SCIENTIFIC AND TECHNICAL AEROSPACE REPORTS
A Biweekly Publication of the National Aeronautics and Space Administration
VOLUME 44, ISSUE 13 - JULY 05, 2006
90 ASTROPHYSICS
Includes cosmology; celestial mechanics; space plasmas; and interstellar and interplanetary gases and dust.
20060016390 McGill Univ., Montreal, Quebec, Canada
A Burst and Simultaneous Short-Term Pulsed Flux Enhancement From The Magnetar Candidate 1E 1048.1-5937
Gavriil, Fotis P.; Kaspi, Victoria M.; Woods, Peter M.; The Astrophysical Journal; [2006]; Volume 641, pp. 418-426; In English Contract(s)/Grant(s): GO4-5162X; NNG05GA54G; NSERC-228738-03; NSERC-268264-03; Copyright; Avail.: Other Sources
We report on the 2004 June 29 X-ray burst detected from the direction of the AXP 1E 1048.1-5937 using the RXTE. We find a simultaneous increase of approx. 3.5 times the quiescent value in the 2-10 keV pulsed flux of 1E 1048.1-5937 during the tail of the burst, which identifies the AXP as the burst s origin. The burst was overall very similar to the two others reportedfrom the direction of this source in 2001. The unambiguous identification of 1E 1048.1-5937 as the burster here confirms that it was the origin of the 2001 bursts as well. The epoch of the burst peak was very close to the arrival time of 1E 1048.1-5937s pulse peak. The burst exhibited significant spectral evolution, with the trend going from hard to soft. Although the average spectrum of the burst was comparable in hardness (Lambda approx. 1.6) to those,of the 2001 bursts, the peak of this burst was much harder (Lambda approx. 0.3).
During the 11 days following the burst, the AXP was observed further with RXTE, XMM-Newton, and Chandra. Pre- and post-burst observations revealed no change in the total flux or spectrum of the quiescent emission. Comparing all three bursts detected thus far from this source, we find that this event was the most fluent (\g3.3 x 10(exp-8 ergs/sq cm) in the 2-20 keV band), had the highest peak flux (59+/-9 x 10(exp -10)ergs/s/sq cm) in the 2-20 keV band), and had the longest duration (\g699 s). The long duration of the burst differentiates it from SGR bursts, which have typical durations of approx.0.1 s. Bursts that occur preferentially at pulse maximum, have fast rises, and long X-tails containing the majority of the total burst energy have been seen uniquely from AXPs. The marked differences between AXP and SGRs bursts may provide new clues to help understand the physical differences between these objects. Author
Magnetars; X Ray Timing Explorer; X Rays; Spectra
20060016448 Aerospace Corp., El Segundo, CA USA
Pico Satellite Solar Cell Testbed (PSSC Testbed)
Simburger, Edward J; Liu, Simon; Halpine, John; Hinkley, David; Rumsey, Daniel; Yoo, Henry; Jan 2005; 4 pp.; In English; Original contains color illustrations Report No.(s): AD-A443521; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA443521; Avail.: CASI: A01, Hardcopy
The Picosatellite Solar Cell (PSSC) Testbed flight experiment is designed to obtain space environment degradation data for advanced solar cells. The purpose of the first flight (ISS orbit) is to develop and operationally test the picosatellite and associated ground station. Subsequent flights will be in a Geosynchronous Transfer Orbit, which will provide accelerated radiation degradation data for missions to geosynchronous orbit. DTIC
Aerospace Environments; Artificial Satellites; Degradation; Solar Cells; Solar Radiation; Space Flight; Test Stands
20060016483 George Washington Univ., Washington, DC USA
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Production of Lunar Oxygen Through Vacuum Pyrolysis
Matchett, John; Jan 26, 2006; 71 pp.; In English; Original contains color illustrations Report No.(s): AD-A443950; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA443950; Avail.: CASI: A04, Hardcopy
Increasing efficiency of future space exploration will require that missions utilize non-terrestrial resources for propellant manufacture. The vacuum pyrolysis method of oxygen production from lunar regolith presents a viable option for in situ propellant production because of its simple operation involving limited resources from earth.
Lunar regolith, the fine layer of pulverized rock across the entire lunar surface, is composed of approximately forty percent oxygen in the form of metal oxides. Employing concentrated solar radiation to heat raw regolith beyond its respective vaporization temperatures will dissociate the regolith minerals and agglutinates into reduced oxides and gaseous oxygen. Once dissociated, rapid quenching will cause the reduced oxides to condense, releasing gaseous oxygen to be isolated and stored. Vacuum solar pyrolysis experiments involving terrestrial representatives of lunar regolith were completed at temperatures between 1000 degrees Celsius and 2000 degrees Celsius at a rough vacuum. A large Fresnel lens was employed to focus solar radiation on a small sample of regolith simulant,located in a vacuum chamber. Pyrolysis measurement data collected included pressure, temperature, mass loss, residual gas analysis, and scanning electron microscopy.
The complexity of the lunar environment presents new engineering challenges to a terrestrially proven pyrolysis system. The lunar pyrolysis oxygen production plant meets these challenges by a robust design that takes advantage of all the lunar resources. The technology readiness of an oxygen production plant will be demonstrated on an evolutionary path. Oxygen production yields are estimated at 6-23% of regolith mass depending upon oxide dissociation and condenser efficiency. This study provides an analysis of the infrastructure needed for an oxygen production plant through vapor phase pyrolysis on the lunar surface. DTIC
Lunar Environment; Oxygen; Propellants; Pyrolysis; Regolith; Vacuum
20060016646 Physical Sciences, Inc., Andover, MA USA
Scintillator-Based Low-Energy Imaging Particle Spectrometer
Galica, G E; Coxe, R L; Chaves, R G; Spence, H E; Dichter, B K; Cooke, D L; Ginet, G; Apr 2005; 8 pp.; In English; Original contains color illustrations Contract(s)/Grant(s): F19628-01-C-0017 Report No.(s): AD-A444226; PSI-SR-1223; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA444226; Avail.: CASI: A02, Hardcopy
Physical Sciences Inc. (PSI), in cooperation with the Boston University Center for Space Physics, and under the sponsorship of the Air Force Research Laboratory Space Vehicle Directorate, has developed and tested a lightweight, multi-configuration sensor to monitor the space weather environment. The scintillator-based, Low-Energy Imaging Particle Spectrometer (LIPS) is ideally suited to monitoring the lower energy (20 to 2000 keV) charged particle environment responsible for deep dielectric charging. The LIPS design is also compatible with the weight, volume, and power requirements of small satellites (\h1 kg, \h2 W). The LIPS design does not rely upon a magnetic sector to discriminate between particle types; rather it takes advantage of particle cross-section characteristics and scintillator properties to discriminate. We have previously reported on the feasibility demonstration of our approach; i.e., using thin films of materials to create particle-specific detectors, coupled to a position-sensitive photomultiplier tube. We have since developed a fully-functional and calibrated engineering model of LIPS. We are currently preparing LIPS for flight validation as part of the Air Force Research Laboratory (AFRL) Space Weather Experiment (SWx) that will fly as part of the Cygnus flight demonstration program. Herein we report on the engineering model development and calibration of LIPS. DTIC
Aerospace Environments; Imaging Spectrometers; Scintillation; Scintillation Counters; Spectrometers; Weather
20060016673 Air Force Research Lab., Hanscom AFB, MA USA
Reexamination of the Coronal Index of Solar Activity
Rybansky, M; Rusin, V; Minarovjech, M; Klocok, L; Cliver, E W; Aug 25, 2005; 10 pp.; In English Contract(s)/Grant(s): Proj-1010 Report No.(s): AD-A444269; AFRL-VS-HA-TR-2006-1003; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA444269; Avail.: CASI: A02, Hardcopy
The coronal index (CI) of solar activity is the irradiance of the Sun as a star in the coronal green line (Fe XIV, 530.3 nm or 5303 A). It is derived from ground-based observations of the green corona made by the network of coronal stations (currently Kislovodsk, Lomnicky Stit, Norikura, and Sacramento Peak). The CI was introduced by Rybansky (1975) to facilitate comparison of ground-based green line measurements with satellite-based extreme ultraviolet and soft X-ray observations. The CI since 1965 is based on the Lomnicky Stit photometric scale; the CI was extended to earlier years by Rybansky et al. (1994) based on cross-calibrations of Lomnicky Stit data with measurements made at Pic du Midi and Arosa. The resultant 1939-1992 CI had the interesting property that its value at the peak of the 11-year cycle increased more or less monotonically from cycle 18 through cycle 22 even though the peak sunspot number of cycle 20 exhibited a significant local minimum between that of cycles 19 and 21. DTIC
Coronas; Solar Activity; Solar Corona
20060016760 Air Force Research Lab., Hanscom AFB, MA USA
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A Comparison of GPS Performance in a Scintillation Environment at Ascension Island
Groves, K M; Basu, S; Quinn, J M; Pedersen, T R; Falinski, K; Brown, A; Silva, R; Ning, P; Sep 2000; 9 pp.; In English; Original contains color illustrations Report No.(s): AD-A444409; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA444409; Avail.: CASI: A02, Hardcopy
Post-sunset disturbances in the equatorial ionosphere routinely cause rapid phase and amplitude fluctuations (i.e.,scintillation) of radio waves propagating through the disturbed regions. The intensity of scintillations is positively correlated with the solar cycle and the associated signal fades will often exceed 20 dB at L-band frequencies during solar maximum. The effect of such an environment on the performance of GPS navigation systems is poorly understood. In March 2000 AFRL conducted a campaign at Ascension Island to test the performance of several GPS receivers under potentially severe scintillation conditions. Ascension Island is located at approximately 16 S magnetic latitude, a region of intense ionospheric disturbances. The systems tested included a Plessey GPS Builder, a Novatel-based prototype GPS Silicon Valley (GSV) Ionospheric Scintillation Monitor (ISM) modified specifically for scintillation applications, a custom High Gain Advanced GPS Receiver (HAGR) developed for AFRL by NAVSYS Corporation and an Ashtech Z-12. Overall, the Ashtech proved to be very robust at tracking the carrier signal amplitude and phase, but it experienced scintillation-induced navigation outages on four of the eight nights of observations. The responses of the different receivers during severe scintillation varied significantly, suggesting that models to simulate ionospheric effects on GPS performance must be receiver-specific. DTIC
Global Positioning System; Islands; Scintillation; Solar Cycles
20060017069 NASA Ames Research Center, Moffett Field, CA, USA
Steps Toward Identifying PAHs: A Child's Garden of Recent Results
Hudgins, Douglas M.; [2005]; 1 pp.; In English; IAU Symposium 231 Astrochemistry Throughout the Universe: Recent Successes and Current challenges, 29 Aug. - 2 Sept. 2005, Pacific Grove, CA, USA Contract(s)/Grant(s): 21-344-58-3H; Copyright; Avail.: Other Sources; Abstract Only
Based on over two decades of experimental, observational and theoretical studies by scientists around the world. It is nowwidely accepted that the composite emission of mixtures of vibrationally-excited PAHs and PAH ions can accommodate thegeneral pattern of band positions, intensities, and profiles observed in the discreet IR emission features of carbon-rich interstellar dust, as well as the variations in those characteristics. These variations provide insight into the detailed nature of the emitting PAH population and reflect conditions within the emitting regions giving the population enormous potential as probes of astrophysical environments. Moreover, the ubiquity and abundance of this material has impacts that extend well beyond the IR. In this presentation we will examine recent, combined experimental, theoretical, and observational studies that indicate that nitrogen-substituted PAHs represent an important component of the interstellar dust population, and we will go on to explore some of the ramifications of this result. We will also explore the results of recent experimental studies of the strong, low-lying electronic transitions of ionized PAH ions in the Near-IR (0.7 - 2.5 microns) and explore the role that these transitions might play in pumping the PAH IR emission in regions of low-excitation. Author
Polycyclic Aromatic Hydrocarbons; Interstellar Matter; Near Infrared Radiation; Cosmic Dust; Ions; Composite Materials; Carbon
20060018340 Academia Sinica, Shanghai, China
Annals of Shanghai Observatory, Academia Sinica, Volume 26
Hu, Xiaogong, Editor; Zheng,Weimin, Editor; Shao, Zhengyi, Editor; Wan, Ningshan, Editor; 2005; 138 pp.; In English; See also 20060018341 - 20060018352; Original contains black and white illustrations; Copyright; Avail.: Other Sources Topics covered include: Estimations of vertical deformation rates of VLBI stations by constraints of rates of baseline length change; Long-term effects of lunar gravity on low lunar orbit; Imaging processing for spaceborne synthetic aperture radar; Numerical solution of the distributed equation of the wind Field with respect to height in Ekman layer; Assimilation of bending angle from GPS radio occultation in symmetrical model; A Proper Motion Study for Stars in the Region of the Open Cluster NGC2244; Proper Motions and Membership Probabilities of Stars in the Region of the Open Cluster NGC6530; Pumping Efficiency of OH Megamaser; Realization of Linear-Circular Polarization Conversion with the ADS; A FORTRAN Realization of the Block Adjustment of CCD Frames; The introduction to FITSIO and its applied example; and An XML-based method for astronomy software designing. Derived from text
Very Long Base Interferometry; Synthetic Aperture Radar; Imaging Techniques; Interstellar Masers; Global Positioning System; Gravitational Effects; Linear Polarization; Lunar Gravitation; Open Clusters; Assimilation
20060018341 Shanghai Astronomical Observatory, China
Long-term Effects of Lunar Gravity on Low Orbit
Huang, Yong; Hu, Xiaogong; Huang, Cheng; Annals of Shanghai Observatory, Academia Sinica, Volume 26; 2005, pp. 21-30; In Chinese; See also 20060018340; Copyright; Avail.: Other Sources
In this paper, the long-term effects of lunar gravity(zonal terms) on low lunar orbit are investigated. The analytical solution are applied to high degree and order lunar gravity field model (JGL165Pl). To decrease the computing errors, using the recurrence formulas to calculate inclination functions. The results show that it is not possible to exist fdr a polar frozen orbit at 100km altitude; however, frozen orbits are possible at higher altitude or inclination around 90 degrees. Results for period orbits show that the eccentricity grows too large before completing a period for a initial polar orbit at l00km altitude. For a initial polar orbit at 200km altitude, the satellite will complete the period. The results are validated by the numerical calculation using the software GEODYN. Author
Lunar Gravitation; Lunar Orbits; Gravitational Effects
20060018342 Shanghai Astronomical Observatory, China
Pumping Efficiency of OH Megamaser
Yu, Zhiyao; Annals of Shanghai Observatory, Academia Sinica, Volume 26; 2005, pp. 102-109; In Chinese; See also 20060018340; Copyright; Avail.: Other Sources
So far 106 OH megamaser sources have been found. The classical OH megamaser model shows that the unsaturated OH megamaser is pumped by the intense far-infrared radiation from the host galaxies. The pumping efficiency (S1667/S60) is a very important physical parameter for the unsaturated OH megamaser and their host galaxies. This paper studies what is related with the pumping efficiency. This paper obtains that both L(sub OH) nd S1667 correlated with (S1667/S60); but all of Rh [- tau] (OH1667MHz), and S1665 are not correlated with log(S1667/S60), respectively. Author
Galaxies; Hydroxyl Emission; Interstellar Masers
20060018343 Shanghai Astronomical Observatory, China
Numerical Solution of the Distributed Equation of the Wind Field with Respect to Height in Ekman Layer
Liu, Min; Guo, Peng; Annals of Shanghai Observatory, Academia Sinica, Volume 26; 2005, pp. 38-46; In Chinese; See also 20060018340; Copyright; Avail.: Other Sources
The distributed equation of the wind field with respect to height in Ekman layer has been deduced from the atmospheric horizontal motion equation. This equation is expressed by a 2-order linear differential equation. Numerical solution of 2-order linear differential equation with boundary condition is given by finite difference method. Computation simulation results are given in this paper. A brief analysis of the vertical distribution of the wind in Ekman layer can be found in the discussion. Author
Ekman Layer; Atmospheric Circulation; Boundary Conditions; Differential Equations; Wind Velocity; Finite Difference Theory; Equations of Motion; Velocity Distribution
20060018344 Academia Sinica, Urumqi, China
An XML-based Method for Astronomy Software Designing
Liao, Migxue; Aili, Yusupu; Zhang, Jin; Annals of Shanghai Observatory, Academia Sinica, Volume 26; 2005, pp. 132; In English; See also 20060018340; Copyright; Avail.: Other Sources
XML-based method for standardization of software designing is introduced and analyzed and successfully applied to renovating the hardware and software of the digital clock at Urumqi Astronomical Station. Basic strategy for eliciting time information from the new digital clock of FT206 in the antenna control program is introduced. By FT206, the need to compute how many centuries passed since a certain day with sophisticated formulas is eliminated and it is no longer necessary to set right UT time for the computer holding control over antenna because the information about year, month, day are all deduced from Julian day dwelling in FT206, rather than from computer time. With XML-based method and standard for software designing, various existing designing methods are unified, communications and collaborations between developers are facilitated , and thus Internet-based mode of developing software becomes possible. The trend of development of XML-based designing method is predicted. Author
Document Markup Languages; Numerical Control; Computers; Astronomy; Computer Programs
20060018345 Shanghai Astronomical Observatory, China
A Proper Motion Study for Stars in the Region of the Open Cluster NGC2244
Gao, Jianyun; Chen, Li; Wang, Jiaji; Annals of Shanghai Observatory, Academia Sinica, Volume 26; 2005, pp. 78-94; In Chinese; See also 20060018340; Copyright; Avail.: Other Sources
By measuring the plate data of Shanghai Astronomical Observatory absolute proper motions of 495 stars in the region of 55' x 55' around open cluster NGC2244 are determined referred to 78 stars in the Tycho-2 Catalogue. The reduction, results and accuracies of proper motion determination are discussed and analyzed in detail. Author
Astronomical Observatories; Catalogs (Publications); Open Clusters
20060018346 Shanghai Astronomical Observatory, China
Proper Motions and Membership Probabilities of Stars in the Region of the Open Cluster NGC6530
Wen, Wen; Zhao, Junliang; Chen, Li; Annals of Shanghai Observatory, Academia Sinica, Volume 26; 2005, pp. 94-102; In Chinese; See also 20060018340; Copyright; Avail.: Other Sources
By using the plate data of Shanghai Astronomical Observatory, which were taken with the 40cm astrograph of focal length 6.9m at Z^o-S^e, proper motions and membership probabilities of 364 stars in the region of the open cluster NGC6530 are determined. The 79 stars of the Tycho-2 Catalogue found in the cluster region are used as reference stars for central overlap reduction of stellar proper motions. The procedure, results and accuracies of proper motion determination are discussed and analyzed in some detail. The maximum epoch difference of the 6 photographic plates used for proper motion reduction is 87 years, and the mean error of the proper motions for these stars we obtained is estimated to be. Finally, a list of proper motions and membership probabilities of 364 stars in the region of the NGC6530 is given. Author
Stellar Motions; Astronomical Observatories; Astrography; Catalogs (Publications); Open Clusters
20060018348 Shanghai Astronomical Observatory, China
Imaging Processing for Spaceborne Synthetic Aperture Radar
Chen, Yanling; Annals of Shanghai Observatory, Academia Sinica, Volume 26; 2005, pp. 30-38; In Chinese; See also 20060018340; Copyright; Avail.: Other Sources
Synthetic Aperture Radar (SAR) is currently a hot research topic in the field of technique of Microwave Remote Sensing. Compared with the other sensors , SAR possesses many incomparable advantages such as the capability to work at all-time and under all weather, high spatial resolution and strong penetrability through the ground surface. Thus, it has acquired widespread applications. Imaging processing is the core part of SAR technique. This paper first analyzes the echoes signal model of point target and several commonly used SAR imaging algorithms. And then , using Range-Doppler algorithm as an example, this paper illustrates the essential of range compressing and azimuth compressing, discusses in detail the key problems such as Doppler parameters estimation, range migration correction and speckle noise elimination etc. Finally, this paper gives an imaging example using ERS-1/SAR raw data, followed by a simple summary of the SAR imaging technique. Author
Imaging Techniques; Image Processing; Remote Sensing; Synthetic Aperture Radar; Spatial Resolution; Microwave Imagery
20060018349 Shanghai Astronomical Observatory, China
A FORTRAN Realization of the Block Adjustment of CCD Frames
Yu, Yong; Tang, Zhenghong; Li, Jinling; Zhao, Ming; Annals of Shanghai Observatory, Academia Sinica, Volume 26; 2005, pp. 118-124; In Chinese; See also 20060018340; Copyright; Avail.: Other Sources
A FORTRAN version realization of the block adjustment (BA) of overlapping CCD frames is developed. The flowchart is introduced including (a) data collection, (b) preprocessing, and (c) BA and object positioning. The subroutines and their functions are also demonstrated. The program package is tested by simulated data with/without the application of white noises. It is also preliminarily applied to the reduction of optical positions of four extragalactic radio sources. The results show that because of the increase in the sky coverage and number of reference stars, the precision of deducted positions is improved compared with single plate adjustment. Author
Fortran; Charge Coupled Devices; Data Acquisition; Extragalactic Radio Sources; Reference Stars; Precision
20060018350 Shanghai Astronomical Observatory, China
Estimations of Vertical Deformation Rates of VLBI Stations by Constraints of Rates of Baseline Length Change
Yang, Zhigen; Zhu, Yaozhong; Annals of Shanghai Observatory, Academia Sinica, Volume 26; 2005, pp. 13-21; In Chinese; See also 20060018340; Copyright; Avail.: Other Sources
International terrestrial reference frame (ITRF) solutions, such as ITRF2000, are combination solutions using different space geodetic techniques and could have potential 'inconsistencies' between various realizations. At present, the estimated average uncertainty on regularly observed baselines for change of the VLBI baseline length is better than 1.0 mm/a. Based on the 3-dimensional velocity vectors of VLBI stations in ITRF2000 and the earth's plate motion model NNR-NUVEL-1A, the local/regional deformation rates of eight VLBI stations are estimated using the observed rates of change of VLBI baseline lengths as parameter constraints. Comparisons of the results with those of the ITRFs solutions and GLB2003, VTRF2003, VTRF2005 solutions (Nothnagel, 2003, 2005) are completed. The observed baseline rates as constraints are adopted in this paper and the possible deformations at a local/regional spatial scale, for isolating the potential 'inconsistencies' from the TRF solutions, are addressed for the accurately realization and maintenance of ITRF.
AuthorVery Long Base Interferometry; Deformation; Estimating; Coordinates
20060018351 Shanghai Astronomical Observatory, China
The Introduction to FITSIO and Its Applied Example
Li, Huanan; Xiao, Quanbao; Shao, Zhengyi; Annals of Shanghai Observatory, Academia Sinica, Volume 26; 2005, pp. 124-131; In Chinese; See also 20060018340; Copyright; Avail.: Other Sources
FITSIO package, mainly used to deal with FITS data, is introduced in this paper. By using subroutines in FITSIO, SDSS images of NGC4044 and NGC5227 in g, r, i bands are rebuilt after matching their pixels in a common celestial coordinate system. Then, RGB images of these 2 galaxies, as well as their color distributions are plotted, which clearly showed the color variation of stellar components depending on their locations. Author
Coordinates; Celestial Geodesy; Position (Location); Stars; Galaxies
20060018352 Shanghai Astronomical Observatory, China
Realization of Linear-Circular Polarization Conversion with the ADS
Chen, Songlin; Annals of Shanghai Observatory, Academia Sinica, Volume 26; 2005, pp. 109-118; In Chinese; See also 20060018340; Copyright; Avail.: Other Sources
A Solution to realize linear-circular polarization conversion for a C band dual-circular polarized low noise receiver is presented in this paper, and the relationship between the transmission balance of the linear channels and the polarizationconversion is studied. This paper also analyzes how to compensate the phase unbalance by tuning the length difference o f a pair of coaxial cables, and introduces the steps to realize the conversion with ADS software. The linear-circular polarization conversion is realized and the separation between LHC and RHC is better than 20dB. Author
Linear Polarization; Circular Polarization; C Band; Low Noise; Receivers
20060018393 NASA Ames Research Center, Moffett Field, CA, USA
Observations and Laboratory Data of Planetary Organics
Roush, Ted L.; [2002]; 1 pp.; In English; No Copyright; Avail.: Other Sources; Abstract Only
Many efforts are underway to search for evidence of prebiotic materials in the outer solar system. Current and planned Mars missions obtain remote sensing observations that can be used to address the potential presence of prebiotic materials. Additional missions to, and continuing earth-based observations of, more distant solar system objects will also provide remote sensing observations that can be used to address the potential presence of prebiotic materials. I will present an overview of on-going observations, associated laboratory investigations of candidate materials, and theoretical modeling of observational data. In the past the room temperature reflectance spectra of many residues created from HC-bearing gases and solids have been reported. The results of an investigation of what effect temperatures more representative of outer solar system surfaces (50-140K) have on the reflectance spectra of these residues, and the associated interpretations, will be presented. The relatively organic-rich Tagish Lake Meteorite has been suggested as a spectral analog for Dtype asteroids. Using a new approach that relies upon iterative use of Hapke theory and Kraniers-Kronig analysis the optical constants of TLM were estimated. The approach and results of the analysis will be presented. Use of optical constants in scattering theories, such as the Hapke theory, provide the ability to determine quantitative estimates of the relative abundances and grain sizes of candidate surface components. This approach has been applied to interpret the reflectance spectra of several outer solar system surfaces. A summary will be provided describing the results of such modeling efforts. Author
Meteorites; Gas Giant Planets; Remote Sensing; Reflectance; Physical Optics; Optical Properties; Mars Missions; Asteroids
20060019091 California Univ., Lawrence Berkeley National Lab., Berkeley, CA, USA
UV Spectroscopy of Type Ia Supernovae at Low- and High-Redshift
Nugent, P.; January 2005; 10 pp.; In English Report No.(s): DE2006-860915; No Copyright; Avail.: Department of Energy Information Bridge
In the past three years two separate programs were initiated to study the restframe UV properties of Type Ia Supernovae. The low-redshift study was carried out using several ground-based facilities coupled with HST/STIS observations. The high-redshift program is an offshoot of the CFHT Legacy Survey and uses Keck/LRIS to obtain spectra. Here we present the preliminary results from each program and their implications for current cosmology measurements. NTIS
Cosmology; Red Shift; Supernovae; Ultraviolet Spectroscopy
20060019191 NASA Ames Research Center, Moffett Field, CA, USA
From Astrochemistry to Astrobiology
Allamandola, L. J.; [2005]; 1 pp.; In English; Astrochemistry Seminar, 25-29 Oct. 2005, IL, USA; No Copyright; Avail.: Other Sources; Abstract Only
Tremendous strides have been made in our understanding of interstellar material over the past twenty five years thanks to significant developments in observational astronomy and laboratory astrophysics. Twenty years ago the composition of interstellar dust was largely guessed at, the concept of ices in dense molecular clouds ignored, and the notion of large, abundant, gas phase, carbon-rich molecules widespread throughout the interstellar medium (ISM) considered impossible. Today the composition of interstellar dust is reasonably well understood. In molecular clouds, the birthplace of stars and planets, these cold dust particles are coated with mixed molecular ices whose composition is very well constrained. Lastly, the signature of carbon-rich polycyclic aromatic hydrocarbons (PAHs), shockingly large molecules by early interstellar chemistry standards, is widespread throughout the Universe. The first part of this talk will describe how infrared spectroscopic studies of interstellar space, combined with laboratory simulations of interstellar ice chemistry, have revealed the widespread presence of interstellar PAHs and the composition of interstellar ices, the building blocks of comets. The remainder of the presentation will focus on the photochemical evolution of these materials and astrobiology. Within a molecular cloud, and especially the presolar nebula, materials frozen into the ices are photoprocessed by ultraviolet light and produce more complex molecules. As these materials are the building blocks of comets and related to carbonaceous micrometeorites, they are likely to have been important sources of complex materials delivered to the early Earth and their composition may be related to the origin of life. Author
Interstellar Chemistry; Polycyclic Aromatic Hydrocarbons; Biological Evolution; Cosmic Dust; Exobiology; Vapor Phases; Ultraviolet Radiation; Molecular Clouds; Laboratory Astrophysics
Source: NASA
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