates activities that enhance international education and training in Earth observation techniques, data analysis, interpretation and applications, with a particular focus on developing countries. The third permanent working group is the Working Group on Information Systems and Services (WGISS). The purpose of WGISS is to promote collaboration in the development of the systems and services based on international standards that manage and supply the Earth observation data and information from participating agencies' missions. WGISS places great emphasis on the use of demonstration projects involving user groups to solve the critical interoperability issues associated with the

  12. Observations of Environmental Quenching in Groups in the 11 GYR Since z = 2.5: Different Quenching For Central and Satellite Galaxies

    NASA Technical Reports Server (NTRS)

    Tal, Tomer; Dekel, Avishai; Marchesini, Danilo; Momcheva, Ivelina; Nelson, Erica J.; Patel, Shannon G.; Quadri, Ryan F.; Rix, Hans-Walter; Skelton, Rosalind E.; Wake, David A.; Whitaker, Katherine E.; Oesch, Pascal; Muzzin, Adam; Brammer, Gabriel B.; vanDokkum, Peter G.; Franx, Marijn; Illingworth, Garth D.; Leja, Joel; Magee, Daniel

    2014-01-01

    We present direct observational evidence for star formation quenching in galaxy groups in the redshift range 0 less than z less than 2.5. We utilize a large sample of nearly 6000 groups, selected by fixed cumulative number density from three photometric catalogs, to follow the evolving quiescent fractions of central and satellite galaxies over roughly 11 Gyr. At z approximately 0, central galaxies in our sample range in stellar mass from Milky Way/M31 analogs (M=6.5x10(exp 10) M/solar mass) to nearby massive ellipticals (M=1.5x10(exp 11) M/solar mass). Satellite galaxies in the same groups reach masses as low as twice that of the Large Magellanic Cloud (M=6.5x10(exp 9) M/solar mass). Using statistical background subtraction, we measure the average rest-frame colors of galaxies in our groups and calculate the evolving quiescent fractions of centrals and satellites over seven redshift bins. Our analysis shows clear evidence for star formation quenching in group halos, with a different quenching onset for centrals and their satellite galaxies. Using halo mass estimates for our central galaxies, we find that star formation shuts off in centrals when typical halo masses reach between 10(exp 12) and 10(exp 13) M/solar mass, consistent with predictions from the halo quenching model. In contrast, satellite galaxies in the same groups most likely undergo quenching by environmental processes, whose onset is delayed with respect to their central galaxy. Although star formation is suppressed in all galaxies over time, the processes that govern quenching are different for centrals and satellites. While mass plays an important role in determining the star formation activity of central galaxies, quenching in satellite galaxies is dominated by the environment in which they reside.

  13. Observations of environmental quenching in groups in the 11 Gyr since z = 2.5: Different quenching for central and satellite galaxies

    SciTech Connect

    Tal, Tomer; Illingworth, Garth D.; Magee, Daniel; Oesch, Pascal; Van Dokkum, Pieter G.; Leja, Joel; Momcheva, Ivelina; Nelson, Erica J.; Muzzin, Adam; Franx, Marijn; Brammer, Gabriel B.; Marchesini, Danilo; Patel, Shannon G.; Quadri, Ryan F.; Rix, Hans-Walter; Skelton, Rosalind E.; Wake, David A.; Whitaker, Katherine E.

    2014-07-10

    We present direct observational evidence for star formation quenching in galaxy groups in the redshift range 0 < z < 2.5. We utilize a large sample of nearly 6000 groups, selected by fixed cumulative number density from three photometric catalogs, to follow the evolving quiescent fractions of central and satellite galaxies over roughly 11 Gyr. At z ∼ 0, central galaxies in our sample range in stellar mass from Milky Way/M31 analogs (M{sub *}/M{sub ☉} = 6.5 × 10{sup 10}) to nearby massive ellipticals (M{sub *}/M{sub ☉} = 1.5 × 10{sup 11}). Satellite galaxies in the same groups reach masses as low as twice that of the Large Magellanic Cloud (M{sub *}/M{sub ☉} = 6.5 × 10{sup 9}). Using statistical background subtraction, we measure the average rest-frame colors of galaxies in our groups and calculate the evolving quiescent fractions of centrals and satellites over seven redshift bins. Our analysis shows clear evidence for star formation quenching in group halos, with a different quenching onset for centrals and their satellite galaxies. Using halo mass estimates for our central galaxies, we find that star formation shuts off in centrals when typical halo masses reach between 10{sup 12} and 10{sup 13} M{sub ☉}, consistent with predictions from the halo quenching model. In contrast, satellite galaxies in the same groups most likely undergo quenching by environmental processes, whose onset is delayed with respect to their central galaxy. Although star formation is suppressed in all galaxies over time, the processes that govern quenching are different for centrals and satellites. While mass plays an important role in determining the star formation activity of central galaxies, quenching in satellite galaxies is dominated by the environment in which they reside.

  14. THE ZURICH ENVIRONMENTAL STUDY (ZENS) OF GALAXIES IN GROUPS ALONG THE COSMIC WEB. II. GALAXY STRUCTURAL MEASUREMENTS AND THE CONCENTRATION OF MORPHOLOGICALLY CLASSIFIED SATELLITES IN DIVERSE ENVIRONMENTS

    SciTech Connect

    Cibinel, A.; Carollo, C. M.; Lilly, S. J.; Miniati, F.; Cameron, E.; Peng, Y.; Pipino, A.; Rudick, C. S.; Silverman, J. D.; Van Gorkom, J. H.; Finoguenov, A.; Norberg, P. E-mail: marcella@phys.ethz.ch

    2013-10-20

    We present structural measurements for the galaxies in the 0.05 < z < 0.0585 groups of the Zurich Environmental Study, aimed at establishing how galaxy properties depend on four environmental parameters: group halo mass (M{sub GROUP}), group-centric distance (R/R{sub 200}), ranking into central or satellite, and large-scale structure density (δ{sub LSS}). Global galaxy structure is quantified both parametrically and non-parametrically. We correct all these measurements for observational biases due to point-spread function blurring and surface brightness effects as a function of galaxy size, magnitude, steepness of light profile, and ellipticity. Structural parameters are derived also for bulges, disks, and bars. We use the galaxy bulge-to-total ratios (B/T) together with the calibrated non-parametric structural estimators to implement a quantitative morphological classification that maximizes purity in the resulting morphological samples. We investigate how the concentration C of satellite galaxies depends on galaxy mass for each Hubble type and on M{sub GROUP}, R/R{sub 200}, and δ{sub LSS}. At galaxy masses M ≥ 10{sup 10} M{sub ☉}, the concentration of disk satellites increases with increasing stellar mass separately within each morphological bin of B/T. The known increase in concentration with stellar mass for disk satellites is thus due, at least in part, to an increase in galaxy central stellar density at constant B/T. The correlation between concentration and galaxy stellar mass becomes progressively steeper for later morphological types. The concentration of disk satellites shows a barely significant dependence on δ{sub LSS} or R/R{sub 200}. The strongest environmental effect is found with group mass for >10{sup 10} M{sub ☉} disk-dominated satellites, which are ∼10% more concentrated in high mass groups than in lower mass groups.

  15. Distance Education: One Way Television with Simultaneous Telephone Group Conferencing Using Satellite Maps as a Monitoring Device. A Report to the Innovative Projects Fund.

    ERIC Educational Resources Information Center

    Kirman, Joseph M.; Goldberg, Jack

    This study compared teachers instructed in use of Landsat satellite maps through one-way television and simultaneous telephone group conferencing to another teacher group instructed directly. Thirty teachers of intermediate children in Edmonton and Sherwood Park, Alberta, received 5 hours of instruction about Landsat maps over a 2-week period;…

  16. A muscle stem cell for every muscle: variability of satellite cell biology among different muscle groups

    PubMed Central

    Randolph, Matthew E.; Pavlath, Grace K.

    2015-01-01

    The human body contains approximately 640 individual skeletal muscles. Despite the fact that all of these muscles are composed of striated muscle tissue, the biology of these muscles and their associated muscle stem cell populations are quite diverse. Skeletal muscles are affected differentially by various muscular dystrophies (MDs), such that certain genetic mutations specifically alter muscle function in only a subset of muscles. Additionally, defective muscle stem cells have been implicated in the pathology of some MDs. The biology of muscle stem cells varies depending on the muscles with which they are associated. Here we review the biology of skeletal muscle stem cell populations of eight different muscle groups. Understanding the biological variation of skeletal muscles and their resident stem cells could provide valuable insight into mechanisms underlying the susceptibility of certain muscles to myopathic disease. PMID:26500547

  17. Secular resonances between bodies on close orbits: a case study of the Himalia prograde group of jovian irregular satellites

    NASA Astrophysics Data System (ADS)

    Li, Daohai; Christou, Apostolos A.

    2016-06-01

    The gravitational interaction between two objects on similar orbits can effect noticeable changes in the orbital evolution even if the ratio of their masses to that of the central body is vanishingly small. Christou (Icarus 174:215-229, 2005) observed an occasional resonant lock in the differential node Δ Ω between two members in the Himalia irregular satellite group of Jupiter in the N-body simulations (corresponding mass ratio ˜ 10^{-9}). Using a semianalytical approach, we have reproduced this phenomenon. We also demonstrate the existence of two additional types of resonance, involving angle differences Δ ω and Δ (Ω +π) between two group members. These resonances cause secular oscillations in eccentricity and/or inclination on timescales ˜ 1 Myr. We locate these resonances in ( a, e, i) space and analyse their topological structure. In subsequent N-body simulations, we confirm these three resonances and find a fourth one involving Δ π. In addition, we study the occurrence rates and the stability of the four resonances from a statistical perspective by integrating 1000 test particles for 100 Myr. We find ˜ 10 to 30 librators for each of the resonances. Particularly, the nodal resonance found by Christou is the most stable: 2 particles are observed to stay in libration for the entire integration.

  18. Solution structure of the C-terminal domain of Ole e 9, a major allergen of olive pollen

    PubMed Central

    Treviño, Miguel Á.; Palomares, Oscar; Castrillo, Inés; Villalba, Mayte; Rodríguez, Rosalía; Rico, Manuel; Santoro, Jorge; Bruix, Marta

    2008-01-01

    Ole e 9 is an olive pollen allergen belonging to group 2 of pathogenesis-related proteins. The protein is composed of two immunological independent domains: an N-terminal domain (NtD) with 1,3-β-glucanase activity, and a C-terminal domain (CtD) that binds 1,3-β-glucans. We have determined the three-dimensional structure of CtD-Ole e 9 (101 amino acids), which consists of two parallel α-helices forming an angle of ∼55°, a small antiparallel β-sheet with two short strands, and a 3–10 helix turn, all connected by long coil segments, resembling a novel type of folding among allergens. Two regions surrounded by aromatic residues (F49, Y60, F96, Y91 and Y31, H68, Y65, F78) have been localized on the protein surface, and a role for sugar binding is suggested. The epitope mapping of CtD-Ole e 9 shows that B-cell epitopes are mainly located on loops, although some of them are contained in secondary structural elements. Interestingly, the IgG and IgE epitopes are contiguous or overlapped, rather than coincident. The three-dimensional structure of CtD-Ole e 9 might help to understand the underlying mechanism of its biochemical function and to determine possible structure–allergenicity relationships. PMID:18096638

  19. THE ZURICH ENVIRONMENTAL STUDY (ZENS) OF GALAXIES IN GROUPS ALONG THE COSMIC WEB. V. PROPERTIES AND FREQUENCY OF MERGING SATELLITES AND CENTRALS IN DIFFERENT ENVIRONMENTS

    SciTech Connect

    Pipino, A.; Cibinel, A.; Tacchella, S.; Carollo, C. M.; Lilly, S. J.; Miniati, F.; Silverman, J. D.; Van Gorkom, J. H.; Finoguenov, A.

    2014-12-20

    We use the Zurich Environmental Study database to investigate the environmental dependence of the merger fraction Γ and merging galaxy properties in a sample of ∼1300 group galaxies with M > 10{sup 9.2} M {sub ☉} and 0.05 < z < 0.0585. In all galaxy mass bins investigated in our study, we find that Γ decreases by a factor of ∼2-3 in groups with halo masses M {sub HALO} > 10{sup 13.5} M {sub ☉} relative to less massive systems, indicating a suppression of merger activity in large potential wells. In the fiducial case of relaxed groups only, we measure a variation of ΔΓ/Δlog (M {sub HALO}) ∼ –0.07 dex{sup –1}, which is almost independent of galaxy mass and merger stage. At galaxy masses >10{sup 10.2} M {sub ☉}, most mergers are dry accretions of quenched satellites onto quenched centrals, leading to a strong increase of Γ with decreasing group-centric distance at these mass scales. Both satellite and central galaxies in these high-mass mergers do not differ in color and structural properties from a control sample of nonmerging galaxies of equal mass and rank. At galaxy masses of <10{sup 10.2} M {sub ☉} where we mostly probe satellite-satellite pairs and mergers between star-forming systems close pairs (projected distance <10-20 kpc) show instead ∼2 × enhanced (specific) star formation rates and ∼1.5 × larger sizes than similar mass, nonmerging satellites. The increase in both size and star formation rate leads to similar surface star formation densities in the merging and control-sample satellite populations.

  20. Satellites for distress alerting and locating: Report by Interagency Committee for Search and Rescue Ad Hoc Working Group

    NASA Technical Reports Server (NTRS)

    Ehrlich, E.

    1976-01-01

    The background behind the congressional legislation that led to the requirement for the Emergency Locator Transmitter (ELT) and the Emergency Position-Indicating Radio Beacon (EPIRB) to be installed on certain types of aircraft and inspected marine vessels respectively is discussed. The DAL problem is discussed for existing ELT and EPIRB equipped aircraft and ships. It is recognized that the DAL requirement for CONUS and Alaska and the maritime regions are not identical. In order to address the serious DAL problem which currently exists in CONUS and Alaska, a low orbiting satellite system evolves as the most viable and cost effective alternative that satisfies the overall SAR system design requirements. A satellite system designed to meet the needs of the maritime regions could be either low orbiting or geostationary. The conclusions drawn from this report support the recommendation to proceed with the implementation of a SAR orbiting satellite system.

  1. Satellite data relay and platform locating in oceanography. Report of the In Situ Ocean Science Working Group

    NASA Technical Reports Server (NTRS)

    Chase, R.; Cote, C.; Davis, R. E.; Dugan, J.; Frame, D. D.; Halpern, D.; Kerut, E.; Kirk, R.; Mcgoldrick, L.; Mcwilliams, J. C.

    1983-01-01

    The present and future use of satellites to locate offshore platforms and relay data from in situ sensors to shore was examined. A system of the ARGOS type will satisfy the increasing demand for oceanographic information through data relay and platform location. The improved ship navigation provided by the Global Positioning System (GPS) will allow direct observation of currents from underway ships. Ocean systems are described and demand estimates on satellite systems are determined. The capabilities of the ARGOS system is assessed, including anticipated demand in the next decade.

  2. Enzymological characterization of the nuclease domain from the bacterial toxin colicin E9 from Escherichia coli.

    PubMed

    Pommer, A J; Wallis, R; Moore, G R; James, R; Kleanthous, C

    1998-09-01

    The cytotoxicity of the bacterial toxin colicin E9 is due to a non-specific DNase that penetrates the cytoplasm of the infected organism and causes cell death. We report the first enzymological characterization of the overexpressed and purified 15 kDa DNase domain (E9 DNase) from this class of toxin. CD spectroscopy shows the E9 DNase to be structured in solution, and analytical ultracentrifugation data indicate that the enzyme is a monomer. The nuclease activity of the E9 DNase was compared with the well-studied, non-specific DNase I by using a spectrophotometric assay with calf thymus DNA as the substrate. Both enzymes require divalent metal ions for activity but, unlike DNase I, the E9 DNase is not activated by Ca2+ ions. Somewhat surprisingly, the E9 DNase shows optimal activity and linear kinetics in the presence of transition metals such as Ni2+ and Co2+ but displays non-linear kinetics with metals such as Mg2+ and Ca2+. Conversely, Ni2+ and other transition metals showed poor activity in a plasmid-based nicking assay, yielding significant amounts of linearized plasmid, whereas Mg2+ was very active, with the main intermediate being open-circle DNA. The results suggest that, on entry into bacterial cells, the E9 DNase is likely to exhibit primarily Mg2+-dependent nicking activity against chromosomal DNA, although other metals could also be utilized to introduce both single- and double-strand cleavages.

  3. Enzymological characterization of the nuclease domain from the bacterial toxin colicin E9 from Escherichia coli.

    PubMed Central

    Pommer, A J; Wallis, R; Moore, G R; James, R; Kleanthous, C

    1998-01-01

    The cytotoxicity of the bacterial toxin colicin E9 is due to a non-specific DNase that penetrates the cytoplasm of the infected organism and causes cell death. We report the first enzymological characterization of the overexpressed and purified 15 kDa DNase domain (E9 DNase) from this class of toxin. CD spectroscopy shows the E9 DNase to be structured in solution, and analytical ultracentrifugation data indicate that the enzyme is a monomer. The nuclease activity of the E9 DNase was compared with the well-studied, non-specific DNase I by using a spectrophotometric assay with calf thymus DNA as the substrate. Both enzymes require divalent metal ions for activity but, unlike DNase I, the E9 DNase is not activated by Ca2+ ions. Somewhat surprisingly, the E9 DNase shows optimal activity and linear kinetics in the presence of transition metals such as Ni2+ and Co2+ but displays non-linear kinetics with metals such as Mg2+ and Ca2+. Conversely, Ni2+ and other transition metals showed poor activity in a plasmid-based nicking assay, yielding significant amounts of linearized plasmid, whereas Mg2+ was very active, with the main intermediate being open-circle DNA. The results suggest that, on entry into bacterial cells, the E9 DNase is likely to exhibit primarily Mg2+-dependent nicking activity against chromosomal DNA, although other metals could also be utilized to introduce both single- and double-strand cleavages. PMID:9716496

  4. 5. Building E9; view of top of wash tank showing ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. Building E-9; view of top of wash tank showing agitator and RDX line entering tank; third floor, looking NW. (Harms and Ryan) - Holston Army Ammunition Plant, RDX-and-Composition-B Manufacturing Line 9, Kingsport, Sullivan County, TN

  5. A focus group study of factors that promote and constrain the use of satellite-derived fire products by resource managers in southern Africa.

    PubMed

    Trigg, S N; Roy, D P

    2007-01-01

    Semi-structured focus group interviews were employed to examine factors that affect the likelihood that resource managers in southern Africa will use information on vegetation fires provided by two satellite-derived products: an active fire product and a burned area product. The two products are updated regularly and aim to deliver the state-of-the-art in the global monitoring of fires from satellite remote-sensing. Both products are derived from data transmitted by the Moderate Resolution Imaging Spectroradiometer (MODIS) sensors carried onboard NASA's Aqua and Terra satellites. The active fire product can be accessed for free via the internet and on media by users working anywhere in the world; the burned area product will be accessible in a similar manner in 2006. The MODIS fire products provide systematic, near-global coverage and are freely available; as such, they give resource managers new opportunities to obtain or supplement information they need to manage vegetation fires effectively. However, the availability of these products does not mean that resource managers will use them, and many other factors are involved. To understand factors that affect whether southern African resource managers will use the two products, two focus groups were held with members of the Southern African Fire Network (SAFNet) in Malawi, Africa, August 2004. Analysis of the group discussions reveals a number of factors that influence whether they will use the products. The qualitative, in depth nature of the group discussions revealed 12 main factors that influence product use; not least the low international internet bandwidths for African countries outside of South Africa. Analysis of the group discussions also suggests how the uptake of MODIS fire products by resource managers in southern Africa might be enhanced by affecting specific changes to how MODIS products are packaged and delivered.

  6. Characterisation of a mobile protein-binding epitope in the translocation domain of colicin E9.

    PubMed

    Macdonald, Colin J; Tozawa, Kaeko; Collins, Emily S; Penfold, Christopher N; James, Richard; Kleanthous, Colin; Clayden, Nigel J; Moore, Geoffrey R

    2004-09-01

    The 61 kDa colicin E9 protein toxin enters the cytoplasm of susceptible cells by interacting with outer membrane and periplasmic helper proteins, and kills them by hydrolysing their DNA. The membrane translocation function is located in the N-terminal domain of the colicin, with a key signal sequence being a pentapeptide region that governs the interaction with the helper protein TolB (the TolB box). Previous NMR studies (Collins et al., 2002 J. Mol. Biol. 318, 787-804) have shown that the N-terminal 83 residues of colicin E9, which includes the TolB box, is largely unstructured and highly flexible. In order to further define the properties of this region we have studied a fusion protein containing residues 1-61 of colicin E9 connected to the N-terminus of the E9 DNase by an eight-residue linking sequence. 53 of the expected 58 backbone NH resonances for the first 61 residues and all of the expected 7 backbone NH resonances of the linking sequence were assigned with 3D (1)H-(13)C-(15)N NMR experiments, and the backbone dynamics of these regions investigated through measurement of (1)H-(15)N relaxation properties. Reduced spectral density mapping, extended Lipari-Szabo modelling, and fitting backbone R(2) relaxation rates to a polymer dynamics model identifies three clusters of interacting residues, each containing a tryptophan. Each of these clusters is perturbed by TolB binding to the intact colicin, showing that the significant region for TolB binding extends beyond the recognized five amino acids of the TolB box and demonstrating that the binding epitope for TolB involves a considerable degree of order within an otherwise disordered and flexible domain. Abbreviations : Im9, the immunity protein for colicin E9; E9 DNase, the endonuclease domain of colicin E9; HSQC, heteronuclear single quantum coherence; ppm, parts per million; DSS, 2,2-(dimethylsilyl)propanesulfonic acid; TSP, sodium 3-trimethylsilypropionate; T(1 - 61)-DNase fusion protein, residues 1-61 of

  7. Mutagenic scan of the H-N-H motif of colicin E9: implications for the mechanistic enzymology of colicins, homing enzymes and apoptotic endonucleases

    PubMed Central

    Walker, David C.; Georgiou, Theonie; Pommer, Ansgar J.; Walker, Daniel; Moore, Geoffrey R.; Kleanthous, Colin; James, Richard

    2002-01-01

    Colicin E9 is a microbial toxin that kills bacteria through random degradation of chromosomal DNA. Within the active site of the cytotoxic endonuclease domain of colicin E9 (the E9 DNase) is a 32 amino acid motif found in the H-N-H group of homing endonucleases. Crystal structures of the E9 DNase have implicated several conserved residues of the H-N-H motif in the mechanism of DNA hydrolysis. We have used mutagenesis to test the involvement of these key residues in colicin toxicity, metal ion binding and catalysis. Our data show, for the first time, that the H-N-H motif is the site of DNA binding and that Mg2+-dependent cleavage of double-stranded DNA is responsible for bacterial cell death. We demonstrate that more active site residues are required for catalysis in the presence of Mg2+ ions than transition metals, consistent with the recent hypothesis that the E9 DNase hydrolyses DNA by two distinct, cation-dependent catalytic mechanisms. The roles of individual amino acids within the H-N-H motif are discussed in the context of the available structural information on this and related DNases and we address the possible mechanistic similarities between caspase-activated DNases, responsible for the degradation of chromatin in eukaryotic apoptosis, and H-N-H DNases. PMID:12136104

  8. 6. Building E9; view of glass lines for dilute liquor ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. Building E-9; view of glass lines for dilute liquor and spent acid; second floor, looking ESE. Bottom of wash tank is at the top of the view. (Ryan and Harms) - Holston Army Ammunition Plant, RDX-and-Composition-B Manufacturing Line 9, Kingsport, Sullivan County, TN

  9. Mechanism and cleavage specificity of the H-N-H endonuclease colicin E9.

    PubMed

    Pommer, A J; Cal, S; Keeble, A H; Walker, D; Evans, S J; Kühlmann, U C; Cooper, A; Connolly, B A; Hemmings, A M; Moore, G R; James, R; Kleanthous, C

    2001-12-01

    Colicin endonucleases and the H-N-H family of homing enzymes share a common active site structural motif that has similarities to the active sites of a variety of other nucleases such as the non-specific endonuclease from Serratia and the sequence-specific His-Cys box homing enzyme I-PpoI. In contrast to these latter enzymes, however, it remains unclear how H-N-H enzymes cleave nucleic acid substrates. Here, we show that the H-N-H enzyme from colicin E9 (the E9 DNase) shares many of the same basic enzymological characteristics as sequence-specific H-N-H enzymes including a dependence for high concentrations of Mg2+ or Ca2+ with double-stranded substrates, a high pH optimum (pH 8-9) and inhibition by monovalent cations. We also show that this seemingly non-specific enzyme preferentially nicks double-stranded DNA at thymine bases producing 3'-hydroxy and 5'-phosphate termini, and that the enzyme does not cleave small substrates, such as dinucleotides or nucleotide analogues, which has implications for its mode of inhibition in bacteria by immunity proteins. The E9 DNase will also bind single-stranded DNA above a certain length and in a sequence-independent manner, with transition metals such as Ni2+ optimal for cleavage but Mg2+ a poor cofactor. Ironically, the H-N-H motif of the E9 DNase although resembling the zinc binding site of a metalloenzyme does not support zinc-mediated hydrolysis of any DNA substrate. Finally, we demonstrate that the E9 DNase also degrades RNA in the absence of metal ions. In the context of current structural information, our data show that the H-N-H motif is an adaptable catalytic centre able to hydrolyse nucleic acid by different mechanisms depending on the substrate and metal ion regime.

  10. Measurement of total electron content of midlatitude ionosphere and protonosphere via Faraday rotation and group relay techniques using transmission from geostationary satellites ATS-3 and ATS-6

    NASA Technical Reports Server (NTRS)

    Paul, M. P.

    1982-01-01

    Measurement of integrated columnar electron content and total electron content for the local ionosphere and the overlying protonosphere via Faraday rotation and group delay techniques has proven very useful. A field station was established having the geographic location of 31.5 deg N latitude and 91.06 deg W longitude to accomplish these objectives. A polarimeter receiving system was set up in the beginning to measure the Faraday rotation of 137.35 MHz radio signal from geostationary satellite ATS 3 to yield the integrated columnar electron content of the local ionosphere. The measurement was continued regularly, and the analysis of the data thus collected provided a synopsis of the statistical variation of the ionosphere along with the transient variations that occurred during the periods of geomagnetic and other disturbances.

  11. Satellite Communication.

    ERIC Educational Resources Information Center

    Technology Teacher, 1985

    1985-01-01

    Presents a discussion of communication satellites: explains the principles of satellite communication, describes examples of how governments and industries are currently applying communication satellites, analyzes issues confronting satellite communication, links mathematics and science to the study of satellite communication, and applies…

  12. THE ZURICH ENVIRONMENTAL STUDY OF GALAXIES IN GROUPS ALONG THE COSMIC WEB. III. GALAXY PHOTOMETRIC MEASUREMENTS AND THE SPATIALLY RESOLVED COLOR PROPERTIES OF EARLY- AND LATE-TYPE SATELLITES IN DIVERSE ENVIRONMENTS

    SciTech Connect

    Cibinel, A.; Carollo, C. M.; Lilly, S. J.; Miniati, F.; Pipino, A.; Cameron, E.; Peng, Y.; Rudick, C. S.; Bonoli, S.; Silverman, J. D.; Van Gorkom, J. H.; Finoguenov, A.; Norberg, P. E-mail: marcella@phys.ethz.ch

    2013-11-10

    We present photometric measurements for the galaxies—and when possible their bulges and disks—in the 0.05 < z < 0.0585 groups of the Zurich Environmental Study (ZENS); these measurements include (B – I) colors, color gradients and maps, color dispersions, as well as stellar masses and star formation rates. The ZENS galaxies are classified into quenched, moderately star-forming, and strongly star-forming using a combination of spectral features and far-UV-to-optical colors; this approach optimally distinguishes quenched systems from dust-reddened star-forming galaxies. The latter contribute up to 50% to the (B – I) 'red sequence' at ∼10{sup 10} M{sub ☉}. At fixed morphological or spectral type, we find that galaxy stellar masses are largely independent of environment, and especially of halo mass. As a first utilization of our photometric database, we study, at fixed stellar mass and Hubble type, how (B – I) colors, color gradients, and color dispersion of disk satellites depend on group mass M{sub GROUP}, group-centric distance R/R{sub 200}, and large-scale structure overdensity δ{sub LSS}. The strongest environmental trend is found for disk-dominated satellites with M{sub GROUP} and R/R{sub 200}. At M ∼< 10{sup 10} M{sub ☉}, disk-dominated satellites are redder in the inner regions of the groups than in the outer parts. At M ∼> 10{sup 10} M{sub ☉}, these satellites have shallower color gradients in higher mass groups and in the cores of groups compared with lower mass groups and the outskirts of groups. Stellar population analyses and semi-analytic models suggest that disk-dominated satellites undergo quenching of star formation in their outer disks, on timescales τ{sub quench} ∼ 2 Gyr, as they progressively move inside the group potential.

  13. Communications technology satellite

    NASA Technical Reports Server (NTRS)

    1976-01-01

    A description of the Communications Technology Satellite (CTS), its planned orbit, its experiments, and associated ground facilities was given. The communication experiments, to be carried out by a variety of groups in both the United States and Canada, include tele-education, tele-medicine, community interaction, data communications and broadcasting. A historical summary of communications satellite development was also included.

  14. Improvement of spatial memory function in APPswe/PS1dE9 mice after chronic inhibition of phosphodiesterase type 4D.

    PubMed

    Sierksma, A S R; van den Hove, D L A; Pfau, F; Philippens, M; Bruno, O; Fedele, E; Ricciarelli, R; Steinbusch, H W M; Vanmierlo, T; Prickaerts, J

    2014-02-01

    Phosphodiesterase type 4 inhibitors (PDE4-Is) have received increasing attention as cognition-enhancers and putative treatment strategies for Alzheimer's disease (AD). By preventing cAMP breakdown, PDE4-Is can enhance intracellular signal transduction and increase the phosphorylation of cAMP response element-binding protein (CREB) and transcription of proteins related to synaptic plasticity and associated memory formation. Unfortunately, clinical development of PDE4-Is has been seriously hampered by emetic side effects. The new isoform-specific PDE4D-I, GEBR-7b, has shown to have beneficial effects on memory at non-emetic doses. The aim of the current study was to investigate chronic cognition-enhancing effects of GEBR-7b in a mouse model of AD. To this extent, 5-month-old (5M) APPswe/PS1dE9 mice received daily subcutaneous injections with GEBR-7b (0.001 mg/kg) or vehicle for a period of 3 weeks, and were tested on affective and cognitive behavior at 7M. We demonstrated a cognition-enhancing potential in APPswe/PS1dE9 mice as their spatial memory function at 7M in the object location test was improved by prior GEBR-7b treatment. APPswe/PS1dE9 mice displayed lower levels of CREB phosphorylation, which remained unaltered after chronic GEBR-7b treatment, and higher levels of tau in the hippocampus. Hippocampal brain-derived neurotrophic factor levels and synaptic densities were not different between experimental groups and no effects were observed on hippocampal GSK3β and tau phosphorylation or Aβ levels. In conclusion, GEBR-7b can enhance spatial memory function in the APPswe/PS1dE9 mouse model of AD. Although the underlying mechanisms of its cognition-enhancing potential remain to be elucidated, PDE4D inhibition appears an interesting novel therapeutic option for cognitive deficits in AD.

  15. Identification of putative active-site residues in the DNase domain of colicin E9 by random mutagenesis.

    PubMed

    Garinot-Schneider, C; Pommer, A J; Moore, G R; Kleanthous, C; James, R

    1996-08-01

    We have used random mutagenesis to identify putative active-site residues in the C-terminal cytotoxic endonuclease domain of the bacterial toxin colicin E9. Six single-site mutations in the DNase domain were isolated which destroyed the toxic action of the colicin. DNA sequencing identified the mutations as Gly460Asp, Arg544Gly, Glu548Gly, Thr571Ile, His575Tyr and His579Tyr. All six wild-type residues are highly conserved in the DNase domains of both the E group colicins and the closely related pyocins. Site-directed mutagenesis was then used to substitute the wild-type amino acid residue at each of these positions for an alanine residue in order to distinguish important from unimportant sites. Two of the six alanine-mutant colicins (Gly460Ala and His579Ala) exhibited significant in vivo activity, unlike the original mutation of these residues, and were therefore not characterised further. The Thr571Ala mutant colicin, although not inactive, was significantly less active than the control. The other three alanine mutants (Arg544Ala, Glu548Ala and His575Ala remained completely inactive in the in vivo tests. Each 15 kDa alanine-mutant DNase domain was overexpressed and purified using a tandem-expression strategy which relies on the enzyme being able to bind to the natural inhibitor, Im9. Tryptophan emission spectra of the alanine mutants showed significant alterations in the emission maxima of all but the His575Ala mutant, suggesting changes in the tertiary structure of these mutant proteins. Activity measurements, using the spectrophotometric Kunitz assay, indicated that the Thr571Ala mutant was partially active as an endonuclease but the remaining alanine mutants were all completely inactive. All four mutant proteins, however, retained their ability to bind DNA in a gel shift assay, suggesting the mutations affect catalytic rather than substrate-binding residues. Searching the sequence databases for possible homology to other DNA-binding proteins revealed a

  16. Repeatability and Reproducibility of Compression Strength Measurements Conducted According to ASTM E9

    NASA Technical Reports Server (NTRS)

    Luecke, William E.; Ma, Li; Graham, Stephen M.; Adler, Matthew A.

    2010-01-01

    Ten commercial laboratories participated in an interlaboratory study to establish the repeatability and reproducibility of compression strength tests conducted according to ASTM International Standard Test Method E9. The test employed a cylindrical aluminum AA2024-T351 test specimen. Participants measured elastic modulus and 0.2 % offset yield strength, YS(0.2 % offset), using an extensometer attached to the specimen. The repeatability and reproducibility of the yield strength measurement, expressed as coefficient of variations were cv(sub r)= 0.011 and cv(sub R)= 0.020 The reproducibility of the test across the laboratories was among the best that has been reported for uniaxial tests. The reported data indicated that using diametrically opposed extensometers, instead of a single extensometer doubled the precision of the test method. Laboratories that did not lubricate the ends of the specimen measured yield stresses and elastic moduli that were smaller than those measured in laboratories that lubricated the specimen ends. A finite element analysis of the test specimen deformation for frictionless and perfect friction could not explain the discrepancy, however. The modulus measured from stress-strain data were reanalyzed using a technique that finds the optimal fit range, and applies several quality checks to the data. The error in modulus measurements from stress-strain curves generally increased as the fit range decreased to less than 40 % of the stress range.

  17. Satellite RNAs and Satellite Viruses.

    PubMed

    Palukaitis, Peter

    2016-03-01

    Satellite RNAs and satellite viruses are extraviral components that can affect either the pathogenicity, the accumulation, or both of their associated viruses while themselves being dependent on the associated viruses as helper viruses for their infection. Most of these satellite RNAs are noncoding RNAs, and in many cases, have been shown to alter the interaction of their helper viruses with their hosts. In only a few cases have the functions of these satellite RNAs in such interactions been studied in detail. In particular, work on the satellite RNAs of Cucumber mosaic virus and Turnip crinkle virus have provided novel insights into RNAs functioning as noncoding RNAs. These effects are described and potential roles for satellite RNAs in the processes involved in symptom intensification or attenuation are discussed. In most cases, models describing these roles involve some aspect of RNA silencing or its suppression, either directly or indirectly involving the particular satellite RNA.

  18. Novel behavioural characteristics of female APPSwe/PS1ΔE9 double transgenic mice.

    PubMed

    Cheng, David; Low, Jac Kee; Logge, Warren; Garner, Brett; Karl, Tim

    2014-03-01

    Murine models are commonly used to evaluate progression of Alzheimer's disease. APPSwe/PS1ΔE9 (APPxPS1) mice have previously been reported to demonstrate impaired learning and memory in the Morris water maze test. However, this paradigm introduces a variety of behaviours that may confound performance of the mice, thus an alternative was sought. A battery of behavioural tests (light-dark test, elevated plus maze, novel object recognition task, social recognition test, cheeseboard task and prepulse inhibition) was used to investigate various behavioural and cognitive domains with relevance to Alzheimer's disease. We found 9-month old female APPxPS1 mice exhibited impaired spatial memory in the reversal cheeseboard task. In addition, task-dependent hyperlocomotion and anxiolytic-like behaviours were observed in the light-dark test. Female APPxPS1 demonstrated intact object recognition memory and sensorimotor gating was not significantly decreased compared to control mice except for one particular interstimulus interval. The social recognition test failed to detect preference for social novelty in control females. In conclusion, this is the first study to describe a memory deficit in female APPxPS1 mice in the hidden cheeseboard task. Transgenic females also exhibited task-dependent reduction in anxiety behaviours and hyperlocomotion. These novel findings enhance our understanding of the behavioural phenotype of APPxPS1 females and present the cheeseboard as a valid alternative to other established spatial memory tests. Furthermore, the task-dependency of some of our findings suggests that behavioural profiling of APPxPS1 transgenic mice should be assessed using a variety of behavioural paradigms.

  19. Meteorological satellites

    NASA Technical Reports Server (NTRS)

    Allison, L. J. (Editor); Schnapf, A.; Diesen, B. C., III; Martin, P. S.; Schwalb, A.; Bandeen, W. R.

    1980-01-01

    An overview is presented of the meteorological satellite programs that have been evolving from 1958 to the present, and plans for the future meteorological and environmental satellite systems that are scheduled to be placed into service in the early 1980's are reviewed. The development of the TIROS family of weather satellites, including TIROS, ESSA, ITOS/NOAA, and the present TIROS-N (the third generation operational system) is summarized. The contribution of the Nimbus and ATS technology satellites to the development of the operational-orbiting and geostationary satellites is discussed. Included are descriptions of both the TIROS-N and the DMSP payloads currently under development to assure a continued and orderly growth of these systems into the 1980's.

  20. Report of the Terrestrial Bodies Science Working Group. Volume 1: Executive summary. [Terrestrial planets, Galilean satellites, Comets, Asteroids, and the Moon

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Current knowledge of Mercury, Venus, Mars, the Moon, asteroids, comets, and the Galilean satellites were reviewed along with related NASA programs and available mission concepts. Exploration plans for the 1980 to 1990 period are outlined and recommendations made. Topics discussed include: scientific objectives and goals, exploration strategy and recommended mission plans, supporting research and technology, Earth-based and Earth-orbital investigations, data analysis and synthesis, analysis of extraterrestrial materials, broadening the science support base, and international cooperation.

  1. Tandem overproduction and characterisation of the nuclease domain of colicin E9 and its cognate inhibitor protein Im9.

    PubMed

    Wallis, R; Reilly, A; Barnes, K; Abell, C; Campbell, D G; Moore, G R; James, R; Kleanthous, C

    1994-03-01

    We report the overproduction of the non-specific endonuclease domain of the bacterial toxin colicin E9 and its preliminary characterisation in vitro. The enzymatic colicins (61 kDa) are normally released from producing cells in a complex with their cognate inhibitors, known as the immunity proteins (9.5 kDa). Tryptic digestion of the purified ColE9 complex was found to generate two major components, a monomer derived from the N-terminal and central regions of the toxin and a heterodimer comprising the catalytically active C-terminal domain of the colicin bound to its intact immunity protein, Im9. N-terminal amino acid sequencing, in conjunction with electrospray mass spectrometry, shows that preparations of the DNase domain isolated by this method are heterogeneous, thus making subsequent mechanistic and structural analysis difficult. This problem was circumvented by selectively overexpressing the C-terminal 15-kDa nuclease domain of colicin E9 in tandem with its cognate inhibitor in Escherichia coli. This tandem overexpression strategy allowed high-level production of a 25-kDa protein complex comprising the C-terminal DNase domain of colicin E9 tightly bound to its specific inhibitor Im9, thus masking the anticipated toxicity of the nuclease. The DNase domain was then separated from Im9 under denaturing conditions, refolded by removal of the denaturant and the renatured protein shown to possess both endonuclease and Im9 binding activity. These results describe a novel method for the overproduction of a nuclease in bacteria by co-expressing its specific inhibitor and lay the foundations for a full mechanistic, biophysical and structural characterization of the isolated DNase domain of the colicin E9 toxin. PMID:8125102

  2. Satellite myths

    NASA Astrophysics Data System (ADS)

    Easton, Roger L.; Hall, David

    2008-01-01

    Richard Corfield's article “Sputnik's legacy” (October 2007 pp23-27) states that the satellite on board the US Vanguard rocket, which exploded during launch on 6 December 1957 two months after Sputnik's successful take-off, was “a hastily put together contraption of wires and circuitry designed only to send a radio signal back to Earth”. In fact, the Vanguard satellite was developed over a period of several years and put together carefully using the best techniques and equipment available at the time - such as transistors from Bell Laboratories/Western Electric. The satellite contained not one but two transmitters, in which the crystal-controlled oscillators had been designed to measure both the temperature of the satellite shell and of the internal package.

  3. Satellite Videoconferences

    NASA Technical Reports Server (NTRS)

    1990-01-01

    NASA is helping thousands of teachers to learn more about aerospace matters, improve their classroom skills, and expand significantly the content of their aerospace education curricula by means of live educational satellite videoconferences. The 1 1/2 hour 'Update for Teachers' programs originate at Oklahoma State University (OSU) Telecommunications Center. The television signals are transmitted to the WESTAR IV communications satellite, which remits them to participating schools across the U.S. and in parts of Mexico and Canada. The schools are equipped with small home style satellite reception dishes. Education Satellite Videoconference programs are conducted four times yearly, covering a variety of aerospace subjects. Teachers can call toll-free and have questions answered after the speaker's presentations. Information about NASA educational resources and how to obtain them will be provided.

  4. Satellite positioning

    NASA Technical Reports Server (NTRS)

    Colombo, Oscar L.; Watkins, Michael M.

    1991-01-01

    Developments in satellite positioning techniques and their applications are reviewed on the basis of the theoretical and practical work published by U.S. researchers in 1987-1990. Current techniques are classified into two main categories: satellite laser tracking and radio tracking. Particular attention is given to the Geoscience Laser Ranging System, the Lunar Laser Ranging concept; GPS ephemerides determination, fiducial networks, and reference frame; static GPS positioning; and kinematic GPS positioning.

  5. THE ONE ROOM SATELLITE.

    ERIC Educational Resources Information Center

    DREYFUS, LEE S.

    A WISCONSIN HIGH SCHOOL FRENCH CLASS AND A GROUP OF STUDENTS IN AN ENGLISH CALSS AT THE LYCEE HENRI IV OF PARIS, FRANCE, PARTICIPATED IN A COMBINED CLASS SESSION IN THE FIRST INTERNATIONAL TV CLASSROOM EXCHANGE. THE TV SIGNALS WERE EXCHANGED BY MEANS OF THE EARLY BIRD SATELLITE AND PERMITTED THE STUDENTS TO EXCHANGE MESSAGES. DURING THE TELECAST…

  6. Synthesis and characterization of PbS nanocrystals in water/C12E9/cyclohexane microemulsions

    NASA Astrophysics Data System (ADS)

    Zhang, Bo; Li, Guanghai; Zhang, Jun; Zhang, Yong; Zhang, Lide

    2003-04-01

    PbS nanocrystals were prepared using water/C12E9/cyclohexane microemulsions as nanoreactors. The sizes and morphologies of the cubic PbS nanocrystals can be modified by controlling the concentration of ions, the volume ratio of water to surfactant and the reaction temperature. The shuttle-like nanoparticles consisting of PbS nanocrystals were obtained by reaction at the temperature of 150°C.

  7. Small satellites

    NASA Technical Reports Server (NTRS)

    Thomas, P.; Veverka, J.; Dermott, S.

    1986-01-01

    Satellites smaller than Mimas (r = 195 km) are distinguished by irregular overall shapes and by rough limb topography. Material properties and impact cratering dominate the shaping of these objects. Long fragmentation histories can produce a variety of internal structures, but so far there is no direct evidence that any small satellite is an equilibrium ellipsoid made up of noncohesive gravitationally bound rubble. One many bodies that orbit close to their primary the tidal and rotational components of surface gravity strongly affect the directions of local g and thereby affect the redistribution of regolith by mass wasting. Downslope movement of regolith is extensive on Deimos, and is probably effective on many other small satellites. It is shown that in some cases observed patterns of downslope mass wasting cold produce useful constraints on the satellite's mean density. The diversity of features seen in the few high-resolution images of small satellites currently available suggests that these objects have undergone complex histories of cratering, fragmentation, and regolith evolution.

  8. Satellite Communications for ATM

    NASA Technical Reports Server (NTRS)

    Shamma, Mohammed A.

    2003-01-01

    This presentation is an overview on Satellite Communication for the Aeronautical Telecommunication Management (ATM) research. Satellite Communications are being considered by the FAA and NASA as a possible alternative to the present and future ground systems supporting Air Traffic Communications. The international Civil Aviation Organization (ICAO) have in place Standards and Recommended Practices (SARPS) for the Aeronautical Mobile Satellite Services (AMSS) which is mainly derived from the pre-existing Inmarsat service that has been in service since the 1980s. The Working Group A of the Aeronautical Mobile Communication Panel of ICAO has also been investigating SARPS for what is called the Next Generation Satellite Service (NGSS) which conforms less to the Inmarsat based architecture and explores wider options in terms of satellite architectures. Several designs are being proposed by Firms such as Boeing, ESA, NASA that are geared toward full or secondary usage of satellite communications for ATM. Satellite communications for ATM can serve several purposes ranging from primary usage where ground services would play a minimal backup role, to an integrated solution where it will be used to cover services, or areas that are less likely to be supported by the proposed and existing ground infrastructure. Such Integrated roles can include usage of satellite communications for oceanic and remote land areas for example. It also can include relieving the capacity of the ground network by providing broadcast based services of Traffic Information Services messages (TIS-B), or Flight Information Services (FIS-B) which can take a significant portion of the ground system capacity. Additionally, satellite communication can play a backup role to support any needs for ground replacement, or additional needed capacity even after the new digital systems are in place. The additional bandwidth that can be provided via satellite communications can also open the door for many new

  9. Workshop on Satellite Meteorology. Part 1; Satellite and Their Data

    NASA Technical Reports Server (NTRS)

    1982-01-01

    The Workshop on Satellite Meteorology is co-sponsored by the Cooperative Institute for Research in the Atmosphere (CIRA) at Colorado State University and the American Meteorlogical Society's Committee on Meteorological Aspects of Aerospace Systems. The workshop covers uses of satellite data in atmospheric science. It provides state-of-the-art information to those in Universities, research groups, and other users. One area of primary focus is to provide source material to university personnel for developing and augmenting courses in satellite meteorology and the atmospheric sciences. The items in the program include information on meteorological satellites and data sources, uses of satellite imagery for all scales of weather analysis and forecasting, uses of sounding data and other radiance information and research opportunities on interactive systems. Each session is presented by a group of experts in the field and includes an open discussion of the state-of-the-art and promising areas for future development. This pre-print volume is one of three parts on the workshop. The three parts are: PART I. Satellites and Their Data; PART II. Satellite Image Analysis and Interpretation; PART III. Satellite Soundings and Their Uses.

  10. MO-E-9A-01: Risk Based Quality Management: TG100 In Action

    SciTech Connect

    Huq, M; Palta, J; Dunscombe, P; Thomadsen, B

    2014-06-15

    One of the goals of quality management in radiation therapy is to gain high confidence that patients will receive the prescribed treatment correctly. To accomplish these goals professional societies such as the American Association of Physicists in Medicine (AAPM) has published many quality assurance (QA), quality control (QC), and quality management (QM) guidance documents. In general, the recommendations provided in these documents have emphasized on performing device-specific QA at the expense of process flow and protection of the patient against catastrophic errors. Analyses of radiation therapy incidents find that they are most often caused by flaws in the overall therapy process, from initial consult through final treatment, than by isolated hardware or computer failures detectable by traditional physics QA. This challenge is shared by many intrinsically hazardous industries. Risk assessment tools and analysis techniques have been developed to define, identify, and eliminate known and/or potential failures, problems, or errors, from a system, process and/or service before they reach the customer. These include, but are not limited to, process mapping, failure modes and effects analysis (FMEA), fault tree analysis (FTA), and establishment of a quality management program that best avoids the faults and risks that have been identified in the overall process. These tools can be easily adapted to radiation therapy practices because of their simplicity and effectiveness to provide efficient ways to enhance the safety and quality of treatment processes. Task group 100 (TG100) of AAPM has developed a risk-based quality management program that uses these tools. This session will be devoted to a discussion of these tools and how these tools can be used in a given radiotherapy clinic to develop a risk based QM program. Learning Objectives: Learn how to design a process map for a radiotherapy process. Learn how to perform a FMEA analysis for a given process. Learn what

  11. Managing Satellites

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Integral Systems, Inc.'s EPOCH 2000 forms the core of NASA's Near Earth Asteroid Rendezvous (NEAR) mission's command and control center. EPOCH 2000, which allows ground operators to monitor and control satellites over a wide area network, owes part of its heritage from work completed to support Goddard Space Flight Center. The software automates telemetry processing, commanding, anomaly detection, and archiving collected data. The NEAR spacecraft, launched in February 1996, will rendezvous in early 1999 and orbit the Asteroid Eros for a year. Integral Systems also provided Low Earth Orbit Autonomous Ground Terminals (LEO-Ts) to NASA. The LEO-T is designed to make it easier and less expensive for principal investigators to obtain telemetry, tracking and control services for their science missions. The company products have supported well over 70 satellite missions aimed at scientific research, meteorology, or communications applications.

  12. Virtual Satellite

    NASA Technical Reports Server (NTRS)

    Hammrs, Stephan R.

    2008-01-01

    Virtual Satellite (VirtualSat) is a computer program that creates an environment that facilitates the development, verification, and validation of flight software for a single spacecraft or for multiple spacecraft flying in formation. In this environment, enhanced functionality and autonomy of navigation, guidance, and control systems of a spacecraft are provided by a virtual satellite that is, a computational model that simulates the dynamic behavior of the spacecraft. Within this environment, it is possible to execute any associated software, the development of which could benefit from knowledge of, and possible interaction (typically, exchange of data) with, the virtual satellite. Examples of associated software include programs for simulating spacecraft power and thermal- management systems. This environment is independent of the flight hardware that will eventually host the flight software, making it possible to develop the software simultaneously with, or even before, the hardware is delivered. Optionally, by use of interfaces included in VirtualSat, hardware can be used instead of simulated. The flight software, coded in the C or C++ programming language, is compilable and loadable into VirtualSat without any special modifications. Thus, VirtualSat can serve as a relatively inexpensive software test-bed for development test, integration, and post-launch maintenance of spacecraft flight software.

  13. DHA diet reduces AD pathology in young APPswe/PS1 Delta E9 transgenic mice: possible gender effects.

    PubMed

    Perez, Sylvia E; Berg, Brian M; Moore, Kenneth A; He, Bin; Counts, Scott E; Fritz, Jason J; Hu, Yuan-Shih; Lazarov, Orly; Lah, James J; Mufson, Elliott J

    2010-04-01

    Epidemiological and clinical trial findings suggest that consumption of docosahexaenoic acid (DHA) lowers the risk of Alzheimer's disease (AD). We examined the effects of short-term (3 months) DHA enriched diet on plaque deposition and synaptic defects in forebrain of young APPswe/PS1 Delta E9 transgenic (tg) and non-transgenic (ntg) mice. Gas chromatography revealed a significant increase in DHA concomitant with a decrease of arachidonic acid in both brain and liver in mice fed with DHA. Female tg mice consumed relatively more food daily than ntg female mice, independent of diet. Plaque load was significantly reduced in the cortex, ventral hippocampus and striatum of female APPswe/PS1 Delta E9 tg mice on DHA diet compared to female tg mice on control diet. Immunoblot quantitation of the APOE receptor, LR11, which is involved in APP trafficking and A beta production, were unchanged in mice on DHA or control diets. Moreover drebrin levels were significantly increased in the hippocampus of tg mice on the DHA diet. Finally, in vitro DHA treatment prevented amyloid toxicity in cell cultures. Our findings support the concept that increased DHA consumption may play and important role in reducing brain insults in female AD patients. PMID:19859965

  14. Identification of critical residues in the colicin E9 DNase binding region of the Im9 protein.

    PubMed Central

    Osborne, M J; Wallis, R; Leung, K Y; Williams, G; Lian, L Y; James, R; Kleanthous, C; Moore, G R

    1997-01-01

    1H-15N NMR studies, in conjunction with mutagenesis experiments, have been used to delineate the DNase-binding surface of the colicin E9 inhibitor protein Im9 (where Im stands for immunity protein). Complexes were formed between the 15 kDa unlabelled E9 DNase domain and the 9.5 kDa Im9 protein uniformly labelled with 15N. Approx. 90% of the amide resonances of the bound Im9 were assigned and spectral parameters obtained from 1H-15N heteronuclear single quantum coherence (HSQC) spectra were compared with those for the free Im9 assigned previously. Many of the amide resonances were shifted on complex formation, some by more than 2 p.p.m. in the 15N dimension and more than 0.5 p.p.m. in the 1H dimension. Most of the strongly shifted amides are located on the surfaces of two of the four helices, helix II and helix III. Whereas helix II had already been identified through genetic and biochemical investigations as an important determinant of biological specificity, helix III had not previously been implicated in binding to the DNase. To test the robustness of the NMR-delineated DNase-binding site, a selection of Im9 alanine mutants were constructed and their dissociation rate constants from E9 DNase-immunity protein complexes quantified by radioactive subunit exchange kinetics. Their off-rates correlated well with the NMR perturbation analysis; for example, residues that were highly perturbed in HSQC experiments, such as residues 34 (helix II) and 54 (helix III), had a marked effect on the DNase-immunity protein dissociation rate when replaced by alanine. The NMR and mutagenesis data are consistent with a DNase-binding region on Im9 composed of invariant residues in helix III and variable residues in helix II. The relationship of this binding site model to the wide range of affinities (Kd values in the range 10(-4) to 10(-16)M) that have been measured for cognate and non-cognate colicin DNase-immunity protein interactions is discussed. PMID:9169618

  15. Meteorological satellites

    NASA Astrophysics Data System (ADS)

    1981-10-01

    Meteor-2 (second generation meteorological satellite) and an experimental satellite on which instruments are being tested and modified for the requirements of hydrometeorology and a determination of natural resources are presently operational in the U.S.S.R. Television devices with a 1-10 km terrain image resolution operating in the visible and infrared region are used to determine the space system, velocity and direction of cloud movements and provide information about the snow and ice cover, cyclones, storms, vortices in the atmosphere, and velocity and direction of wind. Images with a 50-1000 m resolution make possible geological and hydrological surveys, an evaluation of the state of vegetation and crops, detection of forest fires, determination of pollution of the atmosphere and sea and determination of optimal fishing regions in the ocean. Measurement of the intensity of atmospheric radiation in narrow infrared regions and very high frequencies allows remote evaluation of the temperature and humidity distribution in the vertical cross section of the Earth's atmosphere.

  16. Outer planet satellites

    NASA Astrophysics Data System (ADS)

    Schenk, Paul M.

    Recent findings on the outer-planet satellites are presented, with special consideration given to data on the rheologic properties of ice on icy satellites, the satellite surfaces and exogenic processes, cratering on dead cratered satellites, volcanism, and the interiors of outer-planet satellites. Particular attention is given to the state of Titan's surface and the properties of Triton, Pluto, and Charon.

  17. Satellite altimetry

    NASA Technical Reports Server (NTRS)

    Cheney, Robert E.

    1992-01-01

    Since altimetry data are not really old enough to use the term data archaeology, Mr. Cheney referred to the stewardship of these data. He noted that it is very important to document the basis for an altimetry data set as the algorithms and corrections used to arrive at the Geophysical Data Record (GDR) have been improving and are continuing to improve the precision of sea level data derived from altimetry. He noted that the GEOSAT Exact Repeat Mission (ERM) data set has recently been reprocessed by his organization in the National Ocean Service of NOAA and made available to the scientific community on CD/ROM disks by the National Oceanographic Data Center of the U.S. (NODC). The new data set contains a satellite orbit more precise by an order of magnitude together with an improved water vapor correction. A new, comprehensive GDR Handbook has also been prepared.

  18. Satellites in Education.

    ERIC Educational Resources Information Center

    Jones, David

    1988-01-01

    Describes the methods and materials used to obtain satellite pictures from weather satellites. Discusses possible physics lessons which can be done using this equipment including orbital mechanics, and how the satellite works. (CW)

  19. The impact of Bdnf gene deficiency to the memory impairment and brain pathology of APPswe/PS1dE9 mouse model of Alzheimer's disease.

    PubMed

    Rantamäki, Tomi; Kemppainen, Susanna; Autio, Henri; Stavén, Saara; Koivisto, Hennariikka; Kojima, Masami; Antila, Hanna; Miettinen, Pasi O; Kärkkäinen, Elisa; Karpova, Nina; Vesa, Liisa; Lindemann, Lothar; Hoener, Marius C; Tanila, Heikki; Castrén, Eero

    2013-01-01

    Brain-derived neurotrophic factor (BDNF) importantly regulates learning and memory and supports the survival of injured neurons. Reduced BDNF levels have been detected in the brains of Alzheimer's disease (AD) patients but the exact role of BDNF in the pathophysiology of the disorder remains obscure. We have recently shown that reduced signaling of BDNF receptor TrkB aggravates memory impairment in APPswe/PS1dE9 (APdE9) mice, a model of AD. The present study examined the influence of Bdnf gene deficiency (heterozygous knockout) on spatial learning, spontaneous exploratory activity and motor coordination/balance in middle-aged male and female APdE9 mice. We also studied brain BDNF protein levels in APdE9 mice in different ages showing progressive amyloid pathology. Both APdE9 and Bdnf mutations impaired spatial learning in males and showed a similar trend in females. Importantly, the effect was additive, so that double mutant mice performed the worst. However, APdE9 and Bdnf mutations influenced spontaneous locomotion in contrasting ways, such that locomotor hyperactivity observed in APdE9 mice was normalized by Bdnf deficiency. Obesity associated with Bdnf deficiency did not account for the reduced hyperactivity in double mutant mice. Bdnf deficiency did not alter amyloid plaque formation in APdE9 mice. Before plaque formation (3 months), BDNF protein levels where either reduced (female) or unaltered (male) in the APdE9 mouse cortex. Unexpectedly, this was followed by an age-dependent increase in mature BDNF protein. Bdnf mRNA and phospho-TrkB levels remained unaltered in the cortical tissue samples of middle-aged APdE9 mice. Immunohistological studies revealed increased BDNF immunoreactivity around amyloid plaques indicating that the plaques may sequester BDNF protein and prevent it from activating TrkB. If similar BDNF accumulation happens in human AD brains, it would suggest that functional BDNF levels in the AD brains are even lower than reported, which could

  20. 13C metabolic flux analysis shows that resistin impairs the metabolic response to insulin in L6E9 myotubes

    PubMed Central

    2014-01-01

    Background It has been suggested that the adipokine resistin links obesity and insulin resistance, although how resistin acts on muscle metabolism is controversial. We aimed to quantitatively analyse the effects of resistin on the glucose metabolic flux profile and on insulin response in L6E9 myotubes at the metabolic level using a tracer-based metabolomic approach and our in-house developed software, Isodyn. Results Resistin significantly increased glucose uptake and glycolysis, altering pyruvate utilisation by the cell. In the presence of resistin, insulin only slightly increased glucose uptake and glycolysis, and did not alter the flux profile around pyruvate induced by resistin. Resistin prevented the increase in gene expression in pyruvate dehydrogenase-E1 and the sharp decrease in gene expression in cytosolic phosphoenolpyruvate carboxykinase-1 induced by insulin. Conclusions These data suggest that resistin impairs the metabolic activation of insulin. This impairment cannot be explained by the activity of a single enzyme, but instead due to reorganisation of the whole metabolic flux distribution. PMID:25217974

  1. NMR study of Ni2+ binding to the H-N-H endonuclease domain of colicin E9.

    PubMed Central

    Hannan, J. P.; Whittaker, S. B.; Davy, S. L.; Kühlmann, U. C.; Pommer, A. J.; Hemmings, A. M.; James, R.; Kleanthous, C.; Moore, G. R.

    1999-01-01

    Ni2+ affinity columns are widely used for protein purification, but they carry the risk that Ni2+ ions may bind to the protein, either adventitiously or at a physiologically important site. Dialysis against ethylenediaminetetraacetic acid (EDTA) is normally used to remove metal ions bound adventitiously to proteins; however, this approach does not always work. Here we report that a bacterial endonuclease, the DNase domain of colicin E9, binds Ni2+ acquired from Ni2+ affinity columns, and appears to bind [Ni(EDTA)(H2O)n]2- at low ionic strength. NMR was used to detect the presence of both Ni2+ coordinated to amino acid side chains and [Ni(EDTA)(H2O)N]2-. Dialysis against > or =0.2 M NaCl was required to remove the [Ni(EDTA)(H2O)n]2-. The NMR procedure we have used to characterize the presence of Ni2+ and [Ni(EDTA)(H2O)n]2- should be applicable to other proteins where there is the possibility of binding paramagnetic metal ions that are present to expedite protein purification. In the present case, the binding of Ni2+ seems likely to be physiologically relevant, and the NMR data complement recent X-ray crystallographic evidence concerning the number of histidine ligands to bound Ni2+. PMID:10452617

  2. Probing metal ion binding and conformational properties of the colicin E9 endonuclease by electrospray ionization time-of-flight mass spectrometry

    PubMed Central

    van den Bremer, Ewald T.J.; Jiskoot, Wim; James, Richard; Moore, Geoffrey R.; Kleanthous, Colin; Heck, Albert J.R.; Maier, Claudia S.

    2002-01-01

    Nano-electrospray ionization time-of-flight mass spectrometry (ESI-MS) was used to study the conformational consequences of metal ion binding to the colicin E9 endonuclease (E9 DNase) by taking advantage of the unique capability of ESI-MS to allow simultaneous assessment of conformational heterogeneity and metal ion binding. Alterations of charge state distributions on metal ion binding/release were correlated with spectral changes observed in far- and near-UV circular dichroism (CD) and intrinsic tryptophan fluorescence. In addition, hydrogen/deuterium (H/D) exchange experiments were used to probe structural integrity. The present study shows that ESI-MS is sensitive to changes of the thermodynamic stability of E9 DNase as a result of metal ion binding/release in a manner consistent with that deduced from proteolysis and calorimetric experiments. Interestingly, acid-induced release of the metal ion from the E9 DNase causes dramatic conformational instability associated with a loss of fixed tertiary structure, but secondary structure is retained. Furthermore, ESI-MS enabled the direct observation of the noncovalent protein complex of E9 DNase bound to its cognate immunity protein Im9 in the presence and absence of Zn2+. Gas-phase dissociation experiments of the deuterium-labeled binary and ternary complexes revealed that metal ion binding, not Im9, results in a dramatic exchange protection of E9 DNase in the complex. In addition, our metal ion binding studies and gas-phase dissociation experiments of the ternary E9 DNase-Zn2+-Im9 complex have provided further evidence that electrostatic interactions govern the gas phase ion stability. PMID:12070327

  3. Galaxy groups

    SciTech Connect

    Brent Tully, R.

    2015-02-01

    Galaxy groups can be characterized by the radius of decoupling from cosmic expansion, the radius of the caustic of second turnaround, and the velocity dispersion of galaxies within this latter radius. These parameters can be a challenge to measure, especially for small groups with few members. In this study, results are gathered pertaining to particularly well-studied groups over four decades in group mass. Scaling relations anticipated from theory are demonstrated and coefficients of the relationships are specified. There is an update of the relationship between light and mass for groups, confirming that groups with mass of a few times 10{sup 12}M{sub ⊙} are the most lit up while groups with more and less mass are darker. It is demonstrated that there is an interesting one-to-one correlation between the number of dwarf satellites in a group and the group mass. There is the suggestion that small variations in the slope of the luminosity function in groups are caused by the degree of depletion of intermediate luminosity systems rather than variations in the number per unit mass of dwarfs. Finally, returning to the characteristic radii of groups, the ratio of first to second turnaround depends on the dark matter and dark energy content of the universe and a crude estimate can be made from the current observations of Ω{sub matter}∼0.15 in a flat topology, with a 68% probability of being less than 0.44.

  4. Satellite Data Simulator Unit: A Multisensor, Multispectral Satellite Simulator Package

    NASA Technical Reports Server (NTRS)

    Masunaga, Hirohiko; Matsui, Toshihisa; Tao, Wei-Kuo; Hou, Arthur Y.; Kummerow, Christian D.; Nakajima, Teruyuki; Bauer, Peter; Olson, William S.; Sekiguchi, Miho; Nakajima, Teruyuki

    2010-01-01

    Several multisensor simulator packages are being developed by different research groups across the world. Such simulator packages [e.g., COSP , CRTM, ECSIM, RTTO, ISSARS (under development), and SDSU (this article), among others] share overall aims, although some are targeted more on particular satellite programs or specific applications (for research purposes or for operational use) than others. The SDSU or Satellite Data Simulator Unit is a general-purpose simulator composed of Fortran 90 codes and applicable to spaceborne microwave radiometer, radar, and visible/infrared imagers including, but not limited to, the sensors listed in a table. That shows satellite programs particularly suitable for multisensor data analysis: some are single satellite missions carrying two or more instruments, while others are constellations of satellites flying in formation. The TRMM and A-Train are ongoing satellite missions carrying diverse sensors that observe clouds and precipitation, and will be continued or augmented within the decade to come by future multisensor missions such as the GPM and Earth-CARE. The ultimate goals of these present and proposed satellite programs are not restricted to clouds and precipitation but are to better understand their interactions with atmospheric dynamics/chemistry and feedback to climate. The SDSU's applicability is not technically limited to hydrometeor measurements either, but may be extended to air temperature and humidity observations by tuning the SDSU to sounding channels. As such, the SDSU and other multisensor simulators would potentially contribute to a broad area of climate and atmospheric sciences. The SDSU is not optimized to any particular orbital geometry of satellites. The SDSU is applicable not only to low-Earth orbiting platforms as listed in Table 1, but also to geostationary meteorological satellites. Although no geosynchronous satellite carries microwave instruments at present or in the near future, the SDSU would be

  5. Iodine Satellite

    NASA Technical Reports Server (NTRS)

    Kamhawi, Hani; Dankanich, John; Martinez, Andres; Petro, Andrew

    2015-01-01

    The Iodine Satellite (iSat) spacecraft will be the first CubeSat to demonstrate high change in velocity from a primary propulsion system by using Hall thruster technology and iodine as a propellant. The mission will demonstrate CubeSat maneuverability, including plane change, altitude change and change in its closest approach to Earth to ensure atmospheric reentry in less than 90 days. The mission is planned for launch in fall 2017. Hall thruster technology is a type of electric propulsion. Electric propulsion uses electricity, typically from solar panels, to accelerate the propellant. Electric propulsion can accelerate propellant to 10 times higher velocities than traditional chemical propulsion systems, which significantly increases fuel efficiency. To enable the success of the propulsion subsystem, iSat will also demonstrate power management and thermal control capabilities well beyond the current state-of-the-art for spacecraft of its size. This technology is a viable primary propulsion system that can be used on small satellites ranging from about 22 pounds (10 kilograms) to more than 1,000 pounds (450 kilograms). iSat's fuel efficiency is ten times greater and its propulsion per volume is 100 times greater than current cold-gas systems and three times better than the same system operating on xenon. iSat's iodine propulsion system consists of a 200 watt (W) Hall thruster, a cathode, a tank to store solid iodine, a power processing unit (PPU) and the feed system to supply the iodine. This propulsion system is based on a 200 W Hall thruster developed by Busek Co. Inc., which was previously flown using xenon as the propellant. Several improvements have been made to the original system to include a compact PPU, targeting greater than 80 percent reduction in mass and volume of conventional PPU designs. The cathode technology is planned to enable heaterless cathode conditioning, significantly increasing total system efficiency. The feed system has been designed to

  6. Navy satellite communications

    NASA Astrophysics Data System (ADS)

    Clair, William C.

    1992-03-01

    The history, current status, and future plans of Navy satellite communications are reviewed. Particular attention is given to Fleet Satellites; the Defense Satellite Communications System; the International Maritime Satellite; Core Command and Control (Core C2), General Purpose Communications, and Navy EHF SATCOM program; and the Copernicus architecture.

  7. Tethered Communication Satellites

    NASA Technical Reports Server (NTRS)

    Von Tiesenhausen, G.

    1986-01-01

    Report describes concept for placing several communication satellites in geostationary orbit without taking up more space than assigned to single satellite. Proposed scheme eases orbital crowding more economically than space platforms. Concept requires minimal redesign of existing satellites and accommodates many satellites in just one orbital slot. System much lighter in weight than geostationary platform and easier and more economical to transport.

  8. Outer planet satellites

    SciTech Connect

    Schenk, P.M. )

    1991-01-01

    Recent findings on the outer-planet satellites are presented, with special consideration given to data on the rheologic properties of ice on icy satellites, the satellite surfaces and exogenic processes, cratering on dead cratered satellites, volcanism, and the interiors of outer-planet satellites. Particular attention is given to the state of Titan's surface and the properties of Triton, Pluto, and Charon. 210 refs.

  9. Vitamin D2-enriched button mushroom (Agaricus bisporus) improves memory in both wild type and APPswe/PS1dE9 transgenic mice.

    PubMed

    Bennett, Louise; Kersaitis, Cindy; Macaulay, Stuart Lance; Münch, Gerald; Niedermayer, Garry; Nigro, Julie; Payne, Matthew; Sheean, Paul; Vallotton, Pascal; Zabaras, Dimitrios; Bird, Michael

    2013-01-01

    Vitamin D deficiency is widespread, affecting over 30% of adult Australians, and increasing up to 80% for at-risk groups including the elderly (age>65). The role for Vitamin D in development of the central nervous system is supported by the association between Vitamin D deficiency and incidence of neurological and psychiatric disorders including Alzheimer's disease (AD). A reported positive relationship between Vitamin D status and cognitive performance suggests that restoring Vitamin D status might provide a cognitive benefit to those with Vitamin D deficiency. Mushrooms are a rich source of ergosterol, which can be converted to Vitamin D2 by treatment with UV light, presenting a new and convenient dietary source of Vitamin D2. We hypothesised that Vitamin D2-enriched mushrooms (VDM) could prevent the cognitive and pathological abnormalities associated with dementia. Two month old wild type (B6C3) and AD transgenic (APPSwe/PS1dE9) mice were fed a diet either deficient in Vitamin D2 or a diet which was supplemented with VDM, containing 1±0.2 µg/kg (∼54 IU/kg) vitamin D2, for 7 months. Effects of the dietary intervention on memory were assessed pre- and post-feeding. Brain sections were evaluated for amyloid β (Aβ) plaque loads and inflammation biomarkers using immuno-histochemical methods. Plasma vitamin D metabolites, Aβ40, Aβ42, calcium, protein and cholesterol were measured using biochemical assays. Compared with mice on the control diet, VDM-fed wild type and AD transgenic mice displayed improved learning and memory, had significantly reduced amyloid plaque load and glial fibrillary acidic protein, and elevated interleukin-10 in the brain. The results suggest that VDM might provide a dietary source of Vitamin D2 and other bioactives for preventing memory-impairment in dementia. This study supports the need for a randomised clinical trial to determine whether or not VDM consumption can benefit cognitive performance in the wider population. PMID:24204618

  10. Neuroprotective effect of memantine on the retinal ganglion cells of APPswe/PS1ΔE9 mice and its immunomodulatory mechanisms.

    PubMed

    Gao, Lixiong; Chen, Xi; Tang, Yongping; Zhao, Jinghui; Li, Qiyou; Fan, Xiaotang; Xu, Haiwei; Yin, Zheng Qin

    2015-06-01

    Besides the cognitive impairment and degeneration in the brain, vision dysfunction and retina damage are always prevalent in patients with Alzheimer's disease (AD). The uncompetitive antagonist of the N-methyl-d-aspartate receptor, memantine (MEM), has been proven to improve the cognition of patients with AD. However, limited information exists regarding the mechanism of neurodegeneration and the possible neuroprotective mechanisms of MEM on the retinas of patients with AD. In the present study, by using APPswe/PS1ΔE9 double transgenic (dtg) mice, we found that MEM rescued the loss of retinal ganglion cells (RGCs), as well as improved visual impairments, including improving the P50 component in pattern electroretinograms and the latency delay of the P2 component in flash visual evoked potentials of APPswe/PS1ΔE9 dtg mice. The activated microglia in the retinas of APPswe/PS1ΔE9 dtg mice were also inhibited by MEM. Additionally, the level of glutamine synthetase expressed by Müller cells within the RGC layer was upregulated in APPswe/PS1ΔE9 dtg mice, which was inhibited by MEM. Simultaneously, MEM also reduced the apoptosis of choline acetyl transferase-immunoreactive cholinergic amacrine cells within the RGC layer of AD mice. Moreover, the phosphorylation level of extracellular regulated protein kinases 1 and 2 was increased in APPswe/PS1ΔE9 dtg mice, which was blocked by MEM treatment. These findings suggest that MEM protects RGCs in the retinas of APPswe/PS1ΔE9 dtg mice by modulating the immune response of microglia and the adapted response of Müller cells, making MEM a potential ophthalmic treatment alternative in patients with AD.

  11. Morin reverses neuropathological and cognitive impairments in APPswe/PS1dE9 mice by targeting multiple pathogenic mechanisms.

    PubMed

    Du, Ying; Qu, Jie; Zhang, Wei; Bai, Miao; Zhou, Qiong; Zhang, Zhuo; Li, Zhuyi; Miao, Jianting

    2016-09-01

    Alzheimer's disease (AD) is the most common form of dementia worldwide, characterized by progressive cognitive impairment and multiple distinct neuropathological features. Currently, there are no available therapies to delay or block the disease progression. Thus, the disease-modifying therapies are urgent for this devastating disorder by simultaneously targeting multiple distinct pathological processes. Morin, a natural bioflavonoid, have been shown to be strongly neuroprotective in vitro and in vivo. In this study, we first investigated the disease-modifying effects of chronic morin administration on the neuropathological and cognitive impairments in APPswe/PS1dE9 double transgenic mice. Our results showed that chronic morin administration prevented spatial learning and memory deficits in the APPswe/PS1dE9 mice. Morin treatment in the APPswe/PS1dE9 mice markedly reduced cerebral Aβ production and Aβ plaque burden via promoting non-amyloidogenic APP processing pathway by increasing ADAM10 expression, inhibiting amyloidogenic APP processing pathway by decreased BACE1 and PS1 expression, and facilitating Aβ degradation by enhancing Aβ-degrading enzyme expression. In addition, we also found that morin treatment in the APPswe/PS1dE9 mice markedly decreased tau hyperphosphorylation via its inhibitory effect on CDK5 signal pathway. Furthermore, morin treatment in the APPswe/PS1dE9 mice markedly reduced the activated glial cells and increased the expression of synaptic markers. Collectively, our findings demonstrate that chronic morin treatment restores cognitive functions and reverses multiple distinct neuropathological AD-like hallmarks in the APPswe/PS1dE9 mice. This study provides novel insights into the neuroprotective actions and neurobiological mechanisms of morin against AD, suggesting that morin is a potently promising disease-modifying agent for treatment of AD.

  12. Apolipoprotein A-I Deficiency Increases Cerebral Amyloid Angiopathy and Cognitive Deficits in APP/PS1ΔE9 Mice*

    PubMed Central

    Lefterov, Iliya; Fitz, Nicholas F.; Cronican, Andrea A.; Fogg, Allison; Lefterov, Preslav; Kodali, Ravindra; Wetzel, Ronald; Koldamova, Radosveta

    2010-01-01

    A hallmark of Alzheimer disease (AD) is the deposition of amyloid β (Aβ) in brain parenchyma and cerebral blood vessels, accompanied by cognitive decline. Previously, we showed that human apolipoprotein A-I (apoA-I) decreases Aβ40 aggregation and toxicity. Here we demonstrate that apoA-I in lipidated or non-lipidated form prevents the formation of high molecular weight aggregates of Aβ42 and decreases Aβ42 toxicity in primary brain cells. To determine the effects of apoA-I on AD phenotype in vivo, we crossed APP/PS1ΔE9 to apoA-IKO mice. Using a Morris water maze, we demonstrate that the deletion of mouse Apoa-I exacerbates memory deficits in APP/PS1ΔE9 mice. Further characterization of APP/PS1ΔE9/apoA-IKO mice showed that apoA-I deficiency did not affect amyloid precursor protein processing, soluble Aβ oligomer levels, Aβ plaque load, or levels of insoluble Aβ in brain parenchyma. To examine the effect of Apoa-I deletion on cerebral amyloid angiopathy, we measured insoluble Aβ isolated from cerebral blood vessels. Our data show that in APP/PS1ΔE9/apoA-IKO mice, insoluble Aβ40 is increased more than 10-fold, and Aβ42 is increased 1.5-fold. The increased levels of deposited amyloid in the vessels of cortices and hippocampi of APP/PS1ΔE9/apoA-IKO mice, measured by X-34 staining, confirmed the results. Finally, we demonstrate that lipidated and non-lipidated apoA-I significantly decreased Aβ toxicity against brain vascular smooth muscle cells. We conclude that lack of apoA-I aggravates the memory deficits in APP/PS1ΔE9 mice in parallel to significantly increased cerebral amyloid angiopathy. PMID:20739292

  13. Petite Amateur Navy Satellite (PANSAT)

    NASA Technical Reports Server (NTRS)

    Sakoda, D.; Hiser, J. K.

    1989-01-01

    The Naval Postgraduate School's (NPS) Space Systems Academic Group (SSAG) is designing and developing a small communications satellite for launch aboard the shuttle as a complex autonomous payload (CAP). The objectives of PANSAT are three-fold. First, PANSAT will provide an ideal educational tool for the officer students at NPS supporting Space Systems Engineering and Space Systems Operations with hands-on hardware development. Second, the satellite will provide digital store-and-forward communications, or packet radio, for the amateur radio community. The third objective is to provide a low-cost, space-based platform for small experiments. PANSAT will be launched from the shuttle at a nominal altitude of 200 n.m. and an inclination of at least 37 degrees. The satellite weight is 150 lbs. Since there is no attitude control, eight dipole whip antennas will be used to provide isotropic ground coverage for communications. FM digital communications will be used with up-link and down-link on a single frequency in the amateur band of 437.25 MHz. A maximum 50 kHz of bandwidth is envisioned for the satellite. The expected lifetime of the satellite is 1 1/2 to 2 years before atmospheric reentry. The PANSAT design consists of the following: communications subsystem (COMM); computer, or data processor and sequencer (DP&S); power subsystem; structure subsystem; and experiment payload.

  14. Galileo satellite antenna modeling

    NASA Astrophysics Data System (ADS)

    Steigenberger, Peter; Dach, Rolf; Prange, Lars; Montenbruck, Oliver

    2015-04-01

    The space segment of the European satellite navigation system Galileo currently consists of six satellites. Four of them belong to the first generation of In-Orbit Validation (IOV) satellites whereas the other two are Full Operational Capability (FOC) satellites. High-precision geodetic applications require detailed knowledge about the actual phase center of the satellite and receiver antenna. The deviation of this actual phase center from a well-defined reference point is described by phase center offsets (PCOs) and phase center variations (PCVs). Unfortunately, no public information is available about the Galileo satellite antenna PCOs and PCVs, neither for the IOV, nor the FOC satellites. Therefore, conventional values for the IOV satellite antenna PCOs have been adopted for the Multi-GNSS experiment (MGEX) of the International GNSS Service (IGS). The effect of the PCVs is currently neglected and no PCOs for the FOC satellites are available yet. To overcome this deficiency in GNSS observation modeling, satellite antenna PCOs and PCVs are estimated for the Galileo IOV satellites based on global GNSS tracking data of the MGEX network and additional stations of the legacy IGS network. Two completely independent solutions are computed with the Bernese and Napeos software packages. The PCO and PCV values of the individual satellites are analyzed and the availability of two different solutions allows for an accuracy assessment. The FOC satellites are built by a different manufacturer and are also equipped with another type of antenna panel compared to the IOV satellites. Signal transmission of the first FOC satellite has started in December 2014 and activation of the second satellite is expected for early 2015. Based on the available observations PCO estimates and, optionally PCVs of the FOC satellites will be presented as well. Finally, the impact of the new antenna model on the precision and accuracy of the Galileo orbit determination is analyzed.

  15. [Fundamental study of memory impairment and non-cognitive behavioral alterations in APPswe/PS1dE9 mice].

    PubMed

    Taniuchi, Nobuhiko; Niidome, Tetsuhiro; Sugimoto, Hachiro

    2015-01-01

    In addition to cognitive decline, Alzheimer's disease patients also exhibit non-cognitive symptoms commonly referred to as behavioral and psychological symptoms of dementia, or BPSD. These symptoms have a serious impact on the quality of life of these patients, as well as that of their caregivers, but there are currently no effective therapies. The amyloid β-peptide (Aβ) is suspected to play a central role in the cascade leading to Alzheimer's disease, but the precise mechanisms are still incompletely known. To assess the influence of Aβ pathology on cognitive and non-cognitive behaviors, we examined locomotor activity, motor coordination, and spatial memory in male and female APPswePS1dE9 mice (Alzheimer's disease model, double transgenic mice expressing an amyloid precursor protein with Swedish mutation and a presenilin-1 with deletion of exon 9) at 5 months of age, when the mice had subtle Aβ deposits, and again at 9 months of age, when the mice had numerous Aβ deposits. Compared to wild-type mice, the male and female APPswe/PS1dE9 mice showed normal motor coordination in the rotarod test at both 5 and 9 months. In the Morris water maze test, male and female APPswe/PS1dE9 mice showed impaired spatial memory at 9 months; however, no such deficits were found at 5 months. In a locomotor activity test, male APPswe/PS1dE9 mice exhibited locomotor hyperactivity at 9 months, while females exhibited locomotor hyperactivity at both 5 and 9 months compared to the control mice. Together, these results indicate that APPswe/PS1dE9 mice developed spatial memory impairment and BPSD-like behavioral alterations resulting from Aβ accumulation.

  16. [Fundamental study of memory impairment and non-cognitive behavioral alterations in APPswe/PS1dE9 mice].

    PubMed

    Taniuchi, Nobuhiko; Niidome, Tetsuhiro; Sugimoto, Hachiro

    2015-01-01

    In addition to cognitive decline, Alzheimer's disease patients also exhibit non-cognitive symptoms commonly referred to as behavioral and psychological symptoms of dementia, or BPSD. These symptoms have a serious impact on the quality of life of these patients, as well as that of their caregivers, but there are currently no effective therapies. The amyloid β-peptide (Aβ) is suspected to play a central role in the cascade leading to Alzheimer's disease, but the precise mechanisms are still incompletely known. To assess the influence of Aβ pathology on cognitive and non-cognitive behaviors, we examined locomotor activity, motor coordination, and spatial memory in male and female APPswePS1dE9 mice (Alzheimer's disease model, double transgenic mice expressing an amyloid precursor protein with Swedish mutation and a presenilin-1 with deletion of exon 9) at 5 months of age, when the mice had subtle Aβ deposits, and again at 9 months of age, when the mice had numerous Aβ deposits. Compared to wild-type mice, the male and female APPswe/PS1dE9 mice showed normal motor coordination in the rotarod test at both 5 and 9 months. In the Morris water maze test, male and female APPswe/PS1dE9 mice showed impaired spatial memory at 9 months; however, no such deficits were found at 5 months. In a locomotor activity test, male APPswe/PS1dE9 mice exhibited locomotor hyperactivity at 9 months, while females exhibited locomotor hyperactivity at both 5 and 9 months compared to the control mice. Together, these results indicate that APPswe/PS1dE9 mice developed spatial memory impairment and BPSD-like behavioral alterations resulting from Aβ accumulation. PMID:25747232

  17. Stereo Measurements from Satellites

    NASA Technical Reports Server (NTRS)

    Adler, R.

    1982-01-01

    The papers in this presentation include: 1) 'Stereographic Observations from Geosynchronous Satellites: An Important New Tool for the Atmospheric Sciences'; 2) 'Thunderstorm Cloud Top Ascent Rates Determined from Stereoscopic Satellite Observations'; 3) 'Artificial Stereo Presentation of Meteorological Data Fields'.

  18. Satellite-Delivered Learning.

    ERIC Educational Resources Information Center

    Arnall, Gail C.

    1987-01-01

    Discusses the application of satellite information delivery to training. Describes a new trend, horizontal programming. Also discusses vertical programming and in-house production of training materials. Lists vendors of satellite-based training. (CH)

  19. Geology of icy satellites

    NASA Technical Reports Server (NTRS)

    Mckinnon, W. B.

    1985-01-01

    The geology of the major icy satellites of Jupiter, Saturn, Uranus, and Neptune is discussed in terms of the four major processes that shape icy satellite surfaces: impact cratering, volcanism, tectonism, and interactions with planetary magnetospheres and solar radiation. The role of these processes in creating the differences that exist among the satellites, in particular the orderly progression of geological properties in the Jovian satellites, is emphasized. Important questions left open after the Voyager missions are summarized.

  20. Magnetospheres: Jupiter, Satellite Interactions

    NASA Astrophysics Data System (ADS)

    Neubauer, F.; Murdin, P.

    2000-11-01

    Most of the satellites of Jupiter, notably the large Galilean satellites Io, Europa, Ganymede and Callisto (see JUPITER: SATELLITES), orbit deep inside the magnetosphere of Jupiter (see JUPITER: MAGNETOSPHERE) and are therefore immersed in the flow of magnetospheric plasma (made of a mixture of electrons and ions) and subjected to an interaction with the strong Jovian magnetic field. These intera...

  1. Vitamin D2-Enriched Button Mushroom (Agaricus bisporus) Improves Memory in Both Wild Type and APPswe/PS1dE9 Transgenic Mice

    PubMed Central

    Bennett, Louise; Kersaitis, Cindy; Macaulay, Stuart Lance; Münch, Gerald; Niedermayer, Garry; Nigro, Julie; Payne, Matthew; Sheean, Paul; Vallotton, Pascal; Zabaras, Dimitrios; Bird, Michael

    2013-01-01

    Vitamin D deficiency is widespread, affecting over 30% of adult Australians, and increasing up to 80% for at-risk groups including the elderly (age>65). The role for Vitamin D in development of the central nervous system is supported by the association between Vitamin D deficiency and incidence of neurological and psychiatric disorders including Alzheimer’s disease (AD). A reported positive relationship between Vitamin D status and cognitive performance suggests that restoring Vitamin D status might provide a cognitive benefit to those with Vitamin D deficiency. Mushrooms are a rich source of ergosterol, which can be converted to Vitamin D2 by treatment with UV light, presenting a new and convenient dietary source of Vitamin D2. We hypothesised that Vitamin D2-enriched mushrooms (VDM) could prevent the cognitive and pathological abnormalities associated with dementia. Two month old wild type (B6C3) and AD transgenic (APPSwe/PS1dE9) mice were fed a diet either deficient in Vitamin D2 or a diet which was supplemented with VDM, containing 1±0.2 µg/kg (∼54 IU/kg) vitamin D2, for 7 months. Effects of the dietary intervention on memory were assessed pre- and post-feeding. Brain sections were evaluated for amyloid β (Aβ) plaque loads and inflammation biomarkers using immuno-histochemical methods. Plasma vitamin D metabolites, Aβ40, Aβ42, calcium, protein and cholesterol were measured using biochemical assays. Compared with mice on the control diet, VDM-fed wild type and AD transgenic mice displayed improved learning and memory, had significantly reduced amyloid plaque load and glial fibrillary acidic protein, and elevated interleukin-10 in the brain. The results suggest that VDM might provide a dietary source of Vitamin D2 and other bioactives for preventing memory-impairment in dementia. This study supports the need for a randomised clinical trial to determine whether or not VDM consumption can benefit cognitive performance in the wider population. PMID

  2. Clusters in an intrinsically disordered protein create a protein-binding site: the TolB-binding region of colicin E9.

    PubMed

    Tozawa, Kaeko; Macdonald, Colin J; Penfold, Christopher N; James, Richard; Kleanthous, Colin; Clayden, Nigel J; Moore, Geoffrey R

    2005-08-30

    The 61-kDa colicin E9 protein toxin enters the cytoplasm of susceptible cells by interacting with outer membrane and periplasmic helper proteins and kills them by hydrolyzing their DNA. The membrane translocation function is located in the N-terminal domain of the colicin, with a key signal sequence being a pentapeptide region that governs the interaction with the helper protein TolB (the TolB box). Previous NMR studies [Collins et al. (2002) J. Mol. Biol. 318, 787-904; MacDonald et al. (2004), J. Biomol. NMR 30, 81-96] have shown that the N-terminal 83 residues of colicin E9, which includes the TolB box, is intrinsically disordered and contains clusters of interacting side chains. To further define the properties of this region of colicin E9, we have investigated the effects on the dynamical and TolB-binding properties of three mutations of colicin E9 that inactivate it as a toxin. The mutations were contained in a fusion protein consisting of residues 1-61 of colicin E9 connected to the N terminus of the E9 DNase by an eight-residue linking sequence. The NMR data reveals that the mutations cause major alterations to the properties of some of the clusters, consistent with some form of association between them and other more distant parts of the amino acid sequence, particularly toward the N terminus of the protein. However, (15)N T(2) measurements indicates that residues 5-13 of the fusion protein bound to the 43-kDa TolB remain as flexible as they are in the free protein. The NMR data point to considerable dynamic ordering within the intrinsically disordered translocation domain of the colicin that is important for creating the TolB-binding site. Furthermore, amino acid sequence considerations suggest that the clusters of amino acids occur because of the size and polarities of the side chains forming them influenced by the propensities of the residues within the clusters and those immediately surrounding them in sequence space to form beta turns. PMID:16114886

  3. Survey: National Environmental Satellite Service

    NASA Technical Reports Server (NTRS)

    1977-01-01

    The national Environmental Satellite Service (NESS) receives data at periodic intervals from satellites of the Synchronous Meteorological Satellite/Geostationary Operational Environmental Satellite series and from the Improved TIROS (Television Infrared Observational Satellite) Operational Satellite. Within the conterminous United States, direct readout and processed products are distributed to users over facsimile networks from a central processing and data distribution facility. In addition, the NESS Satellite Field Stations analyze, interpret, and distribute processed geostationary satellite products to regional weather service activities.

  4. Fundamentals of satellite navigation

    NASA Astrophysics Data System (ADS)

    Stiller, A. H.

    The basic operating principles and capabilities of conventional and satellite-based navigation systems for air, sea, and land vehicles are reviewed and illustrated with diagrams. Consideration is given to autonomous onboard systems; systems based on visible or radio beacons; the Transit, Cicada, Navstar-GPS, and Glonass satellite systems; the physical laws and parameters of satellite motion; the definition of time in satellite systems; and the content of the demodulated GPS data signal. The GPS and Glonass data format frames are presented graphically, and tables listing the GPS and Glonass satellites, their technical characteristics, and the (past or scheduled) launch dates are provided.

  5. Geosynchronous satellite collision avoidance

    NASA Technical Reports Server (NTRS)

    Fraser, W.

    1985-01-01

    The increases in the number of satellite systems, the growing dependency on these systems, and the potentially hazardous conjunctions in space, dictates careful management of satellite positions. The potential for satellite collision increases as more objects are placed in orbit. At geosynchronous altitudes active satellites maintain fixed longitudinal station-keeping control while inactive satellites and debris generally drift around the globe or oscillate about two geopotential stable points. Portions of the total objects in geosynchronous orbit are tracked by ground stations while a significant number of additional pieces of space debris regularly pass through geosynchronous orbit altitudes. The probability of an operational satellite colliding with another satellite or a piece of space debris will increase in the number of space objects, their sizes, and on-orbit lifetimes.

  6. A CCD comparison of outer Jovian satellites and Trojan asteroids

    NASA Technical Reports Server (NTRS)

    Luu, Jane X.

    1991-01-01

    The eight small outer Jovian satellites are not as well known as the brighter, more illustrious Galilean satellites. They are divided into two groups, each containing four satellites; the inner group travels in prograde orbits while the outer group travels in retrograde orbits. From the distinct orbital characteristics of the two groups, most of the theories of their origin involve the capture and breakup of two planetesimals upon entry into the atmosphere of proto-Jupiter. Their proximity to the Trojans asteroids has led to conjectures of a link between them and the Trojans. However, Tholen and Zellner (1984) found no red spectrum among six of the satellites and postulated that they were all C-type objects; therefore, they were unlikely to be derivatives of the Trojan population. Charge-coupled device (CCD) photometry and spectroscopy of the eight outer Jovian satellites obtained from 1987 to 1989 and a comparison between these eight satellites and the Trojan asteroids are presented.

  7. Comments on satellite meteorology from geostationary satellites

    NASA Technical Reports Server (NTRS)

    Vonderhaar, T. H.

    1982-01-01

    Examples of the use of geostationary satellites in meteorology are given. Studies of the rate of change of cumulus clouds and cloud systems and wind parameter determination from cloud motions are reviewed. Computer processed imagery products are also discussed.

  8. Reduction of low-density lipoprotein receptor-related protein (LRP1) in hippocampal neurons does not proportionately reduce, or otherwise alter, amyloid deposition in APPswe/PS1dE9 transgenic mice

    PubMed Central

    2012-01-01

    Introduction The low-density lipoprotein receptor-related protein (LRP1) and its family members have been implicated in the pathogenesis of Alzheimer's disease. Multiple susceptibility factors converge to metabolic pathways that involve LRP1, including modulation of the processing of amyloid precursor protein (APP) and the clearance of Aβ peptide. Methods We used the Cre-lox system to lower LRP1 levels in hippocampal neurons of mice that develop Alzheimer-type amyloid by crosses between mice that express Cre recombinase under the transcriptional control of the GFAP promoter, mice that harbor loxp sites in the LRP1 gene, and the APPswe/PS1dE9 transgenic model. We compared amyloid plaque numbers in APPswe/PS1dE9 mice lacking LRP1 expression in hippocampus (n = 13) to mice with normal levels of LRP1 (n = 12). Student t-test was used to test whether there were significant differences in plaque numbers and amyloid levels between the groups. A regression model was used to fit two regression lines for these groups, and to compare the rates of Aβ accumulation. Results Immunohistochemical analyses demonstrated efficient elimination of LRP1 expression in the CA fields and dentate gyrus of the hippocampus. Within hippocampus, we observed no effect on the severity of amyloid deposition, the rate of Aβ40/42 accumulation, or the architecture of amyloid plaques when LRP1 levels were reduced. Conclusions Expression of LRP1 by neurons in proximity to senile amyloid plaques does not appear to play a major role in modulating the formation of these proximal deposits or in the appearance of the associated neuritic pathology. PMID:22537779

  9. Workshop on Satellite Meteorology. Part 2; Satellite Image Analysis and Interpretation

    NASA Technical Reports Server (NTRS)

    1982-01-01

    The Workshop on Satellite Meteorology is co-sponsored by the Cooperative Institute for Research in the Atmosphere (CIRA) at Colorado State University and the American Meteorological Society's Committee on Meteorological Aspects of Aerospace Systems. The workshop covers uses of satellite data in atmospheric science. It provides state-of-the-art information to those in Universities, research groups, and other users. One area of primary focus is to provide source material to university personnel for developing and augmenting courses in satellite meteorology and the atmospheric sciences. The items in the program include information on meteorological satellites and data sources, uses of satellite imagery for all scales of weather analysis and forecasting, uses of sounding data and other radiance information and research opportunities on interactive systems. Each session is presented by a group of experts in the field and includes an open discussion of the state-of-the-art and promising areas for future development. This pre-print volume is one of three parts on the workshop. The three parts are: PART I. Satellites and Their Data; PART II. Satellite Image Analysis and Interpretation; PART III. Satellite Soundings and Their Uses.

  10. Satellite services system overview

    NASA Technical Reports Server (NTRS)

    Rysavy, G.

    1982-01-01

    The benefits of a satellite services system and the basic needs of the Space Transportation System to have improved satellite service capability are identified. Specific required servicing equipment are discussed in terms of their technology development status and their operative functions. Concepts include maneuverable television systems, extravehicular maneuvering unit, orbiter exterior lighting, satellite holding and positioning aid, fluid transfer equipment, end effectors for the remote manipulator system, teleoperator maneuvering system, and hand and power tools.

  11. Satellite Antenna Systems

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Through the Technology Affiliates Program at the Jet Propulsion Laboratory, the ACTS antenna system was transferred from experimental testing status to commercial development with KVH Industries, Inc. The ACTS design enables mobile satellite antennas to remain pointed at the satellite, regardless of the motion or vibration on which it is mounted. KVH's first product based on the ACTS design is a land-mobile satellite antenna system that will enable direct broadcast satellite television aboard moving trucks, recreational vehicles, trains, and buses. Future products could include use in broadcasting, emergency medical and military vehicles.

  12. Satellite communication antenna technology

    NASA Technical Reports Server (NTRS)

    Mittra, R. (Editor); Imbriale, W. A. (Editor); Maanders, E. J. (Editor)

    1983-01-01

    A general overview of current technology in the field of communication satellite antennas is presented. Among the topics discussed are: the design of multiple beam systems; frequency reuse; and polarization control of antenna measurements. Consideration is also given to: contour beam synthesis; dual shaped reflector synthesis; beam shaping; and offset reflector design. The applications of the above technologies to present and future generations of communications satellites is considered, with emphasis given to such systems as: the Intelsats; the Defense Satellite Communications System, (DSCS-III); Satellite Business System (SBS), and Comstar.

  13. Satellite networks for education

    NASA Technical Reports Server (NTRS)

    Singh, J. P.; Morgan, R. P.; Rosenbaum, F. J.

    1972-01-01

    Satellite based educational networking is discussed with particular attention given to the potential uses of communications satellites to help meet educational needs in the United states. Four major subject areas were covered; (1) characteristics and structure of networks, (2) definition of pressures within educational establishment that provide motivation for various types of networks, (3) examination of current educational networking status for educational radio and television, instructional television fixed services, inter- and intra-state educational communication networks, computer networks, and cable television for education, and (4) identification of possible satellite based educational telecommunication services and three alternatives for implementing educational satellite systems.

  14. Soluble Aβ levels correlate with cognitive deficits in the 12-month-old APPswe/PS1dE9 mouse model of Alzheimer's disease.

    PubMed

    Zhang, Wei; Hao, Jian; Liu, Rui; Zhang, Zhuo; Lei, Gesheng; Su, Changjun; Miao, Jianting; Li, Zhuyi

    2011-09-23

    Amyloid-beta peptide (Aβ) is believed to be central in the pathogenesis of Alzheimer's disease (AD) characterized by cognitive deficits. However, it remains uncertain which form(s) of Aβ pathology is responsible for the cognitive deficits in AD. In the present study, the cognitive deficits and the profiles of Aβ pathology were characterized in the 12-month-old APPswe/PS1dE9 double transgenic mice, and their correlations were examined. Compared with non-transgenic littermates, the middle-aged APPswe/PS1dE9 mice exhibited spatial learning and memory deficits in the water maze test and long-term contextual memory deficits in the step-down passive avoidance test. Among the middle-aged APPswe/PS1dE9 mice, hippocampal soluble Aβ1-40 and Aβ1-42 levels were highly correlated with spatial learning deficits and long-term contextual memory deficits, as well as cortical and hippocampal soluble Aβ1-40 and Aβ1-42 levels were strongly correlated with spatial memory deficits. By contrast, no significant correlations were observed between three measures of cognitive functions and amyloid plaque burden (total Aβ plaque load and fibrillar Aβ plaque load), total Aβ levels (Aβ1-40 and Aβ1-42), as well as insoluble Aβ levels (Aβ1-40 and Aβ1-42). Stepwise multiple regression analysis identified hippocampal soluble Aβ1-40 and Aβ1-42 levels as independent factors for predicting the spatial learning deficits and the long-term contextual memory deficits, as well as hippocampal and cortical soluble Aβ1-40 and Aβ1-42 levels as independent factors for predicting the spatial memory deficits in transgenic mice. These results demonstrate that cognitive deficits are highly related to the levels of soluble Aβ in middle-aged APPswe/PS1dE9 mice, in which soluble Aβ levels are only a tiny fraction of the amount of total Aβ levels. Consequently, our findings provide further evidence that soluble Aβ might primarily contribute to cognitive deficits in AD, suggesting that reducing

  15. Satellite Teleconference Final Report.

    ERIC Educational Resources Information Center

    Elgin Community Coll., IL.

    The vocational education satellite teleconference project accomplished two goals: (1) identified, acquired, copied, and distributed to the Illinois Vocational Curriculum Center 100 marketing or training videotapes for staff development and classroom use; and (2) provided from 15-25 variable time (1- to 3-hour) satellite teleconferences in four…

  16. Communication satellite technology trends

    NASA Technical Reports Server (NTRS)

    Cuccia, Louis

    1986-01-01

    A chronology of space-Earth interconnectivity is presented. The Advanced Communications Technology Satellite (ACTS) system, Land Mobile Satellite, space-Earth antennas, impact of antenna size on coverage, intersatellite links are outlined. This presentation is represented by graphs and charts only.

  17. Satellites in Schools.

    ERIC Educational Resources Information Center

    Underwood, C. I.; And Others

    1987-01-01

    Discusses the use of satellite data in physics classrooms. Describes the apparatus that can be used to collect and analyze data. Provides examples of how telemetry data transmitted by the satellite UoSAT-2 can be used not only in teaching physics, but also in geography, mathematics, and information technology. (TW)

  18. Signals from Communications Satellites.

    ERIC Educational Resources Information Center

    Thomsen, Volker

    1996-01-01

    Discusses the Doppler effect for relative motion between a source of waves and an observer and the orbital dynamics of communications satellites. Presents preliminary calculations of the satellite's altitude and linear velocity using only the concepts of the Doppler shift and the mechanics of motion in a circular path. (JRH)

  19. Audio direct broadcast satellites

    NASA Astrophysics Data System (ADS)

    Miller, J. E.

    1983-05-01

    Satellite sound broadcasting is, as the name implies, the use of satellite techniques and technology to broadcast directly from space to low-cost, consumer-quality receivers the types of sound programs commonly received in the AM and FM broadcast bands. It would be a ubiquitous service available to the general public in the home, in the car, and out in the open.

  20. Seminar by Satellite

    ERIC Educational Resources Information Center

    Hart, Peter J.

    1978-01-01

    Seminars on curriculum development transmitted by satellite are operated by the University of the South Pacific, Suva. The satellite was launched in 1966 by NASA, which has permitted educational broadcasting. Ground stations have been set up in eight countries that support the university. Practical aspects of transmission are outlined. (SW)

  1. Audio direct broadcast satellites

    NASA Technical Reports Server (NTRS)

    Miller, J. E.

    1983-01-01

    Satellite sound broadcasting is, as the name implies, the use of satellite techniques and technology to broadcast directly from space to low-cost, consumer-quality receivers the types of sound programs commonly received in the AM and FM broadcast bands. It would be a ubiquitous service available to the general public in the home, in the car, and out in the open.

  2. Satellites and the ISDN

    NASA Astrophysics Data System (ADS)

    Lewis, J.

    1983-12-01

    The potential role of satellites in an integrated services digital network (ISDN) is discussed in the light of recent CCITT studies. Present satellite digital-communication techniques are reviewed, and the changes introduced by ISDN development and by the competition of long-distance optical-fiber networks are characterized. CCITT standards on error performance (e.g., bit-error rate less than 10 to the -6th for at least 98 percent of the worst month), availability, and synchronization are summarized and compared with currently applied satellite standards. Since the potential for improvements in transmission quality and delay in satellite systems is limited, it is recommended that satellite planning concentrate on transparency enhancement (including speech processing, frame-format modification, and forward error correction) to accommodate ISDN.

  3. Thermal imbalance force modelling for a GPS satellite using the finite element method

    NASA Technical Reports Server (NTRS)

    Vigue, Yvonne; Schutz, Bob E.

    1991-01-01

    Methods of analyzing the perturbation due to thermal radiation and determining its effects on the orbits of GPS satellites are presented, with emphasis on the FEM technique to calculate satellite solar panel temperatures which are used to determine the magnitude and direction of the thermal imbalance force. Although this force may not be responsible for all of the force mismodeling, conditions may work in combination with the thermal imbalance force to produce such accelerations on the order of 1.e-9 m/sq s. If submeter accurate orbits and centimeter-level accuracy for geophysical applications are desired, a time-dependent model of the thermal imbalance force should be used, especially when satellites are eclipsing, where the observed errors are larger than for satellites in noneclipsing orbits.

  4. Transit satellite system timing capabilities

    NASA Technical Reports Server (NTRS)

    Finsod, T. D.

    1978-01-01

    Current time transfer capabilities of the Transit Satellite System are reviewed. Potential improvements in the changes in equipment and operational procedures using operational satellites are discussed.

  5. Satellite Services Workshop, Volume 1

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Key issues associated with the orbital servicing of satellites are examined including servicing spacecraft and equipment, servicing operations, economics, satellite design, docking and berthing, and fluid management.

  6. Videoconferencing via satellite. Opening Congress to the people: Technical report

    NASA Technical Reports Server (NTRS)

    Wood, F. B.; Coates, V. T.; Chartrand, R. L.; Ericson, R. F.

    1978-01-01

    The feasibility of using satellite videoconferencing as a mechanism for informed dialogue between Congressmen and constituents to strengthen the legislative process was evaluated. Satellite videoconferencing was defined as a two-way interactive television with the TV signals transmitted by satellite. With videoconferencing, one or more Congressmen in Washington, D. C. can see, hear and talk with groups of citizens at distant locations around the country. Simultaneously, the citizens can see, hear and talk with the Congressmen.

  7. Swedish small satellites

    NASA Astrophysics Data System (ADS)

    Lundahl, K.; von Scheele, F.

    2004-11-01

    In 1986 the first Swedish small satellite VIKING was launched on the Ariane 1 rocket together with the French remote sensing satellite SPOT-1. This paper describes the development of Swedish small satellites in an international framework. The satellites have delivered excellent scientific data to a low cost by using e.g. streamlined project organisations, competitive procurement programs and piggy-back launch opportunities. The first micro satellite Astrid-1 was launched in January 1995 and was followed by the launch of Astrid-2 in December 1998. The capable Odin small satellite was launched in February 2001. SSC was also contracted for ESA's SMART-1 probe destined to the Moon. SMART-1, launched in September 2003, is used for both research and as a technology demonstrator for future projects. Future proposed projects include micro and small satellites for climate research as the Atmosphere and Climate Explorer Plus (ACE+), the Stratosphere-Troposphere Exchange And climate Monitor (STEAM) and PRISMA, a technology demonstrator for formation flying, new propulsion system and commercial development methods.

  8. Satellite remote sensing of vegetation

    NASA Astrophysics Data System (ADS)

    Mahr, Tobias; Peper, Eva; Schubert, Alexander; Warnach, Simon; Pöhler, Denis; Horbanski, Martin; Beirle, Steffen; Mies, Kornelia; Platt, Ulrich; Wagner, Thomas

    2013-04-01

    DOAS (Differential Optical Absorption Spectroscopy) allows to determine the concentration of trace gases based on their specific absorptions cross-sections along a light path. Since 1995, this principle is employed successfully on satellite-based instruments like GOME, GOME-2 and SCIAMACHY for the global measurement of stratospheric and tropospheric trace gases like ozone and nitrogen oxides. Usually, spectral signatures from the ground, where a big part of the sunlight is reflected, are neglected in the evaluation. This can lead to errors in the trace gas determination. However, these structures offer the opportunity to identify surface properties of the earth and different types of vegetation. To analyse spectral reflectance properties, high resolved reflection spectra (FWHM 0.29 nm) from 95 plants were measured between 350 and 1050 nm. They can serve as a basis for the analysis of satellite data. Including different vegetation reference spectra, it is possible to determine groups of plants with similar optical properties. This allows to derive global maps of the spatio-temporal variation of plant distribution by satellite remote sensing. We present first results of this technique based on SCIAMACHY observations.

  9. Skeletal muscle satellite cells

    NASA Technical Reports Server (NTRS)

    Schultz, E.; McCormick, K. M.

    1994-01-01

    Evidence now suggests that satellite cells constitute a class of myogenic cells that differ distinctly from other embryonic myoblasts. Satellite cells arise from somites and first appear as a distinct myoblast type well before birth. Satellite cells from different muscles cannot be functionally distinguished from one another and are able to provide nuclei to all fibers without regard to phenotype. Thus, it is difficult to ascribe any significant function to establishing or stabilizing fiber type, even during regeneration. Within a muscle, satellite cells exhibit marked heterogeneity with respect to their proliferative behavior. The satellite cell population on a fiber can be partitioned into those that function as stem cells and those which are readily available for fusion. Recent studies have shown that the cells are not simply spindle shaped, but are very diverse in their morphology and have multiple branches emanating from the poles of the cells. This finding is consistent with other studies indicating that the cells have the capacity for extensive migration within, and perhaps between, muscles. Complexity of cell shape usually reflects increased cytoplasmic volume and organelles including a well developed Golgi, and is usually associated with growing postnatal muscle or muscles undergoing some form of induced adaptive change or repair. The appearance of activated satellite cells suggests some function of the cells in the adaptive process through elaboration and secretion of a product. Significant advances have been made in determining the potential secretion products that satellite cells make. The manner in which satellite cell proliferative and fusion behavior is controlled has also been studied. There seems to be little doubt that cellcell coupling is not how satellite cells and myofibers communicate. Rather satellite cell regulation is through a number of potential growth factors that arise from a number of sources. Critical to the understanding of this form

  10. Satellite Breakup Risk Mitigation

    NASA Technical Reports Server (NTRS)

    Leleux, Darrin P.; Smith, Jason T.

    2006-01-01

    Many satellite breakups occur as a result of an explosion of stored energy on-board spacecraft or rocket-bodies. These breakups generate a cloud of tens or possibly hundreds of thousands of debris fragments which may pose a transient elevated threat to spaceflight crews and vehicles. Satellite breakups pose a unique threat because the majority of the debris fragments are too small to be tracked from the ground. The United States Human Spaceflight Program is currently implementing a risk mitigation strategy that includes modeling breakup events, establishing action thresholds, and prescribing corresponding mitigation actions in response to satellite breakups.

  11. Probability of satellite collision

    NASA Technical Reports Server (NTRS)

    Mccarter, J. W.

    1972-01-01

    A method is presented for computing the probability of a collision between a particular artificial earth satellite and any one of the total population of earth satellites. The collision hazard incurred by the proposed modular Space Station is assessed using the technique presented. The results of a parametric study to determine what type of satellite orbits produce the greatest contribution to the total collision probability are presented. Collision probability for the Space Station is given as a function of Space Station altitude and inclination. Collision probability was also parameterized over miss distance and mission duration.

  12. JOI reaffirms satellite plan

    NASA Astrophysics Data System (ADS)

    Katzoff, Judith A.

    A recent report by the Satellite Planning Committee of Joint Oceanographic Institutions, Inc. (JOI), Washington, D.C., underscored the need for the four oceanographic satellite missions that have been proposed for the next decade to be carried out as planned and firmly on schedule. In reaffirming the need for the missions, the committee said that many important types of long-term global data auoui ihe oceans can be gathered only by research satellites. The potential benefits to vital national activities such as trade, fisheries, national defense, and waste disposal will be well worth the missions' cost, they added.

  13. CONSTELL: NASA's Satellite Constellation Model

    NASA Technical Reports Server (NTRS)

    Theall, Jeffrey R.; Krisko, Paula H.; Opiela, John N.; McKay, Gordon A. (Technical Monitor)

    1999-01-01

    The CONSTELL program represents an initial effort by the orbital debris modeling group at NASA/JSC to address the particular issues and problems raised by the presence of LEO satellite constellations. It was designed to help NASA better understand the potential orbital debris consequences of having satellite constellations operating in the future in LEO. However, it could also be used by constellation planners to evaluate architecture or design alternatives that might lessen debris consequences for their constellation or lessen the debris effects on other users of space. CONSTELL is designed to perform debris environment projections rapidly so it can support parametric assessments involving either the constellations themselves or the background environment which represents non-constellation users of the space. The projections need to be calculated quickly because a number of projections are often required to adequately span the parameter space of interest. To this end CONSTELL uses the outputs of other NASA debris environment models as inputs, thus doing away with the need for time consuming upfront calculations. Specifically, CONSTELL uses EVOLVE or ORDEM96 debris spatial density results as its background environment, debris cloud snapshot templates to simulate debris cloud propagation, and time dependent orbit profiles of the intact non- functional constellation spacecraft and upper stages. In this paper the environmental consequences of the deployment of particular LEO satellite constellations using the CONSTELL model will be evaluated. Constellations that will undergo a parametric assessment will reflect realistic parameter values. Among other results the increase in loss rate of non-constellation spacecraft, the number of collisions involving constellation elements, and the replacement rate of constellation satellites as a result of debris impact will be presented.

  14. Overview of commercial satellite communications

    NASA Astrophysics Data System (ADS)

    Beakley, G. W.

    1984-07-01

    A brief history of communications satellites is presented, taking into account the launching of Sputnik 1 in October 1957, the Explorer 1 in January of 1958, the launch of the Score as the world's first active communications satellite in December 1958, the Communications Satellite Act in 1962, and the launch of 'Early Bird' in 1964. The Intelsat satellites are considered along with maritime satellite communications, the U.S. domestic satellite systems, Alaskan satellite communications, cable television, broadcast TV stations, print media, the hotel/motel industry as a large market for satellite communications terminals, the opening of a minicable and satellite master antenna TV market for TV receive-only systems, and business telecommunications earth terminals. Attention is also given to future directions regarding satellite positions, the concept of 'video-plus', and direct broadcast satellites.

  15. User applications unique to mobile satellites

    NASA Astrophysics Data System (ADS)

    Castiel, David

    As AMSC enters the market with its mobile satellite services, it faces a sophisticated user group that has already experimented with a wide range of communications services, including cellular radio and Ku-band satellite messaging. AMSC's challenge is to define applications unique to the capabilities of its dedicated L band satellite and consistent with the provisions outlined in its FCC license. Through a carefully researched approach to its three main markets (aeronautical, land mobile, and maritime) AMSC is discovering a wellspring of interest in corporate and general aviation, trucking companies, pipeline monitoring and control companies, maritime management firms, telecommunications companies, and government agencies. A general overview is provided of AMSC's FCC license and corporate history, and the specific applications unique to each user group is discussed.

  16. Orbit determination accuracies using satellite-to-satellite tracking

    NASA Technical Reports Server (NTRS)

    Vonbun, F. O.; Argentiero, P. D.; Schmid, P. E.

    1977-01-01

    The uncertainty in relay satellite sate is a significant error source which cannot be ignored in the reduction of satellite-to-satellite tracking data. Based on simulations and real data reductions, it is numerically impractical to use simultaneous unconstrained solutions to determine both relay and user satellite epoch states. A Bayesian or least squares estimation technique with an a priori procedure is presented which permits the adjustment of relay satellite epoch state in the reduction of satellite-to-satellite tracking data without the numerical difficulties introduced by an ill-conditioned normal matrix.

  17. The reionization of galactic satellite populations

    SciTech Connect

    Ocvirk, P.; Gillet, N.; Aubert, D.; Chardin, J.; Knebe, A.; Yepes, G.; Libeskind, N.; Gottlöber, S.; Hoffman, Y.

    2014-10-10

    We use high-resolution simulations of the formation of the local group, post-processed by a radiative transfer code for UV photons, to investigate the reionization of the satellite populations of an isolated Milky Way-M31 galaxy pair in a variety of scenarios. We use an improved version of ATON which includes a simple recipe for radiative feedback. In our baseline models, reionization is initiated by low-mass, radiatively regulated halos at high redshift, until more massive halos appear, which then dominate and complete the reionization process. We investigate the relation between reionization history and present-day positions of the satellite population. We find that the average reionization redshift (z {sub r}) of satellites is higher near galaxy centers (MW and M31). This is due to the inside out reionization patterns imprinted by massive halos within the progenitor during the epoch of reionization, which end up forming the center of the galaxy. Due to incomplete dynamical mixing during galaxy assembly, these early patterns survive to present day, resulting in a clear radial gradient in the average satellite reionization redshift, up to the virial radius of MW and M31 and beyond. In the lowest emissivity scenario, the outer satellites are reionized about 180 Myr later than the inner satellites. This delay decreases with increasing source model emissivity, or in the case of external reionization by Virgo or M31, because reionization occurs faster overall and becomes spatially quasi-uniform at the highest emissivity.

  18. Meteorological satellite accomplishments

    NASA Technical Reports Server (NTRS)

    Allison, L. J.; Arking, A.; Bandeen, W. R.; Shenk, W. E.; Wexler, R.

    1974-01-01

    The various types of meteorological satellites are enumerated. Vertical sounding, parameter extraction technique, and both macroscale and mesoscale meteorological phenomena are discussed. The heat budget of the earth-atmosphere system is considered, along with ocean surface and hydrology.

  19. Domestic Communication Satellites

    ERIC Educational Resources Information Center

    Horowitz, Andrew

    1974-01-01

    A discussion of the Federal Communications Commission's new policy on domestic satellites in light of our 1) military and economic history; 2) corporate interests; 3) citizen surveillance; and 4) media control. (HB)

  20. AUSSAT mobile satellite services

    NASA Technical Reports Server (NTRS)

    Nowland, Wayne L.; Wagg, Michael; Simpson, Daniel

    1988-01-01

    An overview of AUSSAT's planned mobile satellite system is given. The development program which is being undertaken to achieve the 1992 service date is described. Both business and technical aspects of the development program are addressed.

  1. Weather, land satellite sale

    NASA Astrophysics Data System (ADS)

    Richman, Barbara T.

    President Ronald Reagan announced on March 8 plans to sell to private industry the nation's land and meteorological remote-sensing satellites, including the responsibility for any future ocean-observing systems. According to the plan, the private firm successful in its bid to buy the five satellites would sell back to the government the data received by the satellites. The Reagan administration says the sale will save money and will put activities appropriate for commercial ventures into the commercial sector. Response to the announcement from scientists and congressmen has been anything but dulcet; one senator, in fact, charges that the Commerce Department and the corporation most likely to purchase the satellites are engaged in a ‘sweetheart deal.’

  2. Aiming a Satellite Dish.

    ERIC Educational Resources Information Center

    Zebrowski, Ernest, Jr.

    1988-01-01

    Develops a pair of equations for calculating the elevation and azimuth angles for the various satellites. Uses 3-dimensional vector difference calculations. Provides a practical example, figures, and table. (YP)

  3. Speckle imaging of satellites

    SciTech Connect

    Fitch, J.P.; Lawrence, T.W.; Goodman, D.M.; Johansson, E.M.

    1991-12-01

    We performed a series of experiments using the Air Force Optical Station`s 1.6 m telescope and a bare CCD detector to capture speckle images of various satellites. The speckle images were processed with bispectral techniques for recovering image Fourier phase as well as projection onto convex sets for recovering image Fourier magnitude from the projected autocorrelation. Results of imaging point stars and binaries are shown as a baseline assessment of our technique. We have reconstructed high quality images of numerous satellites and will show reconstructions of a very familiar satellite: the Hubble Space Telescope. To our knowledge, this is the first demonstration of the use of bare CCDs for speckle imaging of relatively bright objects such as artificial satellites. 8 refs.

  4. Speckle imaging of satellites

    SciTech Connect

    Fitch, J.P.; Lawrence, T.W.; Goodman, D.M.; Johansson, E.M.

    1991-12-01

    We performed a series of experiments using the Air Force Optical Station's 1.6 m telescope and a bare CCD detector to capture speckle images of various satellites. The speckle images were processed with bispectral techniques for recovering image Fourier phase as well as projection onto convex sets for recovering image Fourier magnitude from the projected autocorrelation. Results of imaging point stars and binaries are shown as a baseline assessment of our technique. We have reconstructed high quality images of numerous satellites and will show reconstructions of a very familiar satellite: the Hubble Space Telescope. To our knowledge, this is the first demonstration of the use of bare CCDs for speckle imaging of relatively bright objects such as artificial satellites. 8 refs.

  5. Trends In Satellite Communication

    NASA Technical Reports Server (NTRS)

    Poley, William A.; Stevens, Grady H.; Stevenson, Steven M.; Lekan, Jack; Arth, Clifford H.; Hollansworth, James E.; Miller, Edward F.

    1988-01-01

    Report assesses trends in satellite communication from present to year 2010. Examines restrictions imposed by limited spectrum resource and technology needs created by trends. Personal communications, orbiting switchboards, and videophones foreseen.

  6. Epos TCS Satellite Data

    NASA Astrophysics Data System (ADS)

    Manunta, Michele; Mandea, Mioara; Fernández-Turiel, José Luis; Stramondo, Salvatore; Wright, Tim; Walter, Thomas; Bally, Philippe; Casu, Francesco; Zeni, Giovanni; Buonanno, Sabatino; Zinno, Ivana; Tizzani, Pietro; Castaldo, Raffaele; Ostanciaux, Emilie; Diament, Michel; Hooper, Andy; Maccaferri, Francesco; Lanari, Riccardo

    2016-04-01

    TCS Satellite Data is devoted to provide Earth Observation (EO) services, transversal with respect to the large EPOS community, suitable to be used in several application scenarios. In particular, the main goal is to contribute with mature services that have already well demonstrated their effectiveness and relevance in investigating the physical processes controlling earthquakes, volcanic eruptions and unrest episodes as well as those driving tectonics and Earth surface dynamics. The TCS Satellite Data will provide two kinds of services: satellite products/services, and Value-added satellite products/services. The satellite products/services are composed of three (EPOSAR, GDM and COMET) well-identified and partly already operational elements for delivering Level 1 products. Such services will be devoted to the generation of SAR interferograms, DTM and ground displacement maps through the exploitation of different advanced EO techniques for InSAR and optical data analysis. The Value-added satellite products/services are composed of 4 elements (EPOSAR, 3D-Def, Mod and COMET) of Level 2 and 3 products. Such services integrate satellite and in situ measurements and observations to retrieve information on source mechanism, such as the geometry (spatial location, depth, volume changes) and the physical parameters of the deformation sources, through the exploitation of modelling approaches. The TCS Satellite Data will provide products in two different processing and delivery modes: 1- surveillance mode - routinely product generation; 2- on demand mode - product generation performed on demand by the user. Concerning the surveillance mode, the goal is providing continuous satellite measurements in areas of particular interest from a geophysical perspective (supersites). The objective is the detection of displacement patterns changing along time and their geophysical explanation. This is a valid approach for inter-seismic movements and volcanic unrest, post-seismic and post

  7. Satellite Applications for Public Service: Project Summaries.

    ERIC Educational Resources Information Center

    Lauffer, Sandra; And Others

    Summaries of 18 different projects involving the use of satellite communications are presented in this report, including PEACESAT Education and Communication Experiments, USP Network Satellite Communication Project, Project Satellite, Satellite Instructional Television Experiment (SITE), Appalachian Education Satellite Program, Alaska Education…

  8. Drones of the dwarf honey bee Apis florea are attracted to (2E)-9-oxodecenoic acid and (2E)-10-hydroxydecenoic acid.

    PubMed

    Nagaraja, Narayanappa; Brockmann, Axel

    2009-06-01

    The queen mandibular gland component (2E)-9-oxodecenoic acid (9-ODA) has been suggested to function as the major sex pheromone component in all honey bee species. In contrast to this hypothesis, chemical analyses showed that in the Asian dwarf honey bee species, Apis florea, a different decenoic acid, (2E)-10-hydroxydecenoic acid (10-HDA), is the major component in the mandibular gland secretion. We show here that A. florea drones are attracted to 9-ODA as well as to 10-HDA. However, 10-HDA attracted higher numbers of drones at lower dosages than 9-ODA, and also was more attractive when directly compared to 9-ODA in a dual attraction experiment. We conclude that 10-HDA has to be viewed as the major sex pheromone in A. florea. The result that both pheromone components are capable of attracting drones when presented alone was unexpected with regard to existing sex pheromone attraction experiments in honey bees.

  9. A new fluorescent enhanced probe based on (E)-9-(2-nitrovinyl)-anthracene for the detection of bisulfite anions and its practical application

    NASA Astrophysics Data System (ADS)

    Chao, Jianbin; Liu, Yuhong; Zhang, Yan; Zhang, Yongbin; Huo, Fangjun; Yin, Caixia; Wang, Yu; Qin, Liping

    2015-07-01

    A new fluorescent enhanced probe based on (E)-9-(2-nitrovinyl)-anthracene is developed, which shows high selectivity and sensitivity for the detection of bisulfite anions at Na2HPO4 citric acid buffer solutions (pH 5.0). When addition of HSO3-, the fluorescence intensity is significantly enhanced and the probe displays apparent fluorescence color changes from non-fluorescence to blue under a UV lamp illumination, the solution color also changes from yellow to colorless. The detection limit is determined to be as low as 6.30 μM. This offers another specific colorimetric and fluorescent probe for bisulfite anions detection, furthermore it is applied in detecting the level of bisulfite in sugar samples.

  10. Direct Broadcasting Satellites in Japan.

    ERIC Educational Resources Information Center

    Maeda, Jiro

    The development and use of broadcasting satellites in Japan are discussed in this paper. The paper describes the medium-scale experimental broadcasting satellite, YURI, launched by NASA in 1978, and reports that experiments with YURI in the areas of basic technologies in the broadcasting satellite system, experiments on satellite control…

  11. Satellite Technologies in the Classroom.

    ERIC Educational Resources Information Center

    Portz, Stephen M.

    1999-01-01

    Focuses on ways of using satellite imagery obtained from the Internet, to enhance classroom learning. Discusses satellite deployment; classroom applications, including infrared imagery, high-resolution photography, and global positioning satellites; and use of satellite data for hands-on activities, including cartography, city and community…

  12. Long-term treadmill exercise improves spatial memory of male APPswe/PS1dE9 mice by regulation of BDNF expression and microglia activation.

    PubMed

    Xiong, J Y; Li, S C; Sun, Y X; Zhang, X S; Dong, Z Z; Zhong, P; Sun, X R

    2015-11-01

    Increasing evidence suggests that physical activity could delay or attenuate the symptoms of Alzheimer's disease (AD). But the underlying mechanisms are still not fully understood. To investigate the effect of long-term treadmill exercise on the spatial memory of AD mice and the possible role of β-amyloid, brain-derived neurotrophic factor (BDNF) and microglia in the effect, male APPswe/PS1dE9 AD mice aged 4 months were subjected to treadmill exercise for 5 months with 6 sessions per week and gradually increased load. A Morris water maze was used to evaluate the spatial memory. Expression levels of β-amyloid, BDNF and Iba-1 (a microglia marker) in brain tissue were detected by immunohistochemistry. Sedentary AD mice and wildtype C57BL/6J mice served as controls. The results showed that 5-month treadmill exercise significantly decreased the escape latencies (P < 0.01 on the 4th day) and improved the spatial memory of the AD mice in the water maze test. Meanwhile, treadmill exercise significantly increased the number of BDNF-positive cells and decreased the ratios of activated microglia in both the cerebral cortex and the hippocampus. However, treadmill exercise did not significantly alleviate the accumulation of β-amyloid in either the cerebral cortex or the hippocampus of the AD mice (P > 0.05). The study suggested that long-term treadmill exercise could improve the spatial memory of the male APPswe/PS1dE9 AD mice. The increase in BDNF-positive cells and decrease in activated microglia might underpin the beneficial effect.

  13. Critical areas: Satellite power systems concepts

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Critical Areas are defined and discussed in the various areas pertinent to satellite power systems. The presentation is grouped into five areas (General, Space Systems, Solar Energy Conversion, Microwave Systems, and Environment/Ecology) with a sixth area (Power Relay) considered separately in an appendix. Areas for Future Consideration as critical areas are discussed in a second appendix.

  14. Design trade-offs in antijam military satellite communications

    NASA Astrophysics Data System (ADS)

    Brandon, W. T.

    1982-07-01

    Military satellite communications system technical parameters, boundary values and anti-jamming trade-offs among parameters are described and discussed. These systems, which have become essential elements of command, control and communication structures for the U.S., NATO and the Soviet Union, are characterized by such features as global connectivity of commanders and forces, and instant reconfiguration which allows a single system to support services as varied as broadcasting, point-to-point voice communication, and teletype data, for tactical, strategic or logistic users. Attention is given to the anti-jamming concept of satellite position uncertainty, in which a group of satellites functions as uplink receiver, and a single, larger satellite is used as a downlink transmitter. It is shown that, by constraining design to a finite number of satellite orbits, frequency bands and satellite and terminal designs, a practical number of about 5000 different system designs can be stipulated for further study.

  15. The dynamics of tidal tails from massive satellites

    NASA Astrophysics Data System (ADS)

    Choi, Jun-Hwan; Weinberg, Martin D.; Katz, Neal

    2007-11-01

    We investigate the dynamical mechanisms responsible for producing tidal tails from dwarf satellites using N-body simulations. We describe the essential dynamical mechanisms and morphological consequences of tail production in satellites with masses greater than 0.0001 of the host halo virial mass. We identify two important dynamical coconspirators: (1) the points where the attractive force of the host halo and satellite are balanced (X-points) do not occur at equal distances from the satellite centre or at the same equipotential value for massive satellites, breaking the morphological symmetry of the leading and trailing tails and (2) the escaped ejecta in the leading (trailing) tail continues to be decelerated (accelerated) by the satellite's gravity leading to large offsets of the ejecta orbits from the satellite orbit. The effect of the satellite's self-gravity decreases only weakly with a decreasing ratio of satellite mass to host halo mass, proportional to (Ms/Mh)1/3, demonstrating the importance of these effects over a wide range of subhalo masses. Not only will the morphology of the leading and trailing tails for massive satellites be different, but the observed radial velocities of the tails will be displaced from that of the satellite orbit; both the displacement and the maximum radial velocity is proportional to satellite mass. If the tails are assumed to follow the progenitor satellite orbits, the tails from satellites with masses greater than 0.0001 of the host halo virial mass in a spherical halo will appear to indicate a flattened halo. Therefore, a constraint on the Milky Way halo shape using tidal streams requires mass-dependent modelling. Similarly, we compute the distribution of tail orbits both in Er-r-2 space and in E-Lz space, advocated for identifying satellite stream relics. The acceleration of ejecta by a massive satellite during escape spreads the velocity distribution and obscures the signature of a well-defined `moving group' in phase

  16. High performance satellite networks

    NASA Astrophysics Data System (ADS)

    Helm, Neil R.; Edelson, Burton I.

    1997-06-01

    The high performance satellite communications networks of the future will have to be interoperable with terrestrial fiber cables. These satellite networks will evolve from narrowband analogue formats to broadband digital transmission schemes, with protocols, algorithms and transmission architectures that will segment the data into uniform cells and frames, and then transmit these data via larger and more efficient synchronous optional (SONET) and asynchronous transfer mode (ATM) networks that are being developed for the information "superhighway". These high performance satellite communications and information networks are required for modern applications, such as electronic commerce, digital libraries, medical imaging, distance learning, and the distribution of science data. In order for satellites to participate in these information superhighway networks, it is essential that they demonstrate their ability to: (1) operate seamlessly with heterogeneous architectures and applications, (2) carry data at SONET rates with the same quality of service as optical fibers, (3) qualify transmission delay as a parameter not a problem, and (4) show that satellites have several performance and economic advantages over fiber cable networks.

  17. Satellite altimeter calibration techniques

    NASA Technical Reports Server (NTRS)

    Kolenkiewicz, R.; Martin, C. F.

    1990-01-01

    This paper examines calibration techniques which can most effectively satisfy the requirements of future satellites carrying high-accuracy radar altimeters, such as the ESA ERS-1 and the NASA/CNES Topex/Poseidon satellites scheduled for launch during the next five years. The calibration accuracies and the advantages and disadvantages of the four currently proposed calibration techniques for over-water calibration are discussed: (1) a tide gauge on a tower at-sea and a nearby laser, (2) a laser and a tide gauge on an island with an offshore satellite pass and a geoid tie between the satellite ground track and the laser, (3) a tide gauge on a tower at-sea with satellite positioning from multiple lasers and a GPS, and (4) a laser and a tide gauge on a tower at-sea. Error budgets for these techniques, developed on the basis of state-of-the-art tracking systems, were found to have one sigma height uncertainties in the 2.8 to 4.9 cm range.

  18. Comparing Two Satellite Sensors

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This pair of images shows the same area of South Africa's Kruger National Park taken by different satellite sensors only minutes apart. The top image is from the Enhanced Thematic Mapper plus (ETM+) aboard Landsat 7, the latest in a long line of high-resolution remote sensing satellites begun in 1972 with the Earth Resources Technology Satellite (ERTS), later renamed Landsat-1. The bottom image was acquired by the Advanced Land Imager (ALI) aboard Earth Observer-1 (EO-1), an instrument designed to test new technologies that will continue the observations begun by the Landsat satellites. Future instruments like the ALI will be much smaller and less expensive than the ETM+, enabling NASA and the United States Geological Survey (USGS) to continue exploring the surface of the Earth. Both images above are false color composites combining short wave infrared (1.65 um), near infrared (.79 um), and green (.57 um) wavelengths as red, green, and blue, respectively. Dense vegetation appears green. The similarity of the images demonstrates the ability of the ALI to produce data that can be compared with the 29-year archive of Landsat data. Several NASA field campaigns conducted in Kruger National Park provided ground-based data needed to evaluate measurements from each of the satellite sensors. For more information, read the EO-1 fact sheet and the Landsat-7 fact sheet. Images courtesy Landsat 7 Science Team

  19. Satellite altimeter calibration techniques

    NASA Astrophysics Data System (ADS)

    Kolenkiewicz, R.; Martin, C. F.

    This paper examines calibration techniques which can most effectively satisfy the requirements of future satellites carrying high-accuracy radar altimeters, such as the ESA ERS-1 and the NASA/CNES Topex/Poseidon satellites scheduled for launch during the next five years. The calibration accuracies and the advantages and disadvantages of the four currently proposed calibration techniques for over-water calibration are discussed: (1) a tide gauge on a tower at-sea and a nearby laser, (2) a laser and a tide gauge on an island with an offshore satellite pass and a geoid tie between the satellite ground track and the laser, (3) a tide gauge on a tower at-sea with satellite positioning from multiple lasers and a GPS, and (4) a laser and a tide gauge on a tower at-sea. Error budgets for these techniques, developed on the basis of state-of-the-art tracking systems, were found to have one sigma height uncertainties in the 2.8 to 4.9 cm range.

  20. International communications via satellite

    NASA Astrophysics Data System (ADS)

    McLucas, J. L.

    The evolution of communications satellite systems is traced in terms of technical capabilities and technological advances. The Communications Act of 1962 led to the establishment of INTELSAT on an international basis in 1964. The original 19 signatory nations has grown to over 100, and over 800 ground relay stations have been built. The INTELSAT system comprises spacecraft over the Atlantic, Pacific, and Indian Oceans and handles 2/3 of the world's international electronic communications and all transoceanic television. The 1965 Early Bird satellite had a 240 two-way telephone link capacity and weighed 38 kg, while the Intelsat V satellites, of which there will be nine, have increased the capacity to 20,000 voice circuits and Intelsat VI will double the number by 1993. Increasing demand for satellite communications links is driving the design and development of space platforms for multiple missions of communications, meteorological studies, and on-board switching and data processing in excess of current multiple satellite systems.

  1. Best Practices for Operations of Satellite Constellations

    NASA Technical Reports Server (NTRS)

    Howard, Joseph; Oza, Dipak; Smith, Danford S.

    2006-01-01

    This paper presents the best practices used by several commercial and government operators of satellite constellations. These best practices were identified through a series of seminars and discussions held at NASA Goddard Space Flight Center (GSFC). The best practices are arrived through many years of experience and improvements made in the operations procedures and the operational systems with the primary drivers as mission safety and cost effectiveness. This paper discusses the operational aspects associated with how different organizations manage complexities of constellation operations. For the purposes of this paper, satellite constellations are groups of similar spacecraft with more than one spacecraft needed to fully accomplish the constellation's mission

  2. Satellite failures revisited

    NASA Astrophysics Data System (ADS)

    Balcerak, Ernie

    2012-12-01

    In January 1994, the two geostationary satellites known as Anik-E1 and Anik-E2, operated by Telesat Canada, failed one after the other within 9 hours, leaving many northern Canadian communities without television and data services. The outage, which shut down much of the country's broadcast television for hours and cost Telesat Canada more than $15 million, generated significant media attention. Lam et al. used publicly available records to revisit the event; they looked at failure details, media coverage, recovery effort, and cost. They also used satellite and ground data to determine the precise causes of those satellite failures. The researchers traced the entire space weather event from conditions on the Sun through the interplanetary medium to the particle environment in geostationary orbit.

  3. Artificial gravity experiment satellites

    NASA Astrophysics Data System (ADS)

    Harada, Tadashi

    1992-07-01

    An overview of the conceptual study of an artificial gravity experiment satellite based on the assumption of a launch by the H-2 launch vehicle with a target launch date in the Year 2000 is presented. While many satellites provided with artificial gravity have been reported in relation to a manned Mars exploration spacecraft mission, the review has been conducted on missions and test subjects only for experimental purposes. Mission requirements were determined based on the results of reviews on the mission, test subjects, and model missions. The system baseline and development plan were based on the results of a study on conceptual structure and scale of the system, including measures to generate artificial gravity. Approximate scale of the system and arm length, mission orbit, visibility of the operation orbit from ground stations in Japan, and satellite attitude on the mission orbit are outlined.

  4. The Clementine satellite

    SciTech Connect

    Not Available

    1994-06-01

    The first US satellite to the Moon in more than two decades was launched from Vandenberg Air Force Base (Santa Barbara County), California, on January 25, 1994. The satellite was named Clementine because it carried only enough fuel to complete its mission before it was [open quotes]lost and gone forever.[close quotes] The Clementine satellite tested 23 advanced technologies during its mission for the Ballistic Missile Defense Organization. In fulfilling its scientific goals, Clementine provided a wealth of information relevant to the mineralogy of the lunar surface. Using six on-board cameras designed and built at the Laboratory, Clementine mapped the entire surface of the Moon at resolutions never before attained. Clementine also provided range data that will be used to construct a relief map of the lunar surface.

  5. Brazilian Small Satellites

    NASA Astrophysics Data System (ADS)

    Carvalho, Himilcon

    Brazilian experience with micro scientific satellites began in 1995 with the SACI project that comprised 2 scientific satellites that carried onboard experiments from Brazil, Japan and US. The first one failed after launch (1998) and the second was lost during the second launch attempt of the Brazilian national launcher, VLS, in1999. Started by 1997, the French-Brazilian Microsatellite Project comprised a set of 9 experiments from French and Brazilian scientists. The project was terminated by the French side in 2002. Currently, there are two ongoing science projects, MIRAX (devoted to X-Ray astronomy) and EQUARS (to study the higher atmosphere). These projects include experiments from US, Netherlands, Japan, Canada, and Brazil, with launch scheduled to 2011 or 2012. This paper presents a brief summary of the history of the development of these satellites along with some highlights on the Brazilian Space Program.

  6. AVS on satellite

    NASA Astrophysics Data System (ADS)

    Zhao, Haiwu; Wang, Guozhong; Hou, Gang

    2005-07-01

    AVS is a new digital audio-video coding standard established by China. AVS will be used in digital TV broadcasting and next general optical disk. AVS adopted many digital audio-video coding techniques developed by Chinese company and universities in recent years, it has very low complexity compared to H.264, and AVS will charge very low royalty fee through one-step license including all AVS tools. So AVS is a good and competitive candidate for Chinese DTV and next generation optical disk. In addition, Chinese government has published a plan for satellite TV signal directly to home(DTH) and a telecommunication satellite named as SINO 2 will be launched in 2006. AVS will be also one of the best hopeful candidates of audio-video coding standard on satellite signal transmission.

  7. ESA's satellite communications programme

    NASA Astrophysics Data System (ADS)

    Bartholome, P.

    1985-02-01

    The developmental history, current status, and future plans of the ESA satellite-communications programs are discussed in a general survey and illustrated with network diagrams and maps. Consideration is given to the parallel development of national and European direct-broadcast systems and telecommunications networks, the position of the European space and electronics industries in the growing world market, the impact of technological improvements (both in satellite systems and in ground-based networks), and the technological and commercial advantages of integrated space-terrestrial networks. The needs for a European definition of the precise national and international roles of satellite communications, for maximum speed in implementing such decisions (before the technology becomes obsolete), and for increased cooperation and standardization to assure European equipment manufacturers a reasonable share of the market are stressed.

  8. Uranus satellites - Surface properties

    NASA Technical Reports Server (NTRS)

    Veverka, J.; Brown, R. H.; Bell, Jeffrey F.

    1991-01-01

    The post-Voyager knowledge of the photometric, colorimetric, spectral, and thermal properties of the Uranian satellites is reviewed, focusing on such fundamental physical properties as albedo, color, and surface texture. While albedo variations of at least a factor of 2 exist, color differences are almost absent (Miranda) or subdued (Oberon). In the case of Titania, the strong opposition effect reported by ground-based observers was confirmed by Voyager. Voyager did not observe the opposition parts of the phase curves of the other satellites. Voyager thermal observations of Ariel and Miranda suggest that both have highly porous regoliths, thermophysically similar to those of Jupiter's icy satellites. At the time of the flyby (south pole facing the sun), maximum surface temperatures reached or exceeded 85 K, but nighttime polar temperatures are predicted to drop to 20 to 30 K because each pole spends about 40 yr in darkness. Ground-based spectroscopy identified water ice as an important surface constituent.

  9. NEAs' Satellites Under Close Encounters with Earth

    NASA Astrophysics Data System (ADS)

    Araujo, Rosana; Winter, O. C.

    2012-10-01

    In the present work we took into account the gravitational effects experienced by a NEA (Near-Earth Asteroid), during a close encounter with Earth, in order to estimate the stability regions of NEAs' satellites as a function of the encounter conditions and for different primary-satellite mass ratio values. Initially, the methodology consisted on numerically simulating a system composed by the Sun, the planets of the Solar System, and samples of NEAs belonging to the groups Apollo, Atens and Amor, for a period of 10 Myr. All encounters with Earth closer than 100 Earth's radius were registered. The next step consisted on simulating all those registered close encounters considering the Earth, the asteroid that perform the close encounter, and a cloud of satellites around the asteroid. We considered no-interacting satellites with circular orbits, random values for the inclination, longitude of the ascending node and true anomaly, and with radial distribution going from 0.024 to 0.4 Hill's radius of the asteroid. The largest radial distance for which all the satellites survive (no collision or ejection) is defined as the critical radius. We present a statistical analysis of the registered encounters and the critical radius found, defining the stable regions as a function of the impact parameter - d, and of the relative velocity - V. For the case of massless satellites, we found that all satellites survived for encounters with d>0.3 Earth Hill's radius. For impact parameter d<0.13 Earth Hill's radius, we found that particles with radial distance greater than 0.24 Hill's radius of the asteroid, are unstable, for any relative velocity. The results for the other considered cases will be presented and discussed. We also discuss the implications of the regions found, specially in the NEAs-binary scenarios.

  10. Navigation and control of large satellite formations

    NASA Astrophysics Data System (ADS)

    Bamford, William Alfred, Jr.

    In recent years, there has been substantial interest in autonomous satellite formations, driven by the new technologies that enable smaller and cheaper spacecraft. Formation flying allows for mission designs, such as stereoscopic imaging, that are impractical or impossible for a single satellite. Much of the current work focuses upon small formations, which can be defined as four or less satellites in a relatively tight grouping. Next generation formations may be composed of more satellites spanning greater spatial distances. The large formation problem becomes more difficult for several reasons, including an increased amount of communication required between the satellites, and orbit perturbations, which become more important as the formation size grows. The purpose of this dissertation is to examine formation flying for large formations, and determine whether or not generalizations can be made linking the large and small formation regimes. In order to model formations with many satellites, a simulation environment was constructed in which different observers, controllers, and formation architectures can be modelled. This dissertation focuses on a decentralized control scheme, but the software is general enough to accommodate a variety of control architectures. Validation of the large formation models is accomplished by initially modelling only a pair of satellites and comparing the results against those found in the literature. As a demonstration of the theoretical results, a real-time, closed-loop, hardware-in-the-loop simulation was constructed using GPS receivers as the measurement source. A large constellation, real-tune simulation system was developed that utilized the Internet to connect simulation equipment from research centers in different locations.

  11. Relationship between ubiquilin-1 and BACE1 in human Alzheimer's disease and APdE9 transgenic mouse brain and cell-based models.

    PubMed

    Natunen, Teemu; Takalo, Mari; Kemppainen, Susanna; Leskelä, Stina; Marttinen, Mikael; Kurkinen, Kaisa M A; Pursiheimo, Juha-Pekka; Sarajärvi, Timo; Viswanathan, Jayashree; Gabbouj, Sami; Solje, Eino; Tahvanainen, Eveliina; Pirttimäki, Tiina; Kurki, Mitja; Paananen, Jussi; Rauramaa, Tuomas; Miettinen, Pasi; Mäkinen, Petra; Leinonen, Ville; Soininen, Hilkka; Airenne, Kari; Tanzi, Rudolph E; Tanila, Heikki; Haapasalo, Annakaisa; Hiltunen, Mikko

    2016-01-01

    Accumulation of β-amyloid (Aβ) and phosphorylated tau in the brain are central events underlying Alzheimer's disease (AD) pathogenesis. Aβ is generated from amyloid precursor protein (APP) by β-site APP-cleaving enzyme 1 (BACE1) and γ-secretase-mediated cleavages. Ubiquilin-1, a ubiquitin-like protein, genetically associates with AD and affects APP trafficking, processing and degradation. Here, we have investigated ubiquilin-1 expression in human brain in relation to AD-related neurofibrillary pathology and the effects of ubiquilin-1 overexpression on BACE1, tau, neuroinflammation, and neuronal viability in vitro in co-cultures of mouse embryonic primary cortical neurons and microglial cells under acute neuroinflammation as well as neuronal cell lines, and in vivo in the brain of APdE9 transgenic mice at the early phase of the development of Aβ pathology. Ubiquilin-1 expression was decreased in human temporal cortex in relation to the early stages of AD-related neurofibrillary pathology (Braak stages 0-II vs. III-IV). There was a trend towards a positive correlation between ubiquilin-1 and BACE1 protein levels. Consistent with this, ubiquilin-1 overexpression in the neuron-microglia co-cultures with or without the induction of neuroinflammation resulted in a significant increase in endogenously expressed BACE1 levels. Sustained ubiquilin-1 overexpression in the brain of APdE9 mice resulted in a moderate, but insignificant increase in endogenous BACE1 levels and activity, coinciding with increased levels of soluble Aβ40 and Aβ42. BACE1 levels were also significantly increased in neuronal cells co-overexpressing ubiquilin-1 and BACE1. Ubiquilin-1 overexpression led to the stabilization of BACE1 protein levels, potentially through a mechanism involving decreased degradation in the lysosomal compartment. Ubiquilin-1 overexpression did not significantly affect the neuroinflammation response, but decreased neuronal viability in the neuron-microglia co

  12. ON ASYMMETRIC DISTRIBUTIONS OF SATELLITE GALAXIES

    SciTech Connect

    Bowden, A.; Evans, N. W.; Belokurov, V.

    2014-10-01

    We demonstrate that the asymmetric distribution of M31 satellites cannot be produced by tides from the Milky Way as such effects are too weak. However, loosely bound associations and groups of satellites can fall into larger halos and give rise to asymmetries. We compute the survival times for such associations. We prove that the survival time is always shortest in Keplerian potentials, and can be ∼3 times longer in logarithmic potentials. We provide an analytical formula for the dispersal time in terms of the size and velocity dispersion of the infalling structure. We show that, if an association of ∼10 dwarfs fell into the M31 halo, its present aspect would be that of an asymmetric disk of satellites. We also discuss the case of cold substructure in the Andromeda II and Ursa Minor dwarfs.

  13. SMSK performance in nonlinear satellite channels

    NASA Astrophysics Data System (ADS)

    Rasmussen, S.; Schreitmueller, W.

    Serial Minimum Shift-Keying (SMSK) has been recently recommended for satellite applications owing to certain favourable features inherent in the modulation technique, on the one hand, and in the serial implementation, on the other hand. In this paper the performance of SMSK in nonlinear satellite channels is analyzed and compared with that of MSK and QPSK. Emphasis is on the discussion of certain aspects crucial for SMSK, e.g. serial implementation, narrowband transmission, group delay sensitivity and equalization. It is found that (S)MSK, i.e. MSK and SMSK, is not very well suited for satellite applications maximizing bandwidth efficiency. Thus alternative CPM-schemes using other modulation formats are considered as well and possible improvements relative to (S)MSK achievable with simple MSK type receivers are discussed.

  14. Satellites For Sale

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Astronaut Dale A. Gardner, having just completed the major portion of his second extravehicular activity (EVA) period in three days, holds up a 'For Sale' sign refering to the two satellites, Palapa B-2 and Westar 6 that they retrieved from orbit after their Payload Assist Modules (PAM) failed to fire. Astronaut Joseph P. Allen IV, who also participated in the two EVAs, is reflected in Gardner's helmet visor. A portion of each of two recovered satellites is in the lower right corner, with Westar 6 nearer Discovery's aft.

  15. Satellite altitude determination uncertainties

    NASA Technical Reports Server (NTRS)

    Siry, J. W.

    1972-01-01

    Satellite altitude determination uncertainties will be discussed from the standpoint of the GEOS-C satellite, from the longer range viewpoint afforded by the Geopause concept. Data are focused on methods for short-arc tracking which are essentially geometric in nature. One uses combinations of lasers and collocated cameras. The other method relies only on lasers, using three or more to obtain the position fix. Two typical locales are looked at, the Caribbean area, and a region associated with tracking sites at Goddard, Bermuda and Canada which encompasses a portion of the Gulf Stream in which meanders develop.

  16. Satellite Laser Ranging operations

    NASA Technical Reports Server (NTRS)

    Pearlman, Michael R.

    1994-01-01

    Satellite Laser Ranging (SLR) is currently providing precision orbit determination for measurements of: 1) Ocean surface topography from satellite borne radar altimetry, 2) Spatial and temporal variations of the gravity field, 3) Earth and ocean tides, 4) Plate tectonic and regional deformation, 5) Post-glacial uplift and subsidence, 6) Variations in the Earth's center-of-mass, and 7) Variations in Earth rotation. SLR also supports specialized programs in time transfer and classical geodetic positioning, and will soon provide precision ranging to support experiments in relativity.

  17. Geodynamics from satellites

    NASA Technical Reports Server (NTRS)

    Kaula, W. M.

    1979-01-01

    The NASA Geodynamics Program is developing a variety of techniques in support of national programs in geodynamics, geomagnetics and earthquake hazard reduction. Global tectonics are to be observed by satellite laser tracking and radio interferometry, which will be used to measure the movements of extended (greater than 200 km) regions to an accuracy of 3 cm, while for shorter distances, lasers enable a more rapid measuring of regional strain accumulation patterns than ground systems. The techniques of Doppler tracking between two satellites to measure the gravity field over the ocean is also under NASA study

  18. Satellite communications system 'Tyulpan'

    NASA Astrophysics Data System (ADS)

    Tchuyan, R. K.; Tarasov, E. V.; Belousov, A. P.; Balyk, V. M.; Kovtunenko, V. M.; Morozov, V. A.; Andreev, V. A.; v'yunenko, K. A.

    1993-10-01

    A concept of the satellite communication system called 'Tyulpan' (because or its tulip-resembling shape) is considered. This conception envisages the use of six satellites-retranslators installed on high-latitude elliptic orbits. Such a system can provide the communication for mean- and high-latitude region of Europe, Asia, and America. For the communication, super small ground stations of 0.4 m in diameter can be used. In the development of system conception, the already existing technical solutions and possibility of conversion or existing installations of military destination were taken into account. Therefore, the system considered can be realized at the earliest possible date.

  19. Declassified intelligence satellite photographs

    USGS Publications Warehouse

    ,

    1998-01-01

    Recently declassified photographs from spy satellites are an important addition to the record of the Earth?s land surface held by the U.S. Geological Survey (USGS). More than 800,000 high-resolution photos taken between 1959 through 1972 were made available by Executive Order of the President. The collection is held at the USGS EROS Data Center, near Sioux Falls, S. Dak., and are offered for public sale. For some purposes in earth science studies, these photos extend the record of changes in the land surface another decade back in time from the advent of the Landsat earth-observing satellite program.

  20. Satellite laser ranging

    NASA Astrophysics Data System (ADS)

    Osorio, J. P.

    1992-03-01

    Laser ranging to satellites is one of the most precise methods for positio ning on the surface of the Earth. Reference is made to the need for precise posi tioning and to the improvement brought by the use of space techniques. Satellite Laser Ranging system is then described and in view of the high precision of the results derived from its measurements comments are made to some of the more important applications: high precision networks tectonic plate motion polar motion and earth''s rotation. Finally plans for system improvement in the near future are also presented.

  1. CEOS Committee on Earth Observations Satellites consolidated report, 1992

    NASA Astrophysics Data System (ADS)

    1992-11-01

    A concise overview of the committee on Earth Observations Satellites (CEOS) and its Working Groups, covering the history and purpose of the Committee and its accomplishments to date are provided. The report will be updated annually before each Plenary meeting, and as developments in the Working Groups warrant. The committee on Earth Observations Satellites (originally named the International Earth Observations Satellite committee, IEOS) was treated in 1984, in response to a recommendation from the Economic Summit of Industrialized Nations Working Group on Growth, Technology, and Employment's Panel of Experts on Satellite Remote Sensing. This group recognized the multidisciplinary nature of satellite Earth observations, and the value of coordinating across all proposed missions. Thus, CEOS combined the previously existing groups for coordination on Ocean Remote-Sensing Satellites (CORSS) and coordination on Land Remote-Sensing Satellites (CLRSS), and established a broad framework for coordination across all spaceborne Earth observations missions. The first three LEOS Plenary meetings focused on treating and guiding the Working Groups deemed necessary to carry out the objectives of the CEOS members. After the third meeting, it was agreed that a more active orientation was required by the Plenary, and additional issues were brought before the group at the fourth meeting. At the fifth Plenary, international scientific programs and relevant intergovernmental organizations accepted invitations and participated as affiliate members of CEOS. This enabled progress toward integrating satellite data users' requirements into the CEOS process. Data exchange principles for global change research were also adopted. An interim CEOS Plenary meeting was held in April 1992, in preparation for the United Nations Conference on Environment and Development (UNCED). Brief encapsulations of the Plenary sessions immediately follow the Terms of Reference that govern the activities of CEOS as

  2. CEOS Committee on Earth Observations Satellites Consolidated Report, 1992

    NASA Technical Reports Server (NTRS)

    1992-01-01

    A concise overview of the committee on Earth Observations Satellites (CEOS) and its Working Groups, covering the history and purpose of the Committee and its accomplishments to date are provided. The report will be updated annually before each Plenary meeting, and as developments in the Working Groups warrant. The committee on Earth Observations Satellites (originally named the International Earth Observations Satellite committee, IEOS) was treated in 1984, in response to a recommendation from the Economic Summit of Industrialized Nations Working Group on Growth, Technology, and Employment's Panel of Experts on Satellite Remote Sensing. This group recognized the multidisciplinary nature of satellite Earth observations, and the value of coordinating across all proposed missions. Thus, CEOS combined the previously existing groups for coordination on Ocean Remote-Sensing Satellites (CORSS) and coordination on Land Remote-Sensing Satellites (CLRSS), and established a broad framework for coordination across all spaceborne Earth observations missions. The first three LEOS Plenary meetings focused on treating and guiding the Working Groups deemed necessary to carry out the objectives of the CEOS members. After the third meeting, it was agreed that a more active orientation was required by the Plenary, and additional issues were brought before the group at the fourth meeting. At the fifth Plenary, international scientific programs and relevant intergovernmental organizations accepted invitations and participated as affiliate members of CEOS. This enabled progress toward integrating satellite data users' requirements into the CEOS process. Data exchange principles for global change research were also adopted. An interim CEOS Plenary meeting was held in April 1992, in preparation for the United Nations Conference on Environment and Development (UNCED). Brief encapsulations of the Plenary sessions immediately follow the Terms of Reference that govern the activities of CEOS as

  3. The Impact of Bdnf Gene Deficiency to the Memory Impairment and Brain Pathology of APPswe/PS1dE9 Mouse Model of Alzheimer’s Disease

    PubMed Central

    Rantamäki, Tomi; Kemppainen, Susanna; Autio, Henri; Stavén, Saara; Koivisto, Hennariikka; Kojima, Masami; Antila, Hanna; Miettinen, Pasi O.; Kärkkäinen, Elisa; Karpova, Nina; Vesa, Liisa; Lindemann, Lothar; Hoener, Marius C.; Tanila, Heikki; Castrén, Eero

    2013-01-01

    Brain-derived neurotrophic factor (BDNF) importantly regulates learning and memory and supports the survival of injured neurons. Reduced BDNF levels have been detected in the brains of Alzheimer’s disease (AD) patients but the exact role of BDNF in the pathophysiology of the disorder remains obscure. We have recently shown that reduced signaling of BDNF receptor TrkB aggravates memory impairment in APPswe/PS1dE9 (APdE9) mice, a model of AD. The present study examined the influence of Bdnf gene deficiency (heterozygous knockout) on spatial learning, spontaneous exploratory activity and motor coordination/balance in middle-aged male and female APdE9 mice. We also studied brain BDNF protein levels in APdE9 mice in different ages showing progressive amyloid pathology. Both APdE9 and Bdnf mutations impaired spatial learning in males and showed a similar trend in females. Importantly, the effect was additive, so that double mutant mice performed the worst. However, APdE9 and Bdnf mutations influenced spontaneous locomotion in contrasting ways, such that locomotor hyperactivity observed in APdE9 mice was normalized by Bdnf deficiency. Obesity associated with Bdnf deficiency did not account for the reduced hyperactivity in double mutant mice. Bdnf deficiency did not alter amyloid plaque formation in APdE9 mice. Before plaque formation (3 months), BDNF protein levels where either reduced (female) or unaltered (male) in the APdE9 mouse cortex. Unexpectedly, this was followed by an age-dependent increase in mature BDNF protein. Bdnf mRNA and phospho-TrkB levels remained unaltered in the cortical tissue samples of middle-aged APdE9 mice. Immunohistological studies revealed increased BDNF immunoreactivity around amyloid plaques indicating that the plaques may sequester BDNF protein and prevent it from activating TrkB. If similar BDNF accumulation happens in human AD brains, it would suggest that functional BDNF levels in the AD brains are even lower than reported, which could

  4. The American Satellite Company (ASC) satellite deployed from payload bay

    NASA Technical Reports Server (NTRS)

    1985-01-01

    The American Satellite Company (ASC) communications satellite is deployed from the payload bay of the Shuttle Discovery. A portion of the cloudy surface of the earth can be seen to the left of the frame.

  5. Satellite orbit determination and gravity field recovery from satellite-to-satellite tracking

    NASA Astrophysics Data System (ADS)

    Wakker, K. F.; Ambrosius, B. A. C.; Leenman, H.

    1989-07-01

    Studies on satellite-to-satellite tracking (SST) with POPSAT (a geodetic satellite concept) and a ERS-class (Earth observation) satellite, a Satellite-to-Satellite Tracking (SST) gravity mission, and precise gravity field determination methods and mission requirements are reported. The first two studies primarily address the application of SST between the high altitude POPSAT and an ERS-class or GRM (Geopotential Research Mission) satellite to the orbit determination of the latter two satellites. Activities focussed on the determination of the tracking coverage of the lower altitude satellite by ground based tracking systems and by POPSAT, orbit determination error analysis and the determination of the surface forces acting on GRM. The third study surveys principles of SST, uncertainties of existing drag models, effects of direct luni-solar attraction and tides on orbit and the gravity gradient observable. Detailed ARISTOTELES (which replaced POPSAT) orbit determination error analyses were performed for various ground based tracking networks.

  6. 76 FR 57923 - Establishment of Rules and Policies for the Satellite Digital Audio Radio Service in the 2310...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-19

    ....144(e)(3), 25.144(e)(8), 25.144(e)(9), 25.263(b) and 25.263(c), published at 75 FR 45058, August 2... (SDARS) Second Report and Order (FCC 10-82; IB Docket No. 95-91), 75 FR 45058, August 2, 2010. Synopsis... COMMISSION 47 CFR Part 25 Establishment of Rules and Policies for the Satellite Digital Audio Radio...

  7. Activation of nicotinic α(7) acetylcholine receptor enhances long term potentation in wild type mice but not in APP(swe)/PS1ΔE9 mice.

    PubMed

    Söderman, Andreas; Mikkelsen, Jens D; West, Mark J; Christensen, Ditte Z; Jensen, Morten S

    2011-01-10

    Amyloid β (Aβ) plays a central role in Alzheimer's disease (AD) and binds to the nicotinic α(7) receptor (α(7) nAChR). Little is known about the degree to which the binding of Aβ to the α(7) nAChR influences the role of this receptor in long-term potentiation (LTP), however. We have studied the effect of the partial α(7) nAChR agonist SSR180711 on hippocampal slice preparations from normal wild type (Wt) and APP(swe)/PS1ΔE9 transgenic (Tg) mice. In the hippocampal slices from the 6 months old Wt mice, the application of both nicotine (5μM) and SSR180711 (300nM) resulted in a significant enhancement of LTP expressed in area CA1. However, in the Tg mice the application of SSR180711 did not result in an increase in LTP beyond control levels. The amount of binding of the α(7) nAChR ligand 125-I-α-bungarotoxin was not different between in Tg and Wt mice. These findings indicate that the α(7) nAChR is functionally blocked in the hippocampal neurons, downstream of the α(7) nAChR, and that this is likely due to an interaction between the receptor and Aβ, which leads to changes in LTP.

  8. L- and S-endoglin differentially modulate TGFbeta1 signaling mediated by ALK1 and ALK5 in L6E9 myoblasts.

    PubMed

    Velasco, Soraya; Alvarez-Muñoz, Patricia; Pericacho, Miguel; Dijke, Peter Ten; Bernabéu, Carmelo; López-Novoa, José M; Rodríguez-Barbero, Alicia

    2008-03-15

    TGFbeta regulates cellular processes by binding to type I and type II TGFbeta receptors (TbetaRI and TbetaRII, respectively). In addition to these signaling receptors, endoglin is an accessory TGFbeta receptor that regulates TGFbeta signaling. Although there are two different alternatively spliced isoforms of endoglin, L-endoglin (L, long) and S-endoglin (S, short), little is known about the effects of S-endoglin isoform on TGFbeta signaling. Here, we have analyzed the TGFbeta1 signaling pathways and the effects of L- and S-endoglin in endoglin-deficient L6E9 cells. We found that TGFbeta activates two distinct TbetaRI-Smad signaling pathways: ALK1-Smad1-Id1 and ALK5-Smad2-PAI1, in these cells. Interestingly, L-endoglin enhanced the ALK1-Id1 pathway, while S-endoglin promoted the ALK5-PAI1 route. These effects on signaling are supported by biological effects on TGFbeta1-induced collagen I expression and inhibition of cell proliferation. Thus, while L-endoglin decreased TGFbeta1-induced collagen I and CTGF expression and increased TGFbeta1-induced proliferation, S-endoglin strongly increased TGFbeta1-induced collagen I and CTGF expression, and reduced TGFbeta1-induced cell proliferation.

  9. Outstanding Phenotypic Differences in the Profile of Amyloid-β between Tg2576 and APPswe/PS1dE9 Transgenic Mouse Models of Alzheimer's Disease.

    PubMed

    Allué, José Antonio; Sarasa, Leticia; Izco, María; Pérez-Grijalba, Virginia; Fandos, Noelia; Pascual-Lucas, María; Ogueta, Samuel; Pesini, Pedro; Sarasa, Manuel

    2016-05-30

    APPswe/PS1dE9 and Tg2576 are very common transgenic mouse models of Alzheimer's disease (AD), used in many laboratories as tools to research the mechanistic process leading to the disease. In order to augment our knowledge about the amyloid-β (Aβ) isoforms present in both transgenic mouse models, we have developed two chromatographic methods, one acidic and the other basic, for the characterization of the Aβ species produced in the brains of the two transgenic mouse models. After immunoprecipitation and micro-liquid chromatography-electrospray ionization mass spectrometry/mass spectrometry, 10 species of Aβ, surprisingly all of human origin, were detected in the brain of Tg2576 mouse, whereas 39 species, of both murine and human origin, were detected in the brain of the APP/PS1 mouse. To the best of our knowledge, this is the first study showing the identification of such a high number of Aβ species in the brain of the APP/PS1 transgenic mouse, whereas, in contrast, a much lower number of Aβ species were identified in the Tg2576 mouse. Therefore, this study brings to light a relevant phenotypic difference between these two popular mice models of AD. PMID:27258422

  10. An anti-pyroglutamate-3 Aβ vaccine reduces plaques and improves cognition in APPswe/PS1ΔE9 mice.

    PubMed

    Frost, Jeffrey L; Liu, Bin; Rahfeld, Jens-Ulrich; Kleinschmidt, Martin; O'Nuallain, Brian; Le, Kevin X; Lues, Inge; Caldarone, Barbara J; Schilling, Stephan; Demuth, Hans-Ulrich; Lemere, Cynthia A

    2015-12-01

    Pyroglutamate-3 amyloid-beta (pGlu-3 Aβ) is an N-terminally truncated Aβ isoform likely playing a decisive role in Alzheimer's disease pathogenesis. Here, we describe a prophylactic passive immunization study in APPswe/PS1ΔE9 mice using a novel pGlu-3 Aβ immunoglobulin G1 (IgG1) monoclonal antibody, 07/1 (150 and 500 μg, intraperitoneal, weekly) and compare its efficacy with a general Aβ IgG1 monoclonal antibody, 3A1 (200 μg, intraperitoneal, weekly) as a positive control. After 28 weeks of treatment, plaque burden was reduced and cognitive performance of 07/1-immunized Tg mice, especially at the higher dose, was normalized to wild-type levels in 2 hippocampal-dependent tests and partially spared compared with phosphate-buffered saline-treated Tg mice. Mice that received 3A1 had reduced plaque burden but showed no cognitive benefit. In contrast with 3A1, treatment with 07/1 did not increase the concentration of Aβ in plasma, suggesting different modes of Aβ plaque clearance. In conclusion, early selective targeting of pGlu-3 Aβ by immunotherapy may be effective in lowering cerebral Aβ plaque burden and preventing cognitive decline in the clinical setting. Targeting this pathologically modified form of Aβ thereby is unlikely to interfere with potential physiologic function(s) of Aβ that have been proposed. PMID:26453001

  11. Mechanisms and effects of curcumin on spatial learning and memory improvement in APPswe/PS1dE9 mice.

    PubMed

    Wang, Pengwen; Su, Caixin; Li, Ruisheng; Wang, Hong; Ren, Ying; Sun, Haiyun; Yang, Jinduo; Sun, Jianning; Shi, Jing; Tian, Jinzhou; Jiang, Shucui

    2014-02-01

    Evidence suggests that curcumin, the phytochemical agent in the spice turmeric, might be a potential therapy for Alzheimer's disease (AD). Its antioxidant, anti-inflammatory properties have been investigated extensively. Studies have also shown that curcumin can reduce amyloid pathology in AD. The underlying mechanism, however, is complex and is still being explored. In this study, we used the APPswe/PS1dE9 double transgenic mice, an AD model, to investigate the effects and mechanisms of curcumin in the prevention and treatment of AD. The water maze test indicated that curcumin can improve spatial learning and memory ability in mice. Immunohistochemical staining and Western blot analysis were used to test major proteins in β-amyloid aggregation, β-amyloid production, and β-amyloid clearance. Data showed that, 3 months after administration, curcumin treatment reduced Aβ40 , Aβ42 , and aggregation of Aβ-derived diffusible ligands in the mouse hippocampal CA1 area; reduced the expression of the γ-secretase component presenilin-2; and increased the expression of β-amyloid-degrading enzymes, including insulin-degrading enzymes and neprilysin. This evidence suggests that curcumin, as a potential AD therapeutic method, can reduce β-amyloid pathological aggregation, possibly through mechanisms that prevent its production by inhibiting presenilin-2 and/or by accelerating its clearance by increasing degrading enzymes such as insulin-degrading enzyme and neprilysin.

  12. Behavioral abnormalities in APPSwe/PS1dE9 mouse model of AD-like pathology: comparative analysis across multiple behavioral domains.

    PubMed

    Janus, Christopher; Flores, Abigail Y; Xu, Guilian; Borchelt, David R

    2015-09-01

    Alzheimer's disease (AD) is characterized by dysfunction in cognitive and noncognitive domains with clinical diagnosis based on multiple neuropsychological tests. Here, we evaluated cognitive and noncognitive behaviors in 2 age cohorts (8 and 14 months at the start of the study) of APPSwe/PS1dE9 transgenic mice that model AD-like amyloidosis. We used a battery of tests that included fear-conditioned context and tone memories, swimming activity, and orientation to a proximal cue in a visible platform water maze test and burrowing and nest building activity. To compare the performance of mice across all tests, we used z-score normalization of data. The analyses revealed that the behavior of the transgenic mice was significantly compromised in cognitive as well as in noncognitive domains. Combining scores across multiple behavioral tests produced an integrated index characterizing the overall phenotypic abnormality in this model of AD-like amyloidosis. Assessing multiple behavioral domains provides a broader view of the breadth of impairments in multiple behavioral systems. Greater implementation of such approaches could enable reliable and clinically predictive evaluation of therapeutics in mouse models of amyloidosis.

  13. Planes of satellite galaxies and the cosmic web

    NASA Astrophysics Data System (ADS)

    Libeskind, Noam I.; Hoffman, Yehuda; Tully, R. Brent; Courtois, Helene M.; Pomarède, Daniel; Gottlöber, Stefan; Steinmetz, Matthias

    2015-09-01

    Recent observational studies have demonstrated that the majority of satellite galaxies tend to orbit their hosts on highly flattened, vast, possibly corotating planes. Two nearly parallel planes of satellites have been confirmed around the M31 galaxy and around the Centaurus A galaxy, while the Milky Way also sports a plane of satellites. It has been argued that such an alignment of satellites on vast planes is unexpected in the standard Λ cold dark matter (ΛCDM) model of cosmology if not even in contradiction to its generic predictions. Guided by ΛCDM numerical simulations, which suggest that satellites are channelled towards hosts along the axis of the slowest collapse as dictated by the ambient velocity shear tensor, we re-examine the planes of local satellites systems within the framework of the local shear tensor derived from the Cosmicflows-2 data set. The analysis reveals that the Local Group and Centaurus A reside in a filament stretched by the Virgo cluster and compressed by the expansion of the Local Void. Four out of five thin planes of satellite galaxies are indeed closely aligned with the axis of compression induced by the Local Void. Being the less massive system, the moderate misalignment of the Milky Way's satellite plane can likely be ascribed to its greater susceptibility to tidal torques, as suggested by numerical simulations. The alignment of satellite systems in the local Universe with the ambient shear field is thus in general agreement with predictions of the ΛCDM model.

  14. Experimental Satellite Quantum Communications.

    PubMed

    Vallone, Giuseppe; Bacco, Davide; Dequal, Daniele; Gaiarin, Simone; Luceri, Vincenza; Bianco, Giuseppe; Villoresi, Paolo

    2015-07-24

    Quantum communication (QC), namely, the faithful transmission of generic quantum states, is a key ingredient of quantum information science. Here we demonstrate QC with polarization encoding from space to ground by exploiting satellite corner cube retroreflectors as quantum transmitters in orbit and the Matera Laser Ranging Observatory of the Italian Space Agency in Matera, Italy, as a quantum receiver. The quantum bit error ratio (QBER) has been kept steadily low to a level suitable for several quantum information protocols, as the violation of Bell inequalities or quantum key distribution (QKD). Indeed, by taking data from different satellites, we demonstrate an average value of QBER=4.6% for a total link duration of 85 s. The mean photon number per pulse μ_{sat} leaving the satellites was estimated to be of the order of one. In addition, we propose a fully operational satellite QKD system by exploiting our communication scheme with orbiting retroreflectors equipped with a modulator, a very compact payload. Our scheme paves the way toward the implementation of a QC worldwide network leveraging existing receivers. PMID:26252672

  15. Solar wind monitor satellite

    SciTech Connect

    Kappenman, J.G. ); Albertson, V.D. ); Damsk, B.L. ); Dale, S.J. )

    1990-05-01

    This authors discuss the effects of geomagnetic disturbances on power systems. They also discuss the effects of geomagnetic storms on spacecraft electronics, pipelines, and geophysical surveys for oil and minerals. The current satellite system technology used in geomagnetic disturbance forecasts is described and assessed.

  16. Small satellite radiometric measurements

    SciTech Connect

    Weber, P.G.

    1991-01-01

    A critical need for the Mission to Planet Earth is to provide continuous, well-calibrated radiometric data for the radiation budget. This paper describes a new, compact, flexible radiometer which will provide both spectrally integrated data and data in selected spectral bands. The radiometer design is suitable for use on small satellites, aircraft, or remotely piloted vehicles (RPVs). 12 refs., 2 figs.

  17. Building Satellites is Easier

    NASA Technical Reports Server (NTRS)

    Marsh, Phyllis Nimmo

    1996-01-01

    'Building Satellites' is a story about Jim Marsh's recovery from a severe head injury told by his wife Phyllis from the moment she learned of its happening, through the ups and downs of a lengthy rehabilitation, until his return to work and daily living. It continues on, however, and narrates his battle with the more insidious Grave's disease. Told in the first person, 'Building Satellites' vividly portrays Phyllis's thoughts and feelings throughout this experience with scrupulous honestly. This is a story worth reading for many reasons. First of all, Jim was an accomplished scientist, respected by his colleagues both in this country and abroad. Secondly, it narrates the many stages of his recovery from head injury with detailed readable accuracy; it informs us as well as inspires. Finally, 'Building Satellites" also tells us the story of Phyllis Marsh's remarkable creative response to this crisis. It narrates her personal experiences as she progresses through the strange and somewhat bizarre world of medicine and rehabilitation, guided by a few basic beliefs, which she learned as a child in Iowa, that provided her with the strength to endure. 'Building Satellites' seems to reaffirm our unconscious, but settled conviction, that when confornted overnight with adversity, we are somehow given the means for coping, supported by our basic beliefs, strengthened by family and friends, and eventually learning to accept any outcome.

  18. Creating Better Satellite Conferences.

    ERIC Educational Resources Information Center

    Horner, Tommy

    1998-01-01

    Presents four ways to improve broadcasts of company satellite conferences, including creative site selection (using facilities at educational institutions rather than hotel rooms); creative programming (using graphics and other interruptions to break up lectures or speeches); creative crew selection; and creative downlink site activities (to…

  19. Domestic Communications Satellites.

    ERIC Educational Resources Information Center

    Network Project Notebook, 1972

    1972-01-01

    The June, 1972 Federal Communications Commission's (FCC) decision allowed an "open skies" policy in regard to domestic communication satellites and raised Liberal opposition to a situation where exclusive and unchecked communications power is now in the hands of private entrepreneurs, primarily the big Defense Department oriented aerospace…

  20. Satellite Town Meeting.

    ERIC Educational Resources Information Center

    Department of Education, Washington, DC.

    On the third Tuesday of each month, U.S. Secretary of Education, Richard W. Riley, and Deputy Secretary, Madeleine M. Kunin, host the Satellite Town Meeting--a live, interactive teleconference where renowned national experts, local educators, and community leaders share ideas on how to improve schools and reach the National Educational Goals. It…

  1. Data distribution satellite

    NASA Technical Reports Server (NTRS)

    Price, Kent M.; Jorasch, Ronald E.; Wiskerchen, Michael J.

    1991-01-01

    A description is given of a data distribution satellite (DDS) system. The DDS would operate in conjunction with the tracking and data relay satellite system to give ground-based users real time, two-way access to instruments in space and space-gathered data. The scope of work includes the following: (1) user requirements are derived; (2) communication scenarios are synthesized; (3) system design constraints and projected technology availability are identified; (4) DDS communications payload configuration is derived, and the satellite is designed; (5) requirements for earth terminals and network control are given; (6) system costs are estimated, both life cycle costs and user fees; and (7) technology developments are recommended, and a technology development plan is given. The most important results obtained are as follows: (1) a satellite designed for launch in 2007 is feasible and has 10 Gb/s capacity, 5.5 kW power, and 2000 kg mass; (2) DDS features include on-board baseband switching, use of Ku- and Ka-bands, multiple optical intersatellite links; and (3) system user costs are competitive with projected terrestrial communication costs.

  2. Satellite camera image navigation

    NASA Technical Reports Server (NTRS)

    Kamel, Ahmed A. (Inventor); Graul, Donald W. (Inventor); Savides, John (Inventor); Hanson, Charles W. (Inventor)

    1987-01-01

    Pixels within a satellite camera (1, 2) image are precisely located in terms of latitude and longitude on a celestial body, such as the earth, being imaged. A computer (60) on the earth generates models (40, 50) of the satellite's orbit and attitude, respectively. The orbit model (40) is generated from measurements of stars and landmarks taken by the camera (1, 2), and by range data. The orbit model (40) is an expression of the satellite's latitude and longitude at the subsatellite point, and of the altitude of the satellite, as a function of time, using as coefficients (K) the six Keplerian elements at epoch. The attitude model (50) is based upon star measurements taken by each camera (1, 2). The attitude model (50) is a set of expressions for the deviations in a set of mutually orthogonal reference optical axes (x, y, z) as a function of time, for each camera (1, 2). Measured data is fit into the models (40, 50) using a walking least squares fit algorithm. A transformation computer (66 ) transforms pixel coordinates as telemetered by the camera (1, 2) into earth latitude and longitude coordinates, using the orbit and attitude models (40, 50).

  3. Satellite Weather Watch.

    ERIC Educational Resources Information Center

    Summers, R. Joe

    1982-01-01

    Describes an inexpensive (about $1,500) direct-readout ground station for use in secondary school science/mathematics programs. Includes suggested activities including, among others, developing map overlays, operating station equipment, interpreting satellite data, developing weather forecasts, and using microcomputers for data storage, orbit…

  4. Perception via satellite

    USGS Publications Warehouse

    Robinove, Charles J.

    1970-01-01

    The earth resources observation satellite (EROS) program in the Department of the Interior is intended to gather and use data from satellites and aircraft on natural and man-made features of the earth's surface. Earth resources technology satellite will provide the EROS program with data for use in dealing with natural resource problems and understanding the interaction between man and the environment. Applications will include studies of tectonic features, hydrologic problems, location of fish schools, determination of the conditions of range land, mapping land use for urban planning, studies of erosion and change along coastlines and major streams, and inventories of land use and land forms. In addition, the ERTS data may be used for detecting forest and crop diseases and inventorying crops. The ERTS satellite will be in a polar, sun-synchronous orbit so that each point on the earth's surface will be sensed every 17 to 20 days, at the same time of day. Multispectral photography is being investigated for its usefulness in hydrology. Side-looking airborne radar has not yet been widely used in hydrologic studies, although it is an excellent tool for all-weather, day or night, coverage of large areas. Other techniques being investigated include passive microwave radiometry, ultraviolet and visible stimulated luminescence, and absorption spectroscopy.

  5. On satellite constellation selection

    SciTech Connect

    Canavan, G.H.

    1991-05-01

    Analytical estimates can be used to produce and discuss optimal constellations. They are in close agreement with phase-space estimates and exact solutions. They suggest that distributions of inclined orbits could reduce satellite numbers by factors of 2--3 while improving uniformity. 4 refs., 2 figs.

  6. Retroreflector spherical satellite

    NASA Astrophysics Data System (ADS)

    Akentyev, A. S.; Vasiliev, V. P.; Sadovnikov, M. A.; Sokolov, A. L.; Shargorodskiy, V. D.

    2015-10-01

    Specific features of spherical retroreflector arrays for high-precision laser ranging are considered, and errors in distance measurements are analyzed. A version of a glass retroreflector satellite with a submillimeter "target error" is proposed. Its corner cube reflectors are located in depressions to reduce the working angular aperture, and their faces have a dielectric interference coating.

  7. Mobile satellite ranging

    NASA Technical Reports Server (NTRS)

    Silverberg, E. C.

    1978-01-01

    A brief review of the constraints which have limited satellite ranging hardware and an outline of the steps which are underway to improve the status of the equipment in this area are given. In addition, some suggestions are presented for the utilization of newer instruments and for possible future research and development work in this area.

  8. Experimental Satellite Quantum Communications

    NASA Astrophysics Data System (ADS)

    Vallone, Giuseppe; Bacco, Davide; Dequal, Daniele; Gaiarin, Simone; Luceri, Vincenza; Bianco, Giuseppe; Villoresi, Paolo

    2015-07-01

    Quantum communication (QC), namely, the faithful transmission of generic quantum states, is a key ingredient of quantum information science. Here we demonstrate QC with polarization encoding from space to ground by exploiting satellite corner cube retroreflectors as quantum transmitters in orbit and the Matera Laser Ranging Observatory of the Italian Space Agency in Matera, Italy, as a quantum receiver. The quantum bit error ratio (QBER) has been kept steadily low to a level suitable for several quantum information protocols, as the violation of Bell inequalities or quantum key distribution (QKD). Indeed, by taking data from different satellites, we demonstrate an average value of QBER =4.6 % for a total link duration of 85 s. The mean photon number per pulse μsat leaving the satellites was estimated to be of the order of one. In addition, we propose a fully operational satellite QKD system by exploiting our communication scheme with orbiting retroreflectors equipped with a modulator, a very compact payload. Our scheme paves the way toward the implementation of a QC worldwide network leveraging existing receivers.

  9. Experimental Satellite Quantum Communications.

    PubMed

    Vallone, Giuseppe; Bacco, Davide; Dequal, Daniele; Gaiarin, Simone; Luceri, Vincenza; Bianco, Giuseppe; Villoresi, Paolo

    2015-07-24

    Quantum communication (QC), namely, the faithful transmission of generic quantum states, is a key ingredient of quantum information science. Here we demonstrate QC with polarization encoding from space to ground by exploiting satellite corner cube retroreflectors as quantum transmitters in orbit and the Matera Laser Ranging Observatory of the Italian Space Agency in Matera, Italy, as a quantum receiver. The quantum bit error ratio (QBER) has been kept steadily low to a level suitable for several quantum information protocols, as the violation of Bell inequalities or quantum key distribution (QKD). Indeed, by taking data from different satellites, we demonstrate an average value of QBER=4.6% for a total link duration of 85 s. The mean photon number per pulse μ_{sat} leaving the satellites was estimated to be of the order of one. In addition, we propose a fully operational satellite QKD system by exploiting our communication scheme with orbiting retroreflectors equipped with a modulator, a very compact payload. Our scheme paves the way toward the implementation of a QC worldwide network leveraging existing receivers.

  10. Discovery of 12 satellites of Saturn exhibiting orbital clustering.

    PubMed

    Gladman, B; Kavelaars, J J; Holman, M; Nicholson, P D; Burns, J A; Hergenrother, C W; Petit, J M; Marsden, B G; Jacobson, R; Gray, W; Grav, T

    2001-07-12

    The giant planets in the Solar System each have two groups of satellites. The regular satellites move along nearly circular orbits in the planet's orbital plane, revolving about it in the same sense as the planet spins. In contrast, the so-called irregular satellites are generally smaller in size and are characterized by large orbits with significant eccentricity, inclination or both. The differences in their characteristics suggest that the regular and irregular satellites formed by different mechanisms: the regular satellites are believed to have formed in an accretion disk around the planet, like a miniature Solar System, whereas the irregulars are generally thought to be captured planetesimals. Here we report the discovery of 12 irregular satellites of Saturn, along with the determinations of their orbits. These orbits, along with the orbits of irregular satellites of Jupiter and Uranus, fall into groups on the basis of their orbital inclinations. We interpret this result as indicating that most of the irregular moons are collisional remnants of larger satellites that were fragmented after capture, rather than being captured independently. PMID:11449267

  11. Small satellite space operations

    NASA Technical Reports Server (NTRS)

    Reiss, Keith

    1994-01-01

    CTA Space Systems has played a premier role in the development of the 'lightsat' programs of the 80's and 90's. The high costs and development times associated with conventional LEO satellite design, fabrication, launch, and operations continue to motivate the development of new methodologies, techniques, and generally low cost and less stringently regulated satellites. These spacecraft employ low power 'lightsat' communications (versus TDRSS for NASA's LEO's) and typically fly missions with payload/experiment suites that can succeed, for example, without heavily redundant backup systems and large infrastructures of personnel and ground support systems. Such small yet adaptable satellites are also typified by their very short contract-to-launch times (often one to two years). This paper reflects several of the methodologies and perspectives of our successful involvement in these innovative programs and suggests how they might relieve NASA's mounting pressures to reduce the cost of both the spacecraft and their companion mission operations. It focuses on the use of adaptable, sufficiently powerful yet inexpensive PC-based ground systems for wide ranging user terminal (UT) applications and master control facilities for mission operations. These systems proved themselves in successfully controlling more than two dozen USAF, USN, and ARPA satellites at CTA/SS. UT versions have linked with both GEO and LEO satellites and functioned autonomously in relay roles often in remote parts of the world. LEO applications particularly illustrate the efficacy of these concepts since a user can easily mount a lightweight antenna, usually an omni or helix with light duty rotors and PC-based drivers. A few feet of coax connected to a small transceiver module (the size of a small PC) and a serial line to an associated PC establishes a communications link and together with the PC constitute a viable ground station. Applications included geomagnetic mapping; spaceborne solid state

  12. Cibola flight experiment satellite

    NASA Astrophysics Data System (ADS)

    Davies, P.; Liddle, Doug; Paffett, John; Sweeting, Martin; Curiel, A.; Sun, Wei; Eves, Stuart

    2004-11-01

    In order to achieve an "economy of scale" with respect to payload capacity the major trend in telecommunications satellites is for larger and larger platforms. With these large platforms the level of integration between platform and payload is increasing leading to longer delivery schedules. The typical lifecycle for procurement of these large telecommunications satellites is now 3-6 years depending on the level of non-recurring engineering needed. Surrey Satellite Technology Ltd (SSTL) has designed a low-cost platform aimed at telecommunications and navigation applications. SSTL's Geostationary Minisatellite Platform (GMP) is a new entrant addressing the lower end of the market with payloads up to 250kg requiring less than 1.5 kW power. The British National Space Centre through the MOSAIC Small Satellite Initiative supported the development of GMP. The main design goals for GMP are low-cost for the complete mission including launch and operations and a platform allowing flexible payload accommodation. GMP is specifically designed to allow rapid development and deployment with schedules typically between 1 and 2 years from contract signature to flight readiness. GMP achieves these aims by a modular design where the level of integration between the platform and payload is low. The modular design decomposes the satellite into three major components - the propulsion bay, the avionics bay and the payload module. Both the propulsion and avionics bays are reusable, largely unchanged, and independent of the payload configuration. Such a design means that SSTL or a 3rd party manufacturer can manufacture the payload in parallel to the platform with integration taking place quite late in the schedule. In July 2003 SSTL signed a contract for ESA's first Galileo navigation satellite known as GSTBV2/A. The satellite is based on GMP and ESA plan to launch it into a MEO orbit late in 2005. The second flight of GMP is likely to be in 2006 carrying a geostationary payload

  13. Visuo-spatial learning and memory deficits on the Barnes maze in the 16-month-old APPswe/PS1dE9 mouse model of Alzheimer's disease.

    PubMed

    O'Leary, Timothy P; Brown, Richard E

    2009-07-19

    The APPswe/PS1dE9 mouse is a double transgenic model of Alzheimer's disease, which harbors mutant mouse/human amyloid precursor protein (Swedish K594N/M595L) and presenilin-1 genes (PS1-dE9). These mice develop beta-amyloid plaques and exhibit visuo-spatial learning and memory impairment in the Morris water maze (MWM) at 8-12 and 16-18 months of age. To extend these findings, we tested visuo-spatial learning and memory of male and female APPswe/PS1dE9 mice at 16 months of age on the Barnes maze. APPswe/PS1dE9 mice showed impaired acquisition learning using measures of latency, distance traveled, errors and hole deviation scores, and were less likely to use the spatial search strategy to locate the escape hole than wild-type mice. APPswe/PS1dE9 mice also showed a deficit in memory in probe tests on the Barnes maze relative to wild-type mice. Learning and memory deficits, however, were not found during reversal training and reversal probe tests. Sex differences were observed, as male APPswe/PS1dE9 mice had smaller reversal effects than male wild-type mice, but females of each genotype did not differ. Overall, these results replicate previous findings using the MWM, and indicate that APPswe/PS1dE9 mice have impaired visuo-spatial learning and memory at 16 months of age. PMID:19428625

  14. Aqua satellite orbiting the Earth

    NASA Video Gallery

    This animation shows the Aqua satellite orbiting the Earth on August 27, 2005 by revealing MODIS true-color imagery for that day. This animation is on a cartesian map projection, so the satellite w...

  15. Meteorological measurements from satellite platforms

    NASA Technical Reports Server (NTRS)

    Suomi, V. E.

    1972-01-01

    Quantitative exploitation of meteorological data from geosynchronous satellites is starting to move from the laboratory to operational practice. Investigations of the data applications portion of the total meteorological satellite system include: (1) tropospheric wind shear and the related severe storm circulations; (2) kinematic properties of the tropical atmosphere as derived from cloud motion vectors; (3) application of a geostationary satellite rake system to measurements of rainfall; and (4) pointing error analysis of geosynchronous satellites.

  16. Mobile satellite service for Canada

    NASA Technical Reports Server (NTRS)

    Sward, David

    1988-01-01

    The Mobile Satellite (MSAT) system and a special program designed to provide interim mobile satellite services (IMSS) during the construction phase of MSAT are described. A mobile satellite system is a key element in extending voice and and data telecommunications to all Canadians.

  17. Telelibrary: Library Services via Satellite.

    ERIC Educational Resources Information Center

    Liu, Rosa

    1979-01-01

    Investigates the provision of library services via satellite, explains briefly the operation and advantages of communication satellites, and discusses the various telecommunications equipment and services which, when coupled with satellite transmission, will enhance library activities. Demand trend projections for telecommunications services…

  18. TriAnd and its siblings: satellites of satellites in the Milky Way halo

    NASA Astrophysics Data System (ADS)

    Deason, A. J.; Belokurov, V.; Hamren, K. M.; Koposov, S. E.; Gilbert, K. M.; Beaton, R. L.; Dorman, C. E.; Guhathakurta, P.; Majewski, S. R.; Cunningham, E. C.

    2014-11-01

    We explore the Triangulum-Andromeda (TriAnd) overdensity in the SPLASH (Spectroscopic and Photometric Landscape of Andromeda's Stellar Halo) and SEGUE (the Sloan Extension for Galactic Understanding and Exploration) spectroscopic surveys. Milky Way main-sequence turn-off stars in the SPLASH survey reveal that the TriAnd overdensity and the recently discovered Pan-Andromeda Archaeological Survey (PAndAS) stream share a common heliocentric distance (D ˜ 20 kpc), position on the sky, and line-of-sight velocity (VGSR ˜ 50 km s-1). Similarly, A-type, giant, and main-sequence turn-off stars selected from the SEGUE survey in the vicinity of the Segue 2 satellite show that TriAnd is prevalent in these fields, with a velocity and distance similar to Segue 2. The coincidence of the PAndAS stream and Segue 2 satellite in positional and velocity space to TriAnd suggests that these substructures are all associated, and may be a fossil record of group-infall on to the Milky Way halo. In this scenario, the Segue 2 satellite and PAndAS stream are `satellites of satellites', and the large, metal-rich TriAnd overdensity is the remains of the group central.

  19. Neuroendocrine immunomodulation network dysfunction in SAMP8 mice and PrP-hAβPPswe/PS1ΔE9 mice: potential mechanism underlying cognitive impairment

    PubMed Central

    Wang, Jian-hui; Cheng, Xiao-rui; Zhang, Xiao-rui; Wang, Tong-xing; Xu, Wen-jian; Li, Fei; Liu, Feng; Cheng, Jun-ping; Bo, Xiao-chen; Wang, Sheng-qi; Zhou, Wen-xia; Zhang, Yong-xiang

    2016-01-01

    Senescence-accelerated mouse prone 8 strain (SAMP8) and PrP-hAβPPswe/PS1ΔE9 (APP/PS1) mice are classic animal models of sporadic Alzheimer's disease and familial AD respectively. Our study showed that object recognition memory, spatial learning and memory, active and passive avoidance were deteriorated and neuroendocrine immunomodulation (NIM) network was imbalance in SAMP8 and APP/PS1 mice. SAMP8 and APP/PS1 mice had their own specific phenotype of cognition, neuroendocrine, immune and NIM molecular network. The endocrine hormone corticosterone, luteinizing hormone and follicle-stimulating hormone, chemotactic factor monocyte chemotactic protein-1, macrophage inflammatory protein-1β, regulated upon activation normal T cell expressed and secreted factor and eotaxin, pro-inflammatory factor interleukin-23, and the Th1 cell acting as cell immunity accounted for cognitive deficiencies in SAMP8 mice, while adrenocorticotropic hormone and gonadotropin-releasing hormone, colony stimulating factor granulocyte colony stimulating factor, and Th2 cell acting as humoral immunity in APP/PS1 mice. On the pathway level, chemokine signaling and T cell receptor signaling pathway played the key role in cognition impairments of two models, while cytokine-cytokine receptor interaction and natural killer cell mediated cytotoxicity were more important in cognitive deterioration of SAMP8 mice than APP/PS1 mice. This mechanisms of NIM network underlying cognitive impairment is significant for further understanding the pathogenesis of AD and can provide useful information for development of AD therapeutic drug. PMID:27049828

  20. Validation of satellite rainfall products over Greece

    NASA Astrophysics Data System (ADS)

    Feidas, H.

    2010-01-01

    Six widely available satellite precipitation products were extensively validated and intercompared on monthly-to-seasonal timescales and various spatial scales, for the period 1998-2006, using a dense station network over Greece. Satellite products were divided into three groups according to their spatial resolution. The first group had high spatial (0.5°) resolution and consists only of Tropical Rainfall Measuring Mission (TRMM) products: the TRMM Microwave Imager (TMI) precipitation product (3A12) and the TRMM multisatellite precipitation analysis products (3B42 and 3B43). The second group comprised products with medium spatial (1°) resolution. These products included the TRMM 3B42 and 3B43 estimates (remapped to 1° resolution) and the Global Precipitation Climatology Project one-degree daily (GPCP-1DD) analysis. The third group consisted of low spatial (2.5°) resolution products and included the 3B43 product (remapped to 2.5° resolution), the GPCP Satellite and Gauge (GPCP-SG) product, and the National Oceanographic and Atmospheric Administration Climate Prediction Center (NOAA-CPC) Merged Analysis (CMAP). Rain gauge data were first gridded and then compared with monthly and seasonal precipitation totals as well as with long-term averages of the six satellite products at different spatial resolutions (2.5°, 1°, and 0.5°). The results demonstrated the excellent performance of the 3B43 product over Greece in all three spatial scales. 3B42 from the first and second group and CMAP from the third exhibited a reasonable skill.

  1. Asymptotic Behavior of an Elastic Satellite with Internal Friction

    NASA Astrophysics Data System (ADS)

    Haus, E.; Bambusi, D.

    2015-12-01

    We study the dynamics of an elastic body whose shape and position evolve due to the gravitational forces exerted by a pointlike planet. The main result is that, if all the deformations of the satellite dissipate some energy, then under a suitable nondegeneracy condition there are only three possible outcomes for the dynamics: (i) the orbit of the satellite is unbounded, (ii) the satellite falls on the planet, (iii) the satellite is captured in synchronous resonance i.e. its orbit is asymptotic to a motion in which the barycenter moves on a circular orbit, and the satellite moves rigidly, always showing the same face to the planet. The result is obtained by making use of LaSalle's invariance principle and by a careful kinematic analysis showing that energy stops dissipating only on synchronous orbits. We also use in quite an extensive way the fact that conservative elastodynamics is a Hamiltonian system invariant under the action of the rotation group.

  2. An aeronautical mobile satellite experiment

    NASA Technical Reports Server (NTRS)

    Jedrey, T. C.; Dessouky, K. I.; Lay, N. E.

    1990-01-01

    The various activities and findings of a NASA/FAA/COMSAT/INMARSAT collaborative aeronautical mobile satellite experiment are detailed. The primary objective of the experiment was to demonstrate and evaluate an advanced digital mobile satellite terminal developed at the Jet Propulsion Laboratory under the NASA Mobile Satellite Program. The experiment was a significant milestone for NASA/JPL, since it was the first test of the mobile terminal in a true mobile satellite environment. The results were also of interest to the general mobile satellite community because of the advanced nature of the technologies employed in the terminal.

  3. LDEF Satellite Radiation Analyses

    NASA Technical Reports Server (NTRS)

    Armstrong, T. W.; Colborn, B. L.

    1996-01-01

    This report covers work performed by Science Applications International Corporation (SAIC) under contract NAS8-39386 from the NASA Marshall Space Flight Center entitled LDEF Satellite Radiation Analyses. The basic objective of the study was to evaluate the accuracy of present models and computational methods for defining the ionizing radiation environment for spacecraft in Low Earth Orbit (LEO) by making comparisons with radiation measurements made on the Long Duration Exposure Facility (LDEF) satellite, which was recovered after almost six years in space. The emphasis of the work here is on predictions and comparisons with LDEF measurements of induced radioactivity and Linear Energy Transfer (LET) measurements. These model/data comparisons have been used to evaluate the accuracy of current models for predicting the flux and directionality of trapped protons for LEO missions.

  4. Declassified Intelligence Satellite Photographs

    USGS Publications Warehouse

    ,

    2008-01-01

    Declassified photographs from U.S. intelligence satellites provide an important worldwide addition to the public record of the Earth's land surface. This imagery was released to the National Archives and Records Administration (NARA) and the U.S. Geological Survey (USGS) in accordance with Executive Order 12951 on February 23, 1995. The NARA has the original declassified film and a viewing copy. The USGS has another copy of the film to complement the Landsat archive. The declassified collection involves more than 990,000 photographs taken from 1959 through 1980 and was released on two separate occasions: February 1995 (Declass 1) and September 2002 (Declass 2). The USGS copy is maintained by the Earth Resources Observation and Science (EROS) Center, near Sioux Falls, South Dakota. Both the NARA and EROS provide public access to this unique collection that extends the record of land-surface change back another decade from the advent of the Landsat program that began satellite operations in 1972.

  5. Balancing Vanguard Satellites

    NASA Technical Reports Server (NTRS)

    Simkovich, A.; Baumann, Robert C.

    1961-01-01

    The Vanguard satellites and component parts were balanced within the specified limits by using a Gisholt Type-S balancer in combination with a portable International Research and Development vibration analyzer and filter, with low-frequency pickups. Equipment and procedures used for balancing are described; and the determination of residual imbalance is accomplished by two methods: calculation, and graphical interpretation. Between-the-bearings balancing is recommended for future balancing of payloads.

  6. Satellite freeze forecast system

    NASA Technical Reports Server (NTRS)

    Martsolf, J. D. (Principal Investigator)

    1983-01-01

    Provisions for back-up operations for the satellite freeze forecast system are discussed including software and hardware maintenance and DS/1000-1V linkage; troubleshooting; and digitized radar usage. The documentation developed; dissemination of data products via television and the IFAS computer network; data base management; predictive models; the installation of and progress towards the operational status of key stations; and digital data acquisition are also considered. The d addition of dew point temperature into the P-model is outlined.

  7. The European Communications Satellite

    NASA Astrophysics Data System (ADS)

    Stone, T. A.

    1985-09-01

    Two European Communication Satellites (ECSs) are now in operation for Eutelsat, forming the orbital portion of a communications system that will operate until 1993, carrying telephony and TV for the European Broadcasting Union. A total of five ECSs are to be constructed in order to ensure continuity of service over the systems lifetime. ECSs will also serve as the bases for the European Regional Communication System, which furnishes small receiver dish specialized services and preemptive TV distribution channels within Europe.

  8. ASPEC: Solar power satellite

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The solar power satellite (SPS) will provide a clean, reliable source of energy for large-scale consumption. The system will use satellites in geostationary orbits around the Earth to capture the Sun's energy. The intercepted sunlight will be converted to laser beam energy that can be transmitted to the Earth's surface. Ground systems on the Earth will convert the transmissions from space into electric power. The preliminary design for the SPS consists of one satellite in orbit around the Earth transmitting energy to a single ground station. The SPS design uses multilayer solar cell technology arranged on a 20 km squared planar array to intercept sunlight and convert it to an electric voltage. Power conditioning devices then send the electricity to a laser, which transmits the power to the surface of the Earth. A ground station will convert the beam into electricity. Typically, a single SPS will supply 5 GW of power to the ground station. Due to the large mass of the SPS, about 41 million kg, construction in space is needed in order to keep the structural mass low. The orbit configuration for this design is to operate a single satellite in geosynchronous orbit (GEO). The GEO allows the system to be positioned above a single receiving station and remain in sunlight 99 percent of the time. Construction will take place in low Earth orbit (LEO); array sections, 20 in total, will be sailed on solar wind out to the GEO location in 150 days. These individual transportation sections are referred to as solar sailing array panels (SSAP's). The primary truss elements used to support the array are composed of composite tubular members in a pentahedral arrangement. Smart segments consisting of passive and active damping devices will increase the control of dynamic SPS modes.

  9. Satellite servicing economic study

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Previous studies have shown that satellite servicing is cost effective; however, all of these studies were of different formats, dollar year, learning rates, availability, etc. Threfore, it was difficult to correlate any useful trends from these studies. The reviewed study was initiated to correlate the economic data into a common data base, using a common set of assumptions. A selected set of existed funded programs was then analyzed to provide an independent analysis of the servicing options and potential economic benefits.

  10. Satellite servicing economic study

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Previous studies have shown that satellite servicing is cost effective; however, all of these studies were of different formats, dollar year, learning rates, availability, etc. Therefore, it was difficult to correlate any useful trends from these studies. The reviewed study was initiated to correlate the economic data into a common data base, using a common set of assumptions. A selected set of existed funded programs was then analyzed to provide an independent analysis of the servicing options and potential economic benefits.

  11. Experimental and DFT studies on the vibrational and electronic spectra and NBO analysis of 2-amino-3-((E)-(9-p-tolyl-9H-carbazol-3-yl) methyleneamino) maleonitrile.

    PubMed

    Meng, Nana; Zhang, Yu; Wang, Yiwei; Ma, Kuirong; Zhao, Jianying; Tang, Guodong

    2014-01-01

    2-Amino-3-((E)-(9-p-tolyl-9H-carbazol-3-yl) methyleneamino) maleonitrile (ACMM) was synthesized and characterized by X-ray diffraction, FT-IR, FT-Raman and UV-Vis spectra. The X-ray diffraction study showed that ACMM has a Z-configuration, due to the intramolecular C18H18A⋯N2, N3H3A⋯N2 and C20H20A⋯N4 hydrogen bonds and intermolecular C10H10A⋯N4, N3H3B⋯N9 (2-x, 2-y, 2-z) and N3H8C⋯N4 (2-x, 1-y, 2-z) hydrogen bonds. The benzene ring including methyl is twisted from the mean plane of the carbazole group by 59.7(3)°. Vibrational spectra and electronic spectra measurements were made for the compound. Optimized geometrical structure and harmonic vibrational frequencies were computed with DFT (B3-based B3P86, B3LYP, B3PW91 and B-based BP86, BLYP, BPW91) methods and ab initio RHF method using 6-311++G(d, p) basis set. Assignments of the observed spectra were proposed. The equilibrium geometries computed by all of the methods were compared with X-ray diffraction results. The absorption spectra of the title compound were computed both in gas phase and in DMF solution using TD-B3LYP/6-311++G(d, p) and PCM-B3LYP/6-311++G(d, p) approaches, respectively. The calculated results provide a good description of positions of the bands maxima in the observed electronic spectrum. Temperature dependence of thermodynamic parameters in the range of 100-1000K were determined. The bond orbital occupancies, contribution from parent natural bond orbital (NBO), the natural atomic hybrids was calculated and discussed.

  12. Laser satellite power systems

    SciTech Connect

    Walbridge, E.W.

    1980-01-01

    A laser satellite power system (SPS) converts solar power captured by earth-orbiting satellites into electrical power on the earth's surface, the satellite-to-ground transmission of power being effected by laser beam. The laser SPS may be an alternative to the microwave SPS. Microwaves easily penetrate clouds while laser radiation does not. Although there is this major disadvantage to a laser SPS, that system has four important advantages over the microwave alternative: (1) land requirements are much less, (2) radiation levels are low outside the laser ground stations, (3) laser beam sidelobes are not expected to interfere with electromagnetic systems, and (4) the laser system lends itself to small-scale demonstration. After describing lasers and how they work, the report discusses the five lasers that are candidates for application in a laser SPS: electric discharge lasers, direct and indirect solar pumped lasers, free electron lasers, and closed-cycle chemical lasers. The Lockheed laser SPS is examined in some detail. To determine whether a laser SPS will be worthy of future deployment, its capabilities need to be better understood and its attractiveness relative to other electric power options better assessed. First priority should be given to potential program stoppers, e.g., beam attenuation by clouds. If investigation shows these potential program stoppers to be resolvable, further research should investigate lasers that are particularly promising for SPS application.

  13. Perturbed Trojan satellites

    NASA Astrophysics Data System (ADS)

    Morais, M. H. M.; Murray, C. D.

    1999-09-01

    We present some mechanisms that can lead to instability of initially small eccentricity Trojan-type orbits associated with planetary satellites. Dermott & Murray (1981) showed that in the context of the hierarchical restricted three-body problem (M>> m), stable small eccentricity coorbital motion associated with the mass m, occurs within a region of relative width in semi-major axis a_s=0.74 epsilon (where epsilon is the dimensionless Hill's radius). However, for large eccentricities, the size of the stable coorbital region shrinks as a_s=4 (epsilon /e)(1/2) epsilon (Namouni 1999). The perturbations from other nearby bodies can cause increases in both eccentricity and semi-major axis, leading to ejection from the coorbital region via collisions with the parent body or a nearby perturber. We show that mean motion resonances among saturnian satellites can cause chaotic diffusion of both the eccentricity and the semi-major axis of their associated Trojan orbits. Moreover, we show that secular resonances inside the coorbital regions of some uranian and saturnian satellites can induce significant increases in the eccentricity of Trojan objects. A better insight into the complicated dynamics exhibited by Trojan objects when they are being subject to perturbations is fundamental to be able to assess the likelihood of finding real examples of these configurations. Dermott & Murray (1981). Icarus 48, 1-11. Namouni (1999). Icarus 137, 293-314.

  14. Neptune - three new satellites

    NASA Technical Reports Server (NTRS)

    1989-01-01

    This image captured by the Voyager 2 spacecraft was used to confirm the discovery of three new satellites orbiting Neptune. The 46 second exposure was taken by Voyager 2's narrow angle camera through a clear filter on July 30, 1989, when the spacecraft was about 37.3 million kilometers (23.6 million miles) from Neptune. The large globe of the planet itself is severely overexposed and appears pure white. The image has been computer processed to accentuate the new moons, which otherwise would appear little stronger than background noise. The satellite 1989 N1, at right in this frame, was discovered by Voyager 2 in early July 1989. The new satellites confirmed this week are 1989 N2, 1989 N3 and 1989 N4. Each of the moons appears as a small streak, an effect caused by movement of the spacecraft during the long exposure. The new moons occupy nearly circular and equatorial orbits ranging from about 27,300 to 48,300 kilometers (17,000 to 30,000 miles) from Neptune's cloud tops, and are estimated to range in diameter from about 100 to 200 kilometers (about 60 to 125 miles). The Voyager Mission is conducted by the Jet Propulsion Laboratory for NASA's Office of Space Science and Applications.

  15. Heart Monitoring By Satellite

    NASA Technical Reports Server (NTRS)

    1978-01-01

    The ambulance antenna shown is a specially designed system that allows satellite-relayed two-way communications between a moving emergency vehicle and a hospital emergency room. It is a key component of a demonstration program aimed at showing how emergency medical service can be provided to people in remote rural areas. Satellite communication permits immediate, hospital- guided treatment of heart attacks or other emergencies by ambulance personnel, saving vital time when the scene of the emergency is remote from the hospital. If widely adopted, the system could save tens of thousands of lives annually in the U.S. alone, medical experts say. The problem in conventional communication with rural areas is the fact that radio signals travel in line of sight. They may be blocked by tall buildings, hills and mountains, or even by the curvature of the Earth, so signal range is sharply limited. Microwave relay towers could solve the problem, but a complete network of repeater towers would be extremely expensive. The satellite provides an obstruction-free relay station in space.

  16. Origin of the Uranian satellites

    NASA Technical Reports Server (NTRS)

    Pollack, James B.; Lunine, Jonathan I.; Tittemore, William C.

    1991-01-01

    The current understanding of the origin of the Uranian satellites is assessed by reviewing relevant data on the Uranian satellites, including those obtained by Voyager, and comparing these properties with those of the satellites of the other outer planets. The nature of the early solar system, including the origin of the giant planets, is discussed as a preface to alternative hypotheses for the origin of the nebular disk within which the Uranian satellites formed. The chemical and physical properties of this disk are discussed, as well as the accretion of the satellites from disk solid matter. Predictions of alternative scenarios for the satellites' origin with the relevant observational constraint are compared. The orbital evolution of the larger satellites of Uranus is discussed to gain an understanding of their present orbital properties and possibly important past tidal heating episodes.

  17. Communications satellites - The experimental years

    NASA Technical Reports Server (NTRS)

    Edelson, B. I.

    1983-01-01

    Only eight years after the launc of Sputnik-1 by the Soviet Union, the first commercial satellite, 'Early Bird', entered service. In just twelve years commercial satellite service extended around the earth and became profitable. The reasons for the successful development of the communications satellite services in a comparatively short time are considered. These reasons are related to the presence of three ingredients, taking into account technology to create the system, communications requirements to form a market, and a management structure to implement the system. The formation of the concept of using earth orbiting satellites for telecommunications is discussed. It is pointed out that the years from 1958 to 1964 were the true 'experimental years' for satellite communications. The rapid development of technology during this crucial period is described, giving attention to passive satellites, active systems, and development satellites.

  18. Communications satellites - The experimental years

    NASA Astrophysics Data System (ADS)

    Edelson, B. I.

    1983-10-01

    Only eight years after the launc of Sputnik-1 by the Soviet Union, the first commercial satellite, 'Early Bird', entered service. In just twelve years commercial satellite service extended around the earth and became profitable. The reasons for the successful development of the communications satellite services in a comparatively short time are considered. These reasons are related to the presence of three ingredients, taking into account technology to create the system, communications requirements to form a market, and a management structure to implement the system. The formation of the concept of using earth orbiting satellites for telecommunications is discussed. It is pointed out that the years from 1958 to 1964 were the true 'experimental years' for satellite communications. The rapid development of technology during this crucial period is described, giving attention to passive satellites, active systems, and development satellites.

  19. Optical satellite communications in Europe

    NASA Astrophysics Data System (ADS)

    Sodnik, Zoran; Lutz, Hanspeter; Furch, Bernhard; Meyer, Rolf

    2010-02-01

    This paper describes optical satellite communication activities based on technology developments, which started in Europe more than 30 years ago and led in 2001 to the world-first optical inter-satellite communication link experiment (SILEX). SILEX proved that optical communication technologies can be reliably mastered in space and in 2006 the Japanese Space Agency (JAXA) joined the optical inter-satellite experiment from their own satellite. Since 2008 the German Space Agency (DLR) is operating an inter-satellite link between the NFIRE and TerraSAR-X satellites based on a second generation of laser communication technology, which will be used for the new European Data Relay Satellite (EDRS) system to be deployed in 2013.

  20. Tethered Satellite System Contingency Investigation Board

    NASA Technical Reports Server (NTRS)

    1992-01-01

    The Tethered Satellite System (TSS-1) was launched aboard the Space Shuttle Atlantis (STS-46) on July 31, 1992. During the attempted on-orbit operations, the Tethered Satellite System failed to deploy successfully beyond 256 meters. The satellite was retrieved successfully and was returned on August 6, 1992. The National Aeronautics and Space Administration (NASA) Associate Administrator for Space Flight formed the Tethered Satellite System (TSS-1) Contingency Investigation Board on August 12, 1992. The TSS-1 Contingency Investigation Board was asked to review the anomalies which occurred, to determine the probable cause, and to recommend corrective measures to prevent recurrence. The board was supported by the TSS Systems Working group as identified in MSFC-TSS-11-90, 'Tethered Satellite System (TSS) Contingency Plan'. The board identified five anomalies for investigation: initial failure to retract the U2 umbilical; initial failure to flyaway; unplanned tether deployment stop at 179 meters; unplanned tether deployment stop at 256 meters; and failure to move tether in either direction at 224 meters. Initial observations of the returned flight hardware revealed evidence of mechanical interference by a bolt with the level wind mechanism travel as well as a helical shaped wrap of tether which indicated that the tether had been unwound from the reel beyond the travel by the level wind mechanism. Examination of the detailed mission events from flight data and mission logs related to the initial failure to flyaway and the failure to move in either direction at 224 meters, together with known preflight concerns regarding slack tether, focused the assessment of these anomalies on the upper tether control mechanism. After the second meeting, the board requested the working group to complete and validate a detailed integrated mission sequence to focus the fault tree analysis on a stuck U2 umbilical, level wind mechanical interference, and slack tether in upper tether

  1. Intraganglionic interactions between satellite cells and adult sensory neurons.

    PubMed

    Christie, Kimberly; Koshy, Dilip; Cheng, Chu; Guo, GuiFang; Martinez, Jose A; Duraikannu, Arul; Zochodne, Douglas W

    2015-07-01

    Perineuronal satellite cells have an intimate anatomical relationship with sensory neurons that suggests close functional collaboration and mutual support. We examined several facets of this relationship in adult sensory dorsal root ganglia (DRG). Collaboration included the support of process outgrowth by clustering of satellite cells, induction of distal branching behavior by soma signaling, the capacity of satellite cells to respond to distal axon injury of its neighboring neurons, and evidence of direct neuron-satellite cell exchange. In vitro, closely adherent coharvested satellite cells routinely clustered around new outgrowing processes and groups of satellite cells attracted neurite processes. Similar clustering was encountered in the pseudounipolar processes of intact sensory neurons within intact DRG in vivo. While short term exposure of distal growth cones of unselected adult sensory neurons to transient gradients of a PTEN inhibitor had negligible impacts on their behavior, exposure of the soma induced early and substantial growth of their distant neurites and branches, an example of local soma signaling. In turn, satellite cells sensed when distal neuronal axons were injured by enlarging and proliferating. We also observed that satellite cells were capable of internalizing and expressing a neuron fluorochrome label, diamidino yellow, applied remotely to distal injured axons of the neuron and retrogradely transported to dorsal root ganglia sensory neurons. The findings illustrate a robust interaction between intranganglionic neurons and glial cells that involve two way signals, features that may be critical for both regenerative responses and ongoing maintenance. PMID:25979201

  2. Intraganglionic interactions between satellite cells and adult sensory neurons.

    PubMed

    Christie, Kimberly; Koshy, Dilip; Cheng, Chu; Guo, GuiFang; Martinez, Jose A; Duraikannu, Arul; Zochodne, Douglas W

    2015-07-01

    Perineuronal satellite cells have an intimate anatomical relationship with sensory neurons that suggests close functional collaboration and mutual support. We examined several facets of this relationship in adult sensory dorsal root ganglia (DRG). Collaboration included the support of process outgrowth by clustering of satellite cells, induction of distal branching behavior by soma signaling, the capacity of satellite cells to respond to distal axon injury of its neighboring neurons, and evidence of direct neuron-satellite cell exchange. In vitro, closely adherent coharvested satellite cells routinely clustered around new outgrowing processes and groups of satellite cells attracted neurite processes. Similar clustering was encountered in the pseudounipolar processes of intact sensory neurons within intact DRG in vivo. While short term exposure of distal growth cones of unselected adult sensory neurons to transient gradients of a PTEN inhibitor had negligible impacts on their behavior, exposure of the soma induced early and substantial growth of their distant neurites and branches, an example of local soma signaling. In turn, satellite cells sensed when distal neuronal axons were injured by enlarging and proliferating. We also observed that satellite cells were capable of internalizing and expressing a neuron fluorochrome label, diamidino yellow, applied remotely to distal injured axons of the neuron and retrogradely transported to dorsal root ganglia sensory neurons. The findings illustrate a robust interaction between intranganglionic neurons and glial cells that involve two way signals, features that may be critical for both regenerative responses and ongoing maintenance.

  3. Dark Material on Planetary Satellites and Rings

    NASA Technical Reports Server (NTRS)

    Cruikshank, Dale P.; DeVincenzi, Donald L. (Technical Monitor)

    1999-01-01

    Material of low albedo covers the surfaces, and in some cases constitutes the surfaces, of many planetary satellites. The low mean densities and water ice absorption bands detected in the spectra of some of these bodies show that they are fundamentally icy, but other bodies contain substantial fractions of rocky material. If we define three arbitrary albedo categories ranging from very low to very high, we find that there are many examples in each group.

  4. Analysis of laser jamming to satellite-based detector

    NASA Astrophysics Data System (ADS)

    Wang, Si-wen; Guo, Li-hong; Guo, Ru-hai

    2009-07-01

    The reconnaissance satellite, communication satellite and navigation satellite used in the military applications have played more and more important role in the advanced technique wars and already become the significant support and aid system for military actions. With the development of all kinds of satellites, anti-satellite laser weapons emerge as the times require. The experiments and analyses of laser disturbing CCD (charge coupled detector) in near ground have been studied by many research groups, but their results are not suitable to the case that using laser disturbs the satellite-based detector. Because the distance between the satellite-based detector and the ground is very large, it is difficult to damage it directly. However the optical receive system of satellite detector has large optical gain, so laser disturbing satellite detector is possible. In order to determine its feasibility, the theoretical analyses and experimental study are carried out in the paper. Firstly, the influence factors of laser disturbing satellite detector are analyzed in detail, which including laser power density on the surface of the detector after long distance transmission, and laser power density threshold for disturbing etc. These factors are not only induced by the satellite orbit, but dependence on the following parameters: laser average power in the ground, laser beam quality, tracing and aiming precision and atmospheric transmission. A calculation model is developed by considering all factors which then the power density entering into the detector can be calculated. Secondly, the laser disturbing experiment is performed by using LD (laser diode) with the wavelength 808 nm disturbing CCD 5 kilometer away, which the disturbing threshold value is obtained as 3.55×10-4mW/cm2 that coincides with other researcher's results. Finally, using the theoretical model, the energy density of laser on the photosensitive surface of MSTI-3 satellite detector is estimated as about 100m

  5. An abundant population of small irregular satellites around Jupiter.

    PubMed

    Sheppard, Scott S; Jewitt, David C

    2003-05-15

    Irregular satellites have eccentric orbits that can be highly inclined or even retrograde relative to the equatorial planes of their planets. These objects cannot have formed by circumplanetary accretion, unlike the regular satellites that follow uninclined, nearly circular and prograde orbits. Rather, they are probably products of early capture from heliocentric orbits. Although the capture mechanism remains uncertain, the study of irregular satellites provides a window on processes operating in the young Solar System. Families of irregular satellites recently have been discovered around Saturn (thirteen members, refs 6, 7), Uranus (six, ref. 8) and Neptune (three, ref. 9). Because Jupiter is closer than the other giant planets, searches for smaller and fainter irregular satellites can be made. Here we report the discovery of 23 new irregular satellites of Jupiter, so increasing the total known population to 32. There are five distinct satellite groups, each dominated by one relatively large body. The groups were most probably produced by collisional shattering of precursor objects after capture by Jupiter.

  6. An abundant population of small irregular satellites around Jupiter.

    PubMed

    Sheppard, Scott S; Jewitt, David C

    2003-05-15

    Irregular satellites have eccentric orbits that can be highly inclined or even retrograde relative to the equatorial planes of their planets. These objects cannot have formed by circumplanetary accretion, unlike the regular satellites that follow uninclined, nearly circular and prograde orbits. Rather, they are probably products of early capture from heliocentric orbits. Although the capture mechanism remains uncertain, the study of irregular satellites provides a window on processes operating in the young Solar System. Families of irregular satellites recently have been discovered around Saturn (thirteen members, refs 6, 7), Uranus (six, ref. 8) and Neptune (three, ref. 9). Because Jupiter is closer than the other giant planets, searches for smaller and fainter irregular satellites can be made. Here we report the discovery of 23 new irregular satellites of Jupiter, so increasing the total known population to 32. There are five distinct satellite groups, each dominated by one relatively large body. The groups were most probably produced by collisional shattering of precursor objects after capture by Jupiter. PMID:12748634

  7. Effects of specific multi-nutrient enriched diets on cerebral metabolism, cognition and neuropathology in AβPPswe-PS1dE9 mice.

    PubMed

    Jansen, Diane; Zerbi, Valerio; Arnoldussen, Ilse A C; Wiesmann, Maximilian; Rijpma, Anne; Fang, Xiaotian T; Dederen, Pieter J; Mutsaers, Martina P C; Broersen, Laus M; Lütjohann, Dieter; Miller, Malgorzata; Joosten, Leo A B; Heerschap, Arend; Kiliaan, Amanda J

    2013-01-01

    Recent studies have focused on the use of multi-nutrient dietary interventions in search of alternatives for the treatment and prevention of Alzheimer's disease (AD). In this study we investigated to which extent long-term consumption of two specific multi-nutrient diets can modulate AD-related etiopathogenic mechanisms and behavior in 11-12-month-old AβPPswe-PS1dE9 mice. Starting from 2 months of age, male AβPP-PS1 mice and wild-type littermates were fed either a control diet, the DHA+EPA+UMP (DEU) diet enriched with uridine monophosphate (UMP) and the omega-3 fatty acids docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), or the Fortasyn® Connect (FC) diet enriched with the DEU diet plus phospholipids, choline, folic acid, vitamins and antioxidants. We performed behavioral testing, proton magnetic resonance spectroscopy, immunohistochemistry, biochemical analyses and quantitative real-time PCR to gain a better understanding of the potential mechanisms by which these multi-nutrient diets exert protective properties against AD. Our results show that both diets were equally effective in changing brain fatty acid and cholesterol profiles. However, the diets differentially affected AD-related pathologies and behavioral measures, suggesting that the effectiveness of specific nutrients may depend on the dietary context in which they are provided. The FC diet was more effective than the DEU diet in counteracting neurodegenerative aspects of AD and enhancing processes involved in neuronal maintenance and repair. Both diets elevated interleukin-1β mRNA levels in AβPP-PS1 and wild-type mice. The FC diet additionally restored neurogenesis in AβPP-PS1 mice, decreased hippocampal levels of unbound choline-containing compounds in wild-type and AβPP-PS1 animals, suggesting diminished membrane turnover, and decreased anxiety-related behavior in the open field behavior. In conclusion, the current data indicate that specific multi-nutrient diets can influence AD

  8. Effects of specific multi-nutrient enriched diets on cerebral metabolism, cognition and neuropathology in AβPPswe-PS1dE9 mice.

    PubMed

    Jansen, Diane; Zerbi, Valerio; Arnoldussen, Ilse A C; Wiesmann, Maximilian; Rijpma, Anne; Fang, Xiaotian T; Dederen, Pieter J; Mutsaers, Martina P C; Broersen, Laus M; Lütjohann, Dieter; Miller, Malgorzata; Joosten, Leo A B; Heerschap, Arend; Kiliaan, Amanda J

    2013-01-01

    Recent studies have focused on the use of multi-nutrient dietary interventions in search of alternatives for the treatment and prevention of Alzheimer's disease (AD). In this study we investigated to which extent long-term consumption of two specific multi-nutrient diets can modulate AD-related etiopathogenic mechanisms and behavior in 11-12-month-old AβPPswe-PS1dE9 mice. Starting from 2 months of age, male AβPP-PS1 mice and wild-type littermates were fed either a control diet, the DHA+EPA+UMP (DEU) diet enriched with uridine monophosphate (UMP) and the omega-3 fatty acids docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), or the Fortasyn® Connect (FC) diet enriched with the DEU diet plus phospholipids, choline, folic acid, vitamins and antioxidants. We performed behavioral testing, proton magnetic resonance spectroscopy, immunohistochemistry, biochemical analyses and quantitative real-time PCR to gain a better understanding of the potential mechanisms by which these multi-nutrient diets exert protective properties against AD. Our results show that both diets were equally effective in changing brain fatty acid and cholesterol profiles. However, the diets differentially affected AD-related pathologies and behavioral measures, suggesting that the effectiveness of specific nutrients may depend on the dietary context in which they are provided. The FC diet was more effective than the DEU diet in counteracting neurodegenerative aspects of AD and enhancing processes involved in neuronal maintenance and repair. Both diets elevated interleukin-1β mRNA levels in AβPP-PS1 and wild-type mice. The FC diet additionally restored neurogenesis in AβPP-PS1 mice, decreased hippocampal levels of unbound choline-containing compounds in wild-type and AβPP-PS1 animals, suggesting diminished membrane turnover, and decreased anxiety-related behavior in the open field behavior. In conclusion, the current data indicate that specific multi-nutrient diets can influence AD

  9. Scientific analysis of satellite ranging data

    NASA Technical Reports Server (NTRS)

    Smith, David E.

    1994-01-01

    A network of satellite laser ranging (SLR) tracking systems with continuously improving accuracies is challenging the modelling capabilities of analysts worldwide. Various data analysis techniques have yielded many advances in the development of orbit, instrument and Earth models. The direct measurement of the distance to the satellite provided by the laser ranges has given us a simple metric which links the results obtained by diverse approaches. Different groups have used SLR data, often in combination with observations from other space geodetic techniques, to improve models of the static geopotential, the solid Earth, ocean tides, and atmospheric drag models for low Earth satellites. Radiation pressure models and other non-conservative forces for satellite orbits above the atmosphere have been developed to exploit the full accuracy of the latest SLR instruments. SLR is the baseline tracking system for the altimeter missions TOPEX/Poseidon, and ERS-1 and will play an important role in providing the reference frame for locating the geocentric position of the ocean surface, in providing an unchanging range standard for altimeter calibration, and for improving the geoid models to separate gravitational from ocean circulation signals seen in the sea surface. However, even with the many improvements in the models used to support the orbital analysis of laser observations, there remain systematic effects which limit the full exploitation of SLR accuracy today.

  10. Communication satellite technology: State of the art and development opportunities

    NASA Technical Reports Server (NTRS)

    Woodford, J. B. (Compiler)

    1978-01-01

    Opportunities in communication satellite technology are identified and defined. Factors that tend to limit the ready availability of satellite communication to an increasingly wide group of users are evaluated. Current primary limitations on this wide utilization are the availability of frequency and/or synchronous equatorial satellite positions and the cost of individual user Earth terminals. The former could be ameliorated through the reuse of frequencies, the use of higher frequency bands, and the reduction of antenna side lobes. The latter limitation requires innovative hardware, design, careful system design, and large scale production.

  11. The Water Vapor Variability - Satellite/Sondes (WAVES) Field Campaigns

    NASA Technical Reports Server (NTRS)

    Whiteman, D. N.; Adam, M.; Barnet, C.; Bojkov, B.; Delgado, R.; Demoz, B.; Fitzgibbon, J.; Forno, R.; Herman, R.; Hoff, E.; Joseph, E.; Landulfo, E.; McCann, K.; McGee, T.; Miloshevich, L.; Restrepo, I.; Schmidlin, F. J.; Taubman, B.; Thompson, A.; Twigg, L.; Venable, D.; Vomel, H.; Walthall, C.

    2008-01-01

    Three NASA-funded field campaigns have been hosted at the Howard University Research Campus in Beltsville, MD. In each of the years 2006, 2007 and 2008, WAVES field campaigns have coordinated ozonesonde launches, lidar operations and other measurements with A-train satellite overpasses for the purposes of satellite validation. The unique mix of measurement systems, physical location and the interagency, international group of researchers and students has permitted other objectives, such as mesoscale meteorological studies, to be addressed as well. We review the goals and accomplishments of the three WAVES missions with the emphasis on the nonsatellite validation component of WAVES, as the satellite validation activities have been reported elsewhere.

  12. ACTS Satellite Telemammography Network Experiments

    NASA Technical Reports Server (NTRS)

    Kachmar, Brian A.; Kerczewski, Robert J.

    2000-01-01

    The Satellite Networks and Architectures Branch of NASA's Glenn Research Center has developed and demonstrated several advanced satellite communications technologies through the Advanced Communications Technology Satellite (ACTS) program. One of these technologies is the implementation of a Satellite Telemammography Network (STN) encompassing NASA Glenn, the Cleveland Clinic Foundation. the University of Virginia, and the Ashtabula County Medical Center. This paper will present a look at the STN from its beginnings to the impact it may have on future telemedicine applications. Results obtained using the experimental ACTS satellite demonstrate the feasibility of Satellite Telemammography. These results have improved teleradiology processes and mammography image manipulation, and enabled advances in remote screening methodologies. Future implementation of satellite telemammography using next generation commercial satellite networks will be explored. In addition, the technical aspects of the project will be discussed, in particular how the project has evolved from using NASA developed hardware and software to commercial off the shelf (COTS) products. Development of asymmetrical link technologies was an outcome of this work. Improvements in the display of digital mammographic images, better understanding of end-to-end system requirements, and advances in radiological image compression were achieved as a result of the research. Finally, rigorous clinical medical studies are required for new technologies such as digital satellite telemammography to gain acceptance in the medical establishment. These experiments produced data that were useful in two key medical studies that addressed the diagnostic accuracy of compressed satellite transmitted digital mammography images. The results of these studies will also be discussed.

  13. Mobile satellite service communications tests using a NASA satellite

    NASA Technical Reports Server (NTRS)

    Chambers, Katherine H.; Koschmeder, Louis A.; Hollansworth, James E.; ONeill, Jack; Jones, Robert E.; Gibbons, Richard C.

    1995-01-01

    Emerging applications of commercial mobile satellite communications include satellite delivery of compact disc (CD) quality radio to car drivers who can select their favorite programming as they drive any distance; transmission of current air traffic data to aircraft; and handheld communication of data and images from any remote corner of the world. Experiments with the enabling technologies and tests and demonstrations of these concepts are being conducted before the first satellite is launched by utilizing an existing NASA spacecraft.

  14. Faint dwarfs in nearby groups

    SciTech Connect

    Speller, Ryan; Taylor, James E. E-mail: taylor@uwaterloo.ca

    2014-06-20

    The number and distribution of dwarf satellite galaxies remain a critical test of cold dark matter-dominated structure formation on small scales. Until recently, observational information about galaxy formation on these scales has been limited mainly to the Local Group. We have searched for faint analogues of Local Group dwarfs around nearby bright galaxies, using a spatial clustering analysis of the photometric catalog of the Sloan Digital Sky Survey (SDSS) Data Release 8. Several other recent searches of SDSS have detected clustered satellite populations down to Δm{sub r} ≡ (m{sub r,} {sub sat} – m{sub r,} {sub main}) ∼ 6-8, using photometric redshifts to reduce background contamination. SDSS photometric redshifts are relatively imprecise, however, for faint and nearby galaxies. Instead, we use angular size to select potential nearby dwarfs and consider only the nearest isolated bright galaxies as primaries. As a result, we are able to detect an excess clustering signal from companions down to Δm{sub r} = 12, 4 mag fainter than most recent studies. We detect an overdensity of objects at separations <400 kpc, corresponding to about 4.6 ± 0.5 satellites per central galaxy, consistent with the satellite abundance expected from the Local Group, given our selection function. Although the sample of satellites detected is incomplete by construction, since it excludes the least and most compact dwarfs, this detection provides a lower bound on the average satellite luminosity function, down to luminosities corresponding to the faintest ''classical'' dwarfs of the Local Group.

  15. Satellite-to-satellite system and orbital error estimates

    NASA Technical Reports Server (NTRS)

    Schmid, P. E.; Argentiero, P. D.; Vonbun, F. O.

    1976-01-01

    Satellite-to-satellite tracking and orbit computation accuracy is evaluated on the basis of data obtained from near earth spacecraft via the geostationary ATS-6. The near earth spacecraft involved are Apollo-Soyuz, GEOS-3, and NIMBUS-6. In addition ATS-6 is being tracked by a new scheme wherein a single ground transmitter interrogates several ground based transponders via ATS-6 to achieve the precision geostationary orbits essential in satellite-to-satellite orbit computation. Also one way Doppler data is being recorded aboard NIMBUS-6 to determine the position of meteorological platforms. Accuracy assessments associated with the foregoing mission related experiments are discussed.

  16. Nano-Satellite Avionics

    NASA Technical Reports Server (NTRS)

    Culver, Harry

    1999-01-01

    Abstract NASA's Goddard Space Flight Center (GSFC) is currently developing a new class of satellites called the nano-satellite (nano-sat). A major objective of this development effort is to provide the technology required to enable a constellation of tens to hundreds of nano-satellites to make both remote and in-situ measurements from space. The Nano-sat will be a spacecraft weighing a maximum of 10 kg, including the propellant mass, and producing at least 5 Watts of power to operate the spacecraft. The electronics are required to survive a total radiation dose rate of 100 krads for a mission lifetime of two years. There are many unique challenges that must be met in order to develop the avionics for such a spacecraft. The first challenge is to develop an architecture that will operate on the allotted 5 Watts and meet the diverging requirements of multiple missions. This architecture will need to incorporate a multitude of new advanced microelectronic technologies. The microelectronics developed must be a modular and scalable packaging of technology to solve the problem of developing a solution to both reduce cost and meet the requirements of various missions. This development will utilize the most cost effective approach, whether infusing commercially driven semiconductor devices into spacecraft applications or partnering with industry to design and develop low cost, low power, low mass, and high capacity data processing devices. This paper will discuss the nano-sat architecture and the major technologies that will be developed. The major technologies that will be covered include: (1) Light weight Low Power Electronics Packaging, (2) Radiation Hard/Tolerant, Low Power Processing Platforms, (3) High capacity Low Power Memory Systems (4) Radiation Hard reconfiguragble field programmable gate array (rFPGA)

  17. Satellite attitude control simulations

    NASA Technical Reports Server (NTRS)

    Debra, D. B.; Powell, J. D.

    1973-01-01

    Work was conducted to develop an extremely low drift rate gyroscope and a very precise star tracker. A proposed relativity satellite will measure very accurately the theoretically predicted 'relativistic' precession of the gyroscope relative to an inertial reference frame provided by the star tracker. Aspects of precision spinning attitude control are discussed together with questions of gyro operation, and the hopping mode for lunar transportation. For the attitude control system of the lunar hopper, a number of control laws were investigated. The studies indicated that some suboptimal controls should be adequate for the system.

  18. X-ray satellite

    NASA Technical Reports Server (NTRS)

    1985-01-01

    An overview of the second quarter 1985 development of the X-ray satellite project is presented. It is shown that the project is proceeding according to plan and that the projected launch date of September 9, 1987 is on schedule. An overview of the work completed and underway on the systems, subsystems, payload, assembly, ground equipment and interfaces is presented. Problem areas shown include cost increases in the area of focal instrumentation, the star sensor light scattering requirements, and postponements in the data transmission subsystems.

  19. LDEF satellite radiation study

    NASA Technical Reports Server (NTRS)

    Armstrong, T. W.; Colborn, B. L.

    1994-01-01

    Some early results are summarized from a program under way to utilize LDEF satellite data for evaluating and improving current models of the space radiation environment in low earth orbit. Reported here are predictions and comparisons with some of the LDEF dose and induced radioactivity data, which are used to check the accuracy of current models describing the magnitude and directionality of the trapped proton environment. Preliminary findings are that the environment models underestimate both dose and activation from trapped protons by a factor of about two, and the observed anisotropy is higher than predicted.

  20. The Galilean Satellites

    NASA Technical Reports Server (NTRS)

    1998-01-01

    This composite includes the four largest moons of Jupiter which are known as the Galilean satellites. The Galilean satellites were first seen by the Italian astronomer Galileo Galilei in 1610. Shown from left to right in order of increasing distance from Jupiter, Io is closest, followed by Europa, Ganymede, and Callisto.

    The order of these satellites from the planet Jupiter helps to explain some of the visible differences among the moons. Io is subject to the strongest tidal stresses from the massive planet. These stresses generate internal heating which is released at the surface and makes Io the most volcanically active body in our solar system. Europa appears to be strongly differentiated with a rock/iron core, an ice layer at its surface, and the potential for local or global zones of water between these layers. Tectonic resurfacing brightens terrain on the less active and partially differentiated moon Ganymede. Callisto, furthest from Jupiter, appears heavily cratered at low resolutions and shows no evidence of internal activity.

    North is to the top of this composite picture in which these satellites have all been scaled to a common factor of 10 kilometers (6 miles) per picture element.

    The Solid State Imaging (CCD) system aboard NASA's Galileo spacecraft acquired the Io and Ganymede images in June 1996, the Europa images in September 1996, and the Callisto images in November 1997.

    Launched in October 1989, the spacecraft's mission is to conduct detailed studies of the giant planet, its largest moons and the Jovian magnetic environment. The Jet Propulsion Laboratory, Pasadena, CA, manages the mission for NASA's Office of Space Science, Washington, DC.

    The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).

    This image and other images and data received from Galileo are posted on the World Wide Web

  1. The Galilean Satellites

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This composite includes the four largest moons of Jupiter which are known as the Galilean satellites. From left to right, the moons shown are Ganymede, Callisto, Io, and Europa. The Galilean satellites were first seen by the Italian astronomer Galileo Galilei in 1610. In order of increasing distance from Jupiter, Io is closest, followed by Europa, Ganymede, and Callisto.

    The order of these satellites from the planet Jupiter helps to explain some of the visible differences among the moons. Io is subject to the strongest tidal stresses from the massive planet. These stresses generate internal heating which is released at the surface and makes Io the most volcanically active body in our solar system. Europa appears to be strongly differentiated with a rock/iron core, an ice layer at its surface, and the potential for local or global zones of water between these layers. Tectonic resurfacing brightens terrain on the less active and partially differentiated moon Ganymede. Callisto, furthest from Jupiter, appears heavily cratered at low resolutions and shows no evidence of internal activity.

    North is to the top of this composite picture in which these satellites have all been scaled to a common factor of 10 kilometers (6 miles) per picture element.

    The Solid State Imaging (CCD) system aboard NASA's Galileo spacecraft obtained the Io and Ganymede images in June 1996, while the Europa images were obtained in September 1996. Because Galileo focuses on high resolution imaging of regional areas on Callisto rather than global coverage, the portrait of Callisto is from the 1979 flyby of NASA's Voyager spacecraft.

    Launched in October 1989, the spacecraft's mission is to conduct detailed studies of the giant planet, its largest moons and the Jovian magnetic environment. The Jet Propulsion Laboratory, Pasadena, CA, manages the mission for NASA's Office of Space Science, Washington, DC.

    This image and other images and data received from Galileo are posted on the World

  2. Satellite observations of contrails

    NASA Astrophysics Data System (ADS)

    Mannstein, H.; Meyer, R.; Wendlimg, P.

    2003-04-01

    A direct human influence on cirrus coverage close to the tropopause is given by the contrails produced from air-traffic, which is currently increasing at approximately 7%/year. The infrared channels of the Advanced Very High Resolution Radiometer (AVHRR) onboard of the weather satellites of the NOAA series are used for the automated detection of linear contrails. Results from studies on contrail coverage and the resulting radiative impact over Europe, SE and E-Asia will be presented and compared to results from model calculations.

  3. LDEF Satellite Radiation Analyses

    NASA Technical Reports Server (NTRS)

    Armstrong, T. W.; Colborn, B. L.

    1996-01-01

    Model calculations and analyses have been carried out to compare with several sets of data (dose, induced radioactivity in various experiment samples and spacecraft components, fission foil measurements, and LET spectra) from passive radiation dosimetry on the Long Duration Exposure Facility (LDEF) satellite, which was recovered after almost six years in space. The calculations and data comparisons are used to estimate the accuracy of current models and methods for predicting the ionizing radiation environment in low earth orbit. The emphasis is on checking the accuracy of trapped proton flux and anisotropy models.

  4. Tethered satellite system

    NASA Technical Reports Server (NTRS)

    Sisson, J.

    1986-01-01

    A reusable system is to be developed to enable a variety of scientific investigations to be accomplished from the shuttle, considering the use of a tethered system with manual or automated control, deployment of a satellite toward or away from the Earth, up to 100 km, and conducting or nonconducting tether. Experiments and scientific investigations are to be performed using the tether system for applications such as magnetometry, electrodynamics, atmospheric science, and chemical release. A program is being implemented as a cooperative U.S./Italian activity. The proposed systems, investigations, and the program are charted and briefly discussed.

  5. Radio broadcasting via satellite

    NASA Astrophysics Data System (ADS)

    Helm, Neil R.; Pritchard, Wilbur L.

    1990-10-01

    Market areas offering potential for future narrowband broadcast satellites are examined, including international public diplomacy, government- and advertising-supported, and business-application usages. Technical issues such as frequency allocation, spacecraft types, transmission parameters, and radio receiver characteristics are outlined. Service and system requirements, advertising revenue, and business communications services are among the economic issues discussed. The institutional framework required to provide an operational radio broadcast service is studied, and new initiatives in direct broadcast audio radio systems, encompassing studies, tests, in-orbit demonstrations of, and proposals for national and international commercial broadcast services are considered.

  6. Future communications satellite applications

    NASA Technical Reports Server (NTRS)

    Bagwell, James W.

    1992-01-01

    The point of view of the research is made through the use of viewgraphs. It is suggested that future communications satellite applications will be made through switched point to point narrowband communications. Some characteristics of which are as follows: small/low cost terminals; single hop communications; voice compatible; full mesh networking; ISDN compatible; and possible limited use of full motion video. Some target applications are as follows: voice/data networks between plants and offices in a corporation; data base networking for commercial and science users; and cellular radio internodal voice/data networking.

  7. Comparison of satellite theories

    NASA Technical Reports Server (NTRS)

    Hertz, H. G.

    1972-01-01

    The accuracy of five mathematical models in computing a nominal orbit for the Vanguard 2 satellite by using a position velocity vector is considered. Either numerical integration or analytical theories are used in all models as well as the same force model that corresponds to a potential with the zonal harmonics to order four. The amounts of spread in the values of the total energy and the z-component of the angular momentum for a set of times are considered as measures of accuracy.

  8. A geopause satellite system concept

    NASA Technical Reports Server (NTRS)

    Siry, J. W.

    1971-01-01

    A typical Geopause satellite orbit has a 14 hour period, a mean height of about 4.6 earth radii, and is nearly circular, polar, and normal to the ecliptic. At this height only a relatively few gravity terms have uncertainties corresponding to orbital perturbations above the decimeter level. The orbit is at the geopotential boundary, the geopause. The few remaining environmental quantities which may be significant can be determined by means of orbit analysis and accelerometers. The Geopause satellite system also provides the tracking geometry and coverage needed for determining the orbit, the tracking system biases and the station locations. Five or more fundamental stations well distributed in longitude can view Geopause over the North Pole. Geopause also provides the basic capability for satellite-to-satellite tracking of drag-free satellites for mapping the gravity field and altimeter satellites for surveying the sea surface topography.

  9. TDRSS Augmentation System for Satellites

    NASA Technical Reports Server (NTRS)

    Heckler, Gregory W.; Gramling, Cheryl; Valdez, Jennifer; Baldwin, Philip

    2016-01-01

    In 2015, NASA Goddard Space Flight Center (GSFC) reinvigorated the development of the TDRSS Augmentation Service for Satellites (TASS). TASS is a global, space-based, communications and navigation service for users of Global Navigation Satellite Systems(GNSS) and the Tracking and Data Relay Satellite System (TDRSS). TASS leverages the existing TDRSS to provide an S-band beacon radio navigation and messaging source to users at orbital altitudes 1400 km and below.

  10. Ionospheric limitations to time transfer by satellite

    NASA Technical Reports Server (NTRS)

    Knowles, S. H.

    1983-01-01

    The ionosphere can contribute appreciable group delay and phase change to radio signals traversing it; this can constitute a fundamental limitation to the accuracy of time and frequency measurements using satellites. Because of the dispersive nature of the ionosphere, the amount of delay is strongly frequency-dependent. Ionospheric compensation is necessary for the most precise time transfer and frequency measurements, with a group delay accuracy better than 10 nanoseconds. A priori modeling is not accurate to better than 25%. The dual-frequency compensation method holds promise, but has not been rigorously experimentally tested. Irregularities in the ionosphere must be included in the compensation process.

  11. Baseband Processor for Communication Satellites

    NASA Technical Reports Server (NTRS)

    Jirberg, Russell J.; Armstrong, Patrick C.

    1987-01-01

    Baseband processing (BBP) system for advanced satellite communications successfully demonstrated. Provides increased data capacity through frequency-reusing multibeam antenna systems, using time-division multiple access (TDMA) and onboard satellite switching. Large numbers of thin-route trunking stations and user-based Earth terminals handled efficiently by satellite baseband switching. With BBP system, satellite routes data messages individually among locations anywhere in continental United States. Processes, controls, and routes message traffic among users. Time-division multiple access and baseband switching used.

  12. Satellite communication for public services

    NASA Technical Reports Server (NTRS)

    Cooper, R. S.; Redisch, W. N.

    1977-01-01

    Public service programs using NASA's ATS-6 and CTS satellites are discussed. Examples include the ATS-6 Health and Education Telecommunications experimental program and the use of CTS to enable students in one university to take courses presented at another distant university. Possible applications of satellite communication systems to several areas of public service are described, and economic and political obstacles hindering the implementation of these programs are considered. It is suggested that a federally sponsored program demonstrating the utility of satellites accomodating a large number of small terminals is needed to encourage commercial satellite operations.

  13. Communications satellite systems capacity analysis

    NASA Technical Reports Server (NTRS)

    Browne, L.; Hines, T.; Tunstall, B.

    1982-01-01

    Analog and digital modulation techniques are compared with regard to efficient use of the geostationary orbit by communications satellites. Included is the definition of the baseline systems (both space and ground segments), determination of interference susceptibility, calculation of orbit spacing, and evaluation of relative costs. It is assumed that voice or TV is communicated at 14/11 GHz using either FM or QPSK modulation. Both the Fixed-Satellite Service and the Broadcasting-Satellite Service are considered. For most of the cases examined the digital approach requires a satellite spacing less than or equal to that required by the analog approach.

  14. Profiler/satellite interference analysis

    NASA Astrophysics Data System (ADS)

    Chadwick, R. B.

    1987-02-01

    An engineering analysis of potential radio interference between the Wind Profiler Demonstration Network and three NOAA satellite-based systems is presented. These three systems are: Geostationary Operational Environmental Satellite (GOES) system, the Search and Rescue Satellite (SARSAT) system, and the TIROS series Data Collection System (TDCS). The Profiler considered in this analysis is the UHF Wind Profiler to be supplied by Sperry Corporation under a contract awarded June 1986. The analysis is based on the interference-to-noise ratio at the satellite receiver. Several engineering changes have been made to the original contract to reduce potential interference. The effects of these changes are presented.

  15. NOAA's NESDIS operational satellite oceanography

    NASA Astrophysics Data System (ADS)

    Bayler, E.; Chang, P.; Cheney, R.; Clark, D.; Hughes, K.; Strong, A.

    2003-04-01

    Satellite oceanography within the National Oceanic and Atmospheric Administration's (NOAA) National Environmental Satellite, Data, and Information Service (NESDIS) focuses on observation retrieval and applications to address the NOAA missions of environmental assessment, prediction, and stewardship. The satellite oceanography division encompasses three functional areas: satellite ocean sensors, ocean dynamics/ data assimilation, and marine ecosystems / climate. The breadth of scientific investigation includes sea-surface temperature, sea-surface height, sea-surface height, sea-surface roughness, ocean color, ocean surface winds, sea ice, data assimilation, and operational oceanography. The primary objective is to transition research to operations. This overview of operational oceanography within NOAA's NESDIS provides insight into the capabilities, products, and services.

  16. Trends in mobile satellite communication

    NASA Technical Reports Server (NTRS)

    Johannsen, Klaus G.; Bowles, Mike W.; Milliken, Samuel; Cherrette, Alan R.; Busche, Gregory C.

    1993-01-01

    Ever since the U.S. Federal Communication Commission opened the discussion on spectrum usage for personal handheld communication, the community of satellite manufacturers has been searching for an economically viable and technically feasible satellite mobile communication system. Hughes Aircraft Company and others have joined in providing proposals for such systems, ranging from low to medium to geosynchronous orbits. These proposals make it clear that the trend in mobile satellite communication is toward more sophisticated satellites with a large number of spot beams and onboard processing, providing worldwide interconnectivity. Recent Hughes studies indicate that from a cost standpoint the geosynchronous satellite (GEOS) is most economical, followed by the medium earth orbit satellite (MEOS) and then by the low earth orbit satellite (LEOS). From a system performance standpoint, this evaluation may be in reverse order, depending on how the public will react to speech delay and collision. This paper discusses the trends and various mobile satellite constellations in satellite communication under investigation. It considers the effect of orbital altitude and modulation/multiple access on the link and spacecraft design.

  17. Business Use of Satellite Communications.

    ERIC Educational Resources Information Center

    Edelson, Burton I.; Cooper, Robert S.

    1982-01-01

    Reviews business communications development and discusses business applications of satellite communications, system technology, and prospects for future developments in digital transmission systems. (JN)

  18. Asymmetric Warfare: M31 and its Satellites

    NASA Astrophysics Data System (ADS)

    Fardal, M.

    2010-06-01

    Photometric surveys of M31's halo vividly illustrate the wreckage caused by hierarchical galaxy formation. Several of M31's satellites are being disrupted by M31's tidal field, among them M33 and And I, while other tidal structures are the corpses of satellites already destroyed. The extent to which M31's satellites have left battle scars upon it is unknown; to answer this we need accurate orbits and masses of the perturbers. I focus here on M31's 150-kpc-long Giant Southern Stream (GSS) as an example of how these can be determined even in the absence of a visible progenitor. Comparing N-body models to photometric and spectroscopic data, I find this stream resulted from the disruption of a large satellite galaxy by a close passage about 750 Myr ago. The GSS is connected to several other debris structures in M31's halo. Bayesian sampling of the simulations estimates the progenitor's initial mass as M* = 109.5±0.2 Msun, showing it was one of the most massive Local Group galaxies until quite recently. The stream model constrains M31's halo mass to be ( 1.8 ± 0.5 ) × 1012 Msun. While these small uncertainties neglect several important degrees of freedom, they are likely to remain good even with a more complete model. Future work on M31 satellites and streams will provide independent constraints on M31's mass and reveal the shared history of M31 and its halo components.

  19. The power relay satellite

    NASA Astrophysics Data System (ADS)

    Glaser, Peter E.

    The availability and use of renewable energy sources compatible with reducing risks to the global environment are key to sustainable development. Large-scale, renewable energy resources at undeveloped or underutilized sites are potentially available on several continents. The Power Relay Satellite (PRS) concept has the potential to access these remote energy resources by coupling primary electricity generation from terrestrial transmission lines. A global PRS network can be envisioned to provide a high degree of flexibility for supplying energy demands worldwide with wireless power transmitted from sites on Earth to geosynchronous orbit and then reflected to receivers interfacing with terrestrial power transmision networks. Past developments in wireless power transmission (WPT) are reviewed and recent successful results are noted. The origins of the PRS concept, and a possible configuration are discussed, principles of WPT at microwave frequencies, functional requirements, and system design contraints are outlined, and space transportation concepts presented. PRS assessments including applicable technologies, economic projections, and societal issues are highlighted. It is concluded that the PRS provides a promising option to access renewable resources at great distances from major markets, and represents an important stage in the future development in the future of solar power satellites.

  20. GSICS Satellite Intercalibration Products

    NASA Astrophysics Data System (ADS)

    Bali, M.; Flynn, L. E.

    2015-12-01

    Monitoring satellite instrument measurements (Top of Atmosphere radiances) while they are orbiting by comparing them with in-orbit stable references has emerged as a key component of ensuring quality (the stability and accuracy) of their measurements and correcting any biases that emerge during the mission. In 2006 the World Meteorological Organization (WMO) and the CGMS together initiated the Gobal Space Based Inter-Calibration System (GSICS,gsics.wmo.int) with the aim of monitoring the quality of measurement from satellite instruments launched by member including NASA, NOAA, EUMETSAT, ISRO CMA KMA CNES. In recent years, GSICS, via collaboration among member agencies across nations has successfully monitored instrument records for both GEO (GOES, SEVIRI, MTSAT) and LEO (AVHRR) based instruments by comparing them to in-orbit references such as IASI, AIRS and MODIS. The cross comparison products undergo stringent quality checks and standarizations and a scientific review of the theoretical bases and are assigned a GSICS maturity level. The accepted products are distributed freely as GSICS correction products. These products have wide applications. The goal of the presentation is to introduce GSICS cross calibration products and demonstrate their applications in developing products such as Fundamental Climate Data Records (FCDRs), evaluating Spectral Response Function status, and providing bias corrections. The impact of the GSICS bias corrections on retrieval of downstream variables such as Cloud Height Sea Surface Temperature will be one component of the presentation.

  1. The power relay satellite

    SciTech Connect

    Glaser, P.E.

    1994-12-31

    The availability and use of renewable energy sources compatible with reducing risks to the global environment are key to sustainable development. Large-scale, renewable energy resources at undeveloped or underutilized sites are potentially available on several continents. The Power Relay Satellite (PRS) concept has the potential to access these remote energy resources by coupling primary electricity generation from terrestrial transmission lines. A global PRS network can be envisioned to provide a high degree of flexibility for supplying energy demands worldwide with wireless power transmitted from sites on Earth to geosynchronous orbit and then reflected to receivers interfacing with terrestrial power transmision networks. Past developments in wireless power transmission (WPT) are reviewed and recent successful results are noted. The origins of the PRS concept, and a possible configuration are discussed, principles of WPT at microwave frequencies, functional requirements, and system design contraints are outlined, and space transportation concepts presented. PRS assessments including applicable technologies, economic projections, and societal issues are highlighted. It is concluded that the PRS provides a promising option to access renewable resources at great distances from major markets, and represents an important stage in the future development in the future of solar power satellites.

  2. Enceladus: a vanishing satellite

    NASA Astrophysics Data System (ADS)

    Czechowski, Leszek

    2014-05-01

    Enceladus, a satellite of Saturn, is the smallest celestial body in the Solar System where volcanic activity is observed. Every second, the mass of ~200 kg is ejecting into space. The size of the satellite directly after accretion (this body is referred here as proto-Enceladus) is unknown. It can be estimated in two ways. First, if the average mass outflow is equal to the present rate then the satellite's original mass was ~30% bigger than today. Second, we assume here that density of proto-Enceladus was equal to the present density of Mimas because they were formed in the same part of the nebula. Mimas is dead, so it preserves original composition. Both approaches give similar initial Enceladus' radius (~296 km) and its surface area (~1.1×106 km2). The present values are: 252 km and 7.99×105 km2. The loss of matter should lead to global compression of the crust. Typical effects of compression are: thrust faults, folding, and subduction. However, such forms are not dominant on Enceladus. We propose here special tectonic model that could explain this paradox. The volatiles escape from the hot region through the fractures forming plumes in the space. The loss of the volatiles results in a void, an instability, and motion of solid matter into hot region to fill the void in statu nascendi. The motion includes: Subsidence of the lithosphere of SPT. Flow of matter in the mantle. Motion of lithospheric plates adjacent to SPT towards the active region. If emerging void is being filled by the subsidence of SPT only, then the velocity of subsidence is ~0.05 mm·yr-1. However, all three types of motion are probably important, so the subsidence is slower but mantle flow and plates' motion also play a role in filling the void. Note that in our model reduction of the crust area is not a result of compression but it is a result of the plate sinking. Therefore the compressional surface features do not have to be dominant. Note also that we do not know the present age of the

  3. Satellite power system (SPS) public outreach experiment

    SciTech Connect

    McNeal, S.R.

    1980-12-01

    To improve the results of the Satellite Power System (SPS) Concept Development and Evaluation Program, an outreach experiment was conducted. Three public interest groups participated: the L-5 Society (L-5), Citizen's Energy Project (CEP), and the Forum for the Advancement of Students in Science and Technology (FASST). Each group disseminated summary information about SPS to approximately 3000 constituents with a request for feedback on the SPS concept. The objectives of the outreach were to (1) determine the areas of major concern relative to the SPS concept, and (2) gain experience with an outreach process for use in future public involvement. Due to the combined efforts of all three groups, 9200 individuals/organizations received information about the SPS concept. Over 1500 receipients of this information provided feedback. The response to the outreach effort was positive for all three groups, suggesting that the effort extended by the SPS Project Division to encourage an information exchange with the public was well received. The general response to the SPS differed with each group. The L-5 position is very much in favor of SPS; CEP is very much opposed and FASST is relatively neutral. The responses are analyzed, and from the responses some questions and answers about the satellite power system are presented in the appendix. (WHK)

  4. Gigabit Satellite Network for NASA's Advanced Communication Technology Satellite (ACTS)

    NASA Technical Reports Server (NTRS)

    Hoder, Douglas; Bergamo, Marcos

    1996-01-01

    The advanced communication technology satellite (ACTS) gigabit satellite network provides long-haul point-to-point and point-to-multipoint full-duplex SONET services over NASA's ACTS. at rates up to 622 Mbit/s (SONET OC-12), with signal quality comparable to that obtained with terrestrial fiber networks. Data multiplexing over the satellite is accomplished using time-division multiple access (TDMA) techniques coordinated with the switching and beam hopping facilities provided by ACTS. Transmissions through the satellite are protected with Reed-Solomon encoding. providing virtually error-free transmission under most weather conditions. Unique to the system are a TDMA frame structure and satellite synchronization mechanism that allow: (a) very efficient utilization of the satellite capacity: (b) over-the-satellite dosed-loop synchronization of the network in configurations with up to 64 ground stations: and (c) ground station initial acquisition without collisions with existing signalling or data traffic. The user interfaces are compatible with SONET standards, performing the function of conventional SONET multiplexers and. as such. can be: readily integrated with standard SONET fiber-based terrestrial networks. Management of the network is based upon the simple network management protocol (SNMP). and includes an over-the-satellite signalling network and backup terrestrial internet (IP-based) connectivity. A description of the ground stations is also included.

  5. Training Groups, Encounter Groups, Sensitivity Groups and Group Psychotherapy

    PubMed Central

    Gottschalk, Louis A.; Pattison, E. Mansell; Schafer, Donald W.

    1971-01-01

    Descriptions and comparison of group therapies and the new group procedures (training groups and sensitivity groups—an outgrowth of the so-called Laboratory Movement methods of the mid-1930's) have been provided for the better understanding of non-psychiatric physicians. A group leader must have proper training and must help his group in its search for its avowed goals, whether he is a group therapist, a sensitivity trainer, or anyone else interested in utilizing group processes. Those goals are either the therapeutic benefit of the individual, as defined in group psychotherapy, or a better understanding of how one functions in groups, as in T-groups or the other group processes in the area of sensitive living. All group situations contain powerful tools which must be handled with proper respect. When so handled by experienced leaders, the individuals involved can achieve their goals in these group experiences. PMID:18730582

  6. A classification system for virophages and satellite viruses.

    PubMed

    Krupovic, Mart; Kuhn, Jens H; Fischer, Matthias G

    2016-01-01

    Satellite viruses encode structural proteins required for the formation of infectious particles but depend on helper viruses for completing their replication cycles. Because of this unique property, satellite viruses that infect plants, arthropods, or mammals, as well as the more recently discovered satellite-like viruses that infect protists (virophages), have been grouped with other, so-called "sub-viral agents." For the most part, satellite viruses are therefore not classified. We argue that possession of a coat-protein-encoding gene and the ability to form virions are the defining features of a bona fide virus. Accordingly, all satellite viruses and virophages should be consistently classified within appropriate taxa. We propose to create four new genera - Albetovirus, Aumaivirus, Papanivirus, and Virtovirus - for positive-sense single-stranded (+) RNA satellite viruses that infect plants and the family Sarthroviridae, including the genus Macronovirus, for (+)RNA satellite viruses that infect arthopods. For double-stranded DNA virophages, we propose to establish the family Lavidaviridae, including two genera, Sputnikvirus and Mavirus.

  7. BRITE-PL: the first Polish scientific satellite

    NASA Astrophysics Data System (ADS)

    Orleanski, Piotr; Graczyk, Rafal; Rataj, Miroslaw; Schwarzenberg-Czerny, Aleksander; Zawistowski, Tomasz; Zee, Robert E.

    2010-09-01

    The participation in BRITE Consortium gives Poland the possibility to launch into space the first Polish scientific satellite. This paper presents the Polish technical contribution to the BRITE Program to be realized in two institutes of the Polish Academy of Sciences: Nicolaus Copernicus Astronomical Center and Space Research Center.. BRITE Constellation, short for "BRIght Target Explorer Constellation," is a group of up to six nano-satellites whose purpose is to photometrically measure low-level oscillations and temperature variations in the sky's 286 stars brighter than visual magnitude 3.5, with unprecedented precision and time sampling not achievable through terrestrial-based methods. The three-axis pointing performance (1 arc minute rms stability) of each BRITE satellite is a significant advancement over anything that has ever flown before on a nano-satellite and is an important factor that enables the high precision photometry mission. The paper summarizes the technical details of the BRITE satellite based on Generic Nanosatellite Bus from SFL/UTIAS. The first Polish satellite, BRITE -PL 1, will be a modified version of the original SFL design. The second Polish satellite, BRITE-PL 2, will include the significant changes to be implemented by SRC PAS.

  8. Satellite-Based Educational Services. Technical Memorandum.

    ERIC Educational Resources Information Center

    Operations Research, Inc., Silver Spring, MD.

    This memorandum contains engineering information relevant to the use of communication satellites for educational purposes. Information is provided for ground terminals as well as satellites. Satellite related issues addressed include: (1) expected life of service of various satellites, (2) constraints on the availability of the satellites, (3)…

  9. Sentinels in the Sky: Weather Satellites.

    ERIC Educational Resources Information Center

    Haynes, Robert

    This publication describes forecasting weather activity using satellites. Information is included on the development of weather satellites, the National Oceanic and Atmospheric Administration (NOAA) Satellite System (including the polar-orbiting satellites), and the Geostationary Operational Environmental Satellite (GOES). The publication…

  10. Group Counseling

    ERIC Educational Resources Information Center

    Mahler, Clarence A.

    1971-01-01

    This article reviews the major concerns of group counseling and differentiates among group guidance, group counseling, and group therapy. It also evaluates the research status of group counseling and presents implications for the future of this approach. Comment by Carl E. Thoresen follows. (Author)

  11. Newspaper Uses of Satellite Technology.

    ERIC Educational Resources Information Center

    Johns, David

    Replacing slower mail service, satellite transmission now gives the newspaper industry a practical and almost spontaneous method for sending all kinds of information to any newspaper across the country. Unlike other communication industries, newspapers did not begin to make widespread use of satellite technology until 1979, when government…

  12. Satellite (IRLS) tracking of elk

    NASA Technical Reports Server (NTRS)

    Buechner, H. K.

    1972-01-01

    The practicability of tracking free roaming animals in natural environments by satellite systems is reported. Satellite systems combine continuous tracking with simultaneous monitoring of physiological and environmental parameters through a combination of radio tracking and biotelemetric ground systems that lead to a better understanding of animal behavior and migration patterns.

  13. Satellites: Teaching Technology Looks Up

    ERIC Educational Resources Information Center

    Lewis, Philip

    1973-01-01

    A Satellite will beam career education programs to 56 rural junior high schools and 12 public broadcasting stations in eight Rocky Mountain States. Programing on health, drug education, and English as a second language will be beamed to Alaskan elementary schools. Satellite beamed programs to India are planned on improving occupations skills, food…

  14. Satellite Technology Demonstration; Final Report.

    ERIC Educational Resources Information Center

    Federation of Rocky Mountain States, Inc., Denver, CO.

    The goal of the Satellite Technology Demonstration project (STD) was to show the feasibility of a satellite-based media system for isolated, rural populations and to test and evaluate user acceptance and the cost of various delivery modes using a variety of materials. The STD amalgamated the resources of government, health, education, and…

  15. Drag-free satellite control

    NASA Technical Reports Server (NTRS)

    Debra, Daniel B.

    1989-01-01

    A drag-free satellite cancels the effect of external disturbances. Although the forces may be small, a satellite is disturbed by residual air drag, radiation pressure, micrometeorite impact, and other small forces that act on its surface disturbing its orbit, which is principally determined by the gravity field. In some missions, these small perturbations that make the satellite deviate from its purely gravitational orbit are limiting. An internal unsupported proof mass is shielded by the satellite from the external disturbances. The position of the shield (or the main part of the satellite) is measured with respect to the internal proof mass, and this information is used to actuate a propulsion system which moves the satellite to follow the proof mass. A drag-free control system is illustrated. Since the proof mass is shielded it follows a purely gravitational orbit - as does the satellite following it - hence the name drag-free satellite. The idea was conceived by Lange (1964) and has been applied to many mission studies since. In some cases, it is not necessary to cancel the disturbances, only to measure them so they may be taken into account. In such cases, an accelerometer may be a more suitable solution (for example, using the ONERA Cactus or the Bell Aerosystems MESA).

  16. A new satellite of saturn?

    PubMed

    Fountain, J W; Larson, S M

    1977-08-26

    Analysis of all available observations of faint objects near Saturn during the 1966 passage of the earth through the plane of Saturn's rings suggests the existence of at least one previously undiscovered satellite of Saturn. The data support the previously published orbit for Janus. These satellites may be major members of an extended ring.

  17. Radiocommunications for meteorological satellite systems

    NASA Technical Reports Server (NTRS)

    Walton, B. A.

    1975-01-01

    A general overview is presented of the spectrum utilization and frequency requirements of present and planned meteorological satellite programs. The sensors, and TIROS operational systems are discussed along with the Nimbus and Synchronous Meteorological Satellites. STORMSAT, SEASAT, and the Spacelab are briefly described.

  18. Capture-ejector satellites

    NASA Technical Reports Server (NTRS)

    Macconochie, I. O.; Eldred, C. H.; Martin, J. A.

    1983-01-01

    A satellite in the form of a large rotating rim which can be used to boost spacecraft from low-Earth orbit to higher orbits is described. The rim rotates in the plane of its orbit such that the lower portion of the rim is traveling at suborbital velocity, while the upper portion is travelling at greater than orbital velocity. Ascending spacecraft or payloads arrive at the lowest portion of the rim at suborbital velocities, where the payloads are released on a trajectory for higher orbits; descending payloads employ the reverse procedure. Electric thrusters placed on the rim maintain rim rotational speed and altitude. From the standpoint of currently known materials, the capture-ejector concept may be useful for relatively small velocity increments.

  19. The SPOT satellite

    NASA Astrophysics Data System (ADS)

    Fouquet, J.-P.

    1981-03-01

    The background, objectives and data products of the French SPOT remote sensing satellite system are presented. The system, which was developed starting in 1978 with the subsequent participation of Sweden and Belgium, is based on a standard multimission platform with associated ground control station and a mission-specific payload, which includes two High-Resolution Visible range instruments allowing the acquisition of stereoscopic views from different orbits. Mission objectives include the definition of future remote sensing systems, the compilation of a cartographic and resources data base, the study of species discrimination and production forecasting based on frequent access and off-nadir viewing, the compilation of a stereoscopic data base, and platform and instrument qualification, for possible applications in cartography, geology and agriculture. Standard data products will be available at three levels of preprocessing: radiometric correction only, precision processing for vertical viewing, and cartographic quality processing.

  20. Satellite Rings Movie

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This brief movie clip (of which the release image is a still frame), taken by NASA's Cassini spacecraft as it approached Jupiter, shows the motions, over a 16 hour-period, of two satellites embedded in Jupiter's ring. The moon Adrastea is the fainter of the two, and Metis the brighter. Images such as these will be used to refine the orbits of the two bodies.

    The movie was made from images taken during a 40-hour sequence of the Jovian ring on December 11, 2000.

    Cassini is a cooperative mission of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology in Pasadena, manages Cassini for NASA's Office of Space Science, Washington, D.C.

  1. Alaska's giant satellite network

    NASA Astrophysics Data System (ADS)

    Hills, A.

    1983-07-01

    The evolution and features of the Alaskan telecommunications network are described, with emphasis on the satellite links. The Alaskan terrain is rugged and largely unpopulated. Satcom V provides C-band (6/4 GHz) transmission with 24 transponders, each having a 40 MHz bandwidth. The Alascom company operated 105 4.5 m earth-based antennas for remote villages, which receive both telephone and television services. There are also 27 10-m dishes for regional and military applications and a 30 m dish, one of three dishes for links to the centerminous U.S. Currently, half the villages have private and business telephone communications facilities and 200 villages have access to two television stations, one educational, one entertainment. Teleconferencing is possible for government and educational purposes, and discussions are underway with NASA to establish a mobile radio communications capacity.

  2. Polar research from satellites

    NASA Technical Reports Server (NTRS)

    Thomas, Robert H.

    1991-01-01

    In the polar regions and climate change section, the topics of ocean/atmosphere heat transfer, trace gases, surface albedo, and response to climate warming are discussed. The satellite instruments section is divided into three parts. Part one is about basic principles and covers, choice of frequencies, algorithms, orbits, and remote sensing techniques. Part two is about passive sensors and covers microwave radiometers, medium-resolution visible and infrared sensors, advanced very high resolution radiometers, optical line scanners, earth radiation budget experiment, coastal zone color scanner, high-resolution imagers, and atmospheric sounding. Part three is about active sensors and covers synthetic aperture radar, radar altimeters, scatterometers, and lidar. There is also a next decade section that is followed by a summary and recommendations section.

  3. Enceladus: a vanishing satellite

    NASA Astrophysics Data System (ADS)

    Czechowski, Leszek

    Enceladus, a satellite of Saturn, is the smallest celestial body in the Solar System where volcanic activity is observed. Every second, the mass of 200 kg is ejecting into space. The size of the satellite directly after accretion (this body is referred here as proto-Enceladus) is unknown. It can be estimated in two ways. First, if the average mass outflow is equal to the present rate then the satellite’s original mass was 30% bigger than today. Second, we assume here that density of proto-Enceladus was equal to the present density of Mimas because they were formed in the same part of the nebula. Mimas is dead, so it preserves original composition. Both approaches give similar initial Enceladus’ radius ( 296 km) and its surface area ( 1.1×106 km2). The present values are: 252 km and 7.99×105 km2. The loss of matter should lead to global compression of the crust. Typical effects of compression are: thrust faults, folding, and subduction. However, such forms are not dominant on Enceladus. We propose here special tectonic model that could explain this paradox. The volatiles escape from the hot region through the fractures forming plumes in the space. The loss of the volatiles results in a void, an instability, and motion of solid matter into hot region to fill the void in statu nascendi. The motion includes: (i) Subsidence of the lithosphere of SPT. (ii) Flow of matter in the mantle. (iii) Motion of lithospheric plates adjacent to SPT towards the active region. If emerging void is being filled by the subsidence of SPT only, then the velocity of subsidence is 0.05 mm·yr-1. However, all three types of motion are probably important, so the subsidence is slower but mantle flow and plates’ motion also play a role in filling the void. Note that in our model reduction of the crust area is not a result of compression but it is a result of the plate sinking. Therefore the compressional surface features do not have to be dominant. Note also that we do not know the

  4. Satellite Power System (SPS)

    NASA Technical Reports Server (NTRS)

    Edler, H. G.

    1978-01-01

    Potential organizational options for a solar power satellite system (SPS) were investigated. Selection and evaluation criteria were determined to include timeliness, reliability, and adequacy to contribute meaningfully to the U.S. supply; political feasibility (both national and international); and cost effectiveness (including environmental and other external costs). Based on these criteria, four organizational alternatives appeared to offer reasonable promise as potential options for SPS. A large number of key issues emerged as being factors which would influence the final selection process. Among these issues were a variety having to do with international law, international institutions, environmental controls, economics, operational flexibility, congressional policies, commercial-vs-governmental ownership, national dedication, and national and operational stategic issues.

  5. Multipurpose satellite bus (MPS)

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The Naval Postgraduate School Advanced Design Project sponsored by the Universities Space Research Association Advanced Design Program is a multipurpose satellite bus (MPS). The design was initiated from a Statement of Work (SOW) developed by the Defense Advanced Research Projects Agency (DARPA). The SOW called for a 'proposal to design a small, low-cost, lightweight, general purpose spacecraft bus capable of accommodating any of a variety of mission payloads. Typical payloads envisioned include those associated with meteorological, communication, surveillance and tracking, target location, and navigation mission areas.' The design project investigates two dissimilar missions, a meteorological payload and a communications payload, mated with a single spacecraft bus with minimal modifications. The MPS is designed for launch aboard the Pegasus Air Launched Vehicle (ALV) or the Taurus Standard Small Launch Vehicle (SSLV).

  6. IIth AMS Conference on Satellite Meteorology and Oceanography.

    NASA Astrophysics Data System (ADS)

    Velden, Christopher; Digirolamo, Larry; Glackin, Mary; Hawkins, Jeffrey; Jedlovec, Gary; Lee, Thomas; Petty, Grant; Plante, Robert; Reale, Anthony; Zapotocny, John

    2002-11-01

    The American Meteorological Society (AMS) held its 11th Conference on Satellite Meteorology and Oceanography at the Monona Terrace Convention Center in Madison, Wisconsin, during 15-18 October 2001. The purpose of the conference, typically held every 18 months, is to promote a forum for AMS membership, international scientists, and student members to present and discuss the latest advances in satellite remote sensing for meteorological and oceanographical applications. This year, surrounded by inspirational designs by famed architect Frank Lloyd Wright, the meeting focused on several broad topics related to remote sensing from space, including environmental applications of land and oceanic remote sensing, climatology and long-term satellite data studies, operational applications, radiances and retrievals, and new technology and methods. A vision of an increasing convergence of satellite systems emerged that included operational and research satellite programs and interdisciplinary user groups.The conference also hosted NASA's Electronic Theater, which was presented to groups of middle and high school students totaling over 5500. It was truly a successful public outreach event. The conference banquet was held on the final evening, where a short tribute to satellite pioneer Verner Suomi was given by Joanne Simpson. Suomi was responsible for establishing the Space Science and Engineering Center at the University of Wisconsin in Madison.

  7. Data distribution satellite

    NASA Technical Reports Server (NTRS)

    Stevens, Grady H.

    1992-01-01

    The Data Distribution Satellite (DDS), operating in conjunction with the planned space network, the National Research and Education Network and its commercial derivatives, would play a key role in networking the emerging supercomputing facilities, national archives, academic, industrial, and government institutions. Centrally located over the United States in geostationary orbit, DDS would carry sophisticated on-board switching and make use of advanced antennas to provide an array of special services. Institutions needing continuous high data rate service would be networked together by use of a microwave switching matrix and electronically steered hopping beams. Simultaneously, DDS would use other beams and on board processing to interconnect other institutions with lesser, low rate, intermittent needs. Dedicated links to White Sands and other facilities would enable direct access to space payloads and sensor data. Intersatellite links to a second generation ATDRS, called Advanced Space Data Acquisition and Communications System (ASDACS), would eliminate one satellite hop and enhance controllability of experimental payloads by reducing path delay. Similarly, direct access would be available to the supercomputing facilities and national data archives. Economies with DDS would be derived from its ability to switch high rate facilities amongst users needed. At the same time, having a CONUS view, DDS would interconnect with any institution regardless of how remote. Whether one needed high rate service or low rate service would be immaterial. With the capability to assign resources on demand, DDS will need only carry a portion of the resources needed if dedicated facilities were used. Efficiently switching resources to users as needed, DDS would become a very feasible spacecraft, even though it would tie together the space network, the terrestrial network, remote sites, 1000's of small users, and those few who need very large data links intermittently.

  8. Advanced satellite communication system

    NASA Technical Reports Server (NTRS)

    Staples, Edward J.; Lie, Sen

    1992-01-01

    The objective of this research program was to develop an innovative advanced satellite receiver/demodulator utilizing surface acoustic wave (SAW) chirp transform processor and coherent BPSK demodulation. The algorithm of this SAW chirp Fourier transformer is of the Convolve - Multiply - Convolve (CMC) type, utilizing off-the-shelf reflective array compressor (RAC) chirp filters. This satellite receiver, if fully developed, was intended to be used as an on-board multichannel communications repeater. The Advanced Communications Receiver consists of four units: (1) CMC processor, (2) single sideband modulator, (3) demodulator, and (4) chirp waveform generator and individual channel processors. The input signal is composed of multiple user transmission frequencies operating independently from remotely located ground terminals. This signal is Fourier transformed by the CMC Processor into a unique time slot for each user frequency. The CMC processor is driven by a waveform generator through a single sideband (SSB) modulator. The output of the coherent demodulator is composed of positive and negative pulses, which are the envelopes of the chirp transform processor output. These pulses correspond to the data symbols. Following the demodulator, a logic circuit reconstructs the pulses into data, which are subsequently differentially decoded to form the transmitted data. The coherent demodulation and detection of BPSK signals derived from a CMC chirp transform processor were experimentally demonstrated and bit error rate (BER) testing was performed. To assess the feasibility of such advanced receiver, the results were compared with the theoretical analysis and plotted for an average BER as a function of signal-to-noise ratio. Another goal of this SBIR program was the development of a commercial product. The commercial product developed was an arbitrary waveform generator. The successful sales have begun with the delivery of the first arbitrary waveform generator.

  9. Microarray analysis of E9.5 reduced folate carrier (RFC1; Slc19a1) knockout embryos reveals altered expression of genes in the cubilin-megalin multiligand endocytic receptor complex

    PubMed Central

    Gelineau-van Waes, Janee; Maddox, Joyce R; Smith, Lynette M; van Waes, Michael; Wilberding, Justin; Eudy, James D; Bauer, Linda K; Finnell, Richard H

    2008-01-01

    Background The reduced folate carrier (RFC1) is an integral membrane protein and facilitative anion exchanger that mediates delivery of 5-methyltetrahydrofolate into mammalian cells. Adequate maternal-fetal transport of folate is necessary for normal embryogenesis. Targeted inactivation of the murine RFC1 gene results in post-implantation embryolethality, but daily folic acid supplementation of pregnant dams prolongs survival of homozygous embryos until mid-gestation. At E10.5 RFC1-/- embryos are developmentally delayed relative to wildtype littermates, have multiple malformations, including neural tube defects, and die due to failure of chorioallantoic fusion. The mesoderm is sparse and disorganized, and there is a marked absence of erythrocytes in yolk sac blood islands. The identification of alterations in gene expression and signaling pathways involved in the observed dysmorphology following inactivation of RFC1-mediated folate transport are the focus of this investigation. Results Affymetrix microarray analysis of the relative gene expression profiles in whole E9.5 RFC1-/- vs. RFC1+/+ embryos identified 200 known genes that were differentially expressed. Major ontology groups included transcription factors (13.04%), and genes involved in transport functions (ion, lipid, carbohydrate) (11.37%). Genes that code for receptors, ligands and interacting proteins in the cubilin-megalin multiligand endocytic receptor complex accounted for 9.36% of the total, followed closely by several genes involved in hematopoiesis (8.03%). The most highly significant gene network identified by Ingenuity™ Pathway analysis included 12 genes in the cubilin-megalin multiligand endocytic receptor complex. Altered expression of these genes was validated by quantitative RT-PCR, and immunohistochemical analysis demonstrated that megalin protein expression disappeared from the visceral yolk sac of RFC1-/- embryos, while cubilin protein was widely misexpressed. Conclusion Inactivation of

  10. Land mobile satellite system requirements

    NASA Technical Reports Server (NTRS)

    Kiesling, J. D.

    1983-01-01

    A Land Mobile Satellite System (LMSS) provides voice, data and related communications services to moving vehicles and persons. Communications between the mobiles and satellite are in the 806-890 MHz band. The satellite translates these signals to a ""fixed services band'' such as 14/12 GHz band (Ku-band), and communicates in this band with fixed terminals called gateways. The gateways are located at convenient places such as telephone switches (which provide entry into the national telephone system), dispatcher headquarters, computer centers, etc. Communications are therefore principally mobile to fixed. A third communications link, also at Ku-band, is needed between the satellite and a single fixed ground station. This link provides satellite command, telemetry and ranging and also provides a network control function. The latter, through a common signalling system, receives requests and assigns channel slots, and otherwise controls, monitors and polices the network and collects billing information.

  11. Land mobile satellite system requirements

    NASA Astrophysics Data System (ADS)

    Kiesling, J. D.

    1983-05-01

    A Land Mobile Satellite System (LMSS) provides voice, data and related communications services to moving vehicles and persons. Communications between the mobiles and satellite are in the 806-890 MHz band. The satellite translates these signals to a ""fixed services band'' such as 14/12 GHz band (Ku-band), and communicates in this band with fixed terminals called gateways. The gateways are located at convenient places such as telephone switches (which provide entry into the national telephone system), dispatcher headquarters, computer centers, etc. Communications are therefore principally mobile to fixed. A third communications link, also at Ku-band, is needed between the satellite and a single fixed ground station. This link provides satellite command, telemetry and ranging and also provides a network control function. The latter, through a common signalling system, receives requests and assigns channel slots, and otherwise controls, monitors and polices the network and collects billing information.

  12. Direct Broadcast Satellite: Radio Program

    NASA Technical Reports Server (NTRS)

    Hollansworth, James E.

    1992-01-01

    NASA is committed to providing technology development that leads to the introduction of new commercial applications for communications satellites. The Direct Broadcast Satellite-Radio (DBS-R) Program is a joint effort between The National Aeronautics and Space Administration (NASA) and The United States Information Agency/Voice of America (USIA/VOA) directed at this objective. The purpose of this program is to define the service and develop the technology for a direct-to-listener satellite sound broadcasting system. The DBS-R Program, as structured by NASA and VOA, is now a three-phase program designed to help the U.S. commercial communications satellite and receiver industry bring about this new communications service. Major efforts are being directed towards frequency planning hardware and service development, service demonstration, and experimentation with new satellite and receiver technology.

  13. Development and operations of nano-satellite FITSAT-1 (NIWAKA)

    NASA Astrophysics Data System (ADS)

    Tanaka, Takushi; Kawamura, Yoshiyuki; Tanaka, Takakazu

    2015-02-01

    FITSAT-1 (NIWAKA) is a 10 cm3 satellite that was deployed from the International Space Station (ISS) on October 5, 2012. It continued to operate until its orbit decayed on July 4, 2013. The main FITSAT-1 mission was to demonstrate a high speed transmitter module developed by our group (115.2 kbps, 5.84 GHz, FSK, 2 W RF output). Each of the JPEG VGA image (640×480 pixels) taken at the time of deployment was received in 2-6 s. The second mission was to make the satellite twinkle as an "artificial star" using high-output LEDs and investigate the possibility of visible light communication between the satellite and the ground. This light from the satellite was photographed in many places. Our FITSAT team succeeded in acquiring the light signal using a photomultiplier attached to a telescope. Moreover, we discovered that the FITSAT-1 rotation speed gradually increased.

  14. The Saturn System's Icy Satellites: New Results from Cassini

    NASA Technical Reports Server (NTRS)

    Lopes-Gautier, Rosaly M.; Buratti, Bonnie; Hendrix, A. R.

    2008-01-01

    Cassini-Huygens is a multidisciplinary, international planetary mission consisting of an orbiting spacecraft and a probe. The Huygens probe successfully landed on Titan's surface on January 14, 2005, while the orbiter has performed observations of Saturn, its rings, satellites, and magnetosphere since it entered orbit around Saturn on July 1, 2004. The Cassini mission has been prolific in its scientific discoveries about the Saturn system. In this special section, we present new mission results with a focus on the 'icy satellites,' which we define as all Saturn's moons with the exception of Titan. The results included in this section have come out of the Cassini SOST--Satellites Orbiter Science Team--a multi-instrument and multidiscipline group that works together to better understand the icy satellites and their interactions with Saturn and its rings. Other papers included in this issue present ground-based observations and interior modeling of these icy moons.

  15. Central Satellite Data Repository Supporting Research and Development

    NASA Astrophysics Data System (ADS)

    Han, W.; Brust, J.

    2015-12-01

    Near real-time satellite data is critical to many research and development activities of atmosphere, land, and ocean processes. Acquiring and managing huge volumes of satellite data without (or with less) latency in an organization is always a challenge in the big data age. An organization level data repository is a practical solution to meeting this challenge. The STAR (Center for Satellite Applications and Research of NOAA) Central Data Repository (SCDR) is a scalable, stable, and reliable repository to acquire, manipulate, and disseminate various types of satellite data in an effective and efficient manner. SCDR collects more than 200 data products, which are commonly used by multiple groups in STAR, from NOAA, GOES, Metop, Suomi NPP, Sentinel, Himawari, and other satellites. The processes of acquisition, recording, retrieval, organization, and dissemination are performed in parallel. Multiple data access interfaces, like FTP, FTPS, HTTP, HTTPS, and RESTful, are supported in the SCDR to obtain satellite data from their providers through high speed internet. The original satellite data in various raster formats can be parsed in the respective adapter to retrieve data information. The data information is ingested to the corresponding partitioned tables in the central database. All files are distributed equally on the Network File System (NFS) disks to balance the disk load. SCDR provides consistent interfaces (including Perl utility, portal, and RESTful Web service) to locate files of interest easily and quickly and access them directly by over 200 compute servers via NFS. SCDR greatly improves collection and integration of near real-time satellite data, addresses satellite data requirements of scientists and researchers, and facilitates their primary research and development activities.

  16. Stereoscopic observations from meteorological satellites

    NASA Astrophysics Data System (ADS)

    Hasler, A. F.; Mack, R.; Negri, A.

    The capability of making stereoscopic observations of clouds from meteorological satellites is a new basic analysis tool with a broad spectrum of applications. Stereoscopic observations from satellites were first made using the early vidicon tube weather satellites (e.g., Ondrejka and Conover [1]). However, the only high quality meteorological stereoscopy from low orbit has been done from Apollo and Skylab, (e.g., Shenk et al. [2] and Black [3], [4]). Stereoscopy from geosynchronous satellites was proposed by Shenk [5] and Bristor and Pichel [6] in 1974 which allowed Minzner et al. [7] to demonstrate the first quantitative cloud height analysis. In 1978 Bryson [8] and desJardins [9] independently developed digital processing techniques to remap stereo images which made possible precision height measurement and spectacular display of stereograms (Hasler et al. [10], and Hasler [11]). In 1980 the Japanese Geosynchronous Satellite (GMS) and the U.S. GOES-West satellite were synchronized to obtain stereo over the central Pacific as described by Fujita and Dodge [12] and in this paper. Recently the authors have remapped images from a Low Earth Orbiter (LEO) to the coordinate system of a Geosynchronous Earth Orbiter (GEO) and obtained stereoscopic cloud height measurements which promise to have quality comparable to previous all GEO stereo. It has also been determined that the north-south imaging scan rate of some GEOs can be slowed or reversed. Therefore the feasibility of obtaining stereoscopic observations world wide from combinations of operational GEO and LEO satellites has been demonstrated. Stereoscopy from satellites has many advantages over infrared techniques for the observation of cloud structure because it depends only on basic geometric relationships. Digital remapping of GEO and LEO satellite images is imperative for precision stereo height measurement and high quality displays because of the curvature of the earth and the large angular separation of the

  17. The exterior tidal potential acting on a satellite. [satellite orbits/satellite perturbation - gravitation effects

    NASA Technical Reports Server (NTRS)

    Musen, P.

    1975-01-01

    A theory is presented that points out the existence of several long period and 'cross effects' in the coefficients in the expansion of the geopotential and in the motion of satellites. The tidal potential, defined as small periodic variations in the geopotential, was calculated. The influence of these geopotential variations on satellite perturbation is examined. Spherical harmonics were employed.

  18. The Galilean Satellites

    NASA Technical Reports Server (NTRS)

    1998-01-01

    In this 'family portrait,' the four Galilean Satellites are shown to scale. These four largest moons of Jupiter shown in increasing distance from Jupiter are (left to right) Io, Europa, Ganymede, and Callisto.

    These global views show the side of volcanically active Io which always faces away from Jupiter, icy Europa, the Jupiter-facing side of Ganymede, and heavily cratered Callisto. The appearances of these neighboring satellites are amazingly different even though they are relatively close to Jupiter (350,000 kilometers for Io; 1, 800,000 kilometers for Callisto). These images were acquired on several orbits at very low 'phase' angles (the sun, spacecraft, moon angle) so that the sun is illuminating the Jovian moons from completely behind the spacecraft, in the same way a full moon is viewed from Earth. The colors have been enhanced to bring out subtle color variations of surface features. North is to the top of all the images which were taken by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft.

    Io, which is slightly larger than Earth's moon, is the most colorful of the Galilean satellites. Its surface is covered by deposits from actively erupting volcanoes, hundreds of lava flows, and volcanic vents which are visible as small dark spots. Several of these volcanoes are very hot; at least one reached a temperature of 2000 degrees Celsius (3600 degrees Fahrenheit) in the summer of 1997. Prometheus, a volcano located slightly right of center on Io's image, was active during the Voyager flybys in 1979 and is still active as Galileo images were obtained. This global view was obtained in September 1996 when Galileo was 485,000 kilometers from Io; the finest details that can be discerned are about 10 km across. The bright, yellowish and white materials located at equatorial latitudes are believed to be composed of sulfur and sulfur dioxide. The polar caps are darker and covered by a redder material.

    Europa has a very different surface from its

  19. The Galilean Satellites

    NASA Technical Reports Server (NTRS)

    1998-01-01

    In this 'family portrait,' the four Galilean Satellites are shown to scale. These four largest moons of Jupiter shown in increasing distance from Jupiter are (left to right) Io, Europa, Ganymede, and Callisto.

    These global views show the side of volcanically active Io which always faces away from Jupiter, icy Europa, the Jupiter-facing side of Ganymede, and heavily cratered Callisto. The appearances of these neighboring satellites are amazingly different even though they are relatively close to Jupiter (350,000 kilometers for Io; 1, 800,000 kilometers for Callisto). These images were acquired on several orbits at very low 'phase' angles (the sun, spacecraft, moon angle) so that the sun is illuminating the Jovian moons from completely behind the spacecraft, in the same way a full moon is viewed from Earth. The colors have been enhanced to bring out subtle color variations of surface features. North is to the top of all the images which were taken by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft.

    Io, which is slightly larger than Earth's moon, is the most colorful of the Galilean satellites. Its surface is covered by deposits from actively erupting volcanoes, hundreds of lava flows, and volcanic vents which are visible as small dark spots. Several of these volcanoes are very hot; at least one reached a temperature of 2000 degrees Celsius (3600 degrees Fahrenheit) in the summer of 1997. Prometheus, a volcano located slightly right of center on Io's image, was active during the Voyager flybys in 1979 and is still active as Galileo images were obtained. This global view was obtained in September 1996 when Galileo was 485,000 kilometers from Io; the finest details that can be discerned are about 10 km across. The bright, yellowish and white materials located at equatorial latitudes are believed to be composed of sulfur and sulfur dioxide. The polar caps are darker and covered by a redder material.

    Europa has a very different surface from its

  20. Factors affecting frequency and orbit utilization by high power transmission satellite systems

    NASA Technical Reports Server (NTRS)

    Kuhns, P. W.; Miller, E. F.; Malley, T. A.

    1972-01-01

    The factors affecting the sharing of the geostationary orbit by high power (primarily television) satellite systems having the same or adjacent coverage areas and by satellites occupying the same orbit segment are examined and examples using the results of computer computations are given. The factors considered include: required protection ratio, receiver antenna patterns, relative transmitter power, transmitter antenna patterns, satellite grouping, and coverage pattern overlap. The results presented indicated the limits of system characteristics and orbit deployment which can result from mixing systems.

  1. The C-terminal segment of the 1,3-beta-glucanase Ole e 9 from olive (Olea europaea) pollen is an independent domain with allergenic activity: expression in Pichia pastoris and characterization.

    PubMed Central

    Palomares, Oscar; Villalba, Mayte; Rodríguez, Rosalía

    2003-01-01

    Several allergenic proteins, such as the 1,3-beta-glucanases, have been associated with plant defence responses. Ole e 9 (46 kDa) is a 1,3-beta-glucanase and major allergen from olive pollen, which is a principal cause of allergy in Mediterranean countries. Its C-terminal segment (101 amino acid residues) has been produced as a recombinant polypeptide in the yeast Pichia pastoris. The cDNA encoding the polypeptide was inserted into the plasmid vector pPICZalpha-A and overexpressed in KM71 yeast cells. The recombinant product was purified by size-exclusion chromatography followed by reversed-phase HPLC. Edman degradation, MS and CD were used to determine molecular properties of the recombinant polypeptide, which exhibited 16% alpha-helix and 30% beta-sheet as regular elements of secondary structure. Disulphide bridges of the molecule were determined at positions Cys-14-Cys-76, Cys-33-Cys-94 and Cys-39-Cys-48. The high IgE-binding capability of the recombinant C-terminal segment of Ole e 9 against sera from Ole e 9-sensitive individuals, which was determined by immunoblotting and ELISA inhibition, supported the proper folding of the polypeptide and the maintenance of antigenic properties that it exhibits as a part of the whole allergen. These data indicated that this portion of Ole e 9 constitutes an independent domain, which could be used to study its three-dimensional structure and function, as well as for clinical purposes such as diagnosis and specific immunotherapy. Since it shows sequence similarity with portions of 1,3-beta-glucanases from plant tissues and the Gas/Phr/Epd protein families involved in yeast morphogenesis, we suggest that this domain could play an equivalent functional role within these enzymes. PMID:12392450

  2. The NOAA Satellite Observing System Architecture Study

    NASA Technical Reports Server (NTRS)

    Volz, Stephen; Maier, Mark; Di Pietro, David

    2016-01-01

    NOAA is beginning a study, the NOAA Satellite Observing System Architecture (NSOSA) study, to plan for the future operational environmental satellite system that will follow GOES and JPSS, beginning about 2030. This is an opportunity to design a modern architecture with no pre-conceived notions regarding instruments, platforms, orbits, etc. The NSOSA study will develop and evaluate architecture alternatives to include partner and commercial alternatives that are likely to become available. The objectives will include both functional needs and strategic characteristics (e.g., flexibility, responsiveness, sustainability). Part of this study is the Space Platform Requirements Working Group (SPRWG), which is being commissioned by NESDIS. The SPRWG is charged to assess new or existing user needs and to provide relative priorities for observational needs in the context of the future architecture. SPRWG results will serve as input to the process for new foundational (Level 0 and Level 1) requirements for the next generation of NOAA satellites that follow the GOES-R, JPSS, DSCOVR, Jason-3, and COSMIC-2 missions.

  3. Multi-mission Satellite Management

    NASA Astrophysics Data System (ADS)

    Jamilkowski, M. L.; Teter, M. A.; Grant, K. D.; Dougherty, B.; Cochran, S.

    2015-12-01

    NOAA's next-generation environmental satellite, the Joint Polar Satellite System (JPSS) replaces the current Polar-orbiting Operational Environmental Satellites (POES). JPSS satellites carry sensors which collect meteorological, oceanographic, climatological, and solar-geophysical observations of the earth, atmosphere, and space. The first JPSS satellite was launched in 2011 and is currently NOAA's primary operational polar satellite. The JPSS ground system is the Common Ground System (CGS), and provides command, control, and communications (C3) and data processing (DP). A multi-mission system, CGS provides combinations of C3/DP for numerous NASA, NOAA, DoD, and international missions. In preparation for the next JPSS satellite, CGS improved its multi-mission capabilities to enhance mission operations for larger constellations of earth observing satellites with the added benefit of streamlining mission operations for other NOAA missions. CGS's multi-mission capabilities allows management all of assets as a single enterprise, more efficiently using ground resources and personnel and consolidating multiple ground systems into one. Sophisticated scheduling algorithms compare mission priorities and constraints across all ground stations, creating an enterprise schedule optimized to mission needs, which CGS executes to acquire the satellite link, uplink commands, downlink and route data to the operations and data processing facilities, and generate the final products for delivery to downstream users. This paper will illustrate the CGS's ability to manage multiple, enterprise-wide polar orbiting missions by demonstrating resource modeling and tasking, production of enterprise contact schedules for NOAA's Fairbanks ground station (using both standing and ad hoc requests), deconflicting resources due to ground outages, and updating resource allocations through dynamic priority definitions.

  4. Security Concepts for Satellite Links

    NASA Astrophysics Data System (ADS)

    Tobehn, C.; Penné, B.; Rathje, R.; Weigl, A.; Gorecki, Ch.; Michalik, H.

    2008-08-01

    The high costs to develop, launch and maintain a satellite network makes protecting the assets imperative. Attacks may be passive such as eavesdropping on the payload data. More serious threat are active attacks that try to gain control of the satellite, which may lead to the total lost of the satellite asset. To counter these threats, new satellite and ground systems are using cryptographic technologies to provide a range of services: confidentiality, entity & message authentication, and data integrity. Additionally, key management cryptographic services are required to support these services. This paper describes the key points of current satellite control and operations, that are authentication of the access to the satellite TMTC link and encryption of security relevant TM/TC data. For payload data management the key points are multi-user ground station access and high data rates both requiring frequent updates and uploads of keys with the corresponding key management methods. For secure satellite management authentication & key negotiation algorithms as HMAC-RIPEMD160, EC- DSA and EC-DH are used. Encryption of data uses algorithms as IDEA, AES, Triple-DES, or other. A channel coding and encryption unit for payload data provides download data rates up to Nx250 Mbps. The presented concepts are based on our experience and heritage of the security systems for all German MOD satellite projects (SATCOMBw2, SAR-Lupe multi- satellite system and German-French SAR-Lupe-Helios- II systems inter-operability) as well as for further international (KOMPSAT-II Payload data link system) and ESA activities (TMTC security and GMES).

  5. Group X

    SciTech Connect

    Fields, Susannah

    2007-08-16

    This project is currently under contract for research through the Department of Homeland Security until 2011. The group I was responsible for studying has to remain confidential so as not to affect the current project. All dates, reference links and authors, and other distinguishing characteristics of the original group have been removed from this report. All references to the name of this group or the individual splinter groups has been changed to 'Group X'. I have been collecting texts from a variety of sources intended for the use of recruiting and radicalizing members for Group X splinter groups for the purpose of researching the motivation and intent of leaders of those groups and their influence over the likelihood of group radicalization. This work included visiting many Group X websites to find information on splinter group leaders and finding their statements to new and old members. This proved difficult because the splinter groups of Group X are united in beliefs, but differ in public opinion. They are eager to tear each other down, prove their superiority, and yet remain anonymous. After a few weeks of intense searching, a list of eight recruiting texts and eight radicalizing texts from a variety of Group X leaders were compiled.

  6. Advanced Communications Technology Satellite (ACTS)

    NASA Technical Reports Server (NTRS)

    Gedney, Richard T.; Schertler, Ronald J.

    1989-01-01

    The NASA Advanced Communications Technology Satellite (ACTS) was conceived to help maintain U.S. leadership in the world's communications-satellite market. This experimental satellite is expected to be launched by NASA in 1992 and to furnish the technology necessary for establishing very small aperture terminal digital networks which provide on-demand full-mesh connectivity, and 1.544-MBPS services with only a single hop. Utilizing on-board switching and processing, each individual voice or data circuit can be separately routed to any location in the network. This paper provides an overview of the ACTS and discusses the value of the technology for future communications systems.

  7. Use of communications. [satellite communication

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Progress in the field of satellite communications is reviewed, and useful services which may be provided by future satellite communications systems are considered. Recommendations are made with regard to mobile communications for use on land and at sea, position determination, mineral and energy exploration, the possibility of using electronic means to assist in main delivery, education and health-care experiments, and the use of satellite telecommunications to enhance the quality of life in rural areas by making available a full range of educational and entertainment programs. The needs of the amateur radio community are also considered.

  8. Progress in satellite tracking cranes

    USGS Publications Warehouse

    Ellis, D.H.; Smith, D.G.; Olsen, G.H.; Fuller, M.R.; Landfried, S.E.; Higuchi, H.; Vermillion, C.H.

    1992-01-01

    We review the history of tracking cranes with satellite telemetry and identify some of the difficulties in designing satellite transmitters and harnesses for cranes. Miniaturization of these transmitters and a plethora of harnessing experiments since 1989 allow us to recommend limited application of this technology to all species of cranes. We are still uncertain, however, if cranes harnessed with satellite telemetry devices are able to reproduce after migration. Because of this uncertainty, we urge caution in the use of this technology, especially with breeding adults in severely endangered populations. This manuscript also describes continuing research needs.

  9. Geometry of a mapping satellite.

    USGS Publications Warehouse

    Snyder, J.P.

    1982-01-01

    The proposed mapping satellite Mapsat is to consist of fixed fore, vertical, and aft linear detector arrays, any two of which may be used simultaneously to obtain digital images for one- dimensional stereo correlation. The satellite attitude may be varied according to Fourier series to enable a given detector on one array to follow closely the groundtrack sensed by the corresponding detector on another array throughout the orbit. These tracking errors are negligible for a satellite stable within anticipated ranges. The required computations have been programmed in FORTRAN IV. -Author

  10. Satellite TV in the UK

    NASA Astrophysics Data System (ADS)

    Stanyard, Roger

    1991-11-01

    The development of DBS TV is considered in terms of the type of supporting satellite to be selected with attention given to the medium-power concept FSS satellites. Predictions are made regarding the combination direct-to-home/DBS satellite-broadcasting industry emphasizing the use of DBS TV for program delivery and not as a substitute for cable and other distribution methods. DBS TV is an effective technology for reaching audience segments that cannot be included by conventional terrestrial and cable means.

  11. The economics of satellite retrieval

    NASA Technical Reports Server (NTRS)

    Price, Kent M.; Greenberg, Joel S.

    1988-01-01

    The economics of space operations with and without the Space Station have been studied in terms of the financial performance of a typical communications-satellite business venture. A stochastic Monte-Carlo communications-satellite business model is employed which includes factors such as satellite configuration, random and wearout failures, reliability of launch and space operations, stand-down time resulting from failures, and insurance by operation. Financial performance impacts have been evaluated in terms of the magnitude of investment, net present value, and return on investment.

  12. The french educational satellite arsene

    NASA Astrophysics Data System (ADS)

    Danvel, M.; Escudier, B.

    ARSENE (Ariane, Radio-amateur, Satellite pour l'ENseignement de l'Espace) is a telecommunications satellite for Amateur Space Service. Its main feature is that more than 100 students from French engineering schools and universities have been working since 1979 for definition phase and satellite development. The highest IAF awards has been obtained by "ARSENE students" in Tokyo (1980) and Rome (1981). The French space agency, CNES and French aerospace industries are supporting the program. The European Space Agency offered to place ARSENE in orbit on the first Ariane mark IV launch late 1985.

  13. Group Flow and Group Genius

    ERIC Educational Resources Information Center

    Sawyer, Keith

    2015-01-01

    Keith Sawyer views the spontaneous collaboration of group creativity and improvisation actions as "group flow," which organizations can use to function at optimum levels. Sawyer establishes ideal conditions for group flow: group goals, close listening, complete concentration, being in control, blending egos, equal participation, knowing…

  14. A global satellite-assisted precipitation climatology

    NASA Astrophysics Data System (ADS)

    Funk, C.; Verdin, A.; Michaelsen, J.; Peterson, P.; Pedreros, D.; Husak, G.

    2015-10-01

    Accurate representations of mean climate conditions, especially in areas of complex terrain, are an important part of environmental monitoring systems. As high-resolution satellite monitoring information accumulates with the passage of time, it can be increasingly useful in efforts to better characterize the earth's mean climatology. Current state-of-the-science products rely on complex and sometimes unreliable relationships between elevation and station-based precipitation records, which can result in poor performance in food and water insecure regions with sparse observation networks. These vulnerable areas (like Ethiopia, Afghanistan, or Haiti) are often the critical regions for humanitarian drought monitoring. Here, we show that long period of record geo-synchronous and polar-orbiting satellite observations provide a unique new resource for producing high-resolution (0.05°) global precipitation climatologies that perform reasonably well in data-sparse regions. Traditionally, global climatologies have been produced by combining station observations and physiographic predictors like latitude, longitude, elevation, and slope. While such approaches can work well, especially in areas with reasonably dense observation networks, the fundamental relationship between physiographic variables and the target climate variables can often be indirect and spatially complex. Infrared and microwave satellite observations, on the other hand, directly monitor the earth's energy emissions. These emissions often correspond physically with the location and intensity of precipitation. We show that these relationships provide a good basis for building global climatologies. We also introduce a new geospatial modeling approach based on moving window regressions and inverse distance weighting interpolation. This approach combines satellite fields, gridded physiographic indicators, and in situ climate normals. The resulting global 0.05° monthly precipitation climatology, the Climate

  15. A global satellite assisted precipitation climatology

    USGS Publications Warehouse

    Funk, Christopher C.; Verdin, Andrew P.; Michaelsen, Joel C.; Pedreros, Diego; Husak, Gregory J.; Peterson, P.

    2015-01-01

    Accurate representations of mean climate conditions, especially in areas of complex terrain, are an important part of environmental monitoring systems. As high-resolution satellite monitoring information accumulates with the passage of time, it can be increasingly useful in efforts to better characterize the earth's mean climatology. Current state-of-the-science products rely on complex and sometimes unreliable relationships between elevation and station-based precipitation records, which can result in poor performance in food and water insecure regions with sparse observation networks. These vulnerable areas (like Ethiopia, Afghanistan, or Haiti) are often the critical regions for humanitarian drought monitoring. Here, we show that long period of record geo-synchronous and polar-orbiting satellite observations provide a unique new resource for producing high resolution (0.05°) global precipitation climatologies that perform reasonably well in data sparse regions. Traditionally, global climatologies have been produced by combining station observations and physiographic predictors like latitude, longitude, elevation, and slope. While such approaches can work well, especially in areas with reasonably dense observation networks, the fundamental relationship between physiographic variables and the target climate variables can often be indirect and spatially complex. Infrared and microwave satellite observations, on the other hand, directly monitor the earth's energy emissions. These emissions often correspond physically with the location and intensity of precipitation. We show that these relationships provide a good basis for building global climatologies. We also introduce a new geospatial modeling approach based on moving window regressions and inverse distance weighting interpolation. This approach combines satellite fields, gridded physiographic indicators, and in situ climate normals. The resulting global 0.05° monthly precipitation climatology, the Climate

  16. Planetary satellites - an update

    NASA Astrophysics Data System (ADS)

    Beatty, J. K.

    1983-11-01

    General features of all known planetary satellites in the system are provided, and attention is focused on prominent features of several of the bodies. Titan has an atmosphere 1.5 times earth's at sea level, a well a a large body of liquid which may be ethane, CH4, and disolved N2. Uranus has at least five moons, whose masses have recently been recalculated and determined to be consistent with predictions of outer solar system composition. Io's violent volcanic activity is a demonstration of the conversion of total energy (from Jupiter) to heat, i.e., interior melting and consequent volcanoes. Plumes of SO2 have been seen and feature temperatures of up to 650 K. Enceladus has a craterless, cracked surface, indicating the presence of interior ice and occasional breakthroughs from tidal heating. Hyperion has a chaotic rotation, and Iapetus has one light and one dark side, possibly from periodic collisions with debris clouds blasted off the surface of the outer moon Phoebe.

  17. Hubble Space Telescope satellite

    NASA Technical Reports Server (NTRS)

    Mitchell, R. E.

    1985-01-01

    The Hubble Space Telescope, named for the American astronomer Edwin Powell Hubble, will be the largest and most powerful astronomical instrument ever orbited. Placed above the obscuring effects of the earth's atmosphere in a 600-km orbit, this remotely-controlled, free-flying satellite observatory will expand the terrestrial-equivalent resolution of the universe by a factor of seven, or a volumetric factor of 350. This telescope has a 2.4-m primary mirror and can accommodate five scientific instruments (cameras, spectrographs and photometers). The optics are suitable for a spectral range from 1100 angstrom to 1 mm wavelength. With a projected service life of fifteen years, the spacecraft can be serviced on-orbit for replacement of degraded systems, to insert advanced scientific instruments, and to reboost the telescope from decayed altitudes. The anticipated image quality will be a result of extremely precise lambda/20 optics, stringent cleanliness, and very stable pointing: jitter will be held to less than 0.01 arcsecond for indefinite observation periods, consistent with instrument apertures as small as 0.1 arcsecond.

  18. Satellite Propellant Pump Research

    NASA Technical Reports Server (NTRS)

    Schneider, Steven J.; Veres, Joseph P.; Hah, Chunill; Nerone, Anthony L.; Cunningham, Cameron C.; Kraft, Thomas G.; Tavernelli, Paul F.; Fraser, Bryan

    2005-01-01

    NASA Glenn initiated a satellite propellant pump technology demonstration program. The goal was to demonstrate the technologies for a 60 percent efficient pump at 1 gpm flow rate and 500 psia pressure rise. The pump design and analysis used the in-house developed computer codes named PUMPA and HPUMP3D. The requirements lead to a 4-stage impeller type pump design with a tip diameter of 0.54 inches and a rotational speed of 57,000 rpm. Analyses indicated that flow cavitation was not a problem in the design. Since the flow was incompressible, the stages were identical. Only the 2-stage pump was designed, fabricated, assembled, and tested for demonstration. Water was selected as the surrogate fluid for hydrazine in this program. Complete mechanical design including stress and dynamic analyses were conducted. The pump was driven by an electric motor directly coupled to the impellers. Runs up to 57,000 rpm were conducted, where a pressure rise of 200 psia at a flow rate of 0.8 gpm was measured to validate the design effort.

  19. Isopermutation group

    SciTech Connect

    Muktibodh, A. S.

    2015-03-10

    The concept of ‘Isotopy’ as formulated by Ruggero Maria Santilli [1, 2, 3] plays a vital role in the development of Iso mathematics. Santilli defined iso-fields of characteristic zero. In this paper we extend this definition to define Iso-Galois fields [4] which are essentially of non-zero characteristic. Isotopically isomorphic realizations of a group define isopermutation group which gives a clear cut distinction between automorphic groups and isotopic groups.

  20. Analysis of cloud characteristics derived from archived satellite data

    NASA Technical Reports Server (NTRS)

    Hughes, N. A.; Henderson-Sellers, A.

    1983-01-01

    The present investigation is concerned with the differing scientific user community requirements for cloud data and the nature of archived satellite data. It is concluded that information on cloud characteristics and cloud cover is of the utmost importance for at least three scientific research areas, viz. numerical weather forecasting, environmental remote sensing, and climatic monitoring and modelling. However, these three user groups require information at different levels of temporal and spatial resolution, and the nature of the comparison between surface and satellite assessment of cloud cover differs among the three groups. Taking into account the diverse requirements of the scientific community and difficulty of a mutually agreed definition of the cloud parameters, a number of recommendations are made. It is suggested that radiance data, not cloud data, should be archived directly from satellite observations, and that the highest spatial and temporal resolutions available should be retained in the archive.

  1. Effects of satellite transmitters on captive and wild mallards

    USGS Publications Warehouse

    Kesler, Dylan C.; Raedeke, Andrew H.; Foggia, Jennifer R.; Beatty, William S.; Webb, Elisabeth B.; Humburg, Dale D.; Naylor, Luke W.

    2014-01-01

    Satellite telemetry has become a leading method for studying large-scale movements and survival in birds, yet few have addressed potential effects of the larger and heavier tracking equipment on study subjects. We simultaneously evaluated effects of satellite telemetry equipment on captive and wild mallards (Anas platyrhynchos) to assess impacts on behavior, body mass, and movement. We randomly assigned 55 captive ducks to one of 3 treatment groups, including a standard body harness group, a modified harness group, and a control group. Ducks in the control group were not fitted with equipment, whereas individuals in the other 2 groups were fitted with dummy transmitters attached with a Teflon ribbon harness or with a similar harness constructed of nylon cord. At the conclusion of the 14-week captive study, mean body mass of birds in the control group was 40–105 g (95% CI) greater than birds with standard harnesses, and 28–99 g (95% CI) greater than birds with modified harnesses. Further, results of focal behavior observations indicated ducks with transmitters were less likely to be in water than control birds. We also tested whether movements of wild birds marked with a similar Teflon harness satellite transmitter aligned with population movements reported by on-the-ground observers who indexed local abundances of mid-continent mallards throughout the non-breeding period. Results indicated birds marked with satellite transmitters moved concurrently with the larger unmarked population. Our results have broad implications for field research and suggest that investigators should consider potential for physiological and behavioral effects brought about by tracking equipment. Nonetheless, results from wild ducks indicate satellite telemetry has the potential to provide useful movement data.

  2. Hot Groups.

    ERIC Educational Resources Information Center

    Vail, Kathleen

    1996-01-01

    Collaborators sparked by creative ideas and obsessed by a common task may not realize they're part of a "hot group"--a term coined by business professors Harold J. Leavitt and Jean Lipman-Blumen. Spawned by group decision making and employee empowerment, hot groups can flourish in education settings. They're typically small, short lived, and goal…

  3. NASA's TRMM Satellite Captures Cosme

    NASA Video Gallery

    On Tuesday, June 25, Cosme became a hurricane. NASA's TRMM satellite flew over Cosme at 9:46 a.m. EDT shortly before it was upgraded to a hurricane. A rainfall analysis from TRMM's Microwave Imager...

  4. Satellite Movie Shows Erika Dissipate

    NASA Video Gallery

    This animation of visible and infrared imagery from NOAA's GOES-West satellite from Aug. 27 to 29 shows Tropical Storm Erika move through the Eastern Caribbean Sea and dissipate near eastern Cuba. ...

  5. Satellite Technology for Education Distribution

    ERIC Educational Resources Information Center

    Campbell, Jack M.

    1974-01-01

    The use of satellite technology to bring much needed information, such as career education messages to remote areas of Rocky Mountain States is the subject of this paper. Both software and hardware aspects of this demonstration project are discussed. (Author)

  6. TRMM Satellite Video of Amara

    NASA Video Gallery

    TRMM satellite on Dec. 16, at 2043 UTC showed scattered bands of moderate to heavy rain falling at a rate of over 76.9 mm/3 inches per hour spiraling into Amara's center. Cloud tops reached 13km/~8...

  7. Small satellite radiometric measurement system

    SciTech Connect

    Weber, P.G.

    1992-01-01

    A critical need for the US Global Change Research Program is to provide continuous, well-calibrated radiometric data for the earth`s radiation budget. This paper describes a new, compact, relatively light-weight, adaptable radiometer which will provide both spectrally integrated measurements and data in selected spectral bands. The radiometer design is suitable for use on small satellites, aircraft, or remotely piloted aircraft (RPAs). An example of the implementation of this radiometer on a small satellite is given. Significant benefits derive from simultaneous measurements of specific narrow (in wavelength) spectral features; such data may be obtained by combining LARI with a compact spectrometer on the same platform. Well-chosen satellite orbits allow one to use data from other satellites (e.g. DMSP) to enhance the data product, or to provide superior coverage of specific locations. 23 refs.

  8. Earth Resources Technology Satellite (ERTS)

    NASA Technical Reports Server (NTRS)

    1971-01-01

    The Earth Resources Technology Satellite (ERTS) mock-up in a space chamber test at General Electric's Space Division. The ERTS program represented a concentrated effort to observe and monitor the limited resources of the Earth, in order to best conserve and utilize the resources in support of a burgeoning world population. The first ERTS was launched in 1972 and was later named Land Remote-Sensing Satellite (Landsat), to better represent the civil satellite program's prime emphasis on remote sensing of land resources. Multiple sensors survey and relay back masses of data in various ways from the Landsat. NASA has built 7 Land Remote Sensing Satellites, which have helped agricultural experts pick up underutilized land areas and new prospects for land use through irrigation. It has also assisted in pinpointing the spread of crop disease and in charting new uses of the sea for oceanographers.

  9. Satellite tracking of threatened species

    USGS Publications Warehouse

    Williams, M.; Lunsford, A.; Ellis, D.; Robinson, J.; Coronado, P.; Campbell, W.

    1998-01-01

    In 1990, a joint effort of two U.S. federal agencies, NASA Goddard Space Flight Center (GSFC) and the Patuxent Wildlife Research Center, began. We initially joined forces in a project that used satellite telemetry to discover the winter home of a tiny dwindling population of Siberian Cranes. Since then several projects have emerged, and a web site was created to follow some of these activities. This web site is called the Satellite Tracking of Threatened Species and its location is http://sdcd.gsfc.nasa.gov/ISTO/satellite_tracking. It describes the overall program, and links you to three subsections that describe the projects in more detail: Satellite Direct Readout, Birdtracks, and Birdworld.

  10. Satellite stratospheric aerosol measurement validation

    NASA Technical Reports Server (NTRS)

    Russell, P. B.; Mccormick, M. P.

    1984-01-01

    The validity of the stratospheric aerosol measurements made by the satellite sensors SAM II and SAGE was tested by comparing their results with each other and with results obtained by other techniques (lider, dustsonde, filter, and impactor). The latter type of comparison required the development of special techniques that convert the quantity measured by the correlative sensor (e.g., particle backscatter, number, or mass) to that measured by the satellite sensor (extinction) and quantitatively estimate the uncertainty in the conversion process. The results of both types of comparisons show agreement within the measurement and conversion uncertainties. Moreover, the satellite uncertainty is small compared to aerosol natural variability (caused by seasonal changes, volcanoes, sudden warmings, and vortex structure). It was concluded that the satellite measurements are valid.

  11. Satellite stratospheric aerosol measurement validation

    NASA Technical Reports Server (NTRS)

    Russell, P. B.; Mccormick, M. P.

    1984-01-01

    The validity of the stratospheric aerosol measurements made by the satellite sensors SAM II and SAGE was tested by comparing their results with each other and with results obtained by other techniques (lider, dustsonde, filter, and impactor). The latter type of comparison required the development of special techniques that convert the quantity measured by the correlative sensor (e.g. particle backscatter, number, or mass) to that measured by the satellite sensor (extinction) and quantitatively estimate the uncertainty in the conversion process. The results of both types of comparisons show agreement within the measurement and conversion uncertainties. Moreover, the satellite uncertainty is small compared to aerosol natural variability (caused by seasonal changes, volcanoes, sudden warmings, and vortex structure). It was concluded that the satellite measurements are valid.

  12. Cloudsat Satellite Images of Amanda

    NASA Video Gallery

    NASA's CloudSat satellite flew over Hurricane Amanda on May 25, at 5 p.m. EDT and saw a deep area of moderate to heavy-moderate precipitation below the freezing level (where precipitation changes f...

  13. A Satellite Interference Location System

    NASA Astrophysics Data System (ADS)

    Smith, William Whitfield, Jr.

    1990-01-01

    This dissertation describes the design and development of a system for inferring the position of terrestrial satellite uplink stations using existing domestic satellites with minimal disruption to normal satellite operation. Two methods are presented by which a quantity measured at a terrestrial receiving site is mapped into a curve of possible uplink locations on the Earth's surface. One method involves measuring differential time delays of a single uplink signal observed through two adjacent spacecraft. Another method uses a short baseline interferometer composed of the two cross-polarized and spatially separated antenna feeds aboard an affected satellite. A unique location or two dimensional solution is obtained by employing an appropriate combination of the two presented methods. A system for measurement of the required differential delays and phases is described in addition to the experimental work performed to demonstrate the feasibility of these location methods.

  14. Reduced domestic satellite orbit spacing

    NASA Astrophysics Data System (ADS)

    Sharp, G. L.

    The demand for services provided by communications satellites in geostationary orbit is growing, and problems arise with respect to the required increase in capacity. One approach for providing such an increase involves the employment of more satellites operating at smaller orbital spacings. The present investigation is concerned with the results of technical studies conducted by the Federal Communications Commission (FCC) to determine the feasibility of reducing orbital spacings between U.S. 'domestic fixed satellites' (domsats). Attention is given to details regarding the usable orbital arc, an adjacent satellite interference model, antenna sidelobe patterns, a single entry analysis, a 4/6 GHz aggregate analysis, results for the 4/6 GHz bands, results for the 12/14 GHz bands, data services, voice services, video reception, and high power spot beams.

  15. Visual Data Analysis for Satellites

    NASA Technical Reports Server (NTRS)

    Lau, Yee; Bhate, Sachin; Fitzpatrick, Patrick

    2008-01-01

    The Visual Data Analysis Package is a collection of programs and scripts that facilitate visual analysis of data available from NASA and NOAA satellites, as well as dropsonde, buoy, and conventional in-situ observations. The package features utilities for data extraction, data quality control, statistical analysis, and data visualization. The Hierarchical Data Format (HDF) satellite data extraction routines from NASA's Jet Propulsion Laboratory were customized for specific spatial coverage and file input/output. Statistical analysis includes the calculation of the relative error, the absolute error, and the root mean square error. Other capabilities include curve fitting through the data points to fill in missing data points between satellite passes or where clouds obscure satellite data. For data visualization, the software provides customizable Generic Mapping Tool (GMT) scripts to generate difference maps, scatter plots, line plots, vector plots, histograms, timeseries, and color fill images.

  16. Taos: A low cost satellite

    NASA Astrophysics Data System (ADS)

    Jung, P.

    Aerospatiale, under contract to CNES, has studied a new satellite based system with the double mission of mobile tracking and paging. This is called Taos. A constellation of five Taos satellites will allow positioning with an accuracy of 1 km, as well as small message transmission with a maximum time delay of 2 hours. Using a low earth orbit, Taos will have a small power budget, with the attendant gains in dimensions, mass, and eventually cost. The emergence of such class of lightsats has been fostered by the progress of electronics, as well as the new small launchers now being offered. Furthermore, the market is clearly hungry for ever more worldwide data collection. This paper describes the Taos system of satellite and ground segment, for which a primary goal will be a significant reduction of the recurring price. Weighing 152 kg, each satellite will have a power of 270 W.

  17. Satellite Imagery Via Personal Computer

    NASA Technical Reports Server (NTRS)

    1989-01-01

    Automatic Picture Transmission (APT) was incorporated by NASA in the Tiros 8 weather satellite. APT included an advanced satellite camera that immediately transmitted a picture as well as low cost receiving equipment. When an advanced scanning radiometer was later introduced, ground station display equipment would not readily adjust to the new format until GSFC developed an APT Digital Scan Converter that made them compatible. A NASA Technical Note by Goddard's Vermillion and Kamoski described how to build a converter. In 1979, Electro-Services, using this technology, built the first microcomputer weather imaging system in the U.S. The company changed its name to Satellite Data Systems, Inc. and now manufactures the WeatherFax facsimile display graphics system which converts a personal computer into a weather satellite image acquisition and display workstation. Hardware, antennas, receivers, etc. are also offered. Customers include U.S. Weather Service, schools, military, etc.

  18. Commercial satellite broadcasting for Europe

    NASA Astrophysics Data System (ADS)

    Forrest, J. R.

    1988-12-01

    A review is presented of the current television broadcasting situation in European countries, which involves a varied mix of terrestrial VHF or UHF systems and cable networks. A small market has emerged in Europe for receivers using the low-power telecommunications satellite transmission between the program providers and cable network companies. This is expected to change with the launch of medium-power pan-European telecommunication satellites (e.g. ASTRA, EUTELSAT II), which are now directly addressing the market of home reception. DBS (direct broadcast satellite) in the UK, using the D-MAC transmission standard, will offer three additional television channels, data broadcasting services, and a planned evolution to compatible forms of wide-screen, high-definition television. Comments are given on receiver and conditional access system standardization. Some views are expressed on satellite broadcasting as part of an overall broadcasting framework for the future.

  19. Satellite Teleconferencing in the Caribbean.

    ERIC Educational Resources Information Center

    Sankar, Hollis C.

    1985-01-01

    Discusses the need for, and the development, use, and future trends of, the University of the West Indies Distance Teaching Experiment, which utilizes telephone and communications satellite technology teleconferencing to extend educational opportunities to the peoples of the Caribbean. (MBR)

  20. Satellite observation of effusive volcanism

    USGS Publications Warehouse

    Williams, R.S.; Friedman, J.D.

    1970-01-01

    Infrared emission from an active effusive volcanic eruption on Surtsey, Vestmannaeyjar, Iceland, was recorded by airborne and satellite infrared systems at irregular intervals between 19 August and 3 October 1966. Ground and lava temperature measurements and volumetric lava outflow data permitted a comparison to be made between total thermal-energy yield and radiant emission recorded by the satellite system. The Nimbus HRIR recorded radiant emission at a level of about 3% of the estimated total thermal yield.

  1. Legal aspects of satellite teleconferencing

    NASA Technical Reports Server (NTRS)

    Smith, D. D.

    1971-01-01

    The application of satellite communications for teleconferencing purposes is discussed. The legal framework within which such a system or series of systems could be developed is considered. The analysis is based on: (1) satellite teleconferencing regulation, (2) the options available for such a system, (3) regulatory alternatives, and (4) ownership and management aspects. The system is designed to provide a capability for professional education, remote medical diagnosis, business conferences, and computer techniques.

  2. Intelsat satellite scheduled for launch

    NASA Technical Reports Server (NTRS)

    1981-01-01

    The launch schedule for Intelsat 5-B, the prime Intelsat satellite to provide communications services between the Americas, Europe, the Middle East, and Africa, is presented. The planned placement of the satellite into an elliptical transfer orbit, and circularization of the orbit at geosynchronous altitude over the equator are described. Characteristics of the Atlas Centaur launch vehicle, AC-56, are given. The launch operation is summarized and the launch sequence presented. The Intelsat team and contractors are listed.

  3. The data distribution satellite system

    NASA Technical Reports Server (NTRS)

    Bruno, Ronald C.; Weinberg, Aaron

    1991-01-01

    The Data Distributed Satellite (DDS) will be capable of providing the space research community with inexpensive and easy access to space payloads and space data. Furthermore, the DDS is shown to be a natural outgrowth of advances and evolution in both NASA's Space Network and commercial satellite communications. The roadmap and timescale for this evolution is described along with key demonstrations, proof-of-concept models, and required technology development that will support the projected system evolution toward the DDS.

  4. Satellite lifetime routine user's manual

    NASA Technical Reports Server (NTRS)

    Everett, H. U.; Myler, T. R.

    1975-01-01

    A FORTRAN coded computer program which determines secular variations in mean orbital elements of earth satellites and the lifetime of the orbit is described. The dynamical model treats a point mass satellite subject to solar and lunar disturbing gravitational fields, second, third and fourth harmonics of the earth's oblate potential, earth's atmospheric drag, and solar radiation pressure. Each of these disturbing functions may be selectively simulated. Data preparation instructions, a sample problem, and definitions of output quantities are included.

  5. Satellite observations of ethylene

    NASA Astrophysics Data System (ADS)

    Dolan, W.; Payne, V.; Kulawik, S. S.; Bowman, K. W.

    2015-12-01

    Ethylene (C2H4) is a trace gas commonly associated with boreal fire plumes and the petrochemical industry. It has a short lifetime (~1-2 days) in the troposphere due to its reaction with OH. Chemical destruction of ethylene in the atmosphere leads to the production of ozone precursors such as carbon monoxide (CO) and formaldehyde. The Tropospheric Emission Spectrometer (TES) is a Fourier Transform Spectrometer aboard the Aura satellite that measures thermal infrared radiances with high spectral resolution. Trace gas products retrieved routinely from TES spectra include O3, CO, H2O, HDO, CH4, NH3, HCOOH, CH3OH, with OCS and PAN to be included in the next data release. The TES spectra also includes a wealth of untapped information about other trace gasses including ethylene. Ethylene was first observed in TES spectra by Alvarado et al. (2011), though it has yet to be developed into an operational product. Our study focuses on the detection and initial quantitative estimates of ethylene in TES special observations taken in support of the 2008 ARCTAS mission. Initial observations of HCN in the spectra may provide a way to distinguish between fire plume and petrochemical derived ethylene. Results indicate a correlation between ethylene and CO in fresh fire plumes but not in older plumes, consistent with the gas's short lifetime. The approach adopted here to detect ethylene in the TES 2008 ARCTAS special observations can easily be expanded to larger datasets, including those from other thermal infrared sounders as well as to other trace gases.

  6. Satellite medical centers project

    NASA Astrophysics Data System (ADS)

    Aggarwal, Arvind

    2002-08-01

    World class health care for common man at low affordable cost: anywhere, anytime The project envisages to set up a national network of satellite Medical centers. Each SMC would be manned by doctors, nurses and technicians, six doctors, six nurses, six technicians would be required to provide 24 hour cover, each SMC would operate 24 hours x 7 days. It would be equipped with the Digital telemedicine devices for capturing clinical patient information and investigations in the form of voice, images and data and create an audiovisual text file - a virtual Digital patient. Through the broad band connectivity the virtual patient can be sent to the central hub, manned by specialists, specialists from several specialists sitting together can view the virtual patient and provide a specialized opinion, they can see the virtual patient, see the examination on line through video conference or even PCs, talk to the patient and the doctor at the SMC and controlle capturing of information during examination and investigations of the patient at the SMC - thus creating a virtual Digital consultant at the SMC. Central hub shall be connected to the doctors and consultants in remote locations or tertiary care hospitals any where in the world, thus creating a virtual hub the hierarchical system shall provide upgradation of knowledge to thedoctors in central hub and smc and thus continued medical education and benefit the patient thru the world class treatment in the smc located at his door step. SMC shall be set up by franchisee who shall get safe business opportunity with high returns, patients shall get Low cost user friendly worldclass health care anywhere anytime, Doctors can get better meaningful selfemplyment with better earnings, flexibility of working time and place. SMC shall provide a wide variety of services from primary care to world class Global consultation for difficult patients.

  7. ARJIS satellite demonstration project

    NASA Astrophysics Data System (ADS)

    Severance, Steve; Williams, Carl

    2005-06-01

    In 2003, the California Space Authority (CSA) was provided funding by the U. S. Congress through the Defense Appropriations Act to develop a project that would demonstrate the U.S. space enterprise capability that would contribute to the effectiveness of those engaged in Homeland Security. The project was given broad latitude in selecting the area of Homeland Security to be addressed and the nature of the space technology to be applied. CSA became aware of a nascent law enforcement data-sharing project in the San Diego region known as the Automated Regional Justice Information System (ARJIS). First developed by the police departments in San Diego, ARJIS is an innovative system that shares criminal justice information among 50 federal, state, and local agencies. ARJIS was completing a pilot project that enabled officers to receive information on handheld computers, which was transmitted wirelessly through cellular networks. The accessed information came from several databases that collectively contained the entire region's crime and arrest reports, traffic citations, and incidents, as well as state and county wants and warrants. The fundamental limitations that plague all cellular-based devices caught CSA's attention and resulted in a cooperative effort to harden the communications link between the patrol officer and critical data. The principal goal of the SATCOM development task was to create a proof-of-concept application that would use SATCOM links to augment the current ARJIS handheld wireless (cellular) capability. The successful technical demonstration and the positive support for satellite communications from the law enforcement community showed that this project filled a need-both for improved information sharing and for highly reliable communications systems.

  8. A multipurpose satellite ejection system

    NASA Technical Reports Server (NTRS)

    Moore, Michael B.

    1987-01-01

    A design is presented for a pneumatic ejection system capable of ejecting a spin stabilized satellite from the cargo bay of space vehicles. This system was orginally designed for use on the Spacelab 6 shuttle mission, but is now being considered for use with expendable rockets for launching satellites. The ejection system was designed to launch a 150 lb satellite at an initial ejection velocity of 32 ft/sec with a spin rate of 30 rev/min. The ejection system consists of a pneumatic cylinder, satellite retaining mechanism, and bearing assembly to allow the satellite to rotate during the spin up phase. As the cylinder is pressurized rapidly causing movement of the actuation piston, the mechanism automatically releases the spinning satellite by retracting a pneumatic locking pin and three spring loaded holddown pins. When the piston reaches the end of its stroke, it encounters a crushable aluminum honeycomb shock absorber which decelerates the piston and retaining mechanism. The assembly is designed for multiple uses except for the crushable shock absorber and pyrotechnic valves. The advantage of the design is discussed and patent no. and date given.

  9. The American mobile satellite system

    NASA Technical Reports Server (NTRS)

    Garner, William B.

    1990-01-01

    During 1989, the American Mobile Satellite Corporation (AMSC) was authorized to construct, launch, and operate satellites to provide mobile satellite services (MSS) to the U.S. and Puerto Rico. The AMSC has undertaken three major development programs to bring a full range of MSS services to the U.S. The first program is the space segment program that will result in the construction and launch of the satellites as well as the construction and installation of the supporting ground telemetry and command system. The second segment will result in the specification, design, development, construction, and installation of the Network Control System necessary for managing communications access to the satellites, and the specification and development of ground equipment for standard circuit switched and packet switched communications services. The third program is the Phase 1 program to provide low speed data services within the U.S. prior to availability of the AMSC satellites and ground segment. Described here are the present status and plans for these three programs as well as an update on related business arrangements and regulatory matters.

  10. Odyssey personal communications satellite system

    NASA Technical Reports Server (NTRS)

    Spitzer, Christopher J.

    1993-01-01

    The spectacular growth of cellular telephone networks has proved the demand for personal communications. Large regions of the world are too sparsely populated to be economically served by terrestrial cellular communications. Since satellites are well suited to this application, TRW filed with the FCC on May 31, 1993 for the Odyssey construction permit. Odyssey will provide high quality wireless communication services worldwide from satellites. These services will include: voice, data, paging, and messaging. Odyssey will be an economical approach to providing communications. A constellation of 12 satellites will be orbited in three, 55 deg. inclined planes at an altitude of 10,354 km to provide continuous coverage of designated regions. Two satellites will be visible anywhere in the world at all times. This dual visibility leads to high line-of-sight elevation angles, minimizing obstructions by terrain, trees and buildings. Each satellite generates a multibeam antenna pattern that divides its coverage area into a set of contiguous cells. The communications system employs spread spectrum CDMA on both the uplinks and downlinks. This signaling method permits band sharing with other systems and applications. Signal processing is accomplished on the ground at the satellite's 'Gateway' stations. The 'bent pipe' transponders accommodates different regional standards, as well as signaling changes over time. The low power Odyssey handset will be cellular compatible. Multipath fade protection is provided in the handset.

  11. Combined Release and Radiation Effects Satellite (CRRES) experiments data collection, analysis, and publication

    NASA Technical Reports Server (NTRS)

    Long, Terry N.; Alzmann, Melanie O.

    1992-01-01

    The Combined Release and Radiation Effects Satellite (CRRES) program experiments data collection, analysis, and publication activities are described. These activities were associated with both the satellite chemical release and a planned Puerto Rico sounding rocket campaign. To coordinate these activities, a working group meeting was organized and conducted.

  12. A satellite for demonstration of Panel Extension Satellite (PETSAT)

    NASA Astrophysics Data System (ADS)

    Sugawara, Yoshiki; Sahara, Hironori; Nakasuka, Shinichi; Greenland, Stephen; Morimoto, Takeshi; Koyama, Kanichi; Kobayashi, Chisato; Kikuchi, Hideaki; Okada, Takanori; Tanaka, Hidenori

    2008-07-01

    This paper presents the current status, configuration, architecture, and key technologies of SOHLA-2, the demonstration mission of the PETSAT (Panel ExTension SATellite) concept. The PETSAT proposal is for a modular satellite consisting of any number of unfolding functional panels. These panels are designed around an open architecture and connected through standardized interfaces. The interfaces between panels incorporate a reliable "plug-in" format, such that when combined, the integrated system takes on the intended satellite function in a redundant and distributed manner. By combining the different panel types in any number and configuration, flexibility to mission requirements is achieved. Some panels for performing basic satellite functions will be available as commercial-off-the-shelf components, and others custom developed dependent on the mission. During launch these panels are stowed in a folded low volume configuration, which is then extended on-orbit, realizing a satellite with a large area for the mounting of solar arrays, mission systems, extensible booms, or any other components. SOHLA-2 is both a concept demonstration and a lightning detection mission in the VHF band. It weighs less than 50 kg and consists of six panels: communication, attitude control, propulsion, mission, experiment and bus function. The bus function panel is based on the successful Cubesat XI developed at the University of Tokyo and this acts as the manager of the technology demonstration aspects for the mission. By basing the architecture upon a proven technology, the reliability of the satellite is increased. It is intended that the satellite be launched in early 2008.

  13. Satellites You Can See for Homework

    ERIC Educational Resources Information Center

    Broderick, Stephen

    2012-01-01

    Artificial satellites are easily observed most nights when the weather is fine. The website called "Heavens Above" at www.heavens-above.com will help locate these satellites flying over one's location. It also includes how bright they will appear. The direction of travel of each satellite in the night sky also indicates the type of satellite. For…

  14. Interferometric imaging of geostationary satellites

    NASA Astrophysics Data System (ADS)

    Armstrong, J. T.; Baines, E. K.; Hindsley, R. B.; Schmitt, H. R.; Restaino, S. R.; Jorgensen, A. M.; Mozurkewich, D.

    2012-06-01

    Even the longest geosatellite, at 40 m, subtends only 0.2 arcsec (1 microradian). Determining structure and orientation with 10 cm resolution requires a 90 m telescope at visual wavelengths, or an interferometer. We de- scribe the application of optical interferometry to observations of complex extended targets such as geosatellites, and discuss some of its challenges. We brie y describe our Navy Optical Interferometer (NOI) group's eorts toward interferometric observations of geosatellites, including the rst interferometric detection of a geosatellite. The NOI observes in 16 spectral channels (550{850 nm) using up to six 12-cm apertures, with baselines (separa- tions between apertures) of 16 to 79 m. We detected the geosatellite DirecTV-9S during glint seasons in March 2008 and March 2009, using a single 16 m baseline (resolution 1:6 m). Fringes on a longer baseline were too weak because the large-scale structure was over-resolved. The fringe strengths are consistent with a combination of two size scales, 1:3 m and & 3:5 m. Our near term NOI work is directed toward observing geosatellites with three or more 10 to 15 m baselines, using closure phase measurements to remove atmospheric turbulence eects and coherent data averaging to increase the SNR. Beyond the two- to three-year time frame, we plan to install larger apertures (1.4 and 1.8 m), allowing observations outside glint season, and to develop baseline bootstrap- ping, building long baselines from chains of short baselines, to avoid over-resolution while increasing maximum resolution. Our ultimate goal is to develop the design parameters for dedicated satellite imaging interferometry.

  15. GROUP INEQUALITY

    PubMed Central

    Bowles, Samuel; Loury, Glenn C.; Sethi, Rajiv

    2014-01-01

    We explore the combined effect of segregation in social networks, peer effects, and the relative size of a historically disadvantaged group on the incentives to invest in market-rewarded skills and the dynamics of inequality between social groups. We identify conditions under which group inequality will persist in the absence of differences in ability, credit constraints, or labor market discrimination. Under these conditions, group inequality may be amplified even if initial group differences are negligible. Increases in social integration may destabilize an unequal state and make group equality possible, but the distributional and human capital effects of this depend on the demographic composition of the population. When the size of the initially disadvantaged group is sufficiently small, integration can lower the long-run costs of human capital investment in both groups and result in an increase the aggregate skill share. In contrast, when the initially disadvantaged group is large, integration can induce a fall in the aggregate skill share as the costs of human capital investment rise in both groups. We consider applications to concrete cases and policy implications. PMID:25554727

  16. Telemetry Data Collection from Oscar Satellite

    NASA Technical Reports Server (NTRS)

    Haddock, Paul C.; Horan, Stephen

    1998-01-01

    This paper discusses the design, configuration, and operation of a satellite station built for the Center for Space Telemetering and Telecommunications Laboratory in the Klipsch School of Electrical and Computer Engineering Engineering at New Mexico State University (NMSU). This satellite station consists of a computer-controlled antenna tracking system, 2m/70cm transceiver, satellite tracking software, and a demodulator. The satellite station receives satellite,telemetry, allows for voice communications, and will be used in future classes. Currently this satellite station is receiving telemetry from an amateur radio satellite, UoSAT-OSCAR-11. Amateur radio satellites are referred to as Orbiting Satellites Carrying Amateur Radio (OSCAR) satellites as discussed in the next section.

  17. Shadow imaging of geosynchronous satellites

    NASA Astrophysics Data System (ADS)

    Douglas, Dennis Michael

    Geosynchronous (GEO) satellites are essential for modern communication networks. If communication to a GEO satellite is lost and a malfunction occurs upon orbit insertion such as a solar panel not deploying there is no direct way to observe it from Earth. Due to the GEO orbit distance of ~36,000 km from Earth's surface, the Rayleigh criteria dictates that a 14 m telescope is required to conventionally image a satellite with spatial resolution down to 1 m using visible light. Furthermore, a telescope larger than 30 m is required under ideal conditions to obtain spatial resolution down to 0.4 m. This dissertation evaluates a method for obtaining high spatial resolution images of GEO satellites from an Earth based system by measuring the irradiance distribution on the ground resulting from the occultation of the satellite passing in front of a star. The representative size of a GEO satellite combined with the orbital distance results in the ground shadow being consistent with a Fresnel diffraction pattern when observed at visible wavelengths. A measurement of the ground shadow irradiance is used as an amplitude constraint in a Gerchberg-Saxton phase retrieval algorithm that produces a reconstruction of the satellite's 2D transmission function which is analogous to a reverse contrast image of the satellite. The advantage of shadow imaging is that a terrestrial based redundant set of linearly distributed inexpensive small telescopes, each coupled to high speed detectors, is a more effective resolved imaging system for GEO satellites than a very large telescope under ideal conditions. Modeling and simulation efforts indicate sub-meter spatial resolution can be readily achieved using collection apertures of less than 1 meter in diameter. A mathematical basis is established for the treatment of the physical phenomena involved in the shadow imaging process. This includes the source star brightness and angular extent, and the diffraction of starlight from the satellite

  18. Distance Learning via Satellite Begins with Analysis of the Users.

    ERIC Educational Resources Information Center

    Bunting, Larry

    A study of administrators, teachers, and students at 19 community colleges was conducted in order to better understand the individual groups served by satellite technology in distance education programs. Along with demographic information, the following issues were investigated: (1) learning styles most commonly used at each institution; (2)…

  19. Satellite Applications for K-12 Geoscience Education

    NASA Astrophysics Data System (ADS)

    Mooney, M.; Ackerman, S.; Lettvin, E.; Emerson, N.; Whittaker, T. M.

    2007-12-01

    This presentation will highlight interactive on-line curriculum developed at the Cooperative Institute for Meteorological Satellite Studies (CIMSS) at the University of Wisconsin in Madison. CIMSS has been on the forefront of educational software design for over two decades, routinely integrating on-line activities into courses on satellite remote sensing. In 2006, CIMSS began collaborating with education experts and researchers from the University of Washington to create an NSF-funded distance learning course for science teachers called Satellite Applications for Geoscience Education. This course includes numerous web-based learning activities, including a distance education tool called VISITview which allows instructors to connect with multiple students simultaneously to conduct a lesson. Developed at CIMSS to facilitate training of National Weather Service forecasters economically and remotely, VISITview is especially effective for groups of people discussing and analyzing maps or images interactively from many locations. Along with an on-line chat function, VISITview participants can use a speaker phone or a networked voice-enabled application to create a learning environment similar to a traditional classroom. VISITview will be used in two capacities: first, instructors will convey topics of current relevance in geoscience disciplines via VISITview. Second, the content experts will participate in "virtual visits" to the classrooms of the educators who take the course for full credit. This will enable scientists to interact with both teachers and students to answer questions and discuss exciting or inspiring examples that link satellite data to their areas of research. As long as a school has Internet access, an LCD projector and a speakerphone, VISITview sessions can be shared with an entire classroom. The geoscientists who developed material for the course and conducting VISITview lectures include a geologist from the University of Wisconsin-Richland, an

  20. A review of satellite data algorithms for studies of the land surface

    NASA Technical Reports Server (NTRS)

    Sellers, P. J.; Rasool, S. I.; Bolle, H.-J.

    1990-01-01

    The major groups of algorithms used to convert satellite data into land-surface climatological parameters are reviewed. The International Satellite Land-Surface Climatology Project (ISLSCP) and the Satellite Data Algorithm Workshop are described. ISLSCP was initiated to address the research problems associated with interpretation and utilization of satellite data over the earth's land surface. The proceedings of a workshop sponsored by ISLSCP to investigate the state and potential of satellite sensor output into surface parameters is presented. The current status of algorithms used to determine land-surface parameters is assessed; the methodologies that ultilize these parameters and other data for estimates of the surface energy balance are reviewed; and a preliminary assessment of the effort required to construct an operational system for the routine processing of satellite data into land-surface parameters is made.

  1. Linked Autonomous Interplanetary Satellite Orbit Navigation

    NASA Technical Reports Server (NTRS)

    Parker, Jeffrey S.; Anderson, Rodney L.; Born, George H.; Leonard, Jason M.; McGranaghan, Ryan M.; Fujimoto, Kohei

    2013-01-01

    A navigation technology known as LiAISON (Linked Autonomous Interplanetary Satellite Orbit Navigation) has been known to produce very impressive navigation results for scenarios involving two or more cooperative satellites near the Moon, such that at least one satellite must be in an orbit significantly perturbed by the Earth, such as a lunar halo orbit. The two (or more) satellites track each other using satellite-to-satellite range and/or range-rate measurements. These relative measurements yield absolute orbit navigation when one of the satellites is in a lunar halo orbit, or the like. The geometry between a lunar halo orbiter and a GEO satellite continuously changes, which dramatically improves the information content of a satellite-to-satellite tracking signal. The geometrical variations include significant out-of-plane shifts, as well as inplane shifts. Further, the GEO satellite is almost continuously in view of a lunar halo orbiter. High-fidelity simulations demonstrate that LiAISON technology improves the navigation of GEO orbiters by an order of magnitude, relative to standard ground tracking. If a GEO satellite is navigated using LiAISON- only tracking measurements, its position is typically known to better than 10 meters. If LiAISON measurements are combined with simple radiometric ground observations, then the satellite s position is typically known to better than 3 meters, which is substantially better than the current state of GEO navigation. There are two features of LiAISON that are novel and advantageous compared with conventional satellite navigation. First, ordinary satellite-to-satellite tracking data only provides relative navigation of each satellite. The novelty is the placement of one navigation satellite in an orbit that is significantly perturbed by both the Earth and the Moon. A navigation satellite can track other satellites elsewhere in the Earth-Moon system and acquire knowledge about both satellites absolute positions and velocities

  2. Relativity in Satellite Laser Ranging

    NASA Astrophysics Data System (ADS)

    Ries, John C.

    2009-05-01

    Satellite laser ranging (SLR) is the measurement of the round-trip light time of ultra-short laser pulses to satellites deploying specifically designed retroreflectors. The ranging data are used to determine cm-precision satellite orbits, temporal variations in the Earth's gravity field, mm/yr accuracy determinations of station motion on a global scale, and fundamental physical constants. The SLR stations form an important part of the international network of space geodetic observatories that define and maintain the International Terrestrial Reference System. Starting in 1964, the precision of satellite laser ranging has improved from a few meters to a few mm for the better stations. With a measurement accuracy better than the part-per-billion level, the effects General Relativity must be considered. These include additional perturbations to the orbit dynamics, corrections to the round-trip light-time computation, and fundamental aspects of space-time in the definition of the geocentric reference frame. While these effects are significant, they are generally not large enough to provide useful tests of General Relativity. An important exception, however, is the relativistic prediction of the Lense-Thirring orbit precession, i.e the effect of `frame-dragging’ on the satellite orbit due to the spinning Earth's mass. While the signal is large enough to be easily observed with satellite laser ranging, the Lense-Thirring measurement uncertainty is limited by the knowledge of the even zonal harmonics of the Earth's gravity field that also produce Newtonian secular orbit precessions. However, this problem has been overcome with the dramatically improved models resulting from the joint NASA-DLR Gravity Recovery and Climate Experiment (GRACE) mission. Using laser ranging to the LAGEOS satellites, it is possible to confirm the General Relativity prediction of the Lense-Thirring precession with an uncertainty better than 15%. This research was supported by the National

  3. Using Cell Phones From Satellites

    NASA Technical Reports Server (NTRS)

    Horan, Stephen

    2000-01-01

    During the past several years, an interest has grown in using commercial telecommunications techniques to supply Telemetry and Command (T&C) services. Recently, the National Aeronautics and Space Administration (NASA) Space Operations Management Office (SOMO) has outlined plans to utilize satellite-based telecommunications services to support space operations in space missions over the next several decades. NASA currently obtains the bulk of its telecommunications services for earth-orbiting satellites via the existing government-owned and controlled Space Network (SN) system. This system consists of the constellation of Tracking and Data Relay Satellites (TDRS) in Geostationary Earth Orbit (GEO) and the associated ground terminals and communications intrastructure. This system is valuable and effective for scientific satellites costing over one million dollars. However, for smaller satellites, this system becomes problematic due to the cost of transponders and support infrastructure. The nominal transponders for using the TDRS cannot be obtained for a cost in dollars, and size, weight, or power that the 3 Corner Satellite project can afford. For these types of nanosatellite missions, alternatives that fit the mission cost and satellite profiles are needed. In particular, low-cost access using existing commercial infrastructure would be useful to mission planners. In particular, the ability to obtain low data rate T&C services would be especially valuable. The nanosatellites generally have low T&C requirements and therefore would benefit from using commercial services that could operate in the 2400 bps - 9600 bps range, especially if contact times longer than the 5 - 10 minute ground station passes could be found.

  4. Weather Satellite Enterprise Information Chain

    NASA Astrophysics Data System (ADS)

    Jamilkowski, M. L.; Grant, K. D.; Miller, S. W.; Cochran, S.

    2015-12-01

    NOAA & NASA are acquiring the next-generation civilian operational weather satellite: Joint Polar Satellite System (JPSS). Contributing the afternoon orbit & ground system (GS) to replace current NOAA POES Satellites, its sensors will collect meteorological, oceanographic & climatological data. The JPSS Common Ground System (CGS), consisting of C3 and IDP segments, is developed by Raytheon. It now flies the Suomi National Polar-orbiting Partnership (S-NPP) satellite, transferring data between ground facilities, processing them into environmental products for NOAA weather centers, and expanding to support JPSS-1 in 2017. As a multi-mission system, CGS provides combinations of C3, data processing, and product delivery for numerous NASA, NOAA, DoD and international missions.The CGS provides a wide range of support to a number of missions: Command and control and mission management for the S-NPP mission today, expanding this support to the JPSS-1 satellite mission in 2017 Data acquisition for S-NPP, the JAXA's Global Change Observation Mission - Water (GCOM-W1), POES, and the Defense Meteorological Satellite Program (DMSP) and Coriolis/WindSat for the DoD Data routing over a global fiber network for S-NPP, JPSS-1, GCOM-W1, POES, DMSP, Coriolis/WindSat, NASA EOS missions, MetOp for EUMETSAT and the National Science Foundation Environmental data processing and distribution for S-NPP, GCOM-W1 and JPSS-1 The CGS plays a key role in facilitating the movement and value-added enhancement of data all the way from satellite-based sensor data to delivery to the consumers who generate forecasts and produce watches and warnings. This presentation will discuss the information flow from sensors, through data routing and processing, and finally to product delivery. It will highlight how advances in architecture developed through lessons learned from S-NPP and implemented for JPSS-1 will increase data availability and reduce latency for end user applications.

  5. Minuteman 2 launched small satellite

    NASA Technical Reports Server (NTRS)

    Chan, Sunny; Hinders, Kriss; Martin, Trent; Mcmillian, Shandy; Sharp, Brad; Vajdos, Greg

    1994-01-01

    The goal of LEOSat Industries' Spring 1994 project was to design a small satellite that has a strong technology demonstration or scientific justification and incorporates a high level of student involvement. The satellite is to be launched into low earth orbit by the converted Minuteman 2 satellite launcher designed by Minotaur Designs, Inc. in 1993. The launch vehicle shroud was modified to a height of 90 inches, a diameter of 48 inches at the bottom and 35 inches at the top for a total volume of 85 cubic feet. The maximum allowable mass of the payload is about 1100 lb., depending on the launch site, orbit altitude, and inclination. The satellite designed by LEOSat Industries is TerraSat, a remote-sensing satellite that will provide information for use in space-based earth studies. It will consist of infrared and ultraviolet/visible sensors similar to the SDI-developed sensors being tested on Clementine. The sensors will be mounted on the Defense Systems, Inc. Standard Satellite-1 spacecraft bus. LEOSat has planned for two satellites orbiting the Earth with trajectories similar to that of LANDSAT 5. The semi-major axis is 7080 kilometers, the eccentricity is 0, and the inclination is 98.2 degrees. The estimated mass of TerraSat is 145 kilograms and the estimated volume is 1.8 cubic meters. The estimated cost of TerraSat is $13.7 million. The projected length of time from assembly of the sensors to launch of the spacecraft is 13 months.

  6. Autonomous satellite navigation methods using the Global Positioning Satellite System

    NASA Technical Reports Server (NTRS)

    Murata, M.; Tapley, B. D.; Schutz, B. E.

    1982-01-01

    This investigation considers the problem of autonomous satellite navigation using the NAVSTAR Global Positioning System (GPS). The major topics covered include the design, implementation, and validation of onboard navigation filter algorithms by means of computer simulations. The primary errors that the navigation filter design must minimize are computational effects and modeling inaccuracies due to limited capability of the onboard computer. The minimization of the effect of these errors is attained by applying the sequential extended Kalman filter using a factored covariance implementation with Q-matrix or dynamical model compensations. Peformance evaluation of the navigation filter design is carried out using both the CDC Cyber 170/750 computer and the PDP-11/60 computer. The results are obtained assuming the Phase I GPS constellation, consisting of six satellites, and a Landsat-D type spacecraft as the model for the user satellite orbit.

  7. Phoebe and the Icy Saturnian Satellites: Implications for Satellite Origins

    NASA Astrophysics Data System (ADS)

    Mosqueira, I.; Estrada, P. R.

    2004-11-01

    Phoebe's retrograde, eccentric and inclined orbit marks it as an object captured from heliocentric orbit. Accordingly, its composition may be indicative of its origin in the solar nebula. Analogous arguments have been made extensively in connection with the origin of Pluto-Charon (see, e.g., McKinnon et al. 1997) as well as Triton (McKinnon and Mueller 1989). Indeed, the demarcation between nebula and subnebula objects has led a number of workers (see, e.g., Johnson et al. 1987; Lunine et al. 1993; Podolak et al. 1993) to argue that the regular satellites of the giant planets did not derive the bulk of their material directly from heliocentric orbit. The recent Cassini flyby of Phoebe has yielded a mass for this object of GM = 0.5527 ± 0.001 km3/s2 Jacobson et al. 2004 (this conference). Its density of 1.6 g/cm3 indicates a rock to ice ratio of at least 50 % (Porco et al. 2004; Science, to be submitted). Phoebe's high rock/ice ratio when compared to the icy Saturnian satellites reinforces the argument that Phoebe is an object that formed in heliocentric orbit and became captured. Yet, given that it may be misleading to lump together satellites with quite different formation histories, we refine the comparison on the basis of models for regular satellite formation. Because it derives condensables directly from heliocentric orbit and fails to consider planetesimals, the model of Canup and Ward (2002) does not provide a context for understanding such compositional differences. We will therefore discuss two models of satellite formation we are developing, which differ mainly in their treatment of turbulence (decaying vs steady). In both models the inner (located inside Titan's orbit), icy Saturnian satellites represent a second generation of objects. Mosqueira and Estrada (2003a,b) has these satellites forming 104-10^5 years after Titan as the disk became optically thin and water rich due to preferential gas drag loss of silicates as Saturn cooled. On the other hand

  8. Phoebe and the Icy Saturnian Satellites: Implications for Satellite Origins

    NASA Astrophysics Data System (ADS)

    Mosqueira, I.; Estrada, P. R.

    2004-12-01

    Phoebe's retrograde, eccentric and inclined orbit marks it as an object captured from heliocentric orbit. Accordingly, its composition may be indicative of its origin in the solar nebula. Analogous arguments have been made extensively in connection with the origin of Pluto-Charon (see, e.g., McKinnon et al. 1997) as well as Triton (McKinnon and Mueller 1989). Indeed, the demarcation between nebula and subnebula objects has led a number of workers (see, e.g., Johnson et al. 1987; Lunine et al. 1993; Podolak et al. 1993) to argue that the regular satellites of the giant planets did not derive the bulk of their material directly from heliocentric orbit. The recent Cassini flyby of Phoebe has yielded a mass for this object of GM = 0.5527 ± 0.001 km3/s2 Jacobson et al. 2004. Its density of 1.6 g/cm3 indicates a rock to ice ratio of at least 50 % (Porco et al. 2004; Science, to be submitted). Phoebe's high rock/ice ratio when compared to the icy Saturnian satellites reinforces the argument that Phoebe is an object that formed in heliocentric orbit and became captured. Yet, given that it may be misleading to lump together satellites with quite different formation histories, we refine the comparison on the basis of models for regular satellite formation. Because it derives condensables directly from heliocentric orbit and fails to consider planetesimals, the model of Canup and Ward (2002) does not provide a context for understanding such compositional differences. We will therefore discuss two models of satellite formation we are developing, which differ mainly in their treatment of turbulence (decaying vs steady). In both models the inner (located inside Titan's orbit), icy Saturnian satellites represent a second generation of objects. Mosqueira and Estrada (2003a,b) has these satellites forming 104-10^5 years after Titan as the disk became optically thin and water rich due to preferential gas drag loss of silicates as Saturn cooled. On the other hand, the gas

  9. A novel retro-inverso peptide inhibitor reduces amyloid deposition, oxidation and inflammation and stimulates neurogenesis in the APPswe/PS1ΔE9 mouse model of Alzheimer's disease.

    PubMed

    Parthsarathy, Vadivel; McClean, Paula L; Hölscher, Christian; Taylor, Mark; Tinker, Claire; Jones, Glynn; Kolosov, Oleg; Salvati, Elisa; Gregori, Maria; Masserini, Massimo; Allsop, David

    2013-01-01

    Previously, we have developed a retro-inverso peptide inhibitor (RI-OR2, rGffvlkGr) that blocks the in vitro formation and toxicity of the Aβ oligomers which are thought to be a cause of neurodegeneration and memory loss in Alzheimer's disease. We have now attached a retro-inverted version of the HIV protein transduction domain 'TAT' to RI-OR2 to target this new inhibitor (RI-OR2-TAT, Ac-rGffvlkGrrrrqrrkkrGy-NH(2)) into the brain. Following its peripheral injection, a fluorescein-labelled version of RI-OR2-TAT was found to cross the blood brain barrier and bind to the amyloid plaques and activated microglial cells present in the cerebral cortex of 17-months-old APPswe/PS1ΔE9 transgenic mice. Daily intraperitoneal injection of RI-OR2-TAT (at 100 nmol/kg) for 21 days into 10-months-old APPswe/PS1ΔE9 mice resulted in a 25% reduction (p<0.01) in the cerebral cortex of Aβ oligomer levels, a 32% reduction (p<0.0001) of β-amyloid plaque count, a 44% reduction (p<0.0001) in the numbers of activated microglial cells, and a 25% reduction (p<0.0001) in oxidative damage, while the number of young neurons in the dentate gyrus was increased by 210% (p<0.0001), all compared to control APPswe/PS1ΔE9 mice injected with vehicle (saline) alone. Our data suggest that oxidative damage, inflammation, and inhibition of neurogenesis are all a downstream consequence of Aβ aggregation, and identify a novel brain-penetrant retro-inverso peptide inhibitor of Aβ oligomer formation for further testing in humans as a potential disease-modifying treatment for Alzheimer's disease.

  10. Changes in the brain and plasma Aβ peptide levels with age and its relationship with cognitive impairment in the APPswe/PS1dE9 mouse model of Alzheimer's disease.

    PubMed

    Izco, M; Martínez, P; Corrales, A; Fandos, N; García, S; Insua, D; Montañes, M; Pérez-Grijalba, V; Rueda, N; Vidal, V; Martínez-Cué, C; Pesini, P; Sarasa, M

    2014-03-28

    Double transgenic mice expressing mutant amyloid precursor protein (APPswe) and mutant presenilin 1 (PS1dE9) are a model of Alzheimer-type amyloidosis and are widely used in experimental studies. In the present work, the relationships between brain and plasma amyloid-β peptide (Aβ) levels and cognitive impairments were examined in male APPswe/PS1dE9 double transgenic mice at different ages. When compared with non-transgenic littermates, APPswe/PS1dE9 mice exhibited significant learning deficits from the age of 6months (M6), which were aggravated at later stages of life (M8 and M12). Sporadic brain amyloid plaques were observed in mice as early as M3 and progressively increased in number and size up to M12. A similar increase was observed in brain insoluble Aβ levels as assessed by enzyme-linked immunosorbent assay (ELISA). In particular, the levels of brain insoluble Aβ peptides rose steeply from M4 to M6. Interestingly, this pronounced amyloid deposition was accompanied by a temporary fall in the concentration of brain soluble and membrane-bound Aβ peptides at M6 that rose again at M8 and M12. The plasma levels of Aβ40 and Aβ42 decreased with advancing age up to M8, when they stabilized at M12. This decrease in plasma Aβ levels coincided with the observed increase in insoluble brain Aβ levels. These results could be useful for developing plasma Aβ levels as possible biomarkers of the cerebral amyloidosis and provide advances in the knowledge of the Aβ peptide biochemical changes that occur in the brain of Alzheimer's disease patients.

  11. Stream Gauges and Satellite Measurements

    NASA Astrophysics Data System (ADS)

    Alsdorf, D. E.

    2010-12-01

    Satellite measurements should not be viewed as a replacement for stream gauges. However, occasionally it is suggested that because satellite-based measurements can provide river discharge, a motivation for satellite approaches is an increasing lack of stream gauges. This is an argument for more stream gauges, but not necessarily for satellite measurements. Rather, in-situ and spaceborne methods of estimating discharge are complementary. Stream gauges provide frequent measurements at one point in the river reach whereas satellites have the potential to measure throughout all reaches but at orbital repeat intervals of days to weeks. The Surface Water and Ocean Topography satellite mission (SWOT) is an opportunity to further develop these complements. The motivation for SWOT, and indeed for any satellite based method of estimating discharge, should not be as a replacement for stream gauges. Scientific and application uses should motivate the measurements. For example, understanding floods with their dynamic water surfaces are best sampled from remote platforms that provide water surface elevations throughout the floodwave. As another example, today’s water and energy balance models are giving outputs at increasing spatial resolution and are making use of water surface elevations throughout the modeled basin. These models require a similar resolution in the calibrating and validating observations. We should also be aware of practical limitations. In addition to providing spatially distributed hydrodynamic measurements on rivers, SWOT will be able to measure storage changes in the estimated 30 million lakes in the world that are larger than a hectare. Knowing the storage changes in these lakes is especially important in certain regions such as the Arctic but gauging even a small fraction of these is impractical. Another motivator for satellite methods is that even in the presence of stream gauges, discharge data is not always well shared throughout all countries

  12. Observing iodine monoxide from satellite

    NASA Astrophysics Data System (ADS)

    Schoenhardt, Anja; Richter, Andreas; Begoin, Mathias; Wittrock, Folkard; Burrows, John P.

    Iodine and iodine monoxide (IO) belong to the group of reactive halogen species, and they may impact on atmospheric chemical composition and the radiation budget. Vice versa, sur-rounding conditions may influence the emissions and pathways of iodine compounds. Although atmospheric amounts of iodine are typically fairly small, the impact may still be substantial. Iodine radicals are photolytically released from precursors and may then cause catalytic ozone depletion. In this reaction with ozone, IO is produced, a molecule which plays a central role in the iodine cycling. Via self reactions of IO, higher iodine oxides form and initiate the formation of new particles, which may change the atmospheric radiation balance. Apart from that, many living species, including human beings, vertebrates in general, but also micro-and macroalgae species, e.g., depend on the supply with iodine. Consequently, it is necessary to understand the cycling of iodine through the different components of the Earth system. Although increas-ing research effort in the form of field, laboratory and modeling studies has strongly improved our knowledge and understanding of iodine abundances and impact, still many open questions remain. The relevance of iodine on a global scale is not well known yet; sources are not well quantified and release processes are not fully understood. Since recently, IO may be observed from space by the SCIAMACHY instrument on the EN-VISAT satellite, which is in a near-polar, sun-synchronous orbit. Nadir observations from SCIAMACHY have been analysed for the IO absorption signature in the visible wavelength range for several mission years. IO amounts are typically close to the limit of detectability of SCIAMACHY. Detecting such small quantities, careful attention needs to be paid to system-atic errors, spectral correlations and resulting retrieval artefacts. Subsequently, appropriate temporal averaging is utilised to improve the signal-to-noise ratio. The resulting

  13. Dust collection on serviceable satellites

    NASA Technical Reports Server (NTRS)

    Nuth, J. A., III

    1986-01-01

    One rationale for the Space Shuttle program which was dramatically realized during the repair of the Solar Maximum Mission (SMM) is the efficiency of in-orbit satellite servicing. An unexpected benefit of this repair mission was the return of parts of the Solar Max satellite which had been exposed for four years to the space environment. Studies conducted on these parts have yielded valuable data on the micrometeorite flux and composition at shuttle altitudes during this time period. The scientific results from studies of the cosmic dust component of the observed particle impacts are not yet complete but it is clear from the preliminary data available that such studies will be a valuable adjunct to the studies of cosmic dust particles collected in the atmosphere. The success of the initial studies of particles collected during repairs of the SMM spacecraft on a surface not specifically designed as a particle collector nor retrieved in a manner intended to minimize or eliminate local contamination raises the possibility that even more interesting results might be obtained if serviceable satellites were initially designed with these objectives in mind. All designs for modern satellites utilize some form of thermal blanket material in order to minimize thermal stresses inside the spacecraft. It is proposed that all future satellites be designed with standardized removeable sections of thermal blanket material which could be replaced during on-orbit servicing and returned to earth for detailed study.

  14. Visualizing Airborne and Satellite Imagery

    NASA Technical Reports Server (NTRS)

    Bierwirth, Victoria A.

    2011-01-01

    Remote sensing is a process able to provide information about Earth to better understand Earth's processes and assist in monitoring Earth's resources. The Cloud Absorption Radiometer (CAR) is one remote sensing instrument dedicated to the cause of collecting data on anthropogenic influences on Earth as well as assisting scientists in understanding land-surface and atmospheric interactions. Landsat is a satellite program dedicated to collecting repetitive coverage of the continental Earth surfaces in seven regions of the electromagnetic spectrum. Combining these two aircraft and satellite remote sensing instruments will provide a detailed and comprehensive data collection able to provide influential information and improve predictions of changes in the future. This project acquired, interpreted, and created composite images from satellite data acquired from Landsat 4-5 Thematic Mapper (TM) and Landsat 7 Enhanced Thematic Mapper plus (ETM+). Landsat images were processed for areas covered by CAR during the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCT AS), Cloud and Land Surface Interaction Campaign (CLASIC), Intercontinental Chemical Transport Experiment-Phase B (INTEXB), and Southern African Regional Science Initiative (SAFARI) 2000 missions. The acquisition of Landsat data will provide supplemental information to assist in visualizing and interpreting airborne and satellite imagery.

  15. Low Earth orbit communications satellite

    NASA Technical Reports Server (NTRS)

    Moroney, D.; Lashbrook, D.; Mckibben, B.; Gardener, N.; Rivers, T.; Nottingham, G.; Golden, B.; Barfield, B.; Bruening, J.; Wood, D.

    1992-01-01

    A current thrust in satellite communication systems considers a low-Earth orbiting constellations of satellites for continuous global coverage. Conceptual design studies have been done at the time of this design project by LORAL Aerospace Corporation under the program name GLOBALSTAR and by Motorola under their IRIDIUM program. This design project concentrates on the spacecraft design of the GLOBALSTAR low-Earth orbiting communication system. Overview information on the program was gained through the Federal Communications Commission licensing request. The GLOBALSTAR system consists of 48 operational satellites positioned in a Walker Delta pattern providing global coverage and redundancy. The operational orbit is 1389 km (750 nmi) altitude with eight planes of six satellites each. The orbital planes are spaced 45 deg., and the spacecraft are separated by 60 deg. within the plane. A Delta 2 launch vehicle is used to carry six spacecraft for orbit establishment. Once in orbit, the spacecraft will utilize code-division multiple access (spread spectrum modulation) for digital relay, voice, and radio determination satellite services (RDSS) yielding position determination with accuracy up to 200 meters.

  16. Chartering Launchers for Small Satellites

    NASA Astrophysics Data System (ADS)

    Hernandez, Daniel

    The question of how to launch small satellites has been solved over the years by the larger launchers offering small satellites the possibility of piggy-backing. Specific fixtures have been developed and commercialized: Arianespace developed the ASAP interface, the USAF studied ESPA, NASA has promoted Shuttle launch possibilities, Russian authorities and companies have been able to find solutions with many different launchers... It is fair to say that most launcher suppliers have worked hard and finally often been able to find solutions to launch most small satellites into orbit. It is also true, however, that most of these small satellites were technology demonstration missions capable of accepting a wide range of orbit and launch characteristics: orbit altitude and inclination, launch date, etc. In some cases the small satellite missions required a well-defined type of orbit and have therefore been obliged to hire a small launcher on which they were the prime passenger. In our paper we would like to propose an additional solution to all these possibilities: launchers could plan well in advance (for example about 3 years), trips to precisely defined orbits to allow potential passengers to organize themselves and be ready on the D-Day. On the scheduled date the chartered launcher goes to the stated orbit while on another date, another chartered launcher goes to another orbit. The idea is to organize departures for space like trains or airplanes leaving on known schedules for known destinations.

  17. Space Solar Power: Satellite Concepts

    NASA Technical Reports Server (NTRS)

    Little, Frank E.

    1999-01-01

    Space Solar Power (SSP) applies broadly to the use of solar power for space related applications. The thrust of the NASA SSP initiative is to develop concepts and demonstrate technology for applying space solar power to NASA missions. Providing power from satellites in space via wireless transmission to a receiving station either on earth, another celestial body or a second satellite is one goal of the SSP initiative. The sandwich design is a satellite design in which the microwave transmitting array is the front face of a thin disk and the back of the disk is populated with solar cells, with the microwave electronics in between. The transmitter remains aimed at the earth in geostationary orbit while a system of mirrors directs sunlight to the photovoltaic cells, regardless of the satellite's orientation to the sun. The primary advantage of the sandwich design is it eliminates the need for a massive and complex electric power management and distribution system for the satellite. However, it requires a complex system for focusing sunlight onto the photovoltaic cells. In addition, positioning the photovoltaic array directly behind the transmitting array power conversion electronics will create a thermal management challenge. This project focused on developing designs and finding emerging technology to meet the challenges of solar tracking, a concentrating mirror system including materials and coatings, improved photovoltaic materials and thermal management.

  18. Research Supporting Satellite Communications Technology

    NASA Technical Reports Server (NTRS)

    Horan Stephen; Lyman, Raphael

    2005-01-01

    This report describes the second year of research effort under the grant Research Supporting Satellite Communications Technology. The research program consists of two major projects: Fault Tolerant Link Establishment and the design of an Auto-Configurable Receiver. The Fault Tolerant Link Establishment protocol is being developed to assist the designers of satellite clusters to manage the inter-satellite communications. During this second year, the basic protocol design was validated with an extensive testing program. After this testing was completed, a channel error model was added to the protocol to permit the effects of channel errors to be measured. This error generation was used to test the effects of channel errors on Heartbeat and Token message passing. The C-language source code for the protocol modules was delivered to Goddard Space Flight Center for integration with the GSFC testbed. The need for a receiver autoconfiguration capability arises when a satellite-to-ground transmission is interrupted due to an unexpected event, the satellite transponder may reset to an unknown state and begin transmitting in a new mode. During Year 2, we completed testing of these algorithms when noise-induced bit errors were introduced. We also developed and tested an algorithm for estimating the data rate, assuming an NRZ-formatted signal corrupted with additive white Gaussian noise, and we took initial steps in integrating both algorithms into the SDR test bed at GSFC.

  19. Satellite dual antenna pointing system

    NASA Technical Reports Server (NTRS)

    Keigler, John E. (Inventor); Hartshorne, Frank A. (Inventor)

    1986-01-01

    A satellite antenna pointing system for separately pointing separated transmit and receive high gain antenna systems includes means for separately and sequentially applying a beacon signal to the transmit and receive antenna systems and a broad beam width antenna which has a coverage area greater than the overall coverage region of the spot beam antenna systems. The system includes ground stations located at or near the periphery of the overall coverage region adapted to receive these beacon signals. At a central control station these beacon signals are compared to provide first signals proportional to the ratio of said beacon signals received from said transmit antenna system and said broad beam width antenna and second signals proportional to the ratio of said beacon signals received from said satellite receive antenna system and said broad beam width antenna. The central station generates from said first signals transmit antenna control signals which are sent to the satellite to control the orientation of said transmit antenna system. Likewise, the central control station generates from the second signals receiver antenna control signals which are applied to the satellite to control the orientation of the satellite receive antenna system.

  20. Are rotating planes of satellite galaxies ubiquitous?

    NASA Astrophysics Data System (ADS)

    Phillips, John I.; Cooper, Michael C.; Bullock, James S.; Boylan-Kolchin, Michael

    2015-11-01

    We compare the dynamics of satellite galaxies in the Sloan Digital Sky Survey to simple models in order to test the hypothesis that a large fraction of satellites corotate in coherent planes. We confirm the previously reported excess of corotating satellite pairs located near diametric opposition with respect to their host, but show that this signal is unlikely to be due to rotating discs (or planes) of satellites. In particular, no overabundance of corotating satellites pairs is observed within ˜20°-50° of direct opposition, as would be expected for planar distributions inclined relative to the line of sight. Instead, the excess corotation for satellite pairs within ˜10° of opposition is consistent with random noise associated with undersampling of an underlying isotropic velocity distribution. Based upon the observed dynamics of the luminous satellite population, we conclude that at most 10 per cent of isolated hosts harbour corotating satellite planes (as traced by bright satellites).

  1. Advanced Communications Technology Satellite (ACTS)

    NASA Technical Reports Server (NTRS)

    Plecity, Mark S.; Nall, Mark E.

    1991-01-01

    The NASA Advanced Communications Technology Satellite (ACTS) provides high risk technologies having the potential to dramatically enhance the capabilities of the satellite communications industry. This experimental satellite, which will be launched by NASA in 1993, will furnish the technology necessary for providing a range of services. Utilizing the ACTS very-high-gain-hopping spot-beam antennas with on-board routing and processing, Very Small Aperture Terminal (VSAT) digital networks which provide on-demand, full-mesh-convectivity 1.544-MBPS services with only a single hop can be established. The high-gain spot-beam antenna at Ka-band permits wide area, flexible networks providing high data rate services between modest-size earth terminals.

  2. Schuler Period in LEO Satellites

    NASA Technical Reports Server (NTRS)

    Carpenter, Russell J.; Bar-Itzhack, Itzhack Y.

    2004-01-01

    This paper generalizes and extends the concept of the Schuler oscillation that occurs in the theory of inertial navigation systems, allowing one to see how the Schuler phenomenon affects inertial navigation systems operating in space. We show why a low earth orbit satellite's orbital period is identical to the period of the Schuler pendulum, which is the period of the errors for terrestrial inertial navigation systems. We also show that the generalized form of the Schuler oscillation takes the same form as the Hill-Clohessy-Wiltshire equations for satellite relative motion and that the period of the out-of-plane motion in neighboring satellite relative trajectories is the same as the Schuler period. Finally, we describe how INS gyro drift manifests itself in different coordinate systems for the orbital case. These results may assist orbital flight dynamics and attitude control systems engineers in the design and analysis of INS-equipped spacecraft

  3. General relativity and satellite orbits

    NASA Technical Reports Server (NTRS)

    Rubincam, D. P.

    1975-01-01

    The general relativistic correction to the position of a satellite is found by retaining Newtonian physics for an observer on the satellite and introducing a potential. The potential is expanded in terms of the Keplerian elements of the orbit and substituted in Lagrange's equations. Integration of the equations shows that a typical earth satellite with small orbital eccentricity is displaced by about 17 cm. from its unperturbed position after a single orbit, while the periodic displacement over the orbit reaches a maximum of about 3 cm. The moon is displaced by about the same amounts. Application of the equations to Mercury gives a total displacement of about 58 km. after one orbit and a maximum periodic displacement of about 12 km.

  4. Satellite Communications Using Commercial Protocols

    NASA Technical Reports Server (NTRS)

    Ivancic, William D.; Griner, James H.; Dimond, Robert; Frantz, Brian D.; Kachmar, Brian; Shell, Dan

    2000-01-01

    NASA Glenn Research Center has been working with industry, academia, and other government agencies in assessing commercial communications protocols for satellite and space-based applications. In addition, NASA Glenn has been developing and advocating new satellite-friendly modifications to existing communications protocol standards. This paper summarizes recent research into the applicability of various commercial standard protocols for use over satellite and space- based communications networks as well as expectations for future protocol development. It serves as a reference point from which the detailed work can be readily accessed. Areas that will be addressed include asynchronous-transfer-mode quality of service; completed and ongoing work of the Internet Engineering Task Force; data-link-layer protocol development for unidirectional link routing; and protocols for aeronautical applications, including mobile Internet protocol routing for wireless/mobile hosts and the aeronautical telecommunications network protocol.

  5. The Mexican national satellite system

    NASA Astrophysics Data System (ADS)

    Sanchez Ruiz, M. E.; Briskman, R. D.

    1983-10-01

    The satellites, tracking, telemetry, command, and monitoring facilities, and the earth station complex for the Mexican national satellite system, Morelos, are described. The spacecraft are intended to provide educational television, rural telephony, data transmission, and business and industrial services. Scheduled for 1985 launch, the satellites will be placed in GEO and use the C and Ku bands with 12 narrow band and six wideband transponders. Spin-stabilized and solar cell powered, the functional mass will be 666 kg, including propellant. The solar panels will provide 940 W of power and 830 W will be available from NiCd batteries during eclipse conditions. The earth station will be located at Iztapalapa, which will have a 12 m antenna, redundant uplink and downlink radios, and command and ranging equipment. Back-up capability will be provided by a station at Tulancingo. Ku band and C band stations are in planning.

  6. Gaussian entanglement distribution via satellite

    NASA Astrophysics Data System (ADS)

    Hosseinidehaj, Nedasadat; Malaney, Robert

    2015-02-01

    In this work we analyze three quantum communication schemes for the generation of Gaussian entanglement between two ground stations. Communication occurs via a satellite over two independent atmospheric fading channels dominated by turbulence-induced beam wander. In our first scheme, the engineering complexity remains largely on the ground transceivers, with the satellite acting simply as a reflector. Although the channel state information of the two atmospheric channels remains unknown in this scheme, the Gaussian entanglement generation between the ground stations can still be determined. On the ground, distillation and Gaussification procedures can be applied, leading to a refined Gaussian entanglement generation rate between the ground stations. We compare the rates produced by this first scheme with two competing schemes in which quantum complexity is added to the satellite, thereby illustrating the tradeoff between space-based engineering complexity and the rate of ground-station entanglement generation.

  7. Standard satellite data bus initiative

    NASA Astrophysics Data System (ADS)

    Spinney, Timothy; Yousef, Hassan

    The USAF Space Technology Center manages programs to reduce satellite costs through the appropriate use of microelectronics standardization. Ongoing programs such as the Standard Spacecraft Memory Module and Generic VHSIC Spaceborne Computer have provided an insight into the value of standardization and led to an initiative to coordinate microelectronics development around a standard satellite data bus, which should reduce costs by eliminating program- and contractor-unique interfaces, increasing production runs, and developing generic test equipment. Current efforts focus on the satellite housekeeping functions, and it is expected that the mission payload would also use this data bus. Based on existing housekeeping data-traffic requirements, several candidates have been identified for the standard data bus. The two candidates selected for further work are the ANSI X3T9.5 data bus and the linear token-passing data bus being proposed as part of the Advanced Tactical Fighter effort.

  8. Landsat—Earth observation satellites

    USGS Publications Warehouse

    ,

    2015-11-25

    Since 1972, Landsat satellites have continuously acquired space-based images of the Earth’s land surface, providing data that serve as valuable resources for land use/land change research. The data are useful to a number of applications including forestry, agriculture, geology, regional planning, and education. Landsat is a joint effort of the U.S. Geological Survey (USGS) and the National Aeronautics and Space Administration (NASA). NASA develops remote sensing instruments and the spacecraft, then launches and validates the performance of the instruments and satellites. The USGS then assumes ownership and operation of the satellites, in addition to managing all ground reception, data archiving, product generation, and data distribution. The result of this program is an unprecedented continuing record of natural and human-induced changes on the global landscape.

  9. Interference problems for nongeostationary satellites

    NASA Technical Reports Server (NTRS)

    Sollfrey, W.

    1984-01-01

    The interference problems faced by nongeostationary satellites may be of major significance. A general discussion indicates the scope of the problems and describes several configurations of importance. Computer programs are described, which are employed by NASA/JPL and the U.S. Air Force Satellite Control Facility to provide interference-free scheduling of commands and data transmission. Satellite system mission planners are not concerned with the precise prediction of interference episodes, but rather with the expected total amount of interference, the mean and maximum duration of events, and the mean spacing between episodes. The procedures in the theory of probability developed by the author which permit calculation of such quantities are described and applied to several real cases. It may be anticipated that the problems will become steadily worse in the future as more and more data transmissions attempt to occupy the same frequency band.

  10. THE MASSIVE SATELLITE POPULATION OF MILKY-WAY-SIZED GALAXIES

    SciTech Connect

    Rodriguez-Puebla, Aldo; Avila-Reese, Vladimir; Drory, Niv

    2013-08-20

    Several occupational distributions for satellite galaxies more massive than m{sub *} Almost-Equal-To 4 Multiplication-Sign 10{sup 7} M{sub Sun} around Milky-Way (MW)-sized hosts are presented and used to predict the internal dynamics of these satellites as a function of m{sub *}. For the analysis, a large galaxy group mock catalog is constructed on the basis of (sub)halo-to-stellar mass relations fully constrained with currently available observations, namely the galaxy stellar mass function decomposed into centrals and satellites, and the two-point correlation functions at different masses. We find that 6.6% of MW-sized galaxies host two satellites in the mass range of the Small and Large Magellanic Clouds (SMC and LMC, respectively). The probabilities of the MW-sized galaxies having one satellite equal to or larger than the LMC, two satellites equal to or larger than the SMC, or three satellites equal to or larger than Sagittarius (Sgr) are Almost-Equal-To 0.26, 0.14, and 0.14, respectively. The cumulative satellite mass function of the MW, N{sub s} ({>=}m{sub *}) , down to the mass of the Fornax dwarf is within the 1{sigma} distribution of all the MW-sized galaxies. We find that MW-sized hosts with three satellites more massive than Sgr (as the MW) are among the most common cases. However, the most and second most massive satellites in these systems are smaller than the LMC and SMC by roughly 0.7 and 0.8 dex, respectively. We conclude that the distribution N{sub s} ({>=}m{sub *}) for MW-sized galaxies is quite broad, the particular case of the MW being of low frequency but not an outlier. The halo mass of MW-sized galaxies correlates only weakly with N{sub s} ({>=}m{sub *}). Then, it is not possible to accurately determine the MW halo mass by means of its N{sub s} ({>=}m{sub *}); from our catalog, we constrain a lower limit of 1.38 Multiplication-Sign 10{sup 12} M{sub Sun} at the 1{sigma} level. Our analysis strongly suggests that the abundance of massive

  11. Working group for planetary system nomenclature

    NASA Technical Reports Server (NTRS)

    1993-01-01

    Most of the activity of the Working Group and Task Group of the IAU during these three years has been centered on the nomenclature of Neptune's satellites and rings as revealed by the Voyager spacecraft. The emphasis is now shifting to Venus, in preparation for the detailed radar mapping of that planet begun by the Magellan spacecraft in August 1990. Approval has been asked for nomenclature of the Earth's moon, Venus, Mars, and Triton features as well as 4 other Neptune satellites and three Neptune rings.

  12. Group Grammar

    ERIC Educational Resources Information Center

    Adams, Karen

    2015-01-01

    In this article Karen Adams demonstrates how to incorporate group grammar techniques into a classroom activity. In the activity, students practice using the target grammar to do something they naturally enjoy: learning about each other.

  13. Satellite-Based Quantum Communications

    SciTech Connect

    Hughes, Richard J; Nordholt, Jane E; McCabe, Kevin P; Newell, Raymond T; Peterson, Charles G

    2010-09-20

    Single-photon quantum communications (QC) offers the attractive feature of 'future proof', forward security rooted in the laws of quantum physics. Ground based quantum key distribution (QKD) experiments in optical fiber have attained transmission ranges in excess of 200km, but for larger distances we proposed a methodology for satellite-based QC. Over the past decade we have devised solutions to the technical challenges to satellite-to-ground QC, and we now have a clear concept for how space-based QC could be performed and potentially utilized within a trusted QKD network architecture. Functioning as a trusted QKD node, a QC satellite ('QC-sat') could deliver secret keys to the key stores of ground-based trusted QKD network nodes, to each of which multiple users are connected by optical fiber or free-space QC. A QC-sat could thereby extend quantum-secured connectivity to geographically disjoint domains, separated by continental or inter-continental distances. In this paper we describe our system concept that makes QC feasible with low-earth orbit (LEO) QC-sats (200-km-2,000-km altitude orbits), and the results of link modeling of expected performance. Using the architecture that we have developed, LEO satellite-to-ground QKD will be feasible with secret bit yields of several hundred 256-bit AES keys per contact. With multiple ground sites separated by {approx} 100km, mitigation of cloudiness over any single ground site would be possible, potentially allowing multiple contact opportunities each day. The essential next step is an experimental QC-sat. A number of LEO-platforms would be suitable, ranging from a dedicated, three-axis stabilized small satellite, to a secondary experiment on an imaging satellite. to the ISS. With one or more QC-sats, low-latency quantum-secured communications could then be provided to ground-based users on a global scale. Air-to-ground QC would also be possible.

  14. Reinventing the Solar Power Satellite

    NASA Technical Reports Server (NTRS)

    Landis, Geoffrey A.

    2004-01-01

    The selling price of electrical power varies with time. The economic viability of space solar power is maximum if the power can be sold at peak power rates, instead of baseline rate. Price and demand of electricity was examined from spot-market data from four example markets: New England, New York City, suburban New York, and California. The data was averaged to show the average price and demand for power as a function of time of day and time of year. Demand varies roughly by a factor of two between the early-morning minimum demand, and the afternoon maximum; both the amount of peak power, and the location of the peak, depends significantly on the location and the weather. The demand curves were compared to the availability curves for solar energy and for tracking and non-tracking satellite solar power systems in order to compare the market value of terrestrial and solar electrical power. In part 2, new designs for a space solar power (SSP) system were analyzed to provide electrical power to Earth for economically competitive rates. The approach was to look at innovative power architectures to more practical approaches to space solar power. A significant barrier is the initial investment required before the first power is returned. Three new concepts for solar power satellites were invented and analyzed: a solar power satellite in the Earth-Sun L2 point, a geosynchronous no-moving parts solar power satellite, and a nontracking geosynchronous solar power satellite with integral phased array. The integral-array satellite had several advantages, including an initial investment cost approximately eight times lower than the conventional design.

  15. Multipurpose Communication Satellite solar array

    NASA Astrophysics Data System (ADS)

    Bastard, J. L.; Guyot, Ph.

    Through research and development studies, Aerospatiale has developed with the French National Space Agency (CNES) a new concept of a rigid Solar Array (GSR) which covers a range of power between 1 kW and 10 kW EOL 7 yr. This technology is used by Aerospatiale on the currently running programs:—TELECOM 1, Telecommunication satellite, spinned in transfer; —ARABSAT, Telecommunication satellite, 3-axis stabilized in transfer; —TELE-X and TV-SAT/TDF1, Direct Broadcasting satellites, 3-axis stabilized in transfer. This paper deals with the description and the electrical and mechanical performance of the Multipurpose Communication Satellite Solar Array (M.C.S.). For this satellite, which is expected to be launched in 1984, Aerospatiale has selected the following concept: primary power (1.4 kW EOL 7 yr) will be provided by two separate sun-oriented solar array wings equipped with AEG Telefunken BSR (Back Surface Reflector) solar cells. This solar generator is directly derived from the GSR technology. Owing to the three-axis stabilization of the satellite and the partial deployment of the solar array during the transfer phase it has been necessary to use a primary and a secondary hold-down devices. In the same way the position of the shunt on the solar generator induced an increase of the mass, because of the supplementary hold-down point and of the support structure. Now scribing Laser System leads to the optimization of the solar cells dimensions and allows a better fill factor of the panels and so an increase of the power performance. Beside the M.C.S concept which is fully adapted as regards its mission specifications, it was interesting to present different concepts of solar generators optimized not only as regards mass budget but also power budget. These concepts covering a large range of powers are fully adapted to telecommunication missions.

  16. Natural Satellite Ephemerides at JPL

    NASA Astrophysics Data System (ADS)

    Jacobson, Robert Arthur; Brozovic, Marina

    2015-08-01

    There are currently 176 known natural planetary satellites in the solar system; 150 are officially recognized by the IAU and 26 have IAU provisional designations. We maintain ephemerides for all of the satellites at NASA's Jet Propulsion Laboratory (JPL) and make them available electronically through the On-Line Solar System Data Service known as Horizons(http://ssd.jpl.nasa.gov/horizons) and in the form of generic Spice Kernels (SPK files) from NASA's Navigation and Ancillary Information Facility (http://naif.jpl.nasa.gov/naif). General satellite information such as physical constants and descriptive orbital elements can be found on the JPL Solar System Dynamics Website (http://ssd.jpl.nasa.gov). JPL's ephemerides directly support planetary spacecraft missions both in navigation and science data analysis. They are also used in general scientific investigations of planetary systems. We produce the ephemerides by fitting numerically integrated orbits to observational data. Our model for the satellite dynamics accounts for the gravitational interactions within a planetary system and the external gravitational perturbations from the Sun and planets. We rely on an extensive data set to determine the parameters in our dynamical models. The majority of the observations are visual, photographic, and CCD astrometry acquired from Earthbased observatories worldwide and the Hubble Space Telescope. Additional observations include optical and photoelectric transits, eclipses, occultations, Earthbased radar ranging, spacecraft imaging,and spacecraft radiometric tracking. The latter data provide information on the planet and satellite gravity fields as well as the satellite position at the times of spacecraft close encounters. In this paper we report on the status of the ephemerides and our plan for future development, specifically that in support of NASA's Juno, Cassini, and New Horizons missions to Jupiter, Saturn, and Pluto, respectively.

  17. Close Pairings of Galilean Satellites Observed Using Speckle Interferometry

    NASA Astrophysics Data System (ADS)

    Mason, B. D.; Kaplan, G. H.; Douglass, G. G.; Pascu, D.; Aksnes, K.

    1999-09-01

    During November-December 1998, a series of events occurred involving the Galilean satellites of Jupiter, where two satellites (usually Io and Europa, but sometimes Europa and Ganymede) passed within 5 arcsec of each other. Depending on the orbital geometry and closest separation (as close as 2.9 arcsec) the events lasted anywhere from 20 minutes to several hours. Since 5 arcsec roughly defines the atmospheric isoplanatic patch, attempts were made to observe these events using the speckle interferometry camera attached to the U.S. Naval Observatory (USNO) 26-inch refractor. The camera and associated software are normally used for precise measurements of the distance and position angle of binary star components. For the satellite events, the goal was to obtain very precise relative positions of the satellite pairs at specific times, as well as the time of apparent closest separation. Speckle observations of binary stars made from USNO typically yield positional accuracy of about 1 We successfully observed 4 out of a possible 8 events visible from USNO. Reduction of these observations is in progress. Despite the fact that the Galileans are resolved, not point sources, autocorrelations of the speckle patterns appear fairly strong. However, because of the relative motion of the satellites, only short integration times can be used, and it remains to be seen whether the signal-to-noise ratio will permit relative position measurements of useful precision. Close pairings of the Galilean satellites occur in series that are determined by the mutual resonances, within a geometric envelope defined by the apparent inclination of the orbital planes (i.e., Jupiter's equator) and distance. There is another series of events in May-June 1999, then again in January 2000. This technique may also be applicable to some of the Saturnian satellites near the time of ring-plane crossing. We invite other speckle interferometry groups to attempt observations of these events so that the

  18. Advances Made in the Next Generation of Satellite Networks

    NASA Technical Reports Server (NTRS)

    Bhasin, Kul B.

    1999-01-01

    Because of the unique networking characteristics of communications satellites, global satellite networks are moving to the forefront in enhancing national and global information infrastructures. Simultaneously, broadband data services, which are emerging as the major market driver for future satellite and terrestrial networks, are being widely acknowledged as the foundation for an efficient global information infrastructure. In the past 2 years, various task forces and working groups around the globe have identified pivotal topics and key issues to address if we are to realize such networks in a timely fashion. In response, industry, government, and academia undertook efforts to address these topics and issues. A workshop was organized to provide a forum to assess the current state-of-the-art, identify key issues, and highlight the emerging trends in the next-generation architectures, data protocol development, communication interoperability, and applications. The Satellite Networks: Architectures, Applications, and Technologies Workshop was hosted by the Space Communication Program at the NASA Lewis Research Center in Cleveland, Ohio. Nearly 300 executives and technical experts from academia, industry, and government, representing the United States and eight other countries, attended the event (June 2 to 4, 1998). The program included seven panels and invited sessions and nine breakout sessions in which 42 speakers presented on technical topics. The proceedings covers a wide range of topics: access technology and protocols, architectures and network simulations, asynchronous transfer mode (ATM) over satellite networks, Internet over satellite networks, interoperability experiments and applications, multicasting, NASA interoperability experiment programs, NASA mission applications, and Transmission Control Protocol/Internet Protocol (TCP/IP) over satellite: issues, relevance, and experience.

  19. Satellites for U.S. education - Needs, opportunities and systems.

    NASA Technical Reports Server (NTRS)

    Morgan, R. P.; Singh, J. P.; Anderson, B. D.; Greenberg, E.

    1972-01-01

    This paper presents results of a continuing interdisciplinary study of the potential applications of Fixed- and Broadcast-Satellites for educational information transfer in the United States for the period 1975-1985. The status of U.S. education is examined and needs, trends and issues are discussed. The existing educational telecommunications infrastructure is examined and opportunities for satellite services are defined. Potential uses include networking of educational institutions and service centers for delivery of public and instructional television, computer-aided instruction, computing and information resources to regions and groups not now adequately served. Systems alternatives and some of the organizational and economic issues inherent in the deployment of an educational satellite system are discussed.-

  20. Mission and sampling analyses for atmospheric satellite experiments

    NASA Technical Reports Server (NTRS)

    Harrison, Edwin F.

    1990-01-01

    Orbital analyses, instrument-viewing geometry studies, and sampling simulations are performed to define mission concepts for advanced atmospheric research satellite experiments. These analyses are conducted in collaboration with NASA Headquarters and working groups consisting of atmospheric scientists and experiment developers. Analytical techniques are developed and used to optimize geographical coverage, sensor-viewing geometries, data gathering strategies, sampling schemes, orbital characteristics, satellite launch times, and operational modes of the various experiments and mission concepts. Short-term (7 day) Shuttle Missions, the Upper Atmosphere Research Satellite (UARS), and multisatellite missions such as the Earth Observing System (EOS) are being studied. Atmospheric experiments which are being analyzed include nadir-viewing sounders, limb-emission scanners, laser systems, and solar-occultation techniques.

  1. INMARSAT - The International Maritime Satellite Organization: Origins and structure

    NASA Technical Reports Server (NTRS)

    Doyle, S. E.

    1977-01-01

    The third session of the International Conference on the Establishment of an International Maritime Satellite System established the International Maritime Satellite Organization (INMARSAT) in 1976. Its main functions are to improve maritime communications via satellite, thereby facilitating more efficient emergency communications, ship management, and maritime public correspondence services. INMARSAT's aims are similar to those of the Intergovernmental Maritime Consultative Organization (IMCO), the main United Nations organization dealing with maritime affairs. The specific functions of INMARSAT have been established by an Intersessional Working Group (IWG) which met three times between general conference meetings. Initial investment shares for the creation of INMARSAT were shared by the United States (17%), the United Kingdom (12%), the U.S.S.R. (11%), Norway (9.50%), Japan (8.45%), Italy (4.37%), and France (3.50%).

  2. Launch vehicles for communications satellites

    NASA Technical Reports Server (NTRS)

    Mahon, J. B.

    1982-01-01

    After giving brief development histories of the Delta and the Atlas Centaur launch vehicles, attention is given to the operational characteristics of the ascent, parking orbit, transfer orbit, and orbital insertion phases of the delivery of a communications satellite to a geostationary orbit by means of a Delta launch vehicle. NASA plans to employ Delta vehicles for as long as they are needed during the transition period to the Space Shuttle. NASA planning for Atlas Centaur includes launches through 1985 for INTELSAT-VA, and through 1986 for FLTSATCOM satellites.

  3. Data compression for satellite images

    NASA Technical Reports Server (NTRS)

    Chen, P. H.; Wintz, P. A.

    1976-01-01

    An efficient data compression system is presented for satellite pictures and two grey level pictures derived from satellite pictures. The compression techniques take advantages of the correlation between adjacent picture elements. Several source coding methods are investigated. Double delta coding is presented and shown to be the most efficient. Both predictive differential quantizing technique and double delta coding can be significantly improved by applying a background skipping technique. An extension code is constructed. This code requires very little storage space and operates efficiently. Simulation results are presented for various coding schemes and source codes.

  4. Environmentally induced discharges on satellites

    NASA Technical Reports Server (NTRS)

    Stevens, N. J.

    1982-01-01

    The problem of assessing hazards to geosynchronous satellite systems from geomagnetic substorm encounters is investigated. The available space flight data, coupled with analytical modeling studies, show that only relatively low differential charging is possible from environmental encounters. Using an analytical study of a discharge event on SCATHA, a discharge process is postulated where a small amount of charge is lost to space. These characteristics could then be used as inputs to a coupling model to determine the hazard to a spacecraft. The procedure is applied to a three axis stabilized satellite design.

  5. Customer concerns regarding satellite servicing

    NASA Technical Reports Server (NTRS)

    Rysavy, Gordon

    1987-01-01

    The organization of orbital servicing of satellites is discussed. Provision of servicing equipment; design interfaces between the satellite and the servicing equipment; and the economic viability of the concept are discussed. The proposed solution for satisfying customer concerns is for the servicing organizations to baseline an adequate inventory of servicing equipment with standard interfaces and established servicing costs. With this knowledge, the customer can conduct tradeoff studies and make programmatic decisions regarding servicing options. A dialog procedure between customers and servicing specialists is outlined.

  6. Satellite imagery of the earth

    USGS Publications Warehouse

    Merifield, P.M.; Cronin, J.; Foshee, L.L.; Gawarecki, S.J.; Neal, J.T.; Stevenson, R.E.; Stone, R.O.; Williams, R.S., Jr.

    1969-01-01

    Photography of the Earth from spacecraft has application to both atmospheric and Earth sciences. Gemini and Apollo photographs have furnished information on sea surface roughness, areas of potential upwelling and oceanic current systems. Regional geologic structures and geomorphologic features are also recorded in orbital photographs. Infrared satellite imagery provides meteorological and hydrological data and is potentially useful for locating fresh water springs along coastal areas, sources of geothermal power and volcanic activity. Ground and airborne surveys are being undertaken to create a basis for the interpretation of data obtained from future satellite systems.

  7. NASA's mobile satellite development program

    NASA Technical Reports Server (NTRS)

    Rafferty, William; Dessouky, Khaled; Sue, Miles

    1988-01-01

    A Mobile Satellite System (MSS) will provide data and voice communications over a vast geographical area to a large population of mobile users. A technical overview is given of the extensive research and development studies and development performed under NASA's mobile satellite program (MSAT-X) in support of the introduction of a U.S. MSS. The critical technologies necessary to enable such a system are emphasized: vehicle antennas, modulation and coding, speech coders, networking and propagation characterization. Also proposed is a first, and future generation MSS architecture based upon realized ground segment equipment and advanced space segment studies.

  8. Mobile satellite communications for consumers

    NASA Astrophysics Data System (ADS)

    Noreen, Gary K.

    1991-11-01

    The RadioSat system based on MSAT satellites and scheduled for launch in 1994 is described. The RadioSat system will provide integrated communications and navigation services to consumers, including nationwide digital audio broadcasts, data broadcasts, precision navigation, and two-way voice and data communications. Particular attention is given to the MSAT satellite system capabilities and economics. It is concluded that the RadioSat system will be capable of providing a low-cost, highly flexible two-way communications for consumers that can be adapted to various applications.

  9. Land mobile satellite propagation results

    NASA Technical Reports Server (NTRS)

    Nicholas, David C.

    1988-01-01

    During the Fall of 1987 a land mobile satellite demonstration using the MARECS B2 satellite at 26 degrees W was performed. While all the data have not been digested, some observations are in order. First, the system worked remarkably well for the margins indicated. Second, when the system worked poorly, the experimenters could almost always identify terrain or other obstacles causing blockage. Third, the forward link seems relatively more reliable than the return link, and occasional return link problems occured which have not been entirely explained.

  10. Chameleon gravity and satellite geodesy

    NASA Astrophysics Data System (ADS)

    Morris, J. R.

    2014-12-01

    We consider the possibility of the detection of a chameleon effect by an earth orbiting satellite such as LAGEOS, and possible constraints that might be placed on chameleon model parameters. Approximate constraints presented here result from using a simple monopole approximation for the gravitational field of the earth, along with results from the Khoury-Weltman chameleon model, solar system constraints obtained from the Cassini mission, and parameter bounds obtained from the LAGEOS satellite. It is furthermore suggested that a comparison of ground-based and space-based multipole moments of the geopotential could reveal a possible chameleon effect.

  11. Severe storms observing satellite (STORMSAT)

    NASA Technical Reports Server (NTRS)

    1976-01-01

    The primary payload for this satellite is the Advanced Atmospheric Sounding and Imaging Radiometer which will perform precise infrared temperature sounding and visible/infrared imaging from geostationary orbit. A secondary payload instrument which may be utilized on STORMSAT is the Microwave Atmospheric Sounding Radiometer which provides an independent set of temperature and humidity sounding in cloudy, meteorologically active regions. The study provides satellite designs and identifies mission-unique subsystems using the Multimission Modular Spacecraft using a Shuttle/Interim Upper Stage launch vehicle.

  12. Trends in NASA communication satellites

    NASA Technical Reports Server (NTRS)

    Sivo, J. N.; Robbins, W. H.; Stretchberry, D. M.

    1972-01-01

    Satellite telecommunications can help to satisfy several national needs such as education, health care, cultural opportunities, and data transfer. There are current experiments being conducted with NASA spacecraft ATS 1, 3, and 5 in an attempt to satisfy these national needs. Future experiments are planned for the ATS F/G and CTS spacecrafts. The next generation of communications satellites must provide multiple region coverage, multichannel capability, high quality TV pictures, and must allow low cost ground receivers to be used. The proposed NASA spacecrafts, ATS H/I, will satisfy these requirements. Other countries of the world can benefit from ATS H/I technology.

  13. Satellite switched FDMA advanced communication technology satellite program

    NASA Technical Reports Server (NTRS)

    Atwood, S.; Higton, G. H.; Wood, K.; Kline, A.; Furiga, A.; Rausch, M.; Jan, Y.

    1982-01-01

    The satellite switched frequency division multiple access system provided a detailed system architecture that supports a point to point communication system for long haul voice, video and data traffic between small Earth terminals at Ka band frequencies at 30/20 GHz. A detailed system design is presented for the space segment, small terminal/trunking segment at network control segment for domestic traffic model A or B, each totaling 3.8 Gb/s of small terminal traffic and 6.2 Gb/s trunk traffic. The small terminal traffic (3.8 Gb/s) is emphasized, for the satellite router portion of the system design, which is a composite of thousands of Earth stations with digital traffic ranging from a single 32 Kb/s CVSD voice channel to thousands of channels containing voice, video and data with a data rate as high as 33 Mb/s. The system design concept presented, effectively optimizes a unique frequency and channelization plan for both traffic models A and B with minimum reorganization of the satellite payload transponder subsystem hardware design. The unique zoning concept allows multiple beam antennas while maximizing multiple carrier frequency reuse. Detailed hardware design estimates for an FDMA router (part of the satellite transponder subsystem) indicate a weight and dc power budget of 353 lbs, 195 watts for traffic model A and 498 lbs, 244 watts for traffic model B.

  14. Systemic transplantation of human umbilical cord derived mesenchymal stem cells-educated T regulatory cells improved the impaired cognition in AβPPswe/PS1dE9 transgenic mice.

    PubMed

    Yang, Hongna; Yang, Hui; Xie, Zhaohong; Wei, Lifei; Bi, Jianzhong

    2013-01-01

    Alzheimer's disease (AD) is one of most prevalent dementias, which is characterized by the deposition of extracellular amyloid-beta protein (Aβ) and the formation of neurofibrillary tangles within neurons. Although stereotaxic transplantation of mesenchymal stem cells (MSCs) into the hippocampus of AD animal model as immunomodulatory cells has been suggested as a potential therapeutic approach to prevent the progress of AD, it is invasive and difficult for clinical perform. Systemic and central nervous system inflammation play an important role in pathogenesis of AD. T regulatory cells (Tregs) play a crucial role in maintaining systemic immune homeostasis, indicating that transplantation of Tregs could prevent the progress of the inflammation. In this study, we aimed to evaluate whether systemic transplantation of purified autologous Tregs from spleens of AβPPswe/PS1dE9 double-transgenic mice after MSCs from human umbilical cords (UC-MSCs) education in vitro for 3 days could improve the neuropathology and cognition deficits in AβPPswe/PS1dE9 double-transgenic mice. We observed that systemic transplantation of autologous Tregs significantly ameliorate the impaired cognition and reduced the Aβ plaque deposition and the levels of soluble Aβ, accompanied with significantly decreased levels of activated microglia and systemic inflammatory factors. In conclusion, systemic transplantation of autologous Tregs may be an effective and safe intervention to prevent the progress of AD.

  15. NASA SSTI CLARK 3-meter imaging satellite

    NASA Technical Reports Server (NTRS)

    Sebestyen, George; Hayduk, Robert J.

    1996-01-01

    Within the framework of NASA's Small Satellite Technology Initiative (SSTI) CLARK program, the development of a high technology small satellite is reported on. The satellite will provide 3 m resolution panchromatic and 15 m resolution multispectral image capabilities. The satellite, programmed for launch in 1996, will be in a sun-synchronous orbit and includes the following systems: three-axis zero momentum attitude control; hydrazine propulsion for stationkeeping; Global Positioning System satellite position and star tracker attitude determination; and onboard image storage capability. The objectives of the SSTI CLARK program, the technical characteristics of the satellite, the techniques employed to reduce costs, and the image processing, archiving and distribution are described.

  16. Broadcast satellite service: The international dimension

    NASA Technical Reports Server (NTRS)

    Samara, Noah

    1991-01-01

    The dawn of the 1990's has witnessed the birth of a new satellite service - satellite sound broadcasting. This new service is characterized by digital transmission at data rates up to 256 kb/s from satellites in geostationary orbit to small, low-cost, mobile and portable receivers. The satellite sound broadcasting service is a logical step beyond navigation satellite service, such as that provided by the GPS Navstar system. The mass market appeal of satellite sound broadcasting in the area of lightsat technology and low-cost digital radios has greatly facilitated the financing of this type of space service.

  17. Physical properties of the Uranian satellites

    NASA Technical Reports Server (NTRS)

    Brown, Robert H.; Johnson, Torrence V.; Synnott, Stephen; Anderson, John D.; Jacobson, Robert A.; Dermott, Stanley F.; Thomas, Peter C.

    1991-01-01

    Data regarding the Uranian satellites' radii, masses, mean density, and, consequently, their internal structures obtained from the Voyager encounter are analyzed. Topics covered are the sizes, shapes, topography, masses, densities, and models of the internal structures of the five major satellites. The sizes and shapes of the 10 small satellites discovered by Voyager 2 are discussed. The physical properties of the large satellites of Uranus are compared to those other satellites in the outer solar system, particularly those of Jupiter and Saturn, and the implications that these comparisons have for understanding the origin and evolution of the satellites of Uranus are discussed.

  18. The icy Jovian satellites after the Galileo mission

    NASA Astrophysics Data System (ADS)

    Greenberg, Richard

    2010-03-01

    The icy satellites of Jupiter, Callisto, Ganymede, Europa and Amalthea have diverse and remarkable characteristics. Their initial compositions were determined by conditions in the circum-Jovian nebula, just as the planets' initial properties were governed by their formation within the circumsolar nebula. The satellites subsequently evolved under the complex interplay of orbital and geophysical processes, especially the effects of orbital resonances, tides, internal differentiation and heat. The history and character of the satellites can be inferred from consideration of the formation of planets and the satellites, from studies of their plausible orbital evolution, from measurements of geophysical properties, especially gravitational and magnetic fields, from observations of the compositions and geological structure of their surfaces and from theoretical modeling of the processes that connect these lines of evidence. The three large icy satellites probably contain significant liquid water: Europa has a deep liquid water ocean under a thin surface layer of ice; Ganymede and Callisto likely have relatively thin liquid water layers deep below their surfaces. Models of formation are challenged by the surprising properties of the outermost and innermost of the group: Callisto is partially differentiated, with rock and ice mixed through much of its interior; and tiny Amalthea also appears to be largely composed of ice. Each of the four moons is fascinating in its own right, and the ensemble provides a powerful set of constraints on the processes that led to their formation and evolution.

  19. Boeing Satellite Television Airplane Receiving System (STARS) performance

    NASA Technical Reports Server (NTRS)

    Vertatschitsch, Edward J.; Fitzsimmons, George W.

    1995-01-01

    Boeing Defense and Space Group is developing a Satellite Television Airplane Receiving System (STARS) capable of delivering Direct Broadcast Satellite (DBS) television to an aircraft in-flight. This enables a new service for commercial airplanes that will make use of existing and future DBS systems. The home entertainment satellites, along with STARS, provide a new mobile satellite communication application. This paper will provide a brief background of the antenna issues associated with STARS for commercial airplanes and then describe the innovative Boeing phased-array solution to these problems. The paper then provides a link budget of the STARS using the Hughes DBS as an example, but the system will work with all of the proposed DBS satellites in the 12.2-12.7 GHz band. It concludes with operational performance calculations of the STARS system, supported by measured test data of an operational 16-element subarray. Although this system is being developed for commercial airplanes, it is well suited for a wide variety of mobile military and other commercial communications systems in air, on land and at sea. The applications include sending high quality video for the digital battlefield and large volumes of data on the information superhighway at rates in excess of 350 Mbps.

  20. Evidence for asymmetric inertial instability in the FIRE satellite dataset

    NASA Technical Reports Server (NTRS)

    Stevens, Duane E.; Ciesielski, Paul E.

    1990-01-01

    One of the main goals of the First ISCCP Regional Experiment (FIRE) is obtaining the basic knowledge to better interpret satellite image of clouds on regional and smaller scales. An analysis of a mesoscale circulation phenomenon as observed in hourly FIRE satellite images is presented. Specifically, the phenomenon of interest appeared on satellite images as a group of propagating cloud wavelets located on the edge of a cirrus canopy on the anticylonic side of a strong, upper-level subtropical jet. These wavelets, which were observed between 1300 and 2200 GMT on 25 February 1987, are seen most distinctly in the GOES-West infrared satellite picture at 1800 GMT. The purpose is to document that these wavelets were a manifestation of asymmetric inertial instability. During their lifetime, the wavelets were located over the North American synoptic sounding network, so that the meteorological conditions surrounding their occurrence could be examined. A particular emphasis of the analysis is on the jet streak in which the wavelets were imbedded. The characteristics of the wavelets are examined using hourly satellite imagery. The hypothesis that inertial instability is the dynamical mechanism responsible for generating the observed cloud wavelets was examined. To further substantiate this contention, the observed characteristics of the wavelets are compared to, and found to be consistent with, a theoretical model of inertia instability by Stevens and Ciesielski.

  1. Searching for satellites of Ceres

    NASA Astrophysics Data System (ADS)

    Schmidt, B.; Li, J.; McFadden, L.; Mutchler, M.; McLean, B.; Russell, C.

    2014-07-01

    The existence of satellites, or lack thereof, around Ceres is of great interest to the Dawn mission, which is currently en route to Ceres and will arrive in February 2015. The Dawn spacecraft will orbit Ceres at altitudes of 1180 to 6400 km, well within the satellite stability region. The final opportunity for observations of Ceres with HST prior to Dawn's arrival occurred in April 2014, when Ceres will make a close pass at opposition to Earth. In addition to providing additional targets for exciting physical studies by the Dawn instruments, satellites, if there were any, would substantially affect Dawn's orbit planning in order to accommodate observations and ensure spacecraft safety. For example, detection of satellites would allow this program to derive a more accurate measurement of the mass of Ceres, which is important for the mission planners to determine the orbit of the spacecraft. With the observation planning process already underway, early detection of satellites will provide sufficient time to adapt mission plans to be able to observe any satellites on ingress or during the mapping orbits. The timing is particularly important, since the spacecraft now has use of only two reaction wheels, which is already impacting mission design, and which prevents Dawn from conducting its own deep satellite search as was accomplished prior to arrival at Vesta. Because of this, an HST survey is critical for Dawn operations at Ceres. Since satellite detection could require a change to the mission's nominal orbital strategy and present risk from dust associated with any satellites, it is crucial to put Dawn in the best position to succeed. HST observed Ceres using the High Resolution Channel (HRC) of the Advanced Camera for Surveys (ACS) to study the physical properties of Ceres and carried out surface mapping (Parker et al. 2004, Thomas et al. 2005, Li et al. 2006). Several ''long-V'' (F555W filter) exposures were taken using the full field of view of the ACS-HRC to

  2. Searching for satellites of Ceres

    NASA Astrophysics Data System (ADS)

    Schmidt, B.; Li, J.; McFadden, L.; Mutchler, M.; McLean, B.; Russell, C.

    2014-07-01

    The existence of satellites, or lack thereof, around Ceres is of great interest to the Dawn mission, which is currently en route to Ceres and will arrive in February 2015. The Dawn spacecraft will orbit Ceres at altitudes of 1180 to 6400 km, well within the satellite stability region. The final opportunity for observations of Ceres with HST prior to Dawn's arrival occurred in April 2014, when Ceres will make a close pass at opposition to Earth. In addition to providing additional targets for exciting physical studies by the Dawn instruments, satellites, if there were any, would substantially affect Dawn's orbit planning in order to accommodate observations and ensure spacecraft safety. For example, detection of satellites would allow this program to derive a more accurate measurement of the mass of Ceres, which is important for the mission planners to determine the orbit of the spacecraft. With the observation planning process already underway, early detection of satellites will provide sufficient time to adapt mission plans to be able to observe any satellites on ingress or during the mapping orbits. The timing is particularly important, since the spacecraft now has use of only two reaction wheels, which is already impacting mission design, and which prevents Dawn from conducting its own deep satellite search as was accomplished prior to arrival at Vesta. Because of this, an HST survey is critical for Dawn operations at Ceres. Since satellite detection could require a change to the mission's nominal orbital strategy and present risk from dust associated with any satellites, it is crucial to put Dawn in the best position to succeed. HST observed Ceres using the High Resolution Channel (HRC) of the Advanced Camera for Surveys (ACS) to study the physical properties of Ceres and carried out surface mapping (Parker et al. 2004, Thomas et al. 2005, Li et al. 2006). Several ''long-V'' (F555W filter) exposures were taken using the full field of view of the ACS-HRC to

  3. Group dynamics.

    PubMed

    Scandiffio, A L

    1990-12-01

    Group dynamics play a significant role within any organization, culture, or unit. The important thing to remember with any of these structures is that they are made up of people--people with different ideas, motivations, background, and sometimes different agendas. Most groups, formal or informal, look for a leader in an effort to maintain cohesiveness of the unit. At times, that cultural bond must be developed; once developed, it must be nurtured. There are also times that one of the group no longer finds the culture comfortable and begins to act out behaviorally. It is these times that become trying for the leader as she or he attempts to remain objective when that which was once in the building phase of group cohesiveness starts to fall apart. At all times, the manager must continue to view the employee creating the disturbance as an integral part of the group. It is at this time that it is beneficial to perceive the employee exhibiting problem behaviors as a special employee, as one who needs the benefit of your experience and skills, as one who is still part of the group. It is also during this time that the manager should focus upon her or his own views in the area of power, communication, and the corporate culture of the unit that one has established before attempting to understand another's point of view. Once we understand our own motivation and accept ourselves, it is then that we may move on to offer assistance to another. Once we understand our insecurities recognizing staff dysfunction as a symptom of system dysfunction will not be so threatening to the concept of the manager that we perceive ourselves to be. It takes a secure person to admit that she or he favors staff before deciding to do something to change things. The important thing to know is that it can be done. The favored staff can find a new way of relating to others, the special employee can find new modes of behavior (and even find self-esteem in the process), the group can find new ways

  4. Mobile satellite regulation in the United States

    NASA Technical Reports Server (NTRS)

    Levin, Lon C.; Sonnenfeldt, Walter H.

    1990-01-01

    During the last decade, the U.S. FCC has developed the regulatory structure for the provision of mobile services via satellite. In May 1989, the FCC awarded American Mobile Satellite Corporation (AMSC) a license to provide the full range of domestic mobile satellite services in the U.S. At that time, the FCC reaffirmed the U.S. mobile satellite industry structure and spectrum allocations that had been adopted previously. Also in May 1989, the FCC authorized the Communications Satellite Corporation (COMSAT), the U.S. Signatory to Inmarsat, to provide international aeronautical satellite service via the Inmarsat system. Earlier in 1989, the FCC permitted the use of Ku-band satellites to provide messaging and tracking services. In the mid-1980's, the FCC established the Radiodetermination Satellite Service and awarded licenses. Among the mobile satellite matters currently facing the FCC are whether additional spectrum should be allocated for domestic 'generic' mobile satellite services, the regulatory structure for the provision of mobile satellite service on an interim basis before AMSC launches its dedicated satellites, and whether to authorize a low earth orbit satellite system to provide mobile data service.

  5. Satellite voice broadcast system study, volume 2

    NASA Technical Reports Server (NTRS)

    Horstein, M.

    1985-01-01

    This study investigates the feasibility of providing Voice of America (VOA) broadcasts by satellite relay, rather than via terrestrial relay stations. Satellite voice broadcast systems are described for three different frequency bands: HF (26 MHz), VHF (68 MHz), and L-band (1.5 GHz). The geographical areas of interest at HF and L-band include all major land masses worldwide with the exception of the U.S., Canada, and Australia. Geostationary satellite configurations are considered for both frequency bands. In addition, a system of subsynchronous, circular satellites with an orbit period of 8 hours is developed for the HF band. VHF broadcasts, which are confined to the Soviet Union, are provied by a system of Molniya satellites. Satellites intended for HF or VHF broadcastinbg are extremely large and heavy. Satellite designs presented here are limited in size and weight to the capability of the STS/Centaur launch vehicle combination. Even so, at HF it would take 47 geostationary satellites or 20 satellites in 8-hour orbits to fully satisfy the voice-channel requirements of the broadcast schedule provided by VOA. On the other hand, three Molniya satellites suffice for the geographically restricted schedule at VHF. At L-band, only four geostationary satellites are needed to meet the requirements of the complete broadcast schedule. Moreover, these satellites are comparable in size and weight to current satellites designed for direct broadcast of video program material.

  6. The future of European Communications Satellites

    NASA Astrophysics Data System (ADS)

    Morris, R.

    1984-02-01

    The paper, which is based on the work of a Eurospace Study Group on future prospects, reviews the problems arising from the introduction of new technologies in the industrial process of developing and manufacturing communications satellites, covering the topics of engineering, manufacturing, integration and test, and in-space management. It continues by considering the commerical and industrial problems encountered by European manufacturers, and the contractual and legal problems arising from the change of customer base, from ESA to user organizations, and from the political problems which stem from cross-border transmission of TV broadcasting and data transfer. It then considers the marketing problems of the spacecraft manufacturer - his remoteness from the end-user of telecommunications circuits, the competition from new technology in conventional communications, and the intense competition from U.S. competitors, who have the advantage of both military and domestic and international civil programs on which to develop technology. It concludes with a brief review of current and future spacecraft developments by British Aerospace, and some possible communications satellite configurations for the 1990's.

  7. Satellite height determination using satellite-to-satellite tracking and ground laser systems

    NASA Technical Reports Server (NTRS)

    Vonbun, F. O.

    1972-01-01

    The height of the GEOS-C spacecraft was utilized as measured by the onboard radar altimeter, for an improved determination of the earth's gravitational field and for the determination of the variation of the physical surface of the oceans. Two tracking system approaches to accurately determine the spacecraft height (orbit) are described and their results stated. These are satellite-to-satellite tracking (SST) and ground laser tracking (GLT). Height variations can be observed in the dm-regions using SST and in the m-region using present GLT.

  8. Satellite height determination using satellite-to-satellite tracking and ground laser systems

    NASA Technical Reports Server (NTRS)

    Vonbun, F. O.

    1972-01-01

    An attempt was made to use GEOS-C spacecraft height, as measured by the onboard radar altimeter, for an improved determination of the earth's gravitational field and for the determination of the variation of the physical surface of the oceans. Two tracking system approaches to accurately determine the spacecraft height (orbit) are described and their results stated. These are satellite-to-satellite tracking (SST) and ground-laser tracking (GLT). Height variations can be observed in the dm-regions using SST and in the m-region using present GLT.

  9. The Mobile Satellite Services Market.

    ERIC Educational Resources Information Center

    Anderson, Samuel

    Mobile satellite (MSAT) technology is the basis for a new component of the telecommunications industry capable of providing services to small inexpensive subscriber terminals located almost any place in the world. The market for MSAT space segment capacity (bandwidth and power) is a natural monopoly that can be logically and technically…

  10. Satellite Sees 3 Tropical Cyclones

    NASA Video Gallery

    This animation of GOES-15 satellite observations from July 8 (6:00 p.m. EDT) to July 12 (9:30 a.m. EDT), 2012, shows Hurricane Daniel weaken to a remnant low pressure area nearing Hawaii, while Emi...

  11. Medium Spatial Resolution Satellite Characterization

    NASA Technical Reports Server (NTRS)

    Stensaas, Greg

    2007-01-01

    This project provides characterization and calibration of aerial and satellite systems in support of quality acquisition and understanding of remote sensing data, and verifies and validates the associated data products with respect to ground and and atmospheric truth so that accurate value-added science can be performed. The project also provides assessment of new remote sensing technologies.

  12. Satellite monitoring of black bear.

    NASA Technical Reports Server (NTRS)

    Craighead, J. J.; Craighead, F. C., Jr.; Varney, J. R.; Cote, C. E.

    1971-01-01

    Description of a feasibility experiment recently performed to test the use of a satellite system for telemetering environmental and physiological data from the winter den of a 'hibernating' black bear, Ursus americanus. The instrumentation procedure and evaluations of the equipment performance and sensory data obtained are discussed in detail.

  13. University Satellite Campus Management Models

    ERIC Educational Resources Information Center

    Fraser, Doug; Stott, Ken

    2015-01-01

    Among the 60 or so university satellite campuses in Australia are many that are probably failing to meet the high expectations of their universities and the communities they were designed to serve. While in some cases this may be due to the demand driven system, it may also be attributable in part to the ways in which they are managed. The…

  14. Introductory Course on Satellite Navigation

    ERIC Educational Resources Information Center

    Giger, Kaspar; Knogl, J. Sebastian

    2012-01-01

    Satellite navigation is widely used for personal navigation and more and more in precise and safety-critical applications. Thus, the subject is suited for attracting the interest of young people in science and engineering. The practical applications allow catching the students' attention for the theoretical background. Educational material on the…

  15. Water Quality Monitoring by Satellite

    ERIC Educational Resources Information Center

    Journal of Chemical Education, 2004

    2004-01-01

    The availability of abundant water resources in the Upper Midwest of the United States is nullified by their contamination through heavy commercial and industrial activities. Scientists have taken the responsibility of detecting the water quality of these resources through remote-sensing satellites to develop a wide-ranging water purification plan…

  16. Technology for satellite power conversion

    NASA Technical Reports Server (NTRS)

    Campbell, D. P.; Gouker, M. A.; Summers, C.; Gallagher, J. J.

    1984-01-01

    Techniques for satellite electromagnetic energy transfer and power conversion at millimeter and infrared wavelengths are discussed. The design requirements for rectenna receiving elements are reviewed for both coherent radiation sources and Earth thermal infrared emission. Potential power transmitters including gyrotrons, free electron lasers, and CO2 lasers are assessed along with the rectification properties of metal-oxide metal diode power converters.

  17. GOES-R: Satellite Insight

    NASA Technical Reports Server (NTRS)

    Fitzpatrick, Austin J.; Leon, Nancy J.; Novati, Alexander; Lincoln, Laura K.; Fisher, Diane K.

    2012-01-01

    GOES-R: Satellite Insight seeks to bring awareness of the GOES-R (Geostationary Operational Environmental Satellite -- R Series) satellite currently in development to an audience of all ages on the emerging medium of mobile games. The iPhone app (Satellite Insight) was created for the GOES-R Program. The app describes in simple terms the types of data products that can be produced from GOES-R measurements. The game is easy to learn, yet challenging for all audiences. It includes educational content and a path to further information about GOESR, its technology, and the benefits of the data it collects. The game features action-puzzle game play in which the player must prevent an overflow of data by matching falling blocks that represent different types of GOES-R data. The game adds more different types of data blocks over time, as long as the player can prevent a data overflow condition. Points are awarded for matches, and players can compete with themselves to beat their highest score.

  18. Geosynchronous Meteorological Satellite Data Seminar

    NASA Technical Reports Server (NTRS)

    1976-01-01

    A seminar was organized by NASA to acquaint the meteorological community with data now available, and data scheduled to be available in the future, from geosynchronous meteorological satellites. The twenty-four papers were presented in three half-day sessions in addition to tours of the Image Display and LANDSAT Processing Facilities during the afternoon of the second day.

  19. Electric propulsion for small satellites

    NASA Astrophysics Data System (ADS)

    Keidar, Michael; Zhuang, Taisen; Shashurin, Alexey; Teel, George; Chiu, Dereck; Lukas, Joseph; Haque, Samudra; Brieda, Lubos

    2015-01-01

    Propulsion is required for satellite motion in outer space. The displacement of a satellite in space, orbit transfer and its attitude control are the task of space propulsion, which is carried out by rocket engines. Electric propulsion uses electric energy to energize or accelerate the propellant. The electric propulsion, which uses electrical energy to accelerate propellant in the form of plasma, is known as plasma propulsion. Plasma propulsion utilizes the electric energy to first, ionize the propellant and then, deliver energy to the resulting plasma leading to plasma acceleration. Many types of plasma thrusters have been developed over last 50 years. The variety of these devices can be divided into three main categories dependent on the mechanism of acceleration: (i) electrothermal, (ii) electrostatic and (iii) electromagnetic. Recent trends in space exploration associate with the paradigm shift towards small and efficient satellites, or micro- and nano-satellites. A particular example of microthruster considered in this paper is the micro-cathode arc thruster (µCAT). The µCAT is based on vacuum arc discharge. Thrust is produced when the arc discharge erodes some of the cathode at high velocity and is accelerated out the nozzle by a Lorentz force. The thrust amount is controlled by varying the frequency of pulses with demonstrated range to date of 1-50 Hz producing thrust ranging from 1 µN to 0.05 mN.

  20. Small satellites for tropical applications

    NASA Astrophysics Data System (ADS)

    Montpetit, Marie-Jose; Bonn, Ferdinand

    1993-11-01

    A number of mission studies were performed to assess the suitability of small satellite systems for tropical data acquisition. These studies took into account the specifics of the tropical user communities and were focused on remote sensing and resource management issues. The requirements and potential solutions for four application areas are discussed. For monitoring of forest and agricultural vegetation, a small synthetic aperture radar is considered with P, C, or X band imaging, possibly supplemented by a high resolution multispectral imager. The radar would have the capability to monitor below cloud cover which is often found in tropical regions. Optical, microwave, or spectrographic imaging would also be useful in small satellites for disaster monitoring (notably of floods), land management, and air pollution monitoring. A small satellite with data storage and forwarding capability is also envisioned to collect data from dependable, low-power, and low-cost ground sensors via a simple ultrahigh frequency uplink and download the data on a very high frequency downlink. All the small satellites would be launched in low inclination orbits to ensure a number of consecutive passes over the targeted tropical area.

  1. Monitoring disaster areas via satellites

    NASA Technical Reports Server (NTRS)

    Sivertson, W. E., Jr.

    1979-01-01

    Easily-displayed low-cost radar targets signal distress to orbiting satellites. Effective medical and evacuation efforts can be carried out successfully around globe due to this early warning. Another application is to measure rainfall, surface runoff, evaporation, and soil moisture.

  2. Atmospheric correction of satellite data

    NASA Astrophysics Data System (ADS)

    Shmirko, Konstantin; Bobrikov, Alexey; Pavlov, Andrey

    2015-11-01

    Atmosphere responses for more than 90% of all radiation measured by satellite. Due to this, atmospheric correction plays an important role in separating water leaving radiance from the signal, evaluating concentration of various water pigments (chlorophyll-A, DOM, CDOM, etc). The elimination of atmospheric intrinsic radiance from remote sensing signal referred to as atmospheric correction.

  3. Autonomous navigation for artificial satellites

    NASA Technical Reports Server (NTRS)

    Desai, P. S.

    1975-01-01

    An autonomous navigation system is considered that provides a satellite with sufficient numbers and types of sensors, as well as computational hardware and software, to enable it to track itself. Considered are attitude type sensors, meteorological cameras and scanners, one way Doppler, and image correlator.

  4. Artificial-Satellite-Analysis Program

    NASA Technical Reports Server (NTRS)

    Kwok, Johnny H.

    1989-01-01

    Artificial Satellite Analysis Program (ASAP) is general orbit-predicting computer program incorporating sufficient orbit-modeling accuracy for design and planning of missions and analysis of maneuvers. Suitable for study of planetary-orbit missions with spacecraft trajectories of reconnaissance (flyby) and exploratory (mapping) nature. Not written for specific mission and intended use for almost any planetary orbiting mission. Written in FORTRAN 77.

  5. Satellites of Mars - Geologic history

    NASA Technical Reports Server (NTRS)

    Thomas, P.; Veverka, J.; Bell, J.; Lunine, J.; Cruikshank, D.

    1992-01-01

    The small, irregularly shaped satellites of Mars, Phobos and Deimos, provide the most detailed view of the geomorphic forms and processes important on small solar system bodies. The satellites appear to be very similar in composition, strongly resembling carbonaceous asteroids; however, recent groundbased spectra suggest that their surfaces have little bound or interlayer water. Despite their similar compositions, sizes and environments, Phobos and Deimos have radically different surface features. Phobos is densely covered by craters that are nearly lunar in appearance; Deimos' craters are subdued and largely filled in by debris. Phobos shows only local downslope movement of regolith; Deimos has it on a global scale. Phobos is criss-crossed by linear depressions; Deimos has none. Crater ejecta appear to be retained near their sources on Phobos while the ejecta are widespread on Deimos. The reasons for the differences between the satellites are not known; imaging of asteroids should tell us which, if either, satellite is typical of the many small bodies that populate the asteroid belt.

  6. The DSI small satellite launcher

    NASA Technical Reports Server (NTRS)

    Nichols, S.; Gibbons, D.; Wise, J.; Nguyen, D.

    1992-01-01

    A new launcher has been developed by DSI, that is compatible with the GAS canisters. It has the proven capability to deploy a satellite from an orbiting Shuttle that is 18 inches in diameter, 31 inches long, and weighing 190 pounds. These DSI Launchers were used aboard the Discovery (STS-39) in May 1991 as part of the Infrared Background Signature Survey (IBSS) to deploy three small satellites known as Chemical Release Observation (CRO) satellites A, B, and C. Because the satellites contained hazardous liquids (MMH, UDMH, and MON-10) and were launched from GAS Cylinders without motorized doors, the launchers were required to pass NASA Shuttle Payload safety and verification requirements. Some of the more interesting components of the design were the V-band retention and separation mechanism, the separation springs, and the launcher electronics which provided a properly inhibited release sequence operated through the Small Payload Accommodations Switch Panel (SPASP) on board the Orbiter. The original plan for this launcher was to use a motorized door. The launcher electronics, therefore has the capability to be modified to accommodate the door, if desired.

  7. An Analytical Framework for Assessing the Efficacy of Small Satellites in Performing Novel Imaging Missions

    NASA Astrophysics Data System (ADS)

    Weaver, Oesa A.

    In the last two decades, small satellites have opened up the use of space to groups other than governments and large corporations, allowing for increased participation and experimentation. This democratization of space was primarily enabled by two factors: improved technology and reduced launch costs. Improved technology allowed the miniaturization of components and reduced overall cost meaning many of the capabilities of larger satellites could be replicated at a fraction of the cost. In addition, new launcher systems that could host many small satellites as ride-shares on manifested vehicles lowered launch costs and simplified the process of getting a satellite into orbit. The potential of these smaller satellites to replace or augment existing systems has led to a flood of potential satellite and mission concepts, often with little rigorous study of whether the proposed satellite or mission is achievable or necessary. This work proposes an analytical framework to aid system designers in evaluating the ability of an existing concept or small satellite to perform a particular imaging mission, either replacing or augmenting existing capabilities. This framework was developed and then refined by application to the problem of using small satellites to perform a wide area search mission -- a mission not possible with existing imaging satellites, but one that would add to current capabilities. Requirements for a wide area search mission were developed, along with a list of factors that would affect image quality and system performance. Two existing small satellite concepts were evaluated for use by examining image quality from the systems, selecting an algorithm to perform the search function automatically, and then assessing mission feasibility by applying the algorithm to simulated imagery. Finally, a notional constellation design was developed to assess the number of satellites required to perform the mission. It was found that a constellation of 480 Cube

  8. Cryovolcanism on the icy satellites

    USGS Publications Warehouse

    Kargel, J.S.

    1994-01-01

    Evidence of past cryovolcanism is widespread and extremely varied on the icy satellites. Some cryovolcanic landscapes, notably on Triton, are similar to many silicate volcanic terrains, including what appear to be volcanic rifts, calderas and solidified lava lakes, flow fields, breached cinder cones or stratovolcanoes, viscous lava domes, and sinuous rilles. Most other satellites have terrains that are different in the important respect that no obvious volcanoes are present. The preserved record of cryovolcanism generally is believed to have formed by eruptions of aqueous solutions and slurries. Even Triton's volcanic crust, which is covered by nitrogen-rich frost, is probably dominated by water ice. Nonpolar and weakly polar molecular liquids (mainly N2, CH4, CO, CO2, and Ar), may originate by decomposition of gas-clathrate hydrates and may have been erupted on some icy satellites, but without water these substances do not form rigid solids that are stable against sublimation or melting over geologic time. Triton's plumes, active at the time of Voyager 2's flyby, may consist of multicomponent nonpolar gas mixtures. The plumes may be volcanogenic fumaroles or geyserlike emissions powered by deep internal heating, and, thus, the plumes may be indicating an interior that is still cryomagmatically active; or Triton's plumes may be powered by solar heating of translucent ices very near the surface. The Uranian and Neptunian satellites Miranda, Ariel, and Triton have flow deposits that are hundreds to thousands of meters thick (implying highly viscous lavas); by contrast, the Jovian and Saturnian satellites generally have plains-forming deposits composed of relatively thin flows whose thicknesses have not been resolved in Voyager images (thus implying relatively low-viscosity lavas). One possible explanation for this inferred rheological distinction involves a difference in volatile composition of the Uranian and Neptunian satellites on one hand and of the Jovian and

  9. Cryovolcanism on the icy satellites

    NASA Astrophysics Data System (ADS)

    Kargel, J. S.

    1994-01-01

    Evidence of past cryovolcanism is widespread and extremely varied on the icy satellites. Some cryovolcanic landscapes, notably on Triton, are similar to many silicate volcanic terrains, including what appear to be volcanic rifts, calderas and solidified lava lakes, flow fields, breached cinder cones or stratovolcanoes, viscous lava domes, and sinuous rilles. Most other satellites have terrains that are different in the important respect that no obvious volcanoes are present. The preserved record of cryovolcanism generally is believed to have formed by eruptions of aqueous solutions and slurries. Even Triton's volcanic crust, which is covered by nitrogen-rich frost, is probably dominated by water ice. Nonpolar and weakly polar molecular liquids (mainly N2, CH4, CO, CO2, and Ar), may originate by decomposition of gas-clathrate hydrates and may have been erupted on some icy satellites, but without water these substances do not form rigid solids that are stable against sublimation or melting over geologic time. Triton's plumes, active at the time of Voyager 2's flyby, may consist of multicomponent nonpolar gas mixtures. The plumes may be volcanogenic fumaroles or geyserlike emissions powered by deep internal heating, and, thus, the plumes may be indicating an interior that is still cryomagmatically active; or Triton's plumes may be powered by solar heating of translucent ices very near the surface. The Uranian and Neptunian satellites Miranda, Ariel, and Triton have flow deposits that are hundreds to thousands of meters thick (implying highly viscous lavas); by contrast, the Jovian and Saturnian satellites generally have plains-forming deposits composed of relatively thin flows whose thicknesses have not been resolved in Voyager images (thus implying relatively low-viscosity lavas). One possible explanation for this inferred rheological distinction involves a difference in volatile composition of the Uranian and Neptunian satellites on one hand and of the Jovian and

  10. Satellites of LMC-mass dwarfs: close friendships ruined by Milky Way mass haloes

    NASA Astrophysics Data System (ADS)

    Deason, A. J.; Wetzel, A. R.; Garrison-Kimmel, S.; Belokurov, V.

    2015-11-01

    Motivated by the recent discovery of several dwarfs near the Large Magellanic Cloud (LMC), we study the accretion of massive satellites onto Milky Way (MW)/M31-like haloes using the ELVIS suite of N-body simulations. We identify 25 surviving LMC-mass subhaloes, and investigate the lower-mass satellites that were associated with these subhaloes before they fell into the MW/M31 haloes. Typically, 7 per cent of the overall z = 0 satellite population of MW/M31 haloes were in a surviving LMC-group before falling into the MW/M31 halo. This fraction can vary between 1 and 25 per cent, being higher for groups with higher mass and/or more recent infall times. Groups of satellites disperse rapidly in phase space after infall, and their distances and velocities relative to the group centre become statistically similar to the overall satellite population after 4-8 Gyr. We quantify the likelihood that satellites were associated with an LMC-mass group as a function of both distance and velocity relative to the LMC at z = 0. The close proximity in distance of the nine Dark Energy Survey candidate dwarf galaxies to the LMC suggest that ˜2-4 are likely associated with the LMC. Furthermore, if several of these dwarfs are genuine members, then the LMC-group probably fell into the MW very recently, ≲2 Gyr ago. If the connection with the LMC is established with follow-up velocity measurements, these `satellites of satellites' represent prime candidates to study the effects of group pre-processing on lower mass dwarfs.

  11. CCRS Landcover Maps From Satellite Data

    DOE Data Explorer

    Trishchenko, Alexander

    2008-01-15

    The Canadian Centre for Remote Sensing (CCRS) presents several landcover maps over the SGP CART site area (32-40N, 92-102W) derived from satellite data including AVHRR, MODIS, SPOT vegetation data, and Landsat satellite TM imagery.

  12. First Public Library Satellite Receiver System.

    ERIC Educational Resources Information Center

    Donaldson, Marion F.

    1982-01-01

    Description of video services at Lake County Public Library, Indiana, highlights the installation of a satellite receiver system and notes funding and justification, components of a satellite system, decisions and sources of assistance, programming available, and future considerations. (EJS)

  13. TRMM Satellite Rainfall Data on Iselle

    NASA Video Gallery

    TRMM satellite rainfall data overlaid on an enhanced infrared image from NOAA's GOES-West satellite shows heavy rainfall occurring around the Iselle's eye. The most intense rain was falling at a ra...

  14. NASA Now: Orbital Mechanics: Earth Observing Satellites

    NASA Video Gallery

    This NASA Now program is all about satellites and their orbits. Dr. James Gleason, project scientist for NPP, explains what it takes for a satellite to stay in orbit, why there are different types ...

  15. Our World: A-Train Satellites

    NASA Video Gallery

    The A-Train consists of five satellites orbiting Earth that use the latest NASA technology to study the Earth's system. This segment introduces Aqua, one of the satellites that studies water on Earth.

  16. Cloudsat and MTSAT Satellites Observer Atsani

    NASA Video Gallery

    This Aug. 19 image combines cloud imagery from Japan's MTSAT satellite and NASA's CloudSat satellite. Areas of pink and red designate larger amounts of liquid and ice. Light blue indicate smaller c...

  17. Meteorological satellites: Past, present, and future

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Past developments, accomplishments and future potential of meteorological satellites are discussed. Meteorological satellite design is described in detail. Space platforms and their meteorological applications are discussed. User needs are also discussed.

  18. NASA compendium of satellite communications programs

    NASA Technical Reports Server (NTRS)

    1971-01-01

    A comprehensive review of worldwide satellite communication programs is reported that ranges in time from the inception of satellite communications to mid-1971. Particular emphasis is placed on program results, including experiments conducted, communications system operational performance, and technology employed.

  19. TRMM Satellite Shows Heavy Rainfall in Cristina

    NASA Video Gallery

    NASA's TRMM satellite rainfall data was overlaid on an enhanced visible/infrared image from NOAA's GOES-East satellite showing cloud and rainfall extent. Green areas indicate rainfall at over 20 mm...

  20. IMPROVING BIOGENIC EMISSION ESTIMATES WITH SATELLITE IMAGERY

    EPA Science Inventory

    This presentation will review how existing and future applications of satellite imagery can improve the accuracy of biogenic emission estimates. Existing applications of satellite imagery to biogenic emission estimates have focused on characterizing land cover. Vegetation dat...

  1. Shapes, masses and interiors of satellites

    NASA Astrophysics Data System (ADS)

    Dermott, S. F.; Thomas, P. C.

    Limb-fitting methods applied to Voyager images of the satellites of Saturn have shown that some of these satellites are well-represented by triaxial ellipsoids. Furthermore, the observed ratios of the differences of the principal axes of these satellites are consistent with those values expected for synchronous satellites in hydrostatic equilibrium. For satellites of known mass, measurement of the shape leads to a determination of the satellite's moment of inertia and internal structure. The moment of inertia of Mimas determined by Dermott and Thomas (1988) shows clearly that Mimas is not homogeneous. For satellites of unknown mass, but known mantle composition, measurement of the shape can lead to a determination of the satellite's mass and mean density. This method has been successfully applied to Enceladus.

  2. GOES Weather Satellite Watches The Sun

    NASA Video Gallery

    NASA satellites such as STEREO, SOHO, and SDO are dedicated to studying the sun. GOES is a weather satellite but also watches the sun constantly. Watch this video and learn why space weather data i...

  3. Group Learning.

    ERIC Educational Resources Information Center

    Black, Susan

    1992-01-01

    Research suggests that cooperative learning works best when students are first taught group-processing skills, such as leadership, decision making, communication, trust building, and conflict management. Inadequate teacher training and boring assignments can torpedo cooperative learning efforts. Administrators should reassure teachers with…

  4. Laser beamed power: Satellite demonstration applications

    NASA Technical Reports Server (NTRS)

    Landis, Geoffrey A.; Westerlund, Larry H.

    1992-01-01

    It is possible to use a ground-based laser to beam light to the solar arrays of orbiting satellites, to a level sufficient to provide all or some of the operating power required. Near-term applications of this technology for providing supplemental power to existing satellites are discussed. Two missions with significant commercial pay-off are supplementing solar power for radiation-degraded arrays and providing satellite power during eclipse for satellites with failed batteries.

  5. Compendium of Applications Technology Satellite user experiments

    NASA Technical Reports Server (NTRS)

    Engler, N. A.; Strange, J. D.; Hein, G. F.

    1976-01-01

    The achievements of the user experiments performed with ATS satellites from 1967 to 1973 are summarized. Included are fixed and mobile point to point communications experiments involving voice, teletype and facsimile transmissions. Particular emphasis is given to the Alaska and Hawaii satellite communications experiments. The use of the ATS satellites for ranging and position fixing of ships and aircraft is also covered. The structure and operating characteristics of the various ATS satellite are briefly described.

  6. Regulatory changes for international satellite systems

    NASA Astrophysics Data System (ADS)

    Roseman, Walda W.

    Proposals for mobile and broadcast satellite systems and advances in fixed satellite systems and applications are placing new demands on governments to find efficient means of access to spectrum and create regulatory policies that facilitate the cross-border harmonization of satellite services. In an environment where liberalization is proceeding, but doing so unevenly, special responsibilities devolve to consumers and to the satellite enterprises themselves to ensure that an appropriate international regulatory framework is adopted.

  7. Earth and ocean dynamics satellites and systems

    NASA Technical Reports Server (NTRS)

    Vonbun, F. O.

    1975-01-01

    An overview is presented of the present state of satellite and ground systems making observations of the dynamics of the solid earth and the oceans. Emphasis is placed on applications of space technology for practical use. Topics discussed include: satellite missions and results over the last two decades in the areas of earth gravity field, polar motions, earth tides, magnetic anomalies, and satellite-to-satellite tracking; laser ranging systems; development of the Very Long Baseline Interferometer; and Skylab radar altimeter data applications.

  8. Engineering calculations for communications satellite systems planning

    NASA Technical Reports Server (NTRS)

    Reilly, Charles H.; Walton, Eric K.; Kohnhorst, Paul

    1987-01-01

    A procedure is described that was used to calculate minimum required satellite separations based on total link carrier to interference requirements. Also summarized are recent results with a switching algorithm for satellite synthesis problems. Analytic solution value bounds for two of the satellite synthesis models studied are described. Preliminary results from an empirical study of alternate mixed integer programming models for satellite synthesis are presented. Research plans for the near future are discussed.

  9. Icy Satellites of Saturn: Impact Cratering and Age Determination

    NASA Technical Reports Server (NTRS)

    Dones, L.; Chapman, C. R.; McKinnon, William B.; Melosh, H. J.; Kirchoff, M. R.; Neukum, G.; Zahnle, K. J.

    2009-01-01

    , and catastrophically disrupt, the saturnian moons. Finally, we present crater counts on the satellites from two different groups. Many of the heavily cratered terrains appear to be nearly saturated, so it is difficult to infer the provenance of the impactors from crater counts alone. More large craters have been found on Iapetus than on any other satellite. Enceladus displays an enormous range of surface ages, ranging from the old mid-latitude plains to the extremely young South Polar Terrain. Cassini images provide some evidence for the reality of Population II. Most of the observed craters may have formed in one or more cataclysms, but more work is needed to determine the roles of heliocentric and planetocentric bodies in creating the craters.

  10. A New Perspective: Establishing a Satellite Center for Marriage and Family Development in Married Housing.

    ERIC Educational Resources Information Center

    McKeon, Margie A.; And Others

    1980-01-01

    Reports on the development of a satellite center for marriage and family development in married housing. The background and development of the center are discussed. Models employed include the single parent group, the couples' growth group, divorce adjustment groups for children, premarital counseling, and parenting sessions. (RC)

  11. Direct-Broadcast Satellites and Cultural Integrity

    ERIC Educational Resources Information Center

    Pool, Ithiel de Sola

    1975-01-01

    Argues that progress in satellite communications depends upon the assurance that satellites are useful to people in all countries, and that a world television network and a worldwide packet data communication system would help achieve that goal, and asserts that direct-satellite television broadcasting does not represent, at present, an active…

  12. The Impact of Satellites on Cable Communications.

    ERIC Educational Resources Information Center

    Chayes, Abram

    Two recent developments in communications satellite technology may speed the coming of cable TV (CATV) networks. First, increases in satellite power are reducing the cost of ground stations. Second, a connection between one ground station, the satellite, and any other ground station is no longer necessarily fixed. Now one station can communicate…

  13. Developing a global aeronautical satellite system

    NASA Technical Reports Server (NTRS)

    Dement, Donald K.

    1988-01-01

    Arinc, an airline industry-owned and operated company in the United States, has taken steps toward establishing a global aeronautical satellite communications system. Plans call for initiation of a thin-route data operation in 1989, upgrading to establish voice communications via shared spot-beam transponders carried on other satellites, and deploying a worldwide network using dedicated satellites by 1994.

  14. 14 CFR 141.91 - Satellite bases.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Satellite bases. 141.91 Section 141.91... OTHER CERTIFICATED AGENCIES PILOT SCHOOLS Operating Rules § 141.91 Satellite bases. The holder of a... assistant chief instructor is designated for each satellite base, and that assistant chief instructor...

  15. System and Apparatus for Deploying a Satellite

    NASA Technical Reports Server (NTRS)

    Santos, Luis H. (Inventor); Hudeck, John D. (Inventor)

    2016-01-01

    A frictionless satellite constraint system is provided. The constraint system includes at least one clamp bar configured to restrain a satellite within the constraint system in an axial direction. The constraint system also includes a plurality of pins configured to restrain the satellite within the constraint system in a lateral direction.

  16. 14 CFR 141.91 - Satellite bases.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Satellite bases. 141.91 Section 141.91... OTHER CERTIFICATED AGENCIES PILOT SCHOOLS Operating Rules § 141.91 Satellite bases. The holder of a... assistant chief instructor is designated for each satellite base, and that assistant chief instructor...

  17. 14 CFR 141.91 - Satellite bases.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Satellite bases. 141.91 Section 141.91... OTHER CERTIFICATED AGENCIES PILOT SCHOOLS Operating Rules § 141.91 Satellite bases. The holder of a... assistant chief instructor is designated for each satellite base, and that assistant chief instructor...

  18. 14 CFR 141.91 - Satellite bases.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Satellite bases. 141.91 Section 141.91... OTHER CERTIFICATED AGENCIES PILOT SCHOOLS Operating Rules § 141.91 Satellite bases. The holder of a... assistant chief instructor is designated for each satellite base, and that assistant chief instructor...

  19. 14 CFR 141.91 - Satellite bases.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Satellite bases. 141.91 Section 141.91... OTHER CERTIFICATED AGENCIES PILOT SCHOOLS Operating Rules § 141.91 Satellite bases. The holder of a... assistant chief instructor is designated for each satellite base, and that assistant chief instructor...

  20. Broadcast Satellite: "Appropriate Technology" Available Now

    ERIC Educational Resources Information Center

    Norwood, Frank W.

    1978-01-01

    Experimental broadcasting satellites make possible a cooperative and inexpensive communications system for use in remote areas of the world. Considered are their historical background, news dissemination, the SITE Project in India, NASA's ATS satellites, satellite classroom instruction, and Caribbean interests. (LBH)