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Sample records for absorption esa band

  1. Atmospheric Solar Heating in Minor Absorption Bands

    NASA Technical Reports Server (NTRS)

    Chou, Ming-Dah

    1998-01-01

    Solar radiation is the primary source of energy driving atmospheric and oceanic circulations. Concerned with the huge computing time required for computing radiative transfer in weather and climate models, solar heating in minor absorption bands has often been neglected. The individual contributions of these minor bands to the atmospheric heating is small, but collectively they are not negligible. The solar heating in minor bands includes the absorption due to water vapor in the photosynthetically active radiation (PAR) spectral region from 14284/cm to 25000/cm, the ozone absorption and Rayleigh scattering in the near infrared, as well as the O2 and CO2 absorption in a number of weak bands. Detailed high spectral- and angular-resolution calculations show that the total effect of these minor absorption is to enhance the atmospheric solar heating by approximately 10%. Depending upon the strength of the absorption and the overlapping among gaseous absorption, different approaches are applied to parameterize these minor absorption. The parameterizations are accurate and require little extra time for computing radiative fluxes. They have been efficiently implemented in the various atmospheric models at NASA/Goddard Space Flight Center, including cloud ensemble, mesoscale, and climate models.

  2. Absorption band Q model for the Earth

    NASA Technical Reports Server (NTRS)

    Anderson, D. L.; Given, J. W.

    1981-01-01

    Attenuation in solids and liquids, as measured by the quality factor Q, is typically frequency dependent. In seismology, however, Q is usually assumed to be independent of frequency. Body wave, surface wave, and normal mode data are used to place constraints on the frequency dependence of Q in the mantle. Specific features of the absorption band model are: low-Q in the seismic band at both the top and the base of the mantle, low-Q for long-period body waves in the outer core, an inner core Q sub s that increases with period, and low Q sub p/Q sub s at short periods in the middle mantle.

  3. Increasing efficiency in intermediate band solar cells with overlapping absorptions

    NASA Astrophysics Data System (ADS)

    Krishna, Akshay; Krich, Jacob J.

    2016-07-01

    Intermediate band (IB) materials are promising candidates for realizing high efficiency solar cells. In IB photovoltaics, photons are absorbed in one of three possible electronic transitions—valence to conduction band, valence to intermediate band, or intermediate to conduction band. With fully concentrated sunlight, when the band gaps have been chosen appropriately, the highest efficiency IB solar cells require that these three absorptions be non-overlapping, so absorbed photons of fixed energy contribute to only one transition. The realistic case of overlapping absorptions, where the transitions compete for photons, is generally considered to be a source of loss. We show that overlapping absorptions can in fact lead to significant improvements in IB solar cell efficiencies, especially for IB that are near the middle of the band gap. At low to moderate concentration, the highest efficiency requires overlapping absorptions. We use the detailed-balance method and indicate how much overlap of the absorptions is required to achieve efficiency improvements, comparing with some known cases. These results substantially broaden the set of materials that can be suitable for high-efficiency IB solar cells.

  4. Photonic band-edge-induced enhancement in absorption and emission

    NASA Astrophysics Data System (ADS)

    Ummer, Karikkuzhi Variyath; Vijaya, Ramarao

    2015-01-01

    An enhancement in photonic band-edge-induced absorption and emission from rhodamine-B dye doped polystyrene pseudo gap photonic crystals is studied. The band-edge-induced enhancement in absorption is achieved by selecting the incident angle of the excitation beam so that the absorption spectrum of the emitter overlaps the photonic band edge. The band-edge-induced enhancement in emission, on the other hand, is possible with and without an enhancement in band-edge-induced absorption, depending on the collection angle of emission. Through a simple set of measurements with suitably chosen angles for excitation and emission, we achieve a maximum enhancement of 70% in emission intensity with band-edge-induced effects over and above the intrinsic emission in the case of self-assembled opals. This is a comprehensive effort to interpret tunable lasing in opals as well as to predict the wavelength of lasing arising as a result of band-edge-induced distributed feedback effects.

  5. Electronic Band Structure and Sub-band-gap Absorption of Nitrogen Hyperdoped Silicon

    PubMed Central

    Zhu, Zhen; Shao, Hezhu; Dong, Xiao; Li, Ning; Ning, Bo-Yuan; Ning, Xi-Jing; Zhao, Li; Zhuang, Jun

    2015-01-01

    We investigated the atomic geometry, electronic band structure, and optical absorption of nitrogen hyperdoped silicon based on first-principles calculations. The results show that all the paired nitrogen defects we studied do not introduce intermediate band, while most of single nitrogen defects can introduce intermediate band in the gap. Considering the stability of the single defects and the rapid resolidification following the laser melting process in our sample preparation method, we conclude that the substitutional nitrogen defect, whose fraction was tiny and could be neglected before, should have considerable fraction in the hyperdoped silicon and results in the visible sub-band-gap absorption as observed in the experiment. Furthermore, our calculations show that the substitutional nitrogen defect has good stability, which could be one of the reasons why the sub-band-gap absorptance remains almost unchanged after annealing. PMID:26012369

  6. Automated Extraction of Absorption Bands from Reflectance Special

    NASA Technical Reports Server (NTRS)

    Huguenin, R. L.; Vale, L.; Mcintire, D.; Jones, J.

    1985-01-01

    A multiple high order derivative spectroscopy technique has been developed for deriving wavelength positions, half widths, and heights of absorption bands in reflectance spectra. The technique is applicable to laboratory spectra as well as medium resolution (100-200/cm) telescope or spacecraft spectra with moderate (few percent) noise. The technique permits absorption band positions to be detected with an accuracy of better than 3%, and often better than 1%. The high complexity of radiative transfer processes in diffusely reflected spectra can complicate the determination of absorption band positions. Continuum reflections, random illumination geometries within the material, phase angle effects, composite overlapping bands, and calibration uncertainties can shift apparent band positions by 20% from their actual positions or mask them beyond detection. Using multiple high order derivative analysis, effects of scattering continua, phase angle, and calibration (smooth features) are suppressed. Inflection points that characterize the positions and half widths of constituent bands are enhanced by the process and directly detected with relatively high sensitivity.

  7. Absorptivity of nitric oxide in the fundamental vibrational band

    NASA Astrophysics Data System (ADS)

    Holland, R. F.; Vasquez, M. C.; Beattie, W. H.; McDowell, R. S.

    1983-05-01

    From observations of the spectral absorbance of mixtures of nitric oxide in nitrogen at room temperature, an integrated absorptivity for the NO fundamental band of 137.3 + or - 4.6 per(sq cm atm) at 0 C is derived. The indicated uncertainty is the estimated maximum error.

  8. Photodissociation of vibrationally excited water in the first absorption band

    NASA Astrophysics Data System (ADS)

    Weide, Klaus; Hennig, Steffen; Schinke, Reinhard

    1989-12-01

    We investigate the photodissociation of highly excited vibrational states of water in the first absorption band. The calculation includes an ab initio potential energy surface for the Östate and an ab initio X˜→Ã transition dipole function. The bending angle is fixed at the equilibrium value within the ground electronic state. Most interesting is the high sensitivity of the final vibrational distribution of OH on the initially prepared vibrational state of H2 O. At wavelengths near the onset of the absorption spectrum the vibrational state distribution can be qualitatively understood as a Franck-Condon mapping of the initial H2 O wave function. At smaller wavelengths final state interaction in the excited state becomes stronger and the distributions become successively broader. Our calculations are in satisfactory accord with recent measurements of Vander Wal and Crim.

  9. Optical absorption of nanoporous silicon: quasiparticle band gaps and absorption spectra

    NASA Astrophysics Data System (ADS)

    Shi, Guangsha; Kioupakis, Emmanouil

    2013-03-01

    Silicon is an earth-abundant material of great importance in semiconductors electronics, but its photovoltaic applications are limited by the low absorption coefficient in the visible due to its indirect band gap. One strategy to improve the absorbance is to perforate silicon with nanoscale pores, which introduce carrier scattering that enables optical transitions across the indirect gap. We used density functional and many-body perturbation theory in the GW approximation to investigate the electronic and optical properties of porous silicon for various pore sizes, spacings, and orientations. Our calculations include up to 400 atoms in the unit cell. We will discuss the connection of the band-gap value and absorption coefficient to the underlying nanopore geometry. The absorption coefficient in the visible range is found to be optimal for appropriately chosen nanopore size, spacing, and orientation. Our work allows us to predict porous-silicon structures that may have optimal performance in photovoltaic applications. This research was supported as part of CSTEC, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science. Computational resources were provided by the DOE NERSC facility.

  10. Propane absorption band intensities and band model parameters from 680 to 1580/cm at 296 and 200 K

    NASA Technical Reports Server (NTRS)

    Giver, L. P.; Valero, F. P. J.; Varanasi, P.

    1984-01-01

    Band intensities and profiles have been measured for the propane absorption bands from 680 to 1580/cm at 296 and 200 K. This work was stimulated by the discovery of several propane bands in the spectrum of Titan by the Voyager 1 spacecraft. The low temperature laboratory data show that the bands become narrower and the Q branches of the bands somewhat stronger than they are at room temperature. Random band model parameters were determined over the entire region from the 42 spectra obtained at room temperature.

  11. Enhanced dual-band infrared absorption in a Fabry-Perot cavity with subwavelength metallic grating.

    PubMed

    Kang, Guoguo; Vartiainen, Ismo; Bai, Benfeng; Turunen, Jari

    2011-01-17

    The performance of infrared (IR) dual-band detector can be substantially improved by simultaneously increasing IR absorptions for both sensor bands. Currently available methods only provide absorption enhancement for single spectral band, but not for the dual-band. The Fabry-Perot (FP) cavity generates a series of resonances in multispectral bands. With this flexibility, we introduced a novel type of dual-band detector structure containing a multilayer FP cavity with two absorbing layers and a subwavelength-period grating mirror, which is capable of simultaneously enhancing the middle wave infrared (MWIR) and the long wave infrared (LWIR) detection. Compared with the bare-absorption-layer detector (common dual-band detector), the optimized FP cavity can provide about 13 times and 17 times absorption enhancement in LWIR and MWIR bands respectively. PMID:21263618

  12. ESA Sky

    NASA Astrophysics Data System (ADS)

    Merin, Bruno

    2015-12-01

    The ESAC Science Data Centre, ESDC, is working on a science-driven discovery portal for all its astronomy missions with the provisional name Multi-Mission Interface. The first public release of this service will be demonstrated, featuring an interface for sky exploration and for single and multiple target searches. It requires no prior knowledge of any of the missions involved. From a technical point of view, the system offers all-sky projections of full mission datasets using a new-generation HEALPix projection called HiPS; detailed geometrical footprints to access individual observations at the mission archives using VO-TAP queries; and direct access to the underlying mission-specific science archives. A first public release is scheduled before the end of 2015 and will give users worldwide simplified access to high-level science-ready data products from all ESA Astronomy missions plus a number of ESA-produced source catalogues. A demo will accompany the presentation.

  13. Absorption coefficients and band strengths for the 703 nm and 727 bands of methane at 77 K

    SciTech Connect

    O`Brien, J.J.; Singh, K.

    1996-12-31

    The technique of intracavity laser spectroscopy has been used to obtain methane absorption spectra for the vibrational overtone bands that occur around 703 nm and 727 nm. Absorption coefficients for the 690-742 nm range have been obtained for a sample temperature of 77 K at a spectral resolution of <0.02 cm{sup -1}. A new method of data analysis is utilized in obtaining the results. It involves deconvolving the many ILS spectral profiles that comprise the absorption bands and summing the results. Values averaged over 1 cm{sup -1} and 1 {Angstrom} intervals are provided. Band strengths also are obtained. The total intensities of the 703 and 727 nm bands are in reasonable agreement with previous laboratory determinations which were obtained for relatively high pressures of methane at room temperature using lower spectral resolution. The methane bands appear in the reflected sunlight spectra from the outer planets. Results averaged over 1 nm intervals are compared with other laboratory studies and with those derived from observations of the outer planets. The band profiles differ considerably from other laboratory results but are in good accord with the planetary observations. Laboratory spectra of methane at appropriate conditions are required for the proper interpretation of the observational data. Absorption spectra can provide some of the most sensitive diagnostic data on the atmospheres of those bodies.

  14. Removal of OH Absorption Bands Due to Pyrohydrolysis Reactions in Fluoride-Containing Borosilicate Glasses

    NASA Astrophysics Data System (ADS)

    Kobayashi, Keiji

    1997-05-01

    The purpose of this study is to decrease and to remove OH ions and H2O in borosilicate glasses. Fluoride-containing borosilicate glasses followed by dry-air-bubbling showed the significant decrease of OH absorption bands around 3500 cm-1. The decrease of OH absorption bands was elucidated by the use of pyrohydrolysis reactions in these glasses where fluoride ions react with OH ions or H2O during melting. The rates of the decrease of OH absorption bands substantially depend on high valence cations of fluorides. Particularly, the decrease rates of OH absorption coefficients were in the order of ZrF4-containing glass>AlF3-containing glass>ZnF2-containing glass. ZrF4-containing glass treated by dry-air-bubbling showed a good capability to remove OH absorption band. Fluoride-containing glasses showed the low flow point in comparison with fluoride-free glasses.

  15. Experimental study of absorption band controllable planar metamaterial absorber using asymmetrical snowflake-shaped configuration

    NASA Astrophysics Data System (ADS)

    Huang, Yongjun; Tian, Yiran; Wen, Guangjun; Zhu, Weiren

    2013-05-01

    In this paper, we systematically discuss a novel planar metamaterial absorber (PMA) based on asymmetrical snowflake-shaped resonators, which can exhibit two distinctly different absorption states, single- and dual-band absorptions, by controlling the branch lengths of the proposed resonators. Numerical simulations and experimental measurements are employed to investigate these two kinds of absorption characteristic in an X-band rectangular waveguide. Both results indicate that such a PMA exhibits a wide range of controllable operating frequencies for the single- and dual-band conditions. The proposed PMA is simple and easy to make, and it has wide applications in the fields of stealth technologies, thermal detectors, and imaging.

  16. Observation of temperature dependence of the IR hydroxyl absorption bands in silica optical fiber

    NASA Astrophysics Data System (ADS)

    Yu, Li; Bonnell, Elizabeth; Homa, Daniel; Pickrell, Gary; Wang, Anbo; Ohodnicki, P. R.; Woodruff, Steven; Chorpening, Benjamin; Buric, Michael

    2016-07-01

    This study reports on the temperature dependent behavior of silica based optical fibers upon exposure to high temperatures in hydrogen and ambient air. The hydroxyl absorption bands in the wavelength range of 1000-2500 nm of commercially available multimode fibers with pure silica and germanium doped cores were examined in the temperature range of 20-800 °C. Two hydroxyl-related infrared absorption bands were observed: ∼2200 nm assigned to the combination of the vibration mode of Si-OH bending and the fundamental hydroxyl stretching mode, and ∼1390 nm assigned to the first overtone of the hydroxyl stretching. The absorption in the 2200 nm band decreased in intensity, while the 1390 nm absorption band shifted to longer wavelengths with an increase in temperature. The observed phenomena were reversible with temperature and suspected to be due, in part, to the conversion of the OH spectral components into each other and structural relaxation.

  17. Position and Confidence Limits of an Extremum: The Determination of the Absorption Maximum in Wide Bands.

    ERIC Educational Resources Information Center

    Heilbronner, Edgar

    1979-01-01

    Discusses the determination of the position of the absorption maximum in wide bands as well as the confidence limits for such calculations. A simple method, suited for pocket calculators, for the numerical evaluation of these calculations is presented. (BB)

  18. HAC: Band Gap, Photoluminescence, and Optical/Near-Infrared Absorption

    NASA Technical Reports Server (NTRS)

    Witt, Adolf N.; Ryutov, Dimitri; Furton, Douglas G.

    1996-01-01

    We report results of laboratory measurements which illustrate the wide range of physical properties found among hydrogenated amorphous carbon (HAC) solids. Within this range, HAC can match quantitatively the astronomical phenomena ascribed to carbonaceous coatings on interstellar grains. We find the optical band gap of HAC to be well correlated with other physical properties of HAC of astronomical interest, and conclude that interstellar HAC must be fairly hydrogen-rich with a band gap of E(sub g) is approx. greater than 2.0 eV.

  19. Cause of absorption band shift of disperse red-13 attached on silica spheres

    NASA Astrophysics Data System (ADS)

    Kim, Byoung-Ju; Kim, Hyung-Deok; Kim, Na-Rae; Bang, Byeong-Gyu; Park, Eun-Hye; Kang, Kwang-Sun

    2015-08-01

    A reversible color change and large absorption band shift have been observed for the disperse red-13 (DR-13) attached on the surface of the monodisperse silica spheres. Two step synthetic processes including urethane bond formation and hydrolysis-condensation reactions were used to attach the DR-13 on the surface of the silica spheres. After the reaction, the characteristic absorption peak at 2270 cm-1 representing the -N=C=O asymmetric stretching vibration disappeared, and the a new absorption peak at 1700 cm-1 corresponding the C=O stretching vibration appeared. A visual and reversible color change was observed before and after wetting in alcohol. Although the absorption peak of DR-13 in alcohol is at 510 nm, the absorption peak shifts to 788 nm when it is dried. The absorption peak shifts to 718 nm when it is wetted in alcohol. This result can be explained by the formation of intramolecular charge transfer band.

  20. Atmospheric absorption of high frequency noise and application to fractional-octave bands

    NASA Technical Reports Server (NTRS)

    Shields, F. D.; Bass, H. E.

    1977-01-01

    Pure tone sound absorption coefficients were measured at 1/12 octave intervals from 4 to 100 KHz at 5.5K temperature intervals between 255.4 and 310.9 K and at 10 percent relative humidity increments between 0 percent and saturation in a large cylindrical tube (i.d., 25.4 cm; length, 4.8 m). Special solid-dielectric capacitance transducers, one to generate bursts of sound waves and one to terminate the sound path and detect the tone bursts, were constructed to fit inside the tube. The absorption was measured by varying the transmitter receiver separation from 1 to 4 m and observing the decay of multiple reflections or change in amplitude of the first received burst. The resulting absorption was compared with that from a proposed procedure for computing sound absorption in still air. Absorption of bands of noise was numerically computed by using the pure tone results. The results depended on spectrum shape, on filter type, and nonlinearly on propagation distance. For some of the cases considered, comparison with the extrapolation of ARP-866A showed a difference as large as a factor of 2. However, for many cases, the absorption for a finite band was nearly equal to the pure tone absorption at the center frequency of the band. A recommended prediction procedure is described for 1/3 octave band absorption coefficients.

  1. Evidence for sulphur implantation in Europa's UV absorption band

    NASA Technical Reports Server (NTRS)

    Lane, A. L.; Nelson, R. M.; Matson, D. L.

    1981-01-01

    The UV spectral characteristics of the Galilean satellites are investigated (using data from the International Ultraviolet Explorer (IUE) spacecraft) as a function of the orbital position, large-scale areal variability, and temporal dynamics. The discovery of an absorption feature at 280 nm in Europa's reflection spectrum is reported and observations show that the absorption is strongest on the trailing hemisphere (central longitude 270 degrees). The feature resembles SO2 and seems to result from S-O bond formation between deeply implanted sulphur atoms and the adjacent damaged water-ice-lattice. The sulphur supposedly comes from energetic (hundreds of keV) sulphur ions that are present in the Jovian magnetosphere. An appropriate equilibrium condition can be found to match the observed spectral data if sputtering erosion occurs at no greater than approximately 20 meters per one billion years.

  2. Nonequilibrium Green's function formulation of intersubband absorption for nonparabolic single-band effective mass Hamiltonian

    SciTech Connect

    Kolek, Andrzej

    2015-05-04

    The formulas are derived that enable calculations of intersubband absorption coefficient within nonequilibrium Green's function method applied to a single-band effective-mass Hamiltonian with the energy dependent effective mass. The derivation provides also the formulas for the virtual valence band components of the two-band Green's functions which can be used for more exact estimation of the density of states and electrons and more reliable treatment of electronic transport in unipolar n-type heterostructure semiconductor devices.

  3. Possible spinel absorption bands in S-asteroid visible reflectance spectra

    NASA Technical Reports Server (NTRS)

    Hiroi, T.; Vilas, F.; Sunshine, J. M.

    1994-01-01

    Minor absorption bands in the 0.55 to 0.7 micron wavelength range of reflectance spectra of 10 S asteroids have been found and compared with those of spinel-group minerals using the modified Gaussian model. Most of these S asteroids are consistently shown to have two absorption bands around 0.6 and 0.67 micron. Of the spinel-group minerals examined in this study, the 0.6 and 0.67 micron bands are most consistent with those seen in chromite. Recently, the existence of spinels has also been detected from the absorption-band features around 1 and 2 micron of two S-asteroid reflectance spectra, and chromite has been found in a primitive achondrite as its major phase. These new findings suggest a possible common existence of spinel-group minerals in the solar system.

  4. Varied absorption peaks of dual-band metamaterial absorber analysis by using reflection theory

    NASA Astrophysics Data System (ADS)

    Xiong, Han; Yu, Yan-Tao; Tang, Ming-Chun; Chen, Shi-Yong; Liu, Dan-Ping; Ou, Xiang; Zeng, Hao

    2016-03-01

    Cross-resonator metamaterial absorbers (MMA) have been widely investigated from microwave to optical frequencies. However, only part of the factors influencing the absorption properties were analyzed in previous works at the same time. In order to completely understand how the spacer thickness, dielectric parameter and incidence angle affect the absorption properties of the dual-band MMA, two sets of simulation were performed. It was found that with increasing incident angles, the low-frequency absorption peak showed a blue shift, while the high-frequency absorption peaks showed a red shift. However, with the increase in spacer thickness, both of the absorption peaks showed a red shift. By using the reflection theory expressions, the physical mechanism of the cross-resonator MMA was well explained. This method provides an effective way to analyze multi-band absorber in technology.

  5. Measurement of the depolarization ratio of Rayleigh scattering at absorption bands

    NASA Astrophysics Data System (ADS)

    Anglister, J.; Steinberg, I. Z.

    1981-01-01

    Measurements of the depolarization ratio ρv of light scattered by the pigments lycopene and β-carotene at the red part of their absorption bands yielded values which are very close to the theoretical value 1/3 of a fully anisotropic molecular polarizability, i.e., that due to an electric dipole moment. Measurements of ρv at the blue edge of the visible absorption band of pinacyanol chloride yielded a value of 0.75 at 472.2 nm, which is the maximum value that a depolarization ratio can assume, and is attained if the average molecular polarizability is zero. This is possible only if the diagonalized polarizability tensor has at least one negative element to counterbalance the positive ones. A negative refractive index at the blue edge of the absorption band is thus experimentally demonstrated.

  6. AKARI observations of ice absorption bands towards edge-on YSOs

    NASA Astrophysics Data System (ADS)

    Aikawa, Y.; Kamuro, D.; Sakon, I.; Itoh, Y.; Noble, J. A.; Pontoppidan, K. M., Fraser, H. J.; Terada, H.; Tamura, M.; Kandori, R.; Kawamura, A.; Ueno, M.

    2011-05-01

    Circumstellar disks and envelopes of low-mass YSOs contain significant amounts of ice. Such icy material will evolve to volatile components of planetary systems, such as comets in our solar system. In order to investigate the composition and evolution of circumstellar ice around low-mass YSOs, we have observed ice absorption bands towards eight YSOs ranging from class 0 to class II, among which seven are associated with edge-on disks. Slit-less spectroscopic observations are performed using the grism mode of Infrared Camera (IRC) on board AKARI, which enables us to obtain full NIR spectra from 2.5 μm to 5 μm, including the CO_2 band and the blue wing of the H_2O band, which are not accessible from the ground. We developed procedures to reduce the spectra of targets with nebulosity. The spectra are fitted with polynomial baselines to derive the absorption spectra. Then we fit the molecular absorption bands with the laboratory spectra from the database, considering the instrumental line profile and the spectral resolution of the dispersion element. Towards the Class 0-I sources, absorption bands of H_2O, CO_2, CO and XCN (OCN^-) are clearly detected. Weak features of 13CO_2, HDO, the C-H band, and gaseous CO are detected as well. OCS ice absorption is tentatively detected towards IRC-L1041-2. The detected features would mostly originate in the cold envelope, while CO gas and OCN^- could originate in the region close to the protostar. Towards class II stars, H_2O ice band is detected. We also detected H_2O ice, CO_2 ice and tentative CO gas features of the foreground component of class II stars.

  7. Millimeter Wave Absorption Bands of Silver/copper Iodides-Phosphate Glasses

    NASA Astrophysics Data System (ADS)

    Awano, Teruyoshi; Takahashi, Toshiharu

    2013-07-01

    Millimeter wave absorption spectra of silver halides doped silver phosphate glasses were measured using an intense coherent transition radiation. Two bands were observed at 8.4cm-1 and 6.3cm-1 in AgI doped AgPO3 glass and 8.7cm-1 and 6.1cm-1 in AgBr doped one. Small difference of peak positions between these glasses suggests that these absorption bands are concerned with a large number of silver ions in dopant molecules. Cu+ conducting glasses

  8. Broadening of absorption band by coupled gap plasmon resonances in a near-infrared metamaterial absorber

    NASA Astrophysics Data System (ADS)

    Cong, Jiawei; Yao, Hongbing; Gong, Daolei; Chen, Mingyang; Tong, Yanqun; Fu, Yonghong; Ren, Naifei

    2016-07-01

    We propose a strategy to broaden the absorption band of the conventional metamaterial absorber by incorporating alternating metal/dielectric films. Up to 7-fold increase in bandwidth and ∼95% average absorption are achieved arising from the coupling of induced multiple gap plasmon resonances. The resonance coupling is analytically demonstrated using the coupled oscillator model, which reveals that both the optimal coupling strength and the resonance wavelength matching are required for the enhancement of absorption bandwidth. The presented multilayer design is easily fabricated and readily implanted to other absorber configurations, offering a practical avenue for applications in photovoltaic cells and thermal emitters.

  9. High sensitivity ultra-broad-band absorption spectroscopy of inductively coupled chlorine plasma

    NASA Astrophysics Data System (ADS)

    Marinov, Daniil; Foucher, Mickaël; Campbell, Ewen; Brouard, Mark; Chabert, Pascal; Booth, Jean-Paul

    2016-06-01

    We propose a method to measure the densities of vibrationally excited Cl2(v) molecules in levels up to v  =  3 in pure chlorine inductively coupled plasmas (ICPs). The absorption continuum of Cl2 in the 250–450 nm spectral range is deconvoluted into the individual components originating from the different vibrational levels of the ground state, using a set of ab initio absorption cross sections. It is shown that gas heating at constant pressure is the major depletion mechanism of the Cl2 feedstock in the plasma. In these line-integrated absorption measurements, the absorption by the hot (and therefore rarefied) Cl2 gas in the reactor centre is masked by the cooler (and therefore denser) Cl2 near the walls. These radial gradients in temperature and density make it difficult to assess the degree of vibrational excitation in the centre of the reactor. The observed line-averaged vibrational distributions, when analyzed taking into account the radial temperature gradient, suggest that vibrational and translational degrees of freedom in the plasma are close to local equilibrium. This can be explained by efficient vibrational-translational (VT) relaxation between Cl2 and Cl atoms. Besides the Cl2(v) absorption band, a weak continuum absorption is observed at shorter wavelengths, and is attributed to photodetachment of Cl‑ negative ions. Thus, line-integrated densities of negative ions in chlorine plasmas can be directly measured using broad-band absorption spectroscopy.

  10. Diversity in the Visible-NIR Absorption Band Characteristics of Lunar and Asteroidal Plagioclase

    NASA Technical Reports Server (NTRS)

    Hiroi, T.; Kaiden, H.; Misawa, K.; Kojima, H.; Uemoto, K.; Ohtake, M.; Arai, T.; Sasaki, S.; Takeda, H.; Nyquist, L. E.; Shih, C.-Y.

    2012-01-01

    Studying the visible and near-infrared (VNIR) spectral properties of plagioclase has been challenging because of the difficulty in obtaining good plagioclase separates from pristine planetary materials such as meteorites and returned lunar samples. After an early study indicated that the 1.25 m band position of plagioclase spectrum might be correlated with the molar percentage of anorthite (An#) [1], there have been few studies which dealt with the band center behavior. In this study, the VNIR absorption band parameters of plagioclase samples have been derived using the modified Gaussian model (MGM) [2] following a pioneering study by [3].

  11. Infrared band absorptance correlations and applications to nongray radiation. [mathematical models of absorption spectra for nongray atmospheres in order to study air pollution

    NASA Technical Reports Server (NTRS)

    Tiwari, S. N.; Manian, S. V. S.

    1976-01-01

    Various mathematical models for infrared radiation absorption spectra for atmospheric gases are reviewed, and continuous correlations for the total absorptance of a wide band are presented. Different band absorptance correlations were employed in two physically realistic problems (radiative transfer in gases with internal heat source, and heat transfer in laminar flow of absorbing-emitting gases between parallel plates) to study their influence on final radiative transfer results. This information will be applied to the study of atmospheric pollutants by infrared radiation measurement.

  12. Laboratory Measurements of the 940, 1130, and 1370 nm Water Vapor Absorption Band Profiles

    NASA Technical Reports Server (NTRS)

    Giver, Lawrence P.; Gore, Warren J.; Pilewskie, P.; Freedman, R. S.; Chackerian, C., Jr.; Varanasi, P.

    2001-01-01

    We have used the solar spectral flux radiometer (SSFR) flight instrument with the Ames 25 meter base-path White cell to obtain about 20 moderate resolution (8 nm) pure water vapor spectra from 650 to 1650 nm, with absorbing paths from 806 to 1506 meters and pressures up to 14 torr. We also obtained a set at 806 meters with several different air-broadening pressures. Model simulations were made for the 940, 1130, and 1370 nm absorption bands for some of these laboratory conditions using the Rothman, et al HITRAN-2000 linelist. This new compilation of HITRAN includes new intensity measurements for the 940 nm region. We compared simulations for our spectra of this band using HITRAN-2000 with simulations using the prior HITRAN-1996. The simulations of the 1130 nm band show about 10% less absorption than we measured. There is some evidence that the total intensity of this band is about 38% stronger than the sum of the HITRAN line intensities in this region. In our laboratory conditions the absorption depends approximately on the square root of the intensity. Thus, our measurements agree that the band is stronger than tabulated in HITRAN, but by about 20%, substantially less than the published value. Significant differences have been shown between Doppler-limited resolution spectra of the 1370 nm band obtained at the Pacific Northwest National Laboratory and HITRAN simulations. Additional new intensity measurements in this region are continuing to be made. We expect the simulations of our SSFR lab data of this band will show the relative importance of improving the HITRAN line intensities of this band for atmospheric measurements.

  13. Isothermal annealing of a 620 nm optical absorption band in Brazilian topaz crystals

    NASA Astrophysics Data System (ADS)

    Isotani, Sadao; Matsuoka, Masao; Albuquerque, Antonio Roberto Pereira Leite

    2013-04-01

    Isothermal decay behaviors, observed at 515, 523, 562, and 693 K, for an optical absorption band at 620 nm in gamma-irradiated Brazilian blue topaz were analyzed using a kinetic model consisting of O- bound small polarons adjacent to recombination centers (electron traps). The kinetic equations obtained on the basis of this model were solved using the method of Runge-Kutta and the fit parameters describing these defects were determined with a grid optimization method. Two activation energies of 0.52±0.08 and 0.88±0.13 eV, corresponding to two different structural configurations of the O- polarons, explained well the isothermal decay curves using first-order kinetics expected from the kinetic model. On the other hand, thermoluminescence (TL) emission spectra measured at various temperatures showed a single band at 400 nm in the temperature range of 373-553 K in which the 620 nm optical absorption band decreased in intensity. Monochromatic TL glow curve data at 400 nm extracted from the TL emission spectra observed were found to be explained reasonably by using the knowledge obtained from the isothermal decay analysis. This suggests that two different structural configurations of O- polarons are responsible for the 620 nm optical absorption band and that the thermal annealing of the polarons causes the 400 nm TL emission band.

  14. Band-integrated infrared absorptance of low-molecular-weight paraffin hydrocarbons at high temperatures.

    PubMed

    Fuss, S P; Hall, M J; Ezekoye, O A

    1999-05-01

    The spectral absorptance of the 3.4-microm band of methane, ethane, propane, and butane has been measured with a Fourier transform infrared spectrometer over a range of temperatures from 296 to 900 K. The measurements were made at a 4-cm(-1) resolution and integrated over the entire band to give the total absorptance. The total absorptance is found to behave in such a way that it can be correlated by a combination of algebraic expressions that depend on the gas temperature and concentration. Average discrepancies between the correlations and the measurements are less than 4%, with maximum differences of no greater than 17%. In addition, the correlations presented here for methane are shown to be in good agreement with established models. Expressions given for the integrated intensity of each gas show an inverse dependence on temperature, reflecting the associated change in density. PMID:18319871

  15. Effect of Sn on the optical band gap determined using absorption spectrum fitting method

    SciTech Connect

    Heera, Pawan; Kumar, Anup; Sharma, Raman

    2015-05-15

    We report the preparation and the optical studies on tellurium rich glasses thin films. The thin films of Se{sub 30}Te{sub 70-x} Sn{sub x} system for x= 0, 1.5, 2.5 and 4.5 glassy alloys prepared by melt quenching technique are deposited on the glass substrate using vacuum thermal evaporation technique. The analysis of absorption spectra in the spectral range 400nm–4000 nm at room temperature obtained from UV-VIS-NIR spectrophotometer [Perkin Elmer Lamda-750] helps us in the optical characterization of the thin films under study. The absorption spectrum fitting method is applied by using the Tauc’s model for estimating the optical band gap and the width of the band tail of the thin films. The optical band gap is calculated and is found to decrease with the Sn content.

  16. Understanding of sub-band gap absorption of femtosecond-laser sulfur hyperdoped silicon using synchrotron-based techniques

    NASA Astrophysics Data System (ADS)

    Limaye, Mukta V.; Chen, S. C.; Lee, C. Y.; Chen, L. Y.; Singh, Shashi B.; Shao, Y. C.; Wang, Y. F.; Hsieh, S. H.; Hsueh, H. C.; Chiou, J. W.; Chen, C. H.; Jang, L. Y.; Cheng, C. L.; Pong, W. F.; Hu, Y. F.

    2015-06-01

    The correlation between sub-band gap absorption and the chemical states and electronic and atomic structures of S-hyperdoped Si have been extensively studied, using synchrotron-based x-ray photoelectron spectroscopy (XPS), x-ray absorption near-edge spectroscopy (XANES), extended x-ray absorption fine structure (EXAFS), valence-band photoemission spectroscopy (VB-PES) and first-principles calculation. S 2p XPS spectra reveal that the S-hyperdoped Si with the greatest (~87%) sub-band gap absorption contains the highest concentration of S2- (monosulfide) species. Annealing S-hyperdoped Si reduces the sub-band gap absorptance and the concentration of S2- species, but significantly increases the concentration of larger S clusters [polysulfides (Sn2-, n > 2)]. The Si K-edge XANES spectra show that S hyperdoping in Si increases (decreased) the occupied (unoccupied) electronic density of states at/above the conduction-band-minimum. VB-PES spectra evidently reveal that the S-dopants not only form an impurity band deep within the band gap, giving rise to the sub-band gap absorption, but also cause the insulator-to-metal transition in S-hyperdoped Si samples. Based on the experimental results and the calculations by density functional theory, the chemical state of the S species and the formation of the S-dopant states in the band gap of Si are critical in determining the sub-band gap absorptance of hyperdoped Si samples.

  17. AKARI observations of ice absorption bands towards edge-on young stellar objects

    NASA Astrophysics Data System (ADS)

    Aikawa, Y.; Kamuro, D.; Sakon, I.; Itoh, Y.; Terada, H.; Noble, J. A.; Pontoppidan, K. M.; Fraser, H. J.; Tamura, M.; Kandori, R.; Kawamura, A.; Ueno, M.

    2012-02-01

    Context. Circumstellar disks and envelopes of low-mass young stellar objects (YSOs) contain significant amounts of ice. Such icy material will evolve to become volatile components of planetary systems, such as comets in our solar system. Aims: To investigate the composition and evolution of circumstellar ice around low-mass young stellar objects (YSOs), we observed ice absorption bands in the near infrared (NIR) towards eight YSOs ranging from class 0 to class II, among which seven are associated with edge-on disks. Methods: We performed slit-less spectroscopic observations using the grism mode of the InfraRed Camera (IRC) on board AKARI, which enables us to obtain full NIR spectra from 2.5 μm to 5 μm, including the CO2 band and the blue wing of the H2O band, which are inaccessible from the ground. We developed procedures to carefully process the spectra of targets with nebulosity. The spectra were fitted with polynomial baselines to derive the absorption spectra. The molecular absorption bands were then fitted with the laboratory database of ice absorption bands, considering the instrumental line profile and the spectral resolution of the grism dispersion element. Results: Towards the class 0-I sources (L1527, IRC-L1041-2, and IRAS 04302), absorption bands of H2O, CO2, CO, and XCN are clearly detected. Column density ratios of CO2 ice and CO ice relative to H2O ice are 21-28% and 13-46%, respectively. If XCN is OCN-, its column density is as high as 2-6% relative to H2O ice. The HDO ice feature at 4.1 μm is tentatively detected towards the class 0-I sources and HV Tau. Non-detections of the CH-stretching mode features around 3.5 μm provide upper limits to the CH3OH abundance of 26% (L1527) and 42% (IRAS 04302) relative to H2O. We tentatively detect OCS ice absorption towards IRC-L1041-2. Towards class 0-I sources, the detected features should mostly originate in the cold envelope, while CO gas and OCN- could originate in the region close to the protostar

  18. Radiation absorption by the C2 band systems for Jupiter entry conditions

    NASA Technical Reports Server (NTRS)

    Sutton, K.; Moss, J. N.

    1979-01-01

    Revised values of the absorption cross sections for seven electronic band systems of C2 have been calculated using recently published experimental data for the electronic transition moments. Using these revised C2 cross section values, computations were made for the radiating flow field over a Jupiter entry probe with coupled ablation injection from a carbon-phenolic heat shield. Results are presented which show that radiation absorption within the ablation layer for the spectral range of 4 to 6 eV is less than that predicted using previous C2 absorption cross section values. The effect of the reduced radiation absorption by the C2 molecule is an increase in the radiative heating rates and ablation mass loss rates for the Jupiter entry conditions considered in the study.

  19. Absorption spectrum of NO in the {gamma}(O, O) band

    SciTech Connect

    Zobnin, A.V.; Korotkov, A.N.

    1995-05-01

    A promising technique for determining the concentration of nitrogen oxide in the air of an industrial zone and in process gases is the measurement of the absorption of UV radiation by this molecule in the {gamma}(O,O) band with the center of {lambda}{sub 0} = 226.5 nm. This band corresponds to the transition X{sup 2}{Pi}{yields}{Alpha}{sup 2}{Sigma} of the NO molecule and is characterized by a complex rotational structure consisting of about 400 lines. This structure cannot be resolved completely by most spectral instruments. However, if the width of the spread function of the device is perceptibly smaller than the width of the given absorption band ({approx_equal}2 nm), but larger than the characteristic space between rotational lines ({approx_equal}0.02 nm), then the recorded transmission spectra of NO are almost insensitive to a change in the form of this function. In the given case, to describe the transmission spectrum it is possible to use the absorption coefficient averaged over rotational lines. And even though the Bouger-Lambert-Beer law is not strictly applicable for this spectrum, the dependence of the transmission spectrum of NO on the optical thickness, temperature, and pressure of the broadening gas can be represented in the form of an empirical dependence that can be useful in practice, for example, when processing the absorption spectra recorded by dispersion gas analyzers. Thus, the need for complex and laborious calculations is avoided, and this simplifies considerably the instrumental implementation of this method of measuring the concentration of NO. The object of the present work is to determine the empirical dependence of the absorption spectrum of NO in the {gamma}(O, O) band on the optical thickness, temperature, and pressure of the broadening gas in the ranges most frequently encountered in operation of dispersion gas analyzers.

  20. Novel Cross-Band Relative Absorption (CoBRA) technique For Measuring Atmospheric Species

    NASA Astrophysics Data System (ADS)

    Prasad, N. S.; Pliutau, D.

    2013-12-01

    We describe a methodology called Cross-Band Relative Absorption (CoBRA) we have implemented to significantly reduce interferences due to variations in atmospheric temperature and pressure in molecular mixing ration measurements [1-4]. The interference reduction is achieved through automatic compensation based on selecting spectral line pairs exhibiting similar evolution behavior under varying atmospheric conditions. The method is applicable to a wide range of molecules including CO2 and CH4 which can be matched with O2 or any other well-mixed atmospheric molecule. Such matching results in automatic simultaneous adjustments of the spectral line shapes at all times with a high precision under varying atmospheric conditions of temperature and pressure. We present the results of our selected CoBRA analysis based on line-by-line calculations and the Modern Era Retrospective Analysis for Research and Applications (MERRA) dataset including more recent evaluation of the error contributions due to water vapor interference effects. References: 1) N. S. Prasad, D. Pliutau, 'Cross-band relative absorption technique for the measurement of molecular mixing ratios.', Optics Express, Vol. 21, Issue 11, pp. 13279-13292 (2013) 2) D. Pliutau and N. S. Prasad, "Cross-band Relative Absorption Technique for Molecular Mixing Ratio Determination," in CLEO: 2013, OSA Technical Digest (online) (Optical Society of America, 2013), paper CW3L.4. 3) Denis Pliutau; Narasimha S. Prasad; 'Semi-empirical validation of the cross-band relative absorption technique for the measurement of molecular mixing ratios',.Proc. SPIE 8731, Laser Radar Technology and Applications XVIII, 87310L (May 20, 2013); doi:10.1117/12.2016661. 4) Denis Pliutau,; Narasimha S. Prasad; 'Comparative analysis of alternative spectral bands of CO2 and O2 for the sensing of CO2 mixing ratios' Proc. SPIE 8718, Advanced Environmental, Chemical, and Biological Sensing Technologies X, 87180L (May 31, 2013); doi:10.1117/12.2016337.

  1. Assignment and rotational analysis of new absorption bands of carbon dioxide isotopologues in Venus spectra

    NASA Astrophysics Data System (ADS)

    Robert, S.; Borkov, Yu. G.; Vander Auwera, J.; Drummond, R.; Mahieux, A.; Wilquet, V.; Vandaele, A. C.; Perevalov, V. I.; Tashkun, S. A.; Bertaux, J. L.

    2013-01-01

    We present absorption bands of carbon dioxide isotopologues, detected by the Solar Occultation for the Infrared Range (SOIR) instrument on board the Venus Express Satellite. The SOIR instrument combines an echelle spectrometer and an Acousto-Optical Tunable Filter (AOTF) for order selection. It performs solar occultation measurements in the Venus atmosphere in the IR region (2.2-4.3 μm), at a resolution of 0.12-0.18 cm-1. The wavelength range probed by SOIR allows a detailed chemical inventory of the Venus atmosphere above the cloud layer (65-150 km) to be made with emphasis on the vertical distributions of gases. Thanks to the SOIR spectral resolution, a new CO2 absorption band was identified: the 21101-01101 band of 16O12C18O with R branch up to J=31. Two other previously reported bands were observed dispelling any doubts about their identifications: the 20001-00001 band of 16O13C18O [Villanueva G, et al. J Quant Spectrosc Radiat Transfer 2008;109:883-894] and the 01111-00001 band of 16O12C18O [Villanueva G, et al. J Quant Spectrosc Radiat Transfer 2008;109:883-894 and Wilquet V, et al. J Quant Spectrosc Radiat Transfer 2008;109:895-905]. These bands were analyzed, and spectroscopic constants characterizing them were obtained. The rotational assignment of the 20001-00001 band was corrected. The present measurements are compared with data available in the HITRAN database.

  2. Impurity Sub-Band in Heavily Cu-Doped InAs Nanocrystal Quantum Dots Detected by Ultrafast Transient Absorption.

    PubMed

    Yang, Chunfan; Faust, Adam; Amit, Yorai; Gdor, Itay; Banin, Uri; Ruhman, Sanford

    2016-05-19

    The effect of Cu impurities on the absorption cross section, the rate of hot exction thermalization, and on exciton recombination processes in InAs quantum dots was studied by femtosecond transient absorption. Our findings reveal dynamic spectral effects of an emergent impurity sub-band near the bottom of the conduction band. Previously hypothesized to explain static photophysical properties of this system, its presence is shown to shorten hot carrier relaxation. Partial redistribution of interband oscillator strength to sub-band levels reduces the band edge bleach per exciton progressively with the degree of doping, even though the total linear absorption cross section at the band edge remains unchanged. In contrast, no doping effects were detected on absorption cross sections high in the conduction band, as expected due to the relatively high density of sates of the undoped QDs. PMID:26720008

  3. Rotational Profiles of Molecular Absorption Bands in Astrophysically Relevant Conditions: Ab-Initio Approach

    SciTech Connect

    Malloci, Giuliano; Mulas, Giacomo; Cappellini, Giancarlo; Satta, Guido; Porceddu, Ignazio; Benvenuti, Piero

    2004-05-01

    A theoretical study of rotational profiles of molecular absorption bands is essential for direct comparison with observations of diffuse interstellar bands. Applications using gaussian quantum-chemical approach within DFT are presented. Structural and vibrational properties of the polycyclic aromatic hydrocarbon ovalene cation (C32H14+) are obtained. We discuss the expected profile of the first electronic transition of such molecule, obtained with a Monte Carlo model of its rotation in the physical conditions of low temperatures and absence of collisions which are characteristic of the interstellar medium (ISM).

  4. An alternative model for photodynamic therapy of cancers: Hot-band absorption

    NASA Astrophysics Data System (ADS)

    Wang, Jing; Chen, Jiyao

    2013-12-01

    The sulfonated aluminum phthalocyanine (AlPcS), a photosensitizer for photodynamic cancer therapy (PDT), has an absorption tail in the near-infrared region (700-900 nm) which is so-called hot band absorption (HBA). With the HBA of 800 nm, the up-conversion excitation of AlPcS was achieved followed by the anti-Stocks emission (688 nm band) and singlet oxygen production. The HBA PDT of AlPcS seriously damaged the KB and HeLa cancer cells, with a typical light dose dependent mode. Particularly, the in vitro experiments with the AlPcS shielding solutions further showed that the HBA PDT can overcome a self-shielding effect benefiting the PDT applications.

  5. Parallel LC circuit model for multi-band absorption and preliminary design of radiative cooling.

    PubMed

    Feng, Rui; Qiu, Jun; Liu, Linhua; Ding, Weiqiang; Chen, Lixue

    2014-12-15

    We perform a comprehensive analysis of multi-band absorption by exciting magnetic polaritons in the infrared region. According to the independent properties of the magnetic polaritons, we propose a parallel inductance and capacitance(PLC) circuit model to explain and predict the multi-band resonant absorption peaks, which is fully validated by using the multi-sized structure with identical dielectric spacing layer and the multilayer structure with the same strip width. More importantly, we present the application of the PLC circuit model to preliminarily design a radiative cooling structure realized by merging several close peaks together. This omnidirectional and polarization insensitive structure is a good candidate for radiative cooling application. PMID:25607485

  6. Collisional Induced Absorption (CIA) bands measured in the IR spectral range .

    NASA Astrophysics Data System (ADS)

    Stefani, S.; Piccioni, G.; Snels, M.; Adriani, A.; Grassi, D.

    In this work we present two experimental setup able to characterize the optical properties of gases, in particular CO_2 and H_2, at typically planetary conditions. The apparatus consists of a Fourier Transform InfraRed (FT-IT) interferometer able to work in a wide spectral range, from 350 to 25000 cm-1 (0.4 to 29 mu m ) with a relatively high spectral resolution, from 10 to 0.07 cm-1. Two dedicated gas cells have been integrated with the FT-IR. The first, called High Pressure High Temperature (HP-HT), can support pressures up to 300 bar, temperatures up to 300oC and is characterized by an optical path of 2 cm. The second one, a Multi Pass (MP) absorption gas cell, is designed to have a variable optical path, from 2.5 to 30 m, can be heated up to 200o and operate at pressures up to 10 bar. In this paper, measurements of Collision-Induced Absorption (CIA) bands in carbon dioxide and hydrogen recorded in the InfraRed spectral range will be presented. In principle, linear symmetric molecules such as CO_2 and H_2 possess no dipole moment, but, even when the pressure is only a few bar, we have observed the Collisional Induced Absorption (CIA) bands. This absorption results from a short-time collisional interaction between molecules. The band integrated intensity shows a quadratic dependence versus density opposed to the absorption by isolated molecules, which follows Beer's law \\citep{Beer's}. This behaviour suggests an absorption by pairs rather than by individual molecules. The bands integrated intensities show a linear dependence vs square density according to \\citep {CIA Shape} and \\citep{CIA posi}. For what concerns the H_2 CIA bands, a preliminary comparison between simulated data obtained with the model described in \\citep{CIA H2}and measured, shows a good agreement. These processes are very relevant in the dense atmospheres of planets, such as those of Venus and Jupiter and also in extrasolar planets. A detailed knowledge of these contributions is very

  7. Nitric oxide γ band fluorescent scattering and self-absorption in the mesosphere and lower thermosphere

    NASA Astrophysics Data System (ADS)

    Stevens, Michael H.

    1995-08-01

    The fluorescent scattering of UV sunlight and self-absorption by the nitric oxide (NO) γ bands between 2000-2500 Å are quantified for the purpose of inferring NO density profiles as a function of altitude in the mesosphere and above. Rotational line emission rate factors and cross sections are calculated at a variety of temperatures. The observed variation of the solar spectrum across the γ bands and its effect on emission rate factors are explored by using irradiance measurements that resolve features down to 0.1 Å. The model also includes quenching by O2 and N2, multiple scattering, temperature effects, attenuation of the solar irradiance by O2 and ozone, and self-absorption with the summation of adjacent rotational features. Results indicate that for resonant γ bands, the rotational structure in emission is not symmetric to that in absorption so that as self-absorption increases the shape of the observed emission envelope changes. For γ(1,0) this is largely characterized by an increase in the integrated emission observed longward of 2151 Å compared to shortward. It is found that solar irradiances measured at 0.1 Å resolution decrease the calculated γ(1,0) and γ(0,0) band emission rate factors by less than 3% compared to those measured at 2 Å resolution. However, more Fraunhofer structure included in the calculation is reflected in the relative intensities of the rotational features. It is also found that extinction of the solar irradiance by ozone and quenching by O2 rapidly reduce the γ(1,0) emission rate factor with decreasing altitude below 60 km.

  8. Analysis of the 4800-Å absorption band of Cs 2 by the classical method

    NASA Astrophysics Data System (ADS)

    Tellinghuisen, Joel; Moeller, Michael B.

    1980-09-01

    The broad absorption band in Cs 2 having peak intensity near 4800 Å is analyzed through computational simulation of the experimental spectrum using the classical method. The absorption, which terminates in a weak satellite at 5223 Å, can be interpreted in terms of a single transition from the ground state ( Re = 4.65 Å, ω e = 42 cm -1) to an upper state having Te = 20 470 cm -1, ω e = 33 cm -1 and Re = 5.28 Å. The absolute absorption strength is roughly consistent with published lifetime data, but its reliability is limited by thermodynamic uncertainties stemming from the remaining uncertainty in the Cs 2 ground state dissociation enegy. The paper includes a summary of diatomic radiation relations pertinent to the analysis of low-resolution spectra, and a brief discussion of the reduced potential method applied to the alkali dimer ground states.

  9. Decomposing the First Absorption Band of OCS Using Photofragment Excitation Spectroscopy.

    PubMed

    Toulson, Benjamin W; Murray, Craig

    2016-09-01

    Photofragment excitation spectra of carbonyl sulfide (OCS) have been recorded from 212-260 nm by state-selectively probing either electronically excited S((1)D) or ground state S((3)P) photolysis products via 2 + 1 resonance-enhanced multiphoton ionization. Probing the major S((1)D) product results in a broad, unstructured action spectrum that reproduces the overall shape of the first absorption band. In contrast, spectra obtained probing S((3)P) products display prominent resonances superimposed on a broad continuum; the resonances correspond to the diffuse vibrational structure observed in the conventional absorption spectrum. The vibrational structure is assigned to four progressions, each dominated by the C-S stretch, ν1, following direct excitation to quasi-bound singlet and triplet states. The S((3)PJ) products are formed with a near-statistical population distribution over the J = 2, 1, and 0 spin-orbit levels across the wavelength range investigated. Although a minor contributor to the S atom yield near the peak of the absorption cross section, the relative yield of S((3)P) increases significantly at longer wavelengths. The experimental measurements validate recent theoretical work characterizing the electronic states responsible for the first absorption band by Schmidt and co-workers. PMID:27552402

  10. Sensitivity analysis of oxygen absorption lines in the 1.26-1.27 micron spectral band

    NASA Astrophysics Data System (ADS)

    Edwards, W. C.; Prasad, N.; Browell, E. V.

    2009-12-01

    In the Decadal Survey prepared by the National Research Council (Reference: Earth Science and Applications from Space: National Imperatives for the Next Decade and Beyond), the ASCENDS mission (Active Sensing of CO2 Emissions over Nights, Days and Seasons), requires simultaneous laser remote sensing of CO2 and O2 in order to convert CO2 atmospheric concentrations to mixing ratios. As the mission is envisioned, the CO2 mixing ratio needs to be measured to a precision of 0.5 percent of background or better (slightly less than 2 ppm) at 100-km horizontal length scale overland and at 200-km scale over open oceans. While the O2 measurement could be made at 0.765 µm (the oxygen A band), the absorption cross section is substantially higher and the scattering is lower in the 1.26-1.27 µm wavelength band, and as such it is anticipated that better accuracies could be accomplished. Hence, NASA Langley Research Center is developing oxygen lidar technology in the 1.26-1.27 micron band for surface pressure measurements. One or more wavelengths for differential absorption lidar operation have to be carefully chosen to eliminate ambient influences on them. The model optical depth calculation is very sensitive to knowledge of the transmitted wavelengths and to the choice of Voigt input parameters. Uncertainties in atmospheric profiles of temperature, pressure and relative humidity can cause ~0.5 % errors in model optical depths. In order to select candidate wavelengths in the 1.26 micron spectral band, wavelength uncertainties due to temperature and pressure have to be determined. Uncertainties at line center and offset wavelengths have to be known precisely to reduce uncertainties in oxygen concentration measurements from airborne and space based platforms. In this paper, based on HITRAN database and absorption line measurements, we evaluate systematic relative errors and their sources of pressure shift and atmospheric temperature influences for selected O2 lines suitable for

  11. Electronic absorption band broadening and surface roughening of phthalocyanine double layers by saturated solvent vapor treatment

    SciTech Connect

    Kim, Jinhyun; Yim, Sanggyu

    2012-10-15

    Variations in the electronic absorption (EA) and surface morphology of three types of phthalocyanine (Pc) thin film systems, i.e. copper phthalocyanine (CuPc) single layer, zinc phthalocyanine (ZnPc) single layer, and ZnPc on CuPc (CuPc/ZnPc) double layer film, treated with saturated acetone vapor were investigated. For the treated CuPc single layer film, the surface roughness slightly increased and bundles of nanorods were formed, while the EA varied little. In contrast, for the ZnPc single layer film, the relatively high solubility of ZnPc led to a considerable shift in the absorption bands as well as a large increase in the surface roughness and formation of long and wide nano-beams, indicating a part of the ZnPc molecules dissolved in acetone, which altered their molecular stacking. For the CuPc/ZnPc film, the saturated acetone vapor treatment resulted in morphological changes in mainly the upper ZnPc layer due to the significantly low solubility of the underlying CuPc layer. The treatment also broadened the EA band, which involved a combination of unchanged CuPc and changed ZnPc absorption.

  12. Imaging Breathing Rate in the CO2Absorption Band.

    PubMed

    Fei, Jin; Zhu, Zhen; Pavlidis, Ioannis

    2005-01-01

    Following up on our previous work, we have developed one more non-contact method to measure human breathing rate. We have retrofitted our Mid-Wave Infra-Red (MWIR) imaging system with a narrow band-pass filter in the CO2absorption band (4.3 µm). This improves the contrast between the foreground (i.e., expired air) and background (e.g., wall). Based on the radiation information within the breath flow region, we get the mean dynamic thermal signal. This signal is quasi-periodic due to the interleaving of high and low intensities corresponding to expirations and inspirations respectively. We sample the signal at a constant rate and then determine the breathing frequency through Fourier analysis. We have performed experiments on 9 subjects at distances ranging from 6-8 ft. We compared the breathing rate computed by our novel method with ground-truth measurements obtained via a traditional contact device (PowerLab/4SP from ADInstruments with an abdominal transducer). The results show high correlation between the two modalities. For the first time, we report a Fourier based breathing rate computation method on a MWIR signal in the CO2absorption band. The method opens the way for desktop, unobtrusive monitoring of an important vital sign, that is, breathing rate. It may find widespread applications in preventive medicine as well as sustained physiological monitoring of subjects suffering from chronic ailments. PMID:17282279

  13. Understanding of sub-band gap absorption of femtosecond-laser sulfur hyperdoped silicon using synchrotron-based techniques

    PubMed Central

    Limaye, Mukta V.; Chen, S. C.; Lee, C. Y.; Chen, L. Y.; Singh, Shashi B.; Shao, Y. C.; Wang, Y. F.; Hsieh, S. H.; Hsueh, H. C.; Chiou, J. W.; Chen, C. H.; Jang, L. Y.; Cheng, C. L.; Pong, W. F.; Hu, Y. F.

    2015-01-01

    The correlation between sub-band gap absorption and the chemical states and electronic and atomic structures of S-hyperdoped Si have been extensively studied, using synchrotron-based x-ray photoelectron spectroscopy (XPS), x-ray absorption near-edge spectroscopy (XANES), extended x-ray absorption fine structure (EXAFS), valence-band photoemission spectroscopy (VB-PES) and first-principles calculation. S 2p XPS spectra reveal that the S-hyperdoped Si with the greatest (~87%) sub-band gap absorption contains the highest concentration of S2− (monosulfide) species. Annealing S-hyperdoped Si reduces the sub-band gap absorptance and the concentration of S2− species, but significantly increases the concentration of larger S clusters [polysulfides (Sn2−, n > 2)]. The Si K-edge XANES spectra show that S hyperdoping in Si increases (decreased) the occupied (unoccupied) electronic density of states at/above the conduction-band-minimum. VB-PES spectra evidently reveal that the S-dopants not only form an impurity band deep within the band gap, giving rise to the sub-band gap absorption, but also cause the insulator-to-metal transition in S-hyperdoped Si samples. Based on the experimental results and the calculations by density functional theory, the chemical state of the S species and the formation of the S-dopant states in the band gap of Si are critical in determining the sub-band gap absorptance of hyperdoped Si samples. PMID:26098075

  14. Infrared absorption band in deformed qtz crystals analyzed by combining different microstructural methods

    NASA Astrophysics Data System (ADS)

    Stunitz, Holger; Thust, Anja; Behrens, Harald; Heilbronner, Renee; Kilian, Ruediger

    2016-04-01

    Natural single crystals of quartz have been experimentally deformed in two orientations: (1) normal to one prism-plane, (2) In O+ orientation at temperatures of 900 and 1000°C, pressures of 1.0 and 1.5 GPa, and strain rates of ~1 x 10-6s-1. The starting material is milky quartz, consisting of dry quartz (H2O contents of <150 H/106Si) with fluid inclusions (FI). During pressurization many FÍs decrepitate. Cracks heal and small neonate FÍs form, increasing the number of FÍs drastically. During subsequent deformation, the size of FÍs is further reduced (down to ~10 nm). Sample deformation occurs by dominant dislocation glide on selected slip systems, accompanied by some dynamic recovery. Strongly deformed regions show FTIR spectra with a pointed broad absorption band in the ~3400 cm-1 region as a superposition of molecular H2O bands and three discrete absorption bands (at 3367, 3400, and 3434 cm-1). In addition, there is a discrete absorption band at 3585 cm-1, which only occurs in deformed regions. The 3585 cm-1 band is reduced or even disappears after annealing. This band is polarized and represents structurally bound H, its H-content is estimated to be 1-3% of the total H2O-content and appears to be associated with dislocations. The H2O weakening effect in our FI-bearing natural quartz crystals is assigned to the processes of dislocation generation and multiplication at small FÍs. The deformation processes in these crystals represent a recycling of H2O between FÍs, dislocation generation at very small fluid inclusions, incorporation of structurally bound H into dislocation cores, and release of H2O from dislocations back into FÍs during recovery. Cracking and crack healing play an important role in the recycling process and imply a close interrelationship between brittle and crystal plastic deformation. The H2O weakening by this process is of a disequilibrium nature and thus depends on the amount of H2O available.

  15. Concentration measurement of NO using self-absorption spectroscopy of the γ band system in a pulsed corona discharge.

    PubMed

    Zhai, Xiaodong; Ding, Yanjun; Peng, Zhimin; Luo, Rui

    2012-07-10

    Nitric oxide (NO) concentrations were measured using the γ band system spectrum based on the strong self-absorption effect of NO in pulsed corona discharges. The radiative transitional intensities of the NO γ band were simulated based on the theory of molecular spectroscopy. The intensities of some bands, especially γ(0,0) and γ(1,0), are weakened by the self-absorption. The correlations between the spectral self-absorption intensities and NO concentration were validated using a modified Beer-Lambert law with a combined factor K relating the branching ratio and the NO concentration, and a nonlinear index α that is applicable to the broadband system. Optical emissive spectra in pulsed corona discharges in NO and N2/He mixtures were used to evaluate the two parameters for various conditions. Good agreement between the experimental and theoretical results verifies the self-absorption behavior seen in the UV spectra of the NO γ bands. PMID:22781235

  16. Origin of the red shifts in the optical absorption bands of nonplanar tetraalkylporphyrins.

    PubMed

    Haddad, Raid E; Gazeau, Stéphanie; Pécaut, Jacques; Marchon, Jean-Claude; Medforth, Craig J; Shelnutt, John A

    2003-02-01

    The view that the large red shifts seen in the UV-visible absorption bands of peripherally crowded nonplanar porphyrins are the result of nonplanar deformations of the macrocycle has recently been challenged by the suggestion that the red shifts arise from substituent-induced changes in the macrocycle bond lengths and bond angles, termed in-plane nuclear reorganization (IPNR). We have analyzed the contributions to the UV-visible band shifts in a series of nickel or zinc meso-tetraalkylporphyrins to establish the origins of the red shifts in these ruffled porphyrins. Structures were obtained using a molecular mechanics force field optimized for porphyrins, and the nonplanar deformations were quantified by using normal-coordinate structural decomposition (NSD). Transition energies were calculated by the INDO/S semiempirical method. These computational studies demonstrate conclusively that the large Soret band red shifts ( approximately 40 nm) seen for very nonplanar meso-tetra(tert-butyl)porphyrin compared to meso-tetra(methyl)porphyrin are primarily the result of nonplanar deformations and not IPNR. Strikingly, nonplanar deformations along the high-frequency 2B(1u) and 3B(1u) normal coordinates of the macrocycle are shown to contribute significantly to the observed red shifts, even though these deformations are an order of magnitude smaller than the observed ruffling (1B(1u)) deformation. Other structural and electronic influences on the UV-visible band shifts are discussed and problems with the recent studies are examined (e.g., the systematic underestimation of the 2B(1u) and 3B(1u) modes in artificially constrained porphyrin structures that leads to a mistaken attribution of the red shift to IPNR). The effect of nonplanar deformations on the UV-visible absorption bands is then probed experimentally with a series of novel bridled nickel chiroporphyrins. In these compounds, the substituent effect is essentially invariant and the amount of nonplanar deformation

  17. Ultra-narrow band perfect absorbers based on plasmonic analog of electromagnetically induced absorption.

    PubMed

    He, Jinna; Ding, Pei; Wang, Junqiao; Fan, Chunzhen; Liang, Erjun

    2015-03-01

    A novel plasmonic metamaterial consisting of the solid (bar) and the inverse (slot) compound metallic nanostructure for electromagnetically induced absorption (EIA) is proposed in this paper, which is demonstrated to achieve an ultra-narrow absorption peak with the linewidth less than 8 nm and the absorptivity exceeding 97% at optical frequencies. This is attributed to the plasmonic EIA resonance arising from the efficient coupling between the magnetic response of the slot (dark mode) and the electric resonance of the bar (bright mode). To the best of our knowledge, this is the first time that the plasmonic EIA is used to realize the narrow-band perfect absorbers. The underlying physics are revealed by applying the two-coupled-oscillator model. The near-perfect-absorption resonance also causes an enhancement of about 50 times in H-field and about 130 times in E-field within the slots. Such absorber possesses potential for applications in filter, thermal emitter, surface enhanced Raman scattering, sensing and nonlinear optics. PMID:25836832

  18. Collisional Induced Absorption (CIA) bands of CO2 and H2 measured in the IR spectral range

    NASA Astrophysics Data System (ADS)

    Stefani, S.; Piccioni, G.; Snels, M.; Adriani, A.; Grassi, D.

    2015-10-01

    In this paper we present the results on the Collisional Induced Absorption (CIA) bands of CO2 and H2 measured employing two different experimental setup. Each of them allows us to reproduce typical planetary conditions, at a pressure and temperature from 1 up to 50 bar and from 298 up to 500 K respectively. A detailed study on the temperature dependence of the CO2 CIA absorption bands will be presented.

  19. Theoretical reproduction of the Q-band absorption spectrum of free-base chlorin

    NASA Astrophysics Data System (ADS)

    Wójcik, Justyna; Ratuszna, Alicja; Peszke, Jerzy; Wrzalik, Roman

    2015-01-01

    The computational results of the features observed in the room-temperature Q-band absorption spectrum of free-base chlorin (H2Ch) are presented. The vibrational structures of the first and second excited singlet states were calculated based on a harmonic approximation using density functional theory and its time dependent extension within the Franck-Condon and Herzberg-Teller approaches. The outcome allowed to identify the experimental bands and to assign them to the specific vibrational transitions. A very good agreement between the simulated and measured wavelengths and their relative intensities provided the opportunity to predict the origin of the S0 → S2 transition which could not be determined experimentally.

  20. Theoretical reproduction of the Q-band absorption spectrum of free-base chlorin.

    PubMed

    Wójcik, Justyna; Ratuszna, Alicja; Peszke, Jerzy; Wrzalik, Roman

    2015-01-21

    The computational results of the features observed in the room-temperature Q-band absorption spectrum of free-base chlorin (H2Ch) are presented. The vibrational structures of the first and second excited singlet states were calculated based on a harmonic approximation using density functional theory and its time dependent extension within the Franck-Condon and Herzberg-Teller approaches. The outcome allowed to identify the experimental bands and to assign them to the specific vibrational transitions. A very good agreement between the simulated and measured wavelengths and their relative intensities provided the opportunity to predict the origin of the S0 → S2 transition which could not be determined experimentally. PMID:25612704

  1. Study of sub band gap absorption of Sn doped CdSe thin films

    NASA Astrophysics Data System (ADS)

    Kaur, Jagdish; Rani, Mamta; Tripathi, S. K.

    2014-04-01

    The nanocrystalline thin films of Sn doped CdSe at different dopants concentration are prepared by thermal evaporation technique on glass substrate at room temperature. The effect of Sn doping on the optical properties of CdSe has been studied. A decrease in band gap value is observed with increase in Sn concentration. Constant photocurrent method (CPM) is used to study the absorption coefficient in the sub band gap region. Urbach energy has been obtained from CPM spectra which are found to increase with amount of Sn dopants. The refractive index data calculated from transmittance is used for the identification of oscillator strength and oscillator energy using single oscillator model which is found to be 7.7 and 2.12 eV, 6.7 and 2.5 eV for CdSe:Sn 1% and CdSe:Sn 5% respectively.

  2. Study of sub band gap absorption of Sn doped CdSe thin films

    SciTech Connect

    Kaur, Jagdish; Rani, Mamta; Tripathi, S. K.

    2014-04-24

    The nanocrystalline thin films of Sn doped CdSe at different dopants concentration are prepared by thermal evaporation technique on glass substrate at room temperature. The effect of Sn doping on the optical properties of CdSe has been studied. A decrease in band gap value is observed with increase in Sn concentration. Constant photocurrent method (CPM) is used to study the absorption coefficient in the sub band gap region. Urbach energy has been obtained from CPM spectra which are found to increase with amount of Sn dopants. The refractive index data calculated from transmittance is used for the identification of oscillator strength and oscillator energy using single oscillator model which is found to be 7.7 and 2.12 eV, 6.7 and 2.5 eV for CdSe:Sn 1% and CdSe:Sn 5% respectively.

  3. Theoretical modeling of low-energy electronic absorption bands in reduced cobaloximes

    DOE PAGESBeta

    Bhattacharjee, Anirban; Chavarot-Kerlidou, Murielle; Dempsey, Jillian L.; Gray, Harry B.; Fujita, Etsuko; Muckerman, James T.; Fontecave, Marc; Artero, Vincent; Arantes, Guilherme M.; Field, Martin J.

    2014-08-11

    Here, we report that the reduced Co(I) states of cobaloximes are powerful nucleophiles that play an important role in the hydrogen-evolving catalytic activity of these species. In this work we have analyzed the low energy electronic absorption bands of two cobaloxime systems experimentally and using a variety of density functional theory and molecular orbital ab initio quantum chemical approaches. Overall we find a reasonable qualitative understanding of the electronic excitation spectra of these compounds but show that obtaining quantitative results remains a challenging task.

  4. Thermochromic Absorption, Fluorescence Band Shifts and Dipole Moments of BADAN and ACRYLODAN

    NASA Astrophysics Data System (ADS)

    Kawski, A.; Kukliński, B.; Bojarski, P.

    2002-08-01

    Using the thermochromic shift method of absorption and fluorescence bands, the electric dipole moments in the ground (μg) and excited (μe) state are simultaneously determined for BADAN (6-bromoacetyl-2-dimethylamino-naphtalene) and ACRYLODAN (6-acrylolyl-2-dimethylamino-naphtalene) in ethyl acetate. For these compounds the same ratio μe/μg = 2.9 was found, which is similar to that of PRODAN (6-propionyl-2-dimethylamino-naphtalene). The estimated empirical Onsager radii afor BADAN and ACRYLODAN are the same, and they are somewhat smaller than the calculated geometrical values.

  5. Theoretical modeling of low-energy electronic absorption bands in reduced cobaloximes

    SciTech Connect

    Bhattacharjee, Anirban; Chavarot-Kerlidou, Murielle; Dempsey, Jillian L.; Gray, Harry B.; Fujita, Etsuko; Muckerman, James T.; Fontecave, Marc; Artero, Vincent; Arantes, Guilherme M.; Field, Martin J.

    2014-08-11

    Here, we report that the reduced Co(I) states of cobaloximes are powerful nucleophiles that play an important role in the hydrogen-evolving catalytic activity of these species. In this work we have analyzed the low energy electronic absorption bands of two cobaloxime systems experimentally and using a variety of density functional theory and molecular orbital ab initio quantum chemical approaches. Overall we find a reasonable qualitative understanding of the electronic excitation spectra of these compounds but show that obtaining quantitative results remains a challenging task.

  6. Theoretical Modeling of Low Energy Electronic Absorption Bands in Reduced Cobaloximes

    PubMed Central

    Bhattacharjee, Anirban; Chavarot-Kerlidou, Murielle; Dempsey, Jillian L.; Gray, Harry B.; Fujita, Etsuko; Muckerman, James T.; Fontecave, Marc; Artero, Vincent; Arantes, Guilherme M.; Field, Martin J.

    2015-01-01

    The reduced Co(I) states of cobaloximes are powerful nucleophiles that play an important role in the hydrogen-evolving catalytic activity of these species. In this work we have analyzed the low energy electronic absorption bands of two cobaloxime systems experimentally and using a variety of density functional theory and molecular orbital ab initio quantum chemical approaches. Overall we find a reasonable qualitative understanding of the electronic excitation spectra of these compounds but show that obtaining quantitative results remains a challenging task. PMID:25113847

  7. Femtosecond supercontinuum generation in water in the vicinity of absorption bands.

    PubMed

    Dharmadhikari, J A; Steinmeyer, G; Gopakumar, G; Mathur, D; Dharmadhikari, A K

    2016-08-01

    We show that it is possible to overcome the perceived limitations caused by absorption bands in water so as to generate supercontinuum (SC) spectra in the anomalous dispersion regime that extend well beyond 2000 nm wavelength. By choosing a pump wavelength within a few hundred nanometers above the zero-dispersion wavelength of 1048 nm, initial spectral broadening extends into the normal dispersion regime and, in turn, the SC process in the visible strongly benefits from phase-matching and matching group velocities between dispersive radiation and light in the anomalous dispersion regime. Some of the SC spectra are shown to encompass two and a half octaves. PMID:27472597

  8. Linear-Circular Dichroism of Four-Photon Absorption of Light in Semiconductors with a Complex Valence Band

    NASA Astrophysics Data System (ADS)

    Rasulov, R. Ya.; Rasulov, V. R.; Eshboltaev, I.

    2016-04-01

    Matrix elements of optical transitions occuring between the subbands of the valence band of a p-GaAs type semiconductor are calculated. Transitions associated with the non-simultaneous absorption of single photons and simultaneous absorption of two photons are taken into account. The expressions are obtained for the average values of the square modulus of matrix elements calculated with respect to the solid angle of the wave vector of holes. Linear-circular dichroism of four-photon absorption of light in semiconductors with a complex valence band is theoretically studied.

  9. Absorption coefficients for the 6190-A CH4 band between 290 and 100 K with application to Uranus' atmosphere

    NASA Technical Reports Server (NTRS)

    Smith, Wm. Hayden; Conner, Charles P.; Baines, Kevin H.

    1990-01-01

    A novel laser intracavity photoacoustic spectroscopy method allowing high sample control accuracy due to the small sample volume required has been used to obtain absorption coefficients for the CH4 6190 A band as a function of temperature, from 290 to 100 K. The peak absorption coefficient is found to increase from 0.6 to 1.0/cm, and to be accompanied by significant band shape changes. When used to further constrain the Baines and Bergstrahl (1986) standard model of the Uranus atmosphere, the low-temperature data yield an excellent fit to the bandshape near the 6190 A band's minimum.

  10. Nanosecond light induced, thermally tunable transient dual absorption bands in a-Ge₅As₃₀Se₆₅ thin film.

    PubMed

    Khan, Pritam; Saxena, Tarun; Jain, H; Adarsh, K V

    2014-01-01

    In this article, we report the first observation of nanosecond laser induced transient dual absorption bands, one in the bandgap (TA₁) and another in the sub-bandgap (TA₂) regions of a-Ge₅As₃₀Se₆₅ thin films. Strikingly, these bands are thermally tunable and exhibit a unique contrasting characteristic: the magnitude of TA₁ decreases while that of TA₂ increases with increasing temperature. Further, the decay kinetics of these bands is strongly influenced by the temperature, which signifies a strong temperature dependent exciton recombination mechanism. The induced absorption shows quadratic and the decay time constant shows linear dependence on the laser beam fluence. PMID:25300520

  11. Absorption coefficients for the 6190-A CH sub 4 band between 290 and 100 K with application to Uranus' atmosphere

    SciTech Connect

    Smith, WM.H.; Conner, C.P.; Baines, K.H. JPL, Pasadena, CA )

    1990-05-01

    A novel laser intracavity photoacoustic spectroscopy method allowing high sample control accuracy due to the small sample volume required has been used to obtain absorption coefficients for the CH{sub 4} 6190 A band as a function of temperature, from 290 to 100 K. The peak absorption coefficient is found to increase from 0.6 to 1.0/cm, and to be accompanied by significant band shape changes. When used to further constrain the Baines and Bergstrahl (1986) standard model of the Uranus atmosphere, the low-temperature data yield an excellent fit to the bandshape near the 6190 A band's minimum. 18 refs.

  12. Shallow electron traps in alkali halide crystals: Mollwo-Ivey relations of the optical absorption bands

    NASA Astrophysics Data System (ADS)

    Ziraps, Valters

    2001-03-01

    Evidences are given that two classes of the transient IR- absorption bands: (a) with max. at 0.27-0.36 eV in NaCl, KCl, KBr, KI and RbCl (due to shallow electron traps according G. Jacobs or due to bound polarons according E.V. Korovkin and T.A. Lebedkina) and (b) with max. at 0.15-0.36 eV in NaI, NaBr, NaCl:I, KCl:I, RbCl:I and RbBr:I (due to on-center STE localized at iodine dimer according M. Hirai and collaborators) are caused by the same defect- atomic alkali impurity center [M+]c0e- (electron e- trapped by a substitutional smaller size alkali cation impurity [M+]c0). The Mollwo-Ivey plots (for the transient IR-absorption bands) of the zero-phonon line energy E0 (for NaCl, KCl, KBr, RbCl and NaBr, KCl:I) and/or the low-energy edge valued E0 (for NaI, RbCl:I, RbBr:I) versus anion-cation distance (d) evidence that two types of the [M+]c0e- centers are predominant: (a) [Na+]c0e- in the KX and RbX host crystals with the relation E0approximately equals 6.15/d2.74, (b) [Li+]c03- in the NaX host crystals - E0approximately equals 29.4/d4.72. The Mollwo-Ivey relation E0approximately equals 18.36/d(superscript 2.70 is fulfilled as well for the F' band in NaCl, KCl, KBr, KI, RbCl, RbI if we use the F' center optical binding energy values E0.

  13. Ultra-wideband microwave absorber by connecting multiple absorption bands of two different-sized hyperbolic metamaterial waveguide arrays

    PubMed Central

    Yin, Xiang; Long, Chang; Li, Junhao; Zhu, Hua; Chen, Lin; Guan, Jianguo; Li, Xun

    2015-01-01

    Microwave absorbers have important applications in various areas including stealth, camouflage, and antenna. Here, we have designed an ultra-broadband light absorber by integrating two different-sized tapered hyperbolic metamaterial (HMM) waveguides, each of which has wide but different absorption bands due to broadband slow-light response, into a unit cell. Both the numerical and experimental results demonstrate that in such a design strategy, the low absorption bands between high absorption bands with a single-sized tapered HMM waveguide array can be effectively eliminated, resulting in a largely expanded absorption bandwidth ranging from 2.3 to 40 GHz. The presented ultra-broadband light absorber is also insensitive to polarization and robust against incident angle. Our results offer a further step in developing practical artificial electromagnetic absorbers, which will impact a broad range of applications at microwave frequencies. PMID:26477740

  14. Ultra-wideband microwave absorber by connecting multiple absorption bands of two different-sized hyperbolic metamaterial waveguide arrays

    NASA Astrophysics Data System (ADS)

    Yin, Xiang; Long, Chang; Li, Junhao; Zhu, Hua; Chen, Lin; Guan, Jianguo; Li, Xun

    2015-10-01

    Microwave absorbers have important applications in various areas including stealth, camouflage, and antenna. Here, we have designed an ultra-broadband light absorber by integrating two different-sized tapered hyperbolic metamaterial (HMM) waveguides, each of which has wide but different absorption bands due to broadband slow-light response, into a unit cell. Both the numerical and experimental results demonstrate that in such a design strategy, the low absorption bands between high absorption bands with a single-sized tapered HMM waveguide array can be effectively eliminated, resulting in a largely expanded absorption bandwidth ranging from 2.3 to 40 GHz. The presented ultra-broadband light absorber is also insensitive to polarization and robust against incident angle. Our results offer a further step in developing practical artificial electromagnetic absorbers, which will impact a broad range of applications at microwave frequencies.

  15. Ultra-wideband microwave absorber by connecting multiple absorption bands of two different-sized hyperbolic metamaterial waveguide arrays.

    PubMed

    Yin, Xiang; Long, Chang; Li, Junhao; Zhu, Hua; Chen, Lin; Guan, Jianguo; Li, Xun

    2015-01-01

    Microwave absorbers have important applications in various areas including stealth, camouflage, and antenna. Here, we have designed an ultra-broadband light absorber by integrating two different-sized tapered hyperbolic metamaterial (HMM) waveguides, each of which has wide but different absorption bands due to broadband slow-light response, into a unit cell. Both the numerical and experimental results demonstrate that in such a design strategy, the low absorption bands between high absorption bands with a single-sized tapered HMM waveguide array can be effectively eliminated, resulting in a largely expanded absorption bandwidth ranging from 2.3 to 40 GHz. The presented ultra-broadband light absorber is also insensitive to polarization and robust against incident angle. Our results offer a further step in developing practical artificial electromagnetic absorbers, which will impact a broad range of applications at microwave frequencies. PMID:26477740

  16. Thermally induced effect on sub-band gap absorption in Ag doped CdSe thin films

    NASA Astrophysics Data System (ADS)

    Kaur, Jagdish; Sharma, Kriti; Bharti, Shivani; Tripathi, S. K.

    2015-05-01

    Thin films of Ag doped CdSe have been prepared by thermal evaporation using inert gas condensation (IGC) method taking Argon as inert gas. The prepared thin films are annealed at 363 K for one hour. The sub-band gap absorption spectra in the as deposited and annealed thin films have been studied using constant photocurrent method (CPM). The absorption coefficient in the sub-band gap region is described by an Urbach tail in both as deposited and annealed thin films. The value of Urbach energy and number density of trap states have been calculated from the absorption coefficient in the sub-band gap region which have been found to increase after annealing treatment indicating increase in disorderness in the lattice. The energy distribution of the occupied density of states below Fermi level has also been studied using derivative procedure of absorption coefficient.

  17. Total ozone and aerosol optical depths inferred from radiometric measurements in the Chappuis absorption band

    SciTech Connect

    Flittner, D.E.; Herman, B.M.; Thome, K.J.; Simpson, J.M.; Reagan, J.A. )

    1993-04-15

    A second-derivative smoothing technique, commonly used in inversion work, is applied to the problem of inferring total columnar ozone amounts and aerosol optical depths. The application is unique in that the unknowns (i.e., total columnar ozone and aerosol optical depth) may be solved for directly without employing standard inversion methods. It is shown, however, that by employing inversion constraints, better solutions are normally obtained. The current method requires radiometric measurements of total optical depth through the Chappuis ozone band. It assumes no a priori shape for the aerosol optical depth versus wavelength profile and makes no assumptions about the ozone amount. Thus, the method is quite versatile and able to deal with varying total ozone and various aerosol size distributions. The technique is applied first in simulation, then to 119 days of measurements taken in Tucson, Arizona, that are compared to TOMS values for the same dates. The technique is also applied to two measurements taken at Mauna Loa, Hawaii, for which Dobson ozone values are available in addition to the TOMS values, and the results agree to within 15%. It is also shown through simulations that additional information can be obtained from measurements outside the Chappuis band. This approach reduces the bias and spread of the estimates total ozone and is unique in that it uses measurements from both the Chappuis and Huggins absorption bands. 12 refs., 6 figs., 2 tabs.

  18. Polarization-adjustable dual-band absorption in GHz-band metamaterial, based-on no-smoking symbol

    NASA Astrophysics Data System (ADS)

    Yoo, Young Joon; Kim, Young Ju; Lee, YoungPak; Lee, Myung Whan; Lee, Tae Gyun; Kim, Min Woo; Park, Jae Hyun

    2015-11-01

    We propose three kinds of the perfect metamaterial absorbers based on the well-known no-smoking symbol, which can adjust the absorption according to the polarization of incident electromagnetic wave. By modifying no-smoking symbol, a resonance absorption peak at 6.75 GHz can be controlled. In addition, a split-ring structure and the no-smoking symbol also adjust the absorption. We also demonstrate the absorption mechanism for all the structures. These results can be used in controlling absorption by the electromagnetic-wave detector.

  19. ESA plans new missions

    NASA Astrophysics Data System (ADS)

    Pedersen, Arne

    The tragic explosion of the space shuttle Challenger has caused a delay of at least 13 months to the European Space Agency/National Aeronautics and Space Administration (ESA/NASA) cooperative mission Ulysses, previously known as the Solar Polar Mission. Ulysses was scheduled for launch in May 1986. The launch of the Hubble Space Telescope, in which ESA is a cooperative partner, is certain to be delayed beyond the October 1986 launch date.As Eos went to press, the Giotto spacecraft, which has been on its way to Comet Halley since July 1985, was performing well, according to ESA. All investigator groups participated in operation rehearsals at the European Space Operations Centre in Darmstadt, Federal Republic of Germany, in preparation for the cometary encounter, which occurred near midnight (UT) on March 13, 1986.

  20. Anomalously Broad Diffuse Interstellar Bands and Excited CH+ Absorption in the Spectrum of Herschel 36

    NASA Astrophysics Data System (ADS)

    York, D. G.; Dahlstrom, J.; Welty, D. E.; Oka, T.; Hobbs, L. M.; Johnson, S.; Friedman, S. D.; Jiang, Z.; Rachford, B. L.; Snow, T. P.; Sherman, R.; Sonnentrucker, P.

    2014-02-01

    Anomalously broad diffuse interstellar bands (DIBs) at 5780.5, 5797.1, 6196.0, and 6613.6 Å are found in absorption along the line of sight to Herschel 36, an O star system next to the bright Hourglass nebula of the Hii region Messier 8. Excited lines of CH and CH+ are seen as well. We show that the region is very compact and itemize other anomalies of the gas. An infrared-bright star within 400 AU is noted. The combination of these effects produces anomalous DIBs, interpreted by Oka et al. (2013, see also this volume) as being caused predominantly by infrared pumping of rotational levels of relatively small molecules.

  1. VARIABILITY OF WATER AND OXYGEN ABSORPTION BANDS IN THE DISK-INTEGRATED SPECTRA OF EARTH

    SciTech Connect

    Fujii, Yuka; Suto, Yasushi; Turner, Edwin L.

    2013-03-10

    We study the variability of major atmospheric absorption features in the disk-integrated spectra of Earth with future application to Earth-analogs in mind, concentrating on the diurnal timescale. We first analyze observations of Earth provided by the EPOXI mission, and find 5%-20% fractional variation of the absorption depths of H{sub 2}O and O{sub 2} bands, two molecules that have major signatures in the observed range. From a correlation analysis with the cloud map data from the Earth Observing Satellite (EOS), we find that their variation pattern is primarily due to the uneven cloud cover distribution. In order to account for the observed variation quantitatively, we consider a simple opaque cloud model, which assumes that the clouds totally block the spectral influence of the atmosphere below the cloud layer, equivalent to assuming that the incident light is completely scattered at the cloud top level. The model is reasonably successful, and reproduces the EPOXI data from the pixel-level EOS cloud/water vapor data. A difference in the diurnal variability patterns of H{sub 2}O and O{sub 2} bands is ascribed to the differing vertical and horizontal distribution of those molecular species in the atmosphere. On Earth, the inhomogeneous distribution of atmospheric water vapor is due to the existence of its exchange with liquid and solid phases of H{sub 2}O on the planet's surface on a timescale short compared with atmospheric mixing times. If such differences in variability patterns were detected in spectra of Earth-analogs, it would provide the information on the inhomogeneous composition of their atmospheres.

  2. Investigation of band gap narrowing in nitrogen-doped La2Ti2O7 with transient absorption spectroscopy.

    PubMed

    Yost, Brandon T; Cushing, Scott K; Meng, Fanke; Bright, Joeseph; Bas, Derek A; Wu, Nianqiang; Bristow, Alan D

    2015-12-14

    Doping a semiconductor can extend the light absorption range, however, it usually introduces mid-gap states, reducing the charge carrier lifetime. This report shows that doping lanthanum dititinate (La2Ti2O7) with nitrogen extends the valence band edge by creating a continuum of dopant states, increasing the light absorption edge from 380 nm to 550 nm without adding mid-gap states. The dopant states are experimentally resolved in the excited state by correlating transient absorption spectroscopy with a supercontinuum probe and DFT prediction. The lack of mid-gap states is further confirmed by measuring the excited state lifetimes, which reveal the shifted band edge only increased carrier thermalization rates to the band edge and not interband charge recombination under both ultraviolet and visible excitation. Terahertz (time-domain) spectroscopy also reveals that the conduction mechanism remains unchanged after doping, suggesting the states are delocalized. PMID:26531849

  3. Planetary Exploration in ESA

    NASA Technical Reports Server (NTRS)

    Schwehm, Gerhard H.

    2005-01-01

    A viewgraph presentation on planetary exploration in the European Space Agency is shown. The topics include: 1) History of the Solar System Material; 2) ROSETTA: The Comet Mission; 3) A New Name For The Lander: PHILAE; 4) The Rosetta Mission; 5) Lander: Design Characteristics; 6) SMART-1 Mission; 7) MARS Express VENUS Express; 8) Planetary Exploration in ESA The Future.

  4. Self-absorption theory applied to rocket measurements of the nitric oxide (1, 0) gamma band in the daytime thermosphere

    NASA Technical Reports Server (NTRS)

    Eparvier, F. G.; Barth, C. A.

    1992-01-01

    Observations of the UV fluorescent emissions of the NO (1, 0) and (0, 1) gamma bands in the lower-thermospheric dayglow, made with a sounding rocket launched on March 7, 1989 from Poker Flat, Alaska, were analyzed. The resonant (1, 0) gamma band was found to be attenuated below an altitude of about 120 km. A self-absorption model based on Holstein transmission functions was developed for the resonant (1, 0) gamma band under varying conditions of slant column density and temperature and was applied for the conditions of the rocket flight. The results of the model agreed with the measured attenuation of the band, indicating the necessity of including self-absorption theory in the analysis of satellite and rocket limb data of NO.

  5. Retrieval of phytoplankton and colored detrital matter absorption coefficients with remote sensing reflectance in an ultraviolet band.

    PubMed

    Wei, Jianwei; Lee, Zhongping

    2015-02-01

    The light absorption of phytoplankton and colored detrital matter (CDM), which includes contribution of gelbstoff and detrital matters, has distinctive yet overlapping features in the ultraviolet (UV) and visible domain. The CDM absorption (a(dg)) increases exponentially with decreasing wavelength while the absorption coefficient of phytoplankton (a(ph)) generally decreases toward the shorter bands for the range of 350-450 nm. It has long been envisioned that including ocean color measurements in the UV range may help the separation of these two components from the remotely sensed ocean color spectrum. An attempt is made in this study to provide an analytical assessment of this expectation. We started with the development of an absorption decomposition model [quasi-analytical algorithm (QAA)-UV], analogous to the QAA, that partitions the total absorption coefficient using information at bands 380 and 440 nm. Compared to the retrieval results relying on the absorption information at 410 and 440 nm of the original QAA, our analyses indicate that QAA-UV can improve the retrieval of a(ph) and a(dg), although the improvement in accuracy is not significant for values at 440 nm. The performance of the UV-based algorithm is further evaluated with in situ measurements. The limited improvement observed with the field measurements highlights that the separation of a(dg) and a(ph) is highly dependent on the accuracy of the ocean color measurements and the estimated total absorption coefficient. PMID:25967770

  6. ESA proposes Moon initiative

    NASA Astrophysics Data System (ADS)

    1994-05-01

    Upon the invitation of the Swiss Government, the European Space Agency (ESA) is organising from Tuesday 31 May to Friday 3 June 1994 an international workshop on present and future plans for study and exploration of the Moon. This meeting will be held in Beatenberg, Switzerland, and attended by European, Russian and Japanese national space agencies as well as by NASA, the National Aeraunotics & Space Administration. For the media : * - a presentation will be held by Prof. Roger M. Bonnet, ESA Director of Science, and Mr. Jean-Jacques Dordain, Associate Director for Strategy, Planning and International Policy, at ESA Headquarters (8-10, rue Mario Nikis - 75015-PARIS) at 09h00 during a press breakfast on Monday 30 May. An info note describing the main lunar studies which will be presented at the Beatenberg workshop will be distributed on this occasion. * - On Friday 3 June, the press is invited to attend the closing session of the Beatenberg workshop starting at 09h30. This session will be followed by a briefing with the chairmen of the working groups and a lunch.

  7. Accurate measurements of ozone absorption cross-sections in the Hartley band

    NASA Astrophysics Data System (ADS)

    Viallon, J.; Lee, S.; Moussay, P.; Tworek, K.; Petersen, M.; Wielgosz, R. I.

    2015-03-01

    Ozone plays a crucial role in tropospheric chemistry, is the third largest contributor to greenhouse radiative forcing after carbon dioxide and methane and also a toxic air pollutant affecting human health and agriculture. Long-term measurements of tropospheric ozone have been performed globally for more than 30 years with UV photometers, all relying on the absorption of ozone at the 253.65 nm line of mercury. We have re-determined this cross-section and report a value of 11.27 x 10-18 cm2 molecule-1 with an expanded relative uncertainty of 0.86% (coverage factor k= 2). This is lower than the conventional value currently in use and measured by Hearn (1961) with a relative difference of 1.8%, with the consequence that historically reported ozone concentrations should be increased by 1.8%. In order to perform the new measurements of cross-sections with reduced uncertainties, a system was set up to generate pure ozone in the gas phase together with an optical system based on a UV laser with lines in the Hartley band, including accurate path length measurement of the absorption cell and a careful evaluation of possible impurities in the ozone sample by mass spectrometry and Fourier transform infrared spectroscopy. This resulted in new measurements of absolute values of ozone absorption cross-sections of 9.48 x 10-18, 10.44 x 10-18 and 11.07 x 10-18 cm2 molecule-1, with relative expanded uncertainties better than 0.7%, for the wavelengths (in vacuum) of 244.06, 248.32, and 257.34 nm respectively. The cross-section at the 253.65 nm line of mercury was determined by comparisons using a Standard Reference Photometer equipped with a mercury lamp as the light source. The newly reported value should be used in the future to obtain the most accurate measurements of ozone concentration, which are in closer agreement with non-UV-photometry based methods such as the gas phase titration of ozone with nitrogen monoxide.

  8. Two-photon absorption cross section measurement in the gamma band system of nitric oxide

    SciTech Connect

    Burris, J.F. Jr.

    1982-01-01

    A dye laser with a single longitudinal mode and very stable spatial mode structure has been constructed. With this laser system a four-wave mixing experiment was done in the gamma bands of nitric oxide using two photon resonance. Another four-wave mixing experiment was done in nitrogen using coherent anti-Stokes Raman scattering (CARS) and the two signals ratioed. Using accurately known values of the Raman scattering cross section, the third order susceptibility in NO was determined without needing to know the spatial and temporal properties of the dye lasers. From this susceptibility, the two photon absorption cross section was calculated with the explicit dependence of sigma/sup (2)/ upon X/sup (3)/ shown. For the R/sub 22/ + S/sub 12/(J'' = 9 1/2) (A/sup 2/..sigma..+(v' = 0) -- X/sup 2/..pi..(v'' = 0)) line, sigma/sup (2)/ = (1.0 +/- 0.6) x 10/sup -38/cm/sup 4/g(2/sub 1/-Vertical Barsub f/ is the normalized lineshape. Branching ratios for the A/sup 2/..sigma..+(v' = n) ..-->.. X/sup 2/..omega..(v'' = n)(n = o,...9) transitions of NO were also measured, Franck-Condon factors calculated and the lifetime of the A state determined.

  9. Absolute radical densities in etching plasmas determined by broad-band UV absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Booth, Jean-Paul; Cunge, Gilles; Neuilly, François; Sadeghi, Nader

    1998-08-01

    Broad-band UV absorption spectroscopy was used to determine radical densities in reactive gas plasmas generated in a 13.56 MHz capacitively coupled parallel plate reactor. Five radical species were detected: 0963-0252/7/3/021/img1, CF, AlF, 0963-0252/7/3/021/img2 and 0963-0252/7/3/021/img3. Absolute (line-integrated) 0963-0252/7/3/021/img1 densities were determined in 0963-0252/7/3/021/img5 and 0963-0252/7/3/021/img6 plasmas, as were the 0963-0252/7/3/021/img1 vibrational and rotational temperatures in the latter case. In 0963-0252/7/3/021/img5 plasmas the CF radical was also detected, along with the etch products AlF (from the Al powered electrode) and 0963-0252/7/3/021/img2 (when an Si substrate was present). The fraction that 0963-0252/7/3/021/img2 comprises of the total etch products was estimated. Finally, the 0963-0252/7/3/021/img3 dimer was detected in an 0963-0252/7/3/021/img12 plasma in the presence of an Si substrate. This simple technique allows absolute concentrations of many key reactive species to be determined in reactive plasmas, without the need to analyse the complex rotational spectra of these polyatomic molecules.

  10. Band gap tuning and optical absorption in type-II InAs/GaSb mid infrared short period superlattices: 14 bands K Dot-Operator p study

    SciTech Connect

    AbuEl-Rub, Khaled M.

    2012-09-06

    The MBE growth of short-period InAs/GaSb type-II superlattice structures, varied around 20.5 A InAs/24 A GaSb were [J. Applied physics, 96, 2580 (2004)] carried out by Haugan et al. These SLs were designed to produce devices with an optimum mid-infrared photoresponse and a sharpest photoresponse cutoff. We have used a realistic and reliable 14-band k.p formalism description of the superlattice electronic band structure to calculate the absorption coefficient in such short-period InAs/GaSb type-II superlattices. The parameters for this formalism are known from fitting to independent experiments for the bulk materials. The band-gap energies are obtained without any fitting parameters, and are in good agreement with experimental data.

  11. Structural diversity of the 3-micron absorption band in Enceladus’ plume from Cassini VIMS: Insights into subsurface environmental conditions

    NASA Astrophysics Data System (ADS)

    Dhingra, Deepak; Hedman, Matthew M.; Clark, Roger N.

    2015-11-01

    Water ice particles in Enceladus’ plume display their diagnostic 3-micron absorption band in Cassini VIMS data. These near infrared measurements of the plume also exhibit noticeable variations in the character of this band. Mie theory calculations reveal that the shape and location of the 3-micron band are controlled by a number of environmental and structural parameters. Hence, this band provides important insights into the properties of the water ice grains and about the subsurface environmental conditions under which they formed. For example, the position of the 3-micron absorption band minimum can be used to distinguish between crystalline and amorphous forms of water ice and to constrain the formation temperature of the ice grains. VIMS data indicates that the water ice grains in the plume are dominantly crystalline which could indicate formation temperatures above 113 K [e.g. 1, 2]. However, there are slight (but observable) variations in the band minimum position and band shape that may hint at the possibility of varying abundance of amorphous ice particles within the plume. The modeling results further indicate that there are systematic shifts in band minimum position with temperature for any given form of ice but the crystalline and amorphous forms of water ice are still distinguishable at VIMS spectral resolution. Analysis of the eruptions from individual source fissures (tiger stripes) using selected VIMS observations reveal differences in the 3-micron band shape that may reflect differences in the size distributions of the water ice particles along individual fissures. Mie theory models suggest that big ice particles (>3 micron) may be an important component of the plume.[1] Kouchi, A., T. Yamamoto, T. Kozasa, T. Kuroda, and J. M. Greenberg (1994) A&A, 290, 1009-1018 [2] Mastrapa, R. M. E., W. M. Grundy, and M. S. Gudipati (2013) in M. S. Gudipati and J. Castillo-Rogez (Eds.), The Science of Solar System Ices, pp. 371.

  12. Airborne imaging spectrometer data of the Ruby Mountains, Montana: Mineral discrimination using relative absorption band-depth images

    USGS Publications Warehouse

    Crowley, J.K.; Brickey, D.W.; Rowan, L.C.

    1989-01-01

    Airborne imaging spectrometer data collected in the near-infrared (1.2-2.4 ??m) wavelength range were used to study the spectral expression of metamorphic minerals and rocks in the Ruby Mountains of southwestern Montana. The data were analyzed by using a new data enhancement procedure-the construction of relative absorption band-depth (RBD) images. RBD images, like bandratio images, are designed to detect diagnostic mineral absorption features, while minimizing reflectance variations related to topographic slope and albedo differences. To produce an RBD image, several data channels near an absorption band shoulder are summed and then divided by the sum of several channels located near the band minimum. RBD images are both highly specific and sensitive to the presence of particular mineral absorption features. Further, the technique does not distort or subdue spectral features as sometimes occurs when using other data normalization methods. By using RBD images, a number of rock and soil units were distinguished in the Ruby Mountains including weathered quartz - feldspar pegmatites, marbles of several compositions, and soils developed over poorly exposed mica schists. The RBD technique is especially well suited for detecting weak near-infrared spectral features produced by soils, which may permit improved mapping of subtle lithologic and structural details in semiarid terrains. The observation of soils rich in talc, an important industrial commodity in the study area, also indicates that RBD images may be useful for mineral exploration. ?? 1989.

  13. Depth and Shape of the 0.94-microm Water Vapor Absorption Band for Clear and Cloudy Skies.

    PubMed

    Volz, F E

    1969-11-01

    Sky radiation near zenith and solar radiation in the rhosigmatau band region were recorded by means of a rotating interference filter (lambda0.98-0.88 microm) and a silicon detector. Although the spectral resolution of the simple spectrometer was not high, the water vapor content of the cloud free atmosphere was obtained with reasonable accuracy. The band depth of the radiation from thin, bright clouds was only slightly greater than that of the cloud free atmosphere, but dense and dark clouds showed deep bands mainly caused by increased path length as a result of multiple scattering. Considerable distortion of the band due to absorption by liquid water is observed in the radiation from very dark and dense clouds, and sometimes during snowfall. Some laboratory measurements are also discussed. PMID:20076009

  14. ESA SnowLab project

    NASA Astrophysics Data System (ADS)

    Wiesmann, Andreas; Caduff, Rafael; Frey, Othmar; Werner, Charles

    2016-04-01

    Retrieval of the snow water equivalaent (SWE) from passive microwave observations dates back over three decades to initial studies made using the first operational radiometers in space. However, coarse spatial resolution (25 km) is an acknowledged limitation for the application of passive microwave measurements. The natural variability of snow cover itself is also notable; properties such as stratigraphy and snow microstructure change both spatially and over time, affecting the microwave signature. To overcome this deficit, the satellite mission COld REgions Hydrology High-resolution Observatory (CoReH2O) was proposed to the European Space Agency (ESA) in 2005 in response to the call for Earth Explorer 7 candidate missions. CoReH2O was a dual frequency (X- and Ku-band) SAR mission aimed to provide maps of SWE over land and snow accumulation on glaciers at a spatial resolution of 200 to 500 meters with an unprecedented accuracy. Within the frame of preparatory studies for CoReH2O Phase A, ESA undertook several research initiatives from 2009 to 2013 to study the mission concept and capabilities of the proposed sensor. These studies provided a wealth of information on emission and backscattering signatures of natural snow cover, which can be exploited to study new potential mission concepts for retrieval of snow cover properties and other elements of the cryosphere. Currently data related to multi-frequency, multi-polarisation, multitemporal of active and passive microwave measurements are still not available. In addition, new methods related to e.g. tomography are currently under development and need to be tested with real data. Also, the potential of interferometric and polarimetric measurements of the snow cover and its possible impact for novel mission/retrieval concepts must be assessed. . The objective of the SnowLab activity is to fill this gap and complement these datasets from earlier campaigns by acquiring a comprehensive multi-frequency, multi

  15. Evidence for strange stars from joint observation of harmonic absorption bands and of redshift

    NASA Astrophysics Data System (ADS)

    Bagchi, Manjari; Ray, Subharthi; Dey, Mira; Dey, Jishnu

    2006-05-01

    From recent reports on terrestrial heavy ion collision experiments it appears that one may not obtain information about the existence of asymptotic freedom (AF) and chiral symmetry restoration (CSR) for quarks of QCD at high density. This information may still be obtained from compact stars - if they are made up of strange quark matter (SQM). Very high gravitational redshift lines (GRL), seen from some compact stars, seem to suggest high ratios of mass and radius (M/R) for them. This is suggestive of strange stars (SS) and can in fact be fitted very well with SQM equation of state (EOS) deduced with built in AF and CSR. In some other stars broad absorption bands (BAB) appear at about ~0.3keV and multiples thereof, that may fit in very well with resonance with harmonic compressional breathing mode frequencies of these SS. Emission at these frequencies are also observed in six stars. If these two features of large GRL and BAB were observed together in a single star, it would strengthen the possibility for the existence of SS in nature and would vindicate the current dogma of AF and CSR that we believe in QCD. Recently, in 4U 1700 - 24, both features appear to be detected, which may well be interpreted as observation of SS - although the group that analyzed the data did not observe this possibility. We predict that if the shifted lines, that has been observed, are from neon with GRL shift z= 0.4- then the compact object emitting it is a SS of mass 1.2Msolar and radius 7km. In addition the fit to the spectrum leaves a residual with broad dips at 0.35keV and multiples thereof, as in 1E 1207 - 5209 which is again suggestive of SS.

  16. Mapping atomic and diffuse interstellar band absorption across the Magellanic Clouds and the Milky Way

    NASA Astrophysics Data System (ADS)

    Bailey, Mandy; van Loon, Jacco Th.; Sarre, Peter J.; Beckman, John E.

    2015-12-01

    Diffuse interstellar bands (DIBs) trace warm neutral and weakly ionized diffuse interstellar medium (ISM). Here we present a dedicated, high signal-to-noise spectroscopic survey of two of the strongest DIBs, at 5780 and 5797 Å, in optical spectra of 666 early-type stars in the Small and Large Magellanic Clouds, along with measurements of the atomic Na I D and Ca II K lines. The resulting maps show for the first time the distribution of DIB carriers across large swathes of galaxies, as well as the foreground Milky Way ISM. We confirm the association of the 5797 Å DIB with neutral gas, and the 5780 Å DIB with more translucent gas, generally tracing the star-forming regions within the Magellanic Clouds. Likewise, the Na I D line traces the denser ISM whereas the Ca II K line traces the more diffuse, warmer gas. The Ca II K line has an additional component at ˜200-220 km s-1 seen towards both Magellanic Clouds; this may be associated with a pan-Magellanic halo. Both the atomic lines and DIBs show sub-pc-scale structure in the Galactic foreground absorption; the 5780 and 5797 Å DIBs show very little correlation on these small scales, as do the Ca II K and Na I D lines. This suggests that good correlations between the 5780 and 5797 Å DIBs, or between Ca II K and Na I D, arise from the superposition of multiple interstellar structures. Similarity in behaviour between DIBs and Na I in the Small Magellanic Cloud (SMC), Large Magellanic Cloud (LMC) and Milky Way suggests the abundance of DIB carriers scales in proportion to metallicity.

  17. The absorption coefficient of the liquid N2 2.15-micron band and application to Triton

    NASA Technical Reports Server (NTRS)

    Grundy, William M.; Fink, Uwe

    1991-01-01

    The present measurements of the temperature dependence exhibited by the liquid N2 2.15-micron 2-0 collision-induced band's absorption coefficient and integrated absorption show the latter to be smaller than that of the N2 gas, and to decrease with decreasing temperature. Extrapolating this behavior to Triton's nominal surface temperature yields a new estimate of the N2-ice grain size on the Triton south polar cap; a mean N2 grain size of 0.7-3.0 cm is consistent with grain growth rate calculation results.

  18. First-principles study of the band structure and optical absorption of CuGaS2

    NASA Astrophysics Data System (ADS)

    Aguilera, Irene; Vidal, Julien; Wahnón, Perla; Reining, Lucia; Botti, Silvana

    2011-08-01

    CuGaS2 is the most promising chalcopyrite host for intermediate-band thin-film solar cells. Standard Kohn-Sham density functional theory fails in describing the band structure of chalcopyrite materials, due to the strong underestimation of the band gap and the poor description of p-d hybridization, which makes it inadvisable to use this approach to study the states in the gap induced by doping. We used a state-of-the-art restricted self-consistent GW approach to determine the electronic states of CuGaS2: in the energy range of interest for optical absorption, the GW corrections shift the Kohn-Sham bands almost rigidly, as we proved through analysis of the effective masses, bandwidths, and relative position of the conduction energy valleys. Furthermore, starting from the GW quasiparticle bands, we calculated optical absorption spectra using different approximations. We show that the time-dependent density functional theory can be an efficient alternative to the solution of the Bethe-Salpeter equation when the exchange-correlation kernels derived from the Bethe-Salpeter equation are employed. This conclusion is important for further studies of optical properties of supercells including dopants.

  19. X-ray absorption and reflection as probes of the GaN conduction bands: Theory and experiments

    SciTech Connect

    Lambrecht, W.R.L.; Rashkeev, S.N.; Segall, B.

    1997-04-01

    X-ray absorption measurements are a well-known probe of the unoccupied states in a material. The same information can be obtained by using glancing angle X-ray reflectivity. In spite of several existing band structure calculations of the group III nitrides and previous optical studies in UV range, a direct probe of their conduction band densities of states is of interest. The authors performed a joint experimental and theoretical investigation using both of these experimental techniques for wurtzite GaN.

  20. First detection of ionized helium absorption lines in infrared K band spectra of O-type stars

    NASA Technical Reports Server (NTRS)

    Conti, Peter S.; Block, David L.; Geballe, T. R.; Hanson, Margaret M.

    1993-01-01

    We have obtained high SNR, moderate-resolution K band spectra of two early O-type main sequence stars, HD 46150 O5 V, and HD 46223 O4 V, in the Rosette Nebula. We report the detection, for the first time, of the 2.189 micron He II line in O-type stars. Also detected is the 2.1661 micron Br-gamma line in absorption. The 2.058 micron He I line appears to be present in absorption in both stars, although its appearance at our resolution is complicated by atmospheric features. These three lines can form the basis for a spectral classification system for hot stars in the K band that may be used at infrared wavelengths to elucidate the nature of those luminous stars in otherwise obscured H II and giant H II regions.

  1. Detection of metal stress in boreal forest species using the 0.67-micron chlorophyll absorption band

    NASA Technical Reports Server (NTRS)

    Singhroy, Vernon H.; Kruse, Fred A.

    1991-01-01

    Several recent studies have shown that a shift of the red-edge inflection near 0.70 micron in vegetation reflectance spectra is an indicator of metal stress, partially attributable to changes in chlorophyll concentration. This 'red-edge shift', however, is difficult to detect and has been reported both toward longer (red) and shorter (blue) wavelengths. Our work demonstrates that direct measurement of the depth and width of the chlorophyll absorption band at 0.67 micron using digital feature extraction and absorption band characterization procedures developed for the analysis of mineral spectra is a more consistent indicator of metal stress. Additionally, the magnitude of these parameters is generally greater than that of the red edge shift and thus should be more amenable to detection and mapping using field and aircraft spectrometers.

  2. 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.

  3. The Pt2 (1,0) band of System VI in the near infrared by intracavity laser absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    O'Brien, Leah C.; O'Brien, James J.

    2011-05-01

    Intracavity laser absorption spectroscopy has been used to record rotationally resolved electronic spectra of Pt2 in the near infrared. The metal dimers were created using a 50 mm-long, platinum-lined hollow cathode plasma discharge. The observed transition at 12 937 cm-1 is identified as the (1,0) band of System VI, with state symmetries Ω = 0 - X Ω = 0.

  4. Precise ro-vibrational analysis of molecular bands forbidden in absorption: The ν8 +ν10 band of 13C2H4

    NASA Astrophysics Data System (ADS)

    Ulenikov, O. N.; Gromova, O. V.; Bekhtereva, E. S.; Kashirina, N. V.; Maul, C.; Bauerecker, S.

    2015-10-01

    The high resolution spectra of the 13C2H4 molecule was recorded with a Bruker IFS 120 Fourier transform spectrometer and theoretically analyzed in the 1650 - 1800cm-1 region of the ν8 +ν10 band which is forbidden in absorption. About 1200 experimental transitions with the maximum values of quantum numbers Jmax. = 34 and Kamax. = 17 were assigned to the ν8 +ν10 band. On that basis the 516 high accuracy ro-vibrational energies of the (v8=v10=1) vibrational state, as well as energy levels with J ≤ 2 of the (v4 =v8 = 1) and (v7 =v8 = 1) vibrational states, were determined which then were used as input data in the weighted fit of spectroscopic parameters of the Hamiltonian (strong local resonance interactions of the ν8 +ν10 band with the bands ν4 +ν8 and ν7 +ν8 have been taken into account). A set of 34 vibrational, rotational, centrifugal distortion, and resonance interaction parameters was obtained from the fit. These parameters reproduce positions of about 1200 experimentally recorded and assigned transitions with the rms error drms = 0.00018cm-1 (blended and very weak transitions are not taken into account in that case).

  5. Wide angle and narrow-band asymmetric absorption in visible and near-infrared regime through lossy Bragg stacks.

    PubMed

    Shu, Shiwei; Zhan, Yawen; Lee, Chris; Lu, Jian; Li, Yang Yang

    2016-01-01

    Absorber is an important component in various optical devices. Here we report a novel type of asymmetric absorber in the visible and near-infrared spectrum which is based on lossy Bragg stacks. The lossy Bragg stacks can achieve near-perfect absorption at one side and high reflection at the other within the narrow bands (several nm) of resonance wavelengths, whereas display almost identical absorption/reflection responses for the rest of the spectrum. Meanwhile, this interesting wavelength-selective asymmetric absorption behavior persists for wide angles, does not depend on polarization, and can be ascribed to the lossy characteristics of the Bragg stacks. Moreover, interesting Fano resonance with easily tailorable peak profiles can be realized using the lossy Bragg stacks. PMID:27251768

  6. Wide angle and narrow-band asymmetric absorption in visible and near-infrared regime through lossy Bragg stacks

    NASA Astrophysics Data System (ADS)

    Shu, Shiwei; Zhan, Yawen; Lee, Chris; Lu, Jian; Li, Yang Yang

    2016-06-01

    Absorber is an important component in various optical devices. Here we report a novel type of asymmetric absorber in the visible and near-infrared spectrum which is based on lossy Bragg stacks. The lossy Bragg stacks can achieve near-perfect absorption at one side and high reflection at the other within the narrow bands (several nm) of resonance wavelengths, whereas display almost identical absorption/reflection responses for the rest of the spectrum. Meanwhile, this interesting wavelength-selective asymmetric absorption behavior persists for wide angles, does not depend on polarization, and can be ascribed to the lossy characteristics of the Bragg stacks. Moreover, interesting Fano resonance with easily tailorable peak profiles can be realized using the lossy Bragg stacks.

  7. Wide angle and narrow-band asymmetric absorption in visible and near-infrared regime through lossy Bragg stacks

    PubMed Central

    Shu, Shiwei; Zhan, Yawen; Lee, Chris; Lu, Jian; Li, Yang Yang

    2016-01-01

    Absorber is an important component in various optical devices. Here we report a novel type of asymmetric absorber in the visible and near-infrared spectrum which is based on lossy Bragg stacks. The lossy Bragg stacks can achieve near-perfect absorption at one side and high reflection at the other within the narrow bands (several nm) of resonance wavelengths, whereas display almost identical absorption/reflection responses for the rest of the spectrum. Meanwhile, this interesting wavelength-selective asymmetric absorption behavior persists for wide angles, does not depend on polarization, and can be ascribed to the lossy characteristics of the Bragg stacks. Moreover, interesting Fano resonance with easily tailorable peak profiles can be realized using the lossy Bragg stacks. PMID:27251768

  8. Absolute Rovibrational Intensities of C-12O2-16 Absorption Bands in the 3090-3850/ CM Spectral Region

    NASA Technical Reports Server (NTRS)

    Devi, V. Malathy; Benner, D. Chris; Rinsland, Curtis P.; Smith, Mary Ann H.

    1998-01-01

    A multispectrum nonlinear least-squares fitting technique has been used to determine the absolute intensities for approximately 1500 spectral lines in 36 vibration - rotation bands Of C-12O2-16 between 3090 and 3850/ cm. A total of six absorption spectra of a high- purity (99.995% minimum) natural sample of carbon dioxide were used in the analysis. The spectral data (0.01/cm resolution) were recorded at room temperature and low pressure (1 to 10 Torr) using the McMath-Pierce Fourier transform spectrometer of the National Solar Observatory (NSO) on Kitt Peak. The absorption path lengths for these spectra varied between 24.86 and 385.76 m. The first experimental determination of the intensity of the theoretically predicted 2(nu)(sub 2, sup 2) + nu(sub 3) "forbidden" band has been made. The measured line intensities obtained for each band have been analyzed to determine the vibrational band intensity, S(sub nu), in /cm/( molecule/sq cm) at 296 K, square of the rotationless transition dipole moment |R|(exp 2) in Debye, as well as the nonrigid rotor coefficients. The results are compared to the values listed in the 1996 HITRAN database which are obtained using the direct numerical diagonalization (DND) technique as well as to other published values where available.

  9. Analysis of airborne imaging spectrometer data for the Ruby Mountains, Montana, by use of absorption-band-depth images

    NASA Technical Reports Server (NTRS)

    Brickey, David W.; Crowley, James K.; Rowan, Lawrence C.

    1987-01-01

    Airborne Imaging Spectrometer-1 (AIS-1) data were obtained for an area of amphibolite grade metamorphic rocks that have moderate rangeland vegetation cover. Although rock exposures are sparse and patchy at this site, soils are visible through the vegetation and typically comprise 20 to 30 percent of the surface area. Channel averaged low band depth images for diagnostic soil rock absorption bands. Sets of three such images were combined to produce color composite band depth images. This relative simple approach did not require extensive calibration efforts and was effective for discerning a number of spectrally distinctive rocks and soils, including soils having high talc concentrations. The results show that the high spectral and spatial resolution of AIS-1 and future sensors hold considerable promise for mapping mineral variations in soil, even in moderately vegetated areas.

  10. Voigt deconvolution method and its applications to pure oxygen absorption spectrum at 1270 nm band

    NASA Astrophysics Data System (ADS)

    AL-Jalali, Muhammad A.; Aljghami, Issam F.; Mahzia, Yahia M.

    2016-03-01

    Experimental spectral lines of pure oxygen at 1270 nm band were analyzed by Voigt deconvolution method. The method gave a total Voigt profile, which arises from two overlapping bands. Deconvolution of total Voigt profile leads to two Voigt profiles, the first as a result of O2 dimol at 1264 nm band envelope, and the second from O2 monomer at 1268 nm band envelope. In addition, Voigt profile itself is the convolution of Lorentzian and Gaussian distributions. Competition between thermal and collisional effects was clearly observed through competition between Gaussian and Lorentzian width for each band envelope. Voigt full width at half-maximum height (Voigt FWHM) for each line, and the width ratio between Lorentzian and Gaussian width (ΓLΓG- 1) have been investigated. The following applied pressures were at 1, 2, 3, 4, 5, and 8 bar, while the temperatures were at 298 K, 323 K, 348 K, and 373 K range.

  11. Voigt deconvolution method and its applications to pure oxygen absorption spectrum at 1270 nm band.

    PubMed

    Al-Jalali, Muhammad A; Aljghami, Issam F; Mahzia, Yahia M

    2016-03-15

    Experimental spectral lines of pure oxygen at 1270 nm band were analyzed by Voigt deconvolution method. The method gave a total Voigt profile, which arises from two overlapping bands. Deconvolution of total Voigt profile leads to two Voigt profiles, the first as a result of O2 dimol at 1264 nm band envelope, and the second from O2 monomer at 1268 nm band envelope. In addition, Voigt profile itself is the convolution of Lorentzian and Gaussian distributions. Competition between thermal and collisional effects was clearly observed through competition between Gaussian and Lorentzian width for each band envelope. Voigt full width at half-maximum height (Voigt FWHM) for each line, and the width ratio between Lorentzian and Gaussian width (ΓLΓG(-1)) have been investigated. The following applied pressures were at 1, 2, 3, 4, 5, and 8 bar, while the temperatures were at 298 K, 323 K, 348 K, and 373 K range. PMID:26709019

  12. Time-Resolved IR-Absorption Spectroscopy of Hot-Electron Dynamics in Satellite and Upper Conduction Bands in GaP

    NASA Technical Reports Server (NTRS)

    Cavicchia, M. A.; Alfano, R. R.

    1995-01-01

    The relaxation dynamics of hot electrons in the X6 and X7 satellite and upper conduction bands in GaP was directly measured by femtosecond UV-pump-IR-probe absorption spectroscopy. From a fit to the induced IR-absorption spectra the dominant scattering mechanism giving rise to the absorption at early delay times was determined to be intervalley scattering of electrons out of the X7 upper conduction-band valley. For long delay times the dominant scattering mechanism is electron-hole scattering. Electron transport dynamics of the upper conduction band of GaP has been time resolved.

  13. Ground-based Photon Path Measurements from Solar Absorption Spectra of the O2 A-band

    NASA Technical Reports Server (NTRS)

    Yang, Z.; Wennberg, P. O.; Cageao, R. P.; Pongetti, T. J.; Toon, G. C.; Sander, S. P.

    2005-01-01

    High-resolution solar absorption spectra obtained from Table Mountain Facility (TMF, 34.38degN, 117.68degW, 2286 m elevation) have been analyzed in the region of the O2 A-band. The photon paths of direct sunlight in clear sky cases are retrieved from the O2 absorption lines and compared with ray-tracing calculations based on the solar zenith angle and surface pressure. At a given zenith angle, the ratios of retrieved to geometrically derived photon paths are highly precise (approx.0.2%), but they vary as the zenith angle changes. This is because current models of the spectral lineshape in this band do not properly account for the significant absorption that exists far from the centers of saturated lines. For example, use of a Voigt function with Lorentzian far wings results in an error in the retrieved photon path of as much as 5%, highly correlated with solar zenith angle. Adopting a super-Lorentz function reduces, but does not completely eliminate this problem. New lab measurements of the lineshape are required to make further progress.

  14. Semi-Empirical Validation of the Cross-Band Relative Absorption Technique for the Measurement of Molecular Mixing Ratios

    NASA Technical Reports Server (NTRS)

    Pliutau, Denis; Prasad, Narasimha S

    2013-01-01

    Studies were performed to carry out semi-empirical validation of a new measurement approach we propose for molecular mixing ratios determination. The approach is based on relative measurements in bands of O2 and other molecules and as such may be best described as cross band relative absorption (CoBRA). . The current validation studies rely upon well verified and established theoretical and experimental databases, satellite data assimilations and modeling codes such as HITRAN, line-by-line radiative transfer model (LBLRTM), and the modern-era retrospective analysis for research and applications (MERRA). The approach holds promise for atmospheric mixing ratio measurements of CO2 and a variety of other molecules currently under investigation for several future satellite lidar missions. One of the advantages of the method is a significant reduction of the temperature sensitivity uncertainties which is illustrated with application to the ASCENDS mission for the measurement of CO2 mixing ratios (XCO2). Additional advantages of the method include the possibility to closely match cross-band weighting function combinations which is harder to achieve using conventional differential absorption techniques and the potential for additional corrections for water vapor and other interferences without using the data from numerical weather prediction (NWP) models.

  15. Semi-empirical validation of the cross-band relative absorption technique for the measurement of molecular mixing ratios

    NASA Astrophysics Data System (ADS)

    Pliutau, Denis; Prasad, Narasimha S.

    2013-05-01

    Studies were performed to carry out semi-empirical validation of a new measurement approach we propose for molecular mixing ratios determination. The approach is based on relative measurements in bands of O2 and other molecules and as such may be best described as cross band relative absorption (CoBRA). The current validation studies rely upon well verified and established theoretical and experimental databases, satellite data assimilations and modeling codes such as HITRAN, line-by-line radiative transfer model (LBLRTM), and the modern-era retrospective analysis for research and applications (MERRA). The approach holds promise for atmospheric mixing ratio measurements of CO2 and a variety of other molecules currently under investigation for several future satellite lidar missions. One of the advantages of the method is a significant reduction of the temperature sensitivity uncertainties which is illustrated with application to the ASCENDS mission for the measurement of CO2 mixing ratios (XCO2). Additional advantages of the method include the possibility to closely match cross-band weighting function combinations which is harder to achieve using conventional differential absorption techniques and the potential for additional corrections for water vapor and other interferences without using the data from numerical weather prediction (NWP) models.

  16. Signatures of a conical intersection in photofragment distributions and absorption spectra: Photodissociation in the Hartley band of ozone

    SciTech Connect

    Picconi, David; Grebenshchikov, Sergy Yu.

    2014-08-21

    Photodissociation of ozone in the near UV is studied quantum mechanically in two excited electronic states coupled at a conical intersection located outside the Franck-Condon zone. The calculations, performed using recent ab initio PESs, provide an accurate description of the photodissociation dynamics across the Hartley/Huggins absorption bands. The observed photofragment distributions are reproduced in the two electronic dissociation channels. The room temperature absorption spectrum, constructed as a Boltzmann average of many absorption spectra of rotationally excited parent ozone, agrees with experiment in terms of widths and intensities of diffuse structures. The exit channel conical intersection contributes to the coherent broadening of the absorption spectrum and directly affects the product vibrational and translational distributions. The photon energy dependences of these distributions are strikingly different for fragments created along the adiabatic and the diabatic paths through the intersection. They can be used to reverse engineer the most probable geometry of the non-adiabatic transition. The angular distributions, quantified in terms of the anisotropy parameter β, are substantially different in the two channels due to a strong anticorrelation between β and the rotational angular momentum of the fragment O{sub 2}.

  17. Higher-order mode absorption measurement of X-band choke-mode cavities in a radial line structure

    NASA Astrophysics Data System (ADS)

    Zha, Hao; Shi, Jiaru; Wu, Xiaowei; Chen, Huaibi

    2016-04-01

    An experiment is presented to study the higher-order mode (HOM) suppression of X-band choke-mode structures with a vector network analyzer (VNA). Specific radial line disks were built to test the reflection from the corresponding damping load and different choke geometries. The mismatch between the radial lines and the VNA was calibrated through a special multi-short-load calibration method. The measured reflections of different choke geometries showed good agreement with the theoretical calculations and verified the HOM absorption feature of each geometric design.

  18. Band-Selective Measurements of Electron Dynamics in VO2 UsingFemtosecond Near-Edge X-Ray Absorption

    SciTech Connect

    Cavalleri, A.; Rini, M.; Chong, H.H.W.; Fourmaux, S.; Glover,T.E.; Heimann, P.A.; Kieffer, J.C.; Schoenlein, R.W.

    2005-07-20

    We report on the first demonstration of femtosecond x-rayabsorption spectroscopy, made uniquely possible by the use of broadlytunable bending-magnet radiation from "laser-sliced" electron buncheswithin a synchrotron storage ri ng. We measure the femtosecond electronicrearrangements that occur during the photoinduced insulator-metal phasetransition in VO2. Symmetry- and element-specific x-ray absorption fromV2p and O1s core levels (near 500 eV) separately measures the fillingdynamics of differently hybridized V3d-O2p electronic bands near theFermi level.

  19. Analysis of functional groups in atmospheric aerosols by infrared spectroscopy: sparse methods for statistical selection of relevant absorption bands

    NASA Astrophysics Data System (ADS)

    Takahama, Satoshi; Ruggeri, Giulia; Dillner, Ann M.

    2016-07-01

    Various vibrational modes present in molecular mixtures of laboratory and atmospheric aerosols give rise to complex Fourier transform infrared (FT-IR) absorption spectra. Such spectra can be chemically informative, but they often require sophisticated algorithms for quantitative characterization of aerosol composition. Naïve statistical calibration models developed for quantification employ the full suite of wavenumbers available from a set of spectra, leading to loss of mechanistic interpretation between chemical composition and the resulting changes in absorption patterns that underpin their predictive capability. Using sparse representations of the same set of spectra, alternative calibration models can be built in which only a select group of absorption bands are used to make quantitative prediction of various aerosol properties. Such models are desirable as they allow us to relate predicted properties to their underlying molecular structure. In this work, we present an evaluation of four algorithms for achieving sparsity in FT-IR spectroscopy calibration models. Sparse calibration models exclude unnecessary wavenumbers from infrared spectra during the model building process, permitting identification and evaluation of the most relevant vibrational modes of molecules in complex aerosol mixtures required to make quantitative predictions of various measures of aerosol composition. We study two types of models: one which predicts alcohol COH, carboxylic COH, alkane CH, and carbonyl CO functional group (FG) abundances in ambient samples based on laboratory calibration standards and another which predicts thermal optical reflectance (TOR) organic carbon (OC) and elemental carbon (EC) mass in new ambient samples by direct calibration of infrared spectra to a set of ambient samples reserved for calibration. We describe the development and selection of each calibration model and evaluate the effect of sparsity on prediction performance. Finally, we ascribe

  20. Band Structure of the Rhodobacter sphaeroides Photosynthetic Reaction Center from Low-Temperature Absorption and Hole-Burned Spectra.

    PubMed

    Rancova, Olga; Jankowiak, Ryszard; Kell, Adam; Jassas, Mahboobe; Abramavicius, Darius

    2016-06-30

    Persistent/transient spectral hole burning (HB) and computer simulations are used to provide new insight into the excitonic structure and excitation energy transfer of the widely studied bacterial reaction center (bRC) of Rhodobacter (Rb.) sphaeroides. We focus on site energies of its cofactors and electrochromic shifts induced in the chemically oxidized (P(+)) and charge-separated (P(+)QM(-)) states. Theoretical models lead to two alternative interpretations of the H-band. On the basis of our experimental and simulation data, we suggest that the bleach near 813-825 nm in transient HB spectra in the P(+)QM(-) state, often assigned to the upper exciton component of the special pair, is mostly due to different electrochromic shifts of the BL/M cofactors. From the exciton compositions in the charge-neutral (CN) bRC, the weak fourth excitonic band near 780 nm can be denoted PY+, that is, the upper excitonic band of the special pair, which in the CN bRC behaves as a delocalized state over PM and PL pigments that weakly mixes with accessory BChls. Thus, the shoulder in the absorption of Rb. sphaeroides near 813-815 nm does not contain the PY+ exciton band. PMID:27266271

  1. Iron absorption band analysis for the discrimination of iron rich zones

    NASA Technical Reports Server (NTRS)

    Rowan, L. C. (Principal Investigator)

    1973-01-01

    The author has identified the following significant results. A lineament study of the Nevada test site is near completion. Two base maps (1:500,000) have been prepared, one of band 7 lineaments and the other of band 5 lineaments. In general, more lineaments and more faults are seen on band 5. About 45% of the lineaments appear to be faults and contacts, the others being predominantly streams, roads, railway tracks, and mountain crests. About 25% of the lineaments are unidentified so far. Special attention is being given to unmapped extensions of faults, groups of unmapped lineaments, and known mineralized areas and alteration zones. Earthquake epicenters recorded from 1869 to 1963 have been plotted on the two base maps. Preliminary examination as yet indicates no basic correlation with the lineaments. Attempts are being made to subtract bands optically, using an I2S viewer, an enlarger, and a data color viewer. Success has been limited so far due to technical difficulties, mainly vignetting and poor light sources, within the machines. Some vegetation and rock type differences, however, have been discerned.

  2. High resolution absorption spectroscopy of the ν1=2-6 acetylenic overtone bands of propyne: Spectroscopy and dynamics

    NASA Astrophysics Data System (ADS)

    Campargue, A.; Biennier, L.; Garnache, A.; Kachanov, A.; Romanini, D.; Herman, M.

    1999-11-01

    The rotationally resolved nν1 (n=2-6) overtone transitions of the CH acetylenic stretching of propyne (CH3-C≡C-H) have been recorded by using Fourier transform spectroscopy (n=2), various intracavity laser absorption spectrometers (n=3, 4, and 6) and cavity ring down spectroscopy (CRDS) (n=5). The 2ν1, 3ν1, and 6ν1 bands exhibit a well-resolved and mostly unperturbed J-rotational structure, whose analysis is reported. The 5ν1 band recorded by pulsed CRDS shows an unresolved rotational envelope. In the region of 12 700 cm-1, an anharmonic interaction is confirmed between 4ν1 and 3ν1+ν3+ν5. The band at a higher wave number in this dyad exhibits a partly resolved K-structure, whose analysis is reported. The mixing coefficient of the two interacting states is determined consistently using different procedures. The 1/35 anharmonic resonance evidenced in the 4ν1 manifold induces weaker intensity borrowing from the 2ν1 and 3ν1 levels to the ν1+ν3+ν5 and 2ν1+ν3+ν5 level, respectively, which have been predicted and identified. Several hot bands around the 2ν1, 3ν1, and 3ν1+ν3+ν5 bands arising from the ν9=1 and ν10=1 and 2 bending levels are identified and rotationally analyzed, also leading to determine x1,9 [-20.3(3) cm-1], x1,10 [-1.7975(75) cm-1], and x3,10 [-6.56 cm-1]. The J-clumps of the P and R branches in the 6ν1 band at 18 499 cm-1 show a Lorentzian homogeneous profile mostly J-independent with an average full width at half maximum (FWHM) of 0.17 cm-1, attributed to arising from the intramolecular vibrational energy redistribution towards the bath of vibrational states. A detailed comparative examination of the fine structure in all investigated nν1 (n=2 to 7) overtone bands and the similar behavior of the cold and hot bands arising from ν10=1 definitively suggests that a highly specific low-order anharmonic coupling, still unidentified, dominates the hierarchy of interaction mechanisms connecting the nν1 levels to the background

  3. Development of a narrow-band, tunable, frequency-quadrupled diode laser for UV absorption spectroscopy.

    PubMed

    Koplow, J P; Kliner, D A; Goldberg, L

    1998-06-20

    A compact, lightweight, low-power-consumption source of tunable, narrow-bandwidth blue and UV radiation is described. In this source, a single-longitudinal-mode diode laser seeds a pulsed, GaAlAs tapered amplifier whose ~860-nm output is frequency quadrupled by two stages of single-pass frequency doubling. Performance of the laser system is characterized over a wide range of amplifier duty cycles (0.1-1.0), pulse durations (50 ns-1.0 mus), peak currents (absorption spectra of nitric oxide and sulfur dioxide near 215 nm; the SO(2) spectrum was found to have significantly more structure and higher peak absorption cross sections than previously reported. PMID:18273363

  4. ESA Missions Planetary Protection Status

    NASA Astrophysics Data System (ADS)

    Kminek, Gerhard

    2016-07-01

    This presentation will report the planetary protection status of ESA flight projects with planetary protection requirements. It will cover Rosetta, Mars Express, ExoMars 2016, ExoMars 2018, JUICE, Solar Orbiter, and Bepi Colombo.

  5. Narrow-band, tunable, semiconductor-laser-based source for deep-UV absorption spectroscopy.

    PubMed

    Kliner, D A; Koplow, J P; Goldberg, L

    1997-09-15

    Tunable, narrow-bandwidth (<200-MHz), ~215-nm radiation was produced by frequency quadrupling the ~860-nm output of a high-power, pulsed GaAlAs tapered amplifier seeded by an external-cavity diode laser. Pulsing the amplifier increased the 860 nm?215 nm conversion efficiency by 2 orders of magnitude with respect to cw operation. Detection of nitric oxide and sulfur dioxide by high-resolution absorption spectroscopy was demonstrated. PMID:18188256

  6. THE 217.5 nm BAND, INFRARED ABSORPTION, AND INFRARED EMISSION FEATURES IN HYDROGENATED AMORPHOUS CARBON NANOPARTICLES

    SciTech Connect

    Duley, W. W.; Hu, Anming E-mail: a2hu@uwaterloo.ca

    2012-12-20

    We report on the preparation of hydrogenated amorphous carbon nanoparticles whose spectral characteristics include an absorption band at 217.5 nm with the profile and characteristics of the interstellar 217.5 nm feature. Vibrational spectra of these particles also contain the features commonly observed in absorption and emission from dust in the diffuse interstellar medium. These materials are produced under ''slow'' deposition conditions by minimizing the flux of incident carbon atoms and by reducing surface mobility. The initial chemistry leads to the formation of carbon chains, together with a limited range of small aromatic ring molecules, and eventually results in carbon nanoparticles having an sp {sup 2}/sp {sup 3} ratio Almost-Equal-To 0.4. Spectroscopic analysis of particle composition indicates that naphthalene and naphthalene derivatives are important constituents of this material. We suggest that carbon nanoparticles with similar composition are responsible for the appearance of the interstellar 217.5 nm band and outline how these particles can form in situ under diffuse cloud conditions by deposition of carbon on the surface of silicate grains. Spectral data from carbon nanoparticles formed under these conditions accurately reproduce IR emission spectra from a number of Galactic sources. We provide the first detailed fits to observational spectra of Type A and B emission sources based entirely on measured spectra of a carbonaceous material that can be produced in the laboratory.

  7. Fluorinated graphene oxide for enhanced S and X-band microwave absorption

    NASA Astrophysics Data System (ADS)

    Sudeep, P. M.; Vinayasree, S.; Mohanan, P.; Ajayan, P. M.; Narayanan, T. N.; Anantharaman, M. R.

    2015-06-01

    Here we report the microwave absorbing properties of three graphene derivatives, namely, graphene oxide (GO), fluorinated GO (FGO, containing 5.6 at. % Fluorine (F)), and highly FGO (HFGO, containing 23 at. % F). FGO is known to be exhibiting improved electrochemical and electronic properties when compared to GO. Fluorination modifies the dielectric properties of GO and hence thought of as a good microwave absorber. The dielectric permittivities of GO, FGO, and HFGO were estimated in the S (2 GHz to 4 GHz) and X (8 GHz to 12 GHz) bands by employing cavity perturbation technique. For this, suspensions containing GO/FGO/HFGO were made in N-Methyl Pyrrolidone (NMP) and were subjected to cavity perturbation. The reflection loss was then estimated and it was found that -37 dB (at 3.2 GHz with 6.5 mm thickness) and -31 dB (at 2.8 GHz with 6 mm thickness) in the S band and a reflection loss of -18 dB (at 8.4 GHz with 2.5 mm thickness) and -10 dB (at 11 GHz with 2 mm thickness) in the X band were achieved for 0.01 wt. % of FGO and HFGO in NMP, respectively, suggesting that these materials can serve as efficient microwave absorbers even at low concentrations.

  8. Spectroscopic determination of leaf biochemistry using band-depth analysis of absorption features and stepwise multiple linear regression

    USGS Publications Warehouse

    Kokaly, R.F.; Clark, R.N.

    1999-01-01

    We develop a new method for estimating the biochemistry of plant material using spectroscopy. Normalized band depths calculated from the continuum-removed reflectance spectra of dried and ground leaves were used to estimate their concentrations of nitrogen, lignin, and cellulose. Stepwise multiple linear regression was used to select wavelengths in the broad absorption features centered at 1.73 ??m, 2.10 ??m, and 2.30 ??m that were highly correlated with the chemistry of samples from eastern U.S. forests. Band depths of absorption features at these wavelengths were found to also be highly correlated with the chemistry of four other sites. A subset of data from the eastern U.S. forest sites was used to derive linear equations that were applied to the remaining data to successfully estimate their nitrogen, lignin, and cellulose concentrations. Correlations were highest for nitrogen (R2 from 0.75 to 0.94). The consistent results indicate the possibility of establishing a single equation capable of estimating the chemical concentrations in a wide variety of species from the reflectance spectra of dried leaves. The extension of this method to remote sensing was investigated. The effects of leaf water content, sensor signal-to-noise and bandpass, atmospheric effects, and background soil exposure were examined. Leaf water was found to be the greatest challenge to extending this empirical method to the analysis of fresh whole leaves and complete vegetation canopies. The influence of leaf water on reflectance spectra must be removed to within 10%. Other effects were reduced by continuum removal and normalization of band depths. If the effects of leaf water can be compensated for, it might be possible to extend this method to remote sensing data acquired by imaging spectrometers to give estimates of nitrogen, lignin, and cellulose concentrations over large areas for use in ecosystem studies.We develop a new method for estimating the biochemistry of plant material using

  9. Infrared, visible and ultraviolet absorptions of transition metal doped ZnS crystals with spin-polarized bands

    SciTech Connect

    Zhang, J.H.; Ding, J.W.; Cao, J.X.; Zhang, Y.L.

    2011-03-15

    The formation energies, electronic structures and optical properties of TM:ZnS systems (TM=Cr{sup 2+}, Mn{sup 2+}, Fe{sup 2+}, Co{sup 2+} and Ni{sup 2+}) are investigated by using the first principles method. It is found that the wurtzite and zinc-blende structures have about the same stability, and thus can coexist in the TM:ZnS system. From the wurtzite TM:ZnS, especially, a partially filled intermediate band (IB) is obtained at TM=Cr{sup 2+}, Ni{sup 2+} and Fe{sup 2+}, while it is absent at TM=Mn{sup 2+} and Co{sup 2+}. The additional absorptions are obtained in infrared, visible and ultraviolet (UV) regions, due to the completely spin-polarized IB at Fermi level. The results are very helpful for both the designs and applications of TM:ZnS opto-electronics devices, such as solar-cell prototype. -- Graphical abstract: Absorption coefficients of w-TM{sub x}Zn{sub 1-x}S crystals (TM=Cr{sup 2+}, Mn{sup 2+}, Fe{sup 2+}, Co{sup 2+} and Ni{sup 2+}) at x=0.028. The results may be helpful for the design and applications of TM:ZnS devices, especially for the new high efficiency solar-cell prototype, UV detector and UV LEDs. Display Omitted Research highlights: > It is found that the wurtzite and zinc-blende structures can coexist in TM:ZnS. > An intermediate band is obtained in TM:ZnS at TM=Cr{sup 2+}, Ni{sup 2+} and Fe{sup 2+}. > The absorption coefficients are obtained in infrared, visible and ultraviolet regions.

  10. On the sub-band gap optical absorption in heat treated cadmium sulphide thin film deposited on glass by chemical bath deposition technique

    SciTech Connect

    Chattopadhyay, P.; Karim, B.; Guha Roy, S.

    2013-12-28

    The sub-band gap optical absorption in chemical bath deposited cadmium sulphide thin films annealed at different temperatures has been critically analyzed with special reference to Urbach relation. It has been found that the absorption co-efficient of the material in the sub-band gap region is nearly constant up to a certain critical value of the photon energy. However, as the photon energy exceeds the critical value, the absorption coefficient increases exponentially indicating the dominance of Urbach rule. The absorption coefficients in the constant absorption region and the Urbach region have been found to be sensitive to annealing temperature. A critical examination of the temperature dependence of the absorption coefficient indicates two different kinds of optical transitions to be operative in the sub-band gap region. After a careful analyses of SEM images, energy dispersive x-ray spectra, and the dc current-voltage characteristics, we conclude that the absorption spectra in the sub-band gap domain is possibly associated with optical transition processes involving deep levels and the grain boundary states of the material.

  11. Characterization of NH overtone and combination bands in the near-infrared absorption spectra of simple cyclic imides

    NASA Astrophysics Data System (ADS)

    McNeilly, Patrick J.; Andrea, Tariq A.; Krikorian, S. Edward

    1992-10-01

    Bands due to overtone and combination vibrational modes attributable to the imide grouping have been elucidated in the near-IR absorption spectra of small-ring cyclic imides, in which the grouping is in a cis, cis conformation. The spectra closely parallel the spectra of cis lactams except that two combination modes involving the carbonyl stretching fundamental, [ν(NH) + ν(CO)] and [2ν(C=O) + imide III], occur at higher wavenumbers in the imide spectra, reflecting the higher frequency at which this fundamental absorbs. This same factor results in a reversal in the wavenumber positions of the [2ν(CO) + imide III] and [ν(NH) + imide III] combination bands in the imide spectra relative to those in the lactam spectra. In addition, in-phase and out-of-phase vibrational coupling between the two carbonyl groups in the imides may compound the band due to the [ν(NH) + ν(CO)] combination mode. These three spectral characteristics serve to distinguish the imides from the lactams in the near-IR.

  12. Fluorinated graphene oxide for enhanced S and X-band microwave absorption

    SciTech Connect

    Sudeep, P. M.; Vinayasree, S.; Mohanan, P.; Ajayan, P. M.; Narayanan, T. N.; Anantharaman, M. R.

    2015-06-01

    Here we report the microwave absorbing properties of three graphene derivatives, namely, graphene oxide (GO), fluorinated GO (FGO, containing 5.6 at. % Fluorine (F)), and highly FGO (HFGO, containing 23 at. % F). FGO is known to be exhibiting improved electrochemical and electronic properties when compared to GO. Fluorination modifies the dielectric properties of GO and hence thought of as a good microwave absorber. The dielectric permittivities of GO, FGO, and HFGO were estimated in the S (2 GHz to 4 GHz) and X (8 GHz to 12 GHz) bands by employing cavity perturbation technique. For this, suspensions containing GO/FGO/HFGO were made in N-Methyl Pyrrolidone (NMP) and were subjected to cavity perturbation. The reflection loss was then estimated and it was found that −37 dB (at 3.2 GHz with 6.5 mm thickness) and −31 dB (at 2.8 GHz with 6 mm thickness) in the S band and a reflection loss of −18 dB (at 8.4 GHz with 2.5 mm thickness) and −10 dB (at 11 GHz with 2 mm thickness) in the X band were achieved for 0.01 wt. % of FGO and HFGO in NMP, respectively, suggesting that these materials can serve as efficient microwave absorbers even at low concentrations.

  13. Multilayer Cloud Detection with the MODIS Near-Infrared Water Vapor Absorption Band

    NASA Technical Reports Server (NTRS)

    Wind, Galina; Platnick, Steven; King, Michael D.; Hubanks, Paul A,; Pavolonis, Michael J.; Heidinger, Andrew K.; Yang, Ping; Baum, Bryan A.

    2009-01-01

    Data Collection 5 processing for the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the NASA Earth Observing System EOS Terra and Aqua spacecraft includes an algorithm for detecting multilayered clouds in daytime. The main objective of this algorithm is to detect multilayered cloud scenes, specifically optically thin ice cloud overlying a lower-level water cloud, that presents difficulties for retrieving cloud effective radius using single layer plane-parallel cloud models. The algorithm uses the MODIS 0.94 micron water vapor band along with CO2 bands to obtain two above-cloud precipitable water retrievals, the difference of which, in conjunction with additional tests, provides a map of where multilayered clouds might potentially exist. The presence of a multilayered cloud results in a large difference in retrievals of above-cloud properties between the CO2 and the 0.94 micron methods. In this paper the MODIS multilayered cloud algorithm is described, results of using the algorithm over example scenes are shown, and global statistics for multilayered clouds as observed by MODIS are discussed. A theoretical study of the algorithm behavior for simulated multilayered clouds is also given. Results are compared to two other comparable passive imager methods. A set of standard cloudy atmospheric profiles developed during the course of this investigation is also presented. The results lead to the conclusion that the MODIS multilayer cloud detection algorithm has some skill in identifying multilayered clouds with different thermodynamic phases

  14. Jupiter's atmospheric composition and cloud structure deduced from absorption bands in reflected sunlight

    NASA Technical Reports Server (NTRS)

    Sato, M.; Hansen, J. E.

    1979-01-01

    The spectrum of sunlight reflected by Jupiter is analyzed by comparing observations of Woodman (1979) with multiple-scattering computations. The analysis yields information on the vertical cloud structure at several latitudes and on the abundance of CH4 and NH3 in the atmosphere of Jupiter. The abundances of CH4 and NH3 suggest that all ices and rocks are overabundant on Jupiter by a factor of 2 or more, providing an important constraint on models for the formation of Jupiter from the primitive solar nebula. The pressure level of the clouds, the gaseous NH3 abundance, the mean temperature profile, and the Clausius-Clapeyron relation suggest that these clouds are predominantly ammonia crystals with the cloud bottom at 600-700 mb. A diffuse distribution of aerosols exists between 150 and 500 mb, and the spectral variation of albedo reflects a changing bulk absorption coefficient of the material composing the aerosols and is diagnostic of the aerosol composition.

  15. Transient magneto-photoinduced absorption study of singlet fission in low band gap copolymers

    NASA Astrophysics Data System (ADS)

    Huynh, Uyen; Vardeny, Z. Valy

    2015-03-01

    We have observed the existence of singlet fission in thin films of low band gap (LBG) copolymers, PDTP-DFBT and PTB7, using the ultrafast optical pump/probe spectroscopy, probed at the energy range from IR to MIR. The singlet fission is the dissociation of a singlet exciton into two triplets through an intermediate triplet pair state (TT pair) in an overall singlet configuration; in the studied copolymers, it was observed to be very fast, in femtosecond time domain. The intermediate TT state, which dissociates into two separated triplets at later time, or recombines to the ground state appears instantaneously with the singlet exciton formation using our laser system that has ~ 150 fs time resolution. The interplay between the rate of singlet fission into sTT pairs, triplet fusion back to singlet excitons and relaxation between the TT spin sublevels explains the obtained opposite pattern of the transient magnetic field response on the dynamics of singlet excitons and TT pairs.

  16. Depolarisation of light scattered by disperse systems of low-dimensional potassium polytitanate nanoparticles in the fundamental absorption band

    SciTech Connect

    Zimnyakov, D A; Yuvchenko, S A; Pravdin, A B; Kochubey, V I; Gorokhovsky, A V; Tretyachenko, E V; Kunitsky, A I

    2014-07-31

    The results of experimental studies of depolarising properties of disperse systems on the basis of potassium polytitanate nanoplatelets and nanoribbons in the visible and near-UV spectral regions are presented. It is shown that in the fundamental absorption band of the nanoparticle material the increase in the depolarisation factor takes place for the radiation scattered perpendicularly to the direction of the probing beam. For nanoribbons a pronounced peak of depolarisation is observed, which is caused by the essential anisotropy of the particles shape and the peculiarities of the behaviour of the material dielectric function. The empirical data are compared with the theoretical results for 'nanodiscs' and 'nanoneedles' with the model dielectric function, corresponding to that obtained from optical constants of the titanium dioxide dielectric function. (laser biophotonics)

  17. Preparation of Ni-B Coating on Carbonyl Iron and Its Microwave Absorption Properties in the X Band

    NASA Astrophysics Data System (ADS)

    Li, Rong; Zhou, Wan-Cheng; Qing, Yu-Chang

    2014-09-01

    Ni-B coated carbonyl iron particles (CI@Ni-B) are prepared by the electroless plating technique. The structure, morphology, and antioxidant properties of the CI@Ni-B particles are analyzed. The results demonstrate that the CI particles have been coated with intact spherical-shell Ni-B coating, indicating the core-shell structure of CI@Ni-B particles, and the Ni-B coating can prevent the further oxidation of the CI particles. Compared with the raw CI particles/paraffin coatings with the same coating thickness of 2.0 mm and particles content of 70%, the CI@Ni-B particles/paraffin coatings possess higher microwave absorption (the RL exceeding -10 dB is obtained in the whole X band (8.2-12.4 GHz) with minimal RL of -35.0 dB at 9.2 GHz).

  18. Infrared absorption band and vibronic structure of the nitrogen-vacancy center in diamond

    NASA Astrophysics Data System (ADS)

    Kehayias, P.; Doherty, M. W.; English, D.; Fischer, R.; Jarmola, A.; Jensen, K.; Leefer, N.; Hemmer, P.; Manson, N. B.; Budker, D.

    2013-10-01

    Negatively charged nitrogen-vacancy (NV-) color centers in diamond have generated much interest for use in quantum technology. Despite the progress made in developing their applications, many questions about the basic properties of NV- centers remain unresolved. Understanding these properties can validate theoretical models of NV-, improve their use in applications, and support their development into competitive quantum devices. In particular, knowledge of the phonon modes of the 1A1 electronic state is key for understanding the optical pumping process. Using pump-probe spectroscopy, we measured the phonon sideband of the 1E→1A1 electronic transition in the NV- center. From this we calculated the 1E→1A1 one-phonon absorption spectrum and found it to differ from that of the 3E→3A2 transition, a result which is not anticipated by previous group-theoretical models of the NV- electronic states. We identified a high-energy 169-meV localized phonon mode of the 1A1 level.

  19. Future ESA Missions in Biology

    NASA Astrophysics Data System (ADS)

    Bonting, Sjoerd L.

    1984-12-01

    A survey is given of the life sciences research program sponsored by the European Space Agency (ESA). This program rests on a number of facilities originated by ESA: Spacelab, Space sled, Biorack, Anthrorack, Eureca and its Botany — and Protein Crystallization facilities. They are all to be brough into space and returned by one of the NASA Space Shuttles. With these facilities a wide range of space biology research will be covered: cell biology, developmental biology, botany, human physiology, radio-biology, exobiology and biotechnology. Information is given on how to prepare, submit and execute an experiment proposal.

  20. Intervalence-Band Absorption Saturation And Optically Induced Damage Of GaAs By Pulsed CO2 Laser Radiation

    NASA Astrophysics Data System (ADS)

    James, R. B.; Christie, W. H.; Eby, R. E.; Darken, L. S.; Mills, B. E.

    1985-11-01

    The absorption of CO2, laser radiation in p-type GaAs is dominated by direct free-hole transitions between states in the heavy- and light-hole bands. For laser intensities on the order of 10 MW/cm2, the absorption associated with these transitions in moderately Zn-doped GaAs begins to saturate in a manner predicted by an inhomogeneously broadened two-level model. For heavily Zn-doped samples (>1018 cm -3), large areas of the surface are found to melt at comparable laser energy densities, in contrast to the lightly doped samples in which the damage initially occurs in small localized sites. As the energy density of the CO2 laser radiation is progressively increased, the surface topography of the samples shows signs of ripple patterns, high local stress, vaporization of material, and exfoliation of solid GaAs fragments. X-ray emission data taken on the laser-melted samples show that there is a loss of As, compared to Ga, from the surface during the high temperature cycling. Secondary ion mass spectrometry (SIMS) measurements are used to study the diffusion of oxygen from the native oxide and the incorporation of trapped oxygen in the near-surface region of the GaAs samples that have been melted by a CO2 laser pulse. We find that oxygen trapping does occur, and that the amount and depth of the oxygen signal depends on the laser energy density and number of laser shots.

  1. Photodissociation of water in the first absorption band: A prototype for dissociation on a repulsive potential energy surface

    SciTech Connect

    Engel, V.; Staemmler, V.; Vander Wal, R.L.; Crim, F.F.

    1992-04-16

    The photodissociation of water in the first absorption band, H{sub 2}O(X) + {Dirac_h}{omega} {yields} H{sub 2}O(A{sup 1}B{sub 1}) {yields} H({sup 2}S) + OH({sup 2}II), is a prototype of fast and direct bond rupture in an excited electronic state. It has been investigated from several perspectives-absorption spectrum, final state distributions of the products, dissociation of vibrationally excited states, isotope effects, and emission spectroscopy. The availability of a calculated potential energy surface for the A state, including all three internal degrees of freedom, allows comparison of all experimental data with the results of rigorous quantum mechanical calculations without any fitting parameters or simplifying model assumptions. As the result of the confluence of ab initio electronic structure theory, dynamical theory, and experiment, water is probably the best studied and best understood polyatomic photodissociation system. In this article we review the joint experimental and theoretical advances which make water a unique system for studying molecular dynamics in excited electronic states. We focus our attention especially on the interrelation between the various perspectives and the correlation with the characteristic features of the upper-state potential energy surface. 80 refs., 14 figs.

  2. Ultrafast Time-Resolved Emission and Absorption Spectra of meso-Pyridyl Porphyrins upon Soret Band Excitation Studied by Fluorescence Up-Conversion and Transient Absorption Spectroscopy.

    PubMed

    Venkatesh, Yeduru; Venkatesan, M; Ramakrishna, B; Bangal, Prakriti Ranjan

    2016-09-01

    A comprehensive study of ultrafast molecular relaxation processes of isomeric meso-(pyridyl) porphyrins (TpyPs) has been carried out by using femtosecond time-resolved emission and absorption spectroscopic techniques upon pumping at 400 nm, Soret band (B band or S2), in 4:1 dichloromethane (DCM) and tetrahydrofuran (THF) solvent mixture. By combined studies of fluorescence up-conversion, time-correlated single photon counting, and transient absorption spectroscopic techniques, a complete model with different microscopic rate constants associated with elementary processes involved in electronic manifolds has been reported. Besides, a distinct coherent nuclear wave packet motion in Qy state is observed at low-frequency mode, ca. 26 cm(-1) region. Fluorescence up-conversion studies constitute ultrafast time-resolved emission spectra (TRES) over the whole emission range (430-710 nm) starting from S2 state to Qx state via Qy state. Careful analysis of time profiles of up-converted signals at different emission wavelengths helps to reveal detail molecular dynamics. The observed lifetimes are as indicated: A very fast decay component with 80 ± 20 fs observed at ∼435 nm is assigned to the lifetime of S2 (B) state, whereas being a rise component in the region of between 550 and 710 nm emission wavelength pertaining to Qy and Qx states, it is attributed to very fast internal conversion (IC) occurring from B → Qy and B → Qx as well. Two distinct components of Qy emission decay with ∼200-300 fs and ∼1-1.5 ps time constants are due to intramolecular vibrational redistribution (IVR) induced by solute-solvent inelastic collisions and vibrational redistribution induced by solute-solvent elastic collision, respectively. The weighted average of these two decay components is assigned as the characteristic lifetime of Qy, and it ranges between 0.3 and 0.5 ps. An additional ∼20 ± 2 ps rise component is observed in Qx emission, and it is assigned to the formation time of

  3. The Fundamental Quadrupole Band of (14)N2: Line Positions from High-Resolution Stratospheric Solar Absorption Spectra

    NASA Technical Reports Server (NTRS)

    Rinsland, C. P.; Zander, R.; Goldman, A.; Murcray, F. J.; Murcray, D. G.; Grunson, M. R.; Farmer, C. B.

    1991-01-01

    The purpose of this note is to report accurate measurements of the positions of O- and S-branch lines of the (1-0) vibration-rotation quadrupole band of molecular nitrogen ((14)N2) and improved Dunham coefficients derived from a simultaneous least-squares analysis of these measurements and selected infrared and far infrared data taken from the literature. The new measurements have been derived from stratospheric solar occultation spectra recorded with Fourier transform spectrometer (FTS) instruments operated at unapodized spectral resolutions of 0.002 and 0.01 /cm. The motivation for the present investigation is the need for improved N2 line parameters for use in IR atmospheric remote sensing investigations. The S branch of the N2 (1-0) quadrupole band is ideal for calibrating the line-of-sight airmasses of atmospheric spectra since the strongest lines are well placed in an atmospheric window, their absorption is relatively insensitive to temperature and is moderately strong (typical line center depths of 10 to 50% in high-resolution ground-based solar spectra and in lower stratospheric solar occultation spectra), and the volume mixing ratio of nitrogen is constant in the atmosphere and well known. However, a recent investigation has'shown the need to improve the accuracies of the N2 fine positions, intensities, air-broadened half-widths, and their temperature dependences to fully exploit this calibration capability (1). The present investigation addresses the problem of improving the accuracy of the N2 line positions.

  4. Nonlinear polarization spectroscopy in the frequency domain of light-harvesting complex II: absorption band substructure and exciton dynamics.

    PubMed Central

    Lokstein, H; Leupold, D; Voigt, B; Nowak, F; Ehlert, J; Hoffmann, P; Garab, G

    1995-01-01

    Spectral substructure and ultrafast excitation dynamics have been investigated in the chlorophyll (Chl) a and b Qy region of isolated plant light-harvesting complex II (LHC II). We demonstrate the feasibility of Nonlinear Polarization Spectroscopy in the frequency domain, a novel photosynthesis research laser spectroscopic technique, to determine not only ultrafast population relaxation (T1) and dephasing (T2) times, but also to reveal the complex spectral substructure in the Qy band as well as the mode(s) of absorption band broadening at room temperature (RT). The study gives further direct evidence for the existence of up to now hypothetical "Chl forms". Of particular interest is the differentiated participation of the Chl forms in energy transfer in trimeric and aggregated LHC II. Limits for T2 are given in the range of a few ten fs. Inhomogeneous broadening does not exceed the homogeneous widths of the subbands at RT. The implications of the results for the energy transfer mechanisms in the antenna are discussed. PMID:8534824

  5. Visible-band (390-940nm) monitoring of the Pluto absorption spectrum during the New Horizons encounter

    NASA Astrophysics Data System (ADS)

    Smith, Robert J.; Marchant, Jonathan M.

    2015-11-01

    Whilst Earth-based observations obviously cannot compete with New Horizons’ on-board instrumentation in most regards, the New Horizons data set is essentially a snapshot of Pluto in July 2015. The New Horizons project team therefore coordinated a broad international observing campaign to provide temporal context and to take advantage of the once-in-a-lifetime opportunity to directly link our Earth-based view of Pluto with “ground truth” provided by in situ measurements. This both adds value to existing archival data sets and forms the basis of long term, monitoring as we watch Pluto recede from the Sun over the coming years. We present visible-band (390-940nm) monitoring of the Pluto absorption spectrum over the period July - October 2015 from the Liverpool Telescope (LT). In particular we wished to understand the well-known 6-day fluctuation in the methane ice absorption spectrum which is observable from Earth in relation to the never-before-available high resolution maps of the Pluto surface. The LT is a fully robotic 2.0m optical telescope that automatically and dynamically schedules observations across 30+ observing programmes with a broad instrument suite. It is ideal for both reactive response to dynamic events (such as the fly-by) and long term, stable monitoring with timing constraints individually optimised to the science requirements of each programme. For example past studies of the observed CH4 absorption variability have yielded ambiguity of whether they were caused by real physical changes or geometric observation constraints, in large part because of the uneven time sampling imposed by traditional telescope scheduling.

  6. Transition state region in the A-Band photodissociation of allyl iodide—A femtosecond extreme ultraviolet transient absorption study

    NASA Astrophysics Data System (ADS)

    Bhattacherjee, Aditi; Attar, Andrew R.; Leone, Stephen R.

    2016-03-01

    Femtosecond extreme ultraviolet (XUV) transient absorption spectroscopy based on a high-harmonic generation source is used to study the 266 nm induced A-band photodissociation dynamics of allyl iodide (CH2 =CHCH2I). The photolysis of the C—I bond at this wavelength produces iodine atoms both in the ground (2P3/2, I) and spin-orbit excited (2P1/2, I*) states, with the latter as the predominant channel. Using XUV absorption at the iodine N4/5 edge (45-60 eV), the experiments constitute a direct probe of not only the long-lived atomic iodine reaction products but also the fleeting transition state region of the repulsive nIσ∗C—I excited states. Specifically, three distinct features are identified in the XUV transient absorption spectrum at 45.3 eV, 47.4 eV, and 48.4 eV (denoted transients A, B, and C, respectively), which arise from the repulsive valence-excited nσ∗ states and project onto the high-lying core-excited states of the dissociating molecule via excitation of 4d(I) core electrons. Transients A and B originate from 4d(I) → n(I) core-to-valence transitions, whereas transient C is best assigned to a 4d(I) →σ∗(C—I) transition. The measured differential absorbance of these new features along with the I/I* branching ratios known from the literature is used to suggest a more definitive assignment, albeit provisional, of the transients to specific dissociative states within the A-band manifold. The transients are found to peak around 55 fs-65 fs and decay completely by 145 fs-185 fs, demonstrating the ability of XUV spectroscopy to map the evolution of reactants into products in real time. The similarity in the energies of transients A and B with analogous features observed in methyl iodide [Attar et al. J. Phys. Chem. Lett. 6, 5072, (2015)] together with the new observation of transient C in the present work provides a more complete picture of the valence electronic structure in the transition state region. The results provide a benchmark for

  7. Towards monitoring of geohazards with ESA's Sentinel-1 C-band SAR data: nationwide feasibility mapping over Great Britain calibrated using ERS-1/2 and ENVISAT PSI data

    NASA Astrophysics Data System (ADS)

    Cigna, Francesca; Bateson, Luke; Dashwood, Claire; Jordan, Colm

    2013-04-01

    Following the success of its predecessors ERS-1/2 and ENVISAT, ESA's Sentinel-1 constellation will provide routine, free of charge and globally-available Synthetic Aperture Radar (SAR) observations of the Earth's surface starting in 2013, with 12day repeat cycle and up to 5m spatial resolution. The upcoming availability of this unprecedented and long-term radar-based observation capacity is stimulating new scientific and operational perspectives within the geohazards and land monitoring community, who initiated and is being working on target preparatory studies to exploit this attractive and rich reservoir of SAR data for, among others, interferometric applications. The Earth and Planetary Observation and Monitoring, and the Shallow Geohazards and Risks Teams of the British Geological Survey (BGS) are routinely assessing new technologies for geohazard mapping, and carrying out innovative research to improve the understanding of landslide processes and their dynamics. Building upon the successful achievements of recent applications of Persistent Scatterer Interferometry (PSI) to geohazards mapping and monitoring in Europe, and with the aim of enhancing further the research on radar EO for landslide management in Britain, since the beginning of 2012 the BGS has been carrying out a research project funded by internal NERC grants aimed at evaluating the potential of these techniques to better understand landslide processes over Great Britain. We mapped the PSI feasibility over the entire landmass, based on the combination of topographic and landuse effects which were modelled by using medium to high resolution DEMs, land cover information from the EEA CORINE Land Cover map 2006, and six PSI datasets over London, Stoke-on-Trent, Bristol/Bath, and the Northumberland-Durham region, made available to BGS through the projects ESA-GMES Terrafirma and EC-FP7 PanGeo. The feasibility maps for the ERS-1/2 and ENVISAT ascending and descending modes showed that topography is not

  8. Collision-Induced Absorption by H2 Pairs in the Second Overtone Band at 298 and 77.5 K: Comparison between Experimental and Theoretical Results

    NASA Technical Reports Server (NTRS)

    Brodbeck, C.; Bouanich, J.-P.; van-Thanh, Nguyen; Fu, Y.; Borysow, A.

    1999-01-01

    The collision-induced spectra of hydrogen in the region of the second overtone at 0.8 microns have been recorded at temperatures of 298 and 77.5 K and for gas densities ranging from 100 to 800 amagats. The spectral profile defined by the absorption coefficient per squared density varies significantly with the density, so that the binary absorption coefficient has been determined by extrapolations to zero density of the measured profiles. Our extrapolated measurements and our recent ab initio quantum calculation are in relatively good agreement with one another. Taking into account the very weak absorption of the second overtone band, the agreement is, however, not as good as it has become (our) standard for strong bands.

  9. Estimation of variability of specific absorption rate with physical description of children exposed to electromagnetic field in the VHF band.

    PubMed

    Nagaoka, T; Watanabe, S

    2009-01-01

    Recently, there has been an increasing concern regarding the effects of electromagnetic waves on the health of humans. The safety of radio frequency electromagnetic fields (RF-EMFs) is evaluated by the specific absorption rate (SAR). In recent years, SAR has been estimated by numerical simulation using fine-resolution and anatomically realistic reference whole-body voxel models of people of various ages. The variation in SAR with a change in the physical features of a real person is hardly studied, although every person has different physical features. In this study, in order to estimate the individual variability in SAR of persons, we obtained considerable 3D body shape data from actual three-year-old children and developed several homogeneous models of these children. The variability in SAR of the homogeneous models of three-year-old children for whole-body exposure to RF electromagnetic fields in the very high frequency (VHF) band calculated using the finite-difference time-domain method has been described. PMID:19964253

  10. Microwave-assisted synthesis of graphene-Ni composites with enhanced microwave absorption properties in Ku-band

    NASA Astrophysics Data System (ADS)

    Zhu, Zetao; Sun, Xin; Li, Guoxian; Xue, Hairong; Guo, Hu; Fan, Xiaoli; Pan, Xuchen; He, Jianping

    2015-03-01

    Recently, graphene has been applied as a new microwave absorber because of its high dielectric loss and low density. Nevertheless, the high dielectric constant of pristine graphene has caused unbalanced electromagnetic parameters and results in a bad impedance matching characteristic. In this study, we report a facile microwave-assisted heating approach to produce reduced graphene oxide-nickel (RGO-Ni) composites. The phase and morphology of as-synthesized RGO-Ni composites are characterized by XRD, Raman, FESEM and TEM. The results show that Ni nanoparticles with a diameter around 20 nm are grown densely and uniformly on the RGO sheets. In addition, enhanced microwave absorption properties in Ku-band of RGO-Ni composites is mainly due to the synergistic effect of dielectric loss and magnetic loss and the dramatically electron polarizations caused by the formation of large conductive network. The minimum reflection loss of RGO-Ni-2 composite with the thickness of 2 mm can reaches -42 dB at 17.6 GHz. The RGO-Ni composite is an attractive candidate for the new type of high performance microwave absorbing material.

  11. High resolution absorption cross sections in the transmission window region of the Schumann-Runge bands and Herzberg continuum of O2

    NASA Technical Reports Server (NTRS)

    Yoshino, K.; Esmond, J. R.; Cheung, A. S.-C.; Freeman, D. E.; Parkinson, W. H.

    1992-01-01

    Results are presented on measurements, conducted in the wavelength region 180-195 nm, and at different pressures of oxygen (between 2.5-760 torr) in order to separate the pressure-dependent absorption from the main cross sections, of the absorption cross sections of the Schumann-Runge bands in the window region between the rotational lines of S-R bands of O2. The present cross sections supersede the earlier published cross sections (Yoshino et al., 1983). The combined cross sections are presented graphically; they are available at wavenumber intervals of about 0.1/cm from the National Space Science Data Center. The Herzberg continuum cross sections are derived after subtracting calculated contributions from the Schumann-Runge bands. These are significantly smaller than any previous measurements.

  12. Analysis of Mars surface hydration through the MEx/OMEGA observation of the 3 μm absorption band.

    NASA Astrophysics Data System (ADS)

    Jouglet, D.; Poulet, F.; Bibring, J. P.; Langevin, Y.; Gondet, B.; Milliken, R. E.; Mustard, J. F.

    The near infrared Mars surface global mapping done by OMEGA gives the first opportunity to study the global and detailed characteristics of the 3µm hydration absorption band on Mars surface. This feature is indistinctly due to bending and stretching vibrations of water bound in minerals or adsorbed at their surface, and of hydroxyl groups (for a review, see e.g. [1] or [2]). Its study may give new elements to determine the geologic and climatic past of Mars, and may put new constrain about the current water cycle of Mars. OMEGA data are processed in a pipeline that converts raw data to radiance, removes atmospheric effects and gets I/F. Specific data reduction scheme has been developed to assess temperature of OMEGA spectra at 5 µm and to remove their thermal part so as to get the albedo from 1.µm to 5.1µm ([2]). Two methods, the Integrated Band Depth and the water content based on comparison with laboratory measures of Yen et al. ([3]), have been used to assess the 3µm band depth. These two methods where applied to OMEGA spectra acquired at a nominal calibration level and not exhibiting water ice features. This corresponds to approximately 35 million spectra ([2]). The data processed show the presence of this absorption feature overall the Martian surface, which could be explained by the presence of adsorbed water up to 1% water mass percentage ([4]) and by rinds or coating resulting from weathering (see e.g. [5] or [6]). A possible increase of hydration with albedo is discussed so as to discriminate between the albedo-dependence of the method and hydration variations. Terrains enriched in phyllosilicates ([7]), sulfates ([8]) or hydroxides exhibit an increased hydration at 3 µm. This terrains show that the 3 µm band can bring additional information about composition, for example by observing a variation in the shape of the band. A decrease of hydration with elevation is observed on the processed data independently of the value of albedo. This correlation

  13. ESA Venus Entry Probe Study

    NASA Technical Reports Server (NTRS)

    vandenBerg, M. L.; Falkner, P.; Phipps, A.; Underwood, J. C.; Lingard, J. S.; Moorhouse, J.; Kraft, S.; Peacock, A.

    2005-01-01

    The Venus Entry Probe is one of ESA s Technology Reference Studies (TRS). The purpose of the Technology Reference Studies is to provide a focus for the development of strategically important technologies that are of likely relevance for future scientific missions. The aim of the Venus Entry Probe TRS is to study approaches for low cost in-situ exploration of Venus and other planetary bodies with a significant atmosphere. In this paper, the mission objectives and an outline of the mission concept of the Venus Entry Probe TRS are presented.

  14. Radiative analysis of global mean temperature trends in the middle atmosphere: Effects of non-locality and secondary absorption bands

    NASA Astrophysics Data System (ADS)

    Fomichev, V. I.; Jonsson, A. I.; Ward, W. E.

    2016-02-01

    In this paper, we provide a refined and extended assignment of past and future temperature changes relative to previous analyses and describe and evaluate the relevance of vertical coupling and non-linear and secondary radiative mechanisms for the interpretation of climatic temperature variations in the middle atmosphere. Because of their nature, the latter mechanisms are not adequately accounted for in most regression analyses of temperature trends as a function of local constituent variations. These mechanisms are examined using (1) globally averaged profiles from transient simulations with the Canadian Middle Atmosphere Model (CMAM) forced by changes in greenhouse gases and ozone depleting substances and (2) a one-dimensional radiative-equilibrium model forced using the diagnosed global mean changes in radiatively active constituents as derived from the CMAM model runs. The conditions during the periods 1975 to 1995 and 2010 to 2040 (during which the rates of change in ozone and CO2 differ) provide a suitable contrast for the role of the non-linear and non-local mechanisms being evaluated in this paper to be clearly differentiated and evaluated. Vertical coupling of radiative transfer effects and the influence of secondary absorption bands are important enough to render the results of multiple linear regression analyses between the temperature response and constituent changes misleading. These effects are evaluated in detail using the 1D radiative-equilibrium model using profiles from the CMAM runs as inputs. In order to explain the differences in the CMAM temperature trends prior to and after 2000 these other radiative effects must be considered in addition to local changes in the radiatively active species. The middle atmosphere temperature cools in response to CO2 and water vapor increases, but past and future trends are modulated by ozone changes.

  15. Uncovering the mechanism for selective control of the visible and near-IR absorption bands in bacteriochlorophylls a, b and g

    PubMed Central

    Fujisawa, Jun-ichi; Nagata, Morio

    2014-01-01

    Bacteriochlorophylls (BChls) play an important role as light harvesters in photosynthetic bacteria. Interestingly, bacteriochlorophylls (BChls) a, b, and g selectively tune their visible (Qx) and near IR (Qy) absorption bands by the substituent changes. In this paper, we theoretically study the mechanism for the selective control of the absorption bands. Density functional theory (DFT) and time-dependent DFT (TD-DFT) and four-orbital model analyses reveal that the selective red-shift of the Qy band with the substituent change from BChl a to b occurs with the lower-energy shift of the (HOMO, LUMO) excited state directly induced by the molecular-orbital energy changes. In contrast, the Qx band hardly shifts by the cancellation between the higher- and lower-energy shifts of the (HOMO-1, LUMO) excited state directly induced by the molecular-orbital energy changes and configuration interaction, respectively. On the other hand, with the substituent changes from BChl a to g, the Qx band selectively blue-shifts by the larger higher-energy shift of the (HOMO-1, LUMO) excited state directly induced by the molecular-orbital energy shifts than the lower-energy shift due to the configuration interaction. In contrast, the Qy band hardly shifts by the cancellation between the higher- and lower-energy shifts of the (HOMO, LUMO) excited state directly induced by the molecular-orbital energy changes and configuration interaction, respectively. Our work provides the important knowledge for understanding how nature controls the light-absorption properties of the BChl dyes, which might be also useful for design of porphyrinoid chromophores. PMID:27493495

  16. Strong heavy-to-light hole intersubband absorption in the valence band of carbon-doped GaAs/AlAs superlattices

    NASA Astrophysics Data System (ADS)

    Hossain, M. I.; Ikonic, Z.; Watson, J.; Shao, J.; Harrison, P.; Manfra, M. J.; Malis, O.

    2013-02-01

    We report strong mid-infrared absorption of in-plane polarized light due to heavy-to-light hole intersubband transitions in the valence band of C-doped GaAs quantum wells with AlAs barriers. The transition energies are well reproduced by theoretical calculations including layer inter-diffusion. The inter-diffusion length was estimated to be 8 ± 2 Å, a value that is consistent with electron microscopy measurements. These results highlight the importance of modeling the nanoscale structure of the semiconductors for accurately reproducing intra-band transition energies of heavy carriers such as the holes.

  17. Ozone profile retrievals from the ESA GOME instrument

    NASA Technical Reports Server (NTRS)

    Munro, Rosemary; Kerridge, Brian J.; Burrows, John P.; Chance, Kelly

    1994-01-01

    The potential of the ESA Global Ozone Monitoring Experiment (GOME) to produce ozone profile information has been examined by carrying out two sample retrievals using simulated GOME data. The first retrieval examines the potential of the GOME instrument to produce stratospheric ozone profiles using the traditional back-scatter ultraviolet technique, while the second examines the possibility of obtaining tropospheric profile information, and improving the quality of the stratospheric profile retrievals, by exploiting the temperature dependence of the ozone Huggins bands.

  18. ESA announces its Future Science Missions

    NASA Astrophysics Data System (ADS)

    2000-10-01

    The announcement will be made at ESA's Head Office, 8-10 rue Mario Nikis in Paris, during a press breakfast starting at 08:30. Media representatives wishing to attend the event are kindly requested to fill out the attached accreditation from and fax it back to ESA Media Relations Office - Paris. Note to editors The announcement will follow a two-day meeting of ESA's Space Science Committee (SPC), composed of Delegates from all ESA's Member States, in Paris on 11 and 12 October. The SPC will decide - on the basis of the Space Science Advisory Committee's (SSAC) recommendations formulated earlier in September - about the next Cornerstone (CS) and Flexi (F) Missions that will be implemented in the framework of ESA's Horizons 2000 Programme. Further information about the Future Mission candidates and the ESA Science Programme can be found at: http://sci.esa.int. In particular the SSAC recommendations to SPC can be found at: http://sci.esa.int/structure/content/index.cfm?aid=1&cid=2304 Further information on ESA at : http//www.esa.int

  19. Strong interlayer coupling mediated giant two-photon absorption in MoS e2 /graphene oxide heterostructure: Quenching of exciton bands

    NASA Astrophysics Data System (ADS)

    Sharma, Rituraj; Aneesh, J.; Yadav, Rajesh Kumar; Sanda, Suresh; Barik, A. R.; Mishra, Ashish Kumar; Maji, Tuhin Kumar; Karmakar, Debjani; Adarsh, K. V.

    2016-04-01

    A complex few-layer MoS e2 /graphene oxide (GO) heterostructure with strong interlayer coupling was prepared by a facile hydrothermal method. In this strongly coupled heterostructure, we demonstrate a giant enhancement of two-photon absorption that is in stark contrast to the reverse saturable absorption of a weakly coupled MoS e2 /GO heterostructure and saturable absorption of isolated MoS e2 . Spectroscopic evidence of our study indicates that the optical signatures of isolated MoS e2 and GO domains are significantly modified in the heterostructure, displaying a direct coupling of both domains. Furthermore, our first-principles calculations indicate that strong interlayer coupling between the layers dramatically suppresses the MoS e2 excitonic bands. We envision that our findings provide a powerful tool to explore different optical functionalities as a function of interlayer coupling, which may be essential for the development of device technologies.

  20. Optical absorption and band gap reduction in (Fe1-xCrx)2O3 solid solutions: A first-principles study

    SciTech Connect

    Wang, Yong; Lopata, Kenneth A.; Chambers, Scott A.; Govind, Niranjan; Sushko, Petr V.

    2013-12-02

    We provide a detailed theoretical analysis of the character of optical transitions and band gap reduction in (Fe1-xCrx)2O3 solid solutions using extensive periodic model and embedded cluster calculations. Optical absorption bands for x = 0.0, 0.5, and 1.0 are assigned on the basis of timedependent density functional theory (TDDFT) calculations. A band-gap reduction of as much as 0.7 eV with respect to that of pure α-Fe2O3 is found. This result can be attributed to predominantly two effects: (i) the higher valence band edge for x ≈ 0.5, as compared to those in pure α-Fe2O3 and α-Cr2O3, and, (ii) the appearance of Cr  Fe d–d transitions in the solid solutions. Broadening of the valence band due to hybridization of the O 2p states with Fe and Cr 3d states also contributes to band gap reduction.

  1. A study of the structure of the ν1(HF) absorption band of the СH3СN…HF complex

    NASA Astrophysics Data System (ADS)

    Gromova, E. I.; Glazachev, E. V.; Bulychev, V. P.; Koshevarnikov, A. M.; Tokhadze, K. G.

    2015-09-01

    The ν1(HF) absorption band shape of the CH3CN…HF complex is studied in the gas phase at a temperature of 293 K. The spectra of gas mixtures CH3CN/HF are recorded in the region of 4000-3400 cm-1 at a resolution from 0.1 to 0.005 cm-1 with a Bruker IFS-120 HR vacuum Fourier spectrometer in a cell 10 cm in length with wedge-shaped sapphire windows. The procedure used to separate the residual water absorption allows more than ten fine-structure bands to be recorded on the low-frequency wing of the ν1(HF) band. It is shown that the fine structure of the band is formed primarily due to hot transitions from excited states of the low-frequency ν7 librational vibration. Geometrical parameters of the equilibrium nuclear configuration, the binding energy, and the dipole moment of the complex are determined from a sufficiently accurate quantum-chemical calculation. The frequencies and intensities for a number of spectral transitions of this complex are obtained in the harmonic approximation and from variational solutions of anharmonic vibrational problems.

  2. A laboratory Atlas of the 5 nu-1 NH3 absorption band at 6475 A with applications to Jupiter and Saturn

    NASA Technical Reports Server (NTRS)

    Giver, L. P.; Miller, J. H.; Boese, R. W.

    1975-01-01

    A complete atlas of the 5 nu-1 absorption band of NH3 is presented together with measurements of the total band intensity, line intensities, and self-broadening coefficients. The spectrum, which is displayed in the interval from 6418 to 6550 A, was obtained photoelectrically at a pressure of 0.061 atm, and many more lines were seen in this spectrum than in a previous one obtained at a pressure of 0.39 atm. The band intensity is used to derive the NH3 abundance in the atmospheres of Jupiter and Saturn, and the abundances in a single vertical path are found to be about 10 m amagat for Jupiter and 2 m amagat for Saturn. These results are shown to be in agreement with previous results obtained from higher resolution photographic spectra.

  3. Sub-gap and band edge optical absorption in a-Si:H by photothermal deflection spectroscopy

    NASA Astrophysics Data System (ADS)

    Jackson, W. B.; Amer, N. M.

    1981-07-01

    Using photothermal deflection spectroscopy, the optical absorption of various a-Si:H films was investigated in the range of 2.1 to 0.6 eV. An absorption shoulder which depends on deposition conditions and on doping was found and was attributed to dangling bonds. The exponential edge broadens with increasing spin density.

  4. Complexities in pyroxene compositions derived from absorption band centers: Examples from Apollo samples, HED meteorites, synthetic pure pyroxenes, and remote sensing data

    NASA Astrophysics Data System (ADS)

    Moriarty, D. P.; Pieters, C. M.

    2016-02-01

    We reexamine the relationship between pyroxene composition and near-infrared absorption bands, integrating measurements of diverse natural and synthetic samples. We test an algorithm (PLC) involving a two-part linear continuum removal and parabolic fits to the 1 and 2 μm bands—a computationally simple approach which can easily be automated and applied to remote sensing data. Employing a suite of synthetic pure pyroxenes, the PLC technique is shown to derive similar band centers to the modified Gaussian model. PLC analyses are extended to natural pyroxene-bearing materials, including (1) bulk lunar basalts and pyroxene separates, (2) diverse lunar soils, and (3) HED meteorites. For natural pyroxenes, the relationship between composition and absorption band center differs from that of synthetic pyroxenes. These differences arise from complexities inherent in natural materials such as exsolution, zoning, mixing, and space weathering. For these reasons, band center measurements of natural pyroxene-bearing materials are compositionally nonunique and could represent three distinct scenarios (1) pyroxene with a narrow compositional range, (2) complexly zoned pyroxene grains, or (3) a mixture of multiple pyroxene (or nonpyroxene) components. Therefore, a universal quantitative relationship between band centers and pyroxene composition cannot be uniquely derived for natural pyroxene-bearing materials without additional geologic context. Nevertheless, useful relative relationships between composition and band center persist in most cases. These relationships are used to interpret M3 data from the Humboldtianum Basin. Four distinct compositional units are identified (1) Mare Humboldtianum basalts, (2) distinct outer basalts, (3) low-Ca pyroxene-bearing materials, and (4) feldspathic materials.

  5. Clay composition and swelling potential estimation of soils using depth of absorption bands in the SWIR (1100-2500 nm) spectral domain

    NASA Astrophysics Data System (ADS)

    Dufréchou, Grégory; Granjean, Gilles; Bourguignon, Anne

    2014-05-01

    Swelling soils contain clay minerals that change volume with water content and cause extensive and expensive damage on infrastructures. Presence of clay minerals is traditionally a good estimator of soils swelling and shrinking behavior. Montmorillonite (i.e. smectite group), illite, kaolinite are the most common minerals in soils and are usually associated to high, moderate, and low swelling potential when they are present in significant amount. Characterization of swelling potential and identification of clay minerals of soils using conventional analysis are slow, expensive, and does not permit integrated measurements. SWIR (1100-2500 nm) spectral domain are characterized by significant spectral absorption bands related to clay content that can be used to recognize main clay minerals. Hyperspectral laboratory using an ASD Fieldspec Pro spectrometer provides thus a rapid and less expensive field surface sensing that permits to measure soil spectral properties. This study presents a new laboratory reflectance spectroscopy method that used depth of clay diagnostic absorption bands (1400 nm, 1900 nm, and 2200 nm) to compare natural soils to synthetic montmorillonite-illite-kaolinite mixtures. We observe in mixtures that illite, montmorillonite, and kaolinite content respectively strongly influence the depth of absorption bands at 1400 nm (D1400), 1900 nm (D1900), and 2200 nm (D2200). To attenuate or removed effects of abundance and grain size, depth of absorption bands ratios were thus used to performed (i) 3D (using D1900/D2200, D1400/D1900, and D2200/D1400 as axis), and (ii) 2D (using D1400/D1900 and D1900/D2200 as axis) diagrams of synthetic mixtures. In this case we supposed that the overall reduction or growth of depth absorption bands should be similarly affected by the abundance and grain size of materials in soil. In 3D and 2D diagrams, the mixtures define a triangular shape formed by two clay minerals as external envelop and the three clay minerals mixtures

  6. ESA uncovers Geminga's `hot spot'

    NASA Astrophysics Data System (ADS)

    2004-07-01

    16 July 2004 Astronomers using ESA’s X-ray observatory XMM-Newton have detected a small, bright ‘hot spot’ on the surface of the neutron star called Geminga, 500 light-years away. The hot spot is the size of a football field and is caused by the same mechanism producing Geminga’s X-ray tails. This discovery identifies the missing link between the X-ray and gamma-ray emission from Geminga. hi-res Size hi-res: 1284 kb Credits: ESA, P. Caraveo (IASF, Milan) Geminga's hot spot This figure shows the effects of charged particles accelerated in the magnetosphere of Geminga. Panel (a) shows an image taken with the EPIC instrument on board the XMM-Newton observatory. The bright tails, made of particles kicked out by Geminga’s strong magnetic field, trail the neutron star as it moves about in space. Panel (b) shows how electrically charged particles interact with Geminga’s magnetic field. For example, if electrons (blue) are kicked out by the star, positrons (in red) hit the star’s magnetic poles like in an ‘own goal’. Panel (c) illustrates the size of Geminga’s magnetic field (blue) compared to that of the star itself at the centre (purple). The magnetic field is tilted with respect to Geminga’s rotation axis (red). Panel (d) shows the magnetic poles of Geminga, where charged particles hit the surface of the star, creating a two-million degrees hot spot, a region much hotter than the surroundings. As the star spins on its rotation axis, the hot spot comes into view and then disappears, causing the periodic colour change seen by XMM-Newton. An animated version of the entire sequence can be found at: Click here for animated GIF [low resolution, animated GIF, 5536 KB] Click here for AVI [high resolution, AVI with DIVX compression, 19128 KB] hi-res Size hi-res: 371 kb Credits: ESA, P. Caraveo (IASF, Milan) Geminga's hot spot, panel (a) Panel (a) shows an image taken with the EPIC instrument on board the XMM-Newton observatory. The bright tails, made of

  7. 8-band k·p modelling of mid-infrared intersubband absorption in Ge quantum wells

    NASA Astrophysics Data System (ADS)

    Paul, D. J.

    2016-07-01

    The 8-band k.p parameters which include the direct band coupling between the conduction and the valence bands are derived and used to model optical intersubband transitions in Ge quantum well heterostructure material grown on Si substrates. Whilst for Si rich quantum wells the coupling between the conduction bands and valence bands is not important for accurate modelling, the present work demonstrates that the inclusion of such coupling is essential to accurately determine intersubband transitions between hole states in Ge and Ge-rich Si1-xGex quantum wells. This is due to the direct bandgap being far smaller in energy in Ge compared to Si. Compositional bowing parameters for a range of the key modelling input parameters required for Ge/SiGe heterostructures, including the Kane matrix elements, the effective mass of the Γ 2 ' conduction band, and the Dresselhaus parameters for both 6- and 8-band k.p modelling, have been determined. These have been used to understand valence band intersubband transitions in a range of Ge quantum well intersubband photodetector devices in the mid-infrared wavelength range.

  8. ESA to unveil its new science programme

    NASA Astrophysics Data System (ADS)

    2002-05-01

    The science community, European industry, the ESA Executive and cooperating space agencies in Europe and elsewhere have been consulted, and sometimes challenged, to find the best ways to maximise science value for money. The exercise is now over following intensive consultations with ESA's Space Science Advisory Committee (SSAC) and the Member States represented by the Science Programme Committee (SPC). After final SPC approval at the meeting on 22/23 May there will be a new programme and a new implementation plan. The results of this meeting will then be presented to the press on 27 May, in Paris, by the ESA Director of Science, in the presence of the chairmen of the SSAC and SPC. Media representatives wishing to attend the press breakfast are kindly requested to complete the attached reply form and fax it back to ESA Media Relations, Fax: +33.(0)1.5369.7690 For more information, please contact: ESA - Communication Department Media Relations Office Tel: +33 (0)1.53.69.71.55 Fax: +33 (0)1.53.69.76.90 ESA's Science Programme Agenda Monday 27 May 2002 - 08:30-10:00 ESA Headquarters, 8/10 rue Mario Nikis, 75015 Paris 08:30 Registration & breakfast 08:45 Introduction , by Hugo Marée, Science Programme Coordination Office 08:50 Presentation of the new ESA Science Programme, by Prof. David Southwood, ESA Director of Science 09:10 Question &Answer session

  9. The ESA Geohazard Exploitation Platform

    NASA Astrophysics Data System (ADS)

    Bally, Philippe; Laur, Henri; Mathieu, Pierre-Philippe; Pinto, Salvatore

    2015-04-01

    Earthquakes represent one of the world's most significant hazards in terms both of loss of life and damages. In the first decade of the 21st century, earthquakes accounted for 60 percent of fatalities from natural disasters, according to the United Nations International Strategy for Disaster Reduction (UNISDR). To support mitigation activities designed to assess and reduce risks and improve response in emergency situations, satellite EO can be used to provide a broad range of geo-information services. This includes for instance crustal block boundary mapping to better characterize active faults, strain rate mapping to assess how rapidly faults are deforming, soil vulnerability mapping to help estimate how the soil is behaving in reaction to seismic phenomena, geo-information to assess the extent and intensity of the earthquake impact on man-made structures and formulate assumptions on the evolution of the seismic sequence, i.e. where local aftershocks or future main shocks (on nearby faults) are most likely to occur. In May 2012, the European Space Agency and the GEO Secretariat convened the International Forum on Satellite EO for Geohazards now known as the Santorini Conference. The event was the continuation of a series of international workshops such as those organized by the Geohazards Theme of the Integrated Global Observing Strategy Partnership. In Santorini the seismic community has set out a vision of the EO contribution to an operational global seismic risk program, which lead to the Geohazard Supersites and Natural Laboratories (GSNL) initiative. The initial contribution of ESA to suuport the GSNL was the first Supersites Exploitation Platform (SSEP) system in the framework of Grid Processing On Demand (GPOD), now followed by the Geohazard Exploitation Platform (GEP). In this presentation, we will describe the contribution of the GEP for exploiting satellite EO for geohazard risk assessment. It is supporting the GEO Supersites and has been further

  10. Conduction-band electronic states of YbInCu{sub 4} studied by photoemission and soft x-ray absorption spectroscopies

    SciTech Connect

    Utsumi, Yuki; Kurihara, Hidenao; Maso, Hiroyuki; Tobimatsu, Komei; Sato, Hitoshi; Shimada, Kenya; Namatame, Hirofumi; Hiraoka, Koichi; Kojima, Kenichi; Ohkochi, Takuo; Fujimori, Shin-ichi; Takeda, Yukiharu; Saitoh, Yuji; Mimura, Kojiro; Ueda, Shigenori; Yamashita, Yoshiyuki; Yoshikawa, Hideki; Kobayashi, Keisuke; Oguchi, Tamio; Taniguchi, Masaki

    2011-09-15

    We have studied conduction-band (CB) electronic states of a typical valence-transition compound YbInCu{sub 4} by means of temperature-dependent hard x-ray photoemission spectroscopy (HX-PES) of the Cu 2p{sub 3/2} and In 3d{sub 5/2} core states taken at h{nu}=5.95 keV, soft x-ray absorption spectroscopy (XAS) of the Cu 2p{sub 3/2} core absorption region around h{nu}{approx}935 eV, and soft x-ray photoemission spectroscopy (SX-PES) of the valence band at the Cu 2p{sub 3/2} absorption edge of h{nu}=933.0 eV. With decreasing temperature below the valence transition at T{sub V}=42 K, we have found that (1) the Cu 2p{sub 3/2} and In 3d{sub 5/2} peaks in the HX-PES spectra exhibit the energy shift toward the lower binding-energy side by {approx}40 and {approx}30 meV, respectively, (2) an energy position of the Cu 2p{sub 3/2} main absorption peak in the XAS spectrum is shifted toward higher photon-energy side by {approx}100 meV, with an appearance of a shoulder structure below the Cu 2p{sub 3/2} main absorption peak, and (3) an intensity of the Cu L{sub 3}VV Auger spectrum is abruptly enhanced. These experimental results suggest that the Fermi level of the CB-derived density of states is shifted toward the lower binding-energy side. We have described the valence transition in YbInCu{sub 4} in terms of the charge transfer from the CB to Yb 4f states.

  11. The Rovibrational Intensities of Five Absorption Bands of (12)C(16)O2 Between 5218 and 5349/cm

    NASA Technical Reports Server (NTRS)

    Giver, Lawrence P.; Brown, Linda R.; Chackerian, Charles, Jr.; Freedman, Richard S.; Gore, Warren J. (Technical Monitor)

    2002-01-01

    Absolute line intensities, band intensities, and Herman-Wallis parameters were measured for the (01(sup 1)2)(sub I) from (00(sup 0)0)(sub I) perpendicular band of (12)C(16)O2 centered at 5315/cm, along with the three nearby associated hot bands: (10(sup 0)2)(sub II) from (01(sup 1)0)(sub I) at 5248/cm, (02(sup 2))(sub I) from (01(sup 1)0)(sub I) at 5291/cm, and (10(sup 0)2)(sub I) from (01(sup 1)0)(sub I) at 5349/cm. The nearby parallel hot band (30(sup 0))(sub I) from (10(sup 0)0)(sub II) at 5218/cm was also included in this study.

  12. Golden legacy from ESA's observatory

    NASA Astrophysics Data System (ADS)

    2003-07-01

    'milestone number' of 1000 scientific papers was reached. Even now ISO's data archive remains a valuable source of new results. For example, some of the latest papers describe the detection of water in 'protostars', which are stars in the process of being born, and studies of numerous nearby galaxies. "Of course we were confident ISO was going to do very well, but its actual productivity has been far beyond our expectations. The publication rate does not even seem to have peaked yet! We expect many more results," Salama says. Note for editors ISO's data archive contains scientific data from about 30 000 observations. Astronomers from all over the world have downloaded almost eight times the equivalent of the entire scientific archive. As much as 35% of all ISO observations have already been published at least once in prestigious scientific journals. ESA is now preparing to continue its infrared investigation of the Universe. The next generation of infrared space observatories is already in the pipeline. ISO is to be followed by the NASA SIRTF observatory to be launched later this year. Then, in 2007, ESA will follow up the pioneering work of ISO with the Herschel Space Observatory, which will become the largest imaging telescope ever put into space. ISO The Infrared Space Observatory (ISO) was launched in 1995 and operated from November that year to May 1998, when it ran out of the coolant needed to keep its detectors working. At the time it was the most sensitive infrared satellite ever launched and made particularly important studies of the dusty regions of the Universe, where visible light telescopes can see nothing. ESA will reopen its examination of the infrared Universe when Herschel is launched in 2007. Herschel Herschel will be the largest space telescope when, in 2007, it is launched on an Ariane-5 rocket, together with ESA’s cosmology mission, Planck. Herschel’s 3.5-metre diameter mirror will collect longwave infrared radiation from some of the coolest and most

  13. Water-vapor absorption line measurements in the 940-nm band by using a Raman-shifted dye laser

    NASA Technical Reports Server (NTRS)

    Chu, Zhiping; Wilkerson, Thomas D.; Singh, Upendra N.

    1993-01-01

    We report water-vapor absorption line measurements that are made by using the first Stokes radiation (930-982 nm) with HWHM 0.015/cm generated by a narrow-linewidth, tunable dye laser. Forty-five absorption line strengths are measured with an uncertainty of 6 percent and among them are fourteen strong lines that are compared with previous measurements for the assessment of spectral purity of the light source. Thirty air-broadened linewidths are measured with 8 percent uncertainty at ambient atmospheric pressure with an average of 0.101/cm. The lines are selected for the purpose of temperature-sensitive or temperature-insensitive lidar measurements. Results for these line strengths and linewidths are corrected for broadband radiation and finite laser linewidth broadening effects and compared with the high-resolution transmission molecular absorption.

  14. Symmetry-Breaking in Cationic Polymethine Dyes: Part 2. Shape of Electronic Absorption Bands Explained by the Thermal Fluctuations of the Solvent Reaction Field.

    PubMed

    Masunov, Artëm E; Anderson, Dane; Freidzon, Alexandra Ya; Bagaturyants, Alexander A

    2015-07-01

    The electronic absorption spectra of the symmetric cyanines exhibit dramatic dependence on the conjugated chain length: whereas short-chain homologues are characterized by the narrow and sharp absorption bands of high intensity, the long-chain homologues demonstrate very broad, structureless bands of low intensity. Spectra of the intermediate homologues combine both features. These broad bands are often explained using spontaneous symmetry-breaking and charge localization at one of the termini, and the combination of broad and sharp features was interpreted as coexistence of symmetric and asymmetric species in solution. These explanations were not supported by the first principle simulations until now. Here, we employ a combination of time-dependent density functional theory, a polarizable continuum model, and Franck-Condon (FC) approximation to predict the absorption line shapes for the series of 2-azaazulene and 1-methylpyridine-4-substituted polymethine dyes. To simulate inhomogeneous broadening by the solvent, the molecular structures are optimized in the presence of a finite electric field of various strengths. The calculated FC line shapes, averaged with the Boltzmann weights of different field strengths, reproduce the experimentally observed spectra closely. Although the polarizable continuum model accounts for the equilibrium solvent reaction field at absolute zero, the finite field accounts for the thermal fluctuations in the solvent, which break the symmetry of the solute molecule. This model of inhomogeneous broadening opens the possibility for computational studies of thermochromism. The choice of the global hybrid exchange-correlation functional SOGGA11-X, including 40% of the exact exchange, plays the critical role in the success of our model. PMID:26087319

  15. Investigation of SO3 absorption line for in situ gas detection inside combustion plants using a 4-μm-band laser source.

    PubMed

    Tokura, A; Tadanaga, O; Nishimiya, T; Muta, K; Kamiyama, N; Yonemura, M; Fujii, S; Tsumura, Y; Abe, M; Takenouchi, H; Kenmotsu, K; Sakai, Y

    2016-09-01

    We have investigated 4-μm-band SO3 absorption lines for in situSO3 detection using a mid-infrared laser source based on difference frequency generation in a quasi-phase-matched LiNbO3 waveguide. In the wavelength range of 4.09400-4.10600 μm, there were strong SO3 absorption lines. The maximum absorption coefficient at a concentration of 170 ppmv was estimated to be about 3.2×10-5  cm-1 at a gas temperature of 190°C. In coexistence with H2O, the reduction of the SO3 absorption peak height was observed, which was caused by sulfuric acid formation. We discuss a method of using an SO3 equilibrium curve to derive the total SO3 molecule concentration. PMID:27607263

  16. Calculating Effect of Point Defects on Optical Absorption Spectra of III-V Semiconductor Superlattices Based on (8x8) k-dot-p Band Structures

    NASA Astrophysics Data System (ADS)

    Huang, Danhong; Iurov, Andrii; Gumbs, Godfrey; Cardimona, David; Krishna, Sanjay

    For a superlattice which is composed of layered zinc-blende structure III-V semiconductor materials, its realistic anisotropic band structures around the Gamma-point are calculated by using the (8x8)k-dot-p method with the inclusion of the self-consistent Hartree potential and the spin-orbit coupling. By including the many-body screening effect, the obtained band structures are further employed to calculate the optical absorption coefficient which is associated with the interband electron transitions. As a result of a reduced quasiparticle lifetime due to scattering with point defects in the system, the self-consistent vertex correction to the optical response function is also calculated with the help of the second-order Born approximation.

  17. Quasi-random narrow-band model fits to near-infrared low-temperature laboratory methane spectra and derived exponential-sum absorption coefficients

    NASA Technical Reports Server (NTRS)

    Baines, Kevin H.; West, Robert A.; Giver, Lawrence P.; Moreno, Fernando

    1993-01-01

    Near-infrared 10/cm resolution spectra of methane obtained at various temperatures, pressures, and abundances are fit to a quasi-random narrow-band model. Exponential-sum absorption coefficients for three temperatures (112, 188, and 295 K), and 20 pressures from 0.0001 to 5.6 bars, applicable to the cold environments of the major planets, are then derived from the band model for the 230 wavelengths measured from 1.6 to 2.5 microns. RMS deviations between the laboratory and the exponential-sum synthetic transmissions are reported for the best fitting 50 wavelengths. Deviations relevant to broadband, 1-percent spectral resolution observations are also presented. The validity of exponential-sum coefficients derived from broadband (10/cm) transmission data is demonstrated via direct comparison with line-by-line calculations. The complete atlas of coefficients is available from the Planetary Data System-Planetary Atmospheres Discipline Node.

  18. Visible-light absorption and large band-gap bowing of GaN1-xSbx from first principles

    SciTech Connect

    Sheetz, R. Michael; Richter, Ernst; Andriotis, Antonis N.; Lisenkov, Sergey; Pendyala, Chandrashekhar; Sunkara, Mahendra K.; Menon, Madhu

    2011-08-01

    Applicability of the Ga(Sbx)N1-x alloys for practical realization of photoelectrochemical water splitting is investigated using first-principles density functional theory incorporating the local density approximation and generalized gradient approximation plus the Hubbard U parameter formalism. Our calculations reveal that a relatively small concentration of Sb impurities is sufficient to achieve a significant narrowing of the band gap, enabling absorption of visible light. Theoretical results predict that Ga(Sbx)N1-x alloys with 2-eV band gaps straddle the potential window at moderate to low pH values, thus indicating that dilute Ga(Sbx)N1-x alloys could be potential candidates for splitting water under visible light irradiation.

  19. Visible-light absorption and large band-gap bowing of GaN1-xSbx from first principles

    DOE PAGESBeta

    Sheetz, R. Michael; Richter, Ernst; Andriotis, Antonis N.; Lisenkov, Sergey; Pendyala, Chandrashekhar; Sunkara, Mahendra K.; Menon, Madhu

    2011-08-01

    Applicability of the Ga(Sbx)N1-x alloys for practical realization of photoelectrochemical water splitting is investigated using first-principles density functional theory incorporating the local density approximation and generalized gradient approximation plus the Hubbard U parameter formalism. Our calculations reveal that a relatively small concentration of Sb impurities is sufficient to achieve a significant narrowing of the band gap, enabling absorption of visible light. Theoretical results predict that Ga(Sbx)N1-x alloys with 2-eV band gaps straddle the potential window at moderate to low pH values, thus indicating that dilute Ga(Sbx)N1-x alloys could be potential candidates for splitting water under visible light irradiation.

  20. Evolution of dielectric function of Al-doped ZnO thin films with thermal annealing: effect of band gap expansion and free-electron absorption.

    PubMed

    Li, X D; Chen, T P; Liu, Y; Leong, K C

    2014-09-22

    Evolution of dielectric function of Al-doped ZnO (AZO) thin films with annealing temperature is observed. It is shown that the evolution is due to the changes in both the band gap and the free-electron absorption as a result of the change of free-electron concentration of the AZO thin films. The change of the electron concentration could be attributed to the activation of Al dopant and the creation/annihilation of the donor-like defects like oxygen vacancy in the thin films caused by annealing. PMID:25321779

  1. Wavelength-resolved optical extinction measurements of aerosols using broad-band cavity-enhanced absorption spectroscopy over the spectral range of 445-480 nm.

    PubMed

    Zhao, Weixiong; Dong, Meili; Chen, Weidong; Gu, Xuejun; Hu, Changjin; Gao, Xiaoming; Huang, Wei; Zhang, Weijun

    2013-02-19

    Despite the significant progress in the measurements of aerosol extinction and absorption using spectroscopy approaches such as cavity ring-down spectroscopy (CRDS) and photoacoustic spectroscopy (PAS), the widely used single-wavelength instruments may suffer from the interferences of gases absorption present in the real environment. A second instrument for simultaneous measurement of absorbing gases is required to characterize the effect of light extinction resulted from gases absorption. We present in this paper the development of a blue light-emitting diode (LED)-based incoherent broad-band cavity-enhanced spectroscopy (IBBCEAS) approach for broad-band measurements of wavelength-resolved aerosol extinction over the spectral range of 445-480 nm. This method also allows for simultaneous measurement of trace gases absorption present in the air sample using the same instrument. On the basis of the measured wavelength-dependent aerosol extinction cross section, the real part of the refractive index (RI) can be directly retrieved in a case where the RI does not vary strongly with the wavelength over the relevant spectral region. Laboratory-generated monodispersed aerosols, polystyrene latex spheres (PSL) and ammonium sulfate (AS), were employed for validation of the RI determination by IBBCEAS measurements. On the basis of a Mie scattering model, the real parts of the aerosol RI were retrieved from the measured wavelength-resolved extinction cross sections for both aerosol samples, which are in good agreement with the reported values. The developed IBBCEAS instrument was deployed for simultaneous measurements of aerosol extinction coefficient and NO(2) concentration in ambient air in a suburban site during two representative days. PMID:23320530

  2. Absorption spectral band width of charge transfer transition of E(T)(30) dye in homogeneous and heterogeneous media.

    PubMed

    Das, Parimal Kumar; Pramanik, Ramkrishna; Bagchi, Sanjib

    2003-06-01

    Solvation characteristics in homogeneous and heterogeneous media have been probed by monitoring the band width of ICT band of 2,6-di-phenyl-4(2,4,6-triphenyl-1-pyridino) phenolate, the indicator solute for E(T)(30) scale, in pure, mixed binary solvents and aqueous micellar solution. Non-ideal solvation behaviour is observed in all the binary solvent mixtures. Index of preferential solvation has been calculated as a function of solvent composition. Study in micellar media indicates that the dye is located at the micelle-water interface. The effects of variation of micelle concentration, temperature and electrolyte concentration have also been studies. PMID:12736053

  3. ESA Fire CCI product assessment

    NASA Astrophysics Data System (ADS)

    Heil, Angelika; Yue, Chao; Mouillot, Florent; Storm, Thomas; Chuvieco, Emilio; Kaiser, Johannes

    2016-04-01

    Vegetation fires are a major disturbance in the Earth System. Fires change the biophysical properties and dynamics of ecosystems and alter terrestrial carbon pools. By altering the atmosphere's composition, fire emissions exert a significant climate forcing. To realistically model past and future changes of the Earth System, fire disturbances must be taken into account. Related modelling efforts require consistent global burned area observations covering at least 10 to 20 years. Guided by the specific requirements of a wide range of end users, the ESA fire_cci project is currently computing a new global burned area dataset. It applies a newly developed spectral change detection algorithm upon the full ENVISAT-MERIS archive (2002 to 2012). The algorithm relies on MODIS active fire information as "seed". A first, formally validated version has been released for the period 2006 to 2008. It comprises a pixel burned area product (spatial resolution of 333 m) with date detection information and a biweekly grid product at 0.5 degree spatial resolution. We compare fire_cci burned area with other global burned area products (MCD64, GFED4(s), GEOLAND) and a set of active fires data (hotspots from MODIS, TRMM, AATSR and fire radiative power from GFAS). Output from the ongoing processing of the full MERIS timeseries will be incorporated into the study, as far as available. The analysis of patterns of agreement and disagreement between fire_cci and other products provides a better understanding of product characteristics and uncertainties. The intercomparison of the 2006-2008 fire_cci time series shows a close agreement with GFED4 data in terms of global burned area and the general spatial and temporal patterns. Pronounced differences, however, emerge for specific regions or fire events. Burned area mapped by fire_cci tends to be notably higher in regions where small agricultural fires predominate. The improved detection of small agricultural fires by fire_cci can be related to

  4. Rovibrational Intensities of the (00 03) ← (10 00) Dyad Absorption Bands of 12C 16O 2

    NASA Astrophysics Data System (ADS)

    Kshirsagar, Rohidas J.; Giver, Lawrence P.; Chackerian, Charles

    2000-02-01

    Absolute line intensities of 12C16O2 are experimentally measured for the first time for the (0003)I ← (1000)II band at 5687.17 cm-1 and the (0003)I ← (1000)I band at 5584.39 cm-1. The spectra were obtained using a Bomem DA8 Fourier transform spectrometer and a 25-m base-path White cell at NASA-Ames Research Center. The rotationless bandstrengths at a temperature of 296 K and the Herman-Wallis parameters are S0vib = 6.68(30) × 10-25 cm-1/(molecule/cm2); A1 = 1.4(9) × 10-4, and A2 = -1.1(5) × 10-5 for the (0003)I ← (1000)II band and S0vib = 6.07(22) × 10-25 cm-1/(molecule/cm2); A1 = 5.2(1.5) × 10-4 and A2 = -4.0(7) × 10-5 for the (0003)I ← (1000)I band.

  5. CarbonSat: ESA's Earth Explorer 8 Candidate Mission

    NASA Astrophysics Data System (ADS)

    Meijer, Y. J.; Ingmann, P.; Löscher, A.

    2012-04-01

    exploit a passive observing technique measuring scattered solar light with imaging spectrometers. It will perform measurements of CO2 and CH4 in combination with O2 to yield their dry column amounts. Spectral absorptions of CO2 in the 1.6 μm and 2 μm bands, O2 in the 760 nm and CH4 in the 1.65 μm spectral ranges measured with high spectral resolution of the order of between 0.03 and 0.3 nm and a high signal-to-noise ratio. The CarbonSat mission concept builds on the heritage and lessons learned from SCIAMACHY, GOSAT and OCO(-2) to make strategically important measurements of the amounts and distribution of CO2 and CH4 in the context of Climate Change.

  6. Antenna pointing mechanism for ESA ENVISAT polar platform

    NASA Technical Reports Server (NTRS)

    Serrano, J.; SanMillan, J.; Santiago, R.

    1996-01-01

    INTA is currently developing a two-degree-of-freedom antenna pointing mechanism (APM) as part of the ESA ENVISAT POLAR PLATFORM (PPF) program. This mechanism will drive a Ka-band antenna within the Data-Relay Satellite System (DRS) on board the Polar Platform satellite. The first mission using PPF is ENVISAT, which is expected to be flown in 1998. This paper describes the main requirements, design, and test results of this pointing system, as well as the main technical problems from customer requirements and how those have been faced to achieve a final design.

  7. Excited state absorption in chromium doped Li2B4O7 glass

    NASA Astrophysics Data System (ADS)

    Koepke, Cz; Wisniewski, K.; Grinberg, M.; Majchrowski, A.; Han, T. P. J.

    2001-03-01

    Excited state absorption (ESA) measurements of the Cr:Li2B4O7 glass (Cr:LBO-glass) along with preliminary interpretation are presented. The presence of chromium in its tri- (d3) and hexa- (d0) valence states is observed. Both Cr3+ and Cr6+ ions appear to contribute in the de-excitation processes and can be attributed in the ESA spectra under excitation wavelengths at 308 nm, 488 nm, 515 nm and 610 nm. The ESA spectra detected with UV excitation have been interpreted in terms of transitions in the framework of the Cr5+O- centre, which forms after charge-transfer-type absorption in the [CrO4]2- group. Assumption of the double-electron state of the 3d22p4 electronic configuration together with crystal-field-split states of the 3d12p5 configuration allowed us to reproduce the obtained ESA spectra. The ESA spectra of the Cr3+ ions have different characteristics and are related to transitions to the conduction band.

  8. ESA's Integral discovers hidden black holes

    NASA Astrophysics Data System (ADS)

    2003-10-01

    An artist's impression of the mechanisms in an interacting binar hi-res Size hi-res: 28 kb An artist's impression of the mechanisms in an interacting binary system An artist's impression of the mechanisms in an interacting binary system. The supermassive companion star (on the right-hand side) ejects a lot of gas in the form of 'stellar wind'. The compact black hole orbits the star and, due to its strong gravitational attraction, collects a lot of the gas. Some of it is funnelled and accelerated into a hot disc. This releases a large amount of energy in all spectral bands, from gamma rays through to visible and infrared. However, the remaining gas surrounding the black hole forms a thick cloud which blocks most of the radiation. Only the very energetic gamma rays can escape and be detected by Integral. XMM-Newton spacecraft hi-res Size hi-res: 254 kb Credits: ESA. Illustration by Ducros XMM-Newton spacecraft Detecting the Universe's hot spots. These are binary systems, probably including a black hole or a neutron star, embedded in a thick cocoon of cold gas. They have remained invisible so far to all other telescopes. Integral was launched one year ago to study the most energetic phenomena in the universe. Integral detected the first of these objects, called IGRJ16318-4848, on 29 January 2003. Although astronomers did not know its distance, they were sure it was in our Galaxy. Also, after some analysis, researchers concluded that the new object could be a binary system comprising a compact object, such as a neutron star or a black hole, and a very massive companion star. When gas from the companion star is accelerated and swallowed by the more compact object, energy is released at all wavelengths, from the gamma rays through to visible and infrared light. About 300 binary systems like those are known to exist in our galactic neighbourhood and IGRJ16318-4848 could simply have been one more. But something did not fit: why this particular object had not been

  9. A Multi-Band Analytical Algorithm for Deriving Absorption and Backscattering Coefficients from Remote-Sensing Reflectance of Optically Deep Waters

    NASA Technical Reports Server (NTRS)

    Lee, Zhong-Ping; Carder, Kendall L.

    2001-01-01

    A multi-band analytical (MBA) algorithm is developed to retrieve absorption and backscattering coefficients for optically deep waters, which can be applied to data from past and current satellite sensors, as well as data from hyperspectral sensors. This MBA algorithm applies a remote-sensing reflectance model derived from the Radiative Transfer Equation, and values of absorption and backscattering coefficients are analytically calculated from values of remote-sensing reflectance. There are only limited empirical relationships involved in the algorithm, which implies that this MBA algorithm could be applied to a wide dynamic range of waters. Applying the algorithm to a simulated non-"Case 1" data set, which has no relation to the development of the algorithm, the percentage error for the total absorption coefficient at 440 nm a (sub 440) is approximately 12% for a range of 0.012 - 2.1 per meter (approximately 6% for a (sub 440) less than approximately 0.3 per meter), while a traditional band-ratio approach returns a percentage error of approximately 30%. Applying it to a field data set ranging from 0.025 to 2.0 per meter, the result for a (sub 440) is very close to that using a full spectrum optimization technique (9.6% difference). Compared to the optimization approach, the MBA algorithm cuts the computation time dramatically with only a small sacrifice in accuracy, making it suitable for processing large data sets such as satellite images. Significant improvements over empirical algorithms have also been achieved in retrieving the optical properties of optically deep waters.

  10. Christmas on Mars: be there with ESA

    NASA Astrophysics Data System (ADS)

    2003-12-01

    The exciting event can be followed at ESA’s European Space Operations Centre (ESOC) in Darmstadt, Germany, on Thursday, 25 December, from 01:30 to 14:00, together with the mission managers, the operation teams, scientists and top ESA management, including ESA’s Director-General Jean-Jacques Dordain, ESA’s Director of Science David Southwood and ESA’s Director of Technical and Operational Support Gaele Winters. The highlights of the night will be also webcast over the internet http://mars.esa.int. As well as live streaming of key events, the Mars Express site will have daily news, features, images, videos and more. The ESA TV Service will provide live coverage of operations, from the Operations Control Centre at ESOC. All transmission and satellite details are published online at http://television.esa.int All live transmissions are also carried free-to-air on Astra 2 C at 19 degrees East, transponder 57, horizontal, (DVB-MPEG-2), frequency 10832 MHz, Symbol Rate 22000 MS/sec, FEC 5/6. The service name is ESA Media wishing to attend are asked to complete the attached reply form and fax it back to ESA Media Relations Service: +33 (0)1 53 69 76 90.

  11. ESA Science Archives and associated VO activities

    NASA Astrophysics Data System (ADS)

    Arviset, Christophe; Baines, Deborah; Barbarisi, Isa; Castellanos, Javier; Cheek, Neil; Costa, Hugo; Fajersztejn, Nicolas; Gonzalez, Juan; Fernandez, Monica; Laruelo, Andrea; Leon, Ignacio; Ortiz, Inaki; Osuna, Pedro; Salgado, Jesus; Tapiador, Daniel

    ESA's European Space Astronomy Centre (ESAC), near Madrid, Spain, hosts most of ESA space based missions' scientific archives, in planetary (Mars Express, Venus Express, Rosetta, Huygens, Giotto, Smart-1, all in ESA Planetary Science Archive), in astronomy (XMM-Newton, Herschel, ISO, Integral, Exosat, Planck) and in solar physics (Soho). All these science archives are operated by a dedicated Science Archives and Virtual Observatory Team (SAT) at ESAC, enabling common and efficient design, development, operations and maintenance of the archives software systems. This also ensures long term preservation and availability of such science archives, as a sustainable service to the science community. ESA space science data can be accessed through powerful and user friendly user interface, as well as from machine scriptable interface and through VO interfaces. Virtual Observatory activities are also fully part of ESA archiving strategy and ESA is a very ac-tive partner in VO initiatives in Europe through Euro-VO AIDA and EuroPlanet and worldwide through the IVOA (International Virtual Observatory Alliance) and the IPDA (International Planetary Data Alliance).

  12. Correlation between atmospheric O4 and H2O absorption in visible band and its implication to dust and haze events in Shanghai, China

    NASA Astrophysics Data System (ADS)

    Wang, Shanshan; Zhao, Heng; Yang, Suna; Wang, Zhuoru; Zhou, Bin; Chen, Limin

    2012-12-01

    Ground-based zenith-sky DOAS observation was carried out from October 1, 2009 to September 30, 2010 in Shanghai, China to measure the O4 and H2O absorption in visible band and to illustrate the dependence of their correlation slope on the aerosol pollution type. Good correlations between O4 and H2O DSCDs can be found through linear regression analysis whether it was sunny, cloudy, overcast, or rainy. The correlation slope varied seasonally in the order of summer < autumn, spring < winter. In particular, the correlation slope and fluctuation were small in the summer. It was found that slope values also relied on sky conditions generally in the sequence of dusty > sunny > cloudy > overcast > rainy. The implication of the variation of slope to the aerosol pollution type was discussed for typical heavy dust and haze episodes occurred in March 2010 and October 2009, respectively. As the correlation slope abruptly increased during the heavy dust due to low moisture content and enhanced O4 absorption caused by abundant suspended dry crustal particles, the slope dropped suddenly in the haze episode owing to the significant augment of H2O absorption. Thus, the much discrepant correlation patterns may be regarded as a characteristic signature for dust and haze events.

  13. ESA airborne campaigns in support of Earth Explorers

    NASA Astrophysics Data System (ADS)

    Casal, Tania; Davidson, Malcolm; Schuettemeyer, Dirk; Perrera, Andrea; Bianchi, Remo

    2013-04-01

    In the framework of its Earth Observation Programmes the European Space Agency (ESA) carries out ground based and airborne campaigns to support geophysical algorithm development, calibration/validation, simulation of future spaceborne earth observation missions, and applications development related to land, oceans and atmosphere. ESA has been conducting airborne and ground measurements campaigns since 1981 by deploying a broad range of active and passive instrumentation in both the optical and microwave regions of the electromagnetic spectrum such as lidars, limb/nadir sounding interferometers/spectrometers, high-resolution spectral imagers, advanced synthetic aperture radars, altimeters and radiometers. These campaigns take place inside and outside Europe in collaboration with national research organisations in the ESA member states as well as with international organisations harmonising European campaign activities. ESA campaigns address all phases of a spaceborne missions, from the very beginning of the design phase during which exploratory or proof-of-concept campaigns are carried out to the post-launch exploitation phase for calibration and validation. We present four recent campaigns illustrating the objectives and implementation of such campaigns. Wavemill Proof Of Concept, an exploratory campaign to demonstrate feasibility of a future Earth Explorer (EE) mission, took place in October 2011 in the Liverpool Bay area in the UK. The main objectives, successfully achieved, were to test Astrium UKs new airborne X-band SAR instrument capability to obtain high resolution ocean current and topology retrievals. Results showed that new airborne instrument is able to retrieve ocean currents to an accuracy of ± 10 cms-1. The IceSAR2012 campaign was set up to support of ESA's EE Candidate 7,BIOMASS. Its main objective was to document P-band radiometric signatures over ice-sheets, by upgrading ESA's airborne POLARIS P-band radar ice sounder with SAR capability. Campaign

  14. Band gap formation in La0.7Sr0.3MnO3 (LSMO) thin films measured by reflectivity/absorption and ultrafast spectroscopy

    NASA Astrophysics Data System (ADS)

    Cabrera, Guerau; Trappen, Robbyn; Chu, Ying-Hao; Holcomb, Mikel

    Thin film La0.7Sr0.3MnO3 (LSMO) is a prime candidate for highly spin-polarized magnetic-tunnel-junction memories. Due to its magnetic properties, it is also a good candidate for applications utilizing electrical control of magnetism when grown adjacent to a ferroelectric layer such as Pb(Zr/Ti)O3 (PZT). Recently, Wu and others have seen the emergence of a band gap (about 1eV) in LSMO thin films, when grown adjacent to PZT. Currently, it is understood that LSMO is a half-metal, with a pseudo-gap due to a low desity of states (DOS) near the Fermi level. The transition from pseudo-gap to band gap is not yet fully understood. It is therefore our aim to investigate the formation of this band gap through optical reflectivity/absorption and ultrafast carrier dynamics for a variety of thicknesses ranging from a few nanometers to thicker films (about 100 nm).

  15. Efficient tissue ablation using a laser tunable in the water absorption band at 3 microns with little collateral damage

    NASA Astrophysics Data System (ADS)

    Nierlich, Alexandra; Chuchumishev, Danail; Nagel, Elizabeth; Marinova, Kristiana; Philipov, Stanislav; Fiebig, Torsten; Buchvarov, Ivan; Richter, Claus-Peter

    2014-03-01

    Lasers can significantly advance medical diagnostics and treatment. At high power, they are typically used as cutting tools during surgery. For lasers that are used as knifes, radiation wavelengths in the far ultraviolet and in the near infrared spectral regions are favored because tissue has high contents of collagen and water. Collagen has an absorption peak around 190 nm, while water is in the near infrared around 3,000 nm. Changing the wavelength across the absorption peak will result in significant differences in laser tissue interactions. Tunable lasers in the infrared that could optimize the laser tissue interaction for ablation and/or coagulation are not available until now besides the Free Electron Laser (FEL). Here we demonstrate efficient tissue ablation using a table-top mid-IR laser tunable between 3,000 to 3,500 nm. A detailed study of the ablation has been conducted in different tissues. Little collateral thermal damage has been found at a distance above 10-20 microns from the ablated surface. Furthermore, little mechanical damage could be seen in conventional histology and by examination of birefringent activity of the samples using a pair of cross polarizing filters.

  16. Cryosphere campaigns in support of ESA's Earth Explorers Missions

    NASA Astrophysics Data System (ADS)

    Casal, Tânia; Davidson, Malcolm; Plank, Gernot; Floberghagen, Rune; Parrinello, Tommaso; Mecklenburg, Susanne; Drusch, Matthias; Fernandez, Diego

    2014-05-01

    In the framework of its Earth Observation Programmes the European Space Agency (ESA) carries out ground based and airborne campaigns to support geophysical algorithm development, calibration/validation, simulation of future spaceborne Earth observation missions, and applications development related to land, oceans, atmosphere and solid Earth. ESA has conducted over 110 airborne and ground measurements campaigns since 1981 and this presentation will describe three campaigns in Antarctica and the Arctic. They were undertaken during the calibration/validation phase of Earth Explorer (EE) missions, such as SMOS (Soil Moisture and Ocean Salinity), GOCE (Gravity field and steady-state Ocean Circulation Explorer) and CryoSat-2. In support of SMOS and GOCE, the DOMECair airborne campaign took place in Antarctica, in the Dome C region in the middle of January 2013. The two main objectives were a) to quantify and document the spatial variability in the DOME C area (SMOS) and b) to fill a gap in the high-quality gravity anomaly maps in Antarctica where airborne gravity measurements are sparse (GOCE). Results from the campaign for the SMOS component, showed that the DOME C area is not as spatially homogenous as previously assumed, therefore comparisons of different missions (e.g. SMOS and NASA's Aquarius) with different footprints must be done with care, highlighting once again the importance of field work to test given assumptions. One extremely surprising outcome of this campaign was the pattern similarity between the gravity measurements and brightness temperature fields. To date, there has never been an indication that L-Band brightness temperatures could be correlated to gravity, but preliminary analysis showed coincident high brightness temperature with high gravity values, suggesting that topography may influence microwave emissions. Also in support of SMOS, the SMOSice airborne campaign has been planned in the Arctic. It was motived by a previous ESA SMOSice study that

  17. The first UV absorption band of l-tryptophan is not due to two simultaneous orthogonal electronic transitions differing in the dipole moment.

    PubMed

    Catalán, Javier

    2016-06-01

    Based on UV/Vis spectroscopic evidence obtained in this work, the first band in the absorption spectrum of l-tryptophan is largely due to a single electronic transition from the ground state to the (1)Lb excited state. However, emission spectra of this compound recorded at a variable temperature in ethanol, n-butanol and diethyl ether are structureless and considerably red-shifted at room temperature; also, lowering the temperature causes the emission to become structured and to undergo such a strong blue shift that it appears to be due to the (1)Lb state of the compound. Based on these findings, the formation (from the excited (1)Lb state) of the excited state responsible for the structureless, markedly red-shifted emission in l-tryptophan is strongly dependent not only on the viscosity of the medium, but also on its dipolarity. PMID:27197597

  18. Confinement effect of laser ablation plume in liquids probed by self-absorption of C{sub 2} Swan band emission

    SciTech Connect

    Sakka, Tetsuo; Saito, Kotaro; Ogata, Yukio H.

    2005-01-01

    The (0,0) Swan band of the C{sub 2} molecules in a laser ablation plume produced on the surface of graphite target submerged in water was used as a probe to estimate the density of C{sub 2} molecules in the plume. Observed emission spectra were reproduced excellently by introducing a self-absorption parameter to the theoretical spectral profile expected by a rotational population distribution at a certain temperature. The optical density of the ablation plume as a function of time was determined as a best-fit parameter by the quantitative fitting of the whole spectral profile. The results show high optical densities for the laser ablation plume in water compared with that in air. It is related to the plume confinement or the expansion, which are the important phenomena influencing the characteristics of laser ablation plumes in liquids.

  19. ESA personal communications and digital audio broadcasting systems based on non-geostationary satellites

    NASA Technical Reports Server (NTRS)

    Logalbo, P.; Benedicto, J.; Viola, R.

    1993-01-01

    Personal Communications and Digital Audio Broadcasting are two new services that the European Space Agency (ESA) is investigating for future European and Global Mobile Satellite systems. ESA is active in promoting these services in their various mission options including non-geostationary and geostationary satellite systems. A Medium Altitude Global Satellite System (MAGSS) for global personal communications at L and S-band, and a Multiregional Highly inclined Elliptical Orbit (M-HEO) system for multiregional digital audio broadcasting at L-band are described. Both systems are being investigated by ESA in the context of future programs, such as Archimedes, which are intended to demonstrate the new services and to develop the technology for future non-geostationary mobile communication and broadcasting satellites.

  20. Microwave absorption in X and Ku band frequency of cotton fabric coated with Ni-Zn ferrite and carbon formulation in polyurethane matrix

    NASA Astrophysics Data System (ADS)

    Gupta, K. K.; Abbas, S. M.; Goswami, T. H.; Abhyankar, A. C.

    2014-08-01

    The present study highlights various microwave properties, i.e. reflection, transmission, absorption and reflection loss, of the coated cotton fabric [formulation: Ni-Zn ferrite (Ni 0.5Zn0.5Fe2O4) and carbon black (acetylene black) at concentrations of 30, 40, 50, 60 and70 g of ferrite and 5 g carbon in each 100 ml polyurethane] evaluated at 8-18 GHz frequency. The uniform density of filling materials in coated fabrics (dotted marks in SEM micrograph) indicates homogeneous dispersion of conducting fillers in polyurethane and the density of filling material cluster increases with increase in ferrite concentration. SEM images also show uniform coating of conducting fillers/resin system over individual fibers and interweave spaces. The important parameters governing the microwave properties of coated fabrics i.e. permittivity and permeability, S-parameters, reflection loss, etc. were studied in a HVS free space microwave measurement system. The lossy character of coated fabric is found to increase with increase of ferrite content; the ferrite content decreases the impedance and increases the permittivity and permeability values. The 1.6-1.8 mm thick coated fabric sample (40 wt% ferrite, 3 wt% carbon and 57 wt% PU) has shown about 40% absorption, 20% transmission and 40% reflectance in X (8.2-12.4 GHz) and Ku (12-18 GHz) frequency bands. The reflection loss at 13.5 GHz has shown the highest peak value (22.5 dB) due to coated sample optical thickness equal to λ/4 and more than 7.5 dB in entire Ku band. Owing to its thin and flexible nature, the coated fabric can be used as apparel in protecting human being from hazardous microwaves and also as radar camouflage covering screen in defense.

  1. The New ESA Planetary Science Archive

    NASA Astrophysics Data System (ADS)

    Barbarisi, I.; Rios, C.; Macfarlane, A. J.; Docasal, R.; Gonzalez, J.; Arviset, C.; De Marchi, G.; Martinez, S.; Grotheer, E.; Lim, T.; Besse, S.; Heather, D.; Fraga, D.; Barthelemy, M.

    2015-12-01

    The ESA's Planetary Science Archive (PSA) is the central repository for all scientific and engineering data returned by ESA's planetary missions, making them accessible to the world-wide scientific community.With the advent of new ESA planetary missions, currently in development Bepi Colombo (Mercury) and ExoMars16 (Mars), and later on ExoMars18 (Mars Rover) and JUICE (Jupiter and moons), the PSA faces the need of supporting new functionalities and requirements.Within this scenario there is a need for a new concept of the PSA, supporting both the evolution of the PDS standard (PDS4), and the growing need for better interfaces and advanced applications toward a better science exploitation. We introduce the new PSA layout, conceived for better data discovery and retrieval, with special emphasis on GIS technology, interoperability and visualization capabilities.

  2. Modeling ESA's TT/C systems

    NASA Technical Reports Server (NTRS)

    Vassallo, Enrico

    1994-01-01

    After a brief introduction on the need for simulation packages for the analysis and design of satellite communications systems, the software tool developed for the European Space Agency (ESA), its main objectives and the design choices made during the development are presented. A very concise description of the available communications and measurement block follows. The ESA standard Telemetry, Tracking and Command (TT&C) system simulator is then introduced along with a description of the ESA standard modulation and coding schemes. As an example, the simulation of the ranging system which is a non-standard communications block, is described in details. Several examples of TT&C simulations outputs are given and compared with measurement results or theoretical approximations, when available. Finally, future developments like the support of advanced modulation schemes and the dynamic satellite link simulation are presented.

  3. Ulysses - An ESA/NASA cooperative programme

    NASA Technical Reports Server (NTRS)

    Meeks, W.; Eaton, D.

    1990-01-01

    Cooperation between ESA and NASA is discussed, noting that the Memorandum of Understanding lays the framework for this relationship, defining the responsibilities of ESA and NASA and providing for appointment of leadership and managers for the project. Members of NASA's Jet Propulsion Laboratory and ESA's ESTEC staff have been appointed to leadership positions within the project and ultimate control of the project rests with the Joint Working Group consisting of two project managers and two project scientists, equally representing both organizations. Coordination of time scales and overall mission design is discussed, including launch cooperation, public relations, and funding of scientific investigations such as Ulysses. Practical difficulties of managing an international project are discussed such as differing documentation requirements and communication techniques, and assurance of equality on projects.

  4. The Gravitational Universe - ESA's L3 mission

    NASA Astrophysics Data System (ADS)

    Mueller, Guido; Ando, Masaki; Binetruy, Pierre; Bouyer, Philippe; Cacciapuoti, Luigi; Cruise, Mike; Favata, Fabio; Gehler, Martin; Genzel, Reinhard; Jennrich, Oliver; Kasevich, Mark; Klipstein, Bill; Perryman, Michael; Safa, Frederic; Schutz, Bernard; Stebbins, Robin; Vitale, Stefano

    2015-04-01

    Following the advice of ESA's Senior Survey Committee (SSC) the Science Programme Committee (SPC) decided in November 2013 to select the science theme ``The Gravitational Universe'' for their L3 mission. The Director of Science and Robotic Exploration (D/SRE) has established a Gravitational Observatory Advisory Team (GOAT) to advise on the scientific and technological approaches for a gravitational wave observatory with a planned launch date in 2034. Our team is comprised of scientists from Europe and the US as well as scientists and engineers from ESA and observers from NASA and JAXA. We meet about every ten weeks, evaluate the technical readiness of all necessary technologies, study the science impact of different mission designs, and will advise ESA on the required future technology development. We will report on our progress and plans forward to a future space-based gravitational-wave observatory. For JAXA.

  5. ESA's Earth Observation in Support of Geoscience

    NASA Astrophysics Data System (ADS)

    Liebig, Volker

    2016-04-01

    The intervention will present ESA's Earth Observation Programme and its contribution to Geoscience. ESA's Earth observation missions are mainly grouped into three categories: The Sentinel satellites in the context of the European Copernicus Programme, the scientific Earth Explorers and the meteorological missions. Developments, applications and scientific results for the different mission types will be addressed, along with overall trends and strategies. A special focus will be put on the Earth Explorers, who form the science and research element of ESA's Living Planet Programme and focus on the atmosphere, biosphere, hydrosphere, cryosphere and Earth's interior. In addition the operational Sentinel satellites have a huge potential for Geoscience. Earth Explorers' emphasis is also on learning more about the interactions between these components and the impact that human activity is having on natural Earth processes. The process of Earth Explorer mission selection has given the Earth science community an efficient tool for advancing the understanding of Earth as a system.

  6. Iron-absorption band analysis for the discrimination of iron-rich zones. [infrared spectral reflectance of Nevada iron deposits

    NASA Technical Reports Server (NTRS)

    Rowan, L. C. (Principal Investigator)

    1974-01-01

    The author has identified the following significant results. Most major rock units and unaltered and altered areas in the study area can be discriminated on the basis of visible and near-infrared spectral reflectivity differences recorded from satellite altitude. These subtle spectral differences are detectable by digital ratioing of the MSS bands and subsequent stretching to increase the contrast to enhance spectral differences. Hydrothermally altered areas appear as anomalous color patches within the volcanic-rock areas. A map has been prepared which can be regarded as an excellent reconnaissance exploration map, for use in targeting areas for more detailed geological, geochemical, and geophysical studies. Mafic and felsic rock types are easily discriminated on the color stretched-ratio composite. The ratioing process minimizes albedo effects, leaving only the recorded characteristic spectral response. The spectra of unaltered rocks appear different from those of altered rocks, which are typically dominated by limonite and clay minerals. It seems clear that differences in spectral shape can provide a basis for discrimination of geologic material, although the relations between visible and near-infrared spectral reflectivity and mineralogical composition are not yet entirely understood.

  7. Time-Dependent Density Functional Theory Study of Low-Lying Absorption and Fluorescence Band Shapes for Phenylene-Containing Oligoacenes.

    PubMed

    Jun, Ye

    2015-12-24

    Low-lying band shapes of absorption and fluorescence spectra for a member of a newly synthesized family of phenylene-containing oligoacenes (POA 6) reported in J. Am. Chem. Soc. 2012 , 134 , 15351 are studied theoretically with two different approaches with TIPS-anthracene as a comparison. Underlying photophysics and exciton-phonon interactions in both molecules are investigated in details with the aid of the time-dependent density functional theory and multimode Brownian oscillator model. The first two low-lying excited-states of POA 6 were found to exhibit excitation characteristics spanning entire conjugated backbone despite the presence of antiaromatic phenylene section. Absorption and fluorescence spectra calculated from both time-dependent density functional theory and multimode Brownian oscillator model are shown to reach good agreement with experimental ones. The coupling between phonon modes and optical transitions is generally weak as suggested by the multimode Brownian oscillator model. Broader peaks of POA 6 spectra are found to relate to stronger coupling between low frequency phonon modes such as backbone twisting (with frequency <300 cm(-1)) and optical transitions. Furthermore, POA 6 exhibits weaker exciton-phonon coupling for the phonon modes above 1000 cm(-1) compared to TIPS-anthracene owing to extended conjugated backbone. A significant coupling between an in-plane breathing mode localized around the antiaromatic phenylene segment with frequency at 1687 cm(-1) and optical transitions for the first two excited-states of POA 6 is also observed. PMID:26611665

  8. Assignment and modeling of the absorption spectrum of 13CH4 at 80 K in the region of the 2ν3 band (5853-6201 cm-1)

    NASA Astrophysics Data System (ADS)

    Starikova, E.; Nikitin, A. V.; Rey, M.; Tashkun, S. A.; Mondelain, D.; Kassi, S.; Campargue, A.; Tyuterev, Vl. G.

    2016-07-01

    The absorption spectrum of the 13CH4 methane isotopologue has been recently recorded by Differential Absorption Spectroscopy (DAS) at 80 K in the 5853-6201 cm-1 spectral range. An empirical list of 3717 lines was constructed for this spectral range corresponding to the upper part of the Tetradecad dominated by the 2ν3 band near 5987 cm-1. In this work, we present rovibrational analyses of these spectra obtained via two theoretical approaches. Assignments of strong and medium lines were achieved with variational calculations using ab initio potential energy (PES) and dipole moment surfaces. For further analysis a non-empirical effective Hamiltonian (EH) of the methane polyads constructed by high-order Contact Transformations (CT) from an ab initio PES was employed. Initially predicted values of EH parameters were empirically optimized using 2898 assigned line positions fitted with an rms deviation of 5×10-3 cm-1. More than 1860 measured line intensities were modeled using the effective dipole transition moments approach with the rms deviation of about 10%. These new data were used for the simultaneous fit of the 13CH4 Hamiltonian parameters of the {Ground state/Dyad/Pentad/Octad/Tetradecad} system and the dipole moment parameters of the {Ground state-Tetradecad} system. Overall, 10 vibrational states and 28 vibration sublevels of the 13CH4 Tetradecad are determined. The comparison of their energy values with corresponding theoretical calculations is discussed.

  9. 29 CFR 42.9 - Farm Labor Specialist (ESA).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 1 2010-07-01 2010-07-01 true Farm Labor Specialist (ESA). 42.9 Section 42.9 Labor Office of the Secretary of Labor COORDINATED ENFORCEMENT § 42.9 Farm Labor Specialist (ESA). (a) The Assistant Secretary for ESA shall designate ESA Compliance Officers as Farm Labor Specialists...

  10. 29 CFR 42.9 - Farm Labor Specialist (ESA).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 1 2014-07-01 2013-07-01 true Farm Labor Specialist (ESA). 42.9 Section 42.9 Labor Office of the Secretary of Labor COORDINATED ENFORCEMENT § 42.9 Farm Labor Specialist (ESA). (a) The Assistant Secretary for ESA shall designate ESA Compliance Officers as Farm Labor Specialists...

  11. 29 CFR 42.9 - Farm Labor Specialist (ESA).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 1 2012-07-01 2012-07-01 false Farm Labor Specialist (ESA). 42.9 Section 42.9 Labor Office of the Secretary of Labor COORDINATED ENFORCEMENT § 42.9 Farm Labor Specialist (ESA). (a) The Assistant Secretary for ESA shall designate ESA Compliance Officers as Farm Labor Specialists...

  12. 29 CFR 42.9 - Farm Labor Specialist (ESA).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 1 2011-07-01 2011-07-01 false Farm Labor Specialist (ESA). 42.9 Section 42.9 Labor Office of the Secretary of Labor COORDINATED ENFORCEMENT § 42.9 Farm Labor Specialist (ESA). (a) The Assistant Secretary for ESA shall designate ESA Compliance Officers as Farm Labor Specialists...

  13. 29 CFR 42.9 - Farm Labor Specialist (ESA).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 1 2013-07-01 2013-07-01 false Farm Labor Specialist (ESA). 42.9 Section 42.9 Labor Office of the Secretary of Labor COORDINATED ENFORCEMENT § 42.9 Farm Labor Specialist (ESA). (a) The Assistant Secretary for ESA shall designate ESA Compliance Officers as Farm Labor Specialists...

  14. Time-resolved absorption changes of the pheophytin Q{sub x} band in isolated photosystem II reaction centers at 7K : energy transfer and charge separation.

    SciTech Connect

    Greenfield, S. R.; Seibert, M.; Wasielewski, M. R.; Chemistry; LANL; NREL; Northwestern Univ.

    1999-09-30

    The pheophytin {alpha} Q{sub x} spectral region of the isolated photosystem II reaction center was investigated at 7 K using femtosecond transient absorption spectroscopy. At this temperature, uphill energy transfer, which greatly complicates the interpretation of the kinetics at or near room temperature, should be essentially shut off. Low-energy ({approx}100 nJ) pulses at 661 and 683 nm were used to excite the short-wavelength and long-wavelength sides of the composite Q{sub y} band, providing preferential excitation of the accessory pigment pool and P680, respectively. The data analysis uses a background subtraction technique developed earlier (Greenfield et al. J. Phys. Chem. B 1997, 101, 2251-2255) to remove the kinetic components of the data that are due to the large time-dependent changes in the background that are present in this spectral region. The instantaneous amplitude of the bleach of the pheophytin {alpha} Q{sub x} band with 683 nm excitation is roughly two-thirds of its final amplitude, providing strong evidence of a multimer description of the reaction center core. The subsequent growth of the bleach shows biphasic kinetics, similar to our earlier results at 278 K. The rate constant of the faster component is (5 ps){sup -1} for 683 nm excitation (a factor of almost two faster than at 278 K), and represents the intrinsic rate constant for charge separation. The bleach growth with 661 nm excitation is also biphasic; however, the faster component appears to be a composite of a (5 ps){sup -1} component corresponding to charge separation following subpicosecond energy transfer to the long-wavelength pigments and a roughly (22 ps){sup -1} component corresponding to charge separation limited by slow energy transfer. The combined quantum yield for these two energy transfer processes is near unity. For both excitation wavelengths, there is also a roughly (100 ps){sup -1} component to the bleach growth. Exposure to high excitation energies ({>=}1 {mu}J) at

  15. Time-resolved absorption changes of the pheophytin Q{sub x} band in isolated photosystem II reaction centers at 7 K: Energy transfer and charge separation

    SciTech Connect

    Greenfield, S.R.; Seibert, M.; Wasielewski, M.R.

    1999-09-30

    The pheophytin a Q{sub x} spectral region of the isolated photosystem II reaction center was investigated at 7 K using femtosecond transient absorption spectroscopy. At this temperature, uphill energy transfer, which greatly complicates the interpretation of the kinetics at or near room temperature, should be essentially shut off. Low-energy ({approximately}100 nJ) pulses at 661 and 683 nm were used to excite the short-wavelength and long-wavelength sides of the composite Q{sub y} band, providing preferential excitation of the accessory pigment pool and P680, respectively. The data analysis uses a background subtraction technique developed earlier (Greenfield et al. J. Phys. Chem. B 1997, 101, 2251--2255) to remove the kinetic components of the data that are due to the large time-dependent changes in the background that are present in this spectral region. The instantaneous amplitude of the bleach of the pheophytin a Q{sub x} band with 683 nm excitation is roughly two-thirds of its final amplitude, providing strong evidence of a multimer description of the reaction center core. The subsequent growth of the bleach shows biphasic kinetics, similar to the earlier results at 278 K. The rate constant of the faster component is (5 ps){sup {minus}1} for 683 nm excitation (a factor of almost two faster than at 278 K), and represents the intrinsic rate constant for charge separation. The bleach growth with 661 nm excitation is also biphasic; however, the faster component appears to be a composite of a (5 ps){sup {minus}1} component corresponding to charge separation following subpicosecond energy transfer to the long-wavelength pigments and a roughly (22 ps){sup {minus}1} component corresponding to charge separation limited by slow energy transfer. The combined quantum yield for these two energy transfer processes is near unity. For both excitation wavelengths, there is also a roughly (100 ps){sup {minus}1} component to the bleach growth. Exposure to high excitation

  16. From ESAS to Ares: A Chronology

    NASA Technical Reports Server (NTRS)

    Cook, Steven A.

    2007-01-01

    This viewgraph presentation reviews the decision making that led to the choice of the Ares launch vehicle. There are charts that show comparisons of the features of the ESAS launch vehicles. There is discussion of the rationale of the choice of using a Evolved Expendable Launch Vehicle (EELV) as the launch vehicle for the future Crew Exploration Vehicle.

  17. Modelling of Collision Induced Absorption Spectra Of H2-H2 Pairs for the Planetary Atmospheres Structure: The Second Overtone Band

    NASA Technical Reports Server (NTRS)

    Borysow, Aleksandra; Borysow, Jacek I.

    1998-01-01

    The main objective of the proposal was to model the collision induced, second overtone band of gaseous hydrogen at low temperatures. The aim of this work is to assist planetary scientists in their investigation of planetary atmospheres, mainly those of Uranus and Neptune. The recently completed extended database of collision induced dipole moments of hydrogen pairs allowed us, for the first time, to obtain dipole moment matrix elements responsible for the roto-vibrational collision induced absorption spectra of H2-H2 in the second overtone band. Despite our numerous attempts to publish those data, the enormous volume of the database did not allow us to do this. Instead, we deposited the data on a www site. The final part of this work has been partially supported by NASA, Division for Planetary Atmospheres. In order to use our new data for modelling purpose, we first needed to test how well we can reproduce the existing experimental data from theory, when using our new input data. Two papers resulted from this work. The obtained agreement between theoretical results and the measurements appeared to be within 10-30%. The obviously poorer agreement than observed for the first H2 overtone, the fundamental, and the rototranslational bands can be attributed to the fact that dipole moments responsible for the second overtone are much weaker, therefore susceptible to larger numerical uncertainties. At the same time, the intensity of the second overtone band is much weaker and therefore it is much harder to be measured accurately in the laboratory. We need to point out that until now, no dependable model of the 2nd overtone band was available for modelling of the planetary atmospheres. The only one, often referred to in previous works on Uranian and Neptune's atmospheres, uses only one lineshape, with one (or two) parameter(s) deduced at the effective temperature of Uranus (by fitting the planetary observation). After that, the parameter(s) was(were) made temperature

  18. A search for formic acid in the upper troposphere - A tentative identification of the 1105-per cm nu-6 band Q branch in high-resolution balloon-borne solar absorption spectra

    NASA Technical Reports Server (NTRS)

    Goldman, A.; Murcray, F. H.; Murcray, D. G.; Rinsland, C. P.

    1984-01-01

    Infrared solar absorption spectra recorded at 0.02-per cm resolution during a balloon flight from Alamogordo, NM (33 deg N), on March 23, 1981, have been analyzed for the possible presence of absorption by formic acid (HCOOH). An absorption feature at 1105 per cm has been tentatively identified in upper tropospheric spectra as due to the nu-6 band Q branch. A preliminary analysis indicates a concentration of about 0.6 ppbv and 0.4 ppbv near 8 and 10 km, respectively.

  19. A Search for Formic Acid in the Upper Troposphere: A Tentative Identification of the 1105-cm(exp -1) nu(sub 6) Band Q Branch in High-Resolution Balloon-Borne Solar Absorption Spectra

    NASA Technical Reports Server (NTRS)

    Goldman, A.; Murcray, F. H.; Murcray, D. G.; Rinsland, C. P.

    1984-01-01

    Infrared solar absorption spectra recorded at 0.02/cm resolution during a balloon flight from Alamogordo, N.M. (33 deg N), on March 23, 1981, have been analyzed for the possible presence of absorption by formic acid (HCOOH). An absorption feature at 1105/ cm has been tentatively identified in upper tropospheric spectra as due to the nu(sub 6) band Q branch. A preliminary analysis indicates a concentration of approx. = 0.6 ppbv and approx. = 0.4 ppbv near 8 and 10 km, respectively.

  20. ESA's planning and coordination of the OLYMPUS propagation experiment

    NASA Technical Reports Server (NTRS)

    Arbesser-Rastburg, B.

    1992-01-01

    An overview of the organization of the OLYMPUS propagation experimenters group (OPEX) is given. Preparations, participation, and experiments are described. Some examples for first statistical results are also reported. OLYMPUS, a 3-axis stabilized communications satellite was launched in 1989 for providing experimental telecommunications payloads and a propagation beacon payload at 12, 20, and 30 GHz to the European Space Agency. From previous experience (OTS), the Agency undertook to carry out extensive preparations with an eye on obtaining the statistical results needed within the limited available lifetime of the spacecraft. The OLYMPUS propagation experiment was conceived as part of ESA's space telecommunications applications program (ESA/IPC/(79)83) with the emphasis on exploring the possibilities and limitations of Ka-band satellite communications. The objectives of the OLYMPUS propagation campaign were: (1) characterization of the slant-path propagation conditions at 20/30 GHz in the various climatic regions of Europe; (2) improvement of the understanding of the link between atmospheric observable (rain rate, cloud thickness, etc.) to propagation impairments such as attenuation, depolarization, scintillation, etc.; and (3) arrive at improved propagation prediction methods.

  1. Cloud top height retrieval using the imaging polarimeter (3MI) top-of-atmosphere reflectance measurements in the oxygen absorption band

    NASA Astrophysics Data System (ADS)

    Kokhanovsky, Alexander; Munro, Rose

    2016-04-01

    The determination of cloud top height from a satellite has a number of applications both for climate studies and aviation safety. A great variety of methods are applied using both active and passive observation systems in the optical and microwave spectral regions. One of the most popular methods with good spatial coverage is based on the measurement of outgoing radiation in the spectral range where oxygen strongly absorbs incoming solar light. Clouds shield tropospheric oxygen reducing the depth of the corresponding absorption line as detected by a satellite instrument. Radiative transfer models are used to connect the solar light reflectance, e.g., in the oxygen A-band located around 761nm, and the cloud top height. The inverse problem is then solved e.g. using look-up tables, to determine the cloud top height. In this paper we propose a new fast and robust oxygen A-band method for the retrieval of cloud altitude using the Multi-viewing Multi-channel Multi-polarization Imaging instrument (3MI) on board the EUMETSAT Polar System Second Generation (EPS-SG). The 3MI measures the intensity at the wavelengths of 410, 443, 490, 555, 670, 763, 765, 865, 910, 1370, 1650, and 2130nm, and (for selected channels) the second and third Stokes vector components which allows the degree of linear polarization and the polarization orientation angle of reflected solar light to be derived at up to 14 observation angles. The instrument response function (to a first approximation) can be modelled by a Gaussian distribution with the full width at half maximum (FWHM) equal to 20nm for all channels except 765nm, 865nm, 1370nm, 1650nm, and 2130nm, where it is equal to 40nm. The FWHM at 763nm (the oxygen A-band location) is equal to 10nm. The following 3MI channels are used in the retrieval procedure: 670, 763, and 865nm. The channels at 670 and 865 nm are not affected by the oxygen absorption. The channel at 763nm is affected by the oxygen concentration vertical profile. The higher

  2. Modeled and Empirical Approaches for Retrieving Columnar Water Vapor from Solar Transmittance Measurements in the 0.72, 0.82, and 0.94 Micrometer Absorption Bands

    NASA Technical Reports Server (NTRS)

    Ingold, T.; Schmid, B.; Maetzler, C.; Demoulin, P.; Kaempfer, N.

    2000-01-01

    A Sun photometer (18 channels between 300 and 1024 nm) has been used for measuring the columnar content of atmospheric water vapor (CWV) by solar transmittance measurements in absorption bands with channels centered at 719, 817, and 946 nm. The observable is the band-weighted transmittance function defined by the spectral absorption of water vapor and the spectral features of solar irradiance and system response. The transmittance function is approximated by a three-parameter model. Its parameters are determined from MODTRAN and LBLRTM simulations or empirical approaches using CWV data of a dual-channel microwave radiometer (MWR) or a Fourier transform spectrometer (FTS). Data acquired over a 2-year period during 1996-1998 at two different sites in Switzerland, Bern (560 m above sea level (asl)) and Jungfraujoch (3580 m asl) were compared to MWR, radiosonde (RS), and FTS retrievals. At the low-altitude station with an average CWV amount of 15 mm the LBLRTM approach (based on recently corrected line intensities) leads to negligible biases at 719 and 946 nm if compared to an average of MWR, RS, and GPS retrievals. However, at 817 nm an overestimate of 2.7 to 4.3 mm (18-29%) remains. At the high-altitude station with an average CWV amount of 1.4 mm the LBLRTM approaches overestimate the CWV by 1.0, 1.4. and 0.1 mm (58, 76, and 3%) at 719, 817, and 946 nm, compared to the ITS instrument. At the low-altitude station, CWV estimates, based on empirical approaches, agree with the MWR within 0.4 mm (2.5% of the mean); at the high-altitude site with a factor of 10 less water vapor the agreement of the sun photometers (SPM) with the ITS is 0.0 to 0.2 mm (1 to 9% of the mean CWV there). Sensitivity analyses show that for the conditions met at the two stations with CWV ranging from 0.2 to 30 mm, the retrieval errors are smallest if the 946 nm channel is used.

  3. Application of surface pressure measurements of O2-band differential absorption radar system in three-dimensional data assimilation on hurricane: Part II - A quasi-observational study

    NASA Astrophysics Data System (ADS)

    Min, Qilong; Gong, Wei; Lin, Bing; Hu, Yongxiang

    2015-01-01

    This is the second part on assessing the impacts of assimilating various distributions of sea-level pressure (SLP) on hurricane simulations, using the Weather and Research Forecast (WRF) three dimensional variational data assimilation system (3DVAR). One key purpose of this series of study is to explore the potential of using remotely sensed sea surface barometric data from O2-band differential absorption radar system currently under development for server weather including hurricane forecasts. In this part II we further validate the conclusions of observational system simulation experiments (OSSEs) in the part I using observed SLP for three hurricanes that passed over the Florida peninsula. Three SLP patterns are tested again, including all available data near the Florida peninsula, and a band of observations either through the center or tangent to the hurricane position. Before the assimilation, a vortex SLP reconstruction technique is employed for the use of observed SLP as discussed in the part I. In agreement with the results from OSSEs, the performance of assimilating SLP is enhanced for the two hurricanes with stronger initial minimum SLP, leading to a significant improvement in the track and position relative to the control where no data are assimilated. On the other hand, however, the improvement in the hurricane intensity is generally limited to the first 24-48 h of integration, while a high resolution nested domain simulation, along with assimilation of SLP in the coarse domain, shows more profound improvement in the intensity. A diagnostic analysis of the potential vorticity suggests that the improved track forecasts are attributed to the combined effects of adjusting the steering wind fields in a consistent manner with having a deeper vortex, and the associated changes in the convective activity.

  4. Evolution of ESA's SSA Conjunction Prediction Service

    NASA Astrophysics Data System (ADS)

    Escobar, D.; Sancho, A. Tirado, J.; Agueda, A.; Martin, L.; Luque, F.; Fletcher, E.; Navarro, V.

    2013-08-01

    This paper presents the recent evolution of ESA's SSA Conjunction Prediction Service (CPS) as a result of an on-going activity in the Space Surveillance and Tracking (SST) Segment of ESA's Space Situational Awareness (SSA) Programme. The CPS is one of a number of precursor services being developed as part of the SST segment. It has been implemented as a service to provide external users with web-based access to conjunction information and designed with a service-oriented architecture. The paper encompasses the following topics: service functionality enhancements, integration with a live objects catalogue, all vs. all analyses supporting an operational concept based on low and high fidelity screenings, and finally conjunction detection and probability algorithms.

  5. The ESA Hubble 15th Anniversary Campaign

    NASA Astrophysics Data System (ADS)

    Christensen, L. L.; Kornmesser, M.

    2005-12-01

    The 15th anniversary of the launch of the NASA/ESA Hubble Space Telescope occurred on 24th April 2005. As Hubble is one of the most successful scientific projects in the world, ESA decided to celebrate this anniversary, among other things, with the production of a Hubble 15th Anniversary movie and a book, both called "Hubble, 15 years of discovery". The movie covers all aspects of the Hubble Space Telescope project - a journey through the history, the problems and the scientific successes of Hubble. With more than 700,000 multi-lingual DVDs distributed to the public, media, educators, decision-makers and scientists, the Hubble 15th anniversary campaign has been one of the largest such projects in Europe.

  6. ESA'S Biomass Mission System And Payload Overview

    NASA Astrophysics Data System (ADS)

    Arcioni, M.; Bensi, P.; Fois, F.; Gabriele, A.; Heliere, F.; Lin, C. C.; Massotti, L.; Scipal, K.

    2013-12-01

    Earth Explorers are the backbone of the science and research element of ESA's Living Planet Programme, providing an important contribution to the understanding of the Earth system. Following the User Consultation Meeting held in Graz, Austria on 5-6 March 2013, the Earth Science Advisory Committee (ESAC) has recommended implementing Biomass as the 7th Earth Explorer Mission within the frame of the ESA Earth Observation Envelope Programme. This paper will give an overview of the satellite system and its payload. The system technical description presented here is based on the results of the work performed during parallel Phase A system studies by two industrial consortia led by EADS Astrium Ltd. and Thales Alenia Space Italy. Two implementation concepts (respectively A and B) are described and provide viable options capable of meeting the mission requirements.

  7. ISO, ESA's explorer of the Unknown

    NASA Astrophysics Data System (ADS)

    1995-11-01

    Some burning questions left open in many fields of astrophysics, from nearby planets to the most distant quasars, taking in star formation, the dark matter of the universe and superluminous galaxies should find clues. The 5,3m high satellite will be commanded into its 24h eccentric orbit by ESA's space operations centre in Darmstadt (Germany). In its final orbit the spacecraft will pass as close as 1000 km to the Earth and go as far as 70,500 km. After the first signal from the satellite has been received, 45 minutes after the launch, the spacecraft controllers will switch on the systems and instruments on board over the next 72 hours before handing the control of the satellite over to Science Control Center located at ESA's Villafranca ground station near Madrid. A fully international team of 100 or so operations engineers and scientists will monitor and control the satellite from some 18 months of operational life time. Reflecting the project's international dimension, American and Japanese scientists will be co-located at its operations center and the NASA station at Goldstone, California, will relay communications when the satellite is out of Europe's ground station view. Full coverage will be provided with real-time links, making it possible to carry out observations for 16hrs per day when the observatory is outside the radiation belts. The building of the satellite has been an engineering challenge to the European Space industry and "will be the culmination of twelve years of intensive effort to build the most powerful and precise infrared space observatory to date", Prof. Bonnet, Director of ESA's Science Programme, said. The media are kindly invited to participate in the launch event in ESA's European --Space Operations Centre (ESOC) where the main press information center will be located. The launch can also be followed in other establishments where the respective PR officers can be contacted.

  8. Lunar Exploration and Science in ESA

    NASA Astrophysics Data System (ADS)

    Carpenter, James; Foing, Bernard H.; Fisackerly, Richard; Houdou, Berengere; De Rosa, Diego; Patti, Bernado; Schiemann, Jens

    ESA seeks to provide Europe with access to the lunar surface, and allow Europeans to benefit from the opening up of this new frontier, as part of a global endeavor. This will be best achieved through an exploration programme which combines the strengths and capabilities of both robotic and human explorers. ESA is preparing for future participation in lunar exploration through a combination of human and robotic activities, in cooperation with international partners. Future planned activities include the contribution of key technological capabilities to the Russian led robotic missions, Luna-Glob, Luna-Resurs orbiter and Luna-Resurs lander. For the Luna-Resurs lander ESA will provide analytical capabilities to compliment the already selected Russian led payload, focusing on the abundance, composition and isotopes of lunar volatiles in polar regions, and their associated chemistry. This should be followed by the contributions at the level of mission elements to a Lunar Polar Sample Return mission. This partnership will provide access for European investigators to the opportunities offered by the Russian led instruments on the missions, as well as providing Europe with a unique opportunity to characterise and utilise polar volatile populations. Ultimately samples of high scientific value, from as of yet unexplored and unsampled locations shall be made available to the scientific community. These robotic activities are being performed with a view to enabling a future more comprehensive programme in which robotic and human activities are integrated to provide the maximum benefits from lunar surface access. Activities on the ISS and ESA participation to the US Multi-Purpose Crew Vehicle, which is planned for a first unmanned lunar flight in 2017, are also important steps towards achieving this. All of these activities are performed with a view to generating the technologies, capabilities, knowledge and heritage that will make Europe an indispensable partner in the

  9. Lunar Exploration and Science in ESA

    NASA Astrophysics Data System (ADS)

    Carpenter, James; Houdou, Bérengère; Fisackerly, Richard; De Rosa, Diego; Patti, Bernardo; Schiemann, Jens; Hufenbach, Bernhard; Foing, Bernard

    2015-04-01

    ESA seeks to provide Europe with access to the lunar surface, and allow Europeans to benefit from the opening up of this new frontier, as part of a global endeavor. This will be best achieved through an exploration programme which combines the strengths and capabilities of both robotic and human explorers. ESA is preparing for future participation in lunar exploration through a combination of human and robotic activities, in cooperation with international partners. Future planned activities include the contribution of key technological capabilities to the Russian led robotic missions, Luna-Glob, Luna-Resurs orbiter and Luna-Resurs lander. For the Luna-Resurs lander ESA will provide analytical capabilities to compliment the Russian led science payload, focusing on developing an characterising the resource opportunities offered at the lunar surface. This should be followed by the contributions at the level of mission elements to a Lunar Polar Sample Return mission. These robotic activities are being performed with a view to enabling a future more comprehensive programme in which robotic and human activities are integrated to provide the maximum benefits from lunar surface access. Activities on the ISS and ESA participation to the US led Multi-Purpose Crew Vehicle, which is planned for a first unmanned lunar flight in 2017, are also important steps towards achieving this. In the frame of a broader future international programme under discussion through the International Space Exploration Coordination Group (ISECG) future missions are under investigation that would provide access to the lunar surface through international cooperation and human-robotic partnerships.

  10. Lunar Exploration and Science in ESA

    NASA Astrophysics Data System (ADS)

    Carpenter, James; Houdou, Bérengère; Fisackerly, Richard; De Rosa, Diego; Patti, Bernardo; Schiemann, Jens; Hufenbach, Bernhard; Foing, Bernard

    2014-05-01

    ESA seeks to provide Europe with access to the lunar surface, and allow Europeans to benefit from the opening up of this new frontier, as part of a global endeavor. This will be best achieved through an exploration programme which combines the strengths and capabilities of both robotic and human explorers. ESA is preparing for future participation in lunar exploration through a combination of human and robotic activities, in cooperation with international partners. Future planned activities include the contribution of key technological capabilities to the Russian led robotic missions, Luna-Glob, Luna-Resurs orbiter and Luna-Resurs lander. For the Luna-Resurs lander ESA will provide analytical capabilities to compliment the already selected Russian led payload, focusing on the composition and isotopic abundances of lunar volatiles in polar regions. This should be followed by the contributions at the level of mission elements to a Lunar Polar Sample Return mission. This partnership will provide access for European investigators to the opportunities offered by the Russian led instruments on the missions, as well as providing Europe with a unique opportunity to characterize and utilize polar volatile populations. Ultimately samples of high scientific value, from as of yet unexplored and unsampled locations shall be made available to the scientific community. These robotic activities are being performed with a view to enabling a future more comprehensive programme in which robotic and human activities are integrated to provide the maximum benefits from lunar surface access. Activities on the ISS and ESA participation to the US led Multi-Purpose Crew Vehicle, which is planned for a first unmanned lunar flight in 2017, are also important steps towards achieving this. All of these activities are performed with a view to generating the technologies, capabilities, knowledge and heritage that will make Europe an indispensable partner in the exploration missions of the future.

  11. Lunar Exploration and Science in ESA

    NASA Astrophysics Data System (ADS)

    Carpenter, J.; Houdou, B.; Fisackerly, R.; De Rosa, D.; Espinasse, S.; Hufenbach, B.

    2013-09-01

    Lunar exploration continues to be a priority for the European Space Agency (ESA) and is recognized as the next step for human exploration beyond low Earth orbit. The Moon is also recognized as an important scientific target providing vital information on the history of the inner solar system; Earth and the emergence of life, and fundamental information on the formation and evolution of terrestrial planets. The Moon also provides a platform that can be utilized for fundamental science and to prepare the way for exploration deeper into space and towards a human Mars mission, the ultimate exploration goal. Lunar missions can also provide a means of preparing for a Mars sample return mission, which is an important long term robotic milestone. ESA is preparing for future participation in lunar exploration through a combination of human and robotic activities, in cooperation with international partners. These include activities on the ISS and participation with US led Multi-Purpose Crew Vehicle, which is planned for a first unmanned lunar flight in 2017. Future activities planned activities also include participation in international robotic missions. These activities are performed with a view to generating the technologies, capabilities, knowledge and heritage that will make Europe an indispensible partner in the exploration missions of the future. We present ESA's plans for Lunar exploration and the current status of activities. In particular we will show that this programme gives rise to unique scientific opportunities and prepares scientifically and technologically for future exploratory steps.

  12. ESA Human rating Requirements:Status

    NASA Astrophysics Data System (ADS)

    Trujillo, M.; Sgobba, T.

    2012-01-01

    The European Space Agency (ESA) human rating safety requirements are based on heritage requirements of the International Space Station as well as the knowledge and experience derived from European participation on international partnerships. This expertise in conjunction with recommendations derived from past accidents (i.e.: Columbia) and lessons learned have led to the identification of m inimum core safety tech nical requirements for hum an rated space syst ems. These requirements apply to th e crewed space vehicle, integrated space system (i.e.: cre wed vehicle on its launcher) and its interfaces with control centres, la unch pad, etc. In 2009, a first draft was issued. Then, in the summer of 2010, ESA established a working group comprised of more than twenty experts (from disciplines including propulsion, pyrotechnics, structures, avionics, human factors and life support among others) across the Agency to review this draft. This paper provides an overview of ESA "Safety technical re quirements for human rated s pace systems" document, its scope a nd structure, as well as the planned steps for verification of these requirements in term s of achieving the identified safety objectives for crew safety in t erms of a quantitative risk evaluation.

  13. Ti3C2 MXenes with Modified Surface for High-Performance Electromagnetic Absorption and Shielding in the X-Band.

    PubMed

    Han, Meikang; Yin, Xiaowei; Wu, Heng; Hou, Zexin; Song, Changqing; Li, Xinliang; Zhang, Litong; Cheng, Laifei

    2016-08-17

    Electromagnetic (EM) absorbing and shielding composites with tunable absorbing behaviors based on Ti3C2 MXenes are fabricated via HF etching and annealing treatment. Localized sandwich structure without sacrificing the original layered morphology is realized, which is responsible for the enhancement of EM absorbing capability in the X-band. The composite with 50 wt % annealed MXenes exhibits a minimum reflection loss of -48.4 dB at 11.6 GHz, because of the formation of TiO2 nanocrystals and amorphous carbon. Moreover, superior shielding effectiveness with high absorption effectiveness is achieved. The total and absorbing shielding effectiveness of Ti3C2 MXenes in a wax matrix with a thickness of only 1 mm reach values of 76.1 and 67.3 dB, while those of annealed Ti3C2 MXenes/wax composites are 32 and 24.2 dB, respectively. Considering the promising performance of Ti3C2 MXenes with the modified surface, this work is expected to open the door for the expanded applications of MXenes family in EM absorbing and shielding fields. PMID:27454148

  14. Modeling of collision-induced infrared absorption spectra of H2 pairs in the first overtone band at temperatures from 20 to 500 K

    NASA Technical Reports Server (NTRS)

    Zheng, Chunguang; Borysow, Aleksandra

    1995-01-01

    A simple formalism is presented that permits quick computations of the low-resolution, rotovibrational collision-induced absorption (RV CIA) spectra of H2 pairs in the first overtone band of hydrogen, at temperatures from 20 to 500 K. These spectra account for the free-free transitions. The sharp dimer features, originating from the bound-free, free-bound, and bound-bound transitions are ignored, though their integrated intensities are properly accounted for. The method employs spectral model line- shapes with parameters computed from the three lowest spectral moments. The moments are obtained from first principles expressed as analytical functions of temperature. Except for the sharp dimer features, which are absent in this model, the computed spectra reproduce closely the results of exact quantum mechanical lineshape computations. Comparisons of the computed spectra with existing experimental data also show good agreement. The work interest for the modeling of the atmospheres of the outer planets in the near-infrared region of the spectrum. The user-friendly Fortran program developed here is available on request from the authors.

  15. Inhomogeneous broadening and peak shift of the 7.6 eV optical absorption band of oxygen vacancies in SiO{sub 2}

    SciTech Connect

    Kajihara, Koichi; Skuja, Linards; Hosono, Hideo

    2014-10-21

    The peak parameters of radiation-induced 7.6 eV optical absorption band of oxygen vacancies (Si-Si bonds) were examined for high-purity synthetic α-quartz and amorphous SiO{sub 2} (a‐SiO{sub 2}) exposed to {sup 60}Co γ-rays. The peak shape is asymmetric with the steeper edge at the lower energy side both in α-quartz and a‐SiO{sub 2}, and the peak energy is larger for α-quartz than that for a‐SiO{sub 2}. The full width at half maximum for a‐SiO{sub 2} is larger by ∼40-60% than that for α-quartz, and it increases with an increase in the disorder of the a‐SiO{sub 2} network, which is enhanced by raising the temperature of preannealing before irradiation, i.e., fictive temperature. These data are interpreted from the viewpoint of the site-to-site distribution of the Si-Si bond length in a‐SiO{sub 2}.

  16. The relationship of temperature rise to specific absorption rate and current in the human leg for exposure to electromagnetic radiation in the high frequency band.

    PubMed

    Wainwright, P R

    2003-10-01

    Of the biological effects of human exposure to radiofrequency and microwave radiation, the best-established are those due to elevation of tissue temperature. To prevent harmful levels of heating, restrictions have been proposed on the specific absorption rate (SAR). However, the relationship between SAR and temperature rise is not an invariant, since not only the heat capacity but also the efficiency of heat dissipation varies between different tissues and exposure scenarios. For small enough SAR, the relationship is linear and may be characterized by a 'heating factor' deltaT/SAR. Under whole-body irradiation the SAR may be particularly high in the ankles due to the concentration of current flowing through a relatively small cross-sectional area. In a previous paper, the author has presented calculations of the SAR distribution in a human leg in the high frequency (HF) band. In this paper, the heating factor for this situation is derived using a finite element approximation of the Pennes bioheat equation. The sensitivity of the results to different blood perfusion rates is investigated, and a simple local thermoregulatory model is applied. Both time-dependent and steady-state solutions are considered. Results confirm the appropriateness of the ICNIRP reference level of 100 mA on current through the leg, but suggest that at higher currents significant thermoregulatory adjustments to muscle blood flow will occur. PMID:14579857

  17. Proposal of high efficiency solar cells with closely stacked InAs/In{sub 0.48}Ga{sub 0.52}P quantum dot superlattices: Analysis of polarized absorption characteristics via intermediate–band

    SciTech Connect

    Yoshikawa, H. Kotani, T.; Kuzumoto, Y.; Izumi, M.; Tomomura, Y.; Hamaguchi, C.

    2014-07-07

    We present a theoretical study of the electronic structures and polarized absorption properties of quantum dot superlattices (QDSLs) using wide–gap matrix material, InAs/In{sub 0.48}Ga{sub 0.52}P QDSLs, for realizing intermediate–band solar cells (IBSCs) with two–step photon–absorption. The plane–wave expanded Burt–Foreman operator ordered 8–band k·p theory is used for this calculation, where strain effect and piezoelectric effect are taken into account. We find that the absorption spectra of the second transitions of two–step photon–absorption can be shifted to higher energy region by using In{sub 0.48}Ga{sub 0.52}P, which is lattice–matched material to GaAs substrate, as a matrix material instead of GaAs. We also find that the transverse magnetic polarized absorption spectra in InAs/In{sub 0.48}Ga{sub 0.52}P QDSL with a separate IB from the rest of the conduction minibands can be shifted to higher energy region by decreasing the QD height. As a result, the second transitions of two–step photon–absorption by the sunlight occur efficiently. These results indicate that InAs/In{sub 0.48}Ga{sub 0.52}P QDSLs are suitable material combination of IBSCs toward the realization of ultrahigh efficiency solar cells.

  18. The ESA's Space Trajectory Analysis software suite

    NASA Astrophysics Data System (ADS)

    Ortega, Guillermo

    The European Space Agency (ESA) initiated in 2005 an internal activity to develop an open source software suite involving university science departments and research institutions all over the world. This project is called the "Space Trajectory Analysis" or STA. This article describes the birth of STA and its present configuration. One of the STA aims is to promote the exchange of technical ideas, and raise knowledge and competence in the areas of applied mathematics, space engineering, and informatics at University level. Conceived as a research and education tool to support the analysis phase of a space mission, STA is able to visualize a wide range of space trajectories. These include among others ascent, re-entry, descent and landing trajectories, orbits around planets and moons, interplanetary trajectories, rendezvous trajectories, etc. The article explains that STA project is an original idea of the Technical Directorate of ESA. It was born in August 2005 to provide a framework in astrodynamics research at University level. As research and education software applicable to Academia, a number of Universities support this development by joining ESA in leading the development. ESA and Universities partnership are expressed in the STA Steering Board. Together with ESA, each University has a chair in the board whose tasks are develop, control, promote, maintain, and expand the software suite. The article describes that STA provides calculations in the fields of spacecraft tracking, attitude analysis, coverage and visibility analysis, orbit determination, position and velocity of solar system bodies, etc. STA implements the concept of "space scenario" composed of Solar system bodies, spacecraft, ground stations, pads, etc. It is able to propagate the orbit of a spacecraft where orbital propagators are included. STA is able to compute communication links between objects of a scenario (coverage, line of sight), and to represent the trajectory computations and

  19. Drug Safety Communication: Erythropoiesis-Stimulating Agents (ESAs)

    MedlinePlus

    ... ESAs) to be prescribed and used under a risk management program, known as a risk evaluation and mitigation ... the manufacturer of these products, to develop a risk management program because studies show that ESAs can increase ...

  20. Absorption intensity changes and frequency shifts of fundamental and first overtone bands for OH stretching vibration of methanol upon methanol-pyridine complex formation in CCl4: analysis by NIR/IR spectroscopy and DFT calculations.

    PubMed

    Futami, Yoshisuke; Ozaki, Yasushi; Ozaki, Yukihiro

    2016-02-21

    Infrared (IR) and near infrared (NIR) spectra were measured for methanol and the methanol-pyridine complex in carbon tetrachloride. Upon the formation of the methanol-pyridine complex, the frequencies of both the fundamental and first overtone bands of the OH stretching vibration shifted to lower frequencies, and the absorption intensity of the fundamental increased significantly, while that of the first overtone decreased markedly. By using quantum chemical calculations, we estimated the absorption intensities and frequencies of the fundamental and first overtone bands for the OH stretching vibration based on the one-dimensional Schrödinger equation. The calculated results well reproduced the experimental results. The molecular vibration potentials and dipole moment functions of the OH stretching vibration modes were compared between methanol and the methanol-pyridine complex in terms of absorption intensity changes and frequency shifts. The large change in the dipole moment function was found to be the main cause for the variations in absorption intensity for the fundamental and first overtone bands. PMID:26862859

  1. The origin of inverse absorption bands observed in the far-infrared RAIRS spectra of SnCl 4 and SnBr 4 adsorbed on thin-film SnO 2 surfaces

    NASA Astrophysics Data System (ADS)

    Awaluddin, A.; Pilling, M. J.; Wincott, P. L.; LeVent, S.; Surman, M.; Pemble, M. E.; Gardner, P.

    2002-04-01

    The adsorption of SnCl 4 and SnBr 4 on polycrystalline SnO 2 has been studied using synchrotron radiation based far-infrared reflection absorption infrared spectroscopy FIR-RAIRS. In order to exploit the sensitivity advantages of the buried metal layer method, the SnO 2 is in the form of a thin film deposited on a tungsten foil substrate. Adsorption of SnCl 4 and SnBr 4 on an oxygen sputtered surface at 120 K results in spectra characteristic of condensed multilayers. In addition, both spectra exhibit an inverse absorption band centred at 355 cm -1. Modified 4-layer, wavelength-dependent, Greenler calculations show that this inverse absorption band is induced by the presence of the adsorbate but is characteristic of the SnO 2 layer. The lack of any frequency shift upon changing the adsorbate from SnCl 4 to SnBr 4 rules out the possibility that the inverse absorption band is due to a dipole-forbidden parallel mode of the molecule excited via the interaction with free electron oscillations in the metal, resulting from the radiation induced oscillating electric field just below the surface.

  2. Second space Christmas for ESA: Huygens to begin its final journey to Titan/ Media activities.

    NASA Astrophysics Data System (ADS)

    2004-12-01

    your mail box! Messages from earthlings and pop music heading to Titan Before the mission was launched, ESA offered Europeans a unique opportunity to send a message to the unknown. Over 80 000 people wanted to share the excitement of this mission and wrote or drew a message that was engraved on a CD-ROM put on board the Huygens probe. The messages can be seen on http://television.esa.int/Huygens/index.cfm The same CD ROM carries four pop songs, composed by French musicians Julien Civange and Louis Haéri. More about this project at http://www.music2titan.com Specific information for media representatives going to ESA/ESOC Getting there: The nearest airport is Frankfurt-am-Main and it takes about 20 minutes by taxi to get to ESA/ESOC. A shuttle bus is also available from the airport approximately every 30 minutes. There are also frequent trains (approx. every 40 minutes) from the airport to Darmstadt (one change). http://www.heag.de/verkehr/02_02.html http://www.bahn.de/pv/view/index.shtml Accommodation: Darmstadt has many hotels, ranging in price from € 68 to € 230 (the closest to ESA/ESOC is a 4-star Maritim Konferenz Hotel, in walking distance from the Control Centre). For further information about Darmstadt hotels go to http://www.proregio-darmstadt.de/uebernachten/hotel.asp. If you need help with accommodation, do not hesitate to contact the ESA/ESOC travel office on +49(0)6151.902.885. Laptops/ Internet/ Cell Phones: Power supply rating: 220-240 volts (adaptor plug available in most hardware stores or at most international airport shops). Most North American cell phones will not work in Europe unless they are tri-band phones. Internet via LAN: Standard network connector RJ45 required in laptop. Internet via analogue modem: Standard RJ11 connector in laptop, special German Telekom TAE connection to the socket. Internet via ISDN: PCMCIA Card inside Laptop, RJ45 in the wall. The ESA/ESOC Press Rooms are equipped with ISDN and standard network with RJ45 cable. No

  3. Lunar Exploration and Science Opportunities in ESA

    NASA Astrophysics Data System (ADS)

    Carpenter, J.; Houdou, B.; Fisackerly, R.; De Rosa, D.; Schiemann, J.; Patti, B.; Foing, B.

    2014-04-01

    ESA seeks to provide Europe with access to the lunar surface, and allow Europeans to benefit from the opening up of this new frontier, as part of a global endeavour. This will be best achieved through an exploration programme which combines the strengths and capabilities of both robotic and human explorers. ESA is preparing for future participation in lunar exploration through a combination of human and robotic activities, in cooperation with international partners. Future planned activities include the contribution of key technological capabilities to the Russian led robotic missions, Luna-Glob, Luna-Resurs orbiter and Luna-Resurs lander. For the Luna-Resurs lander ESA will provide analytical capabilities to compliment the already selected Russian led payload, focusing on the composition and isotopic abundances of lunar volatiles in polar regions. This should be followed by the contributions at the level of mission elements to a Lunar Polar Sample Return mission. This partnership will provide access for European investigators to the opportunities offered by the Russian led instruments on the missions, as well as providing Europe with a unique opportunity to characterize and utilize polar volatile populations. Ultimately samples of high scientific value, from as of yet unexplored and unsampled locations shall be made available to the scientific community. These robotic activities are being performed with a view to enabling a future more comprehensive programme in which robotic and human activities are integrated to provide the maximum benefits from lunar surface access. Activities on the ISS and ESA participation to the US led Multi-Purpose Crew Vehicle, which is planned for a first unmanned lunar flight in 2017, are also important steps towards achieving this. All of these activities are performed with a view to generating the technologies, capabilities, knowledge and heritage that will make Europe an indispensible partner in the exploration missions of the future

  4. Lunar Exploration and Science in ESA

    NASA Astrophysics Data System (ADS)

    Carpenter, J.; Houdou, B.; Fisackerly, R.; De Rosa, D.; Patti, B.; Schiemann, J.; Hufenbach, B.; Foing, B.

    2014-04-01

    ESA seeks to provide Europe with access to the lunar surface, and allow Europeans to benefit from the opening up of this new frontier, as part of a global endeavor. This will be best achieved through an exploration programme which combines the strengths and capabilities of both robotic and human explorers. ESA is preparing for future participation in lunar exploration through a combination of human and robotic activities, in cooperation with international partners. Future planned activities include the contribution of key technological capabilities to the Russian led robotic missions, Luna-Glob, Luna-Resurs orbiter and Luna-Resurs lander. For the Luna-Resurs lander ESA will provide analytical capabilities to compliment the already selected Russian led payload, focusing on the composition and isotopic abundances of lunar volatiles in polar regions. This should be followed by the contributions at the level of mission elements to a Lunar Polar Sample Return mission. This partnership will provide access for European investigators to the opportunities offered by the Russian led instruments on the missions, as well as providing Europe with a unique opportunity to characterize and utilize polar volatile populations. Ultimately samples of high scientific value, from as of yet unexplored and unsampled locations shall be made available to the scientific community. These robotic activities are being performed with a view to enabling a future more comprehensive programme in which robotic and human activities are integrated to provide the maximum benefits from lunar surface access. Activities on the ISS and ESA participation to the US led Multi-Purpose Crew Vehicle, which is planned for a first unmanned lunar flight in 2017, are also important steps towards achieving this. All of these activities are performed with a view to generating the technologies, capabilities, knowledge and heritage that will make Europe an indispensible partner in the exploration missions of the future

  5. The ESA earth observation polar platform programme

    NASA Astrophysics Data System (ADS)

    Rast, M.; Readings, C. J.

    1991-08-01

    The overall scenario of ESA earth observation polar platform program is reviewed with particular attention given to instruments currently being considered for flight on the first European polar platforms. The major objectives of the mission include monitoring the earth's environment on various scales; management and monitoring of the earth's resources; improvement of the service provided to the worldwide operational meteorological community, investigation of the structure and dynamics of the earth's crust and interior. The program encompasses four main elements: an ERS-1 follow-on mission (ERS-2), a solid earth gravity mission (Aristoteles), a Meteosat Second Generation, and a series of polar orbit earth observation missions.

  6. A neural network-based four-band model for estimating the total absorption coefficients from the global oceanic and coastal waters

    NASA Astrophysics Data System (ADS)

    Chen, Jun; Cui, Tingwei; Quan, Wenting

    2015-01-01

    this study, a neural network-based four-band model (NNFM) for the global oceanic and coastal waters has been developed in order to retrieve the total absorption coefficients a(λ). The applicability of the quasi-analytical algorithm (QAA) and NNFM models is evaluated by five independent data sets. Based on the comparison of a(λ) predicted by these two models with the field measurements taken from the global oceanic and coastal waters, it was found that both the QAA and NNFM models had good performances in deriving a(λ), but that the NNFM model works better than the QAA model. The results of the QAA model-derived a(λ), especially in highly turbid waters with strong backscattering properties of optical activity, was found to be lower than the field measurements. The QAA and NNFM models-derived a(λ) could be obtained from the MODIS data after atmospheric corrections. When compared with the field measurements, the NNFM model decreased by a 0.86-24.15% uncertainty (root-mean-square relative error) of the estimation from the QAA model in deriving a(λ) from the Bohai, Yellow, and East China seas. Finally, the NNFM model was applied to map the global climatological seasonal mean a(443) for the time range of July 2002 to May 2014. As expected, the a(443) value around the coastal regions was always larger than the open ocean around the equator. Viewed on a global scale, the oceans at a high latitude exhibited higher a(443) values than those at a low latitude.

  7. Screened coulomb hybrid DFT investigation of band gap and optical absorption predictions of CuVO3, CuNbO3 and Cu5Ta11O30 materials.

    PubMed

    Harb, Moussab; Masih, Dilshad; Takanabe, Kazuhiro

    2014-09-14

    We present a joint theoretical and experimental investigation of the optoelectronic properties of CuVO3, CuNbO3 and Cu5Ta11O30 materials for potential photocatalytic and solar cell applications. In addition to the experimental results obtained by powder X-ray diffraction and UV-Vis spectroscopy of the materials synthesized under flowing N2 gas at atmospheric pressure via solid-state reactions, the electronic structure and the UV-Vis optical absorption coefficient of these compounds are predicted with high accuracy using advanced first-principles quantum methods based on DFT (including the perturbation theory approach DFPT) within the screened coulomb hybrid HSE06 exchange-correlation formalism. The calculated density of states are found to be in agreement with the UV-Vis diffuse reflectance spectra, predicting a small indirect band gap of 1.4 eV for CuVO3, a direct band gap of 2.6 eV for CuNbO3, and an indirect (direct) band gap of 2.1 (2.6) eV for Cu5Ta11O30. It is confirmed that the Cu(I)-based multi-metal oxides possess a strong contribution of filled Cu(I) states in the valence band and of empty d(0) metal states in the conduction band. Interestingly, CuVO3 with its predicted small indirect band gap of 1.4 eV shows the highest absorption coefficient in the visible range with a broad absorption edge extending to 886 nm. This novel result offers a great opportunity for this material to be an excellent candidate for solar cell applications. PMID:25055167

  8. ATLID, ESA Atmospheric LIDAR Developement Status

    NASA Astrophysics Data System (ADS)

    Pereira do Carmo, João; Hélière, Arnaud; Le Hors, L.; Toulemont, Y.; Lefebvre, A.

    2016-06-01

    The ATmospheric LIDAR ATLID[1] is part of the payload of the Earth Cloud and Aerosol Explorer[2] (EarthCARE) satellite mission, the sixth Earth Explorer Mission of the European Space Agency (ESA) Living Planet Programme. EarthCARE is a joint collaborative satellite mission conducted between ESA and the National Space Development Agency of Japan (JAXA) that delivers the Cloud Profiling Radar (CPR) instrument. The payload consists of four instruments on the same platform with the common goal to provide a picture of the 3D-dimensional spatial and the temporal structure of the radiative flux field at the top of atmosphere, within the atmosphere and at the Earth's surface. This paper is presenting an updated status of the development of the ATLID instrument and its subsystem design. The instrument has recently completed its detailed design, and most of its subsystems are already under manufacturing of their Flight Model (FM) parts and running specific qualification activities. Clouds and aerosols are currently one of the biggest uncertainties in our understanding of the atmospheric conditions that drive the climate system. A better modelling of the relationship between clouds, aerosols and radiation is therefore amongst the highest priorities in climate research and weather prediction.

  9. ESA situational awareness of space weather

    NASA Astrophysics Data System (ADS)

    Luntama, Juha-Pekka; Glover, Alexi; Keil, Ralf; Kraft, Stefan; Lupi, Adriano

    2016-07-01

    ESA SSA Period 2 started at the beginning of 2013 and will last until the end of 2016. For the Space Weather Segment, transition to Period 2 introduced an increasing amount of development of new space weather service capability in addition to networking existing European assets. This transition was started already towards the end of SSA Period 1 with the initiation of the SSA Space Weather Segment architecture definition studies and activities enhancing existing space weather assets. The objective of Period 2 has been to initiate SWE space segment developments in the form of hosted payload missions and further expand the federated service network. A strong focus has been placed on demonstration and testing of European capabilities in the range of SWE service domains with a view to establishing core products which can form the basis of SWE service provision during SSA Period 3. This focus has been particularly addressed in the SSA Expert Service Centre (ESC) Definition and Development activity that was started in September 2015. This presentation will cover the current status of the SSA SWE Segment and the achievements during SSA Programme Periods 1 and 2. Particular attention is given to the federated approach that allow building the end user services on the best European expertise. The presentation will also outline the plans for the Space Weather capability development in the framework of the ESA SSA Programme in 2017-2020.

  10. Successful communications test for ESA's Mars Express

    NASA Astrophysics Data System (ADS)

    2003-10-01

    Mars Express in orbit around Mars hi-res Size hi-res: 592 kb Credits: ESA - Illustration by Medialab Mars Express in orbit around Mars Mars Express will left Earth for Mars in June 2003 when the positions of the two planets made for the shortest possible route, a condition that occurs once every twenty-six months. The intrepid spacecraft started its six-month journey from the Baikonur launch pad in Kazakhstan onboard a Russian Soyuz/Fregat launcher. Mars Express began the six-month interplanetary cruise at a velocity of 10 800 km/h relative to Earth. Five days before arrival in December 2003, Mars Express will eject the Beagle 2 lander, which will make its own way to the correct landing site on the surface. The orbiter will then manoeuvre into a highly elliptical capture orbit, from which it can move into its operational near-polar orbit. communications test Mars Express The MELACOM system is designed to communicate with Beagle 2, passing the lander's data to Mars Express's main antenna for relaying to Earth. The MELACOM test was done in collaboration between sites at Stanford (USA), New Norcia (Australia) and ESA's Space Operations Centre (ESOC) in Darmstadt, Germany. The 34-metre dish at Stanford pretended to be Beagle 2, using its greater size to overcome the large distance between Earth and the spacecraft. The test consisted of two sessions, a first one in which the Stanford's signal was sent to Mars Express's MELACOM, and a second one in which MELACOM sent a signal back to Stanford. Con McCarthy, ESA's Beagle 2 manager, who supervised the operation, said: "We were on a hilltop, outside San Francisco. It was 4:10 UT and Mars was clearly visible in the sky. The Stanford dish tracked Mars Express slowly, transmitting to it for 40 minutes." Then the spacecraft re-oriented itself to point its main antenna to Earth to confirm it had received the signal. The confirmation was received by ESA's New Norcia ground station and relayed to ESOC. Following this, at 6:10 UT

  11. Future lunar exploration activities in ESA

    NASA Astrophysics Data System (ADS)

    Houdou, B.; Carpenter, J. D.; Fisackerly, R.; Koschny, D.; Pradier, A.; di Pippo, S.; Gardini, B.

    2009-04-01

    Introduction Recent years have seen a resurgence of interest in the Moon and various recent and coming orbital missions including Smart-1, Kaguya, Chandrayaan-1and Lunar Reconnaissance Orbiter are advancing our understanding. In 2004 the US announced a new Vision for Space Exploration [1], whose objectives are focused towards human missions to the Moon and Mars. The European Space Agency has established similar objectives for Europe, described in [2] and approved at the ESA ministerial council (2009). There is considerable potential for international cooperation in these activities, as formulated in the recently agreed Global Exploration Strategy [3]. Present lunar exploration activities at ESA emphasise the development of European technologies and capabilities, to enable European participation in future international human exploration of the Moon. A major element in this contribution has been identified as a large lunar cargo lander, which would fulfill an ATV-like function, providing logistical support to human activities on the Moon, extending the duration of sorties and the capabilities of human explorers. To meet this ultimate goal, ESA is currently considering various possible development approaches, involving lunar landers of different sizes. Lunar Lander Mission Options A high capacity cargo lander able to deliver consumables, equipment and small infrastructure, in both sortie and outpost mission scenarios, would use a full Ariane 5 launch and is foreseen in the 2020-2025 timeframe. ESA is also considering an intermediate, smaller-scale mission beforehand, to mature the necessary landing technologies, to demonstrate human-related capabilities in preparation of human presence on the Moon and in general to gain experience in landing and operating on the lunar surface. Within this frame, ESA is currently leading several feasibility studies of a small lunar lander mission, also called "MoonNEXT". This mission is foreseen to be to be launched from Kourou with a

  12. X-ray absorption and reflection as probes of the GaN conduction bands: Theory and experiment of the N K-edge and Ga M{sub 2,3} edges

    SciTech Connect

    Lambrecht, W.R.L.; Rashkeev, S.N.; Segall, B.; Lawniczak-Jablonska, K.; Suski, T.; Gullikson, E.M.; Underwood, J.H.; Perera, R.C.C.; Rife, J.C.

    1997-12-31

    X-ray absorption and glancing angle reflectivity measurements in the energy range of the Nitrogen K-edge and Gallium M{sub 2,3} edges are reported. Linear muffin-tin orbital band-structure and spectral function calculations are used to interpret the data. Polarization effects are evidenced for the N-K-edge spectra by comparing X-ray reflectivity in s- and p-polarized light.

  13. ESA Sea Level Climate Change Initiative

    NASA Astrophysics Data System (ADS)

    Larnicol, Gilles; Cazenave, Anny; Faugere, Yannice; Ablain, Michael; Johannessen, Johnny; Stammer, Detlef; Timms, Gary; Knudsen, Per; Cipollini, Paolo; Roca, Monica; Rudenko, Sergei; Fernandes, Joana; Balmaseda, Magdalena; Guinle, Thierry; Benveniste, Jerome

    2013-04-01

    Sea level is a very sensitive index of climate change and variability. As the ocean warms in response to global warming, sea waters expand and, as a result, sea level rises. When mountain glaciers melt in response to increasing air temperature, sea level rises because more freshwater glacial runoff discharges into the oceans. Similarly, ice mass loss from the ice sheets causes sea-level rise. Therefore, understanding the sea level variability and changes implies in addition to the understanding of the ocean variability and the exchanges between ocean, land, cryosphere, and atmosphere, an accurate monitoring of the sea level variable at climate scales. That is why Sea Level is one of the variables selected in the frame of the ESA Climate change Initiative (CCI) program initiated by ESA in July 2010. In overall, this program aims to provide an adequate, comprehensive, and timely response to the extremely challenging set of requirements for highly stable, long-term satellite-based products for climate, that have been addressed to Space Agencies via the Global Climate Observing System (GCOS) and the Committee on Earth Observation Satellites (CEOS). In order to achieve this global objective, the specific objectives of the sea level CCI project are: to involve the climate research community to collect their needs and feedbacks on product quality, to develop, test and select the best algorithms and standards to generate a climate time series (so called SL ECV products), and to provide a complete specification of the production system. After two of projects the first two objectives have been completed. Hereafter, we aim to provide an overview and the current status of the Sea Level project of the ESA Climate Change Initiative (CCI) that has started in july 2010. The main objective of this project is to produce and validate the Sea Level Essential Climate Variable (ECV) product. Two years after the project kick-off, the 20 Years of Progress in Radar Altimetry Symposium was

  14. ESA's Planetary Science Archive: Status and Plans

    NASA Astrophysics Data System (ADS)

    Heather, David; Barthelemy, Maud; Manaud, Nicolas; Martinez, Santa; Szumlas, Marek; Vazquez, Jose Luis; Arviset, Christophe; Osuna, Pedro; PSA Development Team

    2013-04-01

    Scientific and engineering data from ESA's planetary missions are made accessible to the world-wide scientific community via the Planetary Science Archive (PSA). The PSA consists of online services incorporating search, preview, download, notification and delivery basket functionality. The PSA currently holds data from Mars Express, Venus Express, SMART-1, Huygens, Rosetta and Giotto, as well as several ground-based cometary observations. It will be used for archiving on ExoMars, BepiColombo and for the European contributions to Chandrayaan-1. The focus of the PSA activities is on the long-term preservation of data and knowledge from ESA's planetary missions. Scientific users can access the data online using several interfaces: - The Advanced Search Interface allows complex parameter based queries, providing the end user with a facility to complete very specific searches on meta-data and geometrical parameters. - The Map-based Interface is currently operational only for Mars Express HRSC and OMEGA data. This interface allows an end-user to specify a region-of-interest by dragging a box onto a base map of Mars. From this interface, it is possible to directly visualize query results. The Map-based and Advanced interfaces are linked and cross-compatible. If a user defines a region-of-interest in the Map-based interface, the results can be refined by entering more detailed search parameters in the Advanced interface. - The FTP Browser Interface is designed for more experienced users, and allows for direct browsing and access of the data set content through ftp-tree search. Each dataset contains documentation and calibration information in addition to the scientific or engineering data. All PSA data are prepared by the corresponding instrument teams, and are made to comply with the internationally recognized PDS standards. PSA supports the instrument teams in the full archiving process, from the definition of the data products, meta-data and product labels through to

  15. NASA/ESA CV-990 spacelab simulation

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Due to interest in the application of simplified techniques used to conduct airborne science missions at NASA's Ames Research Center, a joint NASA/ESA endeavor was established to conduct an extensive Spacelab simulation using the NASA CV-990 airborne laboratory. The scientific payload was selected to perform studies in upper atmospheric physics and infrared astronomy with principal investigators from France, the Netherlands, England, and several groups from the United States. Communication links between the 'Spacelab' and a ground based mission operations center were limited consistent with Spacelab plans. The mission was successful and provided extensive data relevant to Spacelab objectives on overall management of a complex international payload; experiment preparation, testing, and integration; training for proxy operation in space; data handling; multiexperimenter use of common experimenter facilities (telescopes); multiexperiment operation by experiment operators; selection criteria for Spacelab experiment operators; and schedule requirements to prepare for such a Spacelab mission.

  16. An overview of ESA cryocooler activities

    NASA Astrophysics Data System (ADS)

    Jewell, C. I.

    1991-12-01

    With a significant number of future cryogenic cooling requirements incompatible with either radiative or cryogen cooling, a program of cryocooler developments which should lead to a range of 'space qualified' cryocoolers being commercially available for future users has been followed. An ESA 80 K 'Oxford type' cooler can presently be considered to be space qualified, while 20 and 4 K coolers are expected to be 'qualified' by 1992. Work is also being undertaken for the development of a 2.5 K cryocooler with 0.3 K as a future goal. The history of the 'Oxfordtype' cooler indicated that the design is based on an excellent pedigree and suggested future work should significantly increase the cryocoolers realm of applications.

  17. START Analysis for ESAS Capability Needs Prioritization

    NASA Technical Reports Server (NTRS)

    Lincoln, William; Mrozinski, Joe; Hua, Hook; Merida, Sofia; Shelton, Kacie; Adumitroaie, Virgil; Weisbin, Charles R.; Derleth, Jason

    2006-01-01

    START is a tool to optimize research and development primarily for NASA missions. It was developed within the Strategic Systems Technology Program Office, a division of the Office of the Chief Technologist at NASA's Jet Propulsion Laboratory. START is capable of quantifying and comparing the risks, costs, and potential returns of technologies that are candidates for funding. START can be enormously helpful both in selecting technologies for development -- within the constraints of budget, schedule, and other resources -- and in monitoring their progress. START's methods are applicable to everything from individual tasks to multiple projects comprising entire programs of investigation. They can address virtually any technology assessment and capability prioritization issue. In this report, START is used to analyze the capability needs using data from NASA's Exploration Systems Architecture Study (ESAS).

  18. ESA unveils Spanish antenna for unique space mission

    NASA Astrophysics Data System (ADS)

    2000-05-01

    The newly refurbished antenna, which is located at the Villafranca del Castillo Satellite Tracking Station site (VILSPA) near Madrid, has been selected as the prime communication link with the Cluster II spacecraft. The VIL-1 antenna will play a vital role in ESA's Cluster mission by monitoring and controlling the four spacecraft and by receiving the vast amounts of data that will be returned to Earth during two years of operations. Scheduled for launch in summer 2000, the Cluster quartet will complete the most detailed investigation ever made into the interaction between our pl0anet's magnetosphere - the region of space dominated by Earth's magnetic field - and the continuous stream of charged particles emitted by the Sun - the solar wind. This exciting venture is now well under way, following completion of the satellite assembly and test programme and two successful verification flights by the newly developed Soyuz-Fregat launch vehicle. The ESA Flight Acceptance Review Board has accordingly given the go-ahead for final launch preparations at the Baikonur Cosmodrome in Kazakhstan. VILSPA, ESA and Cluster II Built in 1975, after an international agreement between the European Space Agency and the Spanish government, VILSPA is part of the European Space Operations Centre (ESOC) Tracking Station Network (ESTRACK). In the last 25 years, VILSPA has supported many ESA and international satellite programmes, including the International Ultraviolet Explorer (IUE), EXOSAT and the Infrared Space Observatory (ISO). In addition to supporting the Cluster II mission, it has been designated as the Science Operations Centre for ESA's XMM Newton mission and for the Far-Infrared Space Telescope (FIRST), which is due to launch in 2007. There are now more than half a dozen large dish antennae installed at VILSPA. One of these is the VIL-1 antenna, a 15 metre diameter dish which operates in the S-band radio frequency (1.8 - 2.7 GHz). This antenna has been modernised recently in order

  19. The ESA standard for telemetry and telecommand packet utilisation: PUS

    NASA Astrophysics Data System (ADS)

    Kaufeler, Jean-Francois

    1994-11-01

    ESA has developed standards for packet telemetry and telecommand, which are derived from the recommendations of the Inter-Agency Consultative Committee for Space Data Systems (CCSDS). These standards are now mandatory for future ESA programs as well as for many programs currently under development. However, while these packet standards address the end-to-end transfer of telemetry and telecommand data between applications on the ground and Application Processes on-board, they leave open the internal structure or content of the packets. This paper presents the ESA Packet Utilization Standard (PUS) which addresses this very subject and, as such, serves to extend and complement the ESA packet standards. The goal of the PUS is to be applicable to future ESA missions in all application areas (Telecommunications, Science, Earth Resources, microgravity, etc.). The production of the PUS falls under the responsibility of the ESA Committee for Operations and EGSE Standards (COES).

  20. Spectroscopic evidence for the formation of singlet molecular oxygen (/sup 1/. delta. /sub g/O/sub 2/) upon irradiation of a solvent-oxygen (/sup 3/Sigma/sub g//sup -/O/sub 2/) cooperative absorption band

    SciTech Connect

    Scurlock, R.D.; Ogilby, P.R.

    1988-01-20

    It is well-known that the presence of molecular oxygen (/sup 3/..sigma../sub g//sup -/O/sub 2/) in a variety of organic solvents causes an often substantial red shift in the solvent absorption spectrum. This extra, broad absorption feature is reversibly removed by purging the solvent with nitrogen gas. Mulliken and Tsubomura assigned the oxygen-dependent absorption band to a transition from a ground state solvent-oxygen complex to a solvent-oxygen charge transfer (CT) state (sol/sup .+/O/sub 2//sup .-/). In addition to the broad Mulliken CT band, there are, often in the same spectral region, distinct singlet-triplet transitions (T/sub 1/ reverse arrow S/sub 0/) which are enhanced by molecular oxygen (/sup 3/..sigma../sub g//sup -/O/sub 2/). Since both of these solvent-oxygen cooperative transitions may result in the formation of reactive oxygenating species, singlet molecular oxygen (/sup 1/..delta../sub g/O/sub 2/) and/or the superoxide ion (O/sub 2//sup .-/), it follows that recent studies have focused on unsaturated hydrocarbon oxygenation subsequent to the irradiation of the oxygen-induced absorption bands in both the solution phase and cryogenic (10 K) glasses. In these particular experiments, oxygenated products characteristic of both /sup 1/..delta../sub g/O/sub 2/ and O/sub 2//sub .-/ were obtained, although the systems studied appeared to involve the participation of one intermediate at the exclusion of the other. In this communication, the authors provide, for the first time, direct spectroscopic evidence for the formation of /sup 1/..delta../sub g/O/sub 2/ following a solvent-oxygen (/sup 3/..sigma../sub g//sup -/O/sub 2/) cooperative absorption. They have observed, in a time-resolved experiment, a near-IR luminescence subsequent to laser excitation of the oxygen-induced absorption bands of mesitylene, p-xylene, o-xylene, toluene, and benzene at 355 nm and 1,4-dioxane at 266 nm. They suggest that this signal is due to /sup 1/..delta../sub g/O/sub 2

  1. NASA's Preparations for ESA's L3 Gravitational Wave Mission

    NASA Astrophysics Data System (ADS)

    Stebbins, Robin

    2016-03-01

    The European Space Agency (ESA) selected gravitational-wave astrophysics as the science theme for its third large mission opportunity, known as `L3,' under its Cosmic Vision Programme. NASA is seeking a role as an international partner in L3. NASA is: (1) participating in ESA's early mission activities, (2) developing potential US technology contributions, (3) participating in ESA's LISA Pathfinder mission, (4) and conducting a study of how NASA might participate. This talk will survey the status of these activities.

  2. Experimental and theoretical study of absorption spectrum of the (CH3)2CO···HF complex. Influence of anharmonic interactions on the frequency and intensity of the C=O and H-F stretching bands.

    PubMed

    Bulychev, V P; Svishcheva, E A; Tokhadze, K G

    2014-01-01

    IR absorption spectra of mixtures (CH3)2CO/HF and free (CH3)2CO molecules are recorded in the region of 4000-900 cm(-1) with a Bruker IFS-125 HR vacuum Fourier spectrometer at room temperature with a resolution up to 0.02 cm(-1). Spectral characteristics of the 2ν(C=O) overtone band of free acetone are reliably measured. The ν1(HF) and ν(C=O) absorption bands of the (CH3)2CO···HF complex are obtained by subtracting the absorption bands of free HF and acetone and absorption lines of atmospheric water from the experimental spectrum of mixtures. The experimental data are compared with theoretical results obtained from variational solutions of 1D-4D vibrational Schrödinger equations. The anharmonic potential energy and dipole moment surfaces used in the calculations were computed in the MP2/6-311++G(2d,2p) approximation with corrections for the basis set superposition error. Comparison of the data derived from solutions for different combinations of vibrational degrees of freedom shows that taking the inter-mode anharmonic interactions into account has different effects on the transition frequencies and intensities. Particular attention has been given to elucidation of the influence of anharmonic coupling of the H-F and C=O stretches with the low-frequency intermolecular modes on their frequencies and intensities and the strength of resonance between the fundamental H-F and the first overtone C=O transitions. PMID:24128921

  3. The GRB Investigations by ESA Satellite Gaia

    NASA Astrophysics Data System (ADS)

    Hudec, R.; Šimon, V.; Hudec, L.

    2009-05-01

    The ESA satellite in development Gaia to be launched in 2011 will focus on highly precise astrometry of stars and all objects down to limiting magnitude 20. Albeit focusing on astrometry related matters, the satellite will also provide photometric and spectral information and hence important inputs for various branches of astrophysics. Within the Gaia Variability UnitCU7 and related work package Specific Object Studies there has been a sub-work package accepted for optical counterparts to celestial high-energy sources, a category which includes the optical counterparts (i.e. optical transients and optical afterglows, including counterparts of XRFs and yet hypothetical orphan afterglows) of GRBs, and also microquasars. Although the sampling of photometric data will not be optimal for this type of work, the strength of Gaia in such analyses is the fine spectral resolution (spectro-photometry) which will allow the correct classification of related triggers. The possibilities to detect and to analyze optical transients and optical afterglows of GRBs and microquasars by Gaia will be presented and discussed.

  4. APEX - the Hyperspectral ESA Airborne Prism Experiment

    PubMed Central

    Itten, Klaus I.; Dell'Endice, Francesco; Hueni, Andreas; Kneubühler, Mathias; Schläpfer, Daniel; Odermatt, Daniel; Seidel, Felix; Huber, Silvia; Schopfer, Jürg; Kellenberger, Tobias; Bühler, Yves; D'Odorico, Petra; Nieke, Jens; Alberti, Edoardo; Meuleman, Koen

    2008-01-01

    The airborne ESA-APEX (Airborne Prism Experiment) hyperspectral mission simulator is described with its distinct specifications to provide high quality remote sensing data. The concept of an automatic calibration, performed in the Calibration Home Base (CHB) by using the Control Test Master (CTM), the In-Flight Calibration facility (IFC), quality flagging (QF) and specific processing in a dedicated Processing and Archiving Facility (PAF), and vicarious calibration experiments are presented. A preview on major applications and the corresponding development efforts to provide scientific data products up to level 2/3 to the user is presented for limnology, vegetation, aerosols, general classification routines and rapid mapping tasks. BRDF (Bidirectional Reflectance Distribution Function) issues are discussed and the spectral database SPECCHIO (Spectral Input/Output) introduced. The optical performance as well as the dedicated software utilities make APEX a state-of-the-art hyperspectral sensor, capable of (a) satisfying the needs of several research communities and (b) helping the understanding of the Earth's complex mechanisms.

  5. ESA activities in the use of microwaves for the remote sensing of the Earth

    NASA Technical Reports Server (NTRS)

    Maccoll, D.

    1984-01-01

    The program of activities under way in the European Space Agency (ESA) directed towards Remote Sensing of the oceans and troposphere is discussed. The initial project is the launch of a satellite named ERS-1 with a primary payload of microwave values in theee C- and Ku-bands. This payload is discussed in depth. The secondary payload includes precision location experiments and an instrument to measure sea surface temperature, which are described. The important topic of calibration is extensively discussed, and a review of activities directed towards improvements to the instruments for future satellites is presented. Some discussion of the impact of the instrument payload on the spacecraft design follows and the commitment of ESA to the provision of a service of value to the ultimate user is emphasized.

  6. The ESA Space Environment Information System (SPENVIS)

    NASA Astrophysics Data System (ADS)

    Heynderickx, D.; Quaghebeur, B.; Evans, H. D. R.

    2002-01-01

    The ESA SPace ENVironment Information System (SPENVIS) provides standardized access to models of the hazardous space environment through a user-friendly WWW interface. The interface includes parameter input with extensive defaulting, definition of user environments, streamlined production of results (both in graphical and textual form), background information, and on-line help. It is available on-line at http://www.spenvis.oma.be/spenvis/. SPENVIS Is designed to help spacecraft engineers perform rapid analyses of environmental problems and, with extensive documentation and tutorial information, allows engineers with relatively little familiarity with the models to produce reliable results. It has been developed in response to the increasing pressure for rapid-response tools for system engineering, especially in low-cost commercial and educational programmes. It is very useful in conjunction with radiation effects and electrostatic charging testing in the context of hardness assurance. SPENVIS is based on internationally recognized standard models and methods in many domains. It uses an ESA-developed orbit generator to produce orbital point files necessary for many different types of problem. It has various reporting and graphical utilities, and extensive help facilities. The SPENVIS radiation module features models of the proton and electron radiation belts, as well as solar energetic particle and cosmic ray models. The particle spectra serve as input to models of ionising dose (SHIELDOSE), Non-Ionising Energy Loss (NIEL), and Single Event Upsets (CREME). Material shielding is taken into account for all these models, either as a set of user-defined shielding thicknesses, or in combination with a sectoring analysis that produces a shielding distribution from a geometric description of the satellite system. A sequence of models, from orbit generator to folding dose curves with a shielding distribution, can be run as one process, which minimizes user interaction and

  7. From ESAS to Ares: A Chronology

    NASA Technical Reports Server (NTRS)

    Cook, Stephen A.

    2007-01-01

    Throughout my career, I have observed many launch vehicle efforts come and go. Although it may appear on the surface that those were dead-end streets, the knowledge we gained through them actually informs the work in progress. Following the tragic loss of the Space Shuttle Columbia's crew, the administration took the Columbia Accident Investigation Board's findings to heart and united the Agency behind the Vision for Space Exploration, with clear goals and objectives, including fielding a new generation of safe, reliable, and affordable space transportation. The genesis of the Ares I Crew Launch Vehicle and Ares V Cargo Launch Vehicle activities now under way by a nationwide Government and industry team was the confirmation of the current NASA Administrator in April 2005. Shortly thereafter, he commissioned a team of aerospace experts to conduct the Exploration Systems Architecture Study (ESAS), which gave shape to launch vehicles that will empower America's resurgence in scientific discovery through human and robotic space exploration. In October 2005, I was asked to lead this effort, building the team and forming the partnerships that will, in turn, build America's next human-rated space transportation system. In November 2006, the Ares I team began conducting the System Requirements Review milestone, just 1 year after its formation. We are gaining momentum toward the first test flight of the integrated vehicle system in 2009, just a few short years away. The Agency is now poised to deliver on the commitment this nation has made to advance our interests in space. In its inaugural year, the Ares team has conducted the first human-rated launch vehicle major milestone in over 30 years. Using the Exploration Systems Architecture Study recommendations as a starting point, the vehicle designs have been evolved to best meet customer and stakeholder requirements to fulfill the strategic goals outlined in the Vision for Space Exploration.

  8. ESA's Integral satellite ready for lift-off from Baikonur

    NASA Astrophysics Data System (ADS)

    2002-10-01

    ESA's INTEGRAL (International Gamma Ray Astrophysics Laboratory) satellite, will be launched by a Proton launcher from Baikonur, Kazakhstan on 17 October at 06:41 CEST (Central European Summer Time). The most sensitive gamma-ray observatory ever launched, INTEGRAL is a truly international mission involving all ESA member states plus the USA and Russia. It carries four instruments from teams led by scientists in Italy, France, Germany, Denmark and Spain to gather and analyse gamma-rays, X-rays and visible light from celestial objects. INTEGRAL will give astronomers across the world their clearest views yet of the most extreme environments in the Universe. It will detect radiation from the most violent events far away and from processes that made the Universe inhabitable. Media representatives in Europe can follow the videotransmission of the launch at ESA/Darmstadt (ESOC) in Germany, which will be acting as the main European press centre, ESA/Noordwijk (ESTEC) in the Netherlands, ESA/Frascati (ESRIN) in Italy or ESA/Villafranca (VILSPA) in Spain. At each site ESA specialists will be available for interviews. Media representatives wishing to attend are requested to complete the attached reply form and fax it to the Communication Office at the establishment of their choice. The ESA TV Service will provide video news releases and live coverage of the launch between 06:15-07:00 and 08:00-08:30 CEST. Details of the transmission schedule for the various Video News Releases can be found on http://television.esa.int The launch can also be followed live on the internet at www.esa.int/integrallaunch starting at 06:15 hrs.

  9. ESA Unveils Its New Comet Chaser.

    NASA Astrophysics Data System (ADS)

    1999-07-01

    The objective is to study one of these primordial objects at close quarters by placing a lander on its surface and chasing, with an orbiter, the comet for millions of kilometres through space. Comets - among the oldest (4.6 billion years!) and last altered objects in the solar system - are regarded as the building blocks from which the planets formed. Thus the Rosetta's discoveries will allow the scientists to learn more about birth and evolution of the planets and about the origin of life on the Earth. The final design of the Rosetta orbiter will be revealed for the first time at the Royal Society in London on 1 July when a 1:4 scale model will be unveiled by ESA's Director of Science, Prof.. Roger Bonnet. (The full size version of the spacecraft is 32 metres across, so large that it would stretch the entire width of a football pitch. Almost 90 of this is accounted for by the giant solar panels which are needed to provide electrical power in the dark depths of the Solar System). "Rosetta is a mission of major scientific importance," said Prof. Bonnet. "It will build on the discoveries made by Giotto and confirm ESA's leading role in the exploration of the Solar System and the Universe as a whole." The timing of this event has been chosen to coincide with the London meeting of the Rosetta Science Working Team and the second Earth flyby of the now non-operational Giotto spacecraft. In addition, the opening of the British Museum's 'Cracking Codes' Exhibition, for which the Rosetta Stone is the centrepiece, is set to take place on 10 July. The Rosetta mission. Rosetta is the third Cornerstone in ESA's 'Horizon 2000' long-term scientific programme. It will be launched by Ariane 5 rocket from Kourou spaceport in French Guiana in January 2003. In order to gain sufficient speed to reach the distant comet, Rosetta will require gravity assists from the Earth (twice) and Mars. After swinging around Mars in May 2005, Rosetta will return to Earth's vicinity in October 2005 and

  10. The two-photon absorptivity of rotational transitions in the A2 Sigma hyperon + (v prime = O) - X-2 pion (v prime prime = O) gamma band of nitric oxide

    NASA Technical Reports Server (NTRS)

    Gross, K. P.; Mckenzie, R. L.

    1982-01-01

    A predominantly single-mode pulsed dye laser system giving a well characterized spatial and temporal output suitable for absolute two-photon absorptivity measurements was used to study the NO gamma(0,0) S11 + R21 (J double prime = 7-1/2) transition. Using a calibrated induced-fluorescence technique, an absorptivity parameter of 2.8 + or - 1.4 x 10 to the minus 51st power cm to the 6th power was obtained. Relative strengths of other rotational transitions in the gamma(0,0) band were also measured and shown to compare well with predicted values in all cases except the O12 (J double prime = 10-1/2) transition.

  11. Intraband absorption in the 8-12 μm band from Si-doped vertically aligned InGaAs/GaAs quantum-dot superlattice

    NASA Astrophysics Data System (ADS)

    Zhuang, Q. D.; Li, J. M.; Li, H. X.; Zeng, Y. P.; Pan, L.; Chen, Y. H.; Kong, M. Y.; Lin, L. Y.

    1998-12-01

    Normal-incident infrared absorption in the 8-12-μm-atmospheric spectral window in the InGaAs/GaAs quantum-dot superlattice is observed. Using cross-sectional transmission electron microscopy, we find that the InGaAs quantum dots are perfectly vertically aligned in the growth direction (100). Under the normal incident radiation, a distinct absorption peaked at 9.9 μm is observed. This work indicates the potential of this quantum-dot superlattice structure for use as normal-incident infrared imaging focal arrays application without fabricating grating structures.

  12. ESA's advanced relay and technology mission

    NASA Astrophysics Data System (ADS)

    Lechte, H.; Bird, A. G.; van Holtz, L.; Oppenhauser, G.

    1990-05-01

    The Advanced Relay and Technology Mission is discussed. The objective of the mission is to develop, launch, and operate a single geostationary satellite. The proposed satellite includes advanced communications payloads with data-relay, mobile, and fixed-service applications. The semiconductor laser intersatellite link experiment (Silex), which is aimed at developing an optical communications data-relay system, is described. The Silex configuration is designed for LEO or GEO applications and has a 65 Mbit/s data rate over the optical return link. Consideration is given to the phased-array technology utilized in the S-band data-relay payload; the L-band land mobile payload; diagnostics and propagation packages; and technology experiments for improving the platform.

  13. Electronic transitions and heterogeneity of the bacteriophytochrome Pr absorption band: An angle balanced polarization resolved femtosecond VIS pump–IR probe study

    PubMed Central

    Linke, Martin; Yang, Yang; Zienicke, Benjamin; Hammam, Mostafa A.S.; von Haimberger, Theodore; Zacarias, Angelica; Inomata, Katsuhiko; Lamparter, Tilman; Heyne, Karsten

    2013-01-01

    Photoisomerization of biliverdin (BV) chromophore triggers the photoresponse in native Agp1 bacteriophytochrome. We discuss heterogeneity in phytochrome Pr form to account for the shape of the absorption profile. We investigated different regions of the absorption profile by angle balanced polarization resolved femtosecond VIS pump–IR probe spectroscopy. We studied the Pr form of Agp1 with its natural chromophore and with a sterically locked 18Et-BV (locked Agp1). We followed the dynamics and orientations of the carbonyl stretching vibrations of ring D and ring A in their ground and electronically excited states. Photoisomerization of ring D is reflected by strong signals of the ring D carbonyl vibration. In contrast, orientational data on ring A show no rotation of ring A upon photoexcitation. Orientational data allow excluding a ZZZasa geometry and corroborates a nontwisted ZZZssa geometry of the chromophore. We found no proof for heterogeneity but identified a new, to our knowledge, electronic transition in the absorption profile at 644 nm (S0→S2). Excitation of the S0→S2 transition will introduce a more complex photodynamics compared with S0→S1 transition. Our approach provides fundamental information on disentanglement of absorption profiles, identification of chromophore structures, and determination of molecular groups involved in the photoisomerization process of photoreceptors. PMID:24138851

  14. Rovibrational Intensities of the (00(0)3) <-- (10(0)0) Dyad Absorption Bands of (12)C(16)O(2).

    PubMed

    Kshirsagar; Giver; Chackerian

    2000-02-01

    Absolute line intensities of (12)C(16)O(2) are experimentally measured for the first time for the (00(0)3)(I) <-- (10(0)0)(II) band at 5687.17 cm(-1) and the (00(0)3)(I) <-- (10(0)0)(I) band at 5584.39 cm(-1). The spectra were obtained using a Bomem DA8 Fourier transform spectrometer and a 25-m base-path White cell at NASA-Ames Research Center. The rotationless bandstrengths at a temperature of 296 K and the Herman-Wallis parameters are S(0)(vib) = 6.68(30) x 10(-25) cm(-1)/(molecule/cm(2)); A(1) = 1.4(9) x 10(-4), and A(2) = -1.1(5) x 10(-5) for the (00(0)3)(I) <-- (10(0)0)(II) band and S(0)(vib) = 6.07(22) x 10(-25) cm(-1)/(molecule/cm(2)); A(1) = 5.2(1.5) x 10(-4) and A(2) = -4.0(7) x 10(-5) for the (00(0)3)(I) <-- (10(0)0)(I) band. PMID:10637108

  15. Follow the Mars Express launch from one of ESA's establishments

    NASA Astrophysics Data System (ADS)

    2003-05-01

    Europe’s first mission to the Red Planet will reach its target in December, after a six-month journey. Mars Express will help scientists answer questions about the Martian landscape, atmosphere and the origin of life that remain open, although a wealth of information is already available. Media representatives in Europe can follow the launch and initial orbital operations at ESA/Darmstadt (ESOC) in Germany, which will be acting as the main European press centre, or ESA/Noordwijk (ESTEC) in the Netherlands. ESA/Frascati (ESRIN) in Italy and the Italian Space Agency, ASI, are organising a joint event at the University of Rome. ESA/Villafranca (VILSPA) and the CDTI, the Spanish institution in charge of space issues, are organising a joint event in Spain at the Museo Principe Felipe de la Ciudad de las Artes y las Ciencias in Valencia. At each site ESA specialists will be available for interviews. Media representatives wishing to attend are requested to complete the attached reply form and fax it to the Communication Office at the establishment of their choice. The ESA TV Service will provide live televised coverage of the launch and initial orbital operations with English commentary, between 19:15 and 22:00 CEST. Satellite: Astra 2C at 19 degrees East Reception frequency: 10832 MHz Polarisation: Horizontal Symbol rate: 22 Msymb/s FEC: 5/6 Service ID: 61950 Service name: ESA TXT: none Details of the transmission schedule and satellite details for the various pre-launch Video News Releases can be found on http://television.esa.int. The launch can also be followed live on the internet at www.esa.int/marsexpresslaunch starting at 19:15 hrs. Here you can also find the launch diary, news, press releases, videos, images and more.

  16. ESA's Hipparcos finds rebels with a cause

    NASA Astrophysics Data System (ADS)

    2004-10-01

    hi-res Size hi-res: 20Kb Credits: S. Kerroudj, B. Famaey & A. Jorissen (Université Libre de Bruxelles) Artist's impression of the Milky Way Artist's impression of our galaxy, the Milky Way, an aggregate of thousands of millions of stars. The spiral arms are clearly visible. They are regions of enhanced density of stars and gas. The Sun is located near the edge of one arm, about half-way from the galactic centre. Spiral arms can impart a kick on stars orbiting close to them. These stars are then forced unto streams running inwards or outwards, whereas the bulk of stars in the Milky Way move in circular orbits around the galactic centre. Using data from ESA’s Hipparcos satellite, astronomers have now identified three such streams, reaching into the solar neighbourhood. High-resolution version (TIFF) Low-resolution version (JPG) The Sun and most stars near it follow an orderly, almost circular orbit around the centre of our galaxy, the Milky Way. Using data from ESA's Hipparcos satellite, a team of European astronomers has now discovered several groups of 'rebel' stars that move in peculiar directions, mostly towards the galactic centre or away from it, running like the spokes of a wheel. These rebels account for about 20% of the stars within 1000 light-years of the Sun, itself located about 25 000 light-years away from the centre of the Milky Way. The data show that rebels in the same group have little to do with each other. They have different ages so, according to scientists, they cannot have formed at the same time nor in the same place. Instead, they must have been forced together. "They resemble casual travel companions more than family members," said Dr Benoit Famaey, Université Libre de Bruxelles, Belgium. Famaey and his colleagues believe that the cause forcing the rebel stars together on their unusual trajectory is a 'kick' received from one of the Milky Way's spiral arms. The spiral arms are not solid structures but rather regions of higher density of

  17. ESA to launch six scientific satellites

    NASA Astrophysics Data System (ADS)

    1995-09-01

    ship to Europe's spaceport in Kourou, French Guiana. Since then, all the satellite subsystems and scientific instruments have been thoroughly tested and found to be in order. ISO is now waiting its turn to be mated with the Ariane 44P launcher. The launch campaign will resume in early October for a launch on 3 November. Preparations for flight operations by ESA's space operation centre, ESOC in Darmstadt, Germany and the flight control centre at Villafranca, near Madrid, Spain are also in the final stages. Most of the work in the last two months before a launch involves training and performing simulations to prove flight readiness. The scientific community is eagerly awaiting the preliminary results of ISO's first look into space in November. SOHO SOHO arrived at Kennedy Space Centre on 1 August. It was given a welcome by hurricane ERIN, which forced an immediate transfer to its reserved NASA facility just after its transport plane had safely landed. Spacecraft preparation for launch has started with a thorough check of all the systems and instruments onboard SOHO and will proceed with an end-to-end test with the NASA control station at Goddard Spaceflight Centre. Parallel activities are proceeding in Europe on the final testing and inspection of the four reaction wheels which the spacecraft control system uses to keep all its instruments pointed very precisely at the sun. At the end of its preparation, the spacecraft will be mated to its Atlas IIAS launcher, which is due to lift off in the first week of December. CLUSTER All four Cluster spacecraft, together with all ancillary equipment, have now arrived at Europe's spaceport in Kourou, French Guiana. The spacecraft have been set up for final electrical testing in the Final Assembly Building , a new Ariane 5 facility. Major milestones in the campaign are the start of spacecraft fuelling operations at the beginning of November and the start of integration of the spacecraft with the launch vehicle in mid- December. The

  18. mkESA: enhanced suffix array construction tool.

    PubMed

    Homann, Robert; Fleer, David; Giegerich, Robert; Rehmsmeier, Marc

    2009-04-15

    We introduce the tool mkESA, an open source program for constructing enhanced suffix arrays (ESAs), striving for low memory consumption, yet high practical speed. mkESA is a user-friendly program written in portable C99, based on a parallelized version of the Deep-Shallow suffix array construction algorithm, which is known for its high speed and small memory usage. The tool handles large FASTA files with multiple sequences, and computes suffix arrays and various additional tables, such as the LCP table (longest common prefix) or the inverse suffix array, from given sequence data. PMID:19246510

  19. Matrix-assisted laser desorption and ionization in the O---H and C=O absorption bands of aliphatic and aromatic matrices: dependence on laser wavelength and temporal beam profile

    NASA Astrophysics Data System (ADS)

    Cramer, Rainer; Haglund, Richard F.; Hillenkamp, Franz

    1997-12-01

    A tunable free-electron laser (FEL) was used to initiate infrared (IR) matrix-assisted laser desorption and ionization (MALDI) of small proteins in aliphatic and aromatic matrices. The laser wavelength was scanned from 2.65 to 4.2 [mu]m and from 5.5 to 6.5 [mu]m, covering the absorption bands of the O---H and C=O stretching vibrations found in such commonly used IR matrices as succinic, fumaric and nicotinic acids. The temporal profile of the laser pulse was also varied using a broadband electro-optic switch (Pockels cell) to study the effects of fluence and irradiance. Although there are absorption peaks at 3.3 [mu]m for succinic acid and fumaric acid, and at 4.1 [mu]m for nicotinic acid, the lowest threshold-fluence for IR MALDI in this region was around 2.94 [mu]m for all matrices. Moreover, the threshold-fluence increased with increasing absorption up to a value five times that of the 2.94 [mu]m value. This result raises questions about the relative contributions of the different sample constitutents to the absorption and the role of resonant absorption in IR MALDI. The threshold-fluences are typically one order of magnitude higher than those for ultraviolet (UV) MALDI, while extinction coefficients of the IR matrices are 100-1000 times smaller than for UV matrices. Therefore, the absorbed energies per unit volume at the MALDI threshold are 10-100 times smaller than in UV MALDI. All these facts clearly indicate that a different desorption/ionization process must be operative in IR MALDI. Variations in temporal profile of the FEL pulse also revealed that ion desorption depends on laser irradiance rather than laser fluence, a result which cannot be explained simply by energy loss due to heat conduction. Two possible models for IR desorption are suggested based on these observations.

  20. Status of esa smart-1 mission to the moon

    NASA Astrophysics Data System (ADS)

    Foing, B. H.; Racca, G. R.; Marini, A.; SMART-1 Technology Working Team

    2003-04-01

    SMART-1 is the first in the programme of ESA’s Small Missions for Advanced Research and Technology . Its objective is to demonstrate Solar Electric Primary Propulsion (SEP) for future Cornerstones (such as Bepi-Colombo) and to test new technologies for spacecraft and instruments. The spacecraft has been readied for launch in spring 2003 as an Ariane-5 auxiliary passenger. After a cruise with primary SEP, the SMART-1 mission is to orbit the Moon for a nominal period of six months, with possible extension. The spacecraft will carry out a complete programme of scientific observations during the cruise and in lunar orbit. SMART-1's science payload, with a total mass of some 19 kg, features many innovative instruments and advanced technologies. A miniaturised high-resolution camera (AMIE) for lunar surface imaging, a near-infrared point-spectrometer (SIR) for lunar mineralogy investigation, and a very compact X-ray spectrometer (D-CIXS) with a new type of detector and micro-collimator which will provide fluorescence spectroscopy and imagery of the Moon's surface elemental composition. The payload also includes an experiment (KaTE) aimed at demonstrating deep-space telemetry and telecommand communications in the X and Ka-bands, a radio-science experiment (RSIS), a deep space optical link (Laser-Link Experiment), using the ESA Optical Ground station in Tenerife, and the validation of a system of autonomous navigation SMART-1 lunar science investigations include studies of the chemical (OBAN) based on image processing. SMART-1 lunar science investigations include studies of the chemical composition and evolution of the Moon, of geophysical processes (volcanism, tectonics, cratering, erosion, deposition of ices and volatiles) for comparative planetology, and high resolution studies in preparation for future steps of lunar exploration. The mission could address several topics such as the accretional processes that led to the formation of planets, and the origin of the

  1. Science performance of Gaia, ESA's space-astrometry mission

    NASA Astrophysics Data System (ADS)

    de Bruijne, J. H. J.

    2012-09-01

    Gaia is the next astrometry mission of the European Space Agency (ESA), following up on the success of the Hipparcos mission. With a focal plane containing 106 CCD detectors, Gaia will survey the entire sky and repeatedly observe the brightest 1,000 million objects, down to 20th magnitude, during its 5-year lifetime. Gaia's science data comprises absolute astrometry, broad-band photometry, and low-resolution spectro-photometry. Spectroscopic data with a resolving power of 11,500 will be obtained for the brightest 150 million sources, down to 17th magnitude. The thermo-mechanical stability of the spacecraft, combined with the selection of the L2 Lissajous point of the Sun-Earth/Moon system for operations, allows stellar parallaxes to be measured with standard errors less than 10 micro-arcsecond (μas) for stars brighter than 12th magnitude, 25 μas for stars at 15th magnitude, and 300 μas at magnitude 20. Photometric standard errors are in the milli-magnitude regime. The spectroscopic data allows the measurement of radial velocities with errors of 15 km s-1 at magnitude 17. Gaia's primary science goal is to unravel the kinematical, dynamical, and chemical structure and evolution of the Milky Way. In addition, Gaia's data will touch many other areas of science, e.g., stellar physics, solar-system bodies, fundamental physics, and exo-planets. The Gaia spacecraft is currently in the qualification and production phase. With a launch in 2013, the final catalogue is expected in 2021. The science community in Europe, organised in the Data Processing and Analysis Consortium (DPAC), is responsible for the processing of the data.

  2. High-resolution absorption cross sections of carbon monoxide bands at 295 K between 91.7 and 100.4 nanometers

    NASA Technical Reports Server (NTRS)

    Stark, G.; Yoshino, K.; Smith, Peter L.; Ito, K.; Parkinson, W. H.

    1991-01-01

    Theoretical descriptions of the abundance and excitation of carbon monoxide in interstellar clouds require accurate data on the vacuum-ultraviolet absorption spectrum of the molecule. The 6.65 m spectrometer at the Photon Factory synchrotron light source was used to measure photoabsorption cross sections of CO features between 91.2 and 100.4 nm. These data were recorded at a resolving power of 170,000, more than 20 times greater than that used in previous work.

  3. Intensities and self-broadening coefficients of the strongest water vapour lines in the 2.7 and 6.25 μm absorption bands

    NASA Astrophysics Data System (ADS)

    Ptashnik, Igor V.; McPheat, Robert; Polyansky, Oleg L.; Shine, Keith P.; Smith, Kevin M.

    2016-07-01

    Intensities and self-broadening coefficients are presented for about 460 of the strongest water vapour lines in the spectral regions 1400-1840 cm-1 and 3440-3970 cm-1 at room temperature, obtained from rather unique measurements using a 5-mm-path-length cell. The retrieved spectral line parameters are compared with those in the HITRAN database ver. 2008 and 2012 and with recent ab-initio calculations. Both the retrieved intensities and half-widths are on average in reasonable agreement with those in HITRAN-2012. Maximum systematic differences do not exceed 4% for intensities (1600 cm-1 band) and 7% for self-broadening coefficients (3600 cm-1 band). For many lines however significant disagreements were detected with the HITRAN-2012 data, exceeding the average uncertainty of the retrieval. In addition, water vapour line parameters for 5300 cm-1 (1.9 μm) band reported by us in 2005 were also compared with HITRAN-2012, and show average differences of 4-5% for both intensities and half-widths.

  4. "Cosmic Vision": the new ESA Science Programme

    NASA Astrophysics Data System (ADS)

    2002-05-01

    The outcome of the ESA Council at Ministerial level held in Edinburgh in November 2001 was not as positive as expected for the Agency's Science Programme. It appeared that the money made available would not be sufficient to carry out the Long Term Programme approved by the Science Programme Committee in October 2000, based on financial assumptions approved by the same Committee in Bern in May 1999. The resources granted in Edinburgh taken at their face value meant the cancellation of a mission (e.g. GAIA). At the conclusion of the exercise, following extensive consultations with all its partners, the Executive could propose a revised plan, which not only maintained the missions approved in October 2000, but added the Eddington mission in addition. The new plan, strongly endorsed by the Science Programme Committee on the occasion of its 99th meeting, contains the following missions, listed by production groups: Astrophysics Group 1: XMM-Newton (1999), INTEGRAL (2002). X and Gamma Ray Observatories (studying the 'violent' universe) Group 2: Herschel, exploring the infrared and microwave universe; Planck, to study the cosmic microwave background; Eddington, searching for extra-solar planets and studying the stellar seismology. (The three missions will be launched in the 2007-2008 timeframe.) Group 3: GAIA, the ultimate galaxy mapper (to be launched no later than 2012). Missions will follow in the same group after 2012. Solar System Science: Group 1:Rosetta, a trip to a comet (2003); Mars Express, a Mars orbiter carrying the Beagle2 lander (2003); (Venus Express, a Venus orbiter, would have been in this group.) Group 2: SMART-1, which will demonstrate solar propulsion technology while on its way to the Moon (2003); BepiColombo, a mission to Mercury, Solar Orbiter, a mission to take a closer look at the Sun (missions to be launched in 2011-2012). Fundamental Physics missions: (one group only) STEP (2005) the 'equivalence principle' test, SMART2, a technology

  5. ESA Unveils Its New Comet Chaser.

    NASA Astrophysics Data System (ADS)

    1999-07-01

    The objective is to study one of these primordial objects at close quarters by placing a lander on its surface and chasing, with an orbiter, the comet for millions of kilometres through space. Comets - among the oldest (4.6 billion years!) and last altered objects in the solar system - are regarded as the building blocks from which the planets formed. Thus the Rosetta's discoveries will allow the scientists to learn more about birth and evolution of the planets and about the origin of life on the Earth. The final design of the Rosetta orbiter will be revealed for the first time at the Royal Society in London on 1 July when a 1:4 scale model will be unveiled by ESA's Director of Science, Prof.. Roger Bonnet. (The full size version of the spacecraft is 32 metres across, so large that it would stretch the entire width of a football pitch. Almost 90 of this is accounted for by the giant solar panels which are needed to provide electrical power in the dark depths of the Solar System). "Rosetta is a mission of major scientific importance," said Prof. Bonnet. "It will build on the discoveries made by Giotto and confirm ESA's leading role in the exploration of the Solar System and the Universe as a whole." The timing of this event has been chosen to coincide with the London meeting of the Rosetta Science Working Team and the second Earth flyby of the now non-operational Giotto spacecraft. In addition, the opening of the British Museum's 'Cracking Codes' Exhibition, for which the Rosetta Stone is the centrepiece, is set to take place on 10 July. The Rosetta mission. Rosetta is the third Cornerstone in ESA's 'Horizon 2000' long-term scientific programme. It will be launched by Ariane 5 rocket from Kourou spaceport in French Guiana in January 2003. In order to gain sufficient speed to reach the distant comet, Rosetta will require gravity assists from the Earth (twice) and Mars. After swinging around Mars in May 2005, Rosetta will return to Earth's vicinity in October 2005 and

  6. Operation IceBridge/ESA Collaboration Benefits All

    NASA Video Gallery

    For the second straight year, NASA's Operation IceBridge is collaborating with the European Space Agency's CryoVEx program, flying aircraft low over Arctic sea ice while ESA's CryoSat satellite orb...

  7. mkESA: enhanced suffix array construction tool

    PubMed Central

    Homann, Robert; Fleer, David; Giegerich, Robert; Rehmsmeier, Marc

    2009-01-01

    Summary: We introduce the tool mkESA, an open source program for constructing enhanced suffix arrays (ESAs), striving for low memory consumption, yet high practical speed. mkESA is a user-friendly program written in portable C99, based on a parallelized version of the Deep-Shallow suffix array construction algorithm, which is known for its high speed and small memory usage. The tool handles large FASTA files with multiple sequences, and computes suffix arrays and various additional tables, such as the LCP table (longest common prefix) or the inverse suffix array, from given sequence data. Availability: The source code of mkESA is freely available under the terms of the GNU General Public License (GPL) version 2 at http://bibiserv.techfak.uni-bielefeld.de/mkesa/. Contact: rhomann@techfak.uni-bielefeld.de PMID:19246510

  8. Sharing ESA's knowledge and experience - the Erasmus Experiment Archive

    NASA Astrophysics Data System (ADS)

    Isakeit, Dieter; Sabbatini, Massimo; Carey, William

    2004-11-01

    The Erasmus Experiment Archive is an electronic database, that collects all experiments performed to date in the faciliteis that fall under the responsibility of the ESA (human spaceflight, microgravity, exploration).

  9. Cirrus cloud optical and microphysical property retrievals from eMAS during SEAC4RS using bi-spectral reflectance measurements within the 1.88 µm water vapor absorption band

    NASA Astrophysics Data System (ADS)

    Meyer, Kerry; Platnick, Steven; Arnold, G. Thomas; Holz, Robert E.; Veglio, Paolo; Yorks, John; Wang, Chenxi

    2016-04-01

    Previous bi-spectral imager retrievals of cloud optical thickness (COT) and effective particle radius (CER) based on the Nakajima and King (1990) approach, such as those of the operational MODIS cloud optical property retrieval product (MOD06), have typically paired a non-absorbing visible or near-infrared wavelength, sensitive to COT, with an absorbing shortwave or mid-wave infrared wavelength sensitive to CER. However, in practice it is only necessary to select two spectral channels that exhibit a strong contrast in cloud particle absorption. Here it is shown, using eMAS observations obtained during NASA's SEAC4RS field campaign, that selecting two absorbing wavelength channels within the broader 1.88 µm water vapor absorption band, namely the 1.83 and 1.93 µm channels that have sufficient differences in ice crystal single scattering albedo, can yield COT and CER retrievals for thin to moderately thick single-layer cirrus that are reasonably consistent with other solar and IR imager-based and lidar-based retrievals. A distinct advantage of this channel selection for cirrus cloud retrievals is that the below-cloud water vapor absorption minimizes the surface contribution to measured cloudy top-of-atmosphere reflectance, in particular compared to the solar window channels used in heritage retrievals such as MOD06. This reduces retrieval uncertainty resulting from errors in the surface reflectance assumption and reduces the frequency of retrieval failures for thin cirrus clouds.

  10. The ESA Planetary Science Archive User Group (PSA-UG)

    NASA Astrophysics Data System (ADS)

    Pio Rossi, Angelo; Cecconi, Baptiste; Fraenz, Markus; Hagermann, Axel; Heather, David; Rosenblatt, Pascal; Svedhem, Hakan; Widemann, Thomas

    2014-05-01

    ESA has established a Planetary Science Archive User Group (PSA-UG), with the task of offering independent advice to ESA's Planetary Science Archive (e.g. Heather et al., 2013). The PSA-UG is an official and independent body that continuously evaluates services and tools provided by the PSA to the community of planetary data scientific users. The group has been tasked with the following top level objectives: a) Advise ESA on future development of the PSA. b) Act as a focus for the interests of the scientific community. c) Act as an advocate for the PSA. d) Monitor the PSA activities. Based on this, the PSA-UG will report through the official ESA channels. Disciplines and subjects represented by PSA-UG members include: Remote Sensing of both Atmosphere and Solid Surfaces, Magnetospheres, Plasmas, Radio Science and Auxilliary data. The composition of the group covers ESA missions populating the PSA both now and in the near future. The first members of the PSA-UG were selected in 2013 and will serve for 3 years, until 2016. The PSA-UG will address the community through workshops, conferences and the internet. Written recommendations will be made to the PSA coordinator, and an annual report on PSA and the PSA-UG activities will be sent to the Solar System Exploration Working Group (SSEWG). Any member of the community and planetary data user can get in touch with individual members of the PSA-UG or with the group as a whole via the contacts provided on the official PSA-UG web-page: http://archives.esac.esa.int/psa/psa-ug. The PSA is accessible via: http://archives.esac.esa.int/psa References: Heather, D., Barthelemy, M., Manaud, N., Martinez, S., Szumlas, M., Vazquez, J. L., Osuna, P. and the PSA Development Team (2013) ESA's Planetary Science Archive: Status, Activities and Plans. EuroPlanet Sci. Congr. #EPSC2013-626

  11. ESA Experiments with the European Modular Cultivation System (EMCS)

    NASA Astrophysics Data System (ADS)

    Brillouet, Claude; Briganti, Luca; Schwarzwalder, Achim

    2008-06-01

    The European Modular Cultivation System (EMCS) is an ESA developed facility dedicated to gravitational biology and especially to plant research. However, experiments using small animals, like insects and small invertebrates are also possible. EMCS is onboard the International Space Station (ISS) since July 2006 and four experiments, including two from ESA, have been already performed. Several others are in their final development phase and shall be flown within the next following years.

  12. Modeling of collision-induced infrared absorption spectra of H2-H2 pairs in the fundamental band at temperatures from 20 to 300 K. [Planetary atmospheres

    SciTech Connect

    Borysow, A. )

    1991-08-01

    The 20-300 K free-free rotovibrational collision-induced absorption (RV CIA) spectra of H2-H2 pairs are presently obtained by a numerical method which, in addition to closely matching known CIA spectra of H2-H2, can reproduce the results of the quantum-mechanical computations to within a few percent. Since the spectral lineshape parameters are derivable by these means from the lowest three quantum-mechanical spectral moments, these outer-planet atmosphere-pertinent model spectra may be computed on even small computers. 35 refs.

  13. Evaluation of SCIAMACHY Oxygen A band cloud heights using Cloudnet measurements

    NASA Astrophysics Data System (ADS)

    Wang, P.; Stammes, P.

    2014-05-01

    Two SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY) O2 A band cloud height products are evaluated using ground-based radar/lidar measurements between January 2003 and December 2011. The products are the ESA (European Space Agency) Level 2 (L2) version 5.02 cloud top height and the FRESCO (Fast Retrieval Scheme for Clouds from the Oxygen A band) version 6 cloud height. The radar/lidar profiles are obtained at the Cloudnet sites of Cabauw and Lindenberg, and are averaged for 1 h centered at the SCIAMACHY overpass time. In total we have 217 cases of single-layer clouds and 204 cases of multilayer clouds. We find that the ESA L2 cloud top height has a better agreement with the Cloudnet cloud top height than the Cloudnet cloud middle height. The ESA L2 cloud top height is on average 0.4 km higher than the Cloudnet cloud top height, with a standard deviation of 3.1 km. The FRESCO cloud height is closer to the Cloudnet cloud middle height than the Cloudnet cloud top height. The mean difference between the FRESCO cloud height and the Cloudnet cloud middle height is -0.1 km with a standard deviation of 1.9 km. The ESA L2 cloud top height is higher than the FRESCO cloud height. The differences between the SCIAMACHY cloud (top) height and the Cloudnet cloud top height are linked to cloud optical thickness. The SCIAMACHY cloud height products are further compared to the Cloudnet cloud top height and the Cloudnet cloud middle height in 1 km bins. For single-layer clouds, the difference between the ESA L2 cloud top height and the Cloudnet cloud top height is less than 1 km for each cloud bin at 3-7 km. The difference between the FRESCO cloud height and the Cloudnet cloud middle height is less than 1 km for each cloud bin at 0-6 km. The results are similar for multilayer clouds, but the percentage of cases having a bias within 1 km is smaller than for single-layer clouds. We may conclude that the FRESCO cloud height is accurate for low and middle

  14. Coloration and oxygen vacancies in wide band gap oxide semiconductors: Absorption at metallic nanoparticles induced by vacancy clustering—A case study on indium oxide

    SciTech Connect

    Albrecht, M. Schewski, R.; Irmscher, K.; Galazka, Z.; Markurt, T.; Naumann, M.; Schulz, T.; Uecker, R.; Fornari, R.; Meuret, S.; Kociak, M.

    2014-02-07

    In this paper, we show by optical and electron microscopy based investigations that vacancies in oxides may cluster and form metallic nanoparticles that induce coloration by extinction of visible light. Optical extinction in this case is caused by generation of localized surface plasmon resonances at metallic particles embedded in the dielectric matrix. Based on Mie's approach, we are able to fit the absorption due to indium nanoparticles in In{sub 2}O{sub 3} to our absorption measurements. The experimentally found particle distribution is in excellent agreement with the one obtained from fitting by Mie theory. Indium particles are formed by precipitation of oxygen vacancies. From basic thermodynamic consideration and assuming theoretically calculated activation energies for vacancy formation and migration, we find that the majority of oxygen vacancies form just below the melting point. Since they are ionized at this temperature they are Coulomb repulsive. Upon cooling, a high supersaturation of oxygen vacancies forms in the crystal that precipitates once the Fermi level crosses the transition energy level from the charged to the neutral charge state. From our considerations we find that the ionization energy of the oxygen vacancy must be higher than 200 meV.

  15. ESA unveils its big XMM spacecraft

    NASA Astrophysics Data System (ADS)

    1998-02-01

    have to imagine the big tube of XMM filled with focused X-rays en route to the detectors », says Robert Lainé, ESA's project manager for XMM. « That is the whole purpose of the mission, and our chief preoccupation has been with the three multi-mirror modules that accomplish it. Critics thought we were too ambitious, trying to nest 58 precisely formed mirrors together in each module. No one had ever attempted such a feat before. It was not easy, but thanks to excellent innovative work by European industry, XMM's telescopes are even better than we hoped ». X-rays are focused by glancing them off a carefully shaped mirror, like a bucket without a bottom. In a single-mirror telescope, most of the incoming X-rays miss the mirror. To catch more of them, designers nest multiple mirrors inside one another. Before XMM, astronomers had to choose between many mirrors with relatively poor focusing, or a very few mirrors with a sharp focus. With 58 precision-made mirrors in each of its three X-ray telescopes, XMM combines enormous gathering power with accurate focusing. Carl Zeiss in Germany made shaped and polished mandrels (moulds) for mirrors of 58 different diameters, up to 70 cm for the widest. Media Lario in Italy made the mirrors by electrodeposition of nickel on the mandrels, coated their inner surfaces with gold, and carefully assembled them in their nested configuration, in a framework fabricated by APCO in Switzerland. The performance of each XMM mirror module has been verified in special facilities of the Centre Spatial de Liège in Belgium and the Max-Planck Institut für extraterrestriche Physik in Germany. The first flight model conformed with the specification, and the second and third were even better. Some facts about XMM The total surface area of the extremely thin mirror that gathers X-rays in XMM's three multi-mirror telescopes (taken together) is larger than 200 m2. Two of the three X-ray telescopes are fitted with reflection grating spectrometers for the

  16. Edwardsiella tarda EsaE (Orf19 protein) is required for the secretion of type III substrates, and pathogenesis in fish.

    PubMed

    Zhou, Ying; Liu, Lu Yi; He, Tian Tian; Laghari, Zubair Ahmed; Nie, Pin; Gao, Qian; Xie, Hai Xia

    2016-07-15

    Type III secretion system (T3SS) is a large macromolecular assembly found on the surface of many pathogenic Gram-negative bacteria. Edwardsiella tarda is an important Gram-negative pathogen that employs T3SS to deliver effectors into host cells to facilitate its survival and replication. EseB, EseC, and EseD, when secreted, form a translocon complex EseBCD on host membranes through which effectors are translocated. The orf19 gene (esaE) of E. tarda is located upstream of esaK, and downstream of esaJ, esaI, esaH and esaG in the T3SS gene cluster. When its domains were searched using Delta-Blast, the EsaE protein was found to belong to the T3SS YscJ/PrgK family. In the present study, it is found that EsaE is not secreted into culture supernatant, and the deletion of esaE abolished the secretion of T3SS translocon proteins EseBCD and T3SS effector EseG. Increased steady-state protein level of EseC and EseD was detected in bacterial pellet of ΔesaE strain although a reduced level was observed for the eseC and eseD transcription. EsaE was found to localize on membrane but not in the cytoplasm of E. tarda by fractionation. In blue gourami fish infection model, 87.88% of blue gourami infected with ΔesaE strain survived whereas only 3.03% survived when infected with wild-type strain. Taken together, our study demonstrated that EsaE is probably an apparatus protein of T3SS, which contributes to the pathogenesis of E. tarda in fish. PMID:27283851

  17. Security Concepts and Implementation on the ESA ISS Exploitation Program Ground Infrastructure for the ESA Human Space Projects

    NASA Astrophysics Data System (ADS)

    van Leeuwen, W.

    2007-08-01

    This paper addresses a number of security techniques utilized as part of the implementation of the ESA ISS Exploitation Program ground infrastructure in support of the operations and utilization of the ESA element level contributions to the International Space Station (ISS). Those Flight Elements COLUMBUS (a laboratory with payloads accommodation) and ATV (Autonomous Transfer Vehicle) are planned to be launched end of the year 2007.

  18. Resonance-Enhanced Raman Scattering of Ring-Involved Vibrational Modes in the (1)B(2u) Absorption Band of Benzene, Including the Kekule Vibrational Modes ν(9) and ν(10).

    PubMed

    Willitsford, Adam H; Chadwick, C Todd; Kurtz, Stewart; Philbrick, C Russell; Hallen, Hans

    2016-02-01

    Resonance Raman spectroscopy provides much stronger Raman signal levels than its off-resonant counterpart and adds selectivity by excitation tuning. Raman preresonance of benzene has been well studied. On-resonance studies, especially at phonon-allowed absorptions, have received less attention. In this case, we observe resonance of many of the vibration modes associated motion of the carbons in the ring while tuning over the (1)B2u absorption, including the related ν9 (CC stretch Herzberg notation, ν14 Wilson notation) and ν10 (CH-parallel bend Herzberg notation, ν15 Wilson notation) vibrational modes along with the ν2 (CC-stretch or ring-breathing Herzberg notation, ν1 Wilson notation) mode and multiples of the ν18 (CCC-parallel bend Herzberg notation, ν6 Wilson notation) vibrational mode. The ring-breathing mode is found to mix with the b2u modes creating higher frequency composites. Through the use of an optical parametric oscillator (OPO) to tune through the (1)B2u absorption band of liquid benzene, a stiffening (increase in energy) of the vibrational modes is observed as the excitation wavelength nears the (1)B2u absorption peak of the isolated molecule (vapor) phase. The strongest resonance amplitude observed is in the 2 × ν18 (e2g) mode, with nearly twice the intensity of the ring-breathing mode, ν2. Several overtones and combination modes, especially with ν2 (a1g), are also observed to resonate. Raman resonances on phonon-allowed excitations are narrow and permit the measurement of vibrations not Raman-active in the ground state. PMID:26731431

  19. The ESA Planetary Science Archive User Group (PSA-UG)

    NASA Astrophysics Data System (ADS)

    Rossi, A. P.; Cecconi, B.; Fraenz, M.; Hagermann, A.; Heather, D.; Rosenblatt, P.; Svedhem, H.; Widemann, T.

    2014-04-01

    ESA has established a Planetary Science Archive User Group (PSA-UG), with the task of offering independent advice to ESA's Planetary Science Archive (e.g. Heather et al., 2013). The PSA-UG is an official and independent body that continuously evaluates services and tools provided by the PSA to the community of planetary data scientific users. The group has been tasked with the following top level objectives: a) Advise ESA on future development of the PSA. b) Act as a focus for the interests of the scientific community. c) Act as an advocate for the PSA. d) Monitor the PSA activities. Based on this, the PSA-UG will report through the official ESA channels. Disciplines and subjects represented by PSA-UG members include: Remote Sensing of both Atmosphere and Solid Surfaces, Magnetospheres, Plasmas, Radio Science and Auxilliary data. The composition of the group covers ESA missions populating the PSA both now and in the near future. The first members of the PSA-UG were selected in 2013 and will serve for 3 years, until 2016. The PSA-UG will address the community through workshops, conferences and the internet. Written recommendations will be made to the PSA coordinator, and an annual report on PSA and the PSA-UG activities will be sent to the Solar System Exploration Working Group (SSEWG). Any member of the community and planetary data user can get in touch with individual members of the PSA-UG or with the group as a whole via the contacts provided on the official PSA-UG web-page: http://archives.esac.esa.int/psa/psa-ug The PSA is accessible via: http://archives.esac.esa.int/psa

  20. Polar solvent structural parameters from protonation equilibria of aliphatic and alicyclic diamines and from absorption bands of mixed-valence transition-metal complexes

    NASA Astrophysics Data System (ADS)

    Kornyshev, A. A.; Ulstrup, J.

    1986-04-01

    We have applied non-local electrostatic theory in combination with a simple solute model to obtain solvent structural properties in terms of the short-range dielectric constant, ˜ge, and the correlation length for the solvent polarization fluctuations, A. These parameters are fitted to experimental data for the free energy of interaction between protonated amino groups in dibasic amines and for intervalence band maxima of binuclear ruthenium complexes with bridge groups of varying length. The results show that non-local screening in the outer solvent, ˜ge in the range 3.5-4 for water, and A ≈ 2-3 Å and 4 Å for acetonitrile and water, respectively, provide good fits to the data, implying the significance of solvent structural effects for these phenomena.

  1. Packet utilisation definitions for the ESA XMM mission

    NASA Astrophysics Data System (ADS)

    Nye, H. R.

    1994-11-01

    XMM, ESA's X-Ray Multi-Mirror satellite, due for launch at the end of 1999 will be the first ESA scientific spacecraft to implement the ESA packet telecommand and telemetry standards and will be the first ESOC-controlled science mission to take advantage of the new flight control system infrastructure development (based on object-oriented design and distributed-system architecture) due for deployment in 1995. The implementation of the packet standards is well defined at packet transport level. However, the standard relevant to the application level (the ESA Packet Utilization Standard) covers a wide range of on-board 'services' applicable in varying degrees to the needs of XMM. In defining which parts of the ESA PUS to implement, the XMM project first considered the mission objectives and the derived operations concept and went on to identify a minimum set of packet definitions compatible with these aspects. This paper sets the scene as above and then describes the services needed for XMM and the telecommand and telemetry packet types necessary to support each service.

  2. Packet utilisation definitions for the ESA XMM mission

    NASA Technical Reports Server (NTRS)

    Nye, H. R.

    1994-01-01

    XMM, ESA's X-Ray Multi-Mirror satellite, due for launch at the end of 1999 will be the first ESA scientific spacecraft to implement the ESA packet telecommand and telemetry standards and will be the first ESOC-controlled science mission to take advantage of the new flight control system infrastructure development (based on object-oriented design and distributed-system architecture) due for deployment in 1995. The implementation of the packet standards is well defined at packet transport level. However, the standard relevant to the application level (the ESA Packet Utilization Standard) covers a wide range of on-board 'services' applicable in varying degrees to the needs of XMM. In defining which parts of the ESA PUS to implement, the XMM project first considered the mission objectives and the derived operations concept and went on to identify a minimum set of packet definitions compatible with these aspects. This paper sets the scene as above and then describes the services needed for XMM and the telecommand and telemetry packet types necessary to support each service.

  3. Aerosol Climate Time Series in ESA Aerosol_cci

    NASA Astrophysics Data System (ADS)

    Popp, Thomas; de Leeuw, Gerrit; Pinnock, Simon

    2016-04-01

    Within the ESA Climate Change Initiative (CCI) Aerosol_cci (2010 - 2017) conducts intensive work to improve algorithms for the retrieval of aerosol information from European sensors. Meanwhile, full mission time series of 2 GCOS-required aerosol parameters are completely validated and released: Aerosol Optical Depth (AOD) from dual view ATSR-2 / AATSR radiometers (3 algorithms, 1995 - 2012), and stratospheric extinction profiles from star occultation GOMOS spectrometer (2002 - 2012). Additionally, a 35-year multi-sensor time series of the qualitative Absorbing Aerosol Index (AAI) together with sensitivity information and an AAI model simulator is available. Complementary aerosol properties requested by GCOS are in a "round robin" phase, where various algorithms are inter-compared: fine mode AOD, mineral dust AOD (from the thermal IASI spectrometer, but also from ATSR instruments and the POLDER sensor), absorption information and aerosol layer height. As a quasi-reference for validation in few selected regions with sparse ground-based observations the multi-pixel GRASP algorithm for the POLDER instrument is used. Validation of first dataset versions (vs. AERONET, MAN) and inter-comparison to other satellite datasets (MODIS, MISR, SeaWIFS) proved the high quality of the available datasets comparable to other satellite retrievals and revealed needs for algorithm improvement (for example for higher AOD values) which were taken into account for a reprocessing. The datasets contain pixel level uncertainty estimates which were also validated and improved in the reprocessing. For the three ATSR algorithms the use of an ensemble method was tested. The paper will summarize and discuss the status of dataset reprocessing and validation. The focus will be on the ATSR, GOMOS and IASI datasets. Pixel level uncertainties validation will be summarized and discussed including unknown components and their potential usefulness and limitations. Opportunities for time series extension

  4. H(2)O--N(2) collision-induced absorption band intensity in the region of the N(2) fundamental: ab initio investigation of its temperature dependence and comparison with laboratory data.

    PubMed

    Baranov, Yu I; Buryak, I A; Lokshtanov, S E; Lukyanchenko, V A; Vigasin, A A

    2012-06-13

    The present paper aims at ab initio and laboratory evaluation of the N(2) collision-induced absorption band intensity arising from interactions between N(2) and H(2)O molecules at wavelengths of around 4 μm. Quantum chemical calculations were performed in the space of five intermolecular coordinates and varying N--N bond length using Møller-Plesset perturbation and CCSD(T) methods with extrapolation of the electronic energy to the complete basis set. This made it possible to construct the intermolecular potential energy surface and to define the surface of the N--N dipole derivative with respect to internal coordinate. The intensity of the nitrogen fundamental was then calculated as a function of temperature using classical integration. Experimental spectra were recorded with a BOMEM DA3-002 FTIR spectrometer and 2 m base-length multipass White cell. Measurements were conducted at temperatures of 326, 339, 352 and 363 K. The retrieved water-nitrogen continuum significantly deviates from the MT_CKD model because the relatively strong nitrogen absorption induced by H(2)O was not included in this model. Substantial uncertainties in the measurements of the H(2)O-N(2) continuum meant that quantification of any temperature dependence was not possible. The comparison of the integrated N(2) fundamental band intensity with our theoretical estimates shows reasonably good agreement. Theory indicates that the intensity as a function of temperature has a minimum at approximately 500 K. PMID:22547239

  5. Effect of Substitution of Mn, Cu, and Zr on the Structural, Magnetic, and Ku-Band Microwave-Absorption Properties of Strontium Hexaferrite Nanoparticles

    NASA Astrophysics Data System (ADS)

    Rostami, Mohammad; Moradi, Mahmood; Alam, Reza Shams; Mardani, Reza

    2016-08-01

    The ferrites with the compositions of SrMn x Cu x Zr2 x Fe(12-4 x)O19 ( x = 0.0, 0.2, 0.3, 0.4, and 0.5) are synthesized by the coprecipitation method. The formation of M-type hexaferrite is confirmed by x-ray diffraction (XRD) and Fourier transform infrared (FTIR) analyses. The morphology of the samples is shown by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) microscopy. Vibrating sample magnetometer (VSM) analysis has been used for the investigation of the magnetic properties, and the reason for the changes in the magnetic properties as a result of doping, are expressed. The values of coercivity decrease by increasing the amount of substitution, which could be related to the modification of anisotropy form the c-axis toward the c-plane. Finally, we have used vector network analysis to investigate the microwave absorption properties. We find that the samples with the composition of SrMn0.4Cu0.4Zr0.8Fe10.4O19 have the largest reflection loss and the widest bandwidth among these samples.

  6. Enhanced Microwave Absorption of SiO2-Coated Fe0.65Co0.35 Flakes at a Wide Frequency Band (1-18 GHz)

    NASA Astrophysics Data System (ADS)

    Luo, Hui; Gong, Rongzhou; Wang, Xian; Song, Kai; Chen, Yajie; Harris, Vincent G.

    2016-07-01

    Fe0.65Co0.35 (Fe-35Co) flakes were coated with SiO2 by the Stober process. The complex permittivity and permeability of both Fe-35Co and Fe-35Co/SiO2 composites were investigated over the frequency range of 1-18 GHz. Two dielectric resonance peaks were found in the Fe-35Co/SiO2 composite. Magnetic loss was verified to arise predominately from the natural resonance. Of particular importance is the natural resonance frequency increases with the SiO2 cladding. The experiments indicated that a reflection loss (RL) less than -20 dB for the Fe-35Co/SiO2 composites can be measured over the frequency range of 5.16-10.6 GHz with an absorbing thickness of 2-3.5 mm. Furthermore, an optimal RL of -60.23 dB was observed at 6.27 GHz with a thickness of 2.93 mm. The results provide a valuable path towards realizing microwave absorption over a wide frequency range.

  7. Enhanced Microwave Absorption of SiO2-Coated Fe0.65Co0.35 Flakes at a Wide Frequency Band (1-18 GHz)

    NASA Astrophysics Data System (ADS)

    Luo, Hui; Gong, Rongzhou; Wang, Xian; Song, Kai; Chen, Yajie; Harris, Vincent G.

    2016-05-01

    Fe0.65Co0.35 (Fe-35Co) flakes were coated with SiO2 by the Stober process. The complex permittivity and permeability of both Fe-35Co and Fe-35Co/SiO2 composites were investigated over the frequency range of 1-18 GHz. Two dielectric resonance peaks were found in the Fe-35Co/SiO2 composite. Magnetic loss was verified to arise predominately from the natural resonance. Of particular importance is the natural resonance frequency increases with the SiO2 cladding. The experiments indicated that a reflection loss (RL) less than -20 dB for the Fe-35Co/SiO2 composites can be measured over the frequency range of 5.16-10.6 GHz with an absorbing thickness of 2-3.5 mm. Furthermore, an optimal RL of -60.23 dB was observed at 6.27 GHz with a thickness of 2.93 mm. The results provide a valuable path towards realizing microwave absorption over a wide frequency range.

  8. Low-temperature high-resolution absorption spectrum of 14NH3 in the ν1+ν3 band region (1.51 μm)

    NASA Astrophysics Data System (ADS)

    Földes, T.; Golebiowski, D.; Herman, M.; Softley, T. P.; Di Lonardo, G.; Fusina, L.

    2014-09-01

    Jet-cooled spectra of 14NH3 and 15NH3 in natural abundance were recorded using cavity ring-down (CRDS, 6584-6670 cm-1) and cavity enhanced absorption (CEAS, 6530-6700 cm-1) spectroscopy. Line broadening effects in the CRDS spectrum allowed lines with J″-values between 0 and 3 to be identified. Intensity ratios in 14NH3 between the jet-cooled CRDS and literature room-temperature data from Sung et al. (J. Quant. Spectrosc. Radiat. Transfer, 113 (2012), 1066) further assisted the line assignments. Ground state combination differences were extensively used to support the assignments, providing reliable values for J, K and inversion symmetry of the ground state vibrational levels. CEAS data helped in this respect for the lowest J lines, some of which are saturated in the CRDS spectrum. Further information on a/s doublets arose from the observed spectral structures. Thirty-two transitions of 14NH3 were assigned in this way and a limited but significant number (19) of changes in the assignments results, compared to Sung et al. or to Cacciani et al. (J. Quant. Spectrosc. Radiat. Transfer, 113 (2012), 1084). Sixteen known and 25 new low-J transitions were identified for 15NH3 in the CRDS spectrum but the much scarcer literature information did not allow for any more refined assignment. The present line position measurements improve on literature values published for 15NH3 and on some line positions for 14NH3.

  9. A vista of new knowledge from ESA's Hipparcos astronomy mission

    NASA Astrophysics Data System (ADS)

    1997-05-01

    Hipparcos is a milestone in the history of astronomy. In 1985 the American physicist Freeman J. Dyson hailed Hipparcos as the first major new development in space science to come from outside the United States. The spacecraft operated in orbit 1989-93, measuring the angles between stars in the sky. Over a further three years, computing teams across Europe generated a consistent, high-precision plot of 118,000 stars in the Hipparcos Catalogue and somewhat less accurate (but still unprecedented) data on a million stars in the Tycho Catalogue. The distances, motions, pairings and variability of stars are now known far more accurately than ever before. Hipparcos will make an impact on every branch of astronomy, from the Solar System to the history of the Universe, and especially on theories of stars and their evolution. For almost a year, astronomers most closely associated with the mission have had an early view of the completed catalogues and in Venice they will summarize their initial results. The Hipparcos data will be published in June, as an extraordinary contribution from Europe to astronomy all around the world. The success of Hipparcos has created problems for the organizers of Venice symposium. Altogether 190 scientific papers were offered for presentation by various groups of astronomers. With three mornings and three afternoons available for the main scientific sessions, 67 oral presentations are accommodated, by restricting speakers to 10-15 minutes each. For the rest, there will a generous display of results in the form of posters. Thus Hipparcos will be celebrated by a vista of new knowledge. The stars are looking younger Already Hipparcos seems to cure a headache concerning the ages of stars. As recently as last year, astronomers were perplexed by a contradiction between their estimates of the age of the Universe, and stars that seemed to be older. An early Hipparcos result announced in February 1997 (ESA Information Note 04/97) concerned the winking

  10. Singlet molecular oxygen ( sup 1. Delta. sub g O sub 2 ) formation upon irradiation of an oxygen ( sup 3. Sigma. sub g sup minus O sub 2 )-organic molecule charge-transfer absorption band

    SciTech Connect

    Scurlock, R.D.; Ogilby, P.R. )

    1989-07-13

    Singlet molecular oxygen ({sup 1}{Delta}{sub g}O{sub 2}) phosphorescence ({sup 3}{Sigma}{sub g}{sup {minus}}O{sub 2} {l arrow} {sup 1}{Delta}{sub g}O{sub 2}: 1270 nm) has been observed in a time-resolved experiment subsequent to pulsed UV laser irradiation of the oxygen ({sup 3}{Sigma}{sub g}{sup {minus}}O{sub 2})-organic molecule charge-transfer bands of liquid aromatic hydrocarbons (mesitylene, p-xylene, o-xylene, toluene, benzene), ethers (tetrahydrofuran, 1,4-dioxane, glyme, diglyme, triglyme), alcohols (methanol, propanol), and aliphatic hydrocarbons (cyclohexane, cyclooctane, decahydronaphthalene). Although {sup 1}{Delta}{sub g}O{sub 2} could originate from a variety of different processes in these oxygenated solvent systems, we have used the results of several independent experiments to indicate that an oxygen-solvent charge-transfer (CT) state is the {sup 1}{Delta}{sub g}O{sub 2} precursor. Other transient species have also been observed in time-resolved absorption experiments subsequent to pulsed UV irradiation of the oxygen-solvent CT bands. Some of these molecular transients, or species derived from these intermediates, may be responsible for an observed increase in the rate of {sup 1}{Delta}{sub g}O{sub 2} decay under certain conditions.

  11. ANOMALOUS DIFFUSE INTERSTELLAR BANDS IN THE SPECTRUM OF HERSCHEL 36. I. OBSERVATIONS OF ROTATIONALLY EXCITED CH AND CH{sup +} ABSORPTION AND STRONG, EXTENDED REDWARD WINGS ON SEVERAL DIBs

    SciTech Connect

    Dahlstrom, Julie; York, Donald G.; Welty, Daniel E.; Oka, Takeshi; Johnson, Sean; Jiang Zihao; Sherman, Reid; Hobbs, L. M.; Friedman, Scott D.; Sonnentrucker, Paule; Rachford, Brian L.; Snow, Theodore P.

    2013-08-10

    Anomalously broad diffuse interstellar bands (DIBs) at 5780.5, 5797.1, 6196.0, and 6613.6 A are found in absorption along the line of sight to Herschel 36, the star illuminating the bright Hourglass region of the H II region Messier 8. Interstellar absorption from excited CH{sup +} in the J = 1 level and from excited CH in the J = 3/2 level is also seen. To our knowledge, neither those excited molecular lines nor such strongly extended DIBs have previously been seen in absorption from interstellar gas. These unusual features appear to arise in a small region near Herschel 36 which contains most of the neutral interstellar material in the sight line. The CH{sup +} and CH in that region are radiatively excited by strong far-IR radiation from the adjacent infrared source Her 36 SE. Similarly, the broadening of the DIBs toward Herschel 36 may be due to radiative pumping of closely spaced high-J rotational levels of relatively small, polar carrier molecules. If this picture of excited rotational states for the DIB carriers is correct and applicable to most DIBs, the 2.7 K cosmic microwave background may set the minimum widths (about 0.35 A) of known DIBs, with molecular processes and/or local radiation fields producing the larger widths found for the broader DIBs. Despite the intense local UV radiation field within the cluster NGC 6530, no previously undetected DIBs stronger than 10 mA in equivalent width are found in the optical spectrum of Herschel 36, suggesting that neither dissociation nor ionization of the carriers of the known DIBs by this intense field creates new carriers with easily detectable DIB-like features. Possibly related profile anomalies for several other DIBs are noted.

  12. ESA's Earth Observation Programmes in the Changing Anthropocene

    NASA Astrophysics Data System (ADS)

    Liebig, Volker

    2016-07-01

    The intervention will present ESA's Earth Observation programmes and their relevance to studying the anthropocene. ESA's Earth observation missions are mainly grouped into three categories: The Sentinel satellites in the context of the European Copernicus Programme, the scientific Earth Explorers and the meteorological missions. Developments, applications and scientific results for the different mission types will be addressed, along with overall trends and strategies. The Earth Explorers, who form the science and research element of ESA's Living Planet Programme, focus on the atmosphere, biosphere, hydrosphere, cryosphere and Earth's interior. The Earth Explorers also aim at learning more about the interactions between these components and the impact that human activity is having on natural Earth processes. The Sentinel missions provide accurate, timely, long term and uninterrupted data to provide key information services, improving the way the environment is managed, and helping to mitigate the effects of climate change. The operational Sentinel satellites can also be exploited for scientific studies of the anthropocene. In the anthropocene human activities affect the whole planet and space is a very efficient means to measure their impact, but for relevant endeavours to be successful they can only be carried out in international cooperation. ESA maintains long-standing partnerships with other space agencies and institutions worldwide. In running its Earth observation programmes, ESA responds to societal needs and challenges and to requirements resulting from political priorities set by decision makers. Activities related to Climate Change are a prime example. Within ESA's Climate Change Initiative, 13 Essential Climate Variables are constantly monitored to create a long-term record of key geophysical parameters.

  13. ESA is now a major player in global space science

    NASA Astrophysics Data System (ADS)

    1997-07-01

    * Results from the star-fixing satellite Hipparcos, released this summer to the world's astronomers, give the positions and motions of 118,000 stars a hundred times more accurately than ever before. * Every day the Infrared Space Observatory, ISO, examines 45 cosmic objects on average at many different wavelengths never observable before, giving fresh insights into cosmic history and chemistry. * Invaluable new knowledge of the Sun comes from SOHO, the Solar and Heliospheric Observatory, which is the first spacecraft able to observe the Sun's deep interior as well as its stormy surface and atmosphere. Besides these missions making present headlines, several other spacecraft are helping to fulfil ESA's scientific objectives. * 2 - * The launch in October 1997 of ESA's probe Huygens, aboard the Cassini spacecraft bound for Saturn, foreshadows a breakthrough in planetary science in 2004. That is when Huygens will carry its scientific instruments into the unique and puzzling atmosphere of Saturn's moon Titan. * Ulysses, also built in Europe, is exploring hitherto unknown regions of space, after making the first-ever visit to the Sun's polar regions in 1994-95. It will return to the Sun in 2000-2001, to observe the effects of the climax of solar activity due at that time. * The Cluster 2 mission, announced in April 1997 and to be launched in 2000, will explore the Earth's space environment far more throughly than ever before. ESA's decision to replace the four Cluster satellites lost in a launch accident in 1996 ensures that Europe will continue as the leader in solar-terrestrial research in space. * An example of the three unique 58-mirror X-ray telescopes for the XMM mission was unveiled for the press in May 1997. When it goes into orbit in 1999 XMM will make, in seconds, observations of cosmic objects that took hours with previous X-ray astronomy missions. * The Hubble Space Telescope, in which ESA is a partner, continues to deliver the sharpest pictures of the

  14. ESA on RAINEWS24: A Case Study of Television Communication

    NASA Astrophysics Data System (ADS)

    Sandrelli, S.

    2005-12-01

    In May 2000, ESRIN, the Italian establishment of the European Space Agency (ESA), started a collaboration with the television channel Rainews24. Rainews24 is the "allnews" channel of Italian public television (RAI) and is now about 10 years old. It transmits 24 hours a day and is the most watched all-news satellite channel in Italy. Each Thursday an ESA representative (Stefano Sandrelli) is interviewed by a professional RAI journalist in a 5-6 minute long slot that follows the 5 pm news bulletin. The broadcast is repeated late at night or in the early hours of Thursday and Friday. Interviews are strictly linked to the weekly news and are prepared on the morning of the same day by the ESA representative in collaboration with a RAI journalist. The subject is chosen from the most topical news items of the week: video, images and animations are provided by the ESA television service and by press agencies (Reuters etc.). The interviews are largely informal and resemble a dialogue rather than an academic discussion "from space". Even though they focus on ESA activities, they are not advertisements: space science and research is dealt with as a human activity, so both the positive and negative aspects of space exploration and exploitation may emerge. Although this outreach activity began as an experiment, the ESA interviews have become a fixed feature. As a result of five years of uninterrupted collaboration, over 200 interviews have been recorded, with about 30% of the interviews dedicated to pure astronomy. A welcome positive feature is that the interviews are seen by Rainews24 as an open source of daily news.

  15. LINE ABSORPTION OSCILLATOR STRENGTHS FOR THE c'{sub 4}{sup 1}{Sigma}{sup +}{sub u}(3)-X{sup 1}{Sigma}{sup +}{sub g}(0-5) BANDS IN N{sub 2}

    SciTech Connect

    Lavin, C.; Velasco, A. M.

    2011-09-20

    Theoretical absorption oscillator strengths and emission branching ratios for rotational lines of the c'{sub 4}{sup 1}{Sigma}{sup +}{sub u}(3)-X{sup 1}{Sigma}{sup +}{sub g}(0-5) bands of molecular nitrogen are reported. The calculations have been performed with the molecular quantum defect orbital method, which has proved to be reliable in previous studies of rovibronic transitions in diatomic molecules. The strong interaction between c'{sub 4}{sup 1}{Sigma}{sup +}{sub u}(3) and b' {sup 1}{Sigma}{sup +}{sub u}(10) states has been analyzed through an interaction matrix that includes rotational terms. Owing to the perturbation, the c'{sub 4}{sup 1}{Sigma}{sup +}{sub u}(3)-X{sup 1}{Sigma}{sup +}{sub g}(0), c'{sub 4}{sup 1}{Sigma}{sup +}{sub u}(3)-X{sup 1}{Sigma}{sup +}{sub g}(1), and c'{sub 4}{sup 1}{Sigma}{sup +}{sub u}(3)-X{sup 1}{Sigma}{sup +}{sub g}(5) bands are not weak, in contrast to what would be expected on the basis of the Franck-Condon principle. Moreover, the intensity distribution of the rotational lines within each of the vibronic bands deviates from considerations based on Hoenl-London factors. In this work, we provide data that may be useful to interpret spectra from atmospheres of the Earth, Titan, and Triton, in which transitions from the c'{sub 4}{sup 1}{Sigma}{sup +}{sub u}(3) level have been detected.

  16. NASA's Preparations for ESA's L3 Gravitational Wave Mission

    NASA Astrophysics Data System (ADS)

    Stebbins, Robin T.

    2016-01-01

    In November 2013, the European Space Agency (ESA) selected the science theme, the "Gravitational Universe," for its third large mission opportunity, known as 'L3,' under its Cosmic Vision Programme. The planned launch date is 2034. NASA is seeking a role as an international partner in L3. NASA is supporting: (1) US participation in early mission studies, (2) US technology development, (3) pre-decadal preparations, (4) ESA's LISA Pathfinder mission and (5) the ST7 Disturbance Reduction System project. This talk summarizes NASA's preparations for a future gravitational-wave mission.

  17. Active optics for space applications: an ESA perspective

    NASA Astrophysics Data System (ADS)

    Zuccaro Marchi, Alessandro; Hallibert, Pascal; Pereira do Carmo, Joao; Wille, Eric

    2014-07-01

    Active optics for Space is relatively new field that takes advantage of lessons learnt on ground, and together with the tighter constrains of space environment it allows operation of larger mirrors apertures for space telescopes and better image quality. Technical developments are crucial to guarantee proper technological readiness for applications on new missions whose performance can be driven also by these novelties. This paper describes the philosophy pursued at ESA, providing an overview of the activities run within the Agency, as well as perspectives for new developments. The Optics Section of the Directorate of Technical and Quality Management of ESA/ESTEC is currently running three projects. Two examples are here addressed.

  18. ESA-SSA Review of Space Weather Measurement Requirements

    NASA Astrophysics Data System (ADS)

    Luntama, Juha-Pekka; Glover, Alexi; Hilgers, Alain

    2012-07-01

    The ESA Space Situational Awareness (SSA) Preparatory Programme was started in 2009. The objective of the programme is to support the European independent utilisation of and access to space. The first phase of the ESA SSA system development will be finished in 2012 and the next phase is foreseen to be started after the ESA Ministerial Council meeting in November 2012. The definition of measurement requirements for the Space Weather Segment (SWE) of the ESA SSA system has been based on the space weather service requirements defined the by expected users of the system. This document, SSA SWE Customer Requirements Document (CRD), has been defined in a iterative process together with the members of the SSA User Representative Group (URG) and the delegates representing the European states participating the programme. Based on the SWE CRD, ESA with the support of the European industry has produced two documents: SSA SWE System Requirements Document (SRD) and SSA SWE Product Specification (PS). SWE PS contains the requirements for the measurements data required by the SSA SWE system. The SWE PS document has been recently rigorously reviewed by the SSA URG in the framework of the SSA System Requirements Review (SRR). The support provided by the Steering Board of the ESA Space Weather Working Team (SWWT) in this review was extremely useful. The members of the SWWT SB representing the scientific community and the provisional service providers were able to give very detailed comments regarding the measurement requirements for accuracy, cadence, timeliness, etc. As these parameters will be provisional design and cost drivers for the ESA SSA system, definition of the appropriate values at this point in the programme is crucial. This paper provides an overview of the measurement requirements for the SWE Segment of the ESA SSA Programme. The paper discusses the requirement definition process, the customer and service provider inputs, and the critical requirements as they have

  19. HST's 10th anniversary, ESA and Hubble : changing our vision

    NASA Astrophysics Data System (ADS)

    2000-04-01

    With the astronauts who took part in the most recent Servicing Mission (SM3A) in attendance, ESA is taking the opportunity to give a - first - complete overview of Europe's major contribution to the HST mission. It will also review the first ten years of operations and the outstanding results that have "changed our vision" of the cosmos. A new fully European outreach initiative - the "European Space Agency Hubble Information Centre" - will be presented and officially launched; it has been set up by ESA to provide information on Hubble from a European perspective. A public conference will take place in the afternoon to celebrate Hubble's achievements midway through its life. Ten years of outstanding performance Launched on 24 April 1990, Hubble is now midway through its operating life and it is considered one of the most successful space science missions ever. So far more than 10,000 scientific papers based on Hubble results have been published and European scientists have contributed to more than 25% of these. Not only has Hubble produced a rich harvest of scientific results, it has impressed the man in the street with its beautiful images of the sky. Thousands of headlines all over the world have given direct proof of the public's great interest in the mission - 'The deepest images ever', 'The sharpest view of the Universe', 'Measurements of the earliest galaxies' and many others, all reflecting Hubble's performance as a top-class observatory. The Servicing Missions that keep the observatory and its instruments in prime condition are one of the innovative ideas behind Hubble. Astronauts have serviced Hubble three times, and ESA astronauts have taken part in two of these missions. Claude Nicollier (CH) worked with American colleagues on the First Servicing Mission, when Hubble's initial optical problems were repaired. On the latest, Servicing Mission 3A, both Claude Nicollier and Jean-François Clervoy (F) were members of the crew. Over the next 10 years European

  20. The ESA Scientific Exploitation of Operational Missions element

    NASA Astrophysics Data System (ADS)

    Desnos, Yves-Louis; Regner, Peter; Zehner, Claus; Engdahl, Marcus; Benveniste, Jerome; Delwart, Steven; Gascon, Ferran; Mathieu, Pierre-Philippe; Bojkov, Bojan; Koetz, Benjamin; Arino, Olivier; Donlon, Craig; Davidson, Malcolm; Goryl, Philippe; Foumelis, Michael

    2014-05-01

    The objectives of the ESA Scientific Exploitation of Operational Missions (SEOM) programme element are • to federate, support and expand the research community • to strengthen the leadership of European EO research community • to enable the science community to address new scientific research As a preparation for the SEOM element a series of international science users consultation has been organized by ESA in 2012 and 2013 In particular the ESA Living Planet Symposium was successfully organized in Edinburgh September 2013 and involving 1700 participants from 60 countries. The science users recommendations have been gathered and form the basis for the 2014 SEOM work plan approved by ESA member states. The SEOM element is organized along the following action lines: 1. Developing open-source, multi-mission, scientific toolboxes : the new toolboxes for Sentinel 1/2/3 and 5P will be introduced 2. Research and development studies: the first SEOM studies are being launched such as the INSARAP studies for Sentinel 1 interferometry in orbit demonstration , the IAS study to generate an improved spectroscopic database of the trace gas species CH4, H2O, and CO in the 2.3 μm region and SO2 in the UV region for Sentinel 5 P. In addition larger Sentinels for science call will be tendered in 2014 covering grouped studies for Sentinel 1 Land , Sentinel 1 Ocean , Sentinel 2 Land, Sentinel 3 SAR Altimetry ,Sentinel 3 Ocean color, Sentinel 3 Land and Sentinels Synergy . 3. Science users consultation : the Sentinel 2 for Science workshop is planned from 20 to 22 may 2014 at ESRIN to prepare for scientific exploitation of the Sentinel-2 mission (http://seom.esa.int/S2forScience2014 ) . In addition the FRINGE workshop focusing on scientific explotation of Sentinel1 using SAR interferometry is planned to be held at ESA ESRIN in Q2 2015 4. Training the next generation of European EO scientists on the scientific exploitation of Sentinels data: the Advanced Training course Land

  1. Band models and correlations for infrared radiation

    NASA Technical Reports Server (NTRS)

    Tiwari, S. N.

    1975-01-01

    Absorption of infrared radiation by various line and band models are briefly reviewed. Narrow band model relations for absorptance are used to develop 'exact' formulations for total absorption by four wide band models. Application of a wide band model to a particular gas largely depends upon the spectroscopic characteristic of the absorbing-emitting molecule. Seven continuous correlations for the absorption of a wide band model are presented and each one of these is compared with the exact (numerical) solutions of the wide band models. Comparison of these results indicate the validity of a correlation for a particular radiative transfer application. In radiative transfer analyses, use of continuous correlations for total band absorptance provides flexibilities in various mathematical operations.

  2. ESA's Venus Express to reach final destination

    NASA Astrophysics Data System (ADS)

    2006-04-01

    atmospheric bands in the infrared part of the spectrum. Through these, precious information about the lower layers of the atmosphere and even the surface can be gathered. The Venus Express mission will help find answers to several unsolved questions. How does the complex atmospheric dynamics and cloud system work? What causes the fast “super-rotation” of the atmosphere at the cloud top? And what is the origin of the double vortex at the north pole? Venus Express will also investigate the processes that determine the chemistry of the noxious Venusian atmosphere, which can be as hot as 500°C at the surface and is mainly composed of carbon dioxide, with clouds of sulphuric acid drops. It will study what role the greatest greenhouse effect in the solar system plays in the overall evolution of the Venusian climate. It will also help us to ascertain whether Venus provides a possible preview of a future Earth. Lastly, through combined analysis of the dense atmosphere and surface, Venus Express will help us to understand the planet’s geology and ascertain there are signs of present volcanic or seismic activity. “Venus Express to ground control” During the course of the nominal mission, Venus Express will communicate with Earth via ESA’s Cebreros ground station near Madrid. ESA’s New Norcia station in Australia will be used to support the VeRA radio science experiment.

  3. http://www.esa.int/esaSC/Pr_21_2004_s_en.html

    NASA Astrophysics Data System (ADS)

    2004-09-01

    X-ray brightness map hi-res Size hi-res: 38 Kb Credits: ESA/ XMM-Newton/ Patrick Henry et al. X-ray brightness map This map shows "surface brightness" or how luminous the region is. The larger of the two galaxy clusters is brighter, shown here as a white and red spot. A second cluster resides about "2 o'clock" from this, shown by a batch of yellow surrounded by green. Luminosity is related to density, so the densest regions (cluster cores) are the brightest regions. The white color corresponds to regions of the highest surface brightness, followed by red, orange, yellow, green, blue and purple. High resolution version (JPG format) 38 Kb High resolution version (TIFF format) 525 Kb Temperature map Credits: NASA Artist’s impression of cosmic head on collision The event details what the scientists are calling the perfect cosmic storm: galaxy clusters that collided like two high-pressure weather fronts and created hurricane-like conditions, tossing galaxies far from their paths and churning shock waves of 100-million-degree gas through intergalactic space. The tiny dots in this artist's concept are galaxies containing thousand million of stars. Animated GIF version Temperature map hi-res Size hi-res: 57 Kb Credits: ESA/ XMM-Newton/ Patrick Henry et al. Temperature map This image shows the temperature of gas in and around the two merging galaxy clusters, based directly on X-ray data. The galaxies themselves are difficult to identify; the image highlights the hot ‘invisible’ gas between the clusters heated by shock waves. The white colour corresponds to regions of the highest temperature - million of degrees, hotter than the surface of the Sun - followed by red, orange, yellow and blue. High resolution version (JPG format) 57 Kb High resolution version (TIFF format) 819 Kb The event details what the scientists are calling the ‘perfect cosmic storm’: galaxy clusters that collided like two high-pressure weather fronts and created hurricane-like conditions

  4. The ESA contribution to the European Satellite Navigation Programme

    NASA Astrophysics Data System (ADS)

    Lucas, R.; Lo Galbo, P.; de Mateo, M. L.; Steciw, A.; Ashford, E.

    1996-02-01

    This paper describes the ESA ARTES-9 programme on Global Navigation Satellite Systems (GNSS). This programme will be the ESA contribution to the wider European Satellite Navigation Programme which is to be implemented as a joint effort of the European Union, Eurocontrol and ESA with the support of other European bodies such as telecommunication operators, national civil aviation authorities, national space agencies, industry, universities and R&D institutes in general. In fact, in view of the geographical area concerned, the large number of parties interested, the experience required and the global nature of GNSS, the proposed initiative can only be successful if based on a strong cooperation at a European and international scale. The ESA ARTES-9 programme will consist on one side, of the design, development and validation of the European complement to the GPS and GLONASS systems (GNSS1), and on the other side of the study, design and pre-development of the European contribution to follow-on systems: GNSS2.

  5. SCOS2: ESA's new generation of mission control systems

    NASA Technical Reports Server (NTRS)

    Kaufeler, J. F.; Head, N. C.

    1993-01-01

    The paper describes the next generation Spacecraft Control System infrastructure (SCOSII) which is being developed at the Operations Centre (ESOC) of the European Space Agency (ESA). The objectives of the new system and selected areas of the proposed hardware and software approach are described.

  6. http://www.esa.int/esaSC/Pr_21_2004_s_en.html

    NASA Astrophysics Data System (ADS)

    2004-09-01

    X-ray brightness map hi-res Size hi-res: 38 Kb Credits: ESA/ XMM-Newton/ Patrick Henry et al. X-ray brightness map This map shows "surface brightness" or how luminous the region is. The larger of the two galaxy clusters is brighter, shown here as a white and red spot. A second cluster resides about "2 o'clock" from this, shown by a batch of yellow surrounded by green. Luminosity is related to density, so the densest regions (cluster cores) are the brightest regions. The white color corresponds to regions of the highest surface brightness, followed by red, orange, yellow, green, blue and purple. High resolution version (JPG format) 38 Kb High resolution version (TIFF format) 525 Kb Temperature map Credits: NASA Artist’s impression of cosmic head on collision The event details what the scientists are calling the perfect cosmic storm: galaxy clusters that collided like two high-pressure weather fronts and created hurricane-like conditions, tossing galaxies far from their paths and churning shock waves of 100-million-degree gas through intergalactic space. The tiny dots in this artist's concept are galaxies containing thousand million of stars. Animated GIF version Temperature map hi-res Size hi-res: 57 Kb Credits: ESA/ XMM-Newton/ Patrick Henry et al. Temperature map This image shows the temperature of gas in and around the two merging galaxy clusters, based directly on X-ray data. The galaxies themselves are difficult to identify; the image highlights the hot ‘invisible’ gas between the clusters heated by shock waves. The white colour corresponds to regions of the highest temperature - million of degrees, hotter than the surface of the Sun - followed by red, orange, yellow and blue. High resolution version (JPG format) 57 Kb High resolution version (TIFF format) 819 Kb The event details what the scientists are calling the ‘perfect cosmic storm’: galaxy clusters that collided like two high-pressure weather fronts and created hurricane-like conditions

  7. Observation of confinement effects through liner and nonlinear absorption spectroscopy in cuprous oxide

    NASA Astrophysics Data System (ADS)

    Sekhar, H.; Rakesh Kumar, Y.; Narayana Rao, D.

    2015-02-01

    Cuprous oxide nano clusters, micro cubes and micro particles were successfully synthesized by reducing copper (II) salt with ascorbic acid in the presence of sodium hydroxide via a co-precipitation method. The X-ray diffraction studies revealed the formation of pure single phase cubic. Raman spectrum shows the inevitable presence of CuO on the surface of the Cu2O powders which may have an impact on the stability of the phase. Transmission electron microscopy (TEM) data revealed that the morphology evolves from nanoclusters to micro cubes and micro particles by increasing the concentration of NaOH. Linear optical measurements show that the absorption peak maximum shifts towards red with changing morphology from nano clusters to micro cubes and micro particles. The nonlinear optical properties were studied using open aperture Z-scan technique with 532 nm, 6 ns laser pulses. Samples exhibited saturable as well as reverse saturable absorption. The results show that the transition from SA to RSA is ascribed to excited-state absorption (ESA) induced by two-photon absorption (TPA) process. Due to confinement effects (enhanced band gap) we observed enhanced nonlinear absorption coefficient (βeff) in the case of nano-clusters compared to their micro-cubes and micro-particles.

  8. Full Spectral Resolution Data Generation from the Cross-track Infrared Sounder on S-NPP at NOAA and its Use to Investigate Uncertainty in Methane Absorption Band Near 7.66 µm

    NASA Astrophysics Data System (ADS)

    Xiong, X.; Peischl, J.; Ryerson, T. B.; Sasakawa, M.; Han, Y.; Chen, Y.; Wang, L.; Tremblay, D.; Jin, X.; Zhou, L.; Liu, Q.; Weng, F.; Machida, T.

    2015-12-01

    The Cross-track Infrared Sounder (CrIS) on Suomi National Polar-orbiting Partnership Satellite (S-NPP) is a Fourier transform spectrometer for atmospheric sounding. CrIS on S-NPP started to provide measurements in 1305 channels in its normal mode since its launch on November 2011 to December 4, 2014, and after that it was switched to the full spectral resolution (FSR) mode, in which the spectral resolutions are 0.625 cm-1 in all the MWIR (1210-1750 cm-1), SWIR (2155-2550 cm-1) and the LWIR bands (650-1095 cm-1) with a total of 2211 channels. While the NOAA operational Sensor Data Record (SDR) processing (IDPS) continues to produce the normal resolution SDRs by truncating full spectrum RDR data, NOAA STAR started to process the FSR SDRs data since December 4, 2014 to present, and the data is being delivered through NOAA STAR website (ftp://ftp2.star.nesdis.noaa.gov/smcd/xxiong/). The current FSR processing algorithm was developed on basis of the CrIS Algorithm Development Library (ADL), and is the baseline of J-1 CrIS SDR algorithm. One major benefit to use the FSR data is to improve the retrieval of atmospheric trace gases, such as CH4, CO and CO2 . From our previous studies to retrieve CH4 using Atmospheric Infrared Sounder (AIRS) and Infrared Atmospheric Sounding Interferometer (IASI), it was found the uncertainty in the CH4 absorption band is up to 1-2%. So, in this study we computed the radiance using the community radiative transfer model (CRTM) and line-by-line model, with the inputs of "truth" of atmospheric temperature and moisture profiles from ECMWF model (and/or RAOB sounding) and CH4 profiles from in-situ aircraft measurements, then convoluted with the response function of CrIS. The difference between the simultaed radiance and the collocated CrIS FSR data is used to exam the uncertainty in these strong absorption channels.Through the improved fitting to the transmittance in these channels, it is expected to improve the retrieval of CH4 using CrIS on S

  9. Broadband transient absorption spectroscopy with 1- and 2-photon excitations: Relaxation paths and cross sections of a triphenylamine dye in solution

    SciTech Connect

    Moreno, J.; Dobryakov, A. L.; Hecht, S. E-mail: skovale@chemie.hu-berlin.de; Kovalenko, S. A. E-mail: skovale@chemie.hu-berlin.de; Ioffe, I. N.; Granovsky, A. A.

    2015-07-14

    1-photon (382 nm) and 2-photon (752 nm) excitations to the S{sub 1} state are applied to record and compare transient absorption spectra of a push-pull triphenylamine (TrP) dye in solution. After 1-photon excitation, ultrafast vibrational and structural molecular relaxations are detected on a 0.1 ps time scale in nonpolar hexane, while in polar acetonitrile, the spectral evolution is dominated by dipolar solvation. Upon 2-photon excitation, transient spectra in hexane reveal an unexpected growth of stimulated emission (SE) and excited-state absorption (ESA) bands. The behavior is explained by strong population transfer S{sub 1} → S{sub n} due to resonant absorption of a third pump photon. Subsequent S{sub n} → S{sub 1} internal conversion (with τ{sub 1} = 1 ps) prepares a very hot S{sub 1} state which cools down with τ{sub 2} = 13 ps. The pump pulse energy dependence proves the 2-photon origin of the bleach signal. At the same time, SE and ESA are strongly affected by higher-order pump absorptions that should be taken into account in nonlinear fluorescence applications. The 2-photon excitation cross sections σ{sup (2)} = 32 ⋅ 10{sup −50} cm{sup 4} s at 752 nm are evaluated from the bleach signal.

  10. Broadband transient absorption spectroscopy with 1- and 2-photon excitations: Relaxation paths and cross sections of a triphenylamine dye in solution

    NASA Astrophysics Data System (ADS)

    Moreno, J.; Dobryakov, A. L.; Ioffe, I. N.; Granovsky, A. A.; Hecht, S.; Kovalenko, S. A.

    2015-07-01

    1-photon (382 nm) and 2-photon (752 nm) excitations to the S1 state are applied to record and compare transient absorption spectra of a push-pull triphenylamine (TrP) dye in solution. After 1-photon excitation, ultrafast vibrational and structural molecular relaxations are detected on a 0.1 ps time scale in nonpolar hexane, while in polar acetonitrile, the spectral evolution is dominated by dipolar solvation. Upon 2-photon excitation, transient spectra in hexane reveal an unexpected growth of stimulated emission (SE) and excited-state absorption (ESA) bands. The behavior is explained by strong population transfer S1 → Sn due to resonant absorption of a third pump photon. Subsequent Sn → S1 internal conversion (with τ1 = 1 ps) prepares a very hot S1 state which cools down with τ2 = 13 ps. The pump pulse energy dependence proves the 2-photon origin of the bleach signal. At the same time, SE and ESA are strongly affected by higher-order pump absorptions that should be taken into account in nonlinear fluorescence applications. The 2-photon excitation cross sections σ(2) = 32 ṡ 10-50 cm4 s at 752 nm are evaluated from the bleach signal.

  11. IRRS, UV-Vis-NIR absorption and photoluminescence upconversion in Ho 3+-doped oxyfluorophosphate glasses

    NASA Astrophysics Data System (ADS)

    Karmakar, Basudeb

    2005-09-01

    Infrared reflection spectroscopic (IRRS), ultraviolet-visible-near infrared (UV-Vis-NIR) absorption and photoluminescence upconversion properties with special emphasis on the spectrochemistry of the oxyfluorophosphate (oxide incorporated fluorophosphates) glasses of the Ba(PO 3) 2-AlF 3-CaF 2-SrF 2-MgF 2-Ho 2O 3 system have been studied with different concentrations (0.1, 0.3 and 1.0 mol%) of Ho 2O 3. IRRS spectral band position and intensity of Ho 3+ ion doped oxyfluorophosphate glasses have been discussed in terms of reduced mass and force constant. UV-Vis-NIR absorption band position has been justified with quantitative calculation of nephelauxetic parameter and covalent bonding characteristics of the host. NIR to visible upconversion has been investigated by exciting at 892 nm at room temperature. Three upconverted bands originated from the 5F 3→ 5I 8, ( 5S 2, 5F 4)→ 5I 8 and 5F 5→ 5I 8 transitions have found to be centered at 491 nm (blue, medium), 543 nm (green, very strong) and 658 nm (red, weak), respectively. These bands have been justified from the evaluation of the absorption, normal (down conversion) fluorescence and excitation spectra. The upconversion processes have been explained by the excited state absorption (ESA), energy transfer (ET) and cross relaxation (CR) mechanisms involving population of the metastable (storage) energy levels by multiphonon deexcitation effect. It is evident from the IRRS study that the upconversion phenomena are expedited by the low multiphonon relaxation rate in oxyfluorophosphate glasses owing to their high intense low phonon energy (˜600 cm -1) which is very close to that of fluoride glasses (500-600 cm -1).

  12. L(alpha)-induced two-photon absorption of visible light emitted from an O-type star by H2(+) ions located near the surface of the Stromgren sphere surrounding the star: A possible explanation for the diffuse interstellar absorption bands (DIDs)

    NASA Technical Reports Server (NTRS)

    Glownia, James H.; Sorokin, Peter P.

    1994-01-01

    In this paper, a new model is proposed to account for the DIB's (Diffuse Interstellar Bands). In this model, the DIB's result from a non-linear effect: resonantly-enhanced two-photon absorption of H(2+) ions located near the surface of the Stromgren sphere that surrounds an O- or B- type star. The strong light that is required to 'drive' the two-photon transition is provided by L(alpha) light emerging from the Stromgren sphere that bounds the H II region surrounding the star. A value of approximately 100 micro W/sq cm is estimated for the L(alpha) flux at the Stromgren radius, R(s), of a strong (O5) star. It is shown that a c.w. L(alpha) flux of this intensity should be sufficient to induce a few percent absorption for visible light radiated by the same star at a frequency (omega2) that completes an allowed two-photon transition, provided (1) the L(alpha) radiation happens to be nearly resonant with the frequency of a fully-allowed absorber transition that effectively represents the first step in the two-photon transition, and (2) an effective column density approximately 10(sup18)/sq cm of the absorber is present near the Stromgren sphere radius, R(sub s).

  13. Joint NASA-ESA Outer Planet Mission study overview

    NASA Astrophysics Data System (ADS)

    Lebreton, J.-P.; Niebur, C.; Cutts, J.; Falkner, P.; Greeley, R.; Lunine, J.; Blanc, M.; Coustenis, A.; Pappalardo, R.; Matson, D.; Clark, K.; Reh, K.; Stankov, A.; Erd, C.; Beauchamp, P.

    2009-04-01

    In 2008, ESA and NASA performed joint studies of two highly capable scientific missions to the outer planets: the Europa Jupiter System Mission (EJSM) and the Titan Saturn System Mission (TSSM). Joint Science Definition Teams (JSDTs) were formed with U.S. and European membership to guide study activities that were conducted collaboratively by engineering teams working on both sides of the Atlantic. EJSM comprises the Jupiter Europa Orbiter (JEO) that would be provided by NASA and the Jupiter Ganymede Orbiter (JGO) that would be provided by ESA. Both spacecraft would be launched independently in 2020, and arrive 6 years later for a 3-4 year mission within the Jupiter System. Both orbiters would explore Jupiter's system on trajectories that include flybys of Io (JEO only), Europa (JEO only), Ganymede and Callisto. The operation of JEO would culminate in orbit around Europa while that of JGO would culminate in orbit around Ganymede. Synergistic and coordinated observations would be planned. The Titan Saturn System Mission (TSSM) comprises a Titan Orbiter provided by NASA that would carry two Titan in situ elements provided by ESA: the montgolfière and the lake lander. The mission would launch in 2020 and arrive 9 years later for a 4-year duration in the Saturn system. Following delivery of the ESA in situ elements to Titan, the Titan Orbiter would explore the Saturn system via a 2-year tour that includes Enceladus and Titan flybys. The montgolfière would last at least 6-12 months at Titan and the lake lander 8-10 hours. Following the Saturn system tour, the Titan Orbiter would culminate in a ~2-year orbit around Titan. Synergistic and coordinated observations would be planned between the orbiter and in situ elements. The ESA contribution to this joint endeavor will be implemented as the first Cosmic Vision Large-class (L1) mission; the NASA contribution will be implemented as the Outer Planet Flagship Mission. The contribution to each mission is being reviewed and

  14. Demonstrating xLuna on ESA EXOMADER Rover

    NASA Astrophysics Data System (ADS)

    Braga, P.

    2012-01-01

    In this article we present xLuna [1] and its successful demonstration on the ESA EXOMArs DEmonstration Rover (EXOMADER) [2]. xLuna is a Linux-specific hypervisor extension for RTEMS, a Real-time Executive already used on ESA missions. On xLuna, RTEMS runs natively and directly on top of the hardware providing all its native services to real- time control applications. On top of the hypervisor runs a Linux kernel para-virtualised specifically for the system that provides all the well known POSIX based services and an endless set of software libraries to payload applications. On the demonstration, the complete navigation software of the rover (with stereo image processing and path processing) that was being tested ran on xLuna's Linux subsystem, while the RTEMS components were running control tasks. Due to impossibilities of integration, the RTEMS tasks running were simulated. The control was performed by existing HW.

  15. The non-linearity of the ESA Photon Counting Detector

    NASA Astrophysics Data System (ADS)

    Llebaria, A.; Nieto, J.-L.; di Serego Alighieri, S.

    1986-11-01

    The time-resolved imaging mode (TRIM) suggested by di Serego Alighieri and Perryman (1986), in which photons are recorded separately on each television camera frame, was used to analyze the data obtained in 1984 on the nucleus of M31 with the ESA Photon Counting Detector (PCD) on the Canada-France-Hawaii telescope. Through the examination of the TRIM data, it was possible to detect nonlinearity in the response of the ESA PCD, which is interpreted as being due to phosphorescence in the intensifier. A quantitative measurement of this effect is shown. It is argued that if the interpretation is correct, the same kind of nonlinearity should be found in all photon counting detectors with phosphor screen. The amount of the nonlinearity is presumably higher in detectors with lower thresholds.

  16. AM1/CI, CNDO/S and ZINDO/S computations of absorption bands and their intensities in the UV spectra of some 4(3H)-quinazolinones

    NASA Astrophysics Data System (ADS)

    Eshimbetov, A. G.; Kristallovich, E. L.; Abdullaev, N. D.; Tulyaganov, T. S.; Shakhidoyatov, Kh. M.

    2006-10-01

    A detailed analysis of both frontier MOs and electronic transitions in UV spectra of 16 4-quinazolinone derivatives has been carried out in MO terms, by semiempirical methods AM1/CI, CNDO/S and ZINDO/S. On the basis of experimental and theoretical investigations by the ZINDO/S and CNDO/S methods the long-wavelength bands of 4(3H)-quinazolinone and its derivatives have been assigned to n → π* transition of the lbond2 C dbnd O fragment and to the transition caused by intramolecular charge transfer from Ph and N dbnd C sbnd N fragments to lbond2 C dbnd O group. It was shown that theoretically obtained electronic transitions applying method AM1/CI are not in agreement with experimental data observed for the 4(3H)-quinazolinone and 2,4(1H,3H)-quinazolinedione. Good correlation of theoretical and experimental data has been obtained by the method ZINDO/S for the wavelengths and the molar extinction coefficients of the compounds studied. Satisfactory correlation of theoretical and experimental data has also been obtained by the method CNDO/S with singly and doubly excited configurations, for the wavelengths only. Such correlations on experimental and theoretical wavelength and molar absorption coefficients of 4-quinazolinone derivatives are carried out for the first time.

  17. AM1/CI, CNDO/S and ZINDO/S computations of absorption bands and their intensities in the UV spectra of some 4(3H)-quinazolinones.

    PubMed

    Eshimbetov, A G; Kristallovich, E L; Abdullaev, N D; Tulyaganov, T S; Shakhidoyatov, Kh M

    2006-10-01

    A detailed analysis of both frontier MOs and electronic transitions in UV spectra of 16 4-quinazolinone derivatives has been carried out in MO terms, by semiempirical methods AM1/CI, CNDO/S and ZINDO/S. On the basis of experimental and theoretical investigations by the ZINDO/S and CNDO/S methods the long-wavelength bands of 4(3H)-quinazolinone and its derivatives have been assigned to n-->pi(*) transition of the CO fragment and to the transition caused by intramolecular charge transfer from Ph and NCN fragments to CO group. It was shown that theoretically obtained electronic transitions applying method AM1/CI are not in agreement with experimental data observed for the 4(3H)-quinazolinone and 2,4(1H,3H)-quinazolinedione. Good correlation of theoretical and experimental data has been obtained by the method ZINDO/S for the wavelengths and the molar extinction coefficients of the compounds studied. Satisfactory correlation of theoretical and experimental data has also been obtained by the method CNDO/S with singly and doubly excited configurations, for the wavelengths only. Such correlations on experimental and theoretical wavelength and molar absorption coefficients of 4-quinazolinone derivatives are carried out for the first time. PMID:16495133

  18. ESA SMART-1 mission: review of results and legacy 10 years after launch

    NASA Astrophysics Data System (ADS)

    Foing, Bernard

    2014-05-01

    We review ESA's SMART-1 highlights and legacy 10 years after launch. The SMART-1 mission to the Moon achieved record firsts such as: 1) first Small Mission for Advanced Research and Technology; with spacecraft built and integrated in 2.5 years and launched 3.5 years after mission approval; 2) first mission leaving the Earth orbit using solar power alone with demonstration for future deep space missions such as BepiColombo; 3) most fuel effective mission (60 litres of Xenon) and longest travel (13 month) to the Moon!; 4) first ESA mission reaching the Moon and first European views of lunar poles; 5) first European demonstration of a wide range of new technologies: Li-Ion modular battery, deep-space communications in X- and Ka-bands, and autonomous positioning for navigation; 6) first lunar demonstration of an infrared spectrometer and of a Swept Charge Detector Lunar X-ray fluorescence spectrometer ; 7) first ESA mission with opportunity for lunar science, elemental geochemistry, surface mineralogy mapping, surface geology and precursor studies for exploration; 8) first controlled impact landing on the Moon with real time observations campaign; 9) first mission supporting goals of the ILEWG/COSPAR International Lunar Exploration Working Group in technical and scientific exchange, international collaboration, public and youth engagement; 10) first mission preparing the ground for ESA collaboration in Chandrayaan-1, Chang'E1-2-3 and near-future landers, sample return and human lunar missions. The SMART-1 technology legacy is applicable to geostationary satellites and deep space missions using solar electric propulsion. The SMART-1 archive observations have been used to support scientific research and prepare subsequent lunar missions and exploration. Most recent SMART-1 results are relevant to topics on: 1) the study of properties of the lunar dust, 2) impact craters and ejecta, 3) the study of illumination, 4) observations and science from the Moon, 5) support to

  19. ESA SMART-1 mission: results and lessons for future lunar exploration

    NASA Astrophysics Data System (ADS)

    Foing, Bernard H.

    We review ESA’s SMART-1 highlights and legacy 10 years after launch. We discuss lessons for future lunar exploration and upcoming missions. The SMART-1 mission to the Moon achieved record firsts such as: 1) first Small Mission for Advanced Research and Technology; with spacecraft built and integrated in 2.5 years and launched 3.5 years after mission approval; 2) first mission leaving the Earth orbit using solar power alone with demonstration for future deep space missions such as BepiColombo; 3) most fuel effective mission (60 litres of Xenon) and longest travel (13 month) to the Moon!; 4) first ESA mission reaching the Moon and first European views of lunar poles; 5) first European demonstration of a wide range of new technologies: Li-Ion modular battery, deep-space communications in X- and Ka-bands, and autonomous positioning for navigation; 6) first lunar demonstration of an infrared spectrometer and of a Swept Charge Detector Lunar X-ray fluorescence spectrometer ; 7) first ESA mission with opportunity for lunar science, elemental geochemistry, surface mineralogy mapping, surface geology and precursor studies for exploration; 8) first controlled impact landing on the Moon with real time observations campaign; 9) first mission supporting goals of the ILEWG/COSPAR International Lunar Exploration Working Group in technical and scientific exchange, international collaboration, public and youth engagement; 10) first mission preparing the ground for ESA collaboration in Chandrayaan-1, Chang’ E1-2-3 and near-future landers, sample return and human lunar missions. The SMART-1 technology legacy is applicable to application geostationary missions and deep space missions using solar electric propulsion. The SMART-1 archive observations have been used to support scientific research and prepare subsequent lunar missions. Most recent SMART-1 results are relevant to topics on: 1) the study of properties of the lunar dust, 2) impact craters and ejecta, 3) the study of

  20. ESA space spin-offs benefits for the health sector

    NASA Astrophysics Data System (ADS)

    Szalai, Bianca; Detsis, Emmanouil; Peeters, Walter

    2012-11-01

    Humanity will be faced with an important number of future challenges, including an expansion of the lifespan, a considerable increase of the population (estimated 9 billion by 2050) and a depletion of resources. These factors could trigger an increase of chronic diseases and various other health concerns that would bear a heavy weight on finances worldwide. Scientific advances can play an important role in solving a number of these problems, space technology; in general, can propose a panoply of possible solutions and applications that can make life on Earth easier and better for everyone. Satellites, Earth Observation, the International Space Station (ISS) and the European Space Agency (ESA) may not be the first tools that come to mind when thinking of improving health, yet there are many ways in which ESA and its programmes contribute to the health care arena. The research focuses on quantifying two ESA spin-offs to provide an initial view on how space can contribute to worldwide health. This quantification is part of the present strategy not only to show macroeconomic return factors for space in general, but also to identify and describe samples of 'best practice' type of examples close to the general public's interest. For each of the 'best practices' the methodology takes into account the cost of the space hardware/software, a number of tangible and intangible benefits, as well as some logical assumptions in order to determine the potential overall returns. Some of the hindering factors for a precise quantification are also highlighted. In conclusion, the study recommends a way in which ESA's spin-offs can be taken into account early on in the development process of space programmes in order to generate higher awareness with the general public and also to provide measurable returns.

  1. ESA/ESTEC Meteor Research Group - behind the scenes

    NASA Astrophysics Data System (ADS)

    Rudawska, R.

    2016-01-01

    The ESA/ESTEC Meteor Research Group consists of a team people with one goal: understand the effects of meteoric phenomena on planetary atmospheres and surfaces, as well as on spacecraft. The team carries out observational and theoretical studies in order to increase our knowledge of the small particle complex in the solar system. This talk addresses a number of tasks within the group seen from a perspective of a research fellow.

  2. Strengthening the Security of ESA Ground Data Systems

    NASA Astrophysics Data System (ADS)

    Flentge, Felix; Eggleston, James; Garcia Mateos, Marc

    2013-08-01

    A common approach to address information security has been implemented in ESA's Mission Operations (MOI) Infrastructure during the last years. This paper reports on the specific challenges to the Data Systems domain within the MOI and how security can be properly managed with an Information Security Management System (ISMS) according to ISO 27001. Results of an initial security risk assessment are reported and the different types of security controls that are being implemented in order to reduce the risks are briefly described.

  3. NASA/ESA CV-990 Spacelab Simulation (ASSESS 2)

    NASA Technical Reports Server (NTRS)

    Mulholland, D. R.; Androes, G. M.; Reeves, J. F.

    1978-01-01

    To test the validity of the ARC approach to Spacelab, several missions simulating aspects of Spacelab operations have been conducted as part of the ASSESS Program. Each mission was designed to evaluate potential Shuttle/Spacelab concepts in increasing detail. For this mission, emphasis was placed on development and exercise of management techniques planned for Spacelab using management participants from NASA and ESA who have responsibilities for Spacelab 1 which will be launched in 1980.

  4. SNAP (Sentinel Application Platform) and the ESA Sentinel 3 Toolbox

    NASA Astrophysics Data System (ADS)

    Zuhlke, Marco; Fomferra, Norman; Brockmann, Carsten; Peters, Marco; Veci, Luis; Malik, Julien; Regner, Peter

    2015-12-01

    ESA is developing three new free open source Toolboxes for the scientific exploitation of the Sentinel-1, Sentinel-2 and Sentinel-3 missions. The Toolboxes are based on a common software platform, namely the Sentinel Application Platform (SNAP). SNAP is an evolution of the proven ESA BEAM/NEST architecture inheriting all current BEAM and NEST functionality including multi-mission support for SAR and optical missions to support ESA and third party missions for years to come. The Sentinel-3 Toolbox includes generic function for visualisation and analysis of Sentinel-3 OLCI and SLSTR Level 1 and Level 2 data, as well as specific processing tools such as cloud screening, water constituent retrieval and SST retrieval. The Toolbox will put emphasis on access to remote in-situ databases such as Felyx or MERMAID, and exploitation of the data-uncertainty information which is included in the Sentinel-3 data products. New image classification, segmentation and filtering methods, as well as interoperability with the ORFEO Toolbox and the GDAL libraries will be additional new tools. New challenges stemming from Sentinel-3 sensors, such as raster data in different resolutions within a single dataset, will be supported gracefully. The development of SNAP and the Sentinel Toolboxes is funded through the “Scientific Exploitation of Operational Missions (SEOM)” programme, a new programme element of ESA’s fourth period of the Earth Observation Envelope Programme (2013-2017).

  5. ESA Intermediate Experimental Vehicle. Independent Aerothermodynamic Characterization And Aerodatabase Development

    NASA Astrophysics Data System (ADS)

    Rufolo, Giuseppe C.; Di Benedetto, Sara; Walpot, Louis; Roncioni, Pietro; Marini, Marco

    2011-05-01

    In the frame of the Intermediate eXperimental Vehicle (IXV) project, the European Space Agency (ESA) is coordinating a series of technical assistance activities aimed at verifying and supporting the IXV industrial design and development process. The technical assistance is operated with the support of the Italian Space Agency (ASI), by means of the Italian Aerospace Research Center (CIRA), and the European Space Research and Technology Centre (ESTEC) under the super visioning and coordination of ESA IXV team. One of the purposes of the activity is to develop an independent capability for the assessment and verification of the industrial results with respect to the aerothermodynamic characterization of the IXV vehicle. To this aim CIRA is developing and independent AeroThermodynamics DataBase (ATDB), intended as a tool generating in output the time histories of local quantities (heat flux, pressure, skin friction) for each point of the IXV vehicle and for each trajectory (in a pre-defined envelope), together with an uncertainties model. The reference Computational Fluid Dynamics (CFD) solutions needed for the development of the tool have been provided by ESA-ESTEC (with the CFD code LORE) and CIRA (with the CFD code H3NS).

  6. ESA DUE GlobVapour water vapor products: Validation

    NASA Astrophysics Data System (ADS)

    Schneider, Nadine; Schröder, Marc; Lindstrot, Ramus; Preusker, Rene; Stengel, Martin; ESA DUE GlobVapour Consortium

    2013-05-01

    The main objective of the European Space Agency (ESA) Data User Element (DUE) GlobVapour project was the development of multi-annual global water vapor data sets. Since water vapour is a key climate variable it is important to have a good understanding of its behavior in the climate system. The ESA DUE GlobVapour project provides water vapor data, including error estimates, based on carefully calibrated and inter-calibrated satellite radiances in response to user requirements for long time series satellite observations. ESA DUE GlobVapour total columnar water vapor (TCWV) products derived from GOME/SCIA/GOME-2 (1996-2008) and SSM/I+MERIS (2003-2008) have been validated for the mentioned period, using satellite-based (AIRS, ATOVS) and ground-based measurements (radiosondes and microwave radiometer). The validation results are discussed in the following. The technical specifications on bias (1 kg/m2 for SSMI+MERIS and 2 kg/m2 for GOME/SCIA/GOME-2) are generally met. For more information, documents and data download follow the link: www.globvapour.info.

  7. ESA DUE GlobVapour water vapor products: Validation

    SciTech Connect

    Schneider, Nadine; Schroeder, Marc; Stengel, Martin; Lindstrot, Ramus; Preusker, Rene; Collaboration: ESA DUE GlobVapour Consortium

    2013-05-10

    The main objective of the European Space Agency (ESA) Data User Element (DUE) GlobVapour project was the development of multi-annual global water vapor data sets. Since water vapour is a key climate variable it is important to have a good understanding of its behavior in the climate system. The ESA DUE GlobVapour project provides water vapor data, including error estimates, based on carefully calibrated and inter-calibrated satellite radiances in response to user requirements for long time series satellite observations. ESA DUE GlobVapour total columnar water vapor (TCWV) products derived from GOME/SCIA/GOME-2 (1996-2008) and SSM/I+MERIS (2003-2008) have been validated for the mentioned period, using satellite-based (AIRS, ATOVS) and ground-based measurements (radiosondes and microwave radiometer). The validation results are discussed in the following. The technical specifications on bias (1 kg/m{sup 2} for SSMI+MERIS and 2 kg/m{sup 2} for GOME/SCIA/GOME-2) are generally met. For more information, documents and data download follow the link: www.globvapour.info.

  8. SMART-1 Technology and Science Experiments in Preparation of Future Missions and ESA Cornerstones

    NASA Astrophysics Data System (ADS)

    Marini, A. E.; Racca, G. D.; Foing, B. H.; SMART-1 Project

    1999-12-01

    SMART-1 is the first ESA Small Mission for Advanced Research in Technology, aimed at the demonstration of enabling technologies for future scientific missions. SMART-1's prime technology objective is the demonstration of the solar primary electric propulsion, a key for future interplanetary missions. SMART-1 will use a Stationary Plasma Thruster engine, cruising 15 months to capture a Moon polar orbit. A gallery of images of the spacecraft is available at the web site: http://www.estec.esa.nl/spdwww/smart1/html/11742.html SMART-1 payload aims at monitoring the electric propulsion and its spacecraft environment and to test novel instrument technologies. The Diagnostic Instruments include SPEDE, a spacecraft potential plasma and charged particles detector, to characterise both spacecraft and planetary environment, together with EPDP, a suite of sensors monitoring secondary thrust-ions, charging and deposition effects. Innovative spacecraft technologies will be tested on SMART-1 : Lithium batteries and KATE, an experimental X/Ka-band deep-space transponder, to support radio-science, to monitor the accelerations of the electric propulsion and to test turbo-code technique, enhancing the return of scientific data. The scientific instruments for imaging and spectrometry are: \\begin{itemize} D-CIXS, a compact X-ray spectrometer based on novel SCD detectors and micro-structure optics, to observe X-ray celectial objects and to perform lunar chemistry measurements. SIR, a miniaturised quasi-monolithic point-spectrometer, operating in the Near-IR (0.9 ÷ 2.4 micron), to survey the lunar crust in previously uncovered optical regions. AMIE, a miniature camera based on 3-D integrated electronics, imaging the Moon, and other bodies and supporting LASER-LINK and RSIS. RSIS and LASER-LINK are investigations performed with the SMART-1 Payload: \\begin{itemize} RSIS: A radio-science Experiment to validate in-orbit determination of the libration of the celestial target, based on high

  9. The Software Architecture of the Upgraded ESA DRAMA Software Suite

    NASA Astrophysics Data System (ADS)

    Kebschull, Christopher; Flegel, Sven; Gelhaus, Johannes; Mockel, Marek; Braun, Vitali; Radtke, Jonas; Wiedemann, Carsten; Vorsmann, Peter; Sanchez-Ortiz, Noelia; Krag, Holger

    2013-08-01

    In the beginnings of man's space flight activities there was the belief that space is so big that everybody could use it without any repercussions. However during the last six decades the increasing use of Earth's orbits has lead to a rapid growth in the space debris environment, which has a big influence on current and future space missions. For this reason ESA issued the "Requirements on Space Debris Mitigation for ESA Projects" [1] in 2008, which apply to all ESA missions henceforth. The DRAMA (Debris Risk Assessment and Mitigation Analysis) software suite had been developed to support the planning of space missions to comply with these requirements. During the last year the DRAMA software suite has been upgraded under ESA contract by TUBS and DEIMOS to include additional tools and increase the performance of existing ones. This paper describes the overall software architecture of the ESA DRAMA software suite. Specifically the new graphical user interface, which manages the five main tools ARES (Assessment of Risk Event Statistics), MIDAS (MASTER-based Impact Flux and Damage Assessment Software), OSCAR (Orbital Spacecraft Active Removal), CROC (Cross Section of Complex Bodies) and SARA (Re-entry Survival and Risk Analysis) is being discussed. The advancements are highlighted as well as the challenges that arise from the integration of the five tool interfaces. A framework had been developed at the ILR and was used for MASTER-2009 and PROOF-2009. The Java based GUI framework, enables the cross-platform deployment, and its underlying model-view-presenter (MVP) software pattern, meet strict design requirements necessary to ensure a robust and reliable method of operation in an environment where the GUI is separated from the processing back-end. While the GUI framework evolved with each project, allowing an increasing degree of integration of services like validators for input fields, it has also increased in complexity. The paper will conclude with an outlook on

  10. The ESA Scientific Exploitation of Operational Missions element, first results

    NASA Astrophysics Data System (ADS)

    Desnos, Yves-Louis; Regner, Peter; Delwart, Steven; Benveniste, Jerome; Engdahl, Marcus; Mathieu, Pierre-Philippe; Gascon, Ferran; Donlon, Craig; Davidson, Malcolm; Pinnock, Simon; Foumelis, Michael; Ramoino, Fabrizio

    2016-04-01

    SEOM is a program element within the fourth period (2013-2017) of ESA's Earth Observation Envelope Programme (http://seom.esa.int/). The prime objective is to federate, support and expand the international research community that the ERS, ENVISAT and the Envelope programmes have built up over the last 25 years. It aims to further strengthen the leadership of the European Earth Observation research community by enabling them to extensively exploit future European operational EO missions. SEOM will enable the science community to address new scientific research that are opened by free and open access to data from operational EO missions. Based on community-wide recommendations for actions on key research issues, gathered through a series of international thematic workshops and scientific user consultation meetings, a work plan is established and is approved every year by ESA Members States. During 2015 SEOM, Science users consultation workshops have been organized for Sentinel1/3/5P ( Fringe, S3 Symposium and Atmospheric science respectively) , new R&D studies for scientific exploitation of the Sentinels have been launched ( S3 for Science SAR Altimetry and Ocean Color , S2 for Science,) , open-source multi-mission scientific toolboxes have been launched (in particular the SNAP/S1-2-3 Toolbox). In addition two advanced international training courses have been organized in Europe to exploit the new S1-A and S2-A data for Land and Ocean remote sensing (over 120 participants from 25 countries) as well as activities for promoting the first scientific results ( e.g. Chili Earthquake) . In addition the First EO Open Science 2.0 was organised at ESA in October 2015 with 225 participants from 31 countries bringing together young EO scientists and data scientists. During the conference precursor activities in EO Open Science and Innovation were presented, while developing a Roadmap preparing for future ESA scientific exploitation activities. Within the conference, the first

  11. Dual band metamaterial perfect absorber based on artificial dielectric "molecules".

    PubMed

    Liu, Xiaoming; Lan, Chuwen; Li, Bo; Zhao, Qian; Zhou, Ji

    2016-01-01

    Dual band metamaterial perfect absorbers with two absorption bands are highly desirable because of their potential application areas such as detectors, transceiver system, and spectroscopic imagers. However, most of these dual band metamaterial absorbers proposed were based on resonances of metal patterns. Here, we numerically and experimentally demonstrate a dual band metamaterial perfect absorber composed of artificial dielectric "molecules" with high symmetry. The artificial dielectric "molecule" consists of four "atoms" of two different sizes corresponding to two absorption bands with near unity absorptivity. Numerical and experimental absorptivity verify that the dual-band metamaterial absorber is polarization insensitive and can operate in wide-angle incidence. PMID:27406699

  12. Mission to Mars set to revolutionise ESA's working methods

    NASA Astrophysics Data System (ADS)

    1999-03-01

    ESA took the decision in principle to send a mission to Mars shortly after the loss of the Russian spacecraft Mars '96 with several European experiments on board. The Agency wanted to build on the Mars '96 payload experience to design a mission that would put Europe at the leading-edge of Mars exploration. But ESA had to act quickly. Major space missions can take up to 11 years from concept to launch - and there was little more than six years to go before the positioning of the planets in 2003 would offer the shortest travel time to Mars with the highest payload. Budgetary pressures were also forcing ESA to look for cheaper ways of building spacecraft. A Mars mission therefore seemed a good candidate to explore cheaper and faster working methods. Mars Express (so called because of the streamlined development time) is the first of a new type of "flexible" missions in ESA's long-term scientific programme, which should be built and launched for about half the previous budget for similar missions. The global budget for Mars Express will actually be only150 million Euro including spacecraft development, launch by a Russian Soyuz/Fregat launcher, operations, testing and management costs. Costs are being saved by shortening the time from original concept to launch, re-using existing hardware, adopting new project management practices, and having access to reduced launcher costs. Selection of the scientific payload by ESA's scientific advisory bodies and mission definition by industry have been performed simultaneously, instead of sequentially as in previous missions. This has cut the time from concept to the awarding of today's design and development contract from about five years to little more than one year. The design and development phase will take under four years, compared with up to six previously. Mars Express is making maximum use of pre-existing technology, which is either "off-the-shelf" or has already been developed for the Rosetta mission (also due for launch

  13. Green light for deployment of ESA's Mars Express radar

    NASA Astrophysics Data System (ADS)

    2005-02-01

    ESA's decision to deploy MARSIS follows eight months of intensive computer simulations and technical investigations on both sides of the Atlantic. These were to assess possible harmful boom configurations during deployment and to determine any effects on the spacecraft and its scientific instruments. The three radar booms of MARSIS were initially to have been deployed in April 2004, towards the end of the Mars Express instrument commissioning phase. They consist of a pair of 20-metre hollow cylinders, each 2.5 centimetres in diameter, and a 7-metre boom. No satisfactory ground test of deployment in flight conditions was possible, so that verification of the booms' performance had to rely on computer simulation. Just prior to their scheduled release, improved computer simulations carried out by the manufacturer, Astro Aerospace (California), revealed the possibility of a whiplash effect before they locked in their final outstretched positions, so that they might hit the spacecraft. Following advice from NASA’s Jet Propulsion Laboratory (JPL), which contributed the boom system to the Italian-led MARSIS radar instrument, and the Mars Express science team, ESA put an immediate hold on deployment until a complete understanding of the dynamics was obtained. JPL led a comprehensive investigation, including simulations, theoretical studies and tests on representative booms, the latter to assess potential aging of the boom material. European experts, from ESA and the former spacecraft prime contractor, Astrium SAS, France, worked closely with JPL throughout the entire investigation. An independent engineering review board, composed of ESA and industry experts, met in January to evaluate the findings and advise on ‘if and when’ to proceed with deployment. The ESA review board, at its final meeting on 25 January, recommended deployment of the MARSIS booms. The rationale for the decision was based on the results of the analyses, which showed the possible impact scenarios

  14. Multiphonon infrared absorption in silicon

    NASA Astrophysics Data System (ADS)

    Pradhan, M. M.; Garg, R. K.; Arora, M.

    1987-01-01

    Investigations have been carried out on silicon crystals, grown by float zone (FZ) and Czochralski (CZ) methods, of infrared absorption bands using a Fourier transform infrared spectrophotometer. Multiphonon bands are identified in the light of recent theoretical calculations based on the total energy of silicon crystal lattice. Theoretical results of Ihm et al. (1) and Yin and Cohen (2,3) are found to be in good agreement with the experimental observations of multiphonon infrared bands.

  15. The ESA Scientific Exploitation of Operational Missions element

    NASA Astrophysics Data System (ADS)

    Desnos, Yves-Louis; Regner, Peter; Delwart, Steven; Benveniste, Jerome; Engdahl, Marcus; Zehner, Claus; Mathieu, Pierre-Philippe; Bojkov, Bojan; Gascon, Ferran; Donlon, Craig; Davidson, Malcolm; Goryl, Philippe; Pinnock, Simon

    2015-04-01

    SEOM is a program element within the fourth period (2013-2017) of ESA's Earth Observation Envelope Programme (http://seom.esa.int/). The prime objective is to federate, support and expand the international research community that the ERS,ENVISAT and the Envelope programmes have built up over the last 25 years. It aims to further strengthen the leadership of the European Earth Observation research community by enabling them to extensively exploit future European operational EO missions. SEOM will enable the science community to address new scientific research that are opened by free and open access to data from operational EO missions. Based on community-wide recommendations for actions on key research issues, gathered through a series of international thematic workshops and scientific user consultation meetings, a work plan has been established and is approved every year by ESA Members States. The 2015 SEOM work plan is covering the organisation of three Science users consultation workshops for Sentinel1/3/5P , the launch of new R&D studies for scientific exploitation of the Sentinels, the development of open-source multi-mission scientific toolboxes, the organisation of advanced international training courses, summer schools and educational materials, as well as activities for promoting the scientific use of EO data. The first SEOM projects have been tendered since 2013 including the development of Sentinel toolboxes, advanced INSAR algorithms for Sentinel-1 TOPS data exploitation, Improved Atmospheric Spectroscopic data-base (IAS), as well as grouped studies for Sentinel-1, -2, and -3 land and ocean applications and studies for exploiting the synergy between the Sentinels. The status and first results from these SEOM projects will be presented and an outlook for upcoming SEOM studies will be given.

  16. ESA takes part in Earth observation and space science experiments on board the Space Shuttle

    NASA Astrophysics Data System (ADS)

    1993-03-01

    interesting phenomena show up. The third European instrument, called MAS (Millimeter Wave Atmospheric Sounder) will be measuring the absorption spectra of water vapour and trace gases in the upper atmosphere. The measurement programme includes most notably ozone and chlorine monoxide, which plays an important role in the ozone cycle. MAS was developed under the responsibility of Dr. Gerd Hartmann of the Max-Planck- Institute fuer Aeronomy, Lindau, Germany. The complex space-to-ground communications links and the tools to control the instruments from the laboratories in Europe have been designed to be as flexible and user-friendly as possible. The series of Atlas missions is enabling ESA to gain valuable experience for the future utilisation of its Columbus Attached Laboratory; its science results are at the same time a contribution to today's advances in space science and environmental research, complementing a number of dedicated ESA satellites currently under development, such as SOHO, ERS-2 and ENVISAT-1. Note to Editors : At the invitation of the Belgian Minister for Science Policy a press conference will be held on 22 March 1993 at 16.00 hours at the Belgian Royal Meteorological Institute in Brussels (IRMB). The press conference will be followed by the inauguration of the Space Remote Operations Centre, from where the telescience operations for the ATLAS-2 mission will be carried out. Apart from the Minister, those participating will include: Dirk Frimout, Belgian astronaut and ESA staff member Dominique Crommelynck, IRMB, Principal Investigator for SOLCON Gerard Thuillier, CNRS France, Principal Investigator for SOLSPEC Further information can be obtained from the Belgian Science Policy Office, Mrs. M.C. Limbourg or Mr. J. Bernard : Tel : +32.2.238.34.11 - Fax : +32.2.230.59.12

  17. ESA on the trail of the earliest stars

    NASA Astrophysics Data System (ADS)

    2003-01-01

    hi-res Size hi-res: 3054 kb Credits: NASA Simulated image of the distant Universe as seen by JWST This is a simulated image showing the abilities of the NGST. Compared to the Hubble Space Telescope the NGST will improve our 'sight' considerably. Artist's impression of JWST hi-res Size hi-res: 3960 kb Credits: ESA Artist's impression of JWST Image shows an artist's impression of the selected design for the JWST spacecraft. Northrop Grumman and Ball Aerospace are the prime contractors for JWST. Gamma-ray burst as seen by Integral Credits: ESA. Original image by the Integral IBIS team. Image processing by ESA/ECF Gamma-ray burst as seen by Integral A gamma-ray burst seen by ESA's Integral satellite. This picture was taken using the Imager on Board the Integral Satellite (IBIS). Astronomers suspect that some gamma-ray bursts are the explosions of individual population III stars. Astronomers know they must have been out there: only in this way could they solve the riddle of the origin and composition of stars in today's Universe. A couple of ESA missions will help astronomers search for this elusive population. When the Universe formed, there was just hydrogen and helium. Chemical elements such as oxygen, carbon, iron and so on were forged later, in the nuclear furnaces at the hearts of stars and then cast into space at the end of the star's life. Astronomers call everything that is heavier than helium a 'metal'. All stars we can observe today contain metals. The youngest contain the most metals and astronomers call them population I stars. The oldest contain only some metals and astronomers call these population II stars. Where do these metals come from? Astronomers have theorised that a first generation of stars, which they call population III, must have existed in the early Universe. This first generation of stars must have formed using only hydrogen and helium, the only elements available in the early cosmic history. After living for 'just' a million years, they

  18. The first Spacelab payload - A joint NASA/ESA venture

    NASA Technical Reports Server (NTRS)

    Kennedy, R.; Pace, R.; Collet, J.; Sanfourche, J. P.

    1977-01-01

    Planning for the 1980 qualification flight of Spacelab, which will involve a long module and one pallet, is discussed. The mission will employ two payload specialists, one sponsored by NASA and the other by ESA. Management of the Spacelab mission functions, including definition and execution of the on-board experiments, development of the experimental hardware and training of the payload specialists, is considered; studies proposed in the areas of atmospheric physics, space plasma physics, solar physics, earth observations, astronomy, astrophysics, life sciences and material sciences are reviewed. Analyses of the Spacelab environment and the Spacelab-to-orbiter and Spacelab-to-experiment interactions are also planned.

  19. NASA/ESA CV-990 Spacelab Simulation (ASSESS 2)

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Cost effective techniques for addressing management and operational activities on Spacelab were identified and analyzed during a ten day NASA-ESA cooperative mission with payload and flight responsibilities handled by the organization assigned for early Spacelabs. Topics discussed include: (1) management concepts and interface relationships; (2) experiment selection; (3) hardware development; (4) payload integration and checkout; (5) selection and training of mission specialists and payload specialists; (6) mission control center/payload operations control center interactions with ground and flight problems; (7) real time interaction during flight between principal investigators and the mission specialist/payload specialist flight crew; and (8) retrieval of scientific data and its analysis.

  20. "Europe lands on Mars" - Media event at ESA/ESOC

    NASA Astrophysics Data System (ADS)

    2003-11-01

    Launched on 2 June 2003 from Baikonur (Kazakhstan) on board a Russian Soyuz operated by Starsem, the European probe - built for ESA by a European team of industrial companies led by Astrium - carries seven scientific instruments that will perform a series of remote-sensing experiments designed to shed new light on the Martian atmosphere, the planet's structure and its geology. In particular, the British-made Beagle 2 lander will contribute to the search for traces of life on Mars through exobiology experiments and geochemistry research. On board Mars Express tests have been run to check that the instruments are functioning correctly. Mars Express has successfully come through its first power test on the whole spacecraft after the gigantic solar flare on 28 October. Since 17 November the onboard software has been 'frozen' after several updates and the spacecraft is now quietly proceeding to its destination. Before even entering into Martian orbit to perform its mission, Mars Express has to face another challenge: safely delivering the Beagle 2 lander to its destination. This task, starting on 19 December, will not be without risk. First of all, to deliver the lander where planned, Mars Express has been put on a collision course with Mars, since Beagle 2 does not have a propulsion system of its own and must therefore be 'carried' precisely to its destination. This means that after separation, Mars Express has to veer away quickly to avoid crashing onto the planet. During the cruise Beagle 2 will take its power from the mother spacecraft, Mars Express. After separation and until its solar arrays are fully deployed on the surface, Beagle 2 must rely on its own battery, which cannot last beyond 6 days. So, like a caring parent, Mars Express must release Beagle 2 at the last possible moment to ensure that the lander has enough power for the rest of its journey to the surface. Only then can Mars Express change its orientation and rapidly fire the thrusters to get away

  1. The Operations Security Concept for Future ESA Earth Observation Missions

    NASA Astrophysics Data System (ADS)

    Fischer, D.; Bargellini, P.; Merri, M.

    2008-08-01

    Next-generation European earth observation missions will play a critical role in public safety and security infrastructures. This makes it necessary for ESA to protect the communication infrastructure of these missions in order to guarantee their service availability. In this paper, we discuss the development process for a generic earth observation security concept. This concept has been developed as part of a GMES Flight Operation Segment security study with the objective to analyse and select a number of high level security requirements for the missions. Further, we studied the impact of an implementation for these requirements on the operational infrastructure of current earth observation missions.

  2. Mission to the Moon: An ESA study on future exploration

    NASA Technical Reports Server (NTRS)

    Chicarro, A. F.

    1993-01-01

    The increasing worldwide interest in the continuation of lunar exploration has convinced ESA to carry out an investigation of the motivations to return to the Moon to establish a permanent or a semi-permanent manned lunar base. This study also considers the possible role Europe could play in the future exploration and possible utilization of the Moon. The study concentrated in this first phase mainly on scientific questions, leaving technological issues such as transportation, the role of humans, infrastructure, and policy matters to a later phase. It only partially considered questions relating to the exploitation of lunar resources and the impact of human activities on science.

  3. MAJIS, the Moons And Jupiter Imaging Spectrometer, designed for the future ESA/JUICE mission

    NASA Astrophysics Data System (ADS)

    Piccioni, Giuseppe; Langevin, Yves; Filacchione, Gianrico; Poulet, Francois; Tosi, Federico; Eng, Pascal; Dumesnil, Cydalise; Zambelli, Massimo; Saggin, Bortolino; Fonti, Sergio; Grassi, Davide; Altieri, Francesca

    2014-05-01

    The Moons And Jupiter Imaging Spectrometer (MAJIS) is the VIS-IR spectral mapper selected for JUICE (Jupiter Icy Moon Explorer), the first Large-class mission in the ESA Cosmic Vision Programme. Scheduled for a launch in 2022, JUICE will perform a comprehensive exploration of the Jovian system thanks to several flybys of Callisto, Ganymede and Europa, before finally entering orbit around Ganymede. During these phases, MAJIS will acquire hyperspectral data necessary to unveil and map the surface composition of different geologic units of the satellites. Transfers between successive satellites' flybys shall be devoted to remote observations of Jupiter's atmosphere and auroras. MAJIS' instrument design relies on a 75 mm pupil, f/3.2 aperture TMA telescope matching two Czerny-Turner imaging spectrometers. A dichroic element is used to split the beam between the two spectral channels. The VIS-NIR spectral channel covers the 0.4-1.9 μm range with a sampling of 2.3 nm/band. The IR channel works in the 1.5-5.7 μm range with a 6.6 nm/band sampling. The entire optical structure is passively cooled at cryogenic temperature

  4. Status of the ESA L1 mission candidate ATHENA

    NASA Astrophysics Data System (ADS)

    Rando, N.; Martin, D.; Lumb, D.; Verhoeve, P.; Oosterbroek, T.; Bavdaz, M.; Fransen, S.; Linder, M.; Peyrou-Lauga, R.; Voirin, T.; Braghin, M.; Mangunsong, S.; van Pelt, M.; Wille, E.

    2012-09-01

    ATHENA (Advanced Telescope for High Energy Astrophysics) was an L class mission candidate within the science programme Cosmic Vision 2015-2025 of the European Space Agency, with a planned launch by 2022. ATHENA was conceived as an ESA-led project, open to the possibility of focused contributions from JAXA and NASA. By allowing astrophysical observations between 100 eV and 10 keV, it would represent the new generation X-ray observatory, following the XMM-Newton, Astro-H and Chandra heritage. The main scientific objectives of ATHENA include the study of large scale structures, the evolution of black holes, strong gravity effects, neutron star structure as well as investigations into dark matter. The ATHENA mission concept would be based on focal length of 12m achieved via a rigid metering tube and a twoaperture, x-ray telescope. Two identical x-ray mirrors would illuminate fixed focal plane instruments: a cryogenic imaging spectrometer (XMS) and a wide field imager (WFI). The S/C is designed to be fully compatible with Ariane 5 ECA. The observatory would operate at SE-L2, with a nominal lifetime of 5 yr. This paper provides a summary of the reformulation activities, completed in December 2011. An overview of the spacecraft design and of the payload is provided, including both telescope and instruments. Following the ESA Science Programme Committee decision on the L1 mission in May 2012, ATHENA was not selected to enter Definition Phase.

  5. Evaluating ESA CCI soil moisture in East Africa

    NASA Astrophysics Data System (ADS)

    McNally, Amy; Shukla, Shraddhanand; Arsenault, Kristi R.; Wang, Shugong; Peters-Lidard, Christa D.; Verdin, James P.

    2016-06-01

    To assess growing season conditions where ground based observations are limited or unavailable, food security and agricultural drought monitoring analysts rely on publicly available remotely sensed rainfall and vegetation greenness. There are also remotely sensed soil moisture observations from missions like the European Space Agency (ESA), Soil Moisture and Ocean Salinity (SMOS) and NASA's Soil Moisture Active Passive (SMAP); however, these time series are still too short to conduct studies that demonstrate the utility of these data for operational applications, or to provide historical context for extreme wet or dry events. To promote the use of remotely sensed soil moisture in agricultural drought and food security monitoring, we evaluate the quality of a 30+ year time series of merged active-passive microwave soil moisture from the ESA Climate Change Initiative (CCI-SM) over East Africa. Compared to the Normalized Difference Vegetation index (NDVI) and modeled soil moisture products, we find substantial spatial and temporal gaps in the early part of the CCI-SM record, with adequate data coverage beginning in 1992. From this point forward, growing season CCI-SM anomalies are well correlated (R > 0.5) with modeled soil moisture, and in some regions, NDVI. We use pixel-wise correlation analysis and qualitative comparisons of seasonal maps and time series to show that remotely sensed soil moisture can inform remote drought monitoring that has traditionally relied on rainfall and NDVI in moderately vegetated regions.

  6. Design and performance of the ESA Optical Ground Station

    NASA Astrophysics Data System (ADS)

    Reyes Garcia-Talavera, Marcos; Rodriguez, Jose A.; Viera, Teodora; Moreno-Arce, Heidi; Rasilla, Jose L.; Gago, Fernando; Rodriguez, Luis F.; Gomez, Panchita; Ballesteros Ramirez, Ezequiel

    2002-04-01

    The European Space Agency (ESA) has undertaken the development of Optical Data Relay payloads, aimed at establishing free space optical communication links between satellites. The first of such systems put into orbit is the SILEX project, in which an experimental link between a GEO satellite (ARTEMIS) and a LEO satellite (SPOT IV) will be used to relay earth observation data. In order to perform In Orbit Testing (IOT) of these and future optical communications systems, ESA and the Instituto de Astrofisica de Canarias (IAC) reached an agreement for the building of the Optical Ground Station (OGS) in the IAC Teide Observatory, which consists basically of a 1-meter telescope and the suitable instrumentation for establishing and testing bi-directional optical links with satellites. The presence of the atmosphere in the data path posses particular problems, with an impact on the instrumentation design. The transmission, reception and measurement functions, along with the overall control of the instruments, are performed at OGS by the Focal Plane Control Electronics (FPCE). The design and performance of this instrumentation is presented, emphasizing the Pointing, Acquisition and Tracking, the Tuneable Laser and the Master Control.

  7. ESA strategy for human exploration and the Lunar Lander Mission

    NASA Astrophysics Data System (ADS)

    Gardini, B.

    As part of ESAs Aurora Exploration programme, the Agency has defined, since 2001, a road map for exploration in which, alongside robotic exploration missions, the International Space Station (ISS) and the Moon play an essential role on the way to other destinations in the Solar System, ultimately to a human mission to Mars in a more distant future. In the frame of the Human Spaceflight programme the first European Lunar Lander Mission, with a launch date on 2018, has been defined, targeting the lunar South Pole region to capitalize on unique illumination conditions and provide the opportunity to carry out scientific investigations in a region of the Moon not explored so far. The Phase B1 industrial study, recently initiated, will consolidate the mission design and prepare the ground for the approval of the full mission development phase at the 2012 ESA Council at Ministerial. This paper describes the mission options which have been investigated in the past Phase A studies and presents the main activities foreseen in the Phase B1 to consolidate the mission design, including a robust bread-boards and technology development programme. In addition, the approach to overcoming the mission's major technical and environmental challenges and the activities to advance the definition of the payload elements will be described.

  8. The ESA SMART-1 Mission to the Moon: Goals and Science

    NASA Astrophysics Data System (ADS)

    Foing, B. H.; Racca, G. R.; SMART-1 Science and Technology Working Team

    2000-10-01

    SMART-1 is the first in the programme of ESA's Small Missions for Advanced Research and Technology . Its objective is to demonstrate Solar Electric Primary Propulsion (SEP) for future Cornerstones (such as Bepi-Colombo) and to test new technologies for spacecraft and instruments. The project aims to have the spacecraft ready in October 2002 for launch as an Ariane-5 auxiliary payload. After a cruise with primary SEP, the SMART-1 mission is to orbit the Moon for a nominal period of six months, with possible extension. The spacecraft will carry out a complete programme of scientific observations during the cruise and in lunar orbit. SMART-1's science payload, with a total mass of some 15 kg, features many innovative instruments and advanced technologies. A miniaturised high-resolution camera (AMIE) for lunar surface imaging, a near-infrared point-spectrometer (SIR) for lunar mineralogy investigation, and a very compact X-ray spectrometer (D-CIXS) with a new type of detector and micro-collimator which will provide fluorescence spectroscopy and imagery of the Moon's surface elemental composition. The payload also includes an experiment (KaTE) aimed at demonstrating deep-space telemetry and telecommand communications in the X and Ka-bands, a radio-science experiment (RSIS), a deep space optical link (Laser-Link Experiment), using the ESA Optical Ground station in Tenerife, and the validation of a system of autonomous navigation SMART-1 lunar science investigations include studies of the chemical (OBAN) based on image processing. SMART-1 lunar science investigations include studies of the chemica composition and evolution of the Moon, of geophysical processes (volcanism, tectonics, cratering, erosion, deposition of ices and volatiles) for comparative planetology, and high resolution studies in preparation for future steps of lunar exploration. The mission could address several topics such as the accretional processes that led to the formation of planets, and the origin

  9. NASA's Deep Space Network and ESA's Tracking Network Collaboration to Enable Solar System Exploration

    NASA Astrophysics Data System (ADS)

    Asmar, Sami; Accomazzo, Andrea; Firre, Daniel; Ferri, Paolo; Liebrecht, Phil; Mann, Greg; Morse, Gary; Costrell, Jim; Kurtik, Susan; Hell, Wolfgang; Warhaut, Manfred

    2016-07-01

    Planetary missions travel vast distances in the solar system to explore and answer important scientific questions. To return the data containing their discoveries, communications challenges have to be overcome, namely the relatively low transmitter power, typically 20 Watts at X-band, and the one-over-the-square of the distance loss of the received power, among other factors. These missions were enabled only when leading space agencies developed very large communications antennas to communicate with them as well as provide radio-metric navigation tools. NASA's Deep Space Network (DSN) and ESA's ESTRACK network are distributed geographically in order to provide global coverage and utilize stations ranging in size from 34 m to 70 m in diameter. With the increasing number of missions and significant loading on networks' capacity, unique requirements during critical events, and long-baseline interferometry navigation techniques, it became obvious that collaboration between the networks was necessary and in the interest of both agencies and the advancement of planetary and space sciences. NASA and ESA established methods for collaboration that include a generic cross-support agreement as well as mission-specific memoranda of understanding. This collaboration also led to the development of international inter-operability standards. As a result of its success, the DSN-ESTRACK cross support approach is serving as a model for other agencies with similar stations and an interest in collaboration. Over recent years, many critical events were supported and some scientific breakthroughs in planetary science were enabled. This paper will review selected examples of the science resulting from this work and the overall benefits for deep space exploration, including lessons learned, from inter-agency collaboration with communications networks.

  10. CERN, ESA and ESO Launch "Physics On Stage"

    NASA Astrophysics Data System (ADS)

    2000-03-01

    Physics is everywhere . The laws of physics govern the Universe, the Sun, the Earth and even our own lives. In today's rapidly developing society, we are becoming increasingly dependent on high technology - computers, transport, and communication are just some of the key areas that are the result of discoveries by scientists working in physics. But how much do the citizens of Europe really know about physics? Here is a unique opportunity to learn more about this elusive subject! [Go to Physics On Stage Website] Beginning in February 2000, three major European research organisations are organising a unique Europe-wide programme to raise the public awareness of physics and related sciences. "Physics on Stage" is launched by the European Laboratory for Particle Physics (CERN) , the European Space Agency (ESA) and the European Southern Observatory (ESO) , with support from the European Union. Other partners are the European Physical Society (EPS) and the European Association for Astronomy Education (EAAE). This exciting programme is part of the European Week for Science and Technology and will culminate in a Science Festival during November 6-11, 2000, on the CERN premises at the French-Swiss border near Geneva. Why "Physics on Stage"? The primary goal of "Physics on Stage" is to counteract the current decline in interest and knowledge about physics among Europe's citizens by means of a series of highly visible promotional activities. It will bring together leading scientists and educators, government bodies and the media, to confront the diminishing attraction of physics to young people and to develop strategies to reverse this trend. The objective in the short term is to infuse excitement and to provide new educational materials. In the longer term, "Physics on Stage" will generate new developments by enabling experts throughout Europe to meet, exchange and innovate. "Physics on Stage" in 22 European Countries "Physics on Stage" has been initiated in 22 European

  11. ESA `Huygens and Mars Express' science highlights - call to press

    NASA Astrophysics Data System (ADS)

    2005-11-01

    Almost one year has passed since ESA’s Huygens probe landed on Saturn’s largest moon, Titan. Today, a set of new wide-ranging results from the probe’s two-and-a-half hour descent and landing, part of the extraordinary NASA/ESA/ASI Cassini-Huygens mission to Saturn and its moons, is ready for release. At the same time, ESA’s Mars Express mission is continuing its investigations of Mars, painting a new picture of the 'red planet'. This includes the first ever probing below the surface of Mars, new geological clues with implications for the climate, newly-discovered surface and atmospheric features and, above all, traces of the presence of water on this world. These and other exciting findings from just one year of observations and data analysis - in the context of ESA’s overall scientific achievements - will be the focus of a press conference to be held at ESA Headquarters in Paris at 16:00 on 30 November 2005. Media interested in attending are invited to complete the following registration form. Press conference programme Space Science Highlights 2005 From Huygens to Mars Express 30 November 2005, 16:00 hrs Room 137, European Space Agency Headquarters 8-10 Rue Mario-Nikis, F-75738 Paris Cedex, France 15:30 - Registration 16:00 - A Year of European Space Science Successes Prof. David Southwood, ESA Director of Science Programme 16:10 - Highlights of the Huygens Mission Results Jean-Pierre Lebreton, ESA Huygens Project Scientist 16:15 - Robin Duttaroy, Co-Investigator, Doppler Wind Experiment, University of Bonn, Germany 16:20 - Marcello Fulchignoni , Principal Investigator, Huygens Atmospheric Structure Instrument, Université de Paris 7, France 16:25 - John Zarnecki, Principal Investigator, Surface Science Package, Open University, UK 16:30 - François Raulin, Co-Investigator, Gas Chromatograph Mass Spectrometer, Université de Paris 12 - Créteil, France 16:35 - Guy Israel, Principal Investigator, Aerosol Collector and Pyrolyser, Service d

  12. Bold ideas shortlisted for future ESA science projects

    NASA Astrophysics Data System (ADS)

    2000-03-01

    ESA's science programme introduced flexi-missions in 1997, to achieve greater flexibility. They replace the medium-scale projects, of which Huygens (Titan lander) and Integral (gamma-ray astronomy) are current examples. The aim is to have two flexi-missions for the price of one medium mission. Mars Express, already under construction for launch in 2003, is the first flexi-mission, or F1. Now under consideration are F2 and F3, each with a cost to ESA of no more than 176 million euros at 1999 prices. The frontrunner in the astronomy field for one of these slots is European participation with NASA in the Next Generation Space Telescope, successor to the NASA-ESA Hubble Space Telescope. Although a formal decision will not be taken until later this year, much European effort has already gone into preparing for this NGST project, due for launch in 2008. That intensifies the competition for the other slot. An embarrassment of riches - of ideas Multinational teams of scientists from Europe's universities and research institutes are backing each of the proposals selected for assessment, half of which concern the Solar System and the Earth's space environment. STORMS is a scheme to use three spacecraft to investigate a source of big trouble for technological systems, after solar eruptions. The "ring current" of energetic charged particles circulates around the equator at altitudes of several times the Earth's radius, and when its intensity varies during solar storms it causes magnetic perturbations at the Earth's surface. Three identical spacecraft, orbiting out to 50,000 kilometres and equally spaced around the equator, could clear up several remaining mysteries of the ring current -- and also provide real-time monitoring of magnetic storms. SOLAR ORBITER would fly on an extended orbit taking it at intervals to within about 30 million kilometres of the Sun -- much closer than the innermost planet, Mercury. At its closest approach the spacecraft would round the Sun at

  13. Visible absorption spectrum of liquid ethylene

    PubMed Central

    Nelson, Edward T.; Patel, C. Kumar N.

    1981-01-01

    The visible absorption spectrum of liquid ethylene at ≈ 108 K from 5500 Å to 7200 Å was measured by using a pulsed tunable dye laser, immersed-transducer, gated-detection opto-acoustic spectroscopy technique. The absorption features show the strongest band with an absorption coefficient of ≈2 × 10-2 cm-1 and the weakest band with an absorption coefficient of ≈1 × 10-4 cm-1. Proposed assignments of the observed absorption peaks involve combinations of overtones of local and normal modes of vibration of ethylene. PMID:16592978

  14. ESA's experts are ready for a storm of comet dust

    NASA Astrophysics Data System (ADS)

    1998-11-01

    Minute grains of dust create the glowing heads and tails that make comets famous. A trail of dust traces the orbit of each comet, and when the Earth encounters a comet trail the result is a meteor shower. Comet Tempel-Tuttle has just refreshed its dust trail on a visit to the Sun's vicinity, which it makes every 33 years. The Leonids approach the Earth from the direction of the constellation Leo. As a precaution, the Hubble Space Telescope will turn its back on Leo for ten hours around the predicted peak of the Leonid event, which is at about 20:30 CET on 17 November. Astronomers will take the opportunity to look for undiscovered galaxies in the opposite direction in the sky. Any disturbances caused to the 11.6-tonne Hubble spacecraft by the Leonid dust impacts will be recorded for analysis by dust specialists. One of the teams chosen for this study includes ESA and UK scientists and is headed by John Zarnecki of the University of Kent. Zarnecki comments: "It seems like doing an experiment with the crown jewels. But Hubble is a fantastically accurate star pointer, so we should detect wobbles due to quite small impacts. We hope to check our theories about the numbers of grains of different masses. But I'd hate to see any harm come to Hubble," Zarnecki adds. "Or any other spacecraft for that matter." Taking account of the risk to spacecraft This year Comet Tempel-Tuttle passed within 1.2 million kilometres of the Earth's orbit, which is very near by astronomical standards. Similar close encounters have produced widely differing results in the past. In 1932 the count of visible meteors in the Leonids reached an unremarkable rate of 240 per hour, compared with a normal background of about 10-20 sporadic meteors per hour at quiet times. Yet in 1966 the count-rate for the Leonids was 15,000 per hour, or 4 per second, and some observers reported even higher rates. If the rate is again 15,000 per hour, a spacecraft presenting a target of 10 square metres to the Leonid

  15. An ESA precursor mission to human exploration of the Moon

    NASA Astrophysics Data System (ADS)

    Carpenter, James; Fisackerly, Richard; Houdou, Berengere; Pradier, Alain; de Rossa, Diego; Vanoutryve, Benjamin; Jojaghaian, Aliac; Espinasse, Sylvie; Gardini, Bruno

    2010-05-01

    The coming decades will once again see humans on the surface of the Moon. Unlike the Apollo missions of the 1960s this new lunar exploration will be an international effort, with long duration missions and a goal to pave the way for further human expansion into the solar system. Ensuring the success and sustainability of this exploration poses significant challenges for all involved. ESA is currently preparing its first contribution to this international lunar exploration effort; a lunar lander mission, which will be a precursor to a future, Ariane V launched, ESA cargo and logistics capability to the Moon. The precursor mission will demonstrate soft precision landing with hazard avoidance capabilities, which will be required by a future cargo lander. In addition the mission can be applied as a preparation for future human exploration activities and help to ensure the sustainability of future exploration efforts. Activities have included Phase A and B1 mission design studies and technology development activities (both reported in another paper) and the definition of mission objectives and a model payload. The mission objectives have been derived by the Lunar Exploration Definition Team, a group derived of European specialists in various areas of exploration related science and technology, supported by ESA. Major inputs to the definition process were the 195 responses received to a request for information for potential payload contributions to the mission. The group was tasked with establishing how such a mission could best prepare for future human exploration. It was determined that the mission's goal should be to enable sustainable exploration and objectives were identified within a number of themes: health, habitation, resources, mobility and scientific preparations for future human activities. Investigations seek to characterise the lunar environment (e.g. radiation, dust etc.) and its effects and the properties of a landing site (potential resources, geological

  16. An ESA precursor mission to human exploration of the Moon

    NASA Astrophysics Data System (ADS)

    Carpenter, James; Fisackerly, Richard; Houdou, Berengere; Pradier, Alain; de Rossa, Diego; Vanoutryve, Benjamine; Jojaghaian, Aliac; Espinasse, Sylvie; Gardini, Bruno

    The coming decades will once again see humans on the surface of the Moon. Unlike the Apollo missions of the 1960s this new lunar exploration will be an international effort, with long duration missions and a goal to pave the way for further human expansion into the solar system. Ensuring the success and sustainability of this exploration poses significant challenges for all involved. ESA is currently preparing its first contribution to this international lunar exploration effort; a lunar lander mission, which will be a precursor to a future, Ariane V launched, ESA cargo and logistics capability to the Moon. The precursor mission will demonstrate soft precision landing with hazard avoidance capabilities, which will be required by a future cargo lander. In addition the mission can be applied as a preparation for future human exploration activities and help to ensure the sustainability of future exploration efforts. Activities have included Phase A and B1 mission design studies and technology development activities (both reported in another paper) and the definition of mission objectives and a model payload. The mission objectives have been derived by the Lunar Exploration Definition Team, a group derived of European specialists in various areas of exploration related science and technology, supported by ESA. Major inputs to the definition process were the 195 responses received to a request for information for potential payload contributions to the mission. The group was tasked with establishing how such a mission could best prepare for future human exploration. It was determined that the mission's goal should be to enable sustainable exploration and objectives were identified within a number of themes: health, habitation, resources, mobility and scientific preparations for future human activities. Investigations seek to characterise the lunar environment (e.g. radiation, dust etc.) and its effects and the properties of a landing site (potential resources, geological

  17. The ESA Nanosatellite Beacons for Space Weather Monitoring Study

    NASA Astrophysics Data System (ADS)

    Hapgood, M.; Eckersley, S.; Lundin, R.; Kluge, M.

    2008-09-01

    This paper will present final results from this ESA-funded study that has investigated how current and emerging concepts for nanosats may be used to monitor space weather conditions and provide improved access to data needed for space weather services. The study has reviewed requirements developed in previous ESA space weather studies to establish a set of service and measurements requirements appropriate to nanosat solutions. The output is conveniently represented as a set of five distinct classes of nanosat constellations, each in different orbit locations and which can address a specific group of measurement requirements. One example driving requirement for several of the constellations was the need for real-time data reception. Given this background, the study then iterated a set of instrument and spacecraft solutions to address each of the nanosat constellations from the requirements. Indeed, iteration has proved to be a critical aspect of the study. The instrument solutions have driven a refinement of requirements through assessment of whether or not the physical parameters to be measured dictate instrument components too large for a nanosat. In addition, the study has also reviewed miniaturization trends for instruments relevant to space weather monitoring by nanosats, looking at the near, mid and far-term timescales. Within the spacecraft solutions the study reviewed key technology trends relevant to space weather monitoring by nanosats: (a) micro and nano-technology devices for spacecraft communications, navigation, propulsion and power, and (b) development and flight experience with nanosats for science and for engineering demonstration. These requirements and solutions were then subject to an iterative system and mission analysis including key mission design issues (e.g. launch/transfer, mission geometry, instrument accommodation, numbers of spacecraft, communications architectures, de-orbit, nanosat reliability and constellation robustness) and the

  18. Overview of the knowledge management system in ESA/ESOC

    NASA Astrophysics Data System (ADS)

    Dow, Roberta Mugellesi; Pallaschke, Siegmar; Merri, Mario; Montagnon, Elsa; Schabe, Melanie; Belingheri, Maurizio; Bucher, Michael

    2008-07-01

    This paper discusses the knowledge management (KM) system as implemented in a pilot project at the European Space Operations Centre (ESOC) of the European Space Agency (ESA). By means of audits, we have identified the main knowledge fields in our domain, weighted their importance in the short, medium and long terms, and derived KM requirements in order to preserve, maintain, share and enhance relevant knowledge. The preliminary results from the knowledge audits were analysed and discussed by domain experts, showing that the KM process put in place has been successfully validated and appropriate measures, like continuous training, have to be put in place. The KM requirements were then mapped on the existing KM infrastructure and the available KM resources in order to assess the status of KM at ESOC and to recommend its evolution. Finally, some additional suggestions are made regarding the future of the initiative and potential steps that might be taken to further support KM within ESOC.

  19. THOR - a mission candidate for ESA M4

    NASA Astrophysics Data System (ADS)

    Vaivads, Andris

    2015-04-01

    We present a mission concept THOR (http://thor.irfu.se) that was proposed in the response to the ESA M4 Call. The scientific theme of the THOR mission is turbulent energy dissipation and particle energization. The main focus is on turbulence and shock processes, however areas where the different fundamental processes interact, such as reconnection in turbulence or shock generated turbulence, is also of high importance. The THOR mission aims to address such fundamental questions as how energy is dissipated at kinetic scales, how energy is partitioned among different plasma components, what is the relative importance of waves and coherent structures in the dissipation processes. To reach the goal a careful design work of the THOR mission and its payload has been done and it is based on the earlier mission concepts of Tor, EIDOSCOPE and Cross-Scale. We present the basic concepts of the THOR mission, THOR's payload and the major science questions to be addressed.

  20. The ESA Meteoroid Model 2010: Enhanced Physical Model

    NASA Astrophysics Data System (ADS)

    Dikarev, Valeri; Mints, Alexey; Drolshagen, Gerhard

    The orbital distributions of meteoroids in interplanetary space are revised in the ESA meteoroid model. In the present update, the chemical composition of the meteoroids is simulated in more detail than in the previous meteoroid models. Silicate and carbonaceous fractions are introduced for all meteoroid populations, and in addition to asteroids and Jupiter-crossing comets, comet 2P/Encke is added as a source. The orbital evolution under planetary gravity, Poynting-Robertson effect and mutual collisions is simulated using analytical approximations. Infrared observations of the zodiacal cloud by the COBE DIRBE instrument, in situ flux measurements by the dust detectors on board Galileo, Ulysses, Pioneer 11 and Helios-1 spacecraft, and the crater size distributions on lunar rock samples retrieved by the Apollo missions are incorporated in the model.

  1. Results from the Survey of ESA Science Archives

    NASA Astrophysics Data System (ADS)

    Arviset, C.; Baines, D.; Osuna, P.

    2013-10-01

    Most of ESA's Space Science Archives are currently hosted at ESAC, the European Space Astronomy Centre, located near Madrid, Spain. All these science archives are designed, developed, operated and maintained by a dedicated Science Archives and VO Team, providing support to all science operations centres at ESAC. At the end of 2011, a questionnaire was sent to all users of the ESAC Science Archives in the last five years, asking them about their usage frequency, their satisfaction level, the type of interfaces used (GUI or scriptable interface or others) and the purpose for which they are using the archives. The survey also allowed optionally to provide qualitative feedback. This paper presents the main results from this questionnaire, from a global perspective of all the archives.

  2. ESA New Generation Science Archives: SOHO and EXOSAT

    NASA Astrophysics Data System (ADS)

    Osuna, P.; Arviset, C.; Baines, D.; Barbarisi, I.; Castellanos, J.; Cheek, N.; Costa, H.; Fajersztejn, N.; Fernandez, M.; Gonzalez, J.; Laruelo, A.; Leon, I.; Ortiz, I.; Salgado, J.; Stebe, A.; Tapiador, D.

    2010-12-01

    The ESAC Science Archives and VO Team (SAT) has developed a new infrastructure for the development and maintenance of the ESA space based missions’ Science Archives. This infrastructure makes use of state-of-the-art technology to overcome some of the already known limitations of older technologies, used for the building of the current archives, the older of which has been live since 1998. This paper describes how the SAT approached the issue of re-engineering their infrastructure to result in a more flexible, reusable, robust and cost-effective way of building their archives. It also describes how the new technology has been applied to the building of two Science Archive s from scratch: the SOHO Science Archive (a Solar physics mission) and the EXOSAT Science Archive (an astronomy mission).

  3. SOHO Mission Interruption Joint NASA/ESA Investigation Board

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Contact with the SOlar Heliospheric Observatory (SOHO) spacecraft was lost in the early morning hours of June 25, 1998, Eastern Daylight Time (EDT), during a planned period of calibrations, maneuvers, and spacecraft reconfigurations. Prior to this the SOHO operations team had concluded two years of extremely successful science operations. A joint European Space Agency (ESA)/National Aeronautics and Space Administration (NASA) engineering team has been planning and executing recovery efforts since loss of contact with some success to date. ESA and NASA management established the SOHO Mission Interruption Joint Investigation Board to determine the actual or probable cause(s) of the SOHO spacecraft mishap. The Board has concluded that there were no anomalies on-board the SOHO spacecraft but that a number of ground errors led to the major loss of attitude experienced by the spacecraft. The Board finds that the loss of the SOHO spacecraft was a direct result of operational errors, a failure to adequately monitor spacecraft status, and an erroneous decision which disabled part of the on-board autonomous failure detection. Further, following the occurrence of the emergency situation, the Board finds that insufficient time was taken by the operations team to fully assess the spacecraft status prior to initiating recovery operations. The Board discovered that a number of factors contributed to the circumstances that allowed the direct causes to occur. The Board strongly recommends that the two Agencies proceed immediately with a comprehensive review of SOHO operations addressing issues in the ground procedures, procedure implementation, management structure and process, and ground systems. This review process should be completed and process improvements initiated prior to the resumption of SOHO normal operations.

  4. ESA's Planetary Science Archive: International collaborations towards transparent data access

    NASA Astrophysics Data System (ADS)

    Heather, David

    The European Space Agency's (ESA) Planetary Science Archive (PSA) is the central repository for science data returned by all ESA planetary missions. Current holdings include data from Giotto, SMART-1, Cassini-Huygens, Mars Express, Venus Express, and Rosetta. In addition to the basic management and distribution of these data to the community through our own interfaces, ESA has been working very closely with international partners to globalize the archiving standards used and the access to our data. Part of this ongoing effort is channelled through our participation in the International Planetary Data Alliance (IPDA), whose focus is on allowing transparent and interoperable access to data holdings from participating Agencies around the globe. One major focus of this work has been the development of the Planetary Data Access Protocol (PDAP) that will allow for the interoperability of archives and sharing of data. This is already used for transparent access to data from Venus Express, and ESA are currently working with ISRO and NASA to provide interoperable access to ISRO's Chandrayaan-1 data through our systems using this protocol. Close interactions are ongoing with NASA's Planetary Data System as the standards used for planetary data archiving evolve, and two of our upcoming missions are to be the first to implement the new 'PDS4' standards in ESA: BepiColombo and ExoMars. Projects have been established within the IPDA framework to guide these implementations to try and ensure interoperability and maximise the usability of the data by the community. BepiColombo and ExoMars are both international missions, in collaboration with JAXA and IKI respectively, and a strong focus has been placed on close interaction and collaboration throughout the development of each archive. For both of these missions there is a requirement to share data between the Agencies prior to public access, as well as providing complete open access globally once the proprietary periods have

  5. Bold ideas shortlisted for future ESA science projects

    NASA Astrophysics Data System (ADS)

    2000-03-01

    ESA's science programme introduced flexi-missions in 1997, to achieve greater flexibility. They replace the medium-scale projects, of which Huygens (Titan lander) and Integral (gamma-ray astronomy) are current examples. The aim is to have two flexi-missions for the price of one medium mission. Mars Express, already under construction for launch in 2003, is the first flexi-mission, or F1. Now under consideration are F2 and F3, each with a cost to ESA of no more than 176 million euros at 1999 prices. The frontrunner in the astronomy field for one of these slots is European participation with NASA in the Next Generation Space Telescope, successor to the NASA-ESA Hubble Space Telescope. Although a formal decision will not be taken until later this year, much European effort has already gone into preparing for this NGST project, due for launch in 2008. That intensifies the competition for the other slot. An embarrassment of riches - of ideas Multinational teams of scientists from Europe's universities and research institutes are backing each of the proposals selected for assessment, half of which concern the Solar System and the Earth's space environment. STORMS is a scheme to use three spacecraft to investigate a source of big trouble for technological systems, after solar eruptions. The "ring current" of energetic charged particles circulates around the equator at altitudes of several times the Earth's radius, and when its intensity varies during solar storms it causes magnetic perturbations at the Earth's surface. Three identical spacecraft, orbiting out to 50,000 kilometres and equally spaced around the equator, could clear up several remaining mysteries of the ring current -- and also provide real-time monitoring of magnetic storms. SOLAR ORBITER would fly on an extended orbit taking it at intervals to within about 30 million kilometres of the Sun -- much closer than the innermost planet, Mercury. At its closest approach the spacecraft would round the Sun at

  6. 40 CFR 796.1050 - Absorption in aqueous solution: Ultraviolet/visible spectra.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... by both molar absorption coefficient (molar extinction coefficient) and band width. However, the..., expressed in cm; and the molar absorption (extinction) coefficient,εi, of each species. The...

  7. 40 CFR 796.1050 - Absorption in aqueous solution: Ultraviolet/visible spectra.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... by both molar absorption coefficient (molar extinction coefficient) and band width. However, the..., expressed in cm; and the molar absorption (extinction) coefficient,εi, of each species. The...

  8. 40 CFR 796.1050 - Absorption in aqueous solution: Ultraviolet/visible spectra.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... by both molar absorption coefficient (molar extinction coefficient) and band width. However, the..., expressed in cm; and the molar absorption (extinction) coefficient,εi, of each species. The...

  9. 40 CFR 796.1050 - Absorption in aqueous solution: Ultraviolet/visible spectra.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... by both molar absorption coefficient (molar extinction coefficient) and band width. However, the..., expressed in cm; and the molar absorption (extinction) coefficient,εi, of each species. The...

  10. 40 CFR 796.1050 - Absorption in aqueous solution: Ultraviolet/visible spectra.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... by both molar absorption coefficient (molar extinction coefficient) and band width. However, the..., expressed in cm; and the molar absorption (extinction) coefficient,εi, of each species. The...

  11. Gastric Banding

    MedlinePlus

    ... gastric banding before deciding to have the procedure. Advertisements for a device or procedure may not include ... feeds Follow FDA on Twitter Follow FDA on Facebook View FDA videos on YouTube View FDA photos ...

  12. Directed evolution of the quorum-sensing regulator EsaR for increased signal sensitivity.

    PubMed

    Shong, Jasmine; Huang, Yao-Ming; Bystroff, Christopher; Collins, Cynthia H

    2013-04-19

    The use of cell-cell communication or "quorum sensing (QS)" elements from Gram-negative Proteobacteria has enabled synthetic biologists to begin engineering systems composed of multiple interacting organisms. However, additional tools are necessary if we are to progress toward synthetic microbial consortia that exhibit more complex, dynamic behaviors. EsaR from Pantoea stewartii subsp. stewartii is a QS regulator that binds to DNA as an apoprotein and releases the DNA when it binds to its cognate signal molecule, 3-oxohexanoyl-homoserine lactone (3OC6HSL). In the absence of 3OC6HSL, EsaR binds to DNA and can act as either an activator or a repressor of transcription. Gene expression from P(esaR), which is repressed by wild-type EsaR, requires 100- to 1000-fold higher concentrations of signal than commonly used QS activators, such as LuxR and LasR. Here we have identified EsaR variants with increased sensitivity to 3OC6HSL using directed evolution and a dual ON/OFF screening strategy. Although we targeted EsaR-dependent derepression of P(esaR), our EsaR variants also showed increased 3OC6HSL sensitivity at a second promoter, P(esaS), which is activated by EsaR in the absence of 3OC6HSL. Here, the increase in AHL sensitivity led to gene expression being turned off at lower concentrations of 3OC6HSL. Overall, we have increased the signal sensitivity of EsaR more than 70-fold and generated a set of EsaR variants that recognize 3OC6HSL concentrations ranging over 4 orders of magnitude. QS-dependent transcriptional regulators that bind to DNA and are active in the absence of a QS signal represent a new set of tools for engineering cell-cell communication-dependent gene expression. PMID:23363022

  13. Definition of the oxygen A-band channels of ENVISAT's Medium Resolution Imaging Spectrometer for cloud monitoring

    NASA Astrophysics Data System (ADS)

    Kollewe, M.; Fischer, Juergen

    1994-12-01

    During the `European Lidar Airborne Campaign' in 1990 the backscattered sunlight in the region of the O2 A-band at 0.76 micrometers was measured above various clouds. The multispectral radiance measurements were performed with a nadir-looking device with a spectral resolution of (Delta) (lambda) equals 0.42 nm. A `Principal Component Analysis' was applied to about 140000 spectra, each consisting of 320 channels. It turns out that above clouds with optical depths (delta) c > 10 or above clouds over oceans three spectral regions with (Delta) (lambda) approximately equals 2.5 - 5 nm contain the entire information of the high- resolved spectra. One of these intervals is located near the absorption band (window channel) while the remaining two cover the R- and the P-branch of the O2 A-band, respectively. Based on this finding, the O2 A-band channels of the planned `Medium Resolution Imaging Spectrometer' (MERIS, ESA), dedicated to the detection of the cloud-top height, are defined.

  14. ESA joins forces with Japan on new infrared sky surveyor

    NASA Astrophysics Data System (ADS)

    2006-02-01

    analysis. This second phase will end with the depletion of the liquid helium needed to cool down the spacecraft telescope and its instruments to only a few degrees above absolute zero. ASTRO-F will then start its third operations phase and continue to make observations of selected celestial targets with its infrared camera only, in a few specific infrared wavelengths. ESA’s involvement: Only two decades have passed since the birth of space-based infrared astronomy; since then, each decade has been marked by the launch of innovative infrared satellites that have revolutionised our very perception of the cosmos. In fact, infrared satellites make possible the detection of cool objects, including planetary systems, interstellar dust and gas, or distant galaxies, all of which are most difficult to study in the visible part of the light spectrum. With infrared astronomy, it is also possible to study the birth of stars and galaxies, the ‘creation’ energy of which peaks in the infrared range. The European Space Agency and Europe have a strong tradition in infrared astronomy, which is now being continued by the participation of the UK, the Netherlands and ESA in ASTRO-F. ESA is providing network support through its ground station in Kiruna (Sweden) for a few passes per day. ESA is also providing expertise and support for the sky-survey data processing. This includes ‘pointing reconstruction’ - which means measuring exactly where the observed objects are in the sky, to help accelerate the production of sky catalogues and ultimately produce a census of the infrared universe. In return, ESA has obtained ten percent of the observing opportunities during the second and third operational phases of the ASTRO-F mission, which is being allocated to European astronomers to perform their proposed observations. “The cooperation offered to ESA by Japan in ASTRO-F will help keep up momentum for European astronomers as they build on their past work with ISO, and look forward to the

  15. Thermodynamic derivatives of infrared absorptance

    NASA Technical Reports Server (NTRS)

    Broersma, S.; Walls, W. L.

    1974-01-01

    Calculation of the concentration, pressure, and temperature dependence of the spectral absorptance of a vibrational absorption band. A smooth thermodynamic dependence was found for wavelength intervals where the average absorptance is less than 0.65. Individual rotational lines, whose parameters are often well known, were used as bases in the calculation of medium resolution spectra. Two modes of calculation were combined: well-separated rotational lines plus interaction terms, or strongly overlapping lines that were represented by a compound line of similar shape plus corrections. The 1.9- and 6.3-micron bands of H2O and the 4.3-micron band of CO2 were examined in detail and compared with experiment.

  16. Band Model Calculations for CFCl3 in the 8-12 micron Region

    NASA Technical Reports Server (NTRS)

    Silvaggio, Peter M.; Boese, Robert W.; Nanes, Roger

    1980-01-01

    A Goody random band model with a Voigt line profile is used to calculate the band absorption of CFCB at various pressures at room and stratospheric (216 K) temperatures. Absorption coefficients and line spacings are computed.

  17. Cholesterol absorption.

    PubMed

    Ostlund, Richard E

    2002-03-01

    Cholesterol absorption is a key regulatory point in human lipid metabolism because it determines the amount of endogenous biliary as well as dietary cholesterol that is retained, thereby influencing whole body cholesterol balance. Plant sterols (phytosterols) and the drug ezetimibe reduce cholesterol absorption and low-density lipoprotein cholesterol in clinical trials, complementing the statin drugs, which inhibit cholesterol biosynthesis. The mechanism of cholesterol absorption is not completely known but involves the genes ABC1, ABCG5, and ABCG8, which are members of the ATP-binding cassette protein family and appear to remove unwanted cholesterol and phytosterols from the enterocyte. ABC1 is upregulated by the liver X (LXR) and retinoid X (RXR) nuclear receptors. Acylcholesterol acytransferase-2 is an intestinal enzyme that esterifies absorbed cholesterol and increases cholesterol absorption when dietary intake is high. New clinical treatments based on better understanding of absorption physiology are likely to substantially improve clinical cholesterol management in the future. PMID:17033296

  18. In-situ Observations of Space Debris at ESA

    NASA Astrophysics Data System (ADS)

    Drolshagen, G.

    Information on the small size (millimetre or smaller) space debris and meteoroid population in space can only be obtained by in-situ detectors or the analysis of retrieved hardware. Past, ongoing and planned ESA activities in this field are presented. In 1996 the GORID impact detector was launched into a geostationary orbit on-board the Russian Express-2 telecommunication satellite. This impact ionisation detector had a sensor surface of 0.1 m2. Until July 2002 when the spacecraft was shut down it recorded more than 3000 impacts in the micrometre size range. Inter alia, GORID measured numerous clusters of events, believed to result from debris clouds, and indicated that debris fluxes in GEO are larger than predicted by present models. Another in-situ detector, DEBIE-1, was launched in October 2001 and is operating on-board the small technology satellite PROBA in a low polar orbit. It has two sensors, each of 0.01m2 size, pointing in different directions. A second detector of this type, DEBIE-2 with 3 sensors, is ready for flight on the EuTEF carrier (external payload to ISS). The data from GORID and DEBIE-1 are stored on-line in EDID (European Detector Impact Database). Post-flight impact analyses of retrieved hardware provide detailed information on the encountered meteoroid and debris fluxes over a large range of sizes. ESA initiated several analyses in the past ((EURECA, Hubble Space Telescope (HST) solar arrays). The most recent impact analysis was performed for the HST solar arrays retrieved in March 2002. Measured crater sizes in solar cells ranged from about 1 micron to 7 mm. A total of 175 complete penetrations of the 0.7 mm thick arrays were observed. A chemical analysis of impact residues allowed the distinction between space debris and natural meteoroids. Space debris was found to dominate for sizes smaller than 10 microns and larger than about 1 mm. For intermediate sizes impacts are mainly from meteoroids. Results of the analysis and comparisons with

  19. THE JOINT ESA-NASA EUROPA JUPITER SYSTEM MISSION (EJSM)

    NASA Astrophysics Data System (ADS)

    Lebreton, J.; Pappalardo, R. T.; Blanc, M.; Bunce, E. J.; Dougherty, M. K.; Erd, C.; Grasset, O.; Greeley, R.; Johnson, T. V.; Clark, K. B.; Prockter, L. M.; Senske, D. A.

    2009-12-01

    The joint "Europa Jupiter System Mission" (EJSM) is an international mission under study in collaboration between NASA and ESA. Its goal is to study Jupiter and its magnetosphere, the diversity of the Galilean satellites, the physical characteristics, composition and geology of their surfaces. Europa and Ganymede are two primary targets of the mission. The reference mission architecture consists of the NASA-led Jupiter Europa Orbiter (JEO) and the ESA-led Jupiter Ganymede Orbiter (JGO). The two primary goals of the mission are i) to determine whether the Jupiter system harbors habitable worlds and ii) to characterize the processes within the Jupiter system. The science objectives addressing the first goal are to: i) characterize and determine the extent of subsurface oceans and their relations to the deeper interior, ii) characterize the ice shells and any subsurface water, including the heterogeneity of the ice, and the nature of surface-ice-ocean exchange; iii) characterize the deep internal structure, differentiation history, and (for Ganymede) the intrinsic magnetic field; iv) compare the exospheres, plasma environments, and magnetospheric interactions; v) determine global surface composition and chemistry, especially as related to habitability; vi) understand the formation of surface features, including sites of recent or current activity, and identify and characterize candidate sites for future in situ exploration. The science objectives for addressing the second goal are to: i) understand the Jovian satellite system, especially as context for Europa and Ganymede; ii) evaluate the structure and dynamics of the Jovian atmosphere; iii) characterize processes of the Jovian magnetodisk/magnetosphere; iv) determine the interactions occurring in the Jovian system; and v) constrain models for the origin of the Jupiter system. Both spacecraft would carry a complement of 11-12 instruments launch separately in 2020 and use a Venus-Earth-Earth Gravity Assist (VEEGA

  20. Status of the ESA Meteosat Second Generation (MSG) Programme

    NASA Astrophysics Data System (ADS)

    Stark, H. R.; Schumann, W.

    2004-11-01

    Following on from the first generation of Meteosat, the Meteosat Second Generation (MSG) programme promises to provide advanced and more frequent data for short-range and medium-range weather forecasting and climate monitoring for at least the next 12 years. The MSG programme is a cooperation between ESA and EUMETSAT, the European Organisation for the Exploitation of Meteorological Satellites organisation. ESA has been responsible for designing and developing the first of the four satellites in the MSG programme, whilst EUMETSAT has overall responsibility for defining the end-user requirements, developing the ground segment and operating the system. The first MSG satellite, called MSG-1 (METEOSAT 8), was successfully launched on 28August 2002 by an Ariane 5 launcher together with its co-passenger Atlantic Bird. ESOC took over control of the satellite after separation and placed the satellite from the Ariane injection orbit to a quasi-geostationary orbit drifting slowly towards the commissioning longitude at 10.5 deg West. Subsequently EUMETSAT started the satellite commissioning testing. Except the in-orbit failure of an on-board amplifier, with its consequences for the dissemination service, the achieved results show a high degree of compliance with respect to the satellite specification and show very good overall performance of the satellite, in particular for the Spinning Enhanced Visible and Infrared Imager (SEVIRI) instrument to be outstanding. METEOSAT-8 entered routine operations on 29 January 2004. In parallel with the MSG-1 commissioning activities, the integration and test phases on the other MSG satellites has well progressed. Begin March 2004, EUMETSAT took the decision to take the MSG-2 satellite out of storage, resuming testing and work on it towards its final preparation for launch with a launch period now defined between February and April 2005. MSG-3 is entered into storage in summer this year. It is an intermediate storage configuration, after the

  1. ESA's Integral detects closest cosmic gamma-ray burst

    NASA Astrophysics Data System (ADS)

    2004-08-01

    5 August 2004 A gamma-ray burst detected by ESA's Integral gamma-ray observatory on 3 December 2003 has been thoroughly studied for months by an armada of space and ground-based observatories. Astronomers have now concluded that this event, called GRB 031203, is the closest cosmic gamma-ray burst on record, but also the faintest. This also suggests that an entire population of sub-energetic gamma-ray bursts has so far gone unnoticed... Gamma ray burst model hi-res Size hi-res: 22 KB Credits: CXC/M. Weiss Artist impression of a low-energy gamma-ray burst This illustration describes a model for a gamma-ray burst, like the one detected by Integral on 3 December 2003 (GRB 031203). A jet of high-energy particles from a rapidly rotating black hole interacts with surrounding matter. Observations with Integral on 3 December 2003 and data on its afterglow, collected afterwards with XMM-Newton, Chandra and the Very Large Array telescope, show that GRB 031203 radiated only a fraction of the energy of normal gamma-ray bursts. Like supernovae, gamma-ray bursts are thought to be produced by the collapse of the core of a massive star. However, while the process leading to supernovae is relatively well understood, astronomers still do not know what happens when a core collapses to form a black hole. The discovery of 'under-energetic' gamma-ray bursts, like GRB 031203, should provide valuable clues as to links between supernovae, black holes and gamma-ray bursts. Lo-res JPG (22 Kb) Hi-res TIFF (5800 Kb) Cosmic gamma-ray bursts (GRBs) are flashes of gamma rays that can last from less than a second to a few minutes and occur at random positions in the sky. A large fraction of them is thought to result when a black hole is created from a dying star in a distant galaxy. Astronomers believe that a hot disc surrounding the black hole, made of gas and matter falling onto it, somehow emits an energetic beam parallel to the axis of rotation. According to the simplest picture, all GRBs

  2. Earth Observation Training and Education with ESA LearnEO!

    NASA Astrophysics Data System (ADS)

    Byfield, Valborg; Mathieu, Pierre-Philippe; Dobson, Malcolm; Rosmorduc, Vinca; Del Frate, Fabio; Banks, Chris; Picchiani, Matteo

    2013-04-01

    For society to benefit fully from its investment in Earth observation, EO data must be accessible and familiar to a global community of users who have the skills, knowledge and understanding to use the observations appropriately in their work. Achieving this requires considerable education effort. LearnEO! (www.learn-eo.org) is a new ESA education project that contributes towards making this a reality. LearnEO! has two main aims: to develop new training resources that use data from sensors on ESA satellites to explore a variety of environmental topics, and to stimulate and support members of the EO and education communities who may be willing to develop and share new education resources in the future. The project builds on the UNESCO Bilko project, which currently supplies free software, tutorials, and example data to users in 175 countries. Most of these users are in academic education or research, but the training resources are also of interest to a growing number of professionals in government, NGOs and private enterprise. Typical users are not remote sensing experts, but see satellite data as one of many observational tools. They want an easy, low-cost means to process, display and analyse data from different satellite sensors as part of their work in environmental research, monitoring and policy development. Many of the software improvements and training materials developed in LearnEO! are in response to requests from this user community. The LearnEO! tutorial and peer-reviewed lessons are designed to teach satellite data processing and analysis skills at different levels, from beginner to advanced - where advanced lessons requires some previous experience with Earth observation techniques. The materials are aimed at students and professionals in various branches of Earth sciences who have not yet specialised in specific EO technologies. The lessons are suitable for self-study, university courses at undergraduate to MSc level, or for continued professional

  3. A preliminary optical design for the JANUS camera of ESA's space mission JUICE

    NASA Astrophysics Data System (ADS)

    Greggio, D.; Magrin, D.; Ragazzoni, R.; Munari, M.; Cremonese, G.; Bergomi, M.; Dima, M.; Farinato, J.; Marafatto, L.; Viotto, V.; Debei, S.; Della Corte, V.; Palumbo, P.; Hoffmann, H.; Jaumann, R.; Michaelis, H.; Schmitz, N.; Schipani, P.; Lara, L.

    2014-08-01

    The JANUS (Jovis, Amorum ac Natorum Undique Scrutator) will be the on board camera of the ESA JUICE satellite dedicated to the study of Jupiter and its moons, in particular Ganymede and Europa. This optical channel will provide surface maps with plate scale of 15 microrad/pixel with both narrow and broad band filters in the spectral range between 0.35 and 1.05 micrometers over a Field of View 1.72 × 1.29 degrees2. The current optical design is based on TMA design, with on-axis pupil and off-axis field of view. The optical stop is located at the secondary mirror providing an effective collecting area of 7854 mm2 (100 mm entrance pupil diameter) and allowing a simple internal baffling for first order straylight rejection. The nominal optical performances are almost limited by the diffraction and assure a nominal MTF better than 63% all over the whole Field of View. We describe here the optical design of the camera adopted as baseline together with the trade-off that has led us to this solution.

  4. Influence of safety warnings on ESA prescribing among dialysis patients using an interrupted time series

    PubMed Central

    2013-01-01

    Background In March, 2007, a black box warning was issued by the Food and Drug Administration (FDA) to use the lowest possible erythropoiesis-stimulating agents (ESA) doses for treatment of anemia associated with renal disease. The goal is to determine if a change in ESA use was observed following the warning among US dialysis patients. Methods ESA therapy was examined from September 2004 through August 2009 (thirty months before and after the FDA black box warning) among adult Medicare hemodialysis patients. An interrupted time series model assessed the impact of the warnings. Results The FDA black box warning did not appear to influence ESA prescribing among the overall dialysis population. However, significant declines in ESA therapy after the FDA warnings were observed for selected populations. Patients with a hematocrit ≥36% had a declining month-to-month trend before (−164 units/week, p = <0.0001) and after the warnings (−80 units/week, p = .001), and a large drop in ESA level immediately after the black box (−4,744 units/week, p = <.0001). Not-for-profit facilities had a declining month-to-month trend before the warnings (−90 units/week, p = .009) and a large drop in ESA dose immediately afterwards (−2,487 units/week, p = 0.015). In contrast, for-profit facilities did not have a significant change in ESA prescribing. Conclusions ESA therapy had been both profitable for providers and controversial regarding benefits for nearly two decades. The extent to which a FDA black box warning highlighting important safety concerns influenced use of ESA therapy among nephrologists and dialysis providers was unknown. Our study found no evidence of changes in ESA prescribing for the overall dialysis population resulting from a FDA black box warning. PMID:23927675

  5. Operational Experience with Autonomous Star Trackers on ESA Interplanetary Spacecraft

    NASA Technical Reports Server (NTRS)

    Lauer, Mathias; Jauregui, Libe; Kielbassa, Sabine

    2007-01-01

    Mars Express (MEX), Rosetta and Venus Express (VEX) are ESA interplanetary spacecrafts (S/C) launched in June 2003, March 2004 and November 2005, respectively. Mars Express was injected into Mars orbit end of 2003 with routine operations starting in spring 2004. Rosetta is since launch on its way to rendezvous comet Churyumov-Gerasimenko in 2014. It has completed several test and commissioning activities and is performing several planetary swingbys (Earth in spring 2005, Mars in spring 2007, Earth in autumn 2007 and again two years later). Venus Express has also started routine operations since the completion of the Venus orbit insertion maneuver sequence beginning of May 2006. All three S/C are three axes stabilized with a similar attitude and orbit control system (AOCS). The attitude is estimated on board using star and rate sensors and controlled using four reaction wheels. A bipropellant reaction control system with 10N thrusters serves for wheel off loadings and attitude control in safe mode. Mars Express and Venus Express have an additional 400N engine for the planetary orbit insertion. Nominal Earth communication is accomplished through a high gain antenna. All three S/C are equipped with a redundant set of autonomous star trackers (STR) which are based on almost the same hardware. The STR software is especially adapted for the respective mission. This paper addresses several topics related to the experience gained with the STR operations on board the three S/C so far.

  6. Research recommendations of the ESA Topical Team on Artificial Gravity

    NASA Astrophysics Data System (ADS)

    Clément, Gilles; Bukley, Angie

    Many experts believe that artificial gravity will be required for an interplanetary mission. However, despite its attractiveness as an efficient, multi-system countermeasure and its potential for simplifying operational activities, much still needs to be learned regarding the human response to rotating environments before artificial gravity can be successfully implemented. The European Space Agency (ESA) Topical Team on Artificial Gravity recommended a comprehensive program to determine the gravity threshold required to reverse or prevent the detrimental effects of microgravity and to evaluate the effects of centrifugation on various physiological functions. Part of the required research can be accomplished using animal models on a dedicated centrifuge in low Earth orbit. Studies of human responses to centrifugation could be performed during ambulatory, short- and long-duration bed rest, and in-flight studies. Artificial-gravity scenarios should not be a priori discarded in Moon and Mars mission designs. One major step is to determine the relationship between the artificial gravity dose level, duration, and frequency and the physiological responses of the major body functions affected by spaceflight. Once its regime characteristics are defined and a dose-response curve is established, artificial gravity should serve as the standard against which all other countermeasure candidates are evaluated, first on Earth and then in space.

  7. The Possibility of GRB Investigations by ESA Satellite Gaia

    NASA Astrophysics Data System (ADS)

    Hudec, R.; Hudec, L.

    2011-08-01

    We refer on further studies on possibility to investigate the Optical Afterglows and Optical Transients of GRBs by the ESA satellite Gaia to be launched in 2012, The satellite will focus on highly precise astrometry of stars and all objects down to limiting magnitude 20. Albeit focusing on astrometry related matters, the satellite will also provide photometric and spectral information and hence important inputs for various branches of astrophysics. Within the Gaia Variability Unit CU7 and related work package Specific Object Studies there has been a sub-work package accepted for optical counterparts to celestial high-energy sources, a category which includes the optical counterparts (i.e. optical transients and optical afterglows, including counterparts of XRFs and yet hypothetical orphan afterglows) of GRBs. Although the sampling of photometric data will not be optimal for this type of work, the strength of Gaia in such analyses is the fine spectral resolution (spectro-photometry) which will allow the correct classification of related triggers. The possibilities to detect and to analyze optical transients and optical afterglows of GRBs by Gaia will be presented and discussed.

  8. The ESA Rad-Hard electron monitor (RADEM) for JUICE

    NASA Astrophysics Data System (ADS)

    Desorgher, Laurent; Hajdas, Wojtek; Goncalves, Patricia; Pinto, Costa; Marques, Arlindo; Chastellain, Frédéric; Gambarara, Fabio; Muff, Reto; Maehlum, Gunnar; Meier, Dirk

    2014-05-01

    The ESA Jupiter Icy moons explorer (JUICE) mission will encounter a harsh radiation environment that is known to be severe but that is not yet fully understood. The Rad-Hard electron monitor (RADEM), currently under development, is a compact instrument (1L, 1kg, 2.2W) that will be set on JUICE for measuring the radiation environment during the mission. Its design is adapted to the harsh Jovian radiation environment and optimized for the detection of high energetic electrons. RADEM will consist of three detector subunits. The magneto-spectrometer will measure the electron spectrum in the 0.3 to 40 MeV range. The directionality sensor will characterize the pitch angle distribution of the electron environment. The Silicon stack detector will be dedicated to measure the spectrum of solar and Jovian protons, as well as the LET spectrum of heavy ions. In this paper we present the status of the development of RADEM, as well as Geant4 Monte Carlo analysis of the capability of the instruments.

  9. Particle Environment Package (PEP) for the ESA JUICE mission

    NASA Astrophysics Data System (ADS)

    Barabash, Stas; Wurz, Peter; PEP Team

    2013-04-01

    Particle Environment Package (PEP) is a suite of particle sensors proposed for the ESA JUICE mission. PEP includes sensors for the comprehensive measurements of electrons, ions, energetic neutrals, and neutral gas. PEP covers over nine decades of energy <0.001 eV to >1 MeV with full angular coverage. Combining remote global imaging via energetic neutral atoms (ENAs) with in-situ measurements, PEP addresses all scientific objectives of the JUICE mission relevant to particle measurements. PEP will seek answers for four overarching science questions: How does the corotating magnetosphere of Jupiter interact with complex and diverse environment of Ganymede? How does the rapidly rotating magnetosphere of Jupiter interact with seemingly inert Callisto? What are the governing mechanisms and their global impact of release of material into the Jupiter magnetosphere from Europa and Io? How do internal and solar wind drivers cause such energetic, time variable and multi-scale phenomena in the steadily rotating giant magnetosphere of Jupiter? We discuss the suite's sensor basic design, performance, radiation mitigation principles and demonstrate how the suite fully addresses its scientific objectives.

  10. M⁴ - a mission candidate for ESA M4

    NASA Astrophysics Data System (ADS)

    Retino, A.; Vaivads, A.

    2014-12-01

    We present a mission concept that will be proposed in the response to the upcoming ESA M4 Call. The working name of the mission is M⁴. The scientific theme of the M⁴ mission is turbulent energy dissipation and particle energization. The main focus is on turbulence and shock processes, however areas where the different fundamental processes interact, such as reconnection in turbulence or shock generated turbulence, is also of high importance. The M⁴ mission aims to address such fundamental questions as how energy is dissipated at kinetic scales, how energy is partitioned among different plasma components, what is the relative importance of waves and coherent structures in the dissipation processes. To reach the goal a careful design work of the M⁴ mission and its payload has been done and it is based on the earlier mission concepts of Tor, EIDOSCOPE and Cross-Scale. We present the basic concepts of the M⁴ mission and its payload as well as illustrate how it will help to address the science questions posed.

  11. "Europe lands on Mars" - Media event at ESA/ESOC

    NASA Astrophysics Data System (ADS)

    2003-11-01

    Launched on 2 June 2003 from Baikonur (Kazakhstan) on board a Russian Soyuz operated by Starsem, the European probe - built for ESA by a European team of industrial companies led by Astrium - carries seven scientific instruments that will perform a series of remote-sensing experiments designed to shed new light on the Martian atmosphere, the planet's structure and its geology. In particular, the British-made Beagle 2 lander will contribute to the search for traces of life on Mars through exobiology experiments and geochemistry research. On board Mars Express tests have been run to check that the instruments are functioning correctly. Mars Express has successfully come through its first power test on the whole spacecraft after the gigantic solar flare on 28 October. Since 17 November the onboard software has been 'frozen' after several updates and the spacecraft is now quietly proceeding to its destination. Before even entering into Martian orbit to perform its mission, Mars Express has to face another challenge: safely delivering the Beagle 2 lander to its destination. This task, starting on 19 December, will not be without risk. First of all, to deliver the lander where planned, Mars Express has been put on a collision course with Mars, since Beagle 2 does not have a propulsion system of its own and must therefore be 'carried' precisely to its destination. This means that after separation, Mars Express has to veer away quickly to avoid crashing onto the planet. During the cruise Beagle 2 will take its power from the mother spacecraft, Mars Express. After separation and until its solar arrays are fully deployed on the surface, Beagle 2 must rely on its own battery, which cannot last beyond 6 days. So, like a caring parent, Mars Express must release Beagle 2 at the last possible moment to ensure that the lander has enough power for the rest of its journey to the surface. Only then can Mars Express change its orientation and rapidly fire the thrusters to get away

  12. ESA's new European Hubble Science Archive at ESAC

    NASA Astrophysics Data System (ADS)

    Baines, Deborah

    2015-12-01

    ESA's European Space Astronomy Centre (ESAC) has recently launched a new version of the European Hubble Space Telescope science archive. The new and enhanced archive offers several new features, some of which are not available anywhere else. The new web-based archive has been completely re-engineered and is now faster, more accurate and more robust than ever. Several of its unique features will be presented: the possibility of seeing the exact footprint of each observations on top of an optical all-sky image, the online visualization and inspection of FITS headers, imaging and spectral observation previews without downloading files or the possibility to search for data that has not yet been published in refereed journals. This state-of-the-art science data archive will be the new main access point to HST data for the European astronomical community and will be enhanced in the near-future to include the Hubble Source Catalogue or other high-level data products as required.

  13. A Statistical Look on ESA's Conjunction Event Predictions

    NASA Astrophysics Data System (ADS)

    Flohrer, T.; Krag, H.; Lemmens, S.; Bastida Virgili, B.; Merz, K.; Klinkrad, H.

    2013-08-01

    On a routine basis, ESA predicts close conjunctions for its own satellites and assesses the associated collision risk. This process is supported by acquiring external tracking data to improve the knowledge on orbit state and associated uncertainties of the secondary object, and by evaluating close approach notifications and conjunction summary messages received from the US Joint Space Operations Center (JSpOC). The process also includes screening of planned manoeuvres for close conjunctions. ESOC-operated missions in low Earth orbit and in highly-eccentric orbits are covered. Recently, the process has been extended to cover third party missions. We describe the applied process and present the latest status, including a history of high-risk conjunction events and processed CSMs, and we revisit major recent software developments. As this process has been in place for some years, we can use the archived results for a detailed assessment of the close conjunctions from an operator's perspective. We analyse the evolution of object classes and the accumulated risk from TLE-based information for secondary objects. The impact of the severe collision events in 2007 and 2009 is also part of this discussion.

  14. ESA hardware for plant research on the International Space Station

    NASA Astrophysics Data System (ADS)

    Brinckmann, E.

    The long awaited launch of the European Modular Cultivation System (EMCS) will provide a platform on which long-term and shorter experiments with plants will be performed on the International Space Station (ISS). EMCS is equipped with two centrifuge rotors (600 mm diameter), which can be used for in-flight 1 g controls and for studies with acceleration levels from 0.001 g to 2.0 g. Several experiments are in preparation investigating gravity relating to gene expression, gravisensing and phototropism of Arabidopsis thaliana and lentil roots. The experiment-specific hardware provides growth chambers for seedlings and whole A. thaliana plants and is connected to the EMCS Life Support System. Besides in-flight video observation, the experiments will be evaluated post-flight by means of fixed or frozen material. EMCS will have for the first time the possibility to fix samples on the rotating centrifuge, allowing a detailed analysis of the process of gravisensing. About two years after the EMCS launch, ESA's Biolab will be launched in the European "Columbus" Module. In a similar way as in EMCS, Biolab will accommodate experiments with plant seedlings and automatic fixation processes on the centrifuge. The hardware concepts for these experiments are presented in this communication.

  15. ESA sees stardust storms heading for Solar System

    NASA Astrophysics Data System (ADS)

    2003-08-01

    The Sun's galactic environment Credits: P.C. Frisch, University of Chicago The Sun's galactic environment The Sun and the nearest stars move through filaments of galactic clouds. Ulysses and the heliosphere hi-res Size hi-res: 1337 kb Credits: ESA (image by D. Hardy) Ulysses and the heliosphere Over more than 17 years of observations above and below the poles of the Sun, the ESA/NASA Ulysses mission has made fundamental contributions to our understanding of the Sun itself, its sphere of influence (the heliosphere), and our local interstellar neighbourhood. The mission provided the first-ever map of the heliosphere in the four dimensions of space and time. Ulysses was launched by Space Shuttle Discovery in October 1990. It headed out to Jupiter, arriving in February 1992 for the gravity-assist manoeuvre that swung the craft into its unique solar orbit. It orbited the Sun three times and performed six polar passes. The mission concludes on 1 July 2008. Since its launch in 1990, Ulysses has constantly monitored how much stardust enters the Solar System from the interstellar space around it. Using an on-board instrument called DUST, scientists have discovered that stardust can actually approach the Earth and other planets, but its flow is governed by the Sun's magnetic field, which behaves as a powerful gate-keeper bouncing most of it back. However, during solar maximum - a phase of intense activity inside the Sun that marks the end of each 11-year solar cycle - the magnetic field becomes disordered as its polarity reverses. As a result, the Sun's shielding power weakens and more stardust can sneak in. What is surprising in this new Ulysses discovery is that the amount of stardust has continued to increase even after the solar activity calmed down and the magnetic field resumed its ordered shape in 2001. Scientists believe that this is due to the way in which the polarity changed during solar maximum. Instead of reversing completely, flipping north to south, the Sun

  16. ESA scientist discovers a way to shortlist stars that might have planets

    NASA Astrophysics Data System (ADS)

    2002-02-01

    Traces of the disc surrounding our Solar System Credits: Michael Hauser (Space Telescope Science Institute), the COBE/DIRBE Science Team, and NASA Traces of the disc surrounding our Solar System Traces of the disc surrounding our Solar System. The blue band curving across this image is created by the dust disc surrounding our Solar System. Viewed from afar this would show up as a bright ring surrounding the Sun. The bright band running across the centre of the image is from dust in our Galaxy. This image, taken by the COBE satellite, is a composite of three far-infrared wavelengths (60, 100, and 240 microns). (Photo: Michael Hauser (Space Telescope Science Institute), the COBE/DIRBE Science Team, and NASA) Disc surrounding the Sun Credits: Brad Smith (University of Hawaii), Glenn Schneider (University of Arizona), and NASA Viewed from afar our Solar System would have a bright disc surrounding the Sun Viewed from afar our Solar System would have a bright dust disc surrounding the Sun similar to the disc surrounding this star. This image, taken with Hubble's Near Infrared Camera and Multi-Object Spectrometer (NICMOS), shows a dust ring around a star called HR 4796A. The image was taken on March 15, 1998. (Photo: Brad Smith (University of Hawaii), Glenn Schneider (University of Arizona), and NASA) Ulysses in flight configuration hi-res Size hi-res: 117 Kb Credits: ESA/Dave Hardy Ulysses at Jupiter encounter Ulysses in flight configuration passing by Jupiter. Remarkably, their discovery gives astronomers a way to determine which other stars in the Galaxy are most likely to harbour planets and allows mission planners to draw up a 'short-list' of stars to be observed by ESA's future planet-search missions, Eddington and Darwin. The discovery of the Solar System's dust ring strengthens the idea that such features around mature stars are signposts to planetary systems. The reason for this is that planetary systems are thought to condense from a cloud of gas and dust

  17. Public Speaking Instruction with the Experiential, Self-Empowerment Approach (ESA): An Ethnomethodological Look.

    ERIC Educational Resources Information Center

    Bedore, Joan M.

    This paper takes a ethnomethodological look at a typical Experiential Self-Empowerment Approach (ESA)-using speech class to see how the ESA uses 12 assumptions as background expectancies (Heritage, 1984) to accomplish personal growth in college public speaking classes. The following assumptions are addressed: (1) students deserve "something more"…

  18. “Will the real ESA please stand up?” [Column

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Entomological Society of America, the largest association of insect scientists in the world, is known by the acronym “ESA.” However, there are many other associations, agencies, companies, concepts and laws which share the ESA moniker. This eye-opening and humorous column sets out a few for th...

  19. Cost Considerations in Database Selection: A Comparison of DIALOG and ESA/IRS.

    ERIC Educational Resources Information Center

    Jack, Robert F.

    1984-01-01

    Of 25 databases available on both DIALOG and European Space Agency's Information Retrieval Service (ESA/IRS), five are less expensive on DIALOG by three price factors (online connect charges, online displays of citations, offline prints); five are less expensive on ESA/IRS; remaining 15 represent mixed bag (connect charges offset citation…

  20. Bundled-rate legislation for Medicare reimbursement for dialysis services: implications for anemia management with ESAs.

    PubMed

    Charytan, Chaim

    2010-12-01

    With the incidence of ESRD on the rise, there is a continuing need to control anemia-related treatment costs in dialysis patients receiving reimbursement through Medicare. Currently, erythropoiesis-stimulating agents (ESAs) are billed separately from dialysis services, potentially creating little financial incentive for more efficient use. The Medicare Improvement for Patients and Providers Act, passed by the U.S. Congress in July 2008, includes provisions intended to address this concern. Under this act, dialysis services will be reimbursed using a fully bundled, comprehensive payment system that includes all services currently covered in the basic composite rate, as well as certain separately billable items, including ESAs. A base rate of $229.63 per treatment has been assigned, to be individualized using case-mix adjusters. The implications of this new system for anemia management with ESAs continue to be elucidated. With fixed compensation for ESAs, management strategies that maximize efficiencies and, thereby, optimize cost savings will be favored. Select strategies may include switching from intravenous (IV) to subcutaneous routes, lowering Hb targets and ESA doses in hyporesponsive patients, increasing administration of IV iron, increasing use of home dialysis, and optimizing ESA dosing intervals. Once-monthly ESA therapy has potential advantages under this new system as an alternative to more frequently administered ESAs and may help achieve quality metrics in a cost-efficient manner. PMID:21071515

  1. ESA's Soil Moisture and Ocean Salinity Mission - An overview on the mission's performance and scientific results

    NASA Astrophysics Data System (ADS)

    Mecklenburg, Susanne

    2014-05-01

    , responding to the requirements of the science community in particular in the area of hydrology, climate, land use and ship routing, namely a frozen soil indicator, data products for freeze/thaw periods, sea ice thickness and vegetation water content. 3. Provide an update on the overall validation approach and recent activities: SMOS data products are continuously improved and approach the scientific mission objectives. Validation activities are essential to ensure high data quality. ESA in collaboration with national agencies and institutions maintains a frame for validation activities such as reference sites, ground based observations as well as campaigns. The paper will provide an update on recent activities, such as the activities at DOME-C. 4. Summarise the collaboration with other space-borne L-band sensors, such as NASA's Aquarius and SMAP missions.

  2. An analytic formula for heating due to ozone absorption

    NASA Technical Reports Server (NTRS)

    Lindzen, R. S.; Will, D. I.

    1972-01-01

    An attempt was made to devise a simple expression or formula to describe radiative heating in the atmosphere by ozone absorption. Such absorption occurs in the Hartley, Huggins, and Chappuis bands and is only slightly temperature and pressure dependent.

  3. ESA scientist discovers a way to shortlist stars that might have planets

    NASA Astrophysics Data System (ADS)

    2002-02-01

    Traces of the disc surrounding our Solar System Credits: Michael Hauser (Space Telescope Science Institute), the COBE/DIRBE Science Team, and NASA Traces of the disc surrounding our Solar System Traces of the disc surrounding our Solar System. The blue band curving across this image is created by the dust disc surrounding our Solar System. Viewed from afar this would show up as a bright ring surrounding the Sun. The bright band running across the centre of the image is from dust in our Galaxy. This image, taken by the COBE satellite, is a composite of three far-infrared wavelengths (60, 100, and 240 microns). (Photo: Michael Hauser (Space Telescope Science Institute), the COBE/DIRBE Science Team, and NASA) Disc surrounding the Sun Credits: Brad Smith (University of Hawaii), Glenn Schneider (University of Arizona), and NASA Viewed from afar our Solar System would have a bright disc surrounding the Sun Viewed from afar our Solar System would have a bright dust disc surrounding the Sun similar to the disc surrounding this star. This image, taken with Hubble's Near Infrared Camera and Multi-Object Spectrometer (NICMOS), shows a dust ring around a star called HR 4796A. The image was taken on March 15, 1998. (Photo: Brad Smith (University of Hawaii), Glenn Schneider (University of Arizona), and NASA) Ulysses in flight configuration hi-res Size hi-res: 117 Kb Credits: ESA/Dave Hardy Ulysses at Jupiter encounter Ulysses in flight configuration passing by Jupiter. Remarkably, their discovery gives astronomers a way to determine which other stars in the Galaxy are most likely to harbour planets and allows mission planners to draw up a 'short-list' of stars to be observed by ESA's future planet-search missions, Eddington and Darwin. The discovery of the Solar System's dust ring strengthens the idea that such features around mature stars are signposts to planetary systems. The reason for this is that planetary systems are thought to condense from a cloud of gas and dust

  4. Band Together!

    ERIC Educational Resources Information Center

    Olson, Cathy Applefeld

    2011-01-01

    After nearly a decade as band director at St. James High School in St. James, Missouri, Derek Limback knows that the key to building a successful program is putting the program itself above everything else. Limback strives to augment not only his students' musical prowess, but also their leadership skills. Key to his philosophy is instilling a…

  5. ESA chairs the International Living With a Star programme

    NASA Astrophysics Data System (ADS)

    2003-02-01

    The Sun is a variable star. The amount of radiation it releases changes constantly, especially at wavelengths that we cannot see, such as ultraviolet. It also releases a stormy ‘wind’ of particles known as the solar wind that buffets the Earth’s magnetic field. Sudden changes in the solar wind can disable communications satellites, disrupt power stations on Earth, and affect passengers in high-flying aircraft. Slow variation in the solar output and even in the solar wind could contribute to climatic changes. Knowing more about these phenomena is therefore very important in different and sometimes unexpected ways. There will be various ILWS mission launches over an approximately ten-year period, starting in 2003. Pooling the resources of the largest fleet of spacecraft in history, the ILWS programme will provide a first global view of the Sun-Earth interaction and lead to a real understanding of it. It will look at the Sun’s effects on other planets also. ESA’s missions form a vital part of ILWS. SOHO and Cluster are leading the way. In 2003, in collaboration with China, a space mission called Double Star will be launched to complement Cluster. In a decade’s time, ESA’s Solar Orbiter will be the centre of interest. It will go closer to the Sun than any solar mission ever before. In between, ESA will assist in exploiting other agency’s missions to the full; it is also currently negotiating to provide ground stations for Japan’s Solar-B mission (launch 2005), and is considering the part it may play in NASA’s STEREO (launch 2005) and Solar Dynamics Orbiter (launch 2007) missions. In addition, ESA’s missions to the other terrestrial planets, Mars Express (launching 2003), Venus Express (launching 2005), and the mission to Mercury, BepiColombo (launching 2011/2012), will carry experiments that look at solar-wind interactions with their respective planets. Hermann Opgenoorth, ESA’s newly appointed Head of Solar and Solar-Terrestrial Missions, is

  6. The 2009 ESA/Danish Mars Simulation Wind Tunnel Facility

    NASA Astrophysics Data System (ADS)

    Nornberg, P.; Merrison, J. P.; Gunnlaugsson, H. P.

    2009-04-01

    Simulation of the dynamic environment in immediate proximity to the surface of Mars requires access to simulation facilities which can reproduce the atmospheric properties (pressure, temperature, gas composition, UV-VIS light conditions, wind flow etc.). It also requires access to analogue Martian surface material (soil and dust). Simulations can be carried out in a wind tunnel placed in a tank which can be pumped out, like the 400 mm Ø, 1500 mm long wind tunnel that has operated in the Mars Simulation Laboratory at University of Aarhus, Denmark since 2000 (1). A wide range of applications have taken place, from development, test and calibration of instruments, over tests of solar panels, and aerodynamic studies of granular transport to studies of physical properties of dust materials such as grain electrification, aggregation and magnetic properties (2,3). The Salten Skov I analogue (4) and other Martian regolits and dust analogues have been used in the wind tunnel experiments. With the view to future instrument development, solar panel optimization and future research on Martian surface processes a new ESA supported wind tunnel has been constructed at University of Aarhus, Denmark and is now under building. This wind tunnel will have a cross section of close to 1 x 2 m and be able to reach a wind speed of close to 30 m/s under Martian pressure conditions and with samples cooled down to Martian temperatures. The facility is planned to be finally tested and ready for use in July 2009. ESA, ExoMars use of this facility will have priority. However, research projects in collaboration with external users will also be welcome in the future. Later this year information on access possibilities will be announced at the Mars Simulation Laboratory home page: www.marslab.dk. References: (1) Merrison, J., Bertelsen, P., Frandsen, C., Gunnlaugsson, H.P., Knudsen, J.M., Madsen, M.B., Mossin, L., Nielsen, J., Nørnberg, P., Rasmussen, K.R., Uggerhøj, E. and Weyer, G. 2002

  7. Rosetta performs ESA's closest-ever Earth fly-by

    NASA Astrophysics Data System (ADS)

    2005-03-01

    Rosetta’s unique instruments, such as its ultraviolet light instrument ALICE, should be able to make critical contributions to the American mission. About Rosetta Rosetta is the first mission designed to both orbit and land on a comet, and consists of an orbiter and a lander. The spacecraft carries 11 scientific experiments and will be the first mission to undertake long-term exploration of a comet at close quarters. After entering orbit around Comet 67P/Churyumov-Gerasimenko in 2014, the spacecraft will release a small lander onto the icy nucleus. Rosetta will orbit the comet for about a year as it heads towards the Sun, remaining in orbit for another half-year past perihelion (closest approach to the Sun). Comets hold essential information about the origin of our Solar System because they are the most primitive objects in the Solar System and their chemical composition has changed little since their formation. By orbiting and landing on Comet 67P/Churyumov-Gerasimenko, Rosetta will help us reconstruct the history of our own neighbourhood in space. Note for broadcasters: The ESA TV Service will transmit a TV exchange with images of the fly-by, together with science results/images from observations as far as available on 11 March. For further details : http://television.esa.int

  8. The ESA Lunar Lander and the search for Lunar Volatiles

    NASA Astrophysics Data System (ADS)

    Morse, A. D.; Barber, S. J.; Pillinger, J. M.; Sheridan, S.; Wright, I. P.; Gibson, E. K.; Merrifield, J. A.; Waltham, N. R.; Waugh, L. J.; Pillinger, C. T.

    2011-10-01

    Following the Apollo era the moon was considered a volatile poor body. Samples collected from the Apollo missions contained only ppm levels of water formed by the interaction of the solar wind with the lunar regolith [1]. However more recent orbiter observations have indicated that water may exist as water ice in cold polar regions buried within craters at concentrations of a few wt. % [2]. Infrared images from M3 on Chandrayaan-1 have been interpreted as showing the presence of hydrated surface minerals with the ongoing hydroxyl/water process feeding cold polar traps. This has been supported by observation of ephemeral features termed "space dew" [3]. Meanwhile laboratory studies indicate that water could be present in appreciable quantities in lunar rocks [4] and could also have a cometary source [5]. The presence of sufficient quantities of volatiles could provide a resource which would simplify logistics for long term lunar missions. The European Space Agency (ESA's Directorate of Human Spaceflight and Operations) have provisionally scheduled a robotic mission to demonstrate key technologies to enable later human exploration. Planned for launch in 2018, the primary aim is for precise automated landing, with hazard avoidance, in zones which are almost constantly illuminated (e.g. at the edge of the Shackleton crater at the lunar south pole). These regions would enable the solar powered Lander to survive for long periods > 6 months, but require accurate navigation to within 200m. Although landing in an illuminated area, these regions are close to permanently shadowed volatile rich regions and the analysis of volatiles is a major science objective of the mission. The straw man payload includes provision for a Lunar Volatile and Resources Analysis Package (LVRAP). The authors have been commissioned by ESA to conduct an evaluation of possible technologies to be included in L-VRAP which can be included within the Lander payload. Scientific aims are to demonstrate the

  9. EGSE (Electrical Ground Support Equipment) for ESA VEGA Launcher

    NASA Astrophysics Data System (ADS)

    Ferrante, M.; Ortenzi, A.; del Re, V.; Bordin, M.; Saccucci, Fr.

    2004-08-01

    Activities belonging to Assembly, Integration and Validation (AIV) phase of a launch vehicle are fundamental in development of a so much delicate system. The equipment used to support this long and crucial phase can be described as a set of Mechanical and Electrical Ground Support Equipment (EGSE). This paper describes the approach followed to develop such a system, and the benefits that this brings in terms of lower risk, more coordinated interfaces and improved functionality. The paper briefly outlines VEGA Electrical Ground Support Equipment major characteristics. In particular, this paper describes the EGSE design for a small launch vehicle such as VEGA. The objective of EGSE is to provide hardware and software for efficient electrical testing of either single stages and integrated launcher. The needs to develop a small launcher is a response to a Resolution in the Space Transportation Strategy adopted by the ESA Council in June 2000, aiming at: "completing, in the medium term, the range of launch services offered by the addition of European manufactured small and medium launcher, complementary to Ariane, consistent with diversified users' needs and relying on common elements, such as stages, subsystems, technologies, production facilities and operational infrastructure, thereby increasing the European launcher industry's competitiveness". Three different parts principally compose the Vega EGSE: TCS (Test Configuration System), TES (Test Execution System), PPS (Post Processing System). The TES is the part of the EGSE devoted to the tests execution; it has capabilities of immediate test data analysis, parameters monitoring and it is able to undertake pre-defined actions, in case of anomalous events happen, in order to put in safe conditions the Unity Under Test (UUT). The TES is composed of two main components: HLCS and LLCS. The HLCS is based on SCOS 2000 ESA product; it is mainly devoted to the interaction with operators. It allows loading Test Sequences and

  10. An ESA roadmap for geobiology in space exploration

    NASA Astrophysics Data System (ADS)

    Cousins, Claire R.; Cockell, Charles S.

    2016-01-01

    Geobiology, and in particular mineral-microbe interactions, has a significant role to play in current and future space exploration. This includes the search for biosignatures in extraterrestrial environments, and the human exploration of space. Microorganisms can be exploited to advance such exploration, such as through biomining, maintenance of life-support systems, and testing of life-detection instrumentation. In view of these potential applications, a European Space Agency (ESA) Topical Team "Geobiology in Space Exploration" was developed to explore these applications, and identify research avenues to be investigated to support this endeavour. Through community workshops, a roadmap was produced, with which to define future research directions via a set of 15 recommendations spanning three key areas: Science, Technology, and Community. These roadmap recommendations identify the need for research into: (1) new terrestrial space-analogue environments; (2) community level microbial-mineral interactions; (3) response of biofilms to the space environment; (4) enzymatic and biochemical mineral interaction; (5) technical refinement of instrumentation for space-based microbiology experiments, including precursor flight tests; (6) integration of existing ground-based planetary simulation facilities; (7) integration of fieldsite biogeography with laboratory- and field-based research; (8) modification of existing planetary instruments for new geobiological investigations; (9) development of in situ sample preparation techniques; (10) miniaturisation of existing analytical methods, such as DNA sequencing technology; (11) new sensor technology to analyse chemical interaction in small volume samples; (12) development of reusable Lunar and Near Earth Object experimental platforms; (13) utility of Earth-based research to enable the realistic pursuit of extraterrestrial biosignatures; (14) terrestrial benefits and technological spin-off from existing and future space

  11. Space Weather studies with a fleet of ESA SREM monitors

    NASA Astrophysics Data System (ADS)

    Hajdas, Wojtek; Evans, Hugh; Mohammadzadeh, Ali; Nieminen, Petteri; Desorgher, Laurent; Buehler, Paul; Daly, Eamonn

    2012-07-01

    Reliable observations and studies of Space Weather are based on precisely correlated network of specialized and well calibrated instruments. Such devices are able to provide simultaneously a set of 3D data encompassing large volume of the Earth magnetosphere. The fleet of ESA Standard Radiation Environment Monitors (SREM) is an example of such a network. SREM is a particle detector capable of detection of electrons (E > 500 keV) and protons (E > 8 MeV) with fair spectral and angular resolution. Six of them have been already launched onboard of Proba-1, Rosetta, INTEGRAL, Giove-B, Herschel and Planck missions. As single devices they are able to follow local Space Weather conditions providing accurate measurements of proton and electron spectra. As a network they allow for correlated observations of the radiation environments 3D variability. It includes not only the dynamics of the radiation belts but also propagation of Solar Energetic Particles as well as mapping of Forbusch decreases from coupling of Cosmic Rays and Coronal Mass Ejections. We present the SREM Data Bank open to the public and discuss its main features. Typical examples of the raw data corresponding to the physical phenomena listed above will also be shown. We will also discuss several data conversions algorithms leading to the particle spectra. A comparison between various methods such as simple algorithms, neural network or minimization will be discussed. Several other aspects of the SREM data analysis such as particle identification and separation or flux anisotropy level will also be addressed. Finally we provide short introduction for using of the SREM DB and its main analysis tools.

  12. The ESA Virtual Space Weather Modelling Centre - Phase 1

    NASA Astrophysics Data System (ADS)

    Poedts, Stefaan

    The ESA ITT project (AO/1-6738/11/NL/AT) to develop Phase 1 of a Virtual Space Weather Modelling Centre has the following objectives and scope: 1. The construction of a long term (~10 yrs) plan for the future development of a European virtual space weather modelling centre consisting of a new ‘open’ and distributed framework for the coupling of physics based models for space weather phenomena; 2. The assessment of model capabilities and the amount of work required to make them operational by integrating them in this framework and the identification of computing and networking requirements to do so. 3. The design of a system to enable models and other components to be installed locally or geographically distributed and the creation of a validation plan including a system of metrics for testing results. The consortium that took up this challenge involves: 1)the Katholieke Universiteit Leuven (Prime Contractor, coordinator: Prof. S. Poedts); 2) the Belgian Institute for Space Aeronomy (BIRA-IASB); 3) the Royal Observatory of Belgium (ROB); 4) the Von Karman Institute (VKI); 5) DH Consultancy (DHC); 6) Space Applications Services (SAS). The project started on May 14 2012, and will finish in May 2014. Thus, by the time of the meeting, both Phase 1A and Phase 1B (the development of the prototype) will be finished. The final report will be presented incl. the architecture decisions made, the framework, the current models integrated already as well as the model couplers installed. The prototype VSWMC will be demonstrated.

  13. Ultraviolet absorption spectrum of HOCl

    NASA Technical Reports Server (NTRS)

    Burkholder, James B.

    1993-01-01

    The room temperature UV absorption spectrum of HOCl was measured over the wavelength range 200 to 380 nm with a diode array spectrometer. The absorption spectrum was identified from UV absorption spectra recorded following UV photolysis of equilibrium mixtures of Cl2O/H2O/HOCl. The HOCl spectrum is continuous with a maximum at 242 nm and a secondary peak at 304 nm. The measured absorption cross section at 242 nm was (2.1 +/- 0.3) x 10 exp -19/sq cm (2 sigma error limits). These results are in excellent agreement with the work of Knauth et al. (1979) but in poor agreement with the more recent measurements of Mishalanie et al. (1986) and Permien et al. (1988). An HOCl nu2 infrared band intensity of 230 +/- 35/sq cm atm was determined based on this UV absorption cross section. The present results are compared with these previous measurements and the discrepancies are discussed.

  14. ESA's Integral detects closest cosmic gamma-ray burst

    NASA Astrophysics Data System (ADS)

    2004-08-01

    5 August 2004 A gamma-ray burst detected by ESA's Integral gamma-ray observatory on 3 December 2003 has been thoroughly studied for months by an armada of space and ground-based observatories. Astronomers have now concluded that this event, called GRB 031203, is the closest cosmic gamma-ray burst on record, but also the faintest. This also suggests that an entire population of sub-energetic gamma-ray bursts has so far gone unnoticed... Gamma ray burst model hi-res Size hi-res: 22 KB Credits: CXC/M. Weiss Artist impression of a low-energy gamma-ray burst This illustration describes a model for a gamma-ray burst, like the one detected by Integral on 3 December 2003 (GRB 031203). A jet of high-energy particles from a rapidly rotating black hole interacts with surrounding matter. Observations with Integral on 3 December 2003 and data on its afterglow, collected afterwards with XMM-Newton, Chandra and the Very Large Array telescope, show that GRB 031203 radiated only a fraction of the energy of normal gamma-ray bursts. Like supernovae, gamma-ray bursts are thought to be produced by the collapse of the core of a massive star. However, while the process leading to supernovae is relatively well understood, astronomers still do not know what happens when a core collapses to form a black hole. The discovery of 'under-energetic' gamma-ray bursts, like GRB 031203, should provide valuable clues as to links between supernovae, black holes and gamma-ray bursts. Lo-res JPG (22 Kb) Hi-res TIFF (5800 Kb) Cosmic gamma-ray bursts (GRBs) are flashes of gamma rays that can last from less than a second to a few minutes and occur at random positions in the sky. A large fraction of them is thought to result when a black hole is created from a dying star in a distant galaxy. Astronomers believe that a hot disc surrounding the black hole, made of gas and matter falling onto it, somehow emits an energetic beam parallel to the axis of rotation. According to the simplest picture, all GRBs

  15. ESA NEOCC effort to eliminate high Palermo Scale virtual impactors

    NASA Astrophysics Data System (ADS)

    Micheli, M.; Koschny, D.; Hainaut, O.; Bernardi, F.

    2014-07-01

    At the moment of this writing about 4 % of the known near-Earth objects are known to have at least one future close approach scenario with a non-negligible collision probability within the next century, as routinely computed by the NEODyS and Sentry systems. The most straightforward way to improve the knowledge of the future dynamics of an NEO in order to exclude (or possibly confirm) some of these possible future impact is to obtain additional astrometric observations of the object as soon as it becomes observable again. In particular, since a large fraction (>98 %) of the known objects currently recognized as possible future impactors have been observed during a single opposition, this usually corresponds to obtaining a new set of observations during a second opposition, a so called ''recovery''. However, in some cases the future observability windows for the target after the discovery apparition may be very limited, either because the object is intrinsically small (and therefore requires a very close and consequently rare approach to become observable) or because its orbital dynamic prevents the observability from the ground for a long timespan (as in the case of quasi-resonant objects with a long synodic period). When this happens, the only short-term way to clarify an impact scenario is to look toward the past, and investigate the possibility that unrecognized detections of the object are already present in the databases of old astronomical images, which are often archived by professional telescopes and made available to the community a few months to years after they are exposed. We will here present an effort lead by the newly formed ESA NEO Coordination Centre (NEOCC) in Frascati to pursue both these avenues with the intent of improving the orbital knowledge of the highest-rated possible impactors, as defined by the Palermo Technical Impact Hazard Scale (PS in the following). As an example of our ongoing observational activities, we will first present our

  16. Interaction of wide-band-gap single crystals with 248-nm excimer laser irradiation. X. Laser-induced near-surface absorption in single-crystal NaCl

    SciTech Connect

    Nwe, K.H.; Langford, S.C.; Dickinson, J.T.; Hess, W.P.

    2005-02-15

    Ultraviolet laser-induced desorption of neutral atoms and molecules from nominally transparent, ionic materials can yield particle velocities consistent with surface temperatures of a few thousand kelvin even in the absence of visible surface damage. The origin of the laser absorption required for this surface heating has been often overlooked. In this work, we report simultaneous neutral emission and laser transmission measurements on single-crystal NaCl exposed to 248-nm excimer laser radiation. As much as 20% of the incident radiation at 248 nm must be absorbed in the near-surface region to account for the observed particle velocities. We show that the laser absorption grows from low values over several pulses and saturates at values sufficient to account for the surface temperatures required to explain the observed particle velocity distributions. The growth of absorption in these early pulses is accompanied by a corresponding increase in the emission intensities. The diffuse reflectance spectra acquired after exposure suggest that near-surface V-type centers are responsible for most of the absorption at 248 nm in single-crystal NaCl.

  17. A new model for pressure-induced shifts of electronic absorption bands as applied to neat CS sub 2 and CS sub 2 in n-hexane and dichloromethane solutions

    SciTech Connect

    Agnew, S.F.; Swanson, B.I. )

    1990-01-25

    The authors propose a model for the pressure dependence of electronic absorption spectra and apply it to the authors data on CS{sub 2} both in neat phase and in hexane and dichloromethane solid solutions. They believe that their data represent a rather severe test of this model and argue that any model for the pressure dependence of electronic absorption spectra must include certain minimal effects - dispersive or dielectric and repulsive or volume effects - in order to adequately represent the data. They discuss previous models at some length in order to delineate the limits of their applicability. They further acknowledge and define the limits of the applicability of their model to solvent-induced shifts in general.

  18. Dual band metamaterial perfect absorber based on artificial dielectric “molecules”

    NASA Astrophysics Data System (ADS)

    Liu, Xiaoming; Lan, Chuwen; Li, Bo; Zhao, Qian; Zhou, Ji

    2016-07-01

    Dual band metamaterial perfect absorbers with two absorption bands are highly desirable because of their potential application areas such as detectors, transceiver system, and spectroscopic imagers. However, most of these dual band metamaterial absorbers proposed were based on resonances of metal patterns. Here, we numerically and experimentally demonstrate a dual band metamaterial perfect absorber composed of artificial dielectric “molecules” with high symmetry. The artificial dielectric “molecule” consists of four “atoms” of two different sizes corresponding to two absorption bands with near unity absorptivity. Numerical and experimental absorptivity verify that the dual-band metamaterial absorber is polarization insensitive and can operate in wide-angle incidence.

  19. Interaction of Wide-Band-Gap Single Crystals with 248-nm Excimer Laser Irradiation: X. Laser-Induced Near-Surface Absorption in Single-Crystal NaCl

    SciTech Connect

    Nwe, K H.; Langford, Stephen C.; Dickinson, J T.; Hess, Wayne P.

    2005-02-15

    Ultraviolet laser-induced desorption of neutral atoms and molecules from nominally transparent, ionic materials can yield particle velocities consistent with surface temperatures of a few thousand Kelvin, even in the absence of visible surface damage. The origin of the laser required for this surface heating has been often overlooked. In this work, we report simultaneous neutral emission and laser transmission measurements on single crystal NaCl exposed to 248-nm excimer laser radiation. As much as 20% of the incident radiation at 248 nm must be absorbed in the near surface region to account for the observed particle velocities. We show that the laser absorption grows from low values over several pulses and saturates at values sufficient to account for the surface temperatures required to explain the observed particle velocity distributions. The growth of absorption in these early pulses is accompanied by a corresponding increase in the emission intensities. Diffuse reflectance spectra acquired after exposure suggest that near surface V-type centers are responsible for most of the absorption at 248 nm in single crystal NaCl.

  20. Infrared laser absorption spectroscopy of the nu4 (sigma u) fundamental and associated nu11(pi u) hot band of C7 - Evidence for alternating rigidity in linear carbon clusters

    NASA Technical Reports Server (NTRS)

    Heath, J. R.; Saykally, R. J.

    1991-01-01

    The first characterization of the bending potential of the C7 cluster is reported via the observation of the v = 1(1) and v = 2 deg levels of the nu11 (pi u) bend as hot bands associated with the nu4 (sigma u) antisymmetric stretch fundamental. The lower state hot band rotational constants are measured to be 1004.4(1.3) and 1123.6(9.0) MHz, constituting a 9.3 and 22 percent increase over the ground state rotational constant, 918.89 (41) MHz. These large increases are strong quartic and sextic centrifugal distortion constants determined for the ground and nu 4 = 1 states are found to be anomalously large and negative, evidencing strong perturbations between stretching and bending modes.

  1. Optical absorption components of light-modulated absorption spectrum of CdS

    NASA Technical Reports Server (NTRS)

    Conway, E. J.; Long, E. R.

    1975-01-01

    The amplitude and decay coefficient of light-induced modulation of absorption (LIMA) was measured as a function of wavelength from 535 to 850 nm for single-crystal CdS. The decay coefficient exhibited a discontinuous resonance at 710 nm which was due to the overlap and cancellation of two opposing absorption changes. A method was developed to separate these opposing absorption changes using the measured decay coefficients. The discrete-level-to-band energy for one absorption change was found to be 1.64 eV. An improved model was developed which contains two associated levels in the band gap separated by 0.32 eV.

  2. ESA's Hipparcos satellite revises the scale of the cosmos

    NASA Astrophysics Data System (ADS)

    1997-02-01

    Sun, called parallaxes, give the first direct measurements of the distances of large numbers of stars. With the overall calculations completed, the harvest of scientific discoveries has begun. Among those delighted with the immediate irruption into cosmology, from this spacecraft made in Europe, is ESA's director of science, Roger Bonnet. "When supporters of the Hipparcos project argued their case," Bonnet recalls, "they were competing with astrophysical missions with more obvious glamour. But they promised remarkable consequences for all branches of astronomy. And already we see that even the teams using the Hubble Space Telescope will benefit from a verdict from Hipparcos on the distance scale that underpins all their reckonings of the expansion of the Universe." The pulse-rates of the stars Cepheid stars alternately squeeze themselves and relax, like a beating heart. They wax and wane rhythmically in brightness, every few days or weeks, at a rate that depends on their luminosity. Henrietta Leavitt at the Harvard College Observatory discovered in the early years of this century that bigger and more brilliant Cepheids vary with a longer period, according to a strict rule. It allows astronomers to gauge relative distances simply by taking the pulse-rates of the Cepheids and measuring their apparent brightnesses. Nearby Cepheids are typically 1000-2000 light-years away. They are too far for even Hipparcos to obtain very exact distance measurements, but by taking twenty-six examples and comparing them, Michael Feast and his colleague Robin Catchpole of RGO Cambridge arrive at consistent statistics. These define the relationship between the period and the luminosity, needed to judge the distances of Cepheids. The zero point is for an imaginary Cepheid pulsating once a day. This would be a star 300 times more luminous than the Sun, according to the Hipparcos data. The slowest Cepheid in the sample, l Carinae, has a period of 36 days and is equivalent to 18,000 suns

  3. CERN, ESA and ESO Launch "Physics On Stage"

    NASA Astrophysics Data System (ADS)

    2000-03-01

    Physics is everywhere . The laws of physics govern the Universe, the Sun, the Earth and even our own lives. In today's rapidly developing society, we are becoming increasingly dependent on high technology - computers, transport, and communication are just some of the key areas that are the result of discoveries by scientists working in physics. But how much do the citizens of Europe really know about physics? Here is a unique opportunity to learn more about this elusive subject! [Go to Physics On Stage Website] Beginning in February 2000, three major European research organisations are organising a unique Europe-wide programme to raise the public awareness of physics and related sciences. "Physics on Stage" is launched by the European Laboratory for Particle Physics (CERN) , the European Space Agency (ESA) and the European Southern Observatory (ESO) , with support from the European Union. Other partners are the European Physical Society (EPS) and the European Association for Astronomy Education (EAAE). This exciting programme is part of the European Week for Science and Technology and will culminate in a Science Festival during November 6-11, 2000, on the CERN premises at the French-Swiss border near Geneva. Why "Physics on Stage"? The primary goal of "Physics on Stage" is to counteract the current decline in interest and knowledge about physics among Europe's citizens by means of a series of highly visible promotional activities. It will bring together leading scientists and educators, government bodies and the media, to confront the diminishing attraction of physics to young people and to develop strategies to reverse this trend. The objective in the short term is to infuse excitement and to provide new educational materials. In the longer term, "Physics on Stage" will generate new developments by enabling experts throughout Europe to meet, exchange and innovate. "Physics on Stage" in 22 European Countries "Physics on Stage" has been initiated in 22 European

  4. Aerosol climate time series from ESA Aerosol_cci (Invited)

    NASA Astrophysics Data System (ADS)

    Holzer-Popp, T.

    2013-12-01

    Within the ESA Climate Change Initiative (CCI) the Aerosol_cci project (mid 2010 - mid 2013, phase 2 proposed 2014-2016) has conducted intensive work to improve algorithms for the retrieval of aerosol information from European sensors AATSR (3 algorithms), PARASOL, MERIS (3 algorithms), synergetic AATSR/SCIAMACHY, OMI and GOMOS. Whereas OMI and GOMOS were used to derive absorbing aerosol index and stratospheric extinction profiles, respectively, Aerosol Optical Depth (AOD) and Angstrom coefficient were retrieved from the other sensors. Global datasets for 2008 were produced and validated versus independent ground-based data and other satellite data sets (MODIS, MISR). An additional 17-year dataset is currently generated using ATSR-2/AATSR data. During the three years of the project, intensive collaborative efforts were made to improve the retrieval algorithms focusing on the most critical modules. The team agreed on the use of a common definition for the aerosol optical properties. Cloud masking was evaluated, but a rigorous analysis with a pre-scribed cloud mask did not lead to improvement for all algorithms. Better results were obtained using a post-processing step in which sudden transitions, indicative of possible occurrence of cloud contamination, were removed. Surface parameterization, which is most critical for the nadir only algorithms (MERIS and synergetic AATSR / SCIAMACHY) was studied to a limited extent. The retrieval results for AOD, Ångström exponent (AE) and uncertainties were evaluated by comparison with data from AERONET (and a limited amount of MAN) sun photometer and with satellite data available from MODIS and MISR. Both level2 and level3 (gridded daily) datasets were validated. Several validation metrics were used (standard statistical quantities such as bias, rmse, Pearson correlation, linear regression, as well as scoring approaches to quantitatively evaluate the spatial and temporal correlations against AERONET), and in some cases

  5. Has ESA's XMM-Newton cast doubt over dark energy?

    NASA Astrophysics Data System (ADS)

    2003-12-01

    Galaxy cluster RXJ0847 hi-res Size hi-res: 100k Galaxy cluster RXJ0847 The fuzzy object at the centre of the frame is one of the galaxy clusters observed by XMM-Newton in its investigation of the distant Universe. The cluster, designated RXJ0847.2+3449, is about 7 000 million light years away, so we see it here as it was 7 000 million years ago, when the Universe was only about half of its present age. This cluster is made up of several dozen galaxies. Observations of eight distant clusters of galaxies, the furthest of which is around 10 thousand million light years away, were studied by an international group of astronomers led by David Lumb of ESA's Space Research and Technology Centre (ESTEC) in the Netherlands. They compared these clusters to those found in the nearby Universe. This study was conducted as part of the larger XMM-Newton Omega Project, which investigates the density of matter in the Universe under the lead of Jim Bartlett of the College de France. Clusters of galaxies are prodigious emitters of X-rays because they contain a large quantity of high-temperature gas. This gas surrounds galaxies in the same way as steam surrounds people in a sauna. By measuring the quantity and energy of X-rays from a cluster, astronomers can work out both the temperature of the cluster gas and also the mass of the cluster. Theoretically, in a Universe where the density of matter is high, clusters of galaxies would continue to grow with time and so, on average, should contain more mass now than in the past. Most astronomers believe that we live in a low-density Universe in which a mysterious substance known as 'dark energy' accounts for 70% of the content of the cosmos and, therefore, pervades everything. In this scenario, clusters of galaxies should stop growing early in the history of the Universe and look virtually indistinguishable from those of today. In a paper soon to be published by the European journal Astronomy and Astrophysics, astronomers from the XMM

  6. NASA and ESA Collaboration on Hexavalent Chrome Alternatives Pretreatments Only Interim Test Report

    NASA Technical Reports Server (NTRS)

    Kessel, Kurt R.

    2015-01-01

    NASA and ESA continue to search for an alternative to hexavalent chromium in coatings applications that meet their performance requirements in corrosion protection, cost, operability, and health and safety, while typically specifying that performance must be equal to or greater than existing systems. The overall objective of the collaborative effort between NASA TEERM and ESA is to test and evaluate coating systems (pretreatments, pretreatments with primer, and pretreatments with primer and topcoat) as replacements for hexavalent chrome coatings in aerospace applications. This objective will be accomplished by testing promising coatings identified from previous NASA, ESA, Department of Defense (DOD), and other project experience. Additionally, several new materials will be analyzed according to ESA-identified specifications.

  7. ANALYTICAL METHOD DEVELOPMENT FOR ALACHLOR ESA AND OTHER ACETANILIDE HERBICIDE DEGRADATION PRODUCTS

    EPA Science Inventory

    In 1998, USEPA published a Drinking Water Contaminant Candidate List (CCL) of 50 chemicals and 10 microorganisms. "Alachlor ESA and other acetanilide herbicide degradation products" is listed on the the 1998 CCL. Acetanilide degradation products are generally more water soluble...

  8. NASA AND ESA Partnership on the Multi-Purpose Crew Vehicle Service Module

    NASA Technical Reports Server (NTRS)

    Free, James M.; Schubert, Kathleen; Grantier, Julie

    2012-01-01

    In March 2011, NASA and ESA made a decision to partially offset the European obligations deriving from the extension of the ISS Program until the end of 2020 with different means than ATVs, following the ATV-5 mission foreseen in mid-2014. NASA and ESA considered a number of barter options, and concluded that the provision by ESA of the Service Module and Spacecraft Adaptor for the NASA Multi-Purpose Crew Vehicle (MPCV) was the barter element with the most interest. A joint ESA - NASA working group was established to assess the feasibility of Europe developing this Module based on ATV heritage. The working group was supported by European and US industry namely Astrium, TAS-I and Lockheed-Martin. This paper gives an overview of the results of the on-going study as well as its projected utilization for the global space exploration endeavour.

  9. Acyl-homoserine lactone recognition and response hindering the quorum-sensing regulator EsaR.

    PubMed

    Schu, Daniel J; Scruggs, Jessica M; Geissinger, Jared S; Michel, Katherine G; Stevens, Ann M

    2014-01-01

    During quorum sensing in the plant pathogen Pantoea stewartii subsp. stewartii, EsaI, an acyl-homoserine lactone (AHL) synthase, and the transcription factor EsaR coordinately control capsular polysaccharide production. The capsule is expressed only at high cell density when AHL levels are high, leading to inactivation of EsaR. In lieu of detailed structural information, the precise mechanism whereby EsaR recognizes AHL and is hindered by it, in a response opposite to that of most other LuxR homologues, remains unresolved. Hence, a random mutagenesis genetic approach was designed to isolate EsaR* variants that are immune to the effects of AHL. Error-prone PCR was used to generate the desired mutants, which were subsequently screened for their ability to repress transcription in the presence of AHL. Following sequencing, site-directed mutagenesis was used to generate all possible mutations of interest as single, rather than multiple amino acid substitutions. Eight individual amino acids playing a critical role in the AHL-insensitive phenotype have been identified. The ability of EsaR* variants to bind AHL and the effect of individual substitutions on the overall conformation of the protein were examined through in vitro assays. Six EsaR* variants had a decreased ability to bind AHL. Fluorescence anisotropy was used to examine the relative DNA binding affinity of the final two EsaR* variants, which retained some AHL binding capability but remained unresponsive to it, perhaps due to an inability of the N-terminal domain to transduce information to the C-terminal domain. PMID:25238602

  10. Acyl-Homoserine Lactone Recognition and Response Hindering the Quorum-Sensing Regulator EsaR

    PubMed Central

    Schu, Daniel J.; Scruggs, Jessica M.; Geissinger, Jared S.; Michel, Katherine G.; Stevens, Ann M.

    2014-01-01

    During quorum sensing in the plant pathogen Pantoea stewartii subsp. stewartii, EsaI, an acyl-homoserine lactone (AHL) synthase, and the transcription factor EsaR coordinately control capsular polysaccharide production. The capsule is expressed only at high cell density when AHL levels are high, leading to inactivation of EsaR. In lieu of detailed structural information, the precise mechanism whereby EsaR recognizes AHL and is hindered by it, in a response opposite to that of most other LuxR homologues, remains unresolved. Hence, a random mutagenesis genetic approach was designed to isolate EsaR* variants that are immune to the effects of AHL. Error-prone PCR was used to generate the desired mutants, which were subsequently screened for their ability to repress transcription in the presence of AHL. Following sequencing, site-directed mutagenesis was used to generate all possible mutations of interest as single, rather than multiple amino acid substitutions. Eight individual amino acids playing a critical role in the AHL-insensitive phenotype have been identified. The ability of EsaR* variants to bind AHL and the effect of individual substitutions on the overall conformation of the protein were examined through in vitro assays. Six EsaR* variants had a decreased ability to bind AHL. Fluorescence anisotropy was used to examine the relative DNA binding affinity of the final two EsaR* variants, which retained some AHL binding capability but remained unresponsive to it, perhaps due to an inability of the N-terminal domain to transduce information to the C-terminal domain. PMID:25238602

  11. A simplified method to detect epididymal sperm aneuploidy (ESA) in mice using three-chromosome fish

    SciTech Connect

    Lowe, X.; O`Hogan, S.; Wyrobek, A.

    1995-11-01

    We developed a new method (ESA) to detect aneuploidy and polyploidy in epididymal sperm of mice using three-chromosome FISH. In comparison to a previous method (TSA-testicular spermatid aneuploidy), which required late-step spermatids, the ESA method utilizes epididymal sperm, which are easier to collect than testicular cells. The ESA method also provides a homogenous population of cells, which significantly speeds up the scoring procedure. A total of 6 mice were investigated by the ESA method and results compared with those obtained by the TSA method: 2 mice each of Robertsonian (8.14) heterozygotes, Rb(8.14) homozygotes and B6C3F1. About 10,000 sperm were scored per mouse. For the ESA method, epididimides were cut into small pieces and filtered. Sperm were prepared for hybridization by sonication and a modification of the DTT/LIS method previously described. Sperm aneuploidy was detected by multi-color FISH using three DNA probes specific for mouse chromosomes X, Y and 8. The sex ratio of X8(49.7%) and Y8(49.6%) did not differ from the expected 1:1. The efficiency of ESA was very high; -0.3% of the cells showed no hybridization domain. Hyperhaploidy frequencies for chromosomes X, Y and 8 compared well between the ESA and TSA methods for Rb(8.14) heterozygous (p=0.79) and B6C3F1 mice (p>0.05). The data obtained from Rb(8.14) homozygotes were similar to those from B6C3F1, as predicted (p=0.3). This highly efficient ESA assay is therefore, recommended for future studies of the mechanism of induction of aneuploidy in male germ cells. It also lays a solid foundation for automated scoring.

  12. Selective coherent perfect absorption in metamaterials

    SciTech Connect

    Nie, Guangyu; Shi, Quanchao; Zhu, Zheng; Shi, Jinhui

    2014-11-17

    We show multi-band coherent perfect absorption (CPA) in simple bilayered asymmetrically split ring metamaterials. The selectivity of absorption can be accomplished by separately excited electric and magnetic modes in a standing wave formed by two coherent counterpropagating beams. In particular, each CPA can be completely switched on/off by the phase of a second coherent wave. We propose a practical scheme for realizing multi-band coherent perfect absorption of 100% that is allowed to work from microwave to optical frequency.

  13. NASA and ESA Partnership on the Multi-Purpose Crew Vehicle Service Module

    NASA Technical Reports Server (NTRS)

    Schubert, Kathleen E.; Grantier, Julie A.

    2012-01-01

    (1) ESA decided in its Council Meeting in March 2011 to partially offset the European ISS obligations after 2015 with different means than ATVs; (2) The envisioned approach is based on a barter element(s) that would generate cost avoidance on the NASA side; (3) NASA and ESA considered a number of Barter options, NASA concluded that the provision by ESA of the Service Module for the NASA Multi-Purpose Crew Vehicle (MPCV) was the barter with the most interest;. (4) A joint ESA - NASA working group was established in May 2011 to assess the feasibility of Europe developing this Module based on ATV heritage; (5)The working group was supported by European and US industry namely Astrium, TAS-I and Lockheed-Martin; and (6) The project is currently in phase B1 with the objective to prepare a technical and programmatic proposal for an ESA MPCV-SM development. This proposal will be one element of the package that ESA plans submit to go forward for approval by European Ministers in November 2012.

  14. Intramolecular charge transfer of 4-(dimethylamino)benzonitrile probed by time-resolved fluorescence and transient absorption: No evidence for two ICT states and a {pi}{sigma}{sup *} reaction intermediate

    SciTech Connect

    Zachariasse, Klaas A.; Druzhinin, Sergey I.; Senyushkina, Tamara; Kovalenko, Sergey A.

    2009-12-14

    For the double exponential fluorescence decays of the locally excited (LE) and intramolecular charge transfer (ICT) states of 4-(dimethylamino)benzonitrile (DMABN) in acetonitrile (MeCN) the same times {tau}{sub 1} and {tau}{sub 2} are observed. This means that the reversible LE<-->ICT reaction, starting from the initially excited LE state, can be adequately described by a two state mechanism. The most important factor responsible for the sometimes experimentally observed differences in the nanosecond decay time, with {tau}{sub 1}(LE)<{tau}{sub 1}(ICT), is photoproduct formation. By employing a global analysis of the LE and ICT fluorescence response functions with a time resolution of 0.5 ps/channel in 1200 channels reliable kinetic and thermodynamic data can be obtained. The arguments presented in the literature in favor of a {pi}{sigma}* state with a bent CN group as an intermediate in the ICT reaction of DMABN are discussed. From the appearance of an excited state absorption (ESA) band in the spectral region between 700 and 800 nm in MeCN for N,N-dimethylanilines with CN, Br, F, CF{sub 3}, and C(=O)OC{sub 2}H{sub 2} p-substituents, it is concluded that this ESA band cannot be attributed to a {pi}{sigma}{sup *} state, as only the C-C{identical_to}N group can undergo the required 120 deg. bending.

  15. ESA is hot on the trail of Geminga

    NASA Astrophysics Data System (ADS)

    XMM-Newton image of Geminga showing the discovery of the twi hi-res Size hi-res: 68 kb Credits: ESA XMM-Newton image of Geminga showing the discovery of the twin tails This image was captured by the EPIC camera on board the satellite. The motion of Geminga across the sky is indicated, showing that the tails are trailing the neutron star. The scale bar corresponds to a distance of 1.5 million million kilometres at the distance of Geminga. Computer models of the shock wave created by Geminga hi-res Size hi-res: 522 kb Credits: Patrizia Caraveo Computer models of the shockwave created by Geminga Computer models of the shockwave created by Geminga show that the best matches to the data occur if the neutron star is travelling virtually across our line of sight. These correspond to the inclinations of less than 30 degrees. A neutron star measures only 20-30 kilometres across and is the dense remnant of an exploded star. Geminga is one of the closest to Earth, at a distance of about 500 light-years. Most neutron stars emit radio emissions, appearing to pulsate like a lighthouse, but Geminga is 'radio-quiet'. It does, however, emit huge quantities of pulsating gamma rays making it one of the brightest gamma-ray sources in the sky. Geminga is the only example of a successfully identified gamma-ray source from which astronomers have gained significant knowledge. It is 350 000 years old and ploughs through space at 120 kilometres per second. Its route creates a shockwave that compresses the gas of the interstellar medium and its naturally embedded magnetic field by a factor of four. Patrizia Caraveo, Instituto di Astrofisica Spaziale e Fisica Cosmica, Milano, Italy, and her colleagues (at CESR, France, ESO and MPE, Germany) have calculated that the tails are produced because highly energetic electrons become trapped in this enhanced magnetic field. As the electrons spiral inside the magnetic field, they emit the X-rays seen by XMM-Newton. The electrons themselves are created

  16. A vista of new knowledge from ESA's Hipparcos astronomy mission

    NASA Astrophysics Data System (ADS)

    1997-05-01

    Hipparcos is a milestone in the history of astronomy. In 1985 the American physicist Freeman J. Dyson hailed Hipparcos as the first major new development in space science to come from outside the United States. The spacecraft operated in orbit 1989-93, measuring the angles between stars in the sky. Over a further three years, computing teams across Europe generated a consistent, high-precision plot of 118,000 stars in the Hipparcos Catalogue and somewhat less accurate (but still unprecedented) data on a million stars in the Tycho Catalogue. The distances, motions, pairings and variability of stars are now known far more accurately than ever before. Hipparcos will make an impact on every branch of astronomy, from the Solar System to the history of the Universe, and especially on theories of stars and their evolution. For almost a year, astronomers most closely associated with the mission have had an early view of the completed catalogues and in Venice they will summarize their initial results. The Hipparcos data will be published in June, as an extraordinary contribution from Europe to astronomy all around the world. The success of Hipparcos has created problems for the organizers of Venice symposium. Altogether 190 scientific papers were offered for presentation by various groups of astronomers. With three mornings and three afternoons available for the main scientific sessions, 67 oral presentations are accommodated, by restricting speakers to 10-15 minutes each. For the rest, there will a generous display of results in the form of posters. Thus Hipparcos will be celebrated by a vista of new knowledge. The stars are looking younger Already Hipparcos seems to cure a headache concerning the ages of stars. As recently as last year, astronomers were perplexed by a contradiction between their estimates of the age of the Universe, and stars that seemed to be older. An early Hipparcos result announced in February 1997 (ESA Information Note 04/97) concerned the winking

  17. Detection of hydrogen fluoride absorption in diffuse molecular clouds with Herschel/HIFI: an ubiquitous tracer of molecular gas

    NASA Astrophysics Data System (ADS)

    Sonnentrucker, P.; Neufeld, D. A.; Phillips, T. G.; Gerin, M.; Lis, D. C.; de Luca, M.; Goicoechea, J. R.; Black, J. H.; Bell, T. A.; Boulanger, F.; Cernicharo, J.; Coutens, A.; Dartois, E.; Kaźmierczak, M.; Encrenaz, P.; Falgarone, E.; Geballe, T. R.; Giesen, T.; Godard, B.; Goldsmith, P. F.; Gry, C.; Gupta, H.; Hennebelle, P.; Herbst, E.; Hily-Blant, P.; Joblin, C.; Kołos, R.; Krełowski, J.; Martín-Pintado, J.; Menten, K. M.; Monje, R.; Mookerjea, B.; Pearson, J.; Perault, M.; Persson, C. M.; Plume, R.; Salez, M.; Schlemmer, S.; Schmidt, M.; Stutzki, J.; Teyssier, D.; Vastel, C.; Yu, S.; Caux, E.; Güsten, R.; Hatch, W. A.; Klein, T.; Mehdi, I.; Morris, P.; Ward, J. S.

    2010-10-01

    We discuss the detection of absorption by interstellar hydrogen fluoride (HF) along the sight line to the submillimeter continuum sources W49N and W51. We have used Herschel's HIFI instrument in dual beam switch mode to observe the 1232.4762 GHz J = 1-0 HF transition in the upper sideband of the band 5a receiver. We detected foreground absorption by HF toward both sources over a wide range of velocities. Optically thin absorption components were detected on both sight lines, allowing us to measure - as opposed to obtain a lower limit on - the column density of HF for the first time. As in previous observations of HF toward the source G10.6-0.4, the derived HF column density is typically comparable to that of water vapor, even though the elemental abundance of oxygen is greater than that of fluorine by four orders of magnitude. We used the rather uncertain N(CH)-N(H2) relationship derived previously toward diffuse molecular clouds to infer the molecular hydrogen column density in the clouds exhibiting HF absorption. Within the uncertainties, we find that the abundance of HF with respect to H2 is consistent with the theoretical prediction that HF is the main reservoir of gas-phase fluorine for these clouds. Thus, hydrogen fluoride has the potential to become an excellent tracer of molecular hydrogen, and provides a sensitive probe of clouds of small H2 column density. Indeed, the observations of hydrogen fluoride reported here reveal the presence of a low column density diffuse molecular cloud along the W51 sight line, at an LSR velocity of ~24 km s-1, that had not been identified in molecular absorption line studies prior to the launch of Herschel. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

  18. Suppression of thermal carrier escape and efficient photo-carrier generation by two-step photon absorption in InAs quantum dot intermediate-band solar cells using a dot-in-well structure

    SciTech Connect

    Asahi, S.; Teranishi, H.; Kasamatsu, N.; Kada, T.; Kaizu, T.; Kita, T.

    2014-08-14

    We investigated the effects of an increase in the barrier height on the enhancement of the efficiency of two-step photo-excitation in InAs quantum dot (QD) solar cells with a dot-in-well structure. Thermal carrier escape of electrons pumped in QD states was drastically reduced by sandwiching InAs/GaAs QDs with a high potential barrier of Al{sub 0.3}Ga{sub 0.7}As. The thermal activation energy increased with the introduction of the barrier. The high potential barrier caused suppression of thermal carrier escape and helped realize a high electron density in the QD states. We observed efficient two-step photon absorption as a result of the high occupancy of the QD states at room temperature.

  19. Demonstration That Calibration of the Instrument Response to Polarizations Parallel and Perpendicular to the Object Space Projected Slit of an Imaging Spectrometer Enable Measurement of the Atmospheric Absorption Spectrum in Region of the Weak CO2 Band for the Case of Arbitrary Polarization: Implication for the Geocarb Mission

    NASA Astrophysics Data System (ADS)

    Kumer, J. B.; Rairden, R. L.; Polonsky, I. N.; O'Brien, D. M.

    2014-12-01

    The Tropospheric Infrared Mapping Spectrometer (TIMS) unit rebuilt to operate in a narrow spectral region, approximately 1603 to 1615 nm, of the weak CO2 band as described by Kumer et al. (2013, Proc. SPIE 8867, doi:10.1117/12.2022668) was used to conduct the demonstration. An integrating sphere (IS), linear polarizers and quarter wave plate were used to confirm that the instrument's spectral response to unpolarized light, to 45° linearly polarized light and to circular polarized light are identical. In all these cases the intensity components Ip = Is where Ip is the component parallel to the object space projected slit and Is is perpendicular to the slit. In the circular polarized case Ip = Is in the time averaged sense. The polarizer and IS were used to characterize the ratio Rθ of the instrument response to linearly polarized light at the angle θ relative to parallel from the slit, for increments of θ from 0 to 90°, to that of the unpolarized case. Spectra of diffusely reflected sunlight passed through the polarizer in increments of θ, and divided by the respective Rθ showed identical results, within the noise limit, for solar spectrum multiplied by the atmospheric transmission and convolved by the Instrument Line Shape (ILS). These measurements demonstrate that unknown polarization in the diffusely reflected sunlight on this small spectral range affect only the slow change across the narrow band in spectral response relative to that of unpolarized light and NOT the finely structured / high contrast spectral structure of the CO2 atmospheric absorption that is used to retrieve the atmospheric content of CO2. The latter is one of the geoCARB mission objectives (Kumer et al, 2013). The situation is similar for the other three narrow geoCARB bands; O2 A band 757.9 to 768.6 nm; strong CO2 band 2045.0 to 2085.0 nm; CH4 and CO region 2300.6 to 2345.6 nm. Polonsky et al have repeated the mission simulation study doi:10.5194/amt-7-959-2014 assuming no use of a geo

  20. Come to Noyon (France) and follow the solar eclipse with ESA

    NASA Astrophysics Data System (ADS)

    1999-08-01

    ESA will feature a special exhibition stand where the public, amateurs and press can obtain information. During the partial eclipse phases, the latest images from ESA's solar observatory SOHO and from other European eclipse sites, coming via the Internet or traditional broadcast, will be shown on a large video screen. The magic of the total eclipse in Noyon will last 2 minutes and 11 seconds. ESA has set up a multi-site eclipse imaging campaign over Europe to capture a long eclipse sequence from the Atlantic, the UK, France (Noyon and Strasbourg), Germany, Austria/ Hungary (at an international camp of young astronomers) and Romania. High-definition still and video images of the eclipse will be available live on the Internet. Check our site http://sci.esa.int/eclipse99/ Noyon will also host a press briefing at the eclipse site Media Centre at 9h30-10h30, and again at 13h15-14h15, after the eclipse shadow has left Europe. Opportunities for interviews with ESA multi-language staff and other specialists will be possible after the eclipse. Over the week leading up to the eclipse, ESA representatives are also participating in press and public conferences. Daily press conferences are scheduled in Strasbourg at the France 3 Auditorium from 4 to 11 August at 16:00-18:00 hrs, in Paris at the Museum d'Histoire Naturelle from 5 -12 August (except 11 August) at 10:00-12:00 hrs, and in Stuttgart at the Science Fair, where an ESA/Max Plank Institute stand has also been set up.

  1. The European space exploration programme: current status of ESA's plans for Moon and Mars exploration.

    PubMed

    Messina, Piero; Vennemann, Dietrich

    2005-01-01

    After a large consultation with the scientific and industrial communities in Europe, the Aurora Space Exploration Programme was unanimously approved at the European Space Agency (ESA) Council at ministerial level in Edinburgh in 2001. This marked the start of the programme's preparation phase that was due to finish by the end of 2004. Aurora features technology development robotic and crewed rehearsal missions aimed at preparing a human mission to Mars by 2033. Due to the evolving context, both international and European, ESA has undertaken a review of the goals and approach of its exploration programme. While maintaining the main robotic missions that had been conceived during Aurora, the European Space Exploration Programme that is currently being proposed to the Aurora participating states and other ESA Member States has a reviewed approach and will feature a greater synergy with other ESA programmes. The paper will present the process that led to the revision of ESA's plans in the field of exploration and will give the current status of the programme. PMID:16010757

  2. ABSORPTION ANALYZER

    DOEpatents

    Brooksbank, W.A. Jr.; Leddicotte, G.W.; Strain, J.E.; Hendon, H.H. Jr.

    1961-11-14

    A means was developed for continuously computing and indicating the isotopic assay of a process solution and for automatically controlling the process output of isotope separation equipment to provide a continuous output of the desired isotopic ratio. A counter tube is surrounded with a sample to be analyzed so that the tube is exactly in the center of the sample. A source of fast neutrons is provided and is spaced from the sample. The neutrons from the source are thermalized by causing them to pass through a neutron moderator, and the neutrons are allowed to diffuse radially through the sample to actuate the counter. A reference counter in a known sample of pure solvent is also actuated by the thermal neutrons from the neutron source. The number of neutrons which actuate the detectors is a function of a concentration of the elements in solution and their neutron absorption cross sections. The pulses produced by the detectors responsive to each neu tron passing therethrough are amplified and counted. The respective times required to accumulate a selected number of counts are measured by associated timing devices. The concentration of a particular element in solution may be determined by utilizing the following relation: T2/Ti = BCR, where B is a constant proportional to the absorption cross sections, T2 is the time of count collection for the unknown solution, Ti is the time of count collection for the pure solvent, R is the isotopic ratlo, and C is the molar concentration of the element to be determined. Knowing the slope constant B for any element and when the chemical concentration is known, the isotopic concentration may be readily determined, and conversely when the isotopic ratio is known, the chemical concentrations may be determined. (AEC)

  3. IRRS, UV-Vis-NIR absorption and photoluminescence upconversion in Ho{sup 3+}-doped oxyfluorophosphate glasses

    SciTech Connect

    Karmakar, Basudeb . E-mail: basudebk@cgcri.res.in

    2005-09-15

    Infrared reflection spectroscopic (IRRS), ultraviolet-visible-near infrared (UV-Vis-NIR) absorption and photoluminescence upconversion properties with special emphasis on the spectrochemistry of the oxyfluorophosphate (oxide incorporated fluorophosphates) glasses of the Ba(PO{sub 3}){sub 2}-AlF{sub 3}-CaF{sub 2}-SrF{sub 2}-MgF{sub 2}-Ho{sub 2}O{sub 3} system have been studied with different concentrations (0.1, 0.3 and 1.0 mol%) of Ho{sub 2}O{sub 3}. IRRS spectral band position and intensity of Ho{sup 3+} ion doped oxyfluorophosphate glasses have been discussed in terms of reduced mass and force constant. UV-Vis-NIR absorption band position has been justified with quantitative calculation of nephelauxetic parameter and covalent bonding characteristics of the host. NIR to visible upconversion has been investigated by exciting at 892 nm at room temperature. Three upconverted bands originated from the {sup 5}F{sub 3}{yields}{sup 5}I{sub 8} ({sup 5}S{sub 2}, {sup 5}F{sub 4}){yields}{sup 5}I{sub 8} and {sup 5}F{sub 5}{yields}{sup 5}I{sub 8} transitions have found to be centered at 491 nm (blue, medium), 543 nm (green, very strong) and 658 nm (red, weak), respectively. These bands have been justified from the evaluation of the absorption, normal (down conversion) fluorescence and excitation spectra. The upconversion processes have been explained by the excited state absorption (ESA), energy transfer (ET) and cross relaxation (CR) mechanisms involving population of the metastable (storage) energy levels by multiphonon deexcitation effect. It is evident from the IRRS study that the upconversion phenomena are expedited by the low multiphonon relaxation rate in oxyfluorophosphate glasses owing to their high intense low phonon energy ({approx}600 cm{sup -1}) which is very close to that of fluoride glasses (500-600 cm{sup -1})

  4. First observation of 628 CO 2 isotopologue band at 3.3 μm in the atmosphere of Venus by solar occultation from Venus Express

    NASA Astrophysics Data System (ADS)

    Bertaux, Jean-Loup; Vandaele, Ann Carine; Wilquet, Valérie; Montmessin, F.; Dahoo, R.; Villard, E.; Korablev, O.; Fedorova, A.

    2008-05-01

    The new ESA Venus Express orbiter is the first mission applying the probing technique of solar and stellar occultation to the atmosphere of Venus, with the SPICAV/SOIR instrument. SOIR is a new type of spectrometer used for solar occultations in the range 2.2-4.3 μm. Thanks to a high spectral resolving power R˜15,000-20,000 (unprecedented in planetary space exploration), a new gaseous absorption band was soon detected in the atmospheric transmission spectra around 2982 cm -1, showing a structure resembling an unresolved Q branch and a number of isolated lines with a regular wave number pattern. This absorption could not be matched to any species contained in HITRAN or GEISA databases, but was found very similar to an absorption pattern observed by a US team in the spectrum of solar light reflected by the ground of Mars [Villanueva, G.L., Mumma, M.J., Novak, R.E., Hewagama, T., 2008. Icarus 195 (1), 34-44]. This team then suggested to us that the absorption was due to an uncatalogued transition of the 16O 12C 18O molecule. The possible existence of this band was soon confirmed from theoretical considerations by Perevalov and Tashkun. Some SOIR observations of the atmospheric transmission are presented around 2982 cm -1, and rough calculations of line strengths of the Q branch are produced, based on the isotopic ratio measured earlier in the lower atmosphere of Venus. This discovery emphasizes the role of isotopologues of CO 2 (as well as H 2O and HDO) as important greenhouse gases in the atmosphere of Venus.

  5. Cost considerations in database selection - A comparison of DIALOG and ESA/IRS

    NASA Technical Reports Server (NTRS)

    Jack, R. F.

    1984-01-01

    It is pointed out that there are many factors which affect the decision-making process in determining which databases should be selected for conducting the online search on a given topic. In many cases, however, the major consideration will be related to cost. The present investigation is concerned with a comparison of the costs involved in making use of DIALOG and the European Space Agency's Information Retrieval Service (ESA/IRS). The two services are very comparable in many respects. Attention is given to pricing structure, telecommunications, the number of databases, prints, time requirements, a table listing online costs for DIALOG and ESA/IRS, and differences in mounting databases. It is found that ESA/IRS is competitively priced when compared to DIALOG, and, despite occasionally higher telecommunications costs, may be even more economical to use in some cases.

  6. Cloud absorption radiometer

    NASA Technical Reports Server (NTRS)

    Strange, M. G.

    1988-01-01

    The Cloud Absorption Radiometer (CAR) was developed to measure spectrally how light is scattered by clouds and to determine the single scattering albedo, important to meteorology and climate studies, with unprecedented accuracy. This measurement is based on ratios of downwelling to upwelling radiation within clouds, and so is not strongly dependent upon absolute radiometric calibration of the instrument. The CAR has a 5-inch aperture and 1 degree IFOV, and spatially scans in a plane orthogonal to the flight vector from the zenith to nadir at 1.7 revolutions per second. Incoming light is measured in 13 spectral bands, using silicon, germanium, and indium-antimonide detectors. Data from each channel is digitally recorded in flight with 10-bit (0.1 percent) resolution. The instrument incorporates several novel features. These features are briefly detailed.

  7. Cloud Information Content Analysis for EPIC's Oxygen A- and B-band Channels

    NASA Astrophysics Data System (ADS)

    Davis, A. B.; Sanghavi, S.

    2011-12-01

    The Earth Polychromatic Imaging Camera (EPIC) instrument on the Deep Space Climate Observatory (DSCOVR) will have two molecular oxygen channels: one for the well-known ``A'' band at~764 nm and one for the weaker ``B'' band at 688~nm. In both cases, a channel-integrated relative measurement of absorption is possible using an ``in-band'' channel and a nearby ``reference'' channel. Together, these four observations enable a rudimentary differential optical absorption spectroscopy (DOAS) of O2 in the characteristic retro-reflection geometry of the L1 vantage point. A priori, we thus have at best two new pieces of cloud information to access. EPIC's pixels have 10x10 km2 footprints at nadir (center of the illuminated disk), more as the viewing angle increases away from local zenith. What new information can be learned about clouds from these data on a pixel-by-pixel basis? O2 A-band observations from space have been pioneered with CNES's POLDER, ESA's SCIAMACHY, and JAXA's GOSat. NASA's OCO-2, to be launched in early 2013, will also have A-band capability. POLDER has low spectral and spatial resolutions, but offers multiple viewing directions for every pixel; SCIAMACHY has higher spectral but worse spatial resolution and just one viewing angle. GOSat has very high spectral but rather low spatial resolutions, again with the possibility of dense angular sampling, but no imaging (just one pixel at a time). OCO-2, a narrow swath imager, will have similarly high spectral resolution and reasonably high ( ˜2~km) spatial resolution. Of these four LEO missions, two are focused on CO2 DOAS, with O2 being assayed operationally only to deliver it in ppm's. POLDER and SCIAMACHY however have official cloud products based on A-band measurements. They contain, at the least, an estimate of cloud top height and, at the most, that plus an estimate of cloud pressure thickness. Cloud optical depth and effective particle size are derived from other spectral data, including continuum values

  8. Current band model studies of CH4 at wavelengths less than 2.5 microns

    NASA Technical Reports Server (NTRS)

    Fink, U.

    1982-01-01

    Band model theories are used to calculate the transmission of the methane spectrum. In a band model the monochromatic absorption coefficient over a small wavelength interval is replaced, and an average pressure coefficient is introduced. Two main types of band models were developed. The first is the 'regular' band model, in which the lines in a band are presumed evenly spaced; this is also called the Elsasser band model. In the second type of band model, the lines are randomly spaced; this is often referred to as the Mayor-Goody band model. The methane spectrum is sufficiently irregular that the second band model, the irregular band model, should apply.

  9. The europa initiative for esa's cosmic vision: a potential european contribution to nasa's Europa mission

    NASA Astrophysics Data System (ADS)

    Blanc, Michel; Jones, Geraint H.; Prieto-Ballesteros, Olga; Sterken, Veerle J.

    2016-04-01

    The assessment of the habitability of Jupiter's icy moons is considered of high priority in the roadmaps of the main space agencies, including the decadal survey and esa's cosmic vision plan. the voyager and galileo missions indicated that europa and ganymede may meet the requirements of habitability, including deep liquid aqueous reservoirs in their interiors. indeed, they constitute different end-terms of ocean worlds, which deserve further characterization in the next decade. esa and nasa are now both planning to explore these ice moons through exciting and ambitious missions. esa selected in 2012 the juice mission mainly focused on ganymede and the jupiter system, while nasa is currently studying and implementing the europa mission. in 2015, nasa invited esa to provide a junior spacecraft to be carried on board its europa mission, opening a collaboration scheme similar to the very successful cassini-huygens approach. in order to define the best contribution that can be made to nasa's europa mission, a europa initiative has emerged in europe. its objective is to elaborate a community-based strategy for the proposition of the best possible esa contribution(s) to nasa's europa mission, as a candidate for the upcoming selection of esa's 5th medium-class mission . the science returns of the different potential contributions are analysed by six international working groups covering complementary science themes: a) magnetospheric interactions; b) exosphere, including neutrals, dust and plumes; c) geochemistry; d) geology, including expressions of exchanges between layers; e) geophysics, including characterization of liquid water distribution; f) astrobiology. each group is considering different spacecraft options in the contexts of their main scientific merits and limitations, their technical feasibility, and of their interest for the development of esa-nasa collaborations. there are five options under consideration: (1) an augmented payload to the europa mission main

  10. Upgrade of DRAMA-ESA's Space Debris Mitigation Analysis Tool Suite

    NASA Astrophysics Data System (ADS)

    Gelhaus, Johannes; Sanchez-Ortiz, Noelia; Braun, Vitali; Kebschull, Christopher; de Oliveira, Joaquim Correia; Dominguez-Gonzalez, Raul; Wiedemann, Carsten; Krag, Holger; Vorsmann, Peter

    2013-08-01

    One decade ago ESA started the dev elopment of the first version of the software tool called DRAMA (Debris Risk Assessment and Mitigation Analysis) to enable ESA space programs to assess their compliance with the recommendations in the European Code of Conduct for Space Debris Mitigation. This tool was maintained, upgraded and extended during the last year and is now a combination of five individual tools, each addressing a different aspect of debris mitigation. This paper gives an overview of the new DRAMA software in general. Both, the main tools ARES, OSCAR, MIDAS, CROC and SARA will be discussed and the environment used by DRAMA will be explained shortly.

  11. Latest processing status and quality assessment of the GOMOS, MIPAS and SCIAMACHY ESA dataset

    NASA Astrophysics Data System (ADS)

    Niro, F.; Brizzi, G.; Saavedra de Miguel, L.; Scarpino, G.; Dehn, A.; Fehr, T.; von Kuhlmann, R.

    2011-12-01

    GOMOS, MIPAS and SCIAMACHY instruments are successfully observing the changing Earth's atmosphere since the launch of the ENVISAT-ESA platform on March 2002. The measurements recorded by these instruments are relevant for the Atmospheric-Chemistry community both in terms of time extent and variety of observing geometry and techniques. In order to fully exploit these measurements, it is crucial to maintain a good reliability in the data processing and distribution and to continuously improving the scientific output. The goal is to meet the evolving needs of both the near-real-time and research applications. Within this frame, the ESA operational processor remains the reference code, although many scientific algorithms are nowadays available to the users. In fact, the ESA algorithm has a well-established calibration and validation scheme, a certified quality assessment process and the possibility to reach a wide users' community. Moreover, the ESA algorithm upgrade procedures and the re-processing performances have much improved during last two years, thanks to the recent updates of the Ground Segment infrastructure and overall organization. The aim of this paper is to promote the usage and stress the quality of the ESA operational dataset for the GOMOS, MIPAS and SCIAMACHY missions. The recent upgrades in the ESA processor (GOMOS V6, MIPAS V5 and SCIAMACHY V5) will be presented, with detailed information on improvements in the scientific output and preliminary validation results. The planned algorithm evolution and on-going re-processing campaigns will be mentioned that involves the adoption of advanced set-up, such as the MIPAS V6 re-processing on a clouds-computing system. Finally, the quality control process will be illustrated that allows to guarantee a standard of quality to the users. In fact, the operational ESA algorithm is carefully tested before switching into operations and the near-real time and off-line production is thoughtfully verified via the

  12. Computer programs for absorption spectrophotometry.

    PubMed

    Jones, R N

    1969-03-01

    Brief descriptions are given of twenty-two modular computer programs for performing the basic numerical computations of absorption spectrophotometry. The programs, written in Fortran IV for card input and output, are available from the National Research Council of Canada. The input and output formats are standardized to permit easy interfacing to yield more complex data processing systems. Though these programs were developed for ir spectrophotometry, they are readily modified for use with digitized visual and uv spectrophotometers. The operations covered include ordinate and abscissal unit and scale interconversions, ordinate addition and subtraction, location of band maxima and minima, smoothing and differentiation, slit function convolution and deconvolution, band profile analysis and asymmetry quantification, Fourier transformation to time correlation curves, multiple overlapping band separation in terms of Cauchy (Lorentz), Gauss, Cauchy-Gauss product, and Cauchy-Gauss sum functions and cell path length determination from fringe spacing analysis. PMID:20072266

  13. Microwave and optical saturable absorption in graphene.

    PubMed

    Zheng, Zhiwei; Zhao, Chujun; Lu, Shunbin; Chen, Yu; Li, Ying; Zhang, Han; Wen, Shuangchun

    2012-10-01

    We report on the first experiments on saturable absorption in graphene at microwave frequency band. Almost independent of the incident frequency, microwave absorbance of graphene always decreases with increasing the power and reaches at a constant level for power larger than 80 µW, evidencing the microwave saturable absorption property of graphene. Optical saturable absorption of the same graphene sample was also experimentally confirmed by an open-aperture Z-scan technique by one laser at telecommunication band and another pico-second laser at 1053 nm, respectively. Herein, we are able to conclude that graphene is indeed a broadband saturable absorber that can operate at both microwave and optical band. PMID:23188285

  14. A band enhanced metamaterial absorber based on E-shaped all-dielectric resonators

    NASA Astrophysics Data System (ADS)

    Li, Liyang; Wang, Jun; Du, Hongliang; Wang, Jiafu; Qu, Shaobo; Xu, Zhuo

    2015-01-01

    In this paper, we propose a band enhanced metamaterial absorber in microwave band, which is composed of high-permittivity E-shaped dielectric resonators and metallic ground plate. The E-shaped all-dielectric structure is made of high-temperature microwave ceramics with high permittivity and low loss. An absorption band with 1 GHz bandwidth for both TE and TM polarizations are observed. Moreover, the absorption property is stable under different incident angles. The band enhanced absorption is caused by different resonant modes which lie closely in the absorption band. Due to the enhanced localized electric/magnetic fields at the resonant frequencies, strong absorptions are produced. Our work provides a new method of designing high-temperature and high-power microwave absorbers with band enhanced absorption.

  15. The Colour and Stereo Surface Imaging System for ESA's Trace Gas Orbiter

    NASA Astrophysics Data System (ADS)

    Thomas, Nicolas; Cremonese, Gabriele

    2016-04-01

    The Colour and Stereo Surface Imaging System (CaSSIS) is an 11 μrad/px imaging system ready to launch on the European Space Agency's (ESA) ExoMars Trace Gas Orbiter (TGO) on 14 March 2016 from Baikonur. CaSSIS is based around an 880 mm focal length carbon-fibre reinforced polymer (CFRP) telescope with a 135 mm primary mirror and a 2k x 2k CMOS hybrid detector with 10 micron pixel pitch providing 4.6 m/px imaging from the nominal 400 km circular orbit. The telescope is a slightly modified three mirror anastigmat optical configuration with no central obscuration. The instrument is designed to operate in "push-frame" mode where 2048 x 256 images are acquired at a repetition rate which matches the ground-track velocity (~3 km/s) allowing sufficient overlap for co-registration thereby building image strips along the surface. A filter strip assembly (FSA) is mounted directly above the detector providing images in 4 wavelength bands. Two of these (480.5nm and 676.5nm prior to convolution with the rest of the instrument) correspond closely to bands used by the HiRISE instrument on the Mars Reconnaissance Orbiter [4]. Two other filters split the NIR wavelengths with centres at 838 nm and close to 985 nm. Analyses show that the filters provide good differentiation between expected surface minerals, particularly Fe-bearing phases (Tornabene et al. LPSC, 2016). CaSSIS is designed to produce stereo from images acquired ~30 s apart by using a rotation drive. The telescope points 10 degrees off-nadir. The drive aligns the telescope with the ground-track direction so that the telescope is pointing forward. After image acquisition, the telescope is rapidly rotated by 180 degrees to point in the opposite direction and the second image of the stereo pair is acquired. CaSSIS will extend the monitoring of past missions to future years allowing the tracking of longer-term changes. It will also provide contemporaneous imaging of regions that may produce unique signatures detected by

  16. The design of Janus, the visible camera for the ESA JUICE mission

    NASA Astrophysics Data System (ADS)

    Della Corte, Vincenzo; Schmitz, Nicole; Castro, José Maria; Leese, Mark; Debei, Stefano; Magrin, Demetrio; Michalik, Harald

    2014-05-01

    The JUICE (JUpiter ICy moons Explorer) mission was selected in May 2012 as the first Large mission in the frame of the ESA Cosmic Vision 2015-2025 program. The mission is aimed at an in-depth characterization of the Jovian system, with an operational phase of about 3.5 years. During the whole operational phase, JANUS (Jovis, Amorum ac Natorum Undique Scrutator) will acquire panchromatic and narrow-band images in the visible - NIR range of many targets within the Jovian system: the Galilean satellites surfaces and exospheres, Jupiter atmosphere, minor and irregular satellites, the ring system. After a long trade-off between different design solutions, based on performance requirements, mission design and constraints, the present JANUS design has been based on the following architectural choices detailed below. A catoptric telescope with excellent optical quality is coupled with a framing CMOS detector, avoiding any scan-ning mechanism or operational requirement on the S/C. The three mirror anastigmatic (TMA) off-axis design with F#=4.67 allows an MTF between 62% and 72% at Nyquist, with good straylight rejection. The detector is the CIS115 from e2v; it is a CMOS with a squared 7 micron pixel pitch and image format of 2000x1504. It performs a high readout rate of up to 40 Mpixel/s, high quantum efficiency and low readout noise and dark signal. Fine tuning of instrument parameters allows to perform both high resolution targeted observations and lower resolution global coverage of targets, as required to meet science objectives. The IFoV (Fieldo of View per pixel) is 15 microrad, al-lowing sampling of 7.5 m/pixel from 500 km and 15 km/pixel from 10E6 km, while the FoV is 1.72x1.29 deg. The acquisition parameters allow to cope with the many different observation requirements and conditions that JANUS will face. Design of the two electronics units (a proximity electronics controlling the detector and a main electronics controlling the instrument and the interfaces with

  17. ESA successfully conducts experiment in Advanced Space Robotics on Japanese satellite

    NASA Astrophysics Data System (ADS)

    1999-04-01

    ETS-VII is the latest in NASDA's series of engineering test satellites. It is dedicated to the in-orbit assessment and demonstration of novel technologies in rendez-vous / docking and space robotics. ETS-VII is in fact a pair of satellites, a larger chaser and a smaller target satellite which can be released for the rendez-vous and docking experiments. The larger satellite carries a robot arm with a stretched length of about 2 m, and a set of experimentation equipment to test the robot's capabilities : a task board on which typical robot manipulation activities can be performed and measured, an Orbital Replacement Unit (ORU) to be removed and reinstalled, a truss structure to be erected, an antenna assembly mechanism to be actuated and an advanced robot hand. The ESA experiments concern advanced schemes for planning, commanding, controlling and monitoring the activities of a space robot arm system. One set of experiments tests an operational mode called "interactive autonomy", whereby the robot motions are split into typical "tasks" of medium complexity. Ground operators can interact with the tasks (parameterising, commanding, rescheduling, monitoring, interrupting them as needed), relying on the fact that each task will be autonomously executed using appropriate sensor-based control loops (it having been programmed and extensively verified in advance by simulation). This significantly reduces the amount of data traffic over the spacelink - in fact, ETS-VII offers only a few short communications windows per day. Data from ESA experiments will be used to assess the performance of tasks executed with "interactive autonomy" compared with the more traditional telemanipulation at lower control levels. The second group of experiments concerns vision-based robot control. Using the Japanese-provided on-board vision system (which includes one hand camera and one scene-overview camera), it has been demonstrated that reliable automatic object localisation and grasping can be

  18. A Simple Band for Gastric Banding.

    PubMed

    Broadbent

    1993-08-01

    The author has noted that flexible gastric bands have occasionally stenosed the gastric stoma or allowed it to dilate. A band was developed using a soft outer silicone rubber tube over a holding mechanism made out of a nylon cable tie passed within the silicone tube. This simple, easily applied band is rigid, resisting scar contracture and dilatation. PMID:10757939

  19. Interpretation of the Minkowski bands in Grw + 70 deg 8247.

    NASA Technical Reports Server (NTRS)

    Angel, J. R. P.

    1972-01-01

    Demonstration on the basis of the spectral structure of circular polarization in Grw + 70 deg 8247, that the absorption bands are at least in part molecular in origin. The spectrum of molecular helium has strong bands coincident with several of the Minkowski bands and, in particular, at high temperature shows a strong band head at about 4125 A. Helium molecules could be formed in sufficient density to give the absorption features in the star if it has a pure helium atmosphere. The Zeeman effect in molecular helium can explain in general the observed spectral features in the polarization and also may be responsible for the continuum polarization.

  20. The GOME-type Total Ozone Essential Climate Variable (GTO-ECV) data record from the ESA Climate Change Initiative

    NASA Astrophysics Data System (ADS)

    Coldewey-Egbers, M.; Loyola, D. G.; Koukouli, M.; Balis, D.; Lambert, J.-C.; Verhoelst, T.; Granville, J.; van Roozendael, M.; Lerot, C.; Spurr, R.; Frith, S. M.; Zehner, C.

    2015-09-01

    We present the new GOME-type Total Ozone Essential Climate Variable (GTO-ECV) data record which has been created within the framework of the European Space Agency's Climate Change Initiative (ESA-CCI). Total ozone column observations - based on the GOME-type Direct Fitting version 3 algorithm - from GOME (Global Ozone Monitoring Experiment), SCIAMACHY (SCanning Imaging Absorption SpectroMeter for Atmospheric CHartographY), and GOME-2 have been combined into one homogeneous time series, thereby taking advantage of the high inter-sensor consistency. The data record spans the 15-year period from March 1996 to June 2011 and it contains global monthly mean total ozone columns on a 1°× 1° grid. Geophysical ground-based validation using Brewer, Dobson, and UV-visible instruments has shown that the GTO-ECV level 3 data record is of the same high quality as the equivalent individual level 2 data products that constitute it. Both absolute agreement and long-term stability are excellent with respect to the ground-based data, for almost all latitudes apart from a few outliers which are mostly due to sampling differences between the level 2 and level 3 data. We conclude that the GTO-ECV data record is valuable for a variety of climate applications such as the long-term monitoring of the past evolution of the ozone layer, trend analysis and the evaluation of chemistry-climate model simulations.

  1. The GOME-type Total Ozone Essential Climate Variable (GTO-ECV) data record from the ESA Climate Change Initiative

    NASA Astrophysics Data System (ADS)

    Coldewey-Egbers, M.; Loyola, D. G.; Koukouli, M.; Balis, D.; Lambert, J.-C.; Verhoelst, T.; Granville, J.; van Roozendael, M.; Lerot, C.; Spurr, R.; Frith, S. M.; Zehner, C.

    2015-05-01

    We present the new GOME-type Total Ozone Essential Climate Variable (GTO-ECV) data record which has been created within the framework of the European Space Agency's Climate Change Initiative (ESA-CCI). Total ozone column observations - based on the GOME-type Direct Fitting version 3 algorithm - from GOME (Global Ozone Monitoring Experiment), SCIAMACHY (SCanning Imaging Absorption SpectroMeter for Atmospheric CHartographY), and GOME-2 have been combined into one homogeneous time series, thereby taking advantage of the high inter-sensor consistency. The data record spans the 15-year period from March 1996 to June 2011 and it contains global monthly mean total ozone columns on a 1° × 1° grid. Geophysical ground-based validation using Brewer, Dobson, and UV-visible instruments has shown that the GTO-ECV level 3 data record is of the same high quality as the equivalent individual level 2 data products that constitute it. Both absolute agreement and long-term stability are excellent with respect to the ground-based data, for almost all latitudes apart from a few outliers which are mostly due to sampling differences between the level 2 and level 3 data. We conclude that the GTO-ECV data record is valuable for a variety of climate applications such as the long-term monitoring of the past evolution of the ozone layer, trend analysis and the evaluation of Chemistry-Climate Model simulations.

  2. Engineering the esaR promoter for tunable quorum sensing- dependent gene expression.

    PubMed

    Shong, Jasmine; Collins, Cynthia H

    2013-10-18

    Quorum sensing (QS) systems enable bacteria to coordinate their behavior as a function of local population density and are often used in synthetic systems that require cell−cell communication. We have engineered the esaR promoter, P(esaR), which is repressed by the QS regulator E(saR). E(saR)-dependent gene expression from P(esaR) is induced by 3-oxo-hexanoyl-homoserine lactone (3OC6HSL). Here, we report a set of modified P(esaR) promoters that contain a second E(saR) binding site. We observed changes in gene expression levels, regulatory range, 3OC6HSL sensitivity, and the regulatory role of E(saR) that are dependent on the position of the second binding site. Combining the new promoters with endogenous 3OC6HSL production led to QS-dependent systems that exhibit a range of expression levels and timing. These promoters represent a new set of tools for modulating QS-dependent gene expression and may be used to tune the regulation of multiple genes in response to a single QS signal. PMID:23879176

  3. Lunar PanCam: Adapting ExoMars PanCam for the ESA Lunar Lander

    NASA Astrophysics Data System (ADS)

    Coates, A. J.; Griffiths, A. D.; Leff, C. E.; Schmitz, N.; Barnes, D. P.; Josset, J.-L.; Hancock, B. K.; Cousins, C. R.; Jaumann, R.; Crawford, I. A.; Paar, G.; Bauer, A.; the PanCam Team

    2012-12-01

    A scientific camera system would provide valuable geological context from the surface for lunar lander missions. Here, we describe the PanCam instrument from the ESA ExoMars rover and its possible adaptation for the proposed ESA lunar lander. The scientific objectives of the ESA ExoMars rover are designed to answer several key questions in the search for life on Mars. The ExoMars PanCam instrument will set the geological and morphological context for that mission. We describe the PanCam scientific objectives in geology, and atmospheric science, and 3D vision objectives. We also describe the design of PanCam, which includes a stereo pair of Wide Angle Cameras (WACs), each of which has a filter wheel, and a High Resolution Camera for close up investigations. The cameras are housed in an optical bench (OB) and electrical interface is provided via the PanCam Interface Unit (PIU). Additional hardware items include a PanCam Calibration Target (PCT). We also briefly discuss some PanCam testing during field trials. In addition, we examine how such a 'Lunar PanCam' could be adapted for use on the Lunar surface on the proposed ESA lunar lander.

  4. Solar Flare Prediction Science-to-Operations: the ESA/SSA SWE A-EFFort Service

    NASA Astrophysics Data System (ADS)

    Georgoulis, Manolis K.; Tziotziou, Konstantinos; Themelis, Konstantinos; Magiati, Margarita; Angelopoulou, Georgia

    2016-07-01

    We attempt a synoptical overview of the scientific origins of the Athens Effective Solar Flare Forecasting (A-EFFort) utility and the actions taken toward transitioning it into a pre-operational service of ESA's Space Situational Awareness (SSA) Programme. The preferred method for solar flare prediction, as well as key efforts to make it function in a fully automated environment by coupling calculations with near-realtime data-downloading protocols (from the Solar Dynamics Observatory [SDO] mission), pattern recognition (solar active-region identification) and optimization (magnetic connectivity by simulated annealing) will be highlighted. In addition, the entire validation process of the service will be described, with its results presented. We will conclude by stressing the need for across-the-board efforts and synergistic work in order to bring science of potentially limited/restricted interest into realizing a much broader impact and serving the best public interests. The above presentation was partially supported by the ESA/SSA SWE A-EFFort project, ESA Contract No. 4000111994/14/D/MRP. Special thanks go to the ESA Project Officers R. Keil, A. Glover, and J.-P. Luntama (ESOC), M. Bobra and C. Balmer of the SDO/HMI team at Stanford University, and M. Zoulias at the RCAAM of the Academy of Athens for valuable technical help.

  5. Astronauts Jeffrey A. Hoffman (left) and Maurizio Cheli, representing European Space Agency (ESA),

    NASA Technical Reports Server (NTRS)

    1996-01-01

    STS-75 ONBOARD VIEW --- Astronauts Jeffrey A. Hoffman (left) and Maurizio Cheli, representing European Space Agency (ESA), set up an experiment at the glovebox on the Space Shuttle Columbias mid-deck. The two mission specialists joined three other astronauts and an international payload specialist for more than 16 days of research aboard Columbia.

  6. International cooperation in the field of space life sciences: European Space Agency's (ESA) perspectives.

    PubMed

    Oser, H

    1989-08-01

    International cooperation in life sciences, as in any other of the space research fields, takes place at two distinct levels: scientist to scientist, or agency to agency. This article is more concerned with the agency to agency level, which involves the arrangements made between two partners for the flying of experiments and/or hardware on space missions. International cooperation is inherent to the European Space Agency (ESA), since it consists of 13 member states (Austria, Belgium, Denmark, France, Ireland, Italy, the Netherlands, Norway, Spain, Sweden, Switzerland, United Kingdom, and West Germany) and one associated member, Finland. ESA also has special cooperative arrangements with Canada. Life sciences research in ESA is carried out within the Microgravity Research Program, an optional program to which member states (in this case all but Austria and Ireland) contribute "a la carte," and receive their "share" accordingly. Therefore, many of the activities are naturally linked to international arrangements within the member states, and also to arrangements between the agencies, with life sciences being the dominant activity between NASA and ESA. PMID:11592293

  7. Exploring NASA and ESA Atmospheric Data Using GIOVANNI, the Online Visualization and Analysis Tool

    NASA Technical Reports Server (NTRS)

    Leptoukh, Gregory

    2007-01-01

    Giovanni, the NASA Goddard online visualization and analysis tool (http://giovanni.gsfc.nasa.gov) allows users explore various atmospheric phenomena without learning remote sensing data formats and downloading voluminous data. Using NASA MODIS (Terra and Aqua) and ESA MERIS (ENVISAT) aerosol data as an example, we demonstrate Giovanni usage for online multi-sensor remote sensing data comparison and analysis.

  8. Korean Diaspora in the Age of Globalization: Early Study Abroad (ESA) College Students in the Midwest

    ERIC Educational Resources Information Center

    Choi, Hee Young

    2012-01-01

    This study examines the unique experiences of international Korean college students in the Midwest who have gone through the early study abroad (ESA) period in the US during their formative secondary school education and the influence of the experiences into their college lives in the mega campus. Two overarching research questions are: 1) how do…

  9. Overview of ESA life support activities in preparation of future exploration

    NASA Astrophysics Data System (ADS)

    Lasseur, Christophe; Paille, Christel

    2016-07-01

    Since 1987, the European Space Agency has been active in the field of Life Support development. When compare to its international colleagues, it is clear that ESA started activities in the field with a "delay of around 25 years. Due to this situation and to avoid duplication, ESA decided to focus more on long term manned missions and to consider more intensively regenerative technologies as well as the associated risks management ( e.g. physical, chemical and contaminants). Fortunately or not, during the same period, no clear plan of exploration and consequently not specific requirements materialized. This force ESA to keep a broader and generic approach of all technologies. Today with this important catalogue of technologies and know-how, ESA is contemplating the different scenario of manned exploration beyond LEO. In this presentation we review the key scenario of future exploration, and identify the key technologies who loo the more relevant. An more detailed status is presented on the key technologies and their development plan for the future.

  10. 78 FR 18585 - FIFRA Pesticide Registration Review and ESA Consultation Processes; Stakeholder Input; Notice of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-27

    ... AGENCY FIFRA Pesticide Registration Review and ESA Consultation Processes; Stakeholder Input; Notice of... availability of the final paper describing enhanced opportunities for stakeholder input during its review of... of Agriculture (USDA), and the National Marine Fisheries Service (NMFS) in the U.S. Department...

  11. Electrical signature analysis (ESA) developments at the Oak Ridge Diagnostics Applied Research Center

    SciTech Connect

    Haynes, H.D.

    1995-07-01

    Since 1985, researchers at the Oak Ridge National Laboratory (ORNL) have developed and patented several novel signal conditioning and signature analysis methods that have exploited the intrinsic abilities of conventional electric motors and generators to act as transducers. By using simple nonintrusive sensors such as clamp-on current and voltage probes, these new diagnostic techniques provide an improved means of detecting small time-dependent load and speed variations generated anywhere within an electromechanical system and converting them into revealing signatures that can be used to detect equipment degradation and incipient failures. These developments have been grouped under the general name of electrical signature analysis (ESA) and together provide a breakthrough in the ability to detect, analyze, and correct unwanted changes in process conditions or the presence of abnormalities in electrical and electromechanical equipment. Typical diagnostic information provided by ESA is comparable to that provided by conventional vibration analysis in that both time waveform and frequency spectrum signatures may be produced. The primary benefit of ESA is that an extensive range of diagnostic information can be obtained from a single transducer that may be installed several hundred feet or more from the monitored device on its electrical lines supplying input power (e.g., to a motor) or carrying output power (e.g., from a generator); thus, ESA is truly remote and nonintrusive.

  12. System assessment study of the ESA Darwin Mission: concepts trade-off and first iteration design on novel Emma arrangement

    NASA Astrophysics Data System (ADS)

    Ruilier, C.; Krawczyk, R.; Sghedoni, M.; Chanal, O.; Degrelle, C.; Pirson, L.; Simane, O.; Thomas, E.

    2007-09-01

    ESA's Darwin mission is devoted to direct detection and spectroscopic characterisation of Earth-like planets in the thermal infrared domain by nulling interferometry in space. This technique requires deep and stable starlight rejection to an efficiency around 106 over the whole spectral band. Darwin is a major target for Thales Alenia Space, and is considered as a strategic part of its programme roadmap. In this paper we present the main outcomes of the Darwin mission study conducted by Thales Alenia Space from Oct. 2005 to Jul. 2007. Studying this mission in depth, our proposed most promising configuration features spacecraft in non planar arrangement (called Emma). It offers the best science return in terms of number of stars detected and sky accessibility while staying compliant with mass and volume constraints of a single Ariane 5 launch. Our solution dramatically alleviates engineering constraints thanks to a fully non deployable concept. As compared to the more conventional planar arrangement (called Charles), Emma suppresses Single Point Failures and spurious flexible modes, thus maximising both the system reliability and the stability of the dynamical environment. Emma is fully compatible with either 3 or 4 collectors.

  13. ESA activities on satellite laser ranging to non-cooperative objects

    NASA Astrophysics Data System (ADS)

    Flohrer, Tim; Krag, Holger; Funke, Quirin; Jilete, Beatriz; Mancas, Alexandru

    2016-07-01

    Satellite laser ranging (SLR) to non-cooperative objects is an emerging technology that can contribute significantly to operational, modelling and mitigation needs set by the space debris population. ESA is conducting various research and development activities in SLR to non-cooperative objects. ESA's Space Situational Awareness (SSA) program supports specific activities in the Space Surveillance and Tracking (SST) segment. Research and development activities with operational aspects are run by ESA's Space Debris Office. At ESA SSA/SST comprises detecting, cataloguing and predicting the objects orbiting the Earth, and the derived applications. SST aims at facilitating research and development of sensor and data processing technologies and of related common components while staying complementary with, and in support of, national and multi-national European initiatives. SST promotes standardisation and interoperability of the technology developments. For SLR these goals are implemented through researching, developing, and deploying an expert centre. This centre shall coordinate the contribution of system-external loosely connected SLR sensors, and shall provide back calibration and expert evaluation support to the sensors. The Space Debris Office at ESA is responsible for all aspects related to space debris in the Agency. It is in charge of providing operational support to ESA and third party missions. Currently, the office studies the potential benefits of laser ranging to space debris objects to resolve close approaches to active satellites, to improve re-entry predictions of time and locations, and the more general SLR support during contingency situations. The office studies the determination of attitude and attitude motion of uncooperative objects with special focus on the combination of SLR, light-curve, and radar imaging data. Generating sufficiently precise information to allow for the acquisition of debris objects by a SLR sensor in a stare

  14. ESA's Support To Science Element (STSE): A New Opportunity for the Science Community

    NASA Astrophysics Data System (ADS)

    Fernández Prieto, D.; Herland, E.-A.

    2009-04-01

    In 1998, the document ESA SP-1227: "The Science and Research Elements of ESA's Living Planet Programme", laid out the research objectives for the scientific component of the Living Planet Program. These were formulated around four themes: Earth Interior, Physical Climate, Geosphere/Biosphere and Atmosphere & Marine Environment: Anthropogenic Impact. These themes encompassed the full scope of Earth Science. Although no specific area of Earth Science was prioritised, the document emphasised the need to move towards an integrated Earth System Model, where the role of internationally coordinated scientific programmes and coordination with national programmes and other agencies and organisations were recognised as being a key aspect of the science strategy. In 2006, the EO Science Strategy was updated (ESA/PB-EO(2006)89) under the auspices of the ESA's Earth Science Advisory Committee (ESAC) in wide consultation with the scientific community. The resulting document: "The Changing Earth - New Scientific Challenges for ESA's Living Planet Programme" (ESA/SP-1304) outlines the new scientific direction for the future progress of the ESA Living Planet Programme. In particular, the document set out the 25 major challenges for our understanding of the Earth System with especial focus on those areas of knowledge where satellite data may make a major contribution. Achieving those challenges will require a large international effort involving, novel observation, enhanced data sets, improved models and coordinated research. ESA is contributing to those efforts through its missions (e.g., the ERS1 and 2, ENVISAT, the Meteorological satellites and the coming Earth Explorers and Sentinel series) and exploitation programs. However, in order to further reinforce the ESA support to the scientific community, a dedicated element of the Envelop program was launched in 2008, the Support To Science Element (STSE). STSE aims at providing "scientific support for both future and on

  15. A model for the spectral dependence of optically induced absorption in amorphous silicon

    NASA Technical Reports Server (NTRS)

    Lawandy, N. M.

    1990-01-01

    A model based on transitions from localized band tail states to states above the mobility edge is used to explain the broad band induced absorptions observed in recent pump-probe experiments. The model gives the observed decrease of absorption with frequency at subband gap photo energies and high carrier densities (of about 10 to the 20th/cu cm). At lower carrier densities, the absorption has a maximun which is sensitive to the spatial extent of the band tail states.

  16. Strong terahertz absorption using thin metamaterial structures

    SciTech Connect

    Alves, Fabio; Kearney, Brian; Grbovic, Dragoslav; Lavrik, Nickolay V; Karunasiri, Gamani

    2012-01-01

    Metamaterial absorbers with nearly 100% absorption in the terahertz (THz) spectral band have been designed and fabricated using a periodic array of aluminum (Al) squares and an Al ground plane separated by a thin silicon dioxide (SiO{sub 2}) dielectric film. The entire structure is less than 1.6 mm thick making it suitable for the fabrication of microbolometers or bi-material sensors for THz imaging. Films with different dielectric layer thicknesses exhibited resonant absorption at 4.1, 4.2, and 4.5 THz with strengths of 98%, 95%, and 88%, respectively. The measured absorption spectra are in good agreement with simulations using finite element modeling.

  17. Inter-band optoelectronic properties in quantum dot structure of low band gap III-V semiconductors

    SciTech Connect

    Dey, Anup; Maiti, Biswajit; Chanda, Debasree

    2014-04-14

    A generalized theory is developed to study inter-band optical absorption coefficient (IOAC) and material gain (MG) in quantum dot structures of narrow gap III-V compound semiconductor considering the wave-vector (k{sup →}) dependence of the optical transition matrix element. The band structures of these low band gap semiconducting materials with sufficiently separated split-off valance band are frequently described by the three energy band model of Kane. This has been adopted for analysis of the IOAC and MG taking InAs, InSb, Hg{sub 1−x}Cd{sub x}Te, and In{sub 1−x}Ga{sub x}As{sub y}P{sub 1−y} lattice matched to InP, as example of III–V compound semiconductors, having varied split-off energy band compared to their bulk band gap energy. It has been found that magnitude of the IOAC for quantum dots increases with increasing incident photon energy and the lines of absorption are more closely spaced in the three band model of Kane than those with parabolic energy band approximations reflecting the direct the influence of energy band parameters. The results show a significant deviation to the MG spectrum of narrow-gap materials having band nonparabolicity compared to the parabolic band model approximations. The results reflect the important role of valence band split-off energies in these narrow gap semiconductors.

  18. Come Join the Band

    ERIC Educational Resources Information Center

    Olson, Cathy Applefeld

    2011-01-01

    A growing number of students in Blue Springs, Missouri, are joining the band, drawn by a band director who emphasizes caring and inclusiveness. In the four years since Melissia Goff arrived at Blue Springs High School, the school's extensive band program has swelled. The marching band alone has gone from 100 to 185 participants. Also under Goff's…

  19. Self-trapping and excited state absorption in fluorene homo-polymer and copolymers with benzothiadiazole and tri-phenylamine.

    PubMed

    Denis, Jean-Christophe; Ruseckas, Arvydas; Hedley, Gordon J; Matheson, Andrew B; Paterson, Martin J; Turnbull, Graham A; Samuel, Ifor D W; Galbraith, Ian

    2016-08-01

    Excited state absorption (ESA) is studied using time-dependent density functional theory and compared with experiments performed in dilute solutions. The molecules investigated are a fluorene pentamer, polyfluorene F8, the alternating F8 copolymer with benzothiadiazole F8BT, and two blue-emitting random copolymers F8PFB and F8TFB. Calculated and measured spectra show qualitatively comparable results. The ESA cross-section of co-polymers at its maximum is about three times lower than that of F8. The ESA spectra are found to change little upon structural relaxation of the excited state, or change in the order of sub-units in a co-polymer, for all studied molecules. In all these molecules, the strongest ESA transition is found to arise from the same electronic process, exhibiting a reversal of the charge parity. In addition, F8PFB and F8TFB are found to possess almost identical electronic behaviour. PMID:27439750

  20. The ESA STSE Changing Earth Science Network 2008-2013: Supporting The Next Generation Of European Scientists

    NASA Astrophysics Data System (ADS)

    Fernandez-Prieto, D.; Sabia, R.

    2013-12-01

    In 2006, the European Space Agency (ESA) published the document “The Changing Earth: New Scientific Challenges for ESA's Living Planet Programme” as the main driver of ESA's new Earth Observation (EO) science strategy. The document outlines 25 major scientific challenges covering all the different aspects of the Earth system, where EO technology and ESA missions may provide a key contribution. In this framework, and aiming at enhancing the ESA scientific support towards the achievement of “The Challenges”, the Agency has launched the “Changing Earth Science Network”, an important programmatic component of the new Support To Science Element (STSE) of the Earth Observation Envelope Programme (EOEP). In this paper, the objectives of this initiative are summarized and the list of the projects selected in the various calls is provided.