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Sample records for ablation program titan

  1. Titan!

    NASA Astrophysics Data System (ADS)

    Matson, Dennis L.

    2010-05-01

    Cassini-Huygens achieved Saturnian orbit on July 1, 2004. The first order of business was the safe delivery of the Huygens atmospheric probe to Titan that took place on January 14, 2005. Huygens descended under parachute obtaining observations all the way down to a safe landing. It revealed Titan for the first time. Stunning are the similarities between Titan and the Earth. Viewing the lakes and seas, the fluvial terrain, the sand dunes and other features through the hazy, nitrogen atmosphere, brings to mind the geological processes that created analogous features on the Earth. On Titan frozen water plays the geological role of rock; liquid methane takes the role of terrestrial water. The atmospheres of both Earth and Titan are predominately nitrogen gas. Titan's atmosphere contains 1.5% methane and no oxygen. The surface pressure on Titan is 1.5 times the Earth's. There are aerosol layers and clouds that come and go. Now, as Saturn proceeds along its solar orbit, the seasons are changing. The effects upon the transport of methane are starting to be seen. A large lake in the South Polar Region seems to be filling more as winter onsets. Will the size and number of the lakes in the South grow during winter? Will the northern lakes and seas diminish or dry up as northern summer progresses? How will the atmospheric circulation change? Much work remains not only for Cassini but also for future missions. Titan has many different environments to explore. These require more capable instruments and in situ probes. This work was conducted at the Jet Propulsion Laboratory, California Institute of Technology under contract with the National Aeronautics and Space Administration.

  2. Midterm Summary of Japan-US Fusion Cooperation Program TITAN

    SciTech Connect

    Muroga, Takeo; Sze, Dai-Kai; Sokolov, Mikhail; Katoh, Yutai; Stoller, Roger E

    2011-01-01

    Japan-US cooperation program TITAN (Tritium, Irradiation and Thermofluid for America and Nippon) started in April 2007 as 6-year project. This is the summary report at the midterm of the project. Historical overview of the Japan-US cooperation programs and direction of the TITAN project in its second half are presented in addition to the technical highlights. Blankets are component systems whose principal functions are extraction of heat and tritium. Thus it is crucial to clarify the potentiality for controlling heat and tritium flow throughout the first wall, blanket and out-of-vessel recovery systems. The TITAN project continues the JUPITER-II activity but extends its scope including the first wall and the recovery systems with the title of 'Tritium and thermofluid control for magnetic and inertial confinement systems'. The objective of the program is to clarify the mechanisms of tritium and heat transfer throughout the first-wall, the blanket and the heat/tritium recovery systems under specific conditions to fusion such as irradiation, high heat flux, circulation and high magnetic fields. Based on integrated models, the breeding, transfer, inventory of tritium and heat extraction properties will be evaluated for some representative liquid breeder blankets and the necessary database will be obtained for focused research in the future.

  3. TITAN 2 Reliability and Aging Surveillance Program (RASP)

    NASA Astrophysics Data System (ADS)

    Littleton, J. M.

    1982-02-01

    This report provides the results of RASP Phase I and Phase IA testing as completed for Missile Airborne and Ground Support Systems. The Phase I testing is conducted in conjunction with the missile recycle and removal of the engines for testing under the Service Life Analysis Program (SLAP), and includes special and critical testing of all airborne and ground support equipment for aging trends. Phase IA testing does not involve Recycle, SLAP Testing or Downloading of Propellants, but includes testing of all critical airborne and support equipment for launch readiness verification, aging trends, logistic support, special testing or inspection requirements. The data collected during RASP testing are reduced, analyzed and applied to the Titan II Weapon System Mathematical Model to produce estimates of system reliability. The actual system reliability estimates obtained are reported in the OO-ALC System Effectiveness Report (RCS LOG-MM(Q)7372).

  4. Thermal Response and Ablation Programs for TPS Sizing Computation

    NASA Technical Reports Server (NTRS)

    Chen, Y. K.; Rasky, Daniel J. (Technical Monitor)

    1997-01-01

    The computer programs developed at NASA Ames Research Center for TPS sizing computation have been applied to many NASA's space missions, such as Mars Pathfinder, StarDust, Mars 2001, DS-II, and Saturn Entry Probe. These computer programs include FIAT (Fully Implicit Ablation and Thermal Response Program, MAT (Multi-component Ablation Thermochemistry Program), TPSX (Thermal Protection Systems Expert & Material Properties Database), and TPSGui (Thermal Protection Systems Graphical User Interface). For most planetary missions, the aerothermodynamics and material response are strongly coupled; thus a closed loop iteration technique between the FIAT and CFD (Computational Fluid Dynamics) codes has been developed to obtain the high fidelity bench mark TPS sizing solution. The computer codes and predictive methods are presented and discussed in detail.

  5. Ablation, Thermal Response, and Chemistry Program for Analysis of Thermal Protection Systems

    NASA Technical Reports Server (NTRS)

    Milos, Frank S.; Chen, Yih-Kanq

    2010-01-01

    In previous work, the authors documented the Multicomponent Ablation Thermochemistry (MAT) and Fully Implicit Ablation and Thermal response (FIAT) programs. In this work, key features from MAT and FIAT were combined to create the new Fully Implicit Ablation, Thermal response, and Chemistry (FIATC) program. FIATC is fully compatible with FIAT (version 2.5) but has expanded capabilities to compute the multispecies surface chemistry and ablation rate as part of the surface energy balance. This new methodology eliminates B' tables, provides blown species fractions as a function of time, and enables calculations that would otherwise be impractical (e.g. 4+ dimensional tables) such as pyrolysis and ablation with kinetic rates or unequal diffusion coefficients. Equations and solution procedures are presented, then representative calculations of equilibrium and finite-rate ablation in flight and ground-test environments are discussed.

  6. 1-D Transient Thermal Modeling of an Ablative Material (MCC-1) Exposed to a Simulated Convective Titan 4 Launch Environment

    NASA Technical Reports Server (NTRS)

    Reinarts, Thomas R.; Crain, William K.; Stuckey, C. Irvin; Palko, Richard L.

    1998-01-01

    The purpose of the work is to demonstrate that the flat test panel substrate temperatures are consistent with analysis predictions for MCC-1 applied to a aluminum substrate. The testing was performed in an aerothermal facility on samples of three different thicknesses of MCC-1 on an aluminum substrate. The results of the test were compared with a Transient Thermal model. The key assumptions of the Transient Thermal model were: (1) a one-dimensional heat transfer; (2) a constant ablation recession rate (determined from pre and post-test measurements); (3) ablation temperature of 540 degrees F; (4) Char left behind the ablation front; and (5) temperature jump correction for incident heat transfer coefficient. Two methods were used to model the heating of bare MCC-1: (1) Directly input surface temperature as a function of time; and (2) Aerothermal heating using calibration plate data and subtracting the radiation losses to tunnel walls. The results are presented as graphs. This article is presented in Viewgraph format.

  7. Endometrial ablation

    MedlinePlus

    Hysteroscopy-endometrial ablation; Laser thermal ablation; Endometrial ablation-radiofrequency; Endometrial ablation-thermal balloon ablation; Rollerball ablation; Hydrothermal ablation; Novasure ablation

  8. Titan Saturn System Mission

    NASA Technical Reports Server (NTRS)

    Reh, Kim R.

    2009-01-01

    Titan is a high priority for exploration, as recommended by NASA's 2006 Solar System Exploration (SSE) Roadmap. NASA's 2003 National Research Council (NRC) Decadal Survey and ESA's Cosmic Vision Program Themes. Recent revolutionary Cassini-Huygens discoveries have dramatically escalated interest in Titan as the next scientific target in the outer solar system. This study demonstrates that an exciting Titan Saturn System Mission (TSSM) that explores two worlds of intense astrobiological interest can be initiated now as a single NASA/ESA collaboration.

  9. Simulation of Pyroclastic Flows of Colima Volcano, Mexico, Using the TITAN2D Program

    NASA Astrophysics Data System (ADS)

    Rupp, B.; Bursik, M.; Patra, A.; Pitman, B.; Bauer, A.; Nichita, C.; Saucedo, R.; Macias, J.

    2003-04-01

    A new numerical code for simulating granular avalanches, TITAN2D, was used to model block-and-ash flows from the 1991-1999 eruptions of Colima Volcano, Mexico. The block-and-ash flows were simulated on a gridded Digital Elevation Model(DEM), which was prepared and imported using a standard GIS function library (GRASS). The TITAN2D program is based upon a model for an incompressible Coulomb continuum, a 'shallow-water' granular flow. The conservation equations for mass and momentum are solved with a Coulomb-type friction term at the interface between the granular material and the basal surface. It is assumed that conservation of energy can be neglected to first order because the coarse grain size typical of the basal avalanche results in minimal thermal effects on avalanche propagation. The resulting hyperbolic system of equations is solved using a parallel, adaptive mesh, Godunov scheme. The Message Passing Interface (MPI) API allows for computing on multiple processors, which increases computational power, decreases computing time, and allows the use of large data sets. Adaptive gridding allows for the concentration of computing power on regions of special interest. Mesh refinement captures the leading edge of the avalanche, as well as locations where the topography changes rapidly. Mesh unrefinement is applied where solution values are relatively constant or small. There were thousands of rockfalls and numerous block-and-ash flows during the 1991-1999 eruptions of Colima Volcano, with volumes ranging from a few cubic meters to 10^6 m^3. We have records of numerous flows, which include volume, run out distance, deposit area, and in some cases a videotape record of flow propagation. The flows originated from a vent plugging dome, lava flows or minor column collapse. All flows followed cross-slope concavities on the upper edifice, and channels or relative topographic lows on the lower edifice. The flows propagated for distances up to 4 km from the source. We are

  10. CHAP III- CHARRING ABLATOR PROGRAM FOR ADVANCED INVESTIGATION OF THERMAL PROTECTION SYSTEMS FOR ENTRY

    NASA Technical Reports Server (NTRS)

    Stroud, C. W.

    1994-01-01

    The transient response of a thermal protection material to heat applied to the surface can be calculated using the CHAP III computer program. CHAP III can be used to analyze pyrolysis gas chemical kinetics in detail and examine pyrolysis reactions-indepth. The analysis includes the deposition of solid products produced by chemical reactions in the gas phase. CHAP III uses a modelling technique which can approximate a wide range of ablation problems. The energy equation used in CHAP III incorporates pyrolysis (both solid and gas reactions), convection, conduction, storage, work, kinetic energy, and viscous dissipation. The chemically reacting components of the solid are allowed to vary as a function of position and time. CHAP III employs a finite difference method to approximate the energy equations. Input values include specific heat, thermal conductivity, thermocouple locations, enthalpy, heating rates, and a description of the chemical reactions expected. The output tabulates the temperature at locations throughout the ablator, gas flow within the solid, density of the solid, weight of pyrolysis gases, and rate of carbon deposition. A sample case is included, which analyzes an ablator material containing several pyrolysis reactions subjected to an environment typical of entry at lunar return velocity. CHAP III is written in FORTRAN IV for batch execution and has been implemented on a CDC CYBER 170 series computer operating under NOS with a central memory requirement of approximately 102K (octal) of 60 bit words. This program was developed in 1985.

  11. Effect of Surface Nonequilibrium Thermochemistry in Simulation of Carbon Based Ablators

    NASA Technical Reports Server (NTRS)

    Chen, Yih-Kang; Gokcen, Tahir

    2012-01-01

    This study demonstrates that coupling of a material thermal response code and a flow solver using finite-rate gas/surface interaction model provides time-accurate solutions for multidimensional ablation of carbon based charring ablators. The material thermal response code used in this study is the Two-dimensional Implicit Thermal Response and Ablation Program (TITAN), which predicts charring material thermal response and shape change on hypersonic space vehicles. Its governing equations include total energy balance, pyrolysis gas momentum conservation, and a three-component decomposition model. The flow code solves the reacting Navier-Stokes equations using Data Parallel Line Relaxation (DPLR) method. Loose coupling between material response and flow codes is performed by solving the surface mass balance in DPLR and the surface energy balance in TITAN. Thus, the material surface recession is predicted by finite-rate gas/surface interaction boundary conditions implemented in DPLR, and the surface temperature and pyrolysis gas injection rate are computed in TITAN. Two sets of gas/surface interaction chemistry between air and carbon surface developed by Park and Zhluktov, respectively, are studied. Coupled fluid-material response analyses of stagnation tests conducted in NASA Ames Research Center arc-jet facilities are considered. The ablating material used in these arc-jet tests was a Phenolic Impregnated Carbon Ablator (PICA). Computational predictions of in-depth material thermal response and surface recession are compared with the experimental measurements for stagnation cold wall heat flux ranging from 107 to 1100 Watts per square centimeter.

  12. Titan Casts Revealing Shadow

    NASA Astrophysics Data System (ADS)

    2004-05-01

    A rare celestial event was captured by NASA's Chandra X-ray Observatory as Titan -- Saturn's largest moon and the only moon in the Solar System with a thick atmosphere -- crossed in front of the X-ray bright Crab Nebula. The X-ray shadow cast by Titan allowed astronomers to make the first X-ray measurement of the extent of its atmosphere. On January 5, 2003, Titan transited the Crab Nebula, the remnant of a supernova explosion that was observed to occur in the year 1054. Although Saturn and Titan pass within a few degrees of the Crab Nebula every 30 years, they rarely pass directly in front of it. "This may have been the first transit of the Crab Nebula by Titan since the birth of the Crab Nebula," said Koji Mori of Pennsylvania State University in University Park, and lead author on an Astrophysical Journal paper describing these results. "The next similar conjunction will take place in the year 2267, so this was truly a once in a lifetime event." Animation of Titan's Shadow on Crab Nebula Animation of Titan's Shadow on Crab Nebula Chandra's observation revealed that the diameter of the X-ray shadow cast by Titan was larger than the diameter of its solid surface. The difference in diameters gives a measurement of about 550 miles (880 kilometers) for the height of the X-ray absorbing region of Titan's atmosphere. The extent of the upper atmosphere is consistent with, or slightly (10-15%) larger, than that implied by Voyager I observations made at radio, infrared, and ultraviolet wavelengths in 1980. "Saturn was about 5% closer to the Sun in 2003, so increased solar heating of Titan may account for some of this atmospheric expansion," said Hiroshi Tsunemi of Osaka University in Japan, one of the coauthors on the paper. The X-ray brightness and extent of the Crab Nebula made it possible to study the tiny X-ray shadow cast by Titan during its transit. By using Chandra to precisely track Titan's position, astronomers were able to measure a shadow one arcsecond in

  13. Automated generation of NC part programs for excimer laser ablation micromachining from known 3D surfaces

    NASA Astrophysics Data System (ADS)

    Mutapcic, Emir; Iovenitti, Pio G.; Hayes, Jason P.

    2002-11-01

    The purpose of this research project is to improve the capability of the laser micromachinning process, so that any desired 3D surface can be produced by taking the 3D information from a CAD system and automatically generating the NC part programs. In addition, surface quality should be able to be controlled by specifying optimised parameters. This paper presents the algorithms and a software system, which processes 3D geometry in an STL file format from a CAD system and produces the NC part program to mill the surface using the Excimer laser ablation process. Simple structures are used to demonstrate the prototype system's part programming capabilities, and an actual surface is machined.

  14. Graphite Ablation and Thermal Response Simulation Under Arc-Jet Flow Conditions

    NASA Technical Reports Server (NTRS)

    Chen, Y.-K.; Milos, F. S.; Reda, D. C.; Stewart, D. A.; Venkatapathy, Ethiraj (Technical Monitor)

    2002-01-01

    The Two-dimensional Implicit Thermal Response and Ablation program, TITAN, was developed and integrated with a Navier-Stokes solver, GIANTS, for multidimensional ablation and shape change simulation of thermal protection systems in hypersonic flow environments. The governing equations in both codes are demoralized using the same finite-volume approximation with a general body-fitted coordinate system. Time-dependent solutions are achieved by an implicit time marching technique using Gauess-Siedel line relaxation with alternating sweeps. As the first part of a code validation study, this paper compares TITAN-GIANTS predictions with thermal response and recession data obtained from arc-jet tests recently conducted in the Interaction Heating Facility (IHF) at NASA Ames Research Center. The test models are graphite sphere-cones. Graphite was selected as a test material to minimize the uncertainties from material properties. Recession and thermal response data were obtained from two separate arc-jet test series. The first series was at a heat flux where graphite ablation is mainly due to sublimation, and the second series was at a relatively low heat flux where recession is the result of diffusion-controlled oxidation. Ablation and thermal response solutions for both sets of conditions, as calculated by TITAN-GIANTS, are presented and discussed in detail. Predicted shape change and temperature histories generally agree well with the data obtained from the arc-jet tests.

  15. SETUP, a program of representative laboratory simulations of Titan's atmosphere dedicated to better understand and quantify its chemical evolution pathways

    NASA Astrophysics Data System (ADS)

    Gazeau, M.; Bahrini, C.; Benilan, Y.; Jolly, A.; Landsheere, X.; Lebert, B.

    2013-12-01

    Atmospheres are enormously complex systems. Therefore, experimental simulations are a welcome tool in the researcher's toolbox since they provide an alternative source to compare with direct measurements and theoretical models. This is important for Titan, since direct measurements are limited and theoretical models often lack important parameters. The advantage of experimental simulations is that they reduce the problem to only the chemical reactions in a certain region by neglecting atmospheric dynamics. The experimental simulations of Titan's atmosphere performed in the frame of the SETUP (French acronym for Experimental and Theoretical Simulations Useful for Planetology) program are the most representative ever achieved towards Titan's condition in term of energy deposition: the coupled N2/CH4 chemistry is initiated in a flow reactor using microwave plasma discharge as well as Ly-alpha photons delivered by a continuous H2/He lamp. The vacuum pumping and measurement system limit the experiment to pressures above 1x10-3 mbar, which corresponds well to the lower thermosphere and below. The experiment is run at ambient temperature which does not correspond directly with any region, however the upper stratosphere and above is the closest match. According to pressure and temperature, SETUP best represents from the upper stratosphere up to the lower thermosphere. The ability to perform in-situ and absolute analysis is another improvement of SETUP over its predecessors: the chemical composition is probed in-situ using cavity ring-down spectroscopy (CRDS, an absolute and highly sensitive laser spectroscopic technique based upon absorption spectroscopy) allowing us to study the evolution of the resulting gas sample. We have chosen to use a difference-frequency generation technique that combines the advantages of decent sensitivity over widely tunable wavelength range in the mid-infrared region. Indeed, numerous molecular species exhibit their fundamental vibrational

  16. Titan as the Abode of Life.

    PubMed

    McKay, Christopher P

    2016-01-01

    Titan is the only world we know, other than Earth, that has a liquid on its surface. It also has a thick atmosphere composed of nitrogen and methane with a thick organic haze. There are lakes, rain, and clouds of methane and ethane. Here, we address the question of carbon-based life living in Titan liquids. Photochemically produced organics, particularly acetylene, in Titan's atmosphere could be a source of biological energy when reacted with atmospheric hydrogen. Light levels on the surface of Titan are more than adequate for photosynthesis, but the biochemical limitations due to the few elements available in the environment may lead only to simple ecosystems that only consume atmospheric nutrients. Life on Titan may make use of the trace metals and other inorganic elements produced by meteorites as they ablate in its atmosphere. It is conceivable that H₂O molecules on Titan could be used in a biochemistry that is rooted in hydrogen bonds in a way that metals are used in enzymes by life on Earth. Previous theoretical work has shown possible membrane structures, azotosomes, in Titan liquids, azotosomes, composed of small organic nitrogen compounds, such as acrylonitrile. The search for a plausible information molecule for life in Titan liquids remains an open research topic-polyethers have been considered and shown to be insoluble at Titan temperatures. Possible search strategies for life on Titan include looking for unusual concentrations of certain molecules reflecting biological selection. Homochirality is a special and powerful example of such biology selection. Environmentally, a depletion of hydrogen in the lower atmosphere may be a sign of metabolism. A discovery of life in liquid methane and ethane would be our first compelling indication that the universe is full of diverse and wondrous life forms. PMID:26848689

  17. Titan as the Abode of Life.

    PubMed

    McKay, Christopher P

    2016-01-01

    Titan is the only world we know, other than Earth, that has a liquid on its surface. It also has a thick atmosphere composed of nitrogen and methane with a thick organic haze. There are lakes, rain, and clouds of methane and ethane. Here, we address the question of carbon-based life living in Titan liquids. Photochemically produced organics, particularly acetylene, in Titan's atmosphere could be a source of biological energy when reacted with atmospheric hydrogen. Light levels on the surface of Titan are more than adequate for photosynthesis, but the biochemical limitations due to the few elements available in the environment may lead only to simple ecosystems that only consume atmospheric nutrients. Life on Titan may make use of the trace metals and other inorganic elements produced by meteorites as they ablate in its atmosphere. It is conceivable that H₂O molecules on Titan could be used in a biochemistry that is rooted in hydrogen bonds in a way that metals are used in enzymes by life on Earth. Previous theoretical work has shown possible membrane structures, azotosomes, in Titan liquids, azotosomes, composed of small organic nitrogen compounds, such as acrylonitrile. The search for a plausible information molecule for life in Titan liquids remains an open research topic-polyethers have been considered and shown to be insoluble at Titan temperatures. Possible search strategies for life on Titan include looking for unusual concentrations of certain molecules reflecting biological selection. Homochirality is a special and powerful example of such biology selection. Environmentally, a depletion of hydrogen in the lower atmosphere may be a sign of metabolism. A discovery of life in liquid methane and ethane would be our first compelling indication that the universe is full of diverse and wondrous life forms.

  18. Titan as the Abode of Life

    NASA Technical Reports Server (NTRS)

    Mckay, Christopher P.

    2016-01-01

    Titan is the only world we know other than Earth that has a liquid on its surface. It has a thick atmosphere composed of nitrogen and methane with a thick organic haze. There are lakes, rain, and clouds of methane and ethane. Here, we address the question of carbon-based life living in Titan liquids. Photochemically produced organics, particularly acetylene, in Titan's atmosphere could be a source of biological energy when reacted with atmospheric hydrogen. Light levels on the surface of Titan are more than adequate for photosynthesis but the biochemical limitations due to the few elements available in the environment may lead only to simple ecosystems that only consume atmospheric nutrients. Life on Titan may make use of the trace metals and other inorganic elements produced by meteorites as they ablate in the atmosphere. It is conceivable that H2O molecules on Titan could be used in a biochemistry that is rooted in hydrogen bonds in a way that metals are used in enzymes by life on Earth. Previous theoretical work has shown possible membrane structures in Titan liquids, azotosomes, composed of small organic nitrogen compounds, such as acrylonitrile. The search for a plausible information molecule for life in Titan liquids remains an open research topic - polyethers have been considered and shown to be insoluble at Titan temperatures. Possible search strategies for life on Titan include looking for unusual concentrations of certain molecules reflecting biological selection. Homochirality is a special and powerful example of such biology selection. Environmentally, a depletion of hydrogen in the lower atmosphere may be a sign of metabolism. A discovery of life in liquid methane and ethane would be our first compelling indication that the Universe is full of diverse and wondrous life forms.

  19. Enhanced durability of high-temperature desulfurization sorbents for moving-bed applications. Option 2 Program: Development and testing of zinc titanate sorbents

    SciTech Connect

    Ayala, R.E.

    1993-04-01

    One of the most advantageous configurations of the integrated gasification combined cycle (IGCC) power system is coupling it with a hot gas cleanup for the more efficient production of electric power in an environmentally acceptable manner. In conventional gasification cleanup systems, closely heat exchangers are necessary to cool down the fuel gases for cleaning, sometimes as low as 200--300{degree}F, and to reheat the gases prior to injection into the turbine. The result is significant losses in efficiency for the overall power cycle. High-temperature coal gas cleanup in the IGCC system can be operated near 1000{degree}F or higher, i.e., at conditions compatible with the gasifier and turbine components, resulting is a more efficient overall system. GE is developing a moving-bed, high-temperature desulfurization system for IGCC power systems in which mixed-metal oxides are currently being used as desulfurization sorbents. The objective of this contract is to identify and test fabrication methods and sorbent chemical compositions that enhance the long-term chemical reactivity and mechanical durability of zinc ferrite and other novel sorbents for moving-bed, high-temperature desulfurization of coal-derived gases. Zinc ferrite was studied under the base program of this contract. In the next phase of this program novel sorbents, particularly zinc titanate-based sorbents, are being studied under the remaining optional programs. This topical report summarizes only the work performed under the Option 2 program. In the course of carrying out the program, more than 25 zinc titanate formulations have been prepared and characterized to identify formulations exhibiting enhanced properties over the baseline zinc titanate formulation selected by the US Department of Energy.

  20. Titan as the Abode of Life

    PubMed Central

    McKay, Christopher P.

    2016-01-01

    Titan is the only world we know, other than Earth, that has a liquid on its surface. It also has a thick atmosphere composed of nitrogen and methane with a thick organic haze. There are lakes, rain, and clouds of methane and ethane. Here, we address the question of carbon-based life living in Titan liquids. Photochemically produced organics, particularly acetylene, in Titan’s atmosphere could be a source of biological energy when reacted with atmospheric hydrogen. Light levels on the surface of Titan are more than adequate for photosynthesis, but the biochemical limitations due to the few elements available in the environment may lead only to simple ecosystems that only consume atmospheric nutrients. Life on Titan may make use of the trace metals and other inorganic elements produced by meteorites as they ablate in its atmosphere. It is conceivable that H2O molecules on Titan could be used in a biochemistry that is rooted in hydrogen bonds in a way that metals are used in enzymes by life on Earth. Previous theoretical work has shown possible membrane structures, azotosomes, in Titan liquids, azotosomes, composed of small organic nitrogen compounds, such as acrylonitrile. The search for a plausible information molecule for life in Titan liquids remains an open research topic—polyethers have been considered and shown to be insoluble at Titan temperatures. Possible search strategies for life on Titan include looking for unusual concentrations of certain molecules reflecting biological selection. Homochirality is a special and powerful example of such biology selection. Environmentally, a depletion of hydrogen in the lower atmosphere may be a sign of metabolism. A discovery of life in liquid methane and ethane would be our first compelling indication that the universe is full of diverse and wondrous life forms. PMID:26848689

  1. Effect of Non-Equilibrium Surface Thermochemistry in Simulation of Carbon Based Ablators

    NASA Technical Reports Server (NTRS)

    Chen, Yih-Kanq; Gokcen, Tahir

    2012-01-01

    This study demonstrates that coupling of a material thermal response code and a flow solver using non-equilibrium gas/surface interaction model provides time-accurate solutions for the multidimensional ablation of carbon based charring ablators. The material thermal response code used in this study is the Two-dimensional Implicit Thermal-response and AblatioN Program (TITAN), which predicts charring material thermal response and shape change on hypersonic space vehicles. Its governing equations include total energy balance, pyrolysis gas mass conservation, and a three-component decomposition model. The flow code solves the reacting Navier-Stokes equations using Data Parallel Line Relaxation (DPLR) method. Loose coupling between the material response and flow codes is performed by solving the surface mass balance in DPLR and the surface energy balance in TITAN. Thus, the material surface recession is predicted by finite-rate gas/surface interaction boundary conditions implemented in DPLR, and the surface temperature and pyrolysis gas injection rate are computed in TITAN. Two sets of nonequilibrium gas/surface interaction chemistry between air and the carbon surface developed by Park and Zhluktov, respectively, are studied. Coupled fluid-material response analyses of stagnation tests conducted in NASA Ames Research Center arc-jet facilities are considered. The ablating material used in these arc-jet tests was Phenolic Impregnated Carbon Ablator (PICA). Computational predictions of in-depth material thermal response and surface recession are compared with the experimental measurements for stagnation cold wall heat flux ranging from 107 to 1100 Watts per square centimeter.

  2. Titan Meteorology

    NASA Astrophysics Data System (ADS)

    Mitchell, Jonathan

    2012-04-01

    Titan’s methane clouds have received much attention since they were first discovered spectroscopically (Griffith et al. 1998). Titan's seasons evolve slowly, and there is growing evidence of a seasonal response in the regions of methane cloud formation (e.g. Rodriguez et al. 2009). A complete, three-dimensional view of Titan’s clouds is possible through the determination of cloud-top heights from Cassini images (e.g., Ádámkovics et al. 2010). Even though Titan’s surface is warmed by very little sunlight, we now know Titan’s methane clouds are convective, evolving through tens of kilometers of altitude on timescales of hours to days with dynamics similar to clouds that appear on Earth (Porco et al. 2005). Cassini ISS has also shown evidence of rain storms on Titan that produce surface accumulation of methane (Turtle et al. 2009). Most recently, Cassini has revealed a 1000-km-scale, arrow-shaped cloud at the equator followed by changes that appear to be evidence of surface precipitation (Turtle et al. 2011b). Individual convective towers simulated with high fidelity indicate that surface convergence of methane humidity and dynamic lifting are required to trigger deep, precipitating convection (e.g. Barth & Rafkin 2010). The global expanses of these cloud outbursts, the evidence for surface precipitation, and the requirement of dynamic convergence and lifting at the surface to trigger deep convection motivate an analysis of storm formation in the context of Titan’s global circulation. I will review our current understanding of Titan’s methane meteorology using Cassini and ground-based observations and, in particular, global circulation model simulations of Titan’s methane cycle. When compared with cloud observations, our simulations indicate an essential role for planetary-scale atmospheric waves in organizing convective storms on large scales (Mitchell et al. 2011). I will end with predictions of Titan’s weather during the upcoming northern

  3. Titanic: A Statistical Exploration.

    ERIC Educational Resources Information Center

    Takis, Sandra L.

    1999-01-01

    Uses the available data about the Titanic's passengers to interest students in exploring categorical data and the chi-square distribution. Describes activities incorporated into a statistics class and gives additional resources for collecting information about the Titanic. (ASK)

  4. Titan Haze

    NASA Technical Reports Server (NTRS)

    Anderson, Carrie M.; West, Robert; Lavvas, Panayotis

    2011-01-01

    The Titan haze exerts a dominating influence on surface visibility and atmospheric radiative heating at optical and near-infrared wavelengths and our desire to understand surface composition and atmospheric dynamics provides a strong motivation to study the properties of the haze. Prior to the Cassini/Huygens missions the haze was known to be global in extent, with a hemispheric contrast asymmetry, with a complicated structure in the polar vortex region poleward of about 55 deg latitude, and with a distinct layer near 370 km altitude outside of the polar vortex at the time of the Voyager 2 flyby. The haze particles measured by the Pioneer and Voyager spacecraft were both highly polarizing and strongly forward scattering, a combination that seems to require an aggregation of small (several tens of nm radius) primary particles. These same properties were seen in the Cassini orbiter and Huygens Probe data. The most extensive set of optical measurements were made inside the atmosphere by the Descent Imager/Spectral Radiometer (DISR) instrument on the Huygens Probe. At the probe location as determined by the DISR measurements the average haze particle contained about 3000 primary particles whose radius is about 40 nm. Three distinct vertical regions were seen in the DISR data with differing particle properties. Refractive indices of the particles in the main haze layer resemble those reported by Khare et al. between O.3S and about 0.7 micron but are more absorbing than the Khare et al. results between 0.7 micron and the long-wavelength limit of the DISR spectra at 1.6 micron. These and other results are described by Tomasko et al., and a broader summary of results was given by Tomasko and West,. New data continue to stream in from the Cassini spacecraft. New data analyses and new laboratory and model results continue to move the field forward. Titan's 'detached' haze layer suffered a dramatic drop in altitude near equinox in 2009 with implications for the circulation

  5. The Climate of Titan

    NASA Astrophysics Data System (ADS)

    Mitchell, Jonathan L.; Lora, Juan M.

    2016-06-01

    Over the past decade, the Cassini-Huygens mission to the Saturn system has revolutionized our understanding of Titan and its climate. Veiled in a thick organic haze, Titan's visible appearance belies an active, seasonal weather cycle operating in the lower atmosphere. Here we review the climate of Titan, as gleaned from observations and models. Titan's cold surface temperatures (˜90 K) allow methane to form clouds and precipitation analogously to Earth's hydrologic cycle. Because of Titan's slow rotation and small size, its atmospheric circulation falls into a regime resembling Earth's tropics, with weak horizontal temperature gradients. A general overview of how Titan's atmosphere responds to seasonal forcing is provided by estimating a number of climate-related timescales. Titan lacks a global ocean, but methane is cold-trapped at the poles in large seas, and models indicate that weak baroclinic storms form at the boundary of Titan's wet and dry regions. Titan's saturated troposphere is a substantial reservoir of methane, supplied by deep convection from the summer poles. A significant seasonal cycle, first revealed by observations of clouds, causes Titan's convergence zone to migrate deep into the summer hemispheres, but its connection to polar convection remains undetermined. Models suggest that downwelling of air at the winter pole communicates upper-level radiative cooling, reducing the stability of the middle troposphere and priming the atmosphere for spring and summer storms when sunlight returns to Titan's lakes. Despite great gains in our understanding of Titan, many challenges remain. The greatest mystery is how Titan is able to retain an abundance of atmospheric methane with only limited surface liquids, while methane is being irreversibly destroyed by photochemistry. A related mystery is how Titan is able to hide all the ethane that is produced in this process. Future studies will need to consider the interactions between Titan's atmosphere, surface

  6. Does Titan have oceans?

    NASA Astrophysics Data System (ADS)

    Lunine, J. I.

    1994-04-01

    Titan is one of the few worlds in the solar system whose essential nature remains hidden. Satellite data from Voyager are examined. Remote sensing investigations from Earth are explored. Possible models of Titan's surface are reviewed. A closer look at Titan would provide useful information. The data to be gathered by the planetary mission Cassini is discussed.

  7. Intensive Titan exploration begins

    NASA Technical Reports Server (NTRS)

    Mahaffy, Paul R.

    2005-01-01

    The Cassini Orbiter spacecraft first skimmed through the tenuous upper atmosphere of Titan on 26 October 2004. This moon of Saturn is unique in our solar system, with a dense nitrogen atmosphere that is cold enough in places to rain methane, the feedstock for the atmospheric chemistry that produces hydrocarbons, nitrile compounds, and Titan's orange haze. The data returned from this flyby supply new information on the magnetic field and plasma environment around Titan, expose new facets of the dynamics and chemistry of Titan's atmosphere, and provide the first glimpses of what appears to be a complex, fluid-processed, geologically young Titan surface.

  8. Intensive Titan exploration begins.

    PubMed

    Mahaffy, Paul R

    2005-05-13

    The Cassini Orbiter spacecraft first skimmed through the tenuous upper atmosphere of Titan on 26 October 2004. This moon of Saturn is unique in our solar system, with a dense nitrogen atmosphere that is cold enough in places to rain methane, the feedstock for the atmospheric chemistry that produces hydrocarbons, nitrile compounds, and Titan's orange haze. The data returned from this flyby supply new information on the magnetic field and plasma environment around Titan, expose new facets of the dynamics and chemistry of Titan's atmosphere, and provide the first glimpses of what appears to be a complex, fluid-processed, geologically young Titan surface.

  9. CHARACTERIZATION REPORT FOR STRONTIUM TITANATE IN SWSA 7 AND ADJACENT PARCELS IN SUPPORT OF THE NATIONAL PRIORITIES LIST SITE BOUNDARY DEFINITION PROGRAM OAK RIDGE, TENNESSEE

    SciTech Connect

    David A. King

    2011-10-10

    The U.S. Department of Energy (DOE) Oak Ridge Office requested support from the Oak Ridge Institute for Science and Education (ORISE) contract to delineate the extent of strontium titanate (SrTiO3) contamination in and around Solid Waste Storage Area (SWSA) 7 as part of the Oak Ridge National Priorities List Site boundary definition program. The study area is presented in Fig. 1.1 relative to the Oak Ridge Reservation (ORR). The investigation was executed according to Sampling and Analysis Plan/Quality Assurance Project Plan (SAP/QAPP) (DOE 2011) to supplement previous investigations noted below and to determine what areas, if any, have been adversely impacted by site operations.

  10. Touchdown on Titan

    NASA Technical Reports Server (NTRS)

    Morring, Frank, Jr.

    2004-01-01

    Europe's Huygens probe is on target for a Dec. 25 separation from the Cassini Saturn orbiter that has carried it like a baby for more than seven years. The probe will spend three weeks coasting to a plunge into Titan's thick atmosphere on the morning of Jan. 14. If all goes as planned, the 349-kg. Huygens will spend more than 2 hr. descending by parachute to the mysterious surface of the planet-sized moon, and hopefully devote yet more time to broadcasting data after it lands. Before the day is over, Huygens is programmed to beam about 30 megabytes of data - including some 1,100 images-back to Earth through Cassini, a trip that will take some 75 min. to complete over the 1- billion-km. distance that separates the two planets. Within that data should be answers to questions that date back to 1655, when Dutch astronomer Christiaan Huygens found the moon with a homemade telescope and named it for the family of giants the ancient Greeks believed once ruled the earth. In the Solar System, there is no other world like Titan, with a nitrogen and methane atmospheric and a cold, hidden surface darker than Earth under the full Moon.

  11. Accelerated Application Development: The ORNL Titan Experience

    SciTech Connect

    Joubert, Wayne; Archibald, Richard K.; Berrill, Mark A.; Brown, W. Michael; Eisenbach, Markus; Grout, Ray; Larkin, Jeff; Levesque, John; Messer, Bronson; Norman, Matthew R.; Philip, Bobby; Sankaran, Ramanan; Tharrington, Arnold N.; Turner, John A.

    2015-05-09

    The use of computational accelerators such as NVIDIA GPUs and Intel Xeon Phi processors is now widespread in the high performance computing community, with many applications delivering impressive performance gains. However, programming these systems for high performance, performance portability and software maintainability has been a challenge. In this paper we discuss experiences porting applications to the Titan system. Titan, which began planning in 2009 and was deployed for general use in 2013, was the first multi-petaflop system based on accelerator hardware. To ready applications for accelerated computing, a preparedness effort was undertaken prior to delivery of Titan. In this paper we report experiences and lessons learned from this process and describe how users are currently making use of computational accelerators on Titan.

  12. Accelerated Application Development: The ORNL Titan Experience

    DOE PAGES

    Joubert, Wayne; Archibald, Richard K.; Berrill, Mark A.; Brown, W. Michael; Eisenbach, Markus; Grout, Ray; Larkin, Jeff; Levesque, John; Messer, Bronson; Norman, Matthew R.; et al

    2015-05-09

    The use of computational accelerators such as NVIDIA GPUs and Intel Xeon Phi processors is now widespread in the high performance computing community, with many applications delivering impressive performance gains. However, programming these systems for high performance, performance portability and software maintainability has been a challenge. In this paper we discuss experiences porting applications to the Titan system. Titan, which began planning in 2009 and was deployed for general use in 2013, was the first multi-petaflop system based on accelerator hardware. To ready applications for accelerated computing, a preparedness effort was undertaken prior to delivery of Titan. In this papermore » we report experiences and lessons learned from this process and describe how users are currently making use of computational accelerators on Titan.« less

  13. Hubble Observes Surface of Titan

    NASA Technical Reports Server (NTRS)

    1994-01-01

    thicker.

    Smith's group used the Hubble Space Telescope's WideField/Planetary Camera 2 at near-infrared wavelengths (between .85 and 1.05 microns). Titan's haze is transparent enough in this wavelength range to allow mapping of surface features according to their reflectivity. Only Titan's polar regions could not be mapped this way, due to the telescope's viewing angle of the poles and the thick haze near the edge of the disk. Their image-resolution (that is, the smallest distance seen in detail) with the WFPC2 at the near-infrared wavelength is 360 miles. The 14 images processed and compiled into the Titan surface map were as 'noise' free, or as free of signal interference, as the space telescope allows, Smith said.

    Titan makes one complete orbit around Saturn in 16 days, roughly the duration of the imaging project. Scientists have suspected that Titan's rotation also takes 16 days, so that the same hemisphere of Titan always faces Saturn, just as the same hemisphere of the Earth's moon always faces the Earth. Recent observations by Lemmon and colleagues at the University of Arizona confirm this true.

    It's too soon to conclude much about what the dark and bright areas in the Hubble Space Telescope images are -- continents, oceans, impact craters or other features, Smith said. Scientists have long suspected that Titan's surface was covered with a global ehtane-methane ocean. The new images show that there is at least some solid surface.

    Smith's team made a total 50 images of Titan last month in their program, a project to search for small scale features in Titan's lower atmosphere and surface. They have yet to analyze images for information about Titan's clouds and winds. That analysis could help explain if the bright areas are major impact craters in the frozen water ice-and-rock or higher-altitude features.

    The images are important information for the Cassini mission, which is to launch a robotic spacecraft on a 7-year journey to Saturn in October 1997

  14. A users manual for a revised version of the Langley charring ablator program

    NASA Technical Reports Server (NTRS)

    Stroud, C. W.; Brinkley, K. L.

    1975-01-01

    A computer program is described that will compute the transient response of a thermal protection material to a prescribed heat input at the surface. The program has the capability of analyzing pyrolysis gas chemical kinetics in detail and treating pyrolysis reactions-in-depth. Deposition of solid products produced by chemical reactions in the gas phase is included in the analysis. An outline is given for the theory. detailed operating instructions for the computer program are included.

  15. Millimeter and Submillimeter Spectroscopy of Titan

    NASA Technical Reports Server (NTRS)

    Gurwell, Mark A.

    2003-01-01

    Our major goals for the first year of this program were to develop a general improved radiative transfer model of the atmosphere of Titan, and to accurately determine the global abundance of CO from observations obtained using the Owens Valley Radio Observatory Millimeter Array. Other goals were to reanalyze older data sets using the improved radiative transfer model and to observe other molecular species as time permitted. Our program was granted two Titan transits to measure the CO(2-1) rotational transition at low spatial resolution, and one transit to measure nitriles and organics in the 236-239 GHz spectral range. In year two, our program was granted two Titan transits to measure the CO(2-1) rotational transition at low spatial resolution, and one transit to measure nitriles and organics in the 236-239 GHz spectral range. The CO(2-1) observations were previously reported in a published paper

  16. Cassini/CIRS Observations of Water Vapor in Titan's Stratosphere

    NASA Astrophysics Data System (ADS)

    Bjoraker, Gordon; Achterberg, R.; Anderson, C.; Samuelson, R.; Carlson, R.; Jennings, D.

    2008-09-01

    The Composite Infrared Spectrometer (CIRS) on the Cassini spacecraft has obtained spectra of Titan during most of the 44 flybys of the Cassini prime mission. Water vapor on Titan was first detected using whole-disk observations from the Infrared Space Observatory (Coustenis et al 1998, Astron. Astrophys. 336, L85-L89). CIRS data permit the retrieval of the latitudinal variation of water on Titan and some limited information on its vertical profile. Emission lines of H2O on Titan are very weak in the CIRS data. Thus, large spectral averages as well as improvements in calibration are necessary to detect water vapor. Water abundances were retrieved in nadir spectra at 55 South, the Equator, and at 19 North. Limb spectra of the Equator were also modeled to constrain the vertical distribution of water. Stratospheric temperatures in the 0.5 - 4.0 mbar range were obtained by inverting spectra of CH4 in the ν4 band centered at 1304 cm-1. The temperature in the lower stratosphere (4 - 20 mbar) was derived from fitting pure rotation lines of CH4 between 80 and 160 cm-1. The origin of H2O and CO2 is believed to be from the ablation of micrometeorites containing water ice, followed by photochemistry. This external source of water originates either within the Saturn system or from the interplanetary medium. Recently, Horst et al (J. Geophys. Res. 2008, in press) developed a photochemical model of Titan in which there are two external sources of oxygen. Oxygen ions (probably from Enceladus) precipitate into Titan's atmosphere to form CO at very high altitudes (1100 km). Water ice ablation at lower altitudes (700 km) forms H2O and subsequent chemistry produces CO2. CIRS measurements of CO, CO2, and now of H2O will provide valuable constraints to these photochemical models and improve our understanding of oxygen chemistry on Titan.

  17. Cassini/CIRS Observations of Water Vapor in Titan's Stratosphere

    NASA Technical Reports Server (NTRS)

    Bjoraker, Gordon L.; Achterberg, R. K.; Anderson, C. M.; Samuelson, R. E.; Carlson, R. C.; Jennings, D. E.

    2008-01-01

    The Composite Infrared Spectrometer (CIRS) on the Cassini spacecraft has obtained spectra of Titan during most of the 44 flybys of the Cassini prime mission. Water vapor on Titan was first detected using whole-disk observations from the Infrared Space Observatory (Coustenis et al 1998, Astron. Astrophys. 336, L85-L89). CIRS data permlt the retrieval of the latitudinal variation of water on Titan and some limited information on its vertical profile. Emission lines of H2O on Titan are very weak in the CIRS data. Thus, large spectral averages as well as improvements in calibration are necessary to detect water vapor. Water abundances were retrieved in nadir spectra at 55 South, the Equator, and at 19 North. Limb spectra of the Equator were also modeled to constrain the vertical distribution of water. Stratospheric temperatures in the 0.5 - 4.0 mbar range were obtained by inverting spectra of CH4 in the v4 band centered at 1304/cm. The temperature in the lower stratosphere (4 - 20 mbar) was derived from fitting pure rotation lines of CH4 between 80 and 160/cm. The origin of H2O and CO2 is believed to be from the ablation of micrometeorites containing water ice, followed by photochemistry. This external source of water originates either within the Saturn system or from the interplanetary medium. Recently, Horst et al (J. Geophys. Res. 2008, in press) developed a photochemical model of Titan in which there are two external sources of oxygen. Oxygen ions (probably from Enceladus) precipitate into Titan's atmosphere to form CO at very high altitudes (1100 km). Water ice ablation at lower altitudes (700 km) forms H2O and subsequent chemistry produces CO2. CIRS measurements of CO, CO2, and now of H2O will provide valuable constraints to these photochemical models and - improve our understanding of oxygen chemistry on Titan.

  18. Titan's Exotic Weather

    NASA Astrophysics Data System (ADS)

    Griffith, Caitlin A.

    2006-09-01

    Images of Titan, taken during the joint NASA and European Space Agency Cassini-Huygens mission, invoke a feeling of familiarity: washes wind downhill to damp lakebeds; massive cumuli form and quickly dissipate, suggestive of rain; and dark oval regions resemble lakes. These features arise from Titan's unique similarity with Earth: both cycle liquid between their surfaces and atmospheres, but in Titan's cool atmosphere it is methane that exists as a gas, liquid, and ice. While Titan enticingly resembles Earth, its atmosphere is 10 times thicker, so that its radiative time constant near the surface exceeds a Titan year, and prohibits large thermal gradients and seasonal surface temperature variations exceeding 3K. Titan also lacks oceans - central to Earth's climate - and instead stores much of its condensible in its atmosphere. As a result, Titan's weather differs remarkably from Earth's. Evidence for this difference appears in the location of Titan's large clouds, which frequent a narrow band at 40S latitude and a region within 30 latitude of the S. Pole. Ground-based and Cassini observations, combined with thermodynamic considerations, indicate that we are seeing large convective cloud systems. Detailed cloud models and general circulation models further suggest that these are severe rain storms, which will migrate with the change in season. Outside these migrating "gypsy" cloud bands, the atmosphere appears to be calm, humid and thus frequented by thin stratiform clouds. An intriguingly alien environment is predicted. Yet, the combined effects of Titan's patchy wet surface, atmospheric tides, possible ice volcanoes, and detailed seasonal variations remain unclear as we have witnessed only one season so far. This talk will review observations of Titan's lower atmosphere and modeling efforts to explain the observations, and explore the questions that still elude us.

  19. Hubble Observes Surface of Titan

    NASA Technical Reports Server (NTRS)

    1994-01-01

    thicker.

    Smith's group used the Hubble Space Telescope's WideField/Planetary Camera 2 at near-infrared wavelengths (between .85 and 1.05 microns). Titan's haze is transparent enough in this wavelength range to allow mapping of surface features according to their reflectivity. Only Titan's polar regions could not be mapped this way, due to the telescope's viewing angle of the poles and the thick haze near the edge of the disk. Their image-resolution (that is, the smallest distance seen in detail) with the WFPC2 at the near-infrared wavelength is 360 miles. The 14 images processed and compiled into the Titan surface map were as 'noise' free, or as free of signal interference, as the space telescope allows, Smith said.

    Titan makes one complete orbit around Saturn in 16 days, roughly the duration of the imaging project. Scientists have suspected that Titan's rotation also takes 16 days, so that the same hemisphere of Titan always faces Saturn, just as the same hemisphere of the Earth's moon always faces the Earth. Recent observations by Lemmon and colleagues at the University of Arizona confirm this true.

    It's too soon to conclude much about what the dark and bright areas in the Hubble Space Telescope images are -- continents, oceans, impact craters or other features, Smith said. Scientists have long suspected that Titan's surface was covered with a global ehtane-methane ocean. The new images show that there is at least some solid surface.

    Smith's team made a total 50 images of Titan last month in their program, a project to search for small scale features in Titan's lower atmosphere and surface. They have yet to analyze images for information about Titan's clouds and winds. That analysis could help explain if the bright areas are major impact craters in the frozen water ice-and-rock or higher-altitude features.

    The images are important information for the Cassini mission, which is to launch a robotic spacecraft on a 7-year journey to Saturn in October 1997

  20. i-motif-driven Au nanomachines in programmed siRNA delivery for gene-silencing and photothermal ablation.

    PubMed

    Son, Sejin; Nam, Jutaek; Kim, Jinhwan; Kim, Sungjee; Kim, Won Jong

    2014-06-24

    The present work illustrates unique design, construction and operation of an i-motif-based DNA nanomachine templated on gold nanoparticles (AuNPs), which utilizes pH-responsive dynamic motion of i-motif DNA strands and aggregational behavior of AuNPs to elicit programmed delivery of therapeutic siRNA. The pH-sensitive nucleic acids immobilized on the AuNPs consisted of three functional segments, i.e., an i-motif DNA, an overhanging linker DNA and a therapeutic siRNA. At neutral pH, the i-motif DNA is hybridized with the overhanging linker DNA segment of the therapeutic siRNA. However, in endosomal acidic pH, the i-motif DNA forms interstrand tetraplex, which could induce cluster formation of AuNPs resulting in endosomal escape of AuNP clusters, and produce a high gene silencing efficiency by releasing siRNA in the cytosol. Furthermore, the cluster formation of AuNPs accelerated photothermal ablation of cells when irradiated with laser. Precise and synchronized biomechanical motion in subcellular microenvironment is realized through judicious integration of pH-responsive behavior of the i-motif DNA and AuNPs, and meticulous designing of DNA.

  1. Oxygen Chemistry in Titan's Atmosphere

    NASA Astrophysics Data System (ADS)

    Wilson, E. H.; Atreya, S. K.

    2002-09-01

    Oxygen chemistry in the atmosphere of Titan is controlled by the presence of CO and a likely influx of extraplanetary oxygen. The presence of water vapor, corroborated by the Infrared Space Observatory (ISO) stratospheric detection [1], combined with CO induces the formation of CO2, which has also been observed [2]. However, the high CO/H2O ratio in Titan's atmosphere causes the propagation of oxygen chemistry to follow a different path than what is predicted for the Jovian planets. Specifically, the efficient CO recycling mechanisms serve to inhibit significant formation of larger oxygen compounds such as CH3OH (methanol) and CH2CO (ketene). The results of a 1-D photochemical model are presented in the context of identifying possible oxygen compounds that might be detected by the Cassini/Huygens mission which will arrive at Titan in 2004. This work was supported by the NASA Planetary Atmospheres Program and by the GCMS Project of the Cassini/Huygens mission. [1] A. Coustenis et al., Astron. Astrophys., 336, L85-L89, 1998. [2] A. Coustenis et al., Icarus, 80, 54-76, 1989.

  2. The evolution of the Titan rocket - Titan I to Titan II

    NASA Astrophysics Data System (ADS)

    Adams, Laurence J.

    1990-10-01

    The Titan I and Titan II rockets are described. The designs of the stages, test stands, and basing systems are considered, and the developmental history of each rocket is briefly recapitulated. The ways in which Titan II represents an evolution from Titan I are pointed out.

  3. Titan's organic chemistry

    NASA Technical Reports Server (NTRS)

    Sagan, C.; Thompson, W. R.; Khare, B. N.

    1985-01-01

    Voyager discovered nine simple organic molecules in the atmosphere of Titan. Complex organic solids, called tholins, produced by irradiation of the simulated Titanian atmosphere, are consistent with measured properties of Titan from ultraviolet to microwave frequencies and are the likely main constituents of the observed red aerosols. The tholins contain many of the organic building blocks central to life on earth. At least 100-m, and possibly kms thicknesses of complex organics have been produced on Titan during the age of the solar system, and may exist today as submarine deposits beneath an extensive ocean of simple hydrocarbons.

  4. Raising the Titanic.

    ERIC Educational Resources Information Center

    Baker, Romona

    1990-01-01

    Described is an activity in which groups of students investigate engineering principles by writing a feasibility study to raise the luxury liner, Titanic. The problem statement and directions, and suggestions for problem solutions are included. (CW)

  5. The greenhouse of Titan.

    NASA Technical Reports Server (NTRS)

    Sagan, C.

    1973-01-01

    Analysis of non-gray radiative equilibrium and gray convective equilibrium on Titan suggests that a massive molecular-hydrogen greenhouse effect may be responsible for the disagreement between the observed IR temperatures and the equilibrium temperature of an atmosphereless Titan. Calculations of convection indicate a probable minimum optical depth of 14 which corresponds to a molecular hydrogen shell of substantial thickness with total pressures of about 0.1 bar. It is suggested that there is an equilibrium between outgassing and blow-off on the one hand and accretion from the protons trapped in a hypothetical Saturnian magnetic field on the other, in the present atmosphere of Titan. It is believed that an outgassing equivalent to the volatilization of a few kilometers of subsurface ice is required to maintain the present blow-off rate without compensation for all geological time. The presence of an extensive hydrogen corona around Titan is postulated, with surface temperatures up to 200 K.

  6. First Titan-Centaur Launch Test

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The first Titan/Centaur lifted off from Complex 41 at Cape Kennedy Air Force Station at 9:48 AM EDT. The Titan stages burned as programmed, but when the Centaur stage failed to ignite, the Range Safety Officer destroyed it. The new NASA rocket was launched on a proof of concept flight designed to prepare it for twin Viking launches to Mars in 1975 and other missions involving heavy payloads. The 160-foot-tall rocket combines the Air Force Titan III with the NASA high-energy Centaur final stage. The twin solid rocket boosters have a combined liftoff thrust of 2.4 million pounds. Aboard Titan/ Centaur on its proof of concept flight were a dynamic simulator of the Viking spacecraft and a small scientific satellite (SPHINX) designed to determine how high voltage solar cells, insulators, and conductors are affected by the charges particles in space. KSC's Unmanned Launch Operations Directorate conducted the launch. For more information about Titan and Centaur, please see Chapters 4 and 8, respectively, in Roger Launius and Dennis Jenkins' book To Reach the High Frontier published by The University Press of Kentucky in 2002.

  7. Titan - Some new results

    SciTech Connect

    Owen, T.; Gautier, D.

    1989-01-01

    New analyses of Voyager spectra of Titan have led to improvements in the determination of abundances of minor constituents as a function of latitude and altitude. Ground-based microwave observations have extended the Voyager results for HCN, and have demonstrated that CO is mysteriously deficient in the stratosphere. The origin of the CH4, CO, and N2 in Titan's atmosphere is still unresolved. Both primordial and evolutionary sources are compatible with the available evidence. 21 refs.

  8. Clash of the Titans

    ERIC Educational Resources Information Center

    Subramaniam, Karthigeyan

    2010-01-01

    WebQuests and the 5E learning cycle are titans of the science classroom. These popular inquiry-based strategies are most often used as separate entities, but the author has discovered that using a combined WebQuest and 5E learning cycle format taps into the inherent power and potential of both strategies. In the lesson, "Clash of the Titans,"…

  9. Titan's Ammonia Feature

    NASA Technical Reports Server (NTRS)

    Smythe, W.; Nelson, R.; Boryta, M.; Choukroun, M.

    2011-01-01

    NH3 has long been considered an important component in the formation and evolution of the outer planet satellites. NH3 is particularly important for Titan, since it may serve as the reservoir for atmospheric nitrogen. A brightening seen on Titan starting in 2004 may arise from a transient low-lying fog or surface coating of ammonia. The spectral shape suggests the ammonia is anhydrous, a molecule that hydrates quickly in the presence of water.

  10. Is Titan Partially Differentiated?

    NASA Astrophysics Data System (ADS)

    Mitri, G.; Pappalardo, R. T.; Stevenson, D. J.

    2009-12-01

    The recent measurement of the gravity coefficients from the Radio Doppler data of the Cassini spacecraft has improved our knowledge of the interior structure of Titan (Rappaport et al. 2008 AGU, P21A-1343). The measured gravity field of Titan is dominated by near hydrostatic quadrupole components. We have used the measured gravitational coefficients, thermal models and the hydrostatic equilibrium theory to derive Titan's interior structure. The axial moment of inertia gives us an indication of the degree of the interior differentiation. The inferred axial moment of inertia, calculated using the quadrupole gravitational coefficients and the Radau-Darwin approximation, indicates that Titan is partially differentiated. If Titan is partially differentiated then the interior must avoid melting of the ice during its evolution. This suggests a relatively late formation of Titan to avoid the presence of short-lived radioisotopes (Al-26). This also suggests the onset of convection after accretion to efficiently remove the heat from the interior. The outer layer is likely composed mainly of water in solid phase. Thermal modeling indicates that water could be present also in liquid phase forming a subsurface ocean between an outer ice I shell and a high pressure ice layer. Acknowledgments: This work was conducted at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

  11. Enhanced airglow at Titan

    NASA Astrophysics Data System (ADS)

    Royer, Emilie; Esposito, Larry; Wahlund, Jan-Erik

    2016-06-01

    The Cassini Ultraviolet Imaging Spectrograph (UVIS) instrument made thousand of observations of Titan since its arrival in the Saturnian system in 2004, but only few of them have been analyzed yet. Using the imaging capability of UVIS combined to a big data analytics approach, we have been able to uncover an unexpected pattern in this observations: on several occasions the Titan airglow exhibits an enhanced brightness by approximately a factor of 2, generally combined with a lower altitude of the airglow emission peak. These events typically last from 10 to 30 minutes and are followed and preceded by an airglow of regular and expected level of brightness and altitude. Observations made by the Cassini Plasma Spectrometer (CAPS) instrument onboard Cassini allowed us to correlate the enhanced airglow observed on T-32 with an electron burst. The timing of the burst and the level of energetic electrons (1 keV) observed by CAPS correspond to a brighter and lower than typical airglow displayed on the UVIS data. Furthermore, during T-32 Titan was inside the Saturn's magnetosheath and thus more subject to bombardment by energetic particles. However, our analysis demonstrates that the presence of Titan inside the magnetosheath is not a necessary condition for the production of an enhanced airglow, as we detected other similar events while Titan was within Saturn's magnetosphere. The study presented here aims to a better understanding of the interactions of Titan's upper atmosphere with its direct environment.

  12. Titan's surface and atmosphere

    NASA Astrophysics Data System (ADS)

    Hayes, Alexander G.; Soderblom, Jason M.; Ádámkovics, Máté

    2016-05-01

    Since its arrival in late 2004, the NASA/ESA Cassini-Huygens mission to Saturn has revealed Titan to be a world that is both strange and familiar. Titan is the only extraterrestrial body known to support standing bodies of stable liquid on its surface and, along with Earth and early Mars, is one of three places in the Solar System known to have had an active hydrologic cycle. With atmospheric pressures of 1.5 bar and temperatures of 90-95 K at the surface, methane and ethane condense out of Titan's nitrogen-dominated atmosphere and flow as liquids on the surface. Despite vast differences in environmental conditions and materials from Earth, Titan's methane-based hydrologic cycle drives climatic and geologic processes which generate landforms that are strikingly similar to their terrestrial counterparts, including vast equatorial dunes, well-organized channel networks that route material through erosional and depositional landscapes, and lakes and seas of liquid hydrocarbons. These similarities make Titan a natural laboratory for studying the processes that shape terrestrial landscapes and drive climates, probing extreme conditions impossible to recreate in earthbound laboratories. Titan's exotic environment ensures that even rudimentary measurements of atmospheric/surface interactions, such as wind-wave generation or aeolian dune development, provide valuable data to anchor physical models.

  13. The TITAN reversed-field-pinch fusion reactor study

    SciTech Connect

    Not Available

    1990-01-01

    This report discusses the following topics: overview of titan-2 design; titan-2 fusion-power-core engineering; titan-2 divertor engineering; titan-2 tritium systems; titan-2 safety design and radioactive-waste disposal; and titan-2 maintenance procedures.

  14. Witnessing Springtime on Titan

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-02-01

    Have you ever wondered what springtime is like on Saturns largest moon, Titan? A team of researchers has analyzed a decade of data from the Cassini spacecraft to determine how Titans gradual progression through seasons has affected its temperatures.Observing the Saturn SystemThough Titan orbits Saturn once every ~16 days, it is Saturns ~30-year march around the Sun that sets Titans seasons: each traditional season on Titan spans roughly 7.5 years. Thus, when the Cassini spacecraft first arrived at Saturn in 2004 to study the giant planet and its ring system and moons, Titans northern hemisphere was in early winter. A decade later, the season in the northern hemisphere had advanced to late spring.A team scientists led by Donald Jennings (Goddard Space Flight Center) has now used data from the Composite Infrared Spectrometer (CIRS) on board Cassini to analyze the evolution of Titans surface temperature between 2004 and 2014.Changing of SeasonsSurface brightness temperatures (with errors) on Titan are shown in blue for five time periods between 2004 and 2014. The location of maximum temperature migrates from 19S to 16N over the decade. Two climate models are also shown in green (high thermal inertia) and red (low thermal inertia). [Jennings et al. 2016]CIRS uses the decreased opacity of Titans atmosphere at 19 m to detect infrared emission from Titans surface at this wavelength. From this data, Jennings and collaborators determine Titans surface temperature for five time intervals between 2004 and 2014. They bin the data into 10 latitude bins that span from the south pole (90S) to the north pole (90N).The authors find that the maximum temperature on the moon stays stable over the ten-year period at 94 K, or a chilly -240F). But as time passes, the latitude with the warmest temperature shifts from 19S to 16N, marking the transition from early winter to late spring. Over the decade of monitoring, the surface temperature near the south pole decreased by ~2 K, and that

  15. Clash of the Titans: Booker T. Washington and W. E. B. Du Bois. Curriculum Based Education Program, Grade 11.

    ERIC Educational Resources Information Center

    National Park Service (Dept. of Interior), Washington, DC.

    The Booker T. Washington National Monument preserves and protects the birth site and childhood home of Booker T. Washington while interpreting his life experiences and significance in U.S. history as the most powerful African American between 1895 and 1915. The programs and activities included in this guide about the Booker T. Washington and W. E.…

  16. The environment of Titan, 1975

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Information regarding the physical characteristics of Titan and atmospheric models necessary to support design and mission planning of spacecraft that are to orbit Titan, enter its atmosphere or land on its surface is given.

  17. Titan Polar Landscape Evolution

    NASA Technical Reports Server (NTRS)

    Moore, Jeffrey M.

    2016-01-01

    With the ongoing Cassini-era observations and studies of Titan it is clear that the intensity and distribution of surface processes (particularly fluvial erosion by methane and Aeolian transport) has changed through time. Currently however, alternate hypotheses substantially differ among specific scenarios with respect to the effects of atmospheric evolution, seasonal changes, and endogenic processes. We have studied the evolution of Titan's polar region through a combination of analysis of imaging, elevation data, and geomorphic mapping, spatially explicit simulations of landform evolution, and quantitative comparison of the simulated landscapes with corresponding Titan morphology. We have quantitatively evaluated alternate scenarios for the landform evolution of Titan's polar terrain. The investigations have been guided by recent geomorphic mapping and topographic characterization of the polar regions that are used to frame hypotheses of process interactions, which have been evaluated using simulation modeling. Topographic information about Titan's polar region is be based on SAR-Topography and altimetry archived on PDS, SAR-based stereo radar-grammetry, radar-sounding lake depth measurements, and superposition relationships between geomorphologic map units, which we will use to create a generalized topographic map.

  18. Methane drizzle on Titan.

    PubMed

    Tokano, Tetsuya; McKay, Christopher P; Neubauer, Fritz M; Atreya, Sushil K; Ferri, Francesca; Fulchignoni, Marcello; Niemann, Hasso B

    2006-07-27

    Saturn's moon Titan shows landscapes with fluvial features suggestive of hydrology based on liquid methane. Recent efforts in understanding Titan's methane hydrological cycle have focused on occasional cloud outbursts near the south pole or cloud streaks at southern mid-latitudes and the mechanisms of their formation. It is not known, however, if the clouds produce rain or if there are also non-convective clouds, as predicted by several models. Here we show that the in situ data on the methane concentration and temperature profile in Titan's troposphere point to the presence of layered optically thin stratiform clouds. The data indicate an upper methane ice cloud and a lower, barely visible, liquid methane-nitrogen cloud, with a gap in between. The lower, liquid, cloud produces drizzle that reaches the surface. These non-convective methane clouds are quasi-permanent features supported by the global atmospheric circulation, indicating that methane precipitation occurs wherever there is slow upward motion. This drizzle is a persistent component of Titan's methane hydrological cycle and, by wetting the surface on a global scale, plays an active role in the surface geology of Titan.

  19. Titan Orbiter Aerorover Mission

    NASA Technical Reports Server (NTRS)

    Sittler Jr., E. C.; Acuna, M.; Burchell, M. J.; Coates, A.; Farrell, W.; Flasar, M.; Goldstein, B. E.; Gorevan, S.; Hartle, R. E.; Johnson, W. T. K.

    2001-01-01

    We propose a combined Titan orbiter and Titan Aerorover mission with an emphasis on both in situ and remote sensing measurements of Titan's surface, atmosphere, ionosphere, and magnetospheric interaction. The biological aspect of the Titan environment will be emphasized by the mission (i.e., search for organic materials which may include simple organics to 'amono' analogues of amino acids and possibly more complex, lightening detection and infrared, ultraviolet, and charged particle interactions with Titan's surface and atmosphere). An international mission is assumed to control costs. NASA will provide the orbiter, launch vehicle, DSN coverage and operations, while international partners will provide the Aerorover and up to 30% of the cost for the scientific instruments through collaborative efforts. To further reduce costs we propose a single PI for orbiter science instruments and a single PI for Aerorover science instruments. This approach will provide single command/data and power interface between spacecraft and orbiter instruments that will have redundant central DPU and power converter for their instruments. A similar approach could be used for the Aerorover. The mission profile will be constructed to minimize conflicts between Aerorover science, orbiter radar science, orbiter radio science, orbiter imaging science, and orbiter fields and particles (FP) science. Additional information is contained in the original extended abstract.

  20. Methane ocean on Titan?

    NASA Astrophysics Data System (ADS)

    Bell, Peter M.

    There was an impressive list of names on a recent scientific communication that argues for the existence on Titan of an ocean of liquid methane (CH4) perhaps several hundred meters deep. C. Sagan and S. Dermott with helpful comments by S. Oter, S. Ostro, S. Peale, C. Yoder, W. Thompson, S. Squyres, G. Pettengill, P. Gierasch, and B. Khare speculate that such a methanic ocean, with its Saturnian tides and its tholinian floor, should exist all over Titan's surface; it should unless, they conclude, there is the ‘distracting coincidence [that] … the position of the surface of Titan [is] … near the liquidus in the CH4phase diagram [and, consequently, there is] …almost no methane ocean at all’ (Nature, 300, 731, 1982).We know very little about Titan and its surface; the way of checking into Sagan and Dermott's ideas appears to rest on the interpretation of radar reflectivity data. Preliminary attempts to obtain radar data were made in 1979 with the 305-m Arecibo telescope, but only broad limits resulted. The next opportunity for a measurement at Arecibo comes in the 1990's. Of course, the ideal circumstance would be to send spacecraft equipped with a radar reflectometer for a Titan flyby.

  1. Hypsometry of Titan

    USGS Publications Warehouse

    Lorenz, Ralph D.; Turtle, Elizabeth P.; Stiles, Bryan; Le Gall, Alice; Hayes, Alexander; Aharonson, Oded; Wood, Charles A.; Stofan, Ellen; Kirk, Randy

    2011-01-01

    Cassini RADAR topography data are used to evaluate Titan's hypsometric profile, and to make comparisons with other planetary bodies. Titan's hypsogram is unimodal and strikingly narrow compared with the terrestrial planets. To investigate topographic extremes, a novel variant on the classic hypsogram is introduced, with a logarithmic abscissa to highlight mountainous terrain. In such a plot, the top of the terrestrial hypsogram is quite distinct from those of Mars and Venus due to the 'glacial buzz-saw' that clips terrestrial topography above the snowline. In contrast to the positive skew seen in other hypsograms, with a long tail of positive relief due to mountains, there is an indication (weak, given the limited data for Titan so far) that the Titan hypsogram appears slightly negatively skewed, suggesting a significant population of unfilled depressions. Limited data permit only a simplistic comparison of Titan topography with other icy satellites but we find that the standard deviation of terrain height (albeit at different scales) is similar to those of Ganymede and Europa.

  2. Aerocapture Systems Analysis for a Titan Mission

    NASA Technical Reports Server (NTRS)

    Lockwood, Mary K.; Queen, Eric M.; Way, David W.; Powell, Richard W.; Edquist, Karl; Starr, Brett W.; Hollis, Brian R.; Zoby, E. Vincent; Hrinda, Glenn A.; Bailey, Robert W.

    2006-01-01

    Performance projections for aerocapture show a vehicle mass savings of between 40 and 80%, dependent on destination, for an aerocapture vehicle compared to an all-propulsive chemical vehicle. In addition aerocapture is applicable to multiple planetary exploration destinations of interest to NASA. The 2001 NASA In-Space Propulsion Program (ISP) technology prioritization effort identified aerocapture as one of the top three propulsion technologies for solar system exploration missions. An additional finding was that aerocapture needed a better system definition and that supporting technology gaps needed to be identified. Consequently, the ISP program sponsored an aerocapture systems analysis effort that was completed in 2002. The focus of the effort was on aerocapture at Titan with a rigid aeroshell system. Titan was selected as the initial destination for the study due to potential interest in a follow-on mission to Cassini/Huygens. Aerocapture is feasible, and the performance is adequate, for the Titan mission and it can deliver 2.4 times more mass to Titan than an all-propulsive system for the same launch vehicle.

  3. Interim salt disposition program macrobatch 6 tank 21H qualification monosodium titanate and cesium mass transfer tests

    SciTech Connect

    Washington, A. L. II; Peters, T. B.; Fink, S. D.

    2013-02-25

    Savannah River National Laboratory (SRNL) performed experiments on qualification material for use in the Interim Salt Disposition Program (ISDP) Batch 6 processing. This qualification material was a set of six samples from Tank 21H in October 2012. This sample was used as a real waste demonstration of the Actinide Removal Process (ARP) and the Extraction-Scrub-Strip (ESS) tests process. The Tank 21H sample was contacted with a reduced amount (0.2 g/L) of MST and characterized for strontium and actinide removal at 0 and 8 hour time intervals in this salt batch. {sup 237}Np and {sup 243}Am were both observed to be below detection limits in the source material, and so these results are not reported in this report. The plutonium and uranium samples had decontamination factor (DF) values that were on par or slightly better than we expected from Batch 5. The strontium DF values are slightly lower than expected but still in an acceptable range. The Extraction, Scrub, and Strip (ESS) testing demonstrated cesium removal, stripping and scrubbing within the acceptable range. Overall, the testing indicated that cesium removal is comparable to prior batches at MCU.

  4. Cryovolcanic Features on Titan

    NASA Astrophysics Data System (ADS)

    Lopes, R. M. C.; Stofan, E. R.; Kirk, R. L.; Mitchell, K. L.; LeGall, A.; Barnes, J. W.; Hayes, A.; Kargel, J.; Radebaugh, J.; Janssen, M. A.; Neish, C. D.; Wood, C.; Wall, S. D.; Lunine, J. I.; Malaska, M. J.

    2013-09-01

    We present evidence to support the cryovolcanic origin of some features, which includes the deepest pit known on Titan (Sotra Patera) and some of the highest mountains (Doom and Erebor Montes). We interpret this region to be a cryovolcanic complex of multiple cones, craters, and flows. Elsewhere, a circular feature, approximately 100 km across, is morphologically similar to a laccolith, showing a cross pattern interpreted to be extensional fractures. However, we find that some other previously supposed cryovolcanic features were likely formed by other processes. We discuss implications for eruption style and composition of cryovolcanism on Titan. Our analysis shows the great value of combining data sets when interpreting Titan's geology and in particular stresses the value of topographic data.

  5. The tides of Titan.

    PubMed

    Iess, Luciano; Jacobson, Robert A; Ducci, Marco; Stevenson, David J; Lunine, Jonathan I; Armstrong, John W; Asmar, Sami W; Racioppa, Paolo; Rappaport, Nicole J; Tortora, Paolo

    2012-07-27

    We have detected in Cassini spacecraft data the signature of the periodic tidal stresses within Titan, driven by the eccentricity (e = 0.028) of its 16-day orbit around Saturn. Precise measurements of the acceleration of Cassini during six close flybys between 2006 and 2011 have revealed that Titan responds to the variable tidal field exerted by Saturn with periodic changes of its quadrupole gravity, at about 4% of the static value. Two independent determinations of the corresponding degree-2 Love number yield k(2) = 0.589 ± 0.150 and k(2) = 0.637 ± 0.224 (2σ). Such a large response to the tidal field requires that Titan's interior be deformable over time scales of the orbital period, in a way that is consistent with a global ocean at depth.

  6. The meteorology of Titan

    NASA Technical Reports Server (NTRS)

    Flasar, F. M.; Conrath, Barney J.

    1992-01-01

    Current knowledge of Titan's meteorology is reviewed, including diagnostic inferences of the large scale wind field and prognostic studies of thermal and momentum balances. Titan's winds were largely inferred from temperature maps whose spatial coverage is incomplete. The inferred winds are cyclostrophic, approximately 75 m/s in the upper stratosphere. The direction of the winds is ambiguous from the temperature data, but arguments based on the spin up of a planetary atmosphere from an initial state of rest strongly suggest that Titan's winds blow predominantly in the direction of the planetary rotation. Stratospheric temperatures exhibit a north-south asymmetry, suggesting that seasonal variations are controlled by a dynamical inertia associated with the need to transport angular momentum as well as heat. A consideration of the global angular momentum balance indicates that the zonally averaged winds near the surface are approximately 0.3 m/s.

  7. Models of Titan's Ionosphere

    NASA Astrophysics Data System (ADS)

    Robertson, I. P.; Cravens, T. E.; Waite, J. H.; Wahlund, J.; Yelle, R. V.; Vuitton, V.; Coates, A.; Magee, B.; Gell, D. A.

    2007-12-01

    During the TA and T18 encounters with Titan, in situ measurements were made of Titan's atmosphere and ionosphere by several instruments on board the Cassini Orbiter, including the Ion and Neutral Mass Spectrometer (INMS), the Langmuir probe on the Cassini Radio and Plasma Wave Experiment (RPWS), and the Cassini Plasma Spectrometer Subsystem (CAPS). Both of these encounters were on the day as well as the night side of Titan. The model uses neutral densities measured by the INMS instrument and the electron temperature was measured by the RPWS instrument. The model also includes energetic electron fluxes measured by the CAPS instrument, which act as an important source of ionization on the night side. The modeled ion densities are compared with densities measured by INMS in its Open Source mode.

  8. The tides of Titan.

    PubMed

    Iess, Luciano; Jacobson, Robert A; Ducci, Marco; Stevenson, David J; Lunine, Jonathan I; Armstrong, John W; Asmar, Sami W; Racioppa, Paolo; Rappaport, Nicole J; Tortora, Paolo

    2012-07-27

    We have detected in Cassini spacecraft data the signature of the periodic tidal stresses within Titan, driven by the eccentricity (e = 0.028) of its 16-day orbit around Saturn. Precise measurements of the acceleration of Cassini during six close flybys between 2006 and 2011 have revealed that Titan responds to the variable tidal field exerted by Saturn with periodic changes of its quadrupole gravity, at about 4% of the static value. Two independent determinations of the corresponding degree-2 Love number yield k(2) = 0.589 ± 0.150 and k(2) = 0.637 ± 0.224 (2σ). Such a large response to the tidal field requires that Titan's interior be deformable over time scales of the orbital period, in a way that is consistent with a global ocean at depth. PMID:22745254

  9. Dislocation injection in strontium titanate by femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Titus, Michael S.; Echlin, McLean P.; Gumbsch, Peter; Pollock, Tresa M.

    2015-08-01

    Femtosecond laser ablation is used in applications which require low damage surface treatments, such as serial sectioning, spectroscopy, and micromachining. However, dislocations are generated by femtosecond laser-induced shockwaves and consequently have been studied in strontium titanate (STO) using transmission electron microscopy (TEM) and electron backscatter diffraction analysis. The laser ablated surfaces in STO exhibit dislocation structures that are indicative of those produced by uniaxial compressive loading. TEM analyses of dislocations present just below the ablated surface confirm the presence of ⟨110 ⟩ dislocations that are of approximately 35° mixed character. The penetration depth of the dislocations varied with grain orientation relative to the surface normal, with a maximum depth of 1.5 μm. Based on the critical resolved shear stress of STO crystals, the approximate shockwave pressures experienced beneath the laser irradiated surface are reported.

  10. Titanic Weather Forecasting

    NASA Astrophysics Data System (ADS)

    2004-04-01

    New Detailed VLT Images of Saturn's Largest Moon Optimizing space missions Titan, the largest moon of Saturn was discovered by Dutch astronomer Christian Huygens in 1655 and certainly deserves its name. With a diameter of no less than 5,150 km, it is larger than Mercury and twice as large as Pluto. It is unique in having a hazy atmosphere of nitrogen, methane and oily hydrocarbons. Although it was explored in some detail by the NASA Voyager missions, many aspects of the atmosphere and surface still remain unknown. Thus, the existence of seasonal or diurnal phenomena, the presence of clouds, the surface composition and topography are still under debate. There have even been speculations that some kind of primitive life (now possibly extinct) may be found on Titan. Titan is the main target of the NASA/ESA Cassini/Huygens mission, launched in 1997 and scheduled to arrive at Saturn on July 1, 2004. The ESA Huygens probe is designed to enter the atmosphere of Titan, and to descend by parachute to the surface. Ground-based observations are essential to optimize the return of this space mission, because they will complement the information gained from space and add confidence to the interpretation of the data. Hence, the advent of the adaptive optics system NAOS-CONICA (NACO) [1] in combination with ESO's Very Large Telescope (VLT) at the Paranal Observatory in Chile now offers a unique opportunity to study the resolved disc of Titan with high sensitivity and increased spatial resolution. Adaptive Optics (AO) systems work by means of a computer-controlled deformable mirror that counteracts the image distortion induced by atmospheric turbulence. It is based on real-time optical corrections computed from image data obtained by a special camera at very high speed, many hundreds of times each second (see e.g. ESO Press Release 25/01 , ESO PR Photos 04a-c/02, ESO PR Photos 19a-c/02, ESO PR Photos 21a-c/02, ESO Press Release 17/02, and ESO Press Release 26/03 for earlier NACO

  11. Diurnal variations of Titan

    NASA Astrophysics Data System (ADS)

    Cui, J.; Galand, M.; Yelle, R. V.; Vuitton, V.; Wahlund, J.-E.; Lavvas, P. P.; Mueller-Wodarg, I. C. F.; Kasprzak, W. T.; Waite, J. H.

    2009-04-01

    We present our analysis of the diurnal variations of Titan's ionosphere (between 1,000 and 1,400 km) based on a sample of Ion Neutral Mass Spectrometer (INMS) measurements in the Open Source Ion (OSI) mode obtained from 8 close encounters of the Cassini spacecraft with Titan. Though there is an overall ion depletion well beyond the terminator, the ion content on Titan's nightside is still appreciable, with a density plateau of ~700 cm-3 below ~1,300 km. Such a plateau is associated with the combination of distinct diurnal variations of light and heavy ions. Light ions (e.g. CH5+, HCNH+, C2H5+) show strong diurnal variation, with clear bite-outs in their nightside distributions. In contrast, heavy ions (e.g. c-C3H3+, C2H3CNH+, C6H7+) present modest diurnal variation, with significant densities observed on the nightside. We propose that the distinctions between light and heavy ions are associated with their different chemical loss pathways, with the former primarily through "fast" ion-neutral chemistry and the latter through "slow" electron dissociative recombination. The INMS data suggest day-to-night transport as an important source of ions on Titan's nightside, to be distinguished from the conventional scenario of auroral ionization by magnetospheric particles as the only ionizing source on the nightside. This is supported by the strong correlation between the observed night-to-day ion density ratios and the associated ion lifetimes. We construct a time-dependent ion chemistry model to investigate the effects of day-to-night transport on the ionospheric structures of Titan. The predicted diurnal variation has similar general characteristics to those observed, with some apparent discrepancies which could be reconciled by imposing fast horizontal thermal winds in Titan's upper atmosphere.

  12. Impact craters on Titan

    USGS Publications Warehouse

    Wood, C.A.; Lorenz, R.; Kirk, R.; Lopes, R.; Mitchell, Ken; Stofan, E.

    2010-01-01

    Five certain impact craters and 44 additional nearly certain and probable ones have been identified on the 22% of Titan's surface imaged by Cassini's high-resolution radar through December 2007. The certain craters have morphologies similar to impact craters on rocky planets, as well as two with radar bright, jagged rims. The less certain craters often appear to be eroded versions of the certain ones. Titan's craters are modified by a variety of processes including fluvial erosion, mass wasting, burial by dunes and submergence in seas, but there is no compelling evidence of isostatic adjustments as on other icy moons, nor draping by thick atmospheric deposits. The paucity of craters implies that Titan's surface is quite young, but the modeled age depends on which published crater production rate is assumed. Using the model of Artemieva and Lunine (2005) suggests that craters with diameters smaller than about 35 km are younger than 200 million years old, and larger craters are older. Craters are not distributed uniformly; Xanadu has a crater density 2-9 times greater than the rest of Titan, and the density on equatorial dune areas is much lower than average. There is a small excess of craters on the leading hemisphere, and craters are deficient in the north polar region compared to the rest of the world. The youthful age of Titan overall, and the various erosional states of its likely impact craters, demonstrate that dynamic processes have destroyed most of the early history of the moon, and that multiple processes continue to strongly modify its surface. The existence of 24 possible impact craters with diameters less than 20 km appears consistent with the Ivanov, Basilevsky and Neukum (1997) model of the effectiveness of Titan's atmosphere in destroying most but not all small projectiles. ?? 2009 Elsevier Inc.

  13. Impact craters on Titan

    USGS Publications Warehouse

    Wood, Charles A.; Lorenz, Ralph; Kirk, Randy; Lopes, Rosaly; Mitchell, Karl; Stofan, Ellen; ,

    2010-01-01

    Five certain impact craters and 44 additional nearly certain and probable ones have been identified on the 22% of Titan's surface imaged by Cassini's high-resolution radar through December 2007. The certain craters have morphologies similar to impact craters on rocky planets, as well as two with radar bright, jagged rims. The less certain craters often appear to be eroded versions of the certain ones. Titan's craters are modified by a variety of processes including fluvial erosion, mass wasting, burial by dunes and submergence in seas, but there is no compelling evidence of isostatic adjustments as on other icy moons, nor draping by thick atmospheric deposits. The paucity of craters implies that Titan's surface is quite young, but the modeled age depends on which published crater production rate is assumed. Using the model of Artemieva and Lunine (2005) suggests that craters with diameters smaller than about 35 km are younger than 200 million years old, and larger craters are older. Craters are not distributed uniformly; Xanadu has a crater density 2-9 times greater than the rest of Titan, and the density on equatorial dune areas is much lower than average. There is a small excess of craters on the leading hemisphere, and craters are deficient in the north polar region compared to the rest of the world. The youthful age of Titan overall, and the various erosional states of its likely impact craters, demonstrate that dynamic processes have destroyed most of the early history of the moon, and that multiple processes continue to strongly modify its surface. The existence of 24 possible impact craters with diameters less than 20 km appears consistent with the Ivanov, Basilevsky and Neukum (1997) model of the effectiveness of Titan's atmosphere in destroying most but not all small projectiles.

  14. Titan's Winter Polar Vortex

    NASA Technical Reports Server (NTRS)

    Flasar, F.M.; Achterberg, R.K.; Schinder, P.J.

    2008-01-01

    Titan's atmosphere has provided an interesting study in contrasts and similarities with Earth's. While both have N$_2$ as the dominant constituent and comparable surface pressures $\\sim1$ bar, Titan's next most abundant molecule is CH$_4$, not O$_2$, and the dissociative breakup of CH$_4$ and N$_2$ by sunlight and electron impact leads to a suite of hydrocarbons and nitriles, and ultimately the photochemical smog that enshrouds the moon. In addition, with a 15.95-day period, Titan is a slow rotator compared to Earth. While the mean zonal terrestrial winds are geostrophic, Titan's are mostly cyclostrophic, whipping around the moon in as little as 1 day. Despite the different dynamical regime, Titan's winter stratosphere exhibits several characteristics that should be familiar to terrestrial meteorologists. The cold winter pole near the 1 -mbar level is circumscribed by strong winds (up to 190 m/s) that act as a barrier to mixing with airmasses at lower latitudes. There is evidence of enhancement of several organic species over the winter pole, indicating subsidence. The adiabatic heating associated with this subsidence gives rise to a warm anomaly at the 0.01-mbar level, raising the stratopause two scale heights above its location at equatorial latitudes. Condensate ices have been detected in Titan's lower stratosphere within the winter polar vortex from infrared spectra. Although not always unambiguously identified, their spatial distribution exhibits a sharp gradient, decreasing precipitously across the vortex away from the winter pole. The interesting question of whether there is important heterogeneous chemistry occurring within the polar vortex, analogous to that occurring in the terrestrial polar stratospheric clouds in the ozone holes, has not been addressed. The breakup of Titan's winter polar vortex has not yet been observed. On Earth, the polar vortex is nonlinearly disrupted by interaction with large-amplitude planetary waves. Large-scale waves have not

  15. Flying by Titan

    NASA Technical Reports Server (NTRS)

    Pelletier, Frederic J.; Antreasian, Peter G.; Ardalan, Shadan M.; Criddle, Kevin E.; Ionasescu, Rodica; Jacobson, Robert A.; Jones, Jeremy B.; Parcher, Daniel W.; Roth, Duane C.; Thompson, Paul F.; Vaughan, Andrew T.

    2008-01-01

    The Cassini spacecraft encounters the massive Titan about once every month. These encounters are essential to the mission as Titan is the only satellite of Saturn that can provide enough gravity assist to shape the orbit tour and allow outstanding science for many years. From a navigation point of view, these encounters provide many challenges, in particular those that fly close enough to the surface for the atmospheric drag to perturb the orbit. This paper discusses the dynamics models developed to successfully navigate Cassini and determine its trajectory. This includes the moon's gravity pull with its second degree zonal harmonics J2, the attitude thrust control perturbations and the acceleration of drag.

  16. Titan's "Hot Cross Bun": A Titan Laccolith?

    NASA Astrophysics Data System (ADS)

    Lopes, Rosaly M. C.; Stofan, E. R.; Wall, S. D.; Wood, C.; Kirk, R. L.; Lucas, A.; Mitchell, K. L.; Lunine, J. I.; Turtle, E. P.; Radebaugh, J.; Malaska, M.; Cassini RADAR Team

    2012-10-01

    Cassini’s RADAR instrument acquired Synthetic Aperture Radar data during the T83 flyby on May 22, 2012. The data showed a feature centered at 38.5N, 203W that resembles a “hot cross bun”. This type of feature has not been seen on Titan before, even though 52% of Titan’s surface has been imaged using SAR. The feature, approximately 100 km across, is mostly radar bright but the cross pattern, interpreted to be extensional fractures, located roughly at the center of the brighter area, appears darker at radar wavelengths (2.3 cm). Radar illumination of the image indicates that the fractures are lower in elevation than the surrounding bright region. The morphology of the region is markedly similar to that of a 30-km dome-shaped feature on Venus that lies at the summit of the Kunapipi volcano. The Venus feature is interpreted to be the result of intrusion of magma at the summit of the volcano [1]. A similar feature, interpreted as a laccolith, is seen on the Moon near the crater Ramsden [2]. The lunar feature, imaged by the Lunar Reconnaissance Orbiter, shows the cross-shaped depression over a 300 m high rise. No topographic data for the feature on Titan are available at this time, but the morphology seen by the SAR data suggests that the feature may have been formed by material pushing up from below. Laccoliths form when an igneous intrusion splits apart two strata, resulting in a domeline structure. This previously unknown type of structure on Titan may be yet another indication of cryovolcanism. [1] Stofan, E.R., et al, Icarus, 152, 75-95, 2001. [2] Wichman, R.W. and Schultz, P. H. (1996). Icarus, 122, Issue 1, July 1996, pages 193-199. doi:10.1006/icar.1996.0118

  17. ICES ON TITAN: LABORATORY MEASUREMENTS THAT COMPLEMENT THE HUYGENS PROBE

    SciTech Connect

    J. ROBINSON; ET AL

    2000-08-01

    This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The composition of the cold bodies in the outer solar system may hold some of the key molecular clues concerning the composition of the prestellax molecular cloud that gave rise to the solar system. We studied the physical chemistry and heterogeneous (gas/surface) reactivity of extraterrestrial ice analogs of the surfaces of Saturn's moon Titan. This program coupled our surface spectroscopic techniques with physical adsorption measurements. We addressed several of the pressing questions regarding Titan such as: Is storage of hydrocarbons in Titan's water ice crust feasible? Do heterogeneous processes influence the atmospheric chemical composition of Titan? Are phase transitions to be expected? These data can be incorporated into photochemical models with the goal of improved modeling of the chemical composition and meteorology of Titan's atmosphere. Titan will be probed by the Cassini-Huygens Mission. Our results on Titan ice analogs can be used to help interpret the mission data.

  18. Rivers on Titan - numerical modelling of sedimentary structures

    NASA Astrophysics Data System (ADS)

    Misiura, Katarzyna; Czechowski, Leszek

    2016-07-01

    flow and of the sedimentation on Titan and on the Earth. Our preliminary results indicate that suspended load is the main way of transport in simulated Titan's conditions. We also indicate that braided rivers appears for larger range of slope on Titan (e.g. S=0.01-0.04) than on Earth (e.g. S=0.004-0.009). Also, for the same type of river, the grain size on Titan is at least 10 times larger than on Earth (1 cm for Titan versus 1 mm for the Earth). It is very interesting that on Titan braided rivers appear even for very little discharge (e.g. Q=30m3/s) and for very large grain size (e.g. 10 cm). In the future we plan the experimental modelling in sediment basin to confirm results from computer modelling. Acknowledgements We are very grateful to Yaoxin Zhang and Yafei Jia from National Center for Computational Hydroscience and Engineering for providing their program - CCHE2D. References [1] Misiura, K., Czechowski, L., 2015. Numerical modelling of sedimentary structures in rivers on Earth and Titan. Geological Quarterly, 59(3): 565-580. [2] Witek, P., Czechowski, L., 2015. Dynamical modeling of river deltas on Titan and Earth. Planet. Space. Sci., 105: 65-79.

  19. The lakes of Titan

    USGS Publications Warehouse

    Stofan, E.R.; Elachi, C.; Lunine, J.I.; Lorenz, R.D.; Stiles, B.; Mitchell, K.L.; Ostro, S.; Soderblom, L.; Wood, C.; Zebker, H.; Wall, S.; Janssen, M.; Kirk, R.; Lopes, R.; Paganelli, F.; Radebaugh, J.; Wye, L.; Anderson, Y.; Allison, M.; Boehmer, R.; Callahan, P.; Encrenaz, P.; Flamini, E.; Francescetti, G.; Gim, Y.; Hamilton, G.; Hensley, S.; Johnson, W.T.K.; Kelleher, K.; Muhleman, D.; Paillou, P.; Picardi, G.; Posa, F.; Roth, L.; Seu, R.; Shaffer, S.; Vetrella, S.; West, R.

    2007-01-01

    The surface of Saturn's haze-shrouded moon Titan has long been proposed to have oceans or lakes, on the basis of the stability of liquid methane at the surface. Initial visible and radar imaging failed to find any evidence of an ocean, although abundant evidence was found that flowing liquids have existed on the surface. Here we provide definitive evidence for the presence of lakes on the surface of Titan, obtained during the Cassini Radar flyby of Titan on 22 July 2006 (T16). The radar imaging polewards of 70?? north shows more than 75 circular to irregular radar-dark patches, in a region where liquid methane and ethane are expected to be abundant and stable on the surface. The radar-dark patches are interpreted as lakes on the basis of their very low radar reflectivity and morphological similarities to lakes, including associated channels and location in topographic depressions. Some of the lakes do not completely fill the depressions in which they lie, and apparently dry depressions are present. We interpret this to indicate that lakes are present in a number of states, including partly dry and liquid-filled. These northern-hemisphere lakes constitute the strongest evidence yet that a condensable-liquid hydrological cycle is active in Titan's surface and atmosphere, in which the lakes are filled through rainfall and/or intersection with the subsurface 'liquid methane' table. ??2007 Nature Publishing Group.

  20. Sinking with the Titanic

    NASA Astrophysics Data System (ADS)

    Bagnoli, Franco

    2015-03-01

    In the Titanic movie, when the rear part of the ship is about to sink, Jack Dawson (Leonardo DiCaprio) says to Rose DeWitt Bukater (Kate Winslet) to get ready to swim, because the sinking body will suck them into the abysses. Is this sucking phenomenon really happening? And, if so, why?

  1. Radar reflectivity of titan.

    PubMed

    Muhleman, D O; Grossman, A W; Butler, B J; Slade, M A

    1990-05-25

    The present understanding of the atmosphere and surface conditions on Saturn's largest moon, Titan, including the stability of methane, and an application of thermodynamics leads to a strong prediction of liquid hydrocarbons in an ethane-methane mixture on the surface. Such a surface would have nearly unique microwave reflection properties due to the low dielectric constant. Attempts were made to obtain reflections at a wavelength of 3.5 centimeters by means of a 70-meter antenna in California as the transmitter and the Very Large Array in New Mexico as the receiving instrument. Statistically significant echoes were obtained that show Titan is not covered with a deep, global ocean of ethane, as previously thought. The experiment yielded radar cross sections normalized by the Titan disk of 0.38 +/- 0.15, 0.78 +/- 0.15, and 0.25 +/- 0.15 on three consecutive nights during which the sub-Earth longitude on Titan moved 50 degrees. The result for the combined data for the entire experiment is 0.35 +/- 0.08. The cross sections are very high, most consistent with those of the Galilean satellites; no evidence of the putative liquid ethane was seen in the reflection data. A global ocean as shallow as about 200 meters would have exhibited reflectivities smaller by an order of magnitude, and below the detection limit of the experiment. The measured emissivity at similar wavelengths of about 0.9 is somewhat inconsistent with the high reflectivity.

  2. Possible evidence a Titan-generated Nitrogen Torus in Saturn's Magnetosphere (Invited)

    NASA Astrophysics Data System (ADS)

    Smith, H. T.; Rymer, A. M.; Johnson, R. E.; Lewis, G.; Coates, A. J.; Mitchell, D. G.; Young, D. T.

    2013-12-01

    Saturn's largest moon, Titan, possesses no intrinsic magnetic field which leaves its dense nitrogen-rich atmosphere relatively unprotected from direct interaction Saturn's magnetosphere. Therefore, it was logically assumed that nitrogen particles would escape from Titan's atmosphere and form a large toriodal gas cloud near Titan's orbit (in the outer magnetosphere) constituting the dominant species in the magnetosphere. Cassini observations detected nitrogen ions, however these particles exist in the inner magnetosphere and water-group particles (from Enceladus' plumes) actually dominate Saturn's heavy magnetospheric particle population. In fact, pick-up oxygen ions from Enceladus are much more abundant than nitrogen in Titan's orbit. These results appear inconsistent with the expectation that Titan's exposed atmosphere should provide a significant source of heavy particles to Saturn's magnetosphere. Resolving this inconsistency could provide import insight into atmospheric loss. Subsequent modeling and observations indicate that the observed nitrogen in the inner magnetosphere cannot be entirely produced by Enceladus. Considering these results combined with it being hard to imagine that nitrogen would not be escaping from Titan, we have continued to explore the possible presence of a nitrogen torus at Titan's orbit. In this talk, we using modeling results and observations to support a theory explaining 'torus erosion' which limits the ability to detect a Titan torus. Using these results, we also present the first detections of nitrogen in Titan's orbit possibly originating from a Titan torus. This work is supported by the NASA Cassini Data Analysis Program and NASA JPL contract 1243218 for Cassini MIMI and CAPS investigation.

  3. Investigating Titan's Atmospheric Chemistry at Low Temperature with the Titan Haze Simulation Experiment

    NASA Astrophysics Data System (ADS)

    Sciamma-O'Brien, E. M.; Salama, F.

    2012-12-01

    in the THS experiment and can be analyzed by Gas Chromatography-Mass Spectrometry (GC-MS), Scanning Electron Microscopy (SEM) and IR spectroscopy. Here we present the results of a systematic mass spectrometry study using N2-based, Ar-based and N2-CH4(90:10)-based mixtures with several hydrocarbon precursors to investigate specific pathways associated with the presence of these trace elements in Titan's atmosphere. These results show the uniqueness of the THS experiment to help understand the first and intermediate steps of Titan's atmospheric chemistry as well as specific chemical pathways leading to Titan's haze formation. We will also present the results of ex situ analyses performed on tholins produced in the THS experiment with different gas mixtures, and compare them to tholin films produced in a static photochemistry cell using VUV instead of plasma as the energy source for the chemistry. Acknowledgments This research is supported by NASA SMD (Planetary Atmospheres Program). E.S.O. acknowledges the support of the NASA Postdoctoral Program (NPP) and thanks Claire L. Ricketts for the help and discussions with regard to the photochemistry cell. Finally, the authors acknowledge the technical support of R. Walker (NASA ARC).

  4. Poster 14: Explorer of Enceladus and Titan (E2T)

    NASA Astrophysics Data System (ADS)

    Mitri, Giuseppe; Tobie, Gabriel; Postberg, Frank; Soderblom, Jason M.; Wurz, Peter; Barnes, Jason W.; Berga, Marco; Coustenis, Athena; D'Ottavio, Andrea Hayes, Alexander G.; Hayne, Paul O.; Lebreton, Jean-Pierre; Lorenz, Ralph D.; Martelli, Andrea; Petropoulos, Anastassios E.; Yen, Chen-wan L.; Reh, Kim R.; Sotin, Christophe; Srama, Ralf; Tortora, Paolo

    2016-06-01

    solid and volatile species. High-resolution IR imaging will reveal Titan's surface and Enceladus's fractured SPT and plume in detail unattainable by the Cassini mission, allowing us to investigate the processes that are transporting and transforming organic materials on the surface of Titan, and constrain the mechanisms controlling, and the energy dissipated by, Enceladus' plume. The proposed mission will address key scientific questions regarding extraterrestrial habitability, abiotic/prebiotic chemistry and emergence of life, which are among the highest priorities of ESA's Cosmic Vision program.

  5. Mission Techniques for Exploring Saturn's icy moons Titan and Enceladus

    NASA Astrophysics Data System (ADS)

    Reh, Kim; Coustenis, Athena; Lunine, Jonathan; Matson, Dennis; Lebreton, Jean-Pierre; Vargas, Andre; Beauchamp, Pat; Spilker, Tom; Strange, Nathan; Elliott, John

    2010-05-01

    The future exploration of Titan is of high priority for the solar system exploration community as recommended by the 2003 National Research Council (NRC) Decadal Survey [1] and ESA's Cosmic Vision Program themes. Cassini-Huygens discoveries continue to emphasize that Titan is a complex world with very many Earth-like features. Titan has a dense, nitrogen atmosphere, an active climate and meteorological cycles where conditions are such that the working fluid, methane, plays the role that water does on Earth. Titan's surface, with lakes and seas, broad river valleys, sand dunes and mountains was formed by processes like those that have shaped the Earth. Supporting this panoply of Earth-like processes is an ice crust that floats atop what might be a liquid water ocean. Furthermore, Titan is rich in very many different organic compounds—more so than any place in the solar system, except Earth. The Titan Saturn System Mission (TSSM) concept that followed the 2007 TandEM ESA CV proposal [2] and the 2007 Titan Explorer NASA Flagship study [3], was examined [4,5] and prioritized by NASA and ESA in February 2009 as a mission to follow the Europa Jupiter System Mission. The TSSM study, like others before it, again concluded that an orbiter, a montgolfiѐre hot-air balloon and a surface package (e.g. lake lander, Geosaucer (instrumented heat shield), …) are very high priority elements for any future mission to Titan. Such missions could be conceived as Flagship/Cosmic Vision L-Class or as individual smaller missions that could possibly fit within NASA's New Frontiers or ESA's Cosmic Vision M-Class budgets. As a result of a multitude of Titan mission studies, several mission concepts have been developed that potentially fit within various cost classes. Also, a clear blueprint has been laid out for early efforts critical toward reducing the risks inherent in such missions. The purpose of this paper is to provide a brief overview of potential Titan (and Enceladus) mission

  6. Water Deposition into Titan atmosphere from Saturn's E-ring

    NASA Astrophysics Data System (ADS)

    Juhasz, A.; Horanyi, M.; Kempf, S.; Srama, R.

    2013-12-01

    Cassini's discovery of the geologically active regions on the south polar region of Enceladus allowed the identification of these active plumes as the primary source of Saturn's E-ring. Micron and submicron sized ice particles are supplied from the plumes to sustain the entire E-ring. In situ measurements by the Cassini Cosmic Dust Analyzer (CDA) also led to the recognition that the E-ring extends way beyond its originally recognized limits of 4 - 8 Saturn radii (Rs), reaching beyond 20 Rs, engulfing Titan, Saturn's largest moon. Ice grains entrained in the plumes experience radiation pressure and plasma drag perturbations and their orbits slowly evolve outward. Simultaneously, the ice particles are exposed to energetic ion bombardment, leading to their mass loss due to sputtering. Initially micron sized particles from Enceladus take about 500 years to reach the orbit of Titan, arriving there as approximately 0.1-0.3 micron sized particles. Due to their large eccentricities, these small grains enter Titan's atmosphere with speeds v > 1 km/s,sufficiently fast to ablate, delivering on the order of 5 g/s of water. This presentation will discuss the resulting profiles of water vapor deposition rates as function of altitude in Titan's atmosphere.

  7. Titanates and Titanate-Metal Compounds in Biological Contexts

    PubMed Central

    Chen, Yen-Wei; Drury, Jeanie L.; Chung, Whasun Oh; Hobbs, David T.; Wataha, John C.

    2015-01-01

    Metal ions are notorious environmental contaminants, some causing toxicity at exquisitely low (ppm-level) concentrations. Yet, the redox properties of metal ions make them attractive candidates for bio-therapeutics. Titanates are insoluble particulate compounds of titanium and oxygen with crystalline surfaces that bind metal ions; these compounds offer a means to scavenge metal ions in environmental contexts or deliver them in therapeutic contexts while limiting systemic exposure and toxicity. In either application, the toxicological properties of titanates are crucial. To date, the accurate measurement of the in vitro toxicity of titanates has been complicated by their particulate nature, which interferes with many assays that are optical density (OD)-dependent, and at present, little to no in vivo titanate toxicity data exist. Compatibility data garnered thus far for native titanates in vitro are inconsistent and lacking in mechanistic understanding. These data suggest that native titanates have little toxicity toward several oral and skin bacteria species, but do suppress mammalian cell metabolism in a cells-pecific manner. Titanate compounds bind several types of metal ions, including some common environmental toxins, and enhance delivery to bacteria or cells. Substantial work remains to address the practical applicability of titanates. Nevertheless, titanates have promise to serve as novel vehicles for metal-based therapeutics or as a new class of metal scavengers for environmental applications. PMID:26430701

  8. Ablative Thermal Protection: An Overview

    NASA Technical Reports Server (NTRS)

    Laub, Bernie

    2003-01-01

    Contents include the following: Why ablative thermal protections - TPS. Ablative TPS chronology: strategic reentry systems, solid rocket motor nozzles, space (manned missions and planetary entry probes). Ablation mechanisms. Ablation material testing. Ablative material testing.

  9. Titan's global geologic processes

    NASA Astrophysics Data System (ADS)

    Malaska, Michael; Lopes, Rosaly M. C.; Schoenfeld, Ashley; Birch, Samuel; Hayes, Alexander; Williams, David A.; Solomonidou, Anezina; Janssen, Michael A.; Le Gall, Alice; Soderblom, Jason M.; Neish, Catherine; Turtle, Elizabeth P.; Cassini RADAR Team

    2016-10-01

    We have mapped the Cassini SAR imaged areas of Saturn's moon Titan in order to determine the geological properties that modify the surface [1]. We used the SAR dataset for mapping, but incorporated data from radiometry, VIMS, ISS, and SARTopo for terrain unit determination. This work extends our analyses of the mid-latitude/equatorial Afekan Crater region [2] and in the southern and northern polar regions [3]. We placed Titan terrains into six broad terrain classes: craters, mountain/hummocky, labyrinth, plains, dunes, and lakes. We also extended the fluvial mapping done by Burr et al. [4], and defined areas as potential cryovolcanic features [5]. We found that hummocky/mountainous and labyrinth areas are the oldest units on Titan, and that lakes and dunes are among the youngest. Plains units are the largest unit in terms of surface area, followed by the dunes unit. Radiometry data suggest that most of Titan's surface is covered in high-emissivity materials, consistent with organic materials, with only minor exposures of low-emissivity materials that are consistent with water ice, primarily in the mountain and hummocky areas and crater rims and ejecta [6, 7]. From examination of terrain orientation, we find that landscape evolution in the mid-latitude and equatorial regions is driven by aeolian processes, while polar landscapes are shaped by fluvial, lacrustine, and possibly dissolution or volatilization processes involving cycling organic materials [3, 8]. Although important in deciphering Titan's terrain evolution, impact processes play a very minor role in the modification of Titan's landscape [9]. We find no evidence for large-scale aqueous cryovolcanic deposits.References: [1] Lopes, R.M.C. et al. (2010) Icarus, 205, 540–558. [2] Malaska, M.J. et al. (2016) Icarus, 270, 130–161. [3] Birch et al., in revision. [4] Burr et al. (2013) GSA Bulletin 125, 299–321. [5] Lopes et al. JGR: Planets, 118, 1–20. [6] Janssen et al., (2009) Icarus, 200, 222–239. [7

  10. Thermal stability of titanate nanorods and titania nanowires formed from titanate nanotubes by heating

    SciTech Connect

    Brunatova, Tereza; Matej, Zdenek; Oleynikov, Peter; Vesely, Josef; Danis, Stanislav; Popelkova, Daniela; Kuzel, Radomir

    2014-12-15

    The structure of titanate nanowires was studied by a combination of powder X-ray diffraction (XRD) and 3D precession electron diffraction. Titania nanowires and titanate nanorods were prepared by heating of titanate nanotubes. The structure of final product depended on heating conditions. Titanium nanotubes heated in air at a temperature of 850 °C decomposed into three phases — Na{sub 2}Ti{sub 6}O{sub 13} (nanorods) and two phases of TiO{sub 2} — anatase and rutile. At higher temperatures the anatase form of TiO{sub 2} transforms into rutile and the nanorods change into rutile nanoparticles. By contrast, in the vacuum only anatase phases of TiO{sub 2} were obtained by heating at 900 °C. The anatase transformation into rutile began only after a longer time of heating at 1000 °C. For the description of anisotropic XRD line broadening in the total powder pattern fitting by the program MSTRUCT a model of nanorods with elliptical base was included in the software. The model parameters — rod length, axis size of the elliptical base, the ellipse flattening parameter and twist of the base could be refined. Variation of particle shapes with temperature was found. - Highlights: • Titanate nanotubes changed to particles of TiO{sub 2} and nanorods of Na{sub 2}Ti{sub 6}O{sub 13} at 850 °C. • With heating time and temperature nanorods transformed to rutile nanoparticles. • X-ray diffraction powder pattern fitting indicated an elliptical shape of nanorod base. • No transition of titanate nanotubes to Na{sub 2}Ti{sub 6}O{sub 13} was found after heating in vacuum. • Heating of titanate nanotubes in vacuum leads to appearance of anatase nanowires.

  11. Lead zirconate titanate ceramics

    SciTech Connect

    Walker, B.E. Jr.

    1986-12-02

    This patent describes a lead zirconate titanate (PZT) piezoelectric ceramic composition which, based on total composition weight, consists essentially of a solid solution of lead zirconate and lead titanate in a PbZrO/sub 3/:PbTiO/sub 3/ ratio from about 0.505:0.495 to about 0.54:0.46; a halide salt selected from the group consisting of fluorides and chlorides of alkali metal and alkaline earth elements and mixtures thereof except for francium and radium in an amount from about 0.5 to 2 weight percent; and an oxide selected from the group consisting of magnesium, barium, scandium, aluminum, lanthanum, praesodynium, neodymium, samarium, and mixtures thereof in an amount from about 0.5 to about 6 weight percent, the relative amount of oxide being from about 1 to about 4 times that of the halide.

  12. Organic chemistry on Titan

    NASA Technical Reports Server (NTRS)

    Chang, S.; Scattergood, T.; Aronowitz, S.; Flores, J.

    1979-01-01

    Features taken from various models of Titan's atmosphere are combined in a working composite model that provides environmental constraints within which different pathways for organic chemical synthesis are determined. Experimental results and theoretical modeling suggest that the organic chemistry of the satellite is dominated by two processes: photochemistry and energetic particle bombardment. Photochemical reactions of CH4 in the upper atmosphere can account for the presence of C2 hydrocarbons. Reactions initiated at various levels of the atmosphere by cosmic rays, Saturn 'wind', and solar wind particle bombardment of a CH4-N2 atmospheric mixture can account for the UV-visible absorbing stratospheric haze, the reddish appearance of the satellite, and some of the C2 hydrocarbons. In the lower atmosphere photochemical processes will be important if surface temperatures are sufficiently high for gaseous NH3 to exist. It is concluded that the surface of Titan may contain ancient or recent organic matter (or both) produced in the atmosphere.

  13. Titanic exploration with GIS

    USGS Publications Warehouse

    Kerski, J.J.

    2004-01-01

    To help teachers and students investigate one of the world's most famous historical events using the geographic perspective and GIS tools and methods, the U.S. Geological Survey (USGS) created a set of educational lessons based on the RMS Titanic's April 1912 sailing. With these lessons, student researchers can learn about latitude and longitude, map projections, ocean currents, databases, maps, and images through the analysis of the route, warnings, sinking, rescue, and eventual discovery of the submerged ocean liner in 1985. They can also consider the human and physical aspects of the maiden voyage in the North Atlantic Ocean at a variety of scales, from global to regional to local. Likewise, their investigations can reveal how the sinking of the Titanic affected future shipping routes.

  14. RADAR Reveals Titan Topography

    NASA Technical Reports Server (NTRS)

    Kirk, R. L.; Callahan, P.; Seu, R.; Lorenz, R. D.; Paganelli, F.; Lopes, R.; Elachi, C.

    2005-01-01

    The Cassini Titan RADAR Mapper is a K(sub u)-band (13.78 GHz, lambda = 2.17 cm) linear polarized RADAR instrument capable of operating in synthetic aperture (SAR), scatterometer, altimeter and radiometer modes. During the first targeted flyby of Titan on 26 October, 2004 (referred to as Ta) observations were made in all modes. Evidence for topographic relief based on the Ta altimetry and SAR data are presented here. Additional SAR and altimetry observations are planned for the T3 encounter on 15 February, 2005, but have not been carried out at this writing. Results from the T3 encounter relevant to topography will be included in our presentation. Data obtained in the Ta encounter include a SAR image swath

  15. The Tides of Titan

    NASA Astrophysics Data System (ADS)

    Iess, Luciano; Jacobson, Robert A.; Ducci, Marco; Stevenson, David J.; Lunine, Jonathan I.; Armstrong, John W.; Asmar, Sami W.; Racioppa, Paolo; Rappaport, Nicole J.; Tortora, Paolo

    2012-07-01

    We have detected in Cassini spacecraft data the signature of the periodic tidal stresses within Titan, driven by the eccentricity (e = 0.028) of its 16-day orbit around Saturn. Precise measurements of the acceleration of Cassini during six close flybys between 2006 and 2011 have revealed that Titan responds to the variable tidal field exerted by Saturn with periodic changes of its quadrupole gravity, at about 4% of the static value. Two independent determinations of the corresponding degree-2 Love number yield k2 = 0.589 ± 0.150 and k2 = 0.637 ± 0.224 (2σ). Such a large response to the tidal field requires that Titan’s interior be deformable over time scales of the orbital period, in a way that is consistent with a global ocean at depth.

  16. Crystalline titanate catalyst supports

    DOEpatents

    Anthony, Rayford G.; Dosch, Robert G.

    1993-01-01

    A series of new crystalline titanates (CT) are shown to have considerable potential as catalyst supports. For Pd supported catalyst, the catalytic activity for pyrene hydrogenation was substantially different depending on the type of CT, and one was substantially more active than Pd on hydrous titanium oxide (HTO). For 1-hexene hydrogenation the activities of the new CTs were approximately the same as for the hydrous metal oxide supports.

  17. Crystalline titanate catalyst supports

    DOEpatents

    Anthony, R.G.; Dosch, R.G.

    1993-01-05

    A series of new crystalline titanates (CT) are shown to have considerable potential as catalyst supports. For Pd supported catalyst, the catalytic activity for pyrene hydrogenation was substantially different depending on the type of CT, and one was substantially more active than Pd on hydrous titanium oxide (HTO). For 1-hexene hydrogenation the activities of the new CTs were approximately the same as for the hydrous metal oxide supports.

  18. Changes on Titan's surface

    NASA Astrophysics Data System (ADS)

    Solomonidou, A.; Lopes, R. M. C.; Coustenis, A.; Malaska, M. J.; Sotin, C.; Rodriguez, S.; Janssen, M. A.; Drossart, P.; Lawrence, K. J.; Matsoukas, C. K.; Hirtzig, M.; Le Mouelic, S.; Jaumann, R.; Brown, R. H.; Bratsolis, E.

    2015-12-01

    Cassini's Visual and Infrared Mapping Spectrometer (VIMS) and the Titan Radar Mapper have investigated Titan's surface since 2004, unveiling a complex, dynamic and Earth-like surface. Understanding the distribution and interplay of geologic processes is important for constraining models of its interior, surface-atmospheric interactions, and climate evolution. We focus on understanding the origin of the major geomorphological units identified by Lopes et al. (2010, 2015) [1,2], Malaska et al. (2015) [3] and regions we studied in Solomonidou et al. (2014; 2015) [4,5]. Here, we investigate the nature of: Undifferentiated Plains, Hummocky/Mountainous terrains, candidate cryovolcanic sites, Labyrinth, and Dunes in terms of surface albedo behavior and spectral evolution with time to identify possible changes. Using a radiative transfer code, we find that temporal variations of surface albedo occur for some areas. Tui Regio and Sotra Patera, both candidate cryovolcanic regions, change with time, becoming darker and brighter respectively in surface albedo. In contrast, we find that the Undifferentiated Plains and the suggested evaporitic areas [6] in the equatorial regions do not present any significant changes. We are able to report the differences and similarities among the various regions and provide constraints on their chemical composition and specific processes of origin. Our results support the hypothesis that both endogenic and exogenic processes have played important roles in shaping Titan's geologic evolution. Such a variety of geologic processes and their relationship to the methane cycle make Titan important for astrobiology and habitability studies and particularly significant in solar system studies. [1] Lopes, R.M.C., et al.: Icarus, 205, 540-588, 2010; [2] Lopes, R.M.C., et al.: JGR, 118, 416-435, 2013; [3] Malaska, M., et al : Icarus, submitted, 2015;[4] Solomonidou et al.: JGR, 119, 1729-1747, 2014; [5] Solomonidou, A., et al.: In press, 2015; [6] Barnes

  19. Organic chemistry on Titan

    NASA Technical Reports Server (NTRS)

    Chang, S.; Scattergood, T.; Aronowitz, S.; Flores, J.

    1978-01-01

    Observations of nonequilibrium phenomena on the Saturn satellite Titan indicate the occurrence of organic chemical evolution. Greenhouse and thermal inversion models of Titan's atmosphere provide environmental constraints within which various pathways for organic chemical synthesis are assessed. Experimental results and theoretical modeling studies suggest that the organic chemistry of the satellite may be dominated by two atmospheric processes: energetic-particle bombardment and photochemistry. Reactions initiated in various levels of the atmosphere by cosmic ray, Saturn wind, and solar wind particle bombardment of a CH4 - N2 atmospheric mixture can account for the C2-hydrocarbons, the UV-visible-absorbing stratospheric haze, and the reddish color of the satellite. Photochemical reactions of CH4 can also account for the presence of C2-hydrocarbons. In the lower Titan atmosphere, photochemical processes will be important if surface temperatures are sufficiently high for gaseous NH3 to exist. Hot H-atom reactions initiated by photo-dissociation of NH3 can couple the chemical reactions of NH3 and CH4 and produce organic matter.

  20. Landscape Evolution of Titan

    NASA Technical Reports Server (NTRS)

    Moore, Jeffrey

    2012-01-01

    Titan may have acquired its massive atmosphere relatively recently in solar system history. The warming sun may have been key to generating Titan's atmosphere over time, starting from a thin atmosphere with condensed surface volatiles like Triton, with increased luminosity releasing methane, and then large amounts of nitrogen (perhaps suddenly), into the atmosphere. This thick atmosphere, initially with much more methane than at present, resulted in global fluvial erosion that has over time retreated towards the poles with the removal of methane from the atmosphere. Basement rock, as manifested by bright, rough, ridges, scarps, crenulated blocks, or aligned massifs, mostly appears within 30 degrees of the equator. This landscape was intensely eroded by fluvial processes as evidenced by numerous valley systems, fan-like depositional features and regularly-spaced ridges (crenulated terrain). Much of this bedrock landscape, however, is mantled by dunes, suggesting that fluvial erosion no longer dominates in equatorial regions. High midlatitude regions on Titan exhibit dissected sedimentary plains at a number of localities, suggesting deposition (perhaps by sediment eroded from equatorial regions) followed by erosion. The polar regions are mainly dominated by deposits of fluvial and lacustrine sediment. Fluvial processes are active in polar areas as evidenced by alkane lakes and occasional cloud cover.

  1. AVIATR - Aerial Vehicle for In-situ and Airborne Titan Reconnaissance A Titan Airplane Mission Concept

    NASA Technical Reports Server (NTRS)

    Barnes, Jason W.; Lemke, Lawrence; Foch, Rick; McKay, Christopher P.; Beyer, Ross A.; Radebaugh, Jani; Atkinson, David H.; Lorenz, Ralph D.; LeMouelic, Stephane; Rodriguez, Sebastien; Gundlach, Jay; Giannini, Francesco; Bain, Sean; Flasar, F. Michael; Hurford, Terry; Anderson, Carrie M.; Merrison, Jon; Adamkovics, Mate; Kattenhorn, Simon A.; Mitchell, Jonathan; Burr, Devon M.; Colaprete, Anthony; Schaller, Emily; Friedson, A. James; Edgett, Kenneth S.; Coradini, Angioletta; Adriani, Alberto; Sayanagi, Kunio M.; Malaska, Michael J.; Morabito, David; Reh, Kim

    2011-01-01

    We describe a mission concept for a stand-alone Titan airplane mission: Aerial Vehicle for In-situ and Airborne Titan Reconnaissance (AVIATR). With independent delivery and direct-to-Earth communications, AVIATR could contribute to Titan science either alone or as part of a sustained Titan Exploration Program. As a focused mission, AVIATR as we have envisioned it would concentrate on the science that an airplane can do best: exploration of Titan's global diversity. We focus on surface geology/hydrology and lower-atmospheric structure and dynamics. With a carefully chosen set of seven instruments-2 near-IR cameras, 1 near-IR spectrometer, a RADAR altimeter, an atmospheric structure suite, a haze sensor, and a raindrop detector-AVIATR could accomplish a significant subset of the scientific objectives of the aerial element of flagship studies. The AVIATR spacecraft stack is composed of a Space Vehicle (SV) for cruise, an Entry Vehicle (EV) for entry and descent, and the Air Vehicle (AV) to fly in Titan's atmosphere. Using an Earth-Jupiter gravity assist trajectory delivers the spacecraft to Titan in 7.5 years, after which the AVIATR AV would operate for a 1-Earth-year nominal mission. We propose a novel 'gravity battery' climb-then-glide strategy to store energy for optimal use during telecommunications sessions. We would optimize our science by using the flexibility of the airplane platform, generating context data and stereo pairs by flying and banking the AV instead of using gimbaled cameras. AVIATR would climb up to 14 km altitude and descend down to 3.5 km altitude once per Earth day, allowing for repeated atmospheric structure and wind measurements all over the globe. An initial Team-X run at JPL priced the AVIATR mission at FY10 $715M based on the rules stipulated in the recent Discovery announcement of opportunity. Hence we find that a standalone Titan airplane mission can achieve important science building on Cassini's discoveries and can likely do so within

  2. Progress at the TITAN-EBIT

    SciTech Connect

    Klawitter, R.; Alanssari, M.; Frekers, D.; Chowdhury, U.; Gwinner, G.; Chaudhuri, A.; Grossheim, A.; Kwiatkowski, A. A.; Leach, K.; Schultz, B. E.; Dilling, J.; López-Urrutia, J. R. Crespo; Ettenauer, S.; Gallant, A. T.; Macdonald, T. D.; Lennarz, A.; Simon, M. C.; Seeraji, S.; Andreoiu, C.

    2015-01-09

    Precision mass measurements of short-lived isotopes provide insight into a wide array of physics, including nuclear structure, nucleosynthesis, and tests of the Standard Model. The precision of Penning trap mass spectrometry (PTMS) measurements is limited by the lifetime of the isotopes of interest, but scales proportionally with their charge state q, making highly charged ions attractive for mass measurements of nuclides far from stability. TITAN, TRIUMF's Ion Trap(s) for Atomic and Nuclear science, is currently the only setup in the world coupling an EBIT to a rare isotope facility for the purpose of PTMS. Charge breeding ions for Penning trap mass spectrometry, however, entails specific set of challenges. To make use of its potential, efficiencies have to be high, breeding times have to be short and the ion energy spread has to be small. An overview of the TITAN facility and charge-breeding program is given, current and future developments are highlighted and some selected results are presented.

  3. Greenhouse models of the atmosphere of Titan.

    NASA Technical Reports Server (NTRS)

    Pollack, J. B.

    1973-01-01

    The greenhouse effect is calculated for a series of Titanian atmosphere models with different proportions of methane, hydrogen, helium, and ammonia. A computer program is used in temperature-structure calculations based on radiative-convective thermal transfer considerations. A brightness temperature spectrum is derived for Titan and is compared with available observational data. It is concluded that the greenhouse effect on Titan is generated by pressure-induced transitions of methane and hydrogen. The helium-to-hydrogen ratio is found to have a maximum of about 1.5. The surface pressure is estimated to be at least 0.4 atm, with a daytime temperature of about 155 K at the surface. The presence of methane clouds in the upper troposphere is indicated. The clouds have a significant optical depth in the visible, but not in the thermal, infrared.

  4. Titan after Cassini Huygens

    NASA Astrophysics Data System (ADS)

    Beauchamp, P. M.; Lunine, J.; Lebreton, J.; Coustenis, A.; Matson, D.; Reh, K.; Erd, C.

    2008-12-01

    In 2005, the Huygens Probe gave us a snapshot of a world tantalizingly like our own, yet frozen in its evolution on the threshold of life. The descent under parachute, like that of Huygens in 2005, is happening again, but this time in the Saturn-cast twilight of winter in Titan's northern reaches. With a pop, the parachute is released, and then a muffled splash signals the beginning of the first floating exploration of an extraterrestrial sea-this one not of water but of liquid hydrocarbons. Meanwhile, thousands of miles away, a hot air balloon, a "montgolfiere," cruises 6 miles above sunnier terrain, imaging vistas of dunes, river channels, mountains and valleys carved in water ice, and probing the subsurface for vast quantities of "missing" methane and ethane that might be hidden within a porous icy crust. Balloon and floater return their data to a Titan Orbiter equipped to strip away Titan's mysteries with imaging, radar profiling, and atmospheric sampling, much more powerful and more complete than Cassini was capable of. This spacecraft, preparing to enter a circular orbit around Saturn's cloud-shrouded giant moon, has just completed a series of flybys of Enceladus, a tiny but active world with plumes that blow water and organics from the interior into space. Specialized instruments on the orbiter were able to analyze these plumes directly during the flybys. Titan and Enceladus could hardly seem more different, and yet they are linked by their origin in the Saturn system, by a magnetosphere that sweeps up mass and delivers energy, and by the possibility that one or both worlds harbor life. It is the goal of the NASA/ESA Titan Saturn System Mission (TSSM) to explore and investigate these exotic and inviting worlds, to understand their natures and assess the possibilities of habitability in this system so distant from our home world. Orbiting, landing, and ballooning at Titan represent a new and exciting approach to planetary exploration. The TSSM mission

  5. Titan's Mid-latitude Clouds

    NASA Astrophysics Data System (ADS)

    Roe, Henry G.; Schaller, E. L.; Trujillo, C. A.; Brown, M. E.

    2007-10-01

    In the first few years of spatially resolved observations of Titan's tropospheric methane clouds (2001-2003) all of the clouds were clustered in the south polar region. This time period coincided with the southern summer solstice (October 2002) and these south polar clouds are almost certainly a seasonal phenomenon. Starting in December 2003 we began seeing clouds in a narrow latitude range centered at 40°S latitude. In Roe et al. (2005a) we published this initial discovery and speculated that the clouds might be due either to changes in the seasonal circulation pattern or a process linked to surface geography. Further observations soon revealed that the clouds were significantly clustered over one region of longitude (near 350°W), strongly suggesting a geographically controlled origin (Roe et al. 2005b), although Cassini observations suggest a circulation-induced convergence origin (Griffith et al. 2005). The actual answer is most likely a combination of geographic surface effects with the atmospheric circulation. We report here on our continuing ground-based observation campaign, including observations on 65 nights in the 2006-2007 apparition with the Gemini 8-m telescope. With two more years of observations since the data shown in Roe et al. (2005b) we now have much firmer conclusions with respect to the spatial distribution and temporal characteristics of the mid-latitude clouds. We will present our latest understanding of Titan's mid-latitude clouds given the entire dataset now available to us. References Griffith, C.A., & 26 co-authors 2005. Science, 310, 474. Roe, H.G., A.H. Bouchez, C.A. Trujillo, E.L. Schaller, & M.E. Brown 2005a. ApJL, 618, 49. Roe, H.G., M.E. Brown, E.L. Schaller, A.H. Bouchez, & C.A. Trujillo 2005b. Science, 310, 477. This work is supported by NASA under Grant #NNX07AK74G issued through the Planetary Astronomy Program.

  6. Titan's Methane Cycle is Closed

    NASA Astrophysics Data System (ADS)

    Hofgartner, J. D.; Lunine, J. I.

    2013-12-01

    Doppler tracking of the Cassini spacecraft determined a polar moment of inertia for Titan of 0.34 (Iess et al., 2010, Science, 327, 1367). Assuming hydrostatic equilibrium, one interpretation is that Titan's silicate core is partially hydrated (Castillo-Rogez and Lunine, 2010, Geophys. Res. Lett., 37, L20205). These authors point out that for the core to have avoided complete thermal dehydration to the present day, at least 30% of the potassium content of Titan must have leached into an overlying water ocean by the end of the core overturn. We calculate that for probable ammonia compositions of Titan's ocean (compositions with greater than 1% ammonia by weight), that this amount of potassium leaching is achievable via the substitution of ammonium for potassium during the hydration epoch. Formation of a hydrous core early in Titan's history by serpentinization results in the loss of one hydrogen molecule for every hydrating water molecule. We calculate that complete serpentinization of Titan's core corresponds to the release of more than enough hydrogen to reconstitute all of the methane atoms photolyzed throughout Titan's history. Insertion of molecular hydrogen by double occupancy into crustal clathrates provides a storage medium and an opportunity for ethane to be converted back to methane slowly over time--potentially completing a cycle that extends the lifetime of methane in Titan's surface atmosphere system by factors of several to an order of magnitude over the photochemically-calculated lifetime.

  7. Synthesis of nanosized sodium titanates

    SciTech Connect

    Hobbs, David T.; Taylor-Pashow, Kathryn M. L.; Elvington, Mark C.

    2015-09-29

    Methods directed to the synthesis and peroxide-modification of nanosized monosodium titanate are described. Methods include combination of reactants at a low concentration to a solution including a nonionic surfactant. The nanosized monosodium titanate can exhibit high selectivity for sorbing various metallic ions.

  8. Acetylene on Titan

    NASA Astrophysics Data System (ADS)

    Singh, Sandeep; McCord, Thomas B.; Combe, Jean-Philippe; Rodriguez, Sebastien; Cornet, Thomas; Le Mouélic, Stéphane; Clark, Roger Nelson; Maltagliati, Luca; Chevrier, Vincent

    2016-10-01

    Saturn's moon Titan possesses a thick atmosphere that is mainly composed of N2 (98%), CH4 (2 % overall, but 4.9% close to the surface) and less than 1% of minor species, mostly hydrocarbons [1]. A dissociation of N2 and CH4 forms complex hydrocarbons in the atmsophere and acetylene (C2H2) and ethane (C2H6) are produced most abundently. Since years, C2H2 has been speculated to exist on the surface of Titan based on its high production rate in the stratosphere predicted by photochemical models [2,3] and from its detection as trace gas sublimated/evaporated from the surface after the landing of the Huygens probe by the Gas Chromatograph Mass Spectrometer (GCMS) [1]. Here we show evidence of acetylene (C2H2) on the surface of Titan by detecting absorption bands at 1.55 µm and 4.93 µm using Cassini Visual and Infrared Mapping Spectrometer (VIMS) [4] at equatorial areas of eastern Shangri-La, and Fensal-Aztlan/Quivira.An anti-correlation of absorption band strength with albedo indicates greater concentrations of C2H2 in the dark terrains, such as sand dunes and near the Huygens landing site. The specific location of the C2H2 detections suggests that C2H2 is mobilized by surface processes, such as surface weathering by liquids through dissolution/evaporation processes.References:[1]Niemann et al., Nature 438, 779–784 (2005).[2]Lavvas et al., Planetary and Space Science 56, 67 – 99 (2008).[3]Lavvas et al., Planetary and Space Science 56, 27 – 66 (2008).[4] Brown et al., The Cassini-Huygens Mission 111–168 (Springer, 2004).

  9. Titan impacts and escape

    NASA Astrophysics Data System (ADS)

    Korycansky, D. G.; Zahnle, Kevin J.

    2011-01-01

    We report on hydrodynamic calculations of impacts of large (multi-kilometer) objects on Saturn's moon Titan. We assess escape from Titan, and evaluate the hypothesis that escaping ejecta blackened the leading hemisphere of Iapetus and peppered the surface of Hyperion. We carried out two- and three-dimensional simulations of impactors ranging in size from 4 to 100 km diameter, impact velocities between 7 and 15 km s -1, and impact angles from 0° to 75° from the vertical. We used the ZEUSMP2 hydrocode for the calculations. Simulations were made using three different geometries: three-dimensional Cartesian, two-dimensional axisymmetric spherical polar, and two-dimensional plane polar. Three-dimensional Cartesian geometry calculations were carried out over a limited domain (e.g. 240 km on a side for an impactor of size di = 10 km), and the results compared to ones with the same parameters done by Artemieva and Lunine (2005); in general the comparison was good. Being computationally less demanding, two-dimensional calculations were possible for much larger domains, covering global regions of the satellite (from 800 km below Titan's surface to the exobase altitude 1700 km above the surface). Axisymmetric spherical polar calculations were carried out for vertical impacts. Two-dimensional plane-polar geometry calculations were made for both vertical and oblique impacts. In general, calculations among all three geometries gave consistent results. Our basic result is that the amount of escaping material is less than or approximately equal to the impactor mass even for the most favorable cases. Amounts of escaping material scaled most strongly as a function of velocity, with high-velocity impacts generating the largest amount, as expected. Dependence of the relative amount of escaping mass fesc = mesc/ Mi on impactor diameter di was weak. Oblique impacts (impact angle θi > 45°) were more effective than vertical or near-vertical impacts; ratios of mesc/ Mi ˜ 1-2 were

  10. Zinc titanate sorbents

    DOEpatents

    Gupta, Raghubir P.; Gangwal, Santosh K.; Jain, Suresh C.

    1998-01-01

    The present invention provides a zinc titanate sorbent material useful in desulfurization applications. The zinc titanate material is in the form of generally spherical particles of substantially uniform chemical distribution. The sorbent material is capable of absorbing sulfur compounds from a gaseous feed in an amount of at least about 15 weight percent based on the weight of the sorbent. The sorbent material is prepared by a process including: (a) forming a zinc oxide/titanium dioxide dry blend, (b) preparing a substantially uniform aqueous slurry comprising the zinc oxide/titanium dioxide dry blend, organic binder, and at least about 1 weight percent inorganic binder based on the solids weight of the slurry, (c) spray drying the slurry to produce substantially spherical particles, and (d) calcining the particles at a temperature of between about 750.degree. C. to about 950.degree. C. The dry blend is formed by mixing between about 0.5 to about 2 parts zinc oxide having a median particle size of less than about 0.5 .mu., and about 1 part titanium dioxide having a median particle size of less than about 1 .mu.. The slurry contains substantially no free silica and may be prepared by the process including (1) preparing an aqueous solution of organic binder, (2) adding the dry blend to the aqueous solution of organic binder, and (3) adding the inorganic binder to the solution of organic binder, and blend. Additional reagents, such as a surfactant, may also be incorporated into the sorbent material. The present invention also provides a process for desulfurizing a gaseous stream. The process includes passing a gaseous stream through a reactor containing an attrition resistant zinc titanate sorbent material of the present invention.

  11. Zinc titanate sorbents

    DOEpatents

    Gupta, R.P.; Gangwal, S.K.; Jain, S.C.

    1998-02-03

    The present invention provides a zinc titanate sorbent material useful in desulfurization applications. The zinc titanate material is in the form of generally spherical particles of substantially uniform chemical distribution. The sorbent material is capable of absorbing sulfur compounds from a gaseous feed in an amount of at least about 15 weight percent based on the weight of the sorbent. The sorbent material is prepared by a process including: (a) forming a zinc oxide/titanium dioxide dry blend, (b) preparing a substantially uniform aqueous slurry comprising the zinc oxide/titanium dioxide dry blend, organic binder, and at least about 1 weight percent inorganic binder based on the solids weight of the slurry, (c) spray drying the slurry to produce substantially spherical particles, and (d) calcining the particles at a temperature of between about 750 to about 950 C. The dry blend is formed by mixing between about 0.5 to about 2 parts zinc oxide having a median particle size of less than about 0.5 microns, and about 1 part titanium dioxide having a median particle size of less than about 1 micron. The slurry contains substantially no free silica and may be prepared by the process including (1) preparing an aqueous solution of organic binder, (2) adding the dry blend to the aqueous solution of organic binder, and (3) adding the inorganic binder to the solution of organic binder, and blend. Additional reagents, such as a surfactant, may also be incorporated into the sorbent material. The present invention also provides a process for desulfurizing a gaseous stream. The process includes passing a gaseous stream through a reactor containing an attrition resistant zinc titanate sorbent material of the present invention.

  12. The Tides of Titan

    NASA Astrophysics Data System (ADS)

    Iess, L.; Jacobson, R.; Ducci, M.; Stevenson, D. J.; Lunine, J. I.; Armstrong, J. W.; Asmar, S.; Racioppa, P.; Rappaport, N. J.; Tortora, P.

    2012-12-01

    Titan has long been thought to host a subsurface water ocean. A liquid water or water-ammonia layer underneath the outer icy shell was invoked to explain the Voyager and Cassini observations of abundant methane (an easily dissociated species) in the atmosphere of the satellite. Given the paucity of surface hydrocarbon reservoirs, the atmospheric methane must be supplied by the interior, and an ocean can both provide a large storage volume and facilitate the outgassing from the deeper layers of the satellite to the surface. Huygens probe observations of a Schumann-like resonance point to the presence of an electrically conductive layer at a depth of 50-100 km, which has been interpreted to be the top of an ammonia-doped ocean [1]. Cassini gravity observations provide stronger evidence of the existence of such subsurface ocean. By combining precise measurements of the spacecraft range rate during six flybys, suitably distributed along Titan's orbit (three near pericenter, two near apocenter one near quadrature), we have been able to determine the k2 Love number to be k2 = 0.589±0.150 and k2 = 0.637±0.224 in two independent so-lutions (quoted uncertainties are 2-sigma) [2]. Such a large value indicates that Titan is highly deformable over time scales of days, as one would expect if a global ocean were hidden beneath the outer icy shell. The inclusion of time-variable gravity in the solution provided also a more reliable estimate of the static field, including an updated long-wavelength geoid. We discuss the methods adopted in our solutions and some implications of our results for the interior structure of Titan, and outline the expected improvements from the additional gravity flybys before the end of mission in 2017. [1] C. Beghin, C. Sotin, M. Hamelin, Comptes Rendue Geoscience, 342, 425 (2010). [2] L. Iess, R.A. Jacobson, M. Ducci, D.J. Stevenson, J.I. Lunine, J.W. Armstrong, S.W. Asmar, P. Racioppa, N.J. Rappaport, P. Tortora, Science, 337, 457 (2012).

  13. Titan Science Return Quantification

    NASA Technical Reports Server (NTRS)

    Weisbin, Charles R.; Lincoln, William

    2014-01-01

    Each proposal for a NASA mission concept includes a Science Traceability Matrix (STM), intended to show that what is being proposed would contribute to satisfying one or more of the agency's top-level science goals. But the information traditionally provided cannot be used directly to quantitatively compare anticipated science return. We added numerical elements to NASA's STM and developed a software tool to process the data. We then applied this methodology to evaluate a group of competing concepts for a proposed mission to Saturn's moon, Titan.

  14. Using Titanic to Teach Earth Science

    NASA Astrophysics Data System (ADS)

    Sumners, C.; Ledley, T. S.; Reiff, P. H.

    2002-05-01

    The Houston Museum of Natural Science is producing a unique planetarium documentary called Night of the Titanic. The program uses full-dome simulations to recreate the environment in the North Atlantic off the Newfoundland Coast on April 14, 1912 and to show the complex series of natural and human events that sank the ``unsinkable'' ship. Night of the Titanic is a collaboration between the Museum, TERC, and Rice University to solve lingering mysteries that still surround this great tragedy. The collaborative research has produced discoveries and interpretations than have never been presented and rendered as simulations before, and teaches Earth science in a new and dramatic way. All eyewitness reports have been considered in the context of physical evidence. For instance, the Titanic now lies on a gentle slope 12,460 feet below the surface of the cold North Atlantic with its bow virtually intact and stern, a mangled heap of metal, 2,000 feet behind. There can be no doubt that the ship broke up near the surface before sinking. Several passengers in life boats described this fracture in detail. Yet ship officers claimed that the ship sank in one piece to protect the reputation of the White Star Line. ``Night of the Titanic'' will be our third digital dome Earth science show. We created the world's first Earth science ultrawidescreen digital production, ``Powers of Time'', which was released January 2000. The world's first fulldome digital Earth science production was ``Force 5'', on hurricanes, tornadoes, and space storms, which has been showing in Pittsburgh and Houston since early 2001.

  15. Titan Explorer Entry, Descent and Landing Trajectory Design

    NASA Technical Reports Server (NTRS)

    Fisher, Jody L.; Lindberg, Robert E.; Lockwood, Mary Kae

    2006-01-01

    The Titan Explorer mission concept includes an orbiter, entry probe and inflatable airship designed to take remote and in-situ measurements of Titan's atmosphere. A modified entry, descent and landing trajectory at Titan that incorporates mid-air airship inflation (under a parachute) and separation is developed and examined for Titan Explorer. The feasibility of mid-air inflation and deployment of an airship under a parachute is determined by implementing and validating an airship buoyancy and inflation model in the trajectory simulation program, Program to Optimize Simulated Trajectories II (POST2). A nominal POST2 trajectory simulation case study is generated which examines different descent scenarios by varying airship inflation duration, orientation, and separation. The buoyancy model incorporation into POST2 is new to the software and may be used in future trajectory simulations. Each case from the nominal POST2 trajectory case study simulates a successful separation between the parachute and airship systems with sufficient velocity change as to alter their paths to avoid collision throughout their descent. The airship and heatshield also separate acceptably with a minimum distance of separation from the parachute system of 1.5 km. This analysis shows the feasibility of airship inflation on a parachute for different orientations, airship separation at various inflation times, and preparation for level-flight at Titan.

  16. Titan's astrobiology: some new data

    NASA Astrophysics Data System (ADS)

    Raulin, Francois; Coll, Patrice; Buch, Arnaud; Cloix, Megane; Guan, Yuan Yong; Jerome, Murielle; Poch, Olivier; Ramirez, Sandra I.; Szopa, Cyril; Cottin, Hervé

    The Cassini-Huygens observations of Titan have strongly strengthened its astrobiological impor-tance, clearly showing that Titan is one of the key planetary bodies for astrobiological studies. Indeed the Cassini-Huygens data show that there are many similarities which can be found when comparing Titan and the early Earth, in spite of much lower temperatures for Titan. One of these similarities is the presence of an active and complex organic chemistry in Titan's environment, which occurs from the high atmosphere to the surface and very likely in the sub-surface. This organic chemistry involves several of the key compounds of terrestrial prebiotic chemistry, and it represents, by itself, a major astrobiological aspect of Titan. Moreover, the potential presence of an internal water-ocean makes Titan a potential habitable environment, of obvious astrobiological importance. In fact, after five years of close observation by remote sensing and in situ instrumentations from the Cassini-Huygens mission, Titan does not look any more like a frozen primitive Earth, but it looks like an evolving planet, geologically active, with cryo-volcanism, eolian erosion, clouds and precipitations, and a methane cycle analogous to the water cycle on Earth. But the new data also show that a complex organic chemistry is taking place in the very high atmospheric layers of the satellite, with the formation in the ionosphere of high molecular weight (up about 10 000 Daltons) ions. Are these ions abundant enough in the lower atmosphere zones to act as organic monomers which then grow by aggregation, sedimentation and condensation down to the surface? This is one of the key questions that chemical models have now to answer. Cassini-Huygens observations have shown that there is no large surface ocean on Titan, but large regional lakes which behave like evolving liquid media. Those lakes are probably accumulating complex organics of astrobiological interest, including organic aerosols, and could

  17. Titan's Emergence from Winter

    NASA Technical Reports Server (NTRS)

    Flasar, F. Michael; Achterberg, Richard; Jennings, Donald; Schinder, Paul

    2011-01-01

    We summarize the changes in Titans thermal structure derived from Cassini CIRS and radio-occultation data during the transition from winter to early spring. Titan's surface, and middle atmosphere show noticeable seasonal change, whereas that in most of the troposphere is mated. This can be understood in terms of the relatively small radiative relaxation time in the middle atmosphere and much larger time scale in the troposphere. The surface exhibits seasonal change because the heat capacity in an annual skin depth is much smaller than that in the lowest scale height of the troposphere. Surface temperatures rise 1 K at raid and high latitudes in the winter northern hemisphere and cool in the southern hemisphere. Changes in in the middle atmosphere are more complicated. Temperatures in the middle stratosphere (approximately 1 mbar) increase by a few kelvin at mid northern latitudes, but those at high latitudes first increase as that region moves out of winter shadow, and then decrease. This probably results from the combined effect of increased solar heating as the suit moves higher in the sky and the decreased adiabatic warming as the sinking motions associated with the cross-equatorial meridional cell weaken. Consistent with this interpretation, the warm temperatures observed higher up at the winter polar stratopause cool significantly.

  18. Monosodium Titanate Sludge Filtration

    SciTech Connect

    Dworjanyn, L.O.

    2000-11-07

    Good filterability of tetraphenylborate (TPB) slurry is attributed to the hydrophobic nature of crystalline organic TPB that forms a firm but porous filter cake, allowing salt solution to pass through without unduly compressing the cake. Addition of inorganic sludge or monosodium titanate (MST) has an adverse effect on filtration, but the overall filtration rate with TPB is satisfactory. Poor cross-flow filtration performance for the Salt Disposition Alternatives requiring MST filtration is attributed primarily to the difficulty in filtering the residual inorganic sludge rich in iron and aluminum precipitates. Ferric hydrolysis products and colloids form a bulky and sticky filter cake significantly reducing filtration rate. Similarly poor filtration rates were observed in the BNFL ferric/ferrous precipitation process, necessitating a change to permanganate precipitation. This report, based on a few sludge settling observations, does not resolve the MST/Sludge filterability issue. However, it does identify the need for a change in emphasis from cross-flow optimization to understanding and controlling the chemistry and physics of alkaline inorganic particle suspensions and filterability. Promising potential exists to identify or develop surfactants or flocculants to enhance filterability of SRS sludge and monosodium titanate. Additional work is needed to provide a basic understanding of the nature of caustic sludge filter cake formation.

  19. Heavy Ion Formation in Titan's Ionosphere: Magnetospheric Introduction of Free Oxygen and a Source of Titan's Aerosols?

    NASA Technical Reports Server (NTRS)

    Sittler, E. C., Jr.; Ali, A.; Cooper, J. F.; Hartle, R. E.; Johnson, R. E.; Coates, A. J.; Young, D. T.

    2009-01-01

    Discovery by Cassini's plasma instrument of heavy positive and negative ions within Titan's upper atmosphere and ionosphere has advanced our understanding of ion neutral chemistry within Titan's upper atmosphere, primarily composed of molecular nitrogen, with approx.2.5% methane. The external energy flux transforms Titan's upper atmosphere and ionosphere into a medium rich in complex hydrocarbons, nitriles and haze particles extending from the surface to 1200 km altitudes. The energy sources are solar UV, solar X-rays, Saturn's magnetospheric ions and electrons, solar wind and shocked magnetosheath ions and electrons, galactic cosmic rays (CCR) and the ablation of incident meteoritic dust from Enceladus' E-ring and interplanetary medium. Here it is proposed that the heavy atmospheric ions detected in situ by Cassini for heights >950 km, are the likely seed particles for aerosols detected by the Huygens probe for altitudes <100km. These seed particles may be in the form of polycyclic aromatic hydrocarbons (PAH) containing both carbon and hydrogen atoms CnHx. There could also be hollow shells of carbon atoms, such as C60, called fullerenes which contain no hydrogen. The fullerenes may compose a significant fraction of the seed particles with PAHs contributing the rest. As shown by Cassini, the upper atmosphere is bombarded by magnetospheric plasma composed of protons, H(2+) and water group ions. The latter provide keV oxygen, hydroxyl and water ions to Titan's upper atmosphere and can become trapped within the fullerene molecules and ions. Pickup keV N(2+), N(+) and CH(4+) can also be implanted inside of fullerenes. Attachment of oxygen ions to PAH molecules is uncertain, but following thermalization O(+) can interact with abundant CH4 contributing to the CO and CO2 observed in Titan's atmosphere. If an exogenic keV O(+) ion is implanted into the haze particles, it could become free oxygen within those aerosols that eventually fall onto Titan's surface. The process

  20. Mapping products of Titan's surface

    USGS Publications Warehouse

    Stephan, Katrin; Jaumann, Ralf; Karkoschka, Erich; Barnes, Jason W.; Tomasko, Martin G.; Turtle, Elizabeth P.; Le Corre, Lucille; Langhans, Mirjam; Le Mouelic, Stephane; Lorenz, Ralf D.; Perry, Jason; Brown, Robert H.; Lebreton, Jean-Pierre

    2009-01-01

    Remote sensing instruments aboard the Cassini spacecraft have been observed the surface of Titan globally in the infrared and radar wavelength ranges as well as locally by the Huygens instruments revealing a wealth of new morphological features indicating a geologically active surface. We present a summary of mapping products of Titan's surface derived from data of the remote sensing instruments onboard the Cassini spacecraft (ISS, VIMS, RADAR) as well as the Huygens probe (DISR) that were achieved during the nominal Cassini mission including an overview of Titan's recent nomenclature.

  1. Mapping Methane in Titan's Atmosphere near Titan's Surface

    NASA Astrophysics Data System (ADS)

    Young, Eliot; Soderblom, Jason; Barnes, Jason

    2016-06-01

    Titan's atmospheric methane may be coupled to sources and sinks on its surface. In order to map methane concentrations in layers just above Titan's surface, we use data sets in which locations on Titan are imaged from a variety of viewing angles (and within a short time span). We also use a radiative transfer code based on the Markov Chain method of Esposito and House (1978, AJ 219, 1058) to accommodate spherical atmospheric geometries. We report on (a) selected Cassini/VIMS flybys that image terrain on Titan from different angles, (b) the expected vertical resolution of methane maps near the surface from these flybys and (c) preliminary results: 3D methane and haze distributions and surface albedos.

  2. Ices in Titan's Lower Stratosphere

    NASA Technical Reports Server (NTRS)

    Anderson, Carrie

    2010-01-01

    Analyses of Cassini CIRS far-infrared limb spectra of Titan at 15N, 15S, and 58S reveal a broad emission feature between 70 and 270/cm, restricted to altitudes between 60 and 100 km. This emission feature is chemically different from Titan's photochemical aerosol, which has an emission feature peak around 145 cm-1. The shape of the observed broad emission feature resembles a mixture of the solid component of the two most abundant nitrites in Titan's stratosphere, that of HCN and HC3N. Following the saturation vapor pressure vertical profiles of HCN and HC3N, the 60 to 100 km altitude range corresponds closely to the vertical location where these nitriles are expected to condense out and form small, suspended ice particles. This is the first time ices in Titan's stratosphere have been identified at latitudes south of 50N. Results and physical implications will be discussed.

  3. Titan's greenhouse and antigreenhouse effects

    NASA Technical Reports Server (NTRS)

    Mckay, Christopher P.; Pollack, James B.; Courtin, Regis

    1992-01-01

    Thermal mechanisms active in Titan's atmosphere are discussed in a brief review of data obtained during the Voyager I flyby in 1980. Particular attention is given to the greenhouse effect (GHE) produced by atmospheric H2, N2, and CH4; this GHE is stronger than that on earth, with CH4 and H2 playing roles similar to those of H2O and CO2 on earth. Also active on Titan is an antigreenhouse effect, in which dark-brown and orange organic aerosols block incoming solar light while allowing IR radiation from the Titan surface to escape. The combination of GHE and anti-GHE leads to a surface temperature about 12 C higher than it would be if Titan had no atmosphere.

  4. Seasonal Changes in Titan's Meteorology

    NASA Technical Reports Server (NTRS)

    Turtle, E. P.; DelGenio, A. D.; Barbara, J. M.; Perry, J. E.; Schaller, E. L.; McEwen, A. S.; West, R. A.; Ray, T. L.

    2011-01-01

    The Cassini Imaging Science Subsystem has observed Titan for 1/4 Titan year, and we report here the first evidence of seasonal shifts in preferred locations of tropospheric methane clouds. South \\polar convective cloud activity, common in late southern summer, has become rare. North \\polar and northern mid \\latitude clouds appeared during the approach to the northern spring equinox in August 2009. Recent observations have shown extensive cloud systems at low latitudes. In contrast, southern mid \\latitude and subtropical clouds have appeared sporadically throughout the mission, exhibiting little seasonality to date. These differences in behavior suggest that Titan s clouds, and thus its general circulation, are influenced by both the rapid temperature response of a low \\thermal \\inertia surface and the much longer radiative timescale of Titan s cold thick troposphere. North \\polar clouds are often seen near lakes and seas, suggesting that local increases in methane concentration and/or lifting generated by surface roughness gradients may promote cloud formation. Citation

  5. A Photochemically-Based Microphysical Study of Titan Hazes

    NASA Astrophysics Data System (ADS)

    Wilson, E. H.; West, R. A.; Edgington, S. G.; Atreya, S. K.

    2003-05-01

    Titan's haze region acts as an end product of Titan's hydrocarbon and nitrile chemistry and plays an important role in the distribution of atmospheric constituents, affecting the transfer of radiation that helps trigger that chemistry. Recent investigations into the chemical sources of Titan haze [1,2] have suggested that the source region of Titan haze might be lower than what is found in most conventional microphysical models. Furthermore, modeling [1] and laboratory studies [3] have shown that PAHs may be more prominent in Titan haze than previously thought. To analyze the implications of these results we use a microphysical model [4] to calculate a haze distribution of spherical particles based on a photochemical source profile. Results will be compared to observations and the possible consequences of fractal haze particles will be discussed. The effects of haze composition on the distribution of hazes as well as on the radiative transfer and resultant chemistry will be examined and placed in the context of the upcoming Cassini-Huygens mission. This research is supported by the National Research Council Research Associateship Program. [1] E. H. Wilson and S. K. Atreya, Planet. Space Sci., in press. [2] S. Lebonnois et al., Icarus, 159, 505-517, 2002. [3] B. N. Khare et al., Icarus, 160, 172-182, 2002. [4] O. B. Toon et al., J. Atmos. Sci., 45, 2123-2143, 1988.

  6. Life on Titan

    NASA Astrophysics Data System (ADS)

    Potashko, Oleksandr

    Volcanoes engender life on heavenly bodies; they are pacemakers of life. All planets during their period of formation pass through volcanism hence - all planets and their satellites pass through the life. Tracks of life If we want to find tracks of life - most promising places are places with volcanic activity, current or past. In the case of just-in-time volcanic activity we have 100% probability to find a life. Therefore the most perspective “search for life” are Enceladus, Io and comets, further would be Venus, Jupiter’s satellites, Saturn’s satellites and first of all - Titan. Titan has atmosphere. It might be result of high volcanic activity - from one side, from other side atmosphere is a necessary condition development life from procaryota to eucaryota. Existence of a planet means that all its elements after hydrogen formed just there inside a planet. The forming of the elements leads to the formation of mineral and organic substances and further to the organic life. Development of the life depends upon many factors, e.g. the distance from star/s. The intensity of the processes of the element formation is inversely to the distance from the star. Therefore we may suppose that the intensity of the life in Mercury was very high. Hence we may detect tracks of life in Mercury, particularly near volcanoes. The distance from the star is only one parameter and now Titan looks very active - mainly due to interior reason. Its atmosphere compounds are analogous to comet tail compounds. Their collation may lead to interesting result as progress occurs at one of them. Volcanic activity is as a source of life origin as well a reason for a death of life. It depends upon the thickness of planet crust. In the case of small thickness of a crust the probability is high that volcanoes may destroy a life on a planet - like Noachian deluge. Destroying of the life under volcano influences doesn’t lead to full dead. As result we would have periodic Noachian deluge or

  7. The TITAN magnet configuration

    NASA Astrophysics Data System (ADS)

    Bathke, C. G.

    The TITAN study uses copper-alloy ohmic-heating coils (OHC) to start up inductively a reversed-field-pinch (RFP) fusion reactor. The plasma equilibrium is maintained with a pair of superconducting equilibrium-field coils (EFCs). A second pair of copper EFCs provides the necessary trimming of the equilibrium field during plasma transients. A compact toroidal-field-coil (TFC) set is provided by an integrated blanket/coil (IBC). The IBC concept also is applied to the toroidal-field divertor coils. Steady-state operation is achieved with oscillating-field current drive, which oscillates at low amplitude and frequency the OHCs, EFCs, the TFCs, and divertor coils about their steady-state currents. An integrated magnet design, which uses low-field, low technology coils, and the related design basis is given.

  8. Titan's rotation - Surface feature observed

    NASA Astrophysics Data System (ADS)

    Lemmon, M. T.; Karkoschka, E.; Tomasko, M.

    1993-06-01

    A surface feature or a near-surface fracture is suggested to account for the time variations in the 0.94, 1.08, and 1.28 micron atmospheric windows of Titan's geometric albedo, relative to its albedo in adjacent methane bands. These observations are noted to be consistent with synchronous rotation. They can also be explained by a 0.1-higher surface albedo on Titan's leading hemisphere.

  9. Simulations of Titan's paleoclimate

    NASA Astrophysics Data System (ADS)

    Lora, Juan M.; Lunine, Jonathan I.; Russell, Joellen L.; Hayes, Alexander G.

    2014-11-01

    We investigate the effects of varying Saturn's orbit on the atmospheric circulation and surface methane distribution of Titan. Using a new general circulation model of Titan's atmosphere, we simulate its climate under four characteristic configurations of orbital parameters that correspond to snapshots over the past 42 kyr, capturing the amplitude range of long-period cyclic variations in eccentricity and longitude of perihelion. The model, which covers pressures from the surface to 0.5 mbar, reproduces the present-day temperature profile and tropospheric superrotation. In all four simulations, the atmosphere efficiently transports methane poleward, drying out the low- and mid-latitudes, indicating that these regions have been desert-like for at least tens of thousands of years. Though circulation patterns are not significantly different, the amount of surface methane that builds up over either pole strongly depends on the insolation distribution; in the present-day, methane builds up preferentially in the north, in agreement with observations, where summer is milder but longer. The same is true, to a lesser extent, for the configuration 14 kyr ago, while the south pole gains more methane in the case for 28 kyr ago, and the system is almost symmetric 42 kyr ago. This confirms the hypothesis that orbital forcing influences the distribution of surface liquids, and that the current observed asymmetry could have been partially or fully reversed in the past. The evolution of the orbital forcing implies that the surface reservoir is transported on timescales of ∼30 kyr, in which case the asymmetry reverses with a period of ∼125 kyr. Otherwise, the orbital forcing does not produce a net asymmetry over longer timescales, and is not a likely mechanism for generating the observed dichotomy.

  10. From Titan's chemistry and exobiology to Titan's astrobiology

    NASA Astrophysics Data System (ADS)

    Raulin, François

    2015-04-01

    When the IDS proposal « Titan's chemistry and exobiology » was submitted to ESA 25 years ago, in the frame of what will become the Cassini-Huygens mission, Titan was already seen as a quite interesting planetary object in the solar system for Exobiology. Several organic compounds of prebiotic interest were identified in its atmosphere, which was thus was expected to be chemically very active, especially in term of organic processes. Atmospheric aerosols seemed to play a key role in this chemistry. Moreover, the presence of an internal aqueous ocean, compatible with life was suspected. A few years later, when astrobiology was (re)invented, Titan became one of the most interesting planetary target for this new (but very similar to exobiology) field. With the Cassini-Huygens mission, the exo/astrobiological interest of Titan has become more and more important. However, the mission has been providing a vision of Titan quite different from what it was supposed. Its atmospheric organic chemistry is very complex and starts in much higher zones than it was believed before, involving high molecular weight species in the ionosphere. Titan's surface appears to be far from homogeneous: instead of been covered by a global methane-ethane ocean, it is very diversified, with dunes, lakes, bright and dark areas, impact and volcanic craters with potential cryovolcanic activity. These various geological areas are continuously feeded by atmospheric aerosols, which represent an important step in the complexity of Titan's organic chemistry, but probably not the final one. Indeed, after being deposited on the surface, in the potential cryovolvanic zones, these particles may react with water ice and form compounds of exo/astrobiological interest, such as amino acids, purine and pyrimidine bases. Moreover, The Cassini-Huygens data strongly support the potential presence of an internal water ocean, which becomes less and less hypothetical and of great interest for exobiology. These

  11. Cloud formation in Titan's Stratosphere

    NASA Astrophysics Data System (ADS)

    Barth, Erika

    2016-06-01

    In addition to the organic haze particles produced photochemically in Titan's upper atmosphere, a number of trace gases are also created. These hydrocarbon and nitrile species include C2H6, C2H2, C4H10, HCN, HC3N, C2H5CN and many more. While both Voyager and Cassini observations have found evidence for ices (e.g. C4N2, HCN) in the atmosphere above Titan's poles, these species are also likely to condense at other latitudes forming optically thin ice layers in the stratosphere. A series of simulations have been conducted using Titan CARMA, a 1-D microphysics and radiative transfer model, to explore cloud particle formation with ˜20 of Titan's trace hydrocarbon and nitrile gases. These species reach their condensation temperatures between 60 and 110 km. Most condense solely as ices, however, C3H8 will condense first near 70 km as a liquid and then freeze as the droplets descend toward the surface. C3H8 and C2H6 join CH4 as a liquid at Titan's surface. Many ices have long condensation timescales resulting in particle radii ˜1 micron or less. Several (including HCN, C3H8, C2H2) will grow 10-50 times larger. Expected condensation altitudes and particle sizes will be presented, as well as the implications for the optical properties of Titan's stratospheric aerosol particles.

  12. The TITAN reversed-field-pinch fusion reactor study

    SciTech Connect

    Not Available

    1990-01-01

    This report discusses research on the titan-1 fusion power core. The major topics covered are: titan-1 fusion-power-core engineering; titan-1 divertor engineering; titan-1 tritium systems; titan-1 safety design and radioactive-waste disposal; and titan-1 maintenance procedures.

  13. Resin-Impregnated Carbon Ablator: A New Ablative Material for Hyperbolic Entry Speeds

    NASA Technical Reports Server (NTRS)

    Esper, Jaime; Lengowski, Michael

    2012-01-01

    Ablative materials are required to protect a space vehicle from the extreme temperatures encountered during the most demanding (hyperbolic) atmospheric entry velocities, either for probes launched toward other celestial bodies, or coming back to Earth from deep space missions. To that effect, the resin-impregnated carbon ablator (RICA) is a high-temperature carbon/phenolic ablative thermal protection system (TPS) material designed to use modern and commercially viable components in its manufacture. Heritage carbon/phenolic ablators intended for this use rely on materials that are no longer in production (i.e., Galileo, Pioneer Venus); hence the development of alternatives such as RICA is necessary for future NASA planetary entry and Earth re-entry missions. RICA s capabilities were initially measured in air for Earth re-entry applications, where it was exposed to a heat flux of 14 MW/sq m for 22 seconds. Methane tests were also carried out for potential application in Saturn s moon Titan, with a nominal heat flux of 1.4 MW/sq m for up to 478 seconds. Three slightly different material formulations were manufactured and subsequently tested at the Plasma Wind Tunnel of the University of Stuttgart in Germany (PWK1) in the summer and fall of 2010. The TPS integrity was well preserved in most cases, and results show great promise.

  14. Ablation response testing of aerospace power supplies

    NASA Astrophysics Data System (ADS)

    Lutz, S. A.; Chan, C. C.

    1993-01-01

    An experimental program was performed to assess the aerothermal ablation response of aerospace power supplies. Full-scale General Purpose Heat Source (GPHS) test articles, Graphite Impact Shell (GIS) test articles, and Lightweight Radioisotope Heater Unit (LWRHU) test articles were all tested without nuclear fuel in simulated reentry environments at the NASA Ames Research Center. Stagnation heating, stagnation pressure, stagnation surface temperature, stagnation surface recession profile, and weight loss measurements were obtained for diffusion-limited and sublimation ablation conditions. The recession profile and weight loss measurements showed an effect of surface features on the stagnation face. The surface features altered the local heating which in turn affected the local ablation.

  15. Laser ablation of blepharopigmentation

    SciTech Connect

    Tanenbaum, M.; Karas, S.; McCord, C.D. Jr. )

    1988-01-01

    This article discusses laser ablation of blepharopigmentation in four stages: first, experimentally, where pigment vaporization is readily achieved with the argon blue-green laser; second, in the rabbit animal model, where eyelid blepharopigmentation markings are ablated with the laser; third, in human subjects, where the argon blue-green laser is effective in the ablation of implanted eyelid pigment; and fourth, in a case report, where, in a patient with improper pigment placement in the eyelid, the laser is used to safely and effectively ablate the undesired pigment markings. This article describes in detail the new technique of laser ablation of blepharopigmentation. Potential complications associated with the technique are discussed.

  16. Thermal Ablation Modeling for Silicate Materials

    NASA Technical Reports Server (NTRS)

    Chen, Yih-Kanq

    2016-01-01

    A general thermal ablation model for silicates is proposed. The model includes the mass losses through the balance between evaporation and condensation, and through the moving molten layer driven by surface shear force and pressure gradient. This model can be applied in the ablation simulation of the meteoroid and the glassy ablator for spacecraft Thermal Protection Systems. Time-dependent axisymmetric computations are performed by coupling the fluid dynamics code, Data-Parallel Line Relaxation program, with the material response code, Two-dimensional Implicit Thermal Ablation simulation program, to predict the mass lost rates and shape change. The predicted mass loss rates will be compared with available data for model validation, and parametric studies will also be performed for meteoroid earth entry conditions.

  17. Advances in Architectural Elements For Future Missions to Titan

    NASA Astrophysics Data System (ADS)

    Reh, Kim; Coustenis, Athena; Lunine, Jonathan; Matson, Dennis; Lebreton, Jean-Pierre; Vargas, Andre; Beauchamp, Pat; Spilker, Tom; Strange, Nathan; Elliott, John

    2010-05-01

    The future exploration of Titan is of high priority for the solar system exploration community as recommended by the 2003 National Research Council (NRC) Decadal Survey [1] and ESA's Cosmic Vision Program themes. Recent Cassini-Huygens discoveries continue to emphasize that Titan is a complex world with very many Earth-like features. Titan has a dense, nitrogen atmosphere, an active climate and meteorological cycles where conditions are such that the working fluid, methane, plays the role that water does on Earth. Titan's surface, with lakes and seas, broad river valleys, sand dunes and mountains was formed by processes like those that have shaped the Earth. Supporting this panoply of Earth-like processes is an ice crust that floats atop what might be a liquid water ocean. Furthermore, Titan is rich in very many different organic compounds—more so than any place in the solar system, except Earth. The Titan Saturn System Mission (TSSM) concept that followed the 2007 TandEM ESA CV proposal [2] and the 2007 Titan Explorer NASA Flagship study [3], was examined [4,5] and prioritized by NASA and ESA in February 2009 as a mission to follow the Europa Jupiter System Mission. The TSSM study, like others before it, again concluded that an orbiter, a montgolfiere hot-air balloon and a surface package (e.g. lake lander, Geosaucer (instrumented heat shield), …) are very high priority elements for any future mission to Titan. Such missions could be conceived as Flagship/Cosmic Vision L-Class or as individual smaller missions that could possibly fit into NASA New Frontiers or ESA Cosmic Vision M-Class budgets. As a result of a multitude of Titan mission studies, a clear blueprint has been laid out for the work needed to reduce the risks inherent in such missions and the areas where advances would be beneficial for elements critical to future Titan missions have been identified. The purpose of this paper is to provide a brief overview of the flagship mission architecture and

  18. The Surface Composition of Titan

    NASA Astrophysics Data System (ADS)

    Clark, R. N.; Pearson, N.; Brown, R. H.; Cruikshank, D. P.; Barnes, J. W.; Jaumann, R.; Soderblom, L. A.; Griffith, C. A.; Rodriguez, S.; Le Mouelic, S.; Lunine, J.; Sotin, C.; Baines, K. H.; Buratti, B. J.; Nicholson, P. D.; Nelson, R.; Stephan, K.

    2011-12-01

    Determining the surface composition of Titan has been inhibited by the lack of spectral properties of potential compounds. We have measured the 0.35 to 5-micron spectral reflectance of a wide range of compounds that might be relevant to Titan and trends are now coming to light with possible spectral matches for classes of materials. While some compounds have been identified and mapped on Titan's surface, such as liquid ethane + methane lakes and benzene, the compounds responsible for the main spectral properties have remained elusive (Clark et al, JGR 2010). Titan's surface is seen in the near infrared in only a few spectral windows, near 0.94, 1.1, 1.3, 1.6, 2.0, 2.68-2.78, and 4.9-5.1 microns in the Cassini Visual and Infrared Mapping Spectrometer (VIMS) spectral range. At shorter wavelengths, UV absorption in the spectra of Titan's haze constrains the surface composition because haze particles settle onto Titan's surface. The average apparent reflectance in the IR windows generally decreases with increasing wavelength except for the 2.7 and 5-micron windows which are at similar levels. The decrease has led researchers to infer a number of compounds responsible for the observed decreasing spectral shape; the most common being water ice. But ice is incompatible with the 2.78/2.68 micron I/F ratio. Many organic compounds have absorptions that are not seen in spectra of Titan, eliminating them as possible major components at the surface, including many polycyclic aromatic hydrocarbons (PAH) previously thought to be compatible with parts of Titan's spectrum. We find that ring compounds similar to benzene rings, but with some C-H bonds replaced by NH have a closer match to Titan's overall spectrum and can explain the relative intensities observed in the spectral windows, including the 2.68 and 2.78-micron double window, the low 3-5 micron reflectance, and increased absorption near 2.1-microns. Key among these compounds that show general properties that match Titan are

  19. Mapping of Titan: Results from the first Titan radar passes

    USGS Publications Warehouse

    Stofan, E.R.; Lunine, J.I.; Lopes, R.; Paganelli, F.; Lorenz, R.D.; Wood, C.A.; Kirk, R.; Wall, S.; Elachi, C.; Soderblom, L.A.; Ostro, S.; Janssen, M.; Radebaugh, J.; Wye, L.; Zebker, H.; Anderson, Y.; Allison, M.; Boehmer, R.; Callahan, P.; Encrenaz, P.; Flamini, E.; Francescetti, G.; Gim, Y.; Hamilton, G.; Hensley, S.; Johnson, W.T.K.; Kelleher, K.; Muhleman, D.; Picardi, G.; Posa, F.; Roth, L.; Seu, R.; Shaffer, S.; Stiles, B.; Vetrella, S.; West, R.

    2006-01-01

    The first two swaths collected by Cassini's Titan Radar Mapper were obtained in October of 2004 (Ta) and February of 2005 (T3). The Ta swath provides evidence for cryovolcanic processes, the possible occurrence of fluvial channels and lakes, and some tectonic activity. The T3 swath has extensive areas of dunes and two large impact craters. We interpret the brightness variations in much of the swaths to result from roughness variations caused by fracturing and erosion of Titan's icy surface, with additional contributions from a combination of volume scattering and compositional variations. Despite the small amount of Titan mapped to date, the significant differences between the terrains of the two swaths suggest that Titan is geologically complex. The overall scarcity of impact craters provides evidence that the surface imaged to date is relatively young, with resurfacing by cryovolcanism, fluvial erosion, aeolian erosion, and likely atmospheric deposition of materials. Future radar swaths will help to further define the nature of and extent to which internal and external processes have shaped Titan's surface. ?? 2006 Elsevier Inc. All rights reserved.

  20. Nonequilibrium Ablation of Phenolic Impregnated Carbon Ablator

    NASA Technical Reports Server (NTRS)

    Milos, Frank S.; Chen, Yih K.; Gokcen, Tahir

    2012-01-01

    In previous work, an equilibrium ablation and thermal response model for Phenolic Impregnated Carbon Ablator was developed. In general, over a wide range of test conditions, model predictions compared well with arcjet data for surface recession, surface temperature, in-depth temperature at multiple thermocouples, and char depth. In this work, additional arcjet tests were conducted at stagnation conditions down to 40 W/sq cm and 1.6 kPa. The new data suggest that nonequilibrium effects become important for ablation predictions at heat flux or pressure below about 80 W/sq cm or 10 kPa, respectively. Modifications to the ablation model to account for nonequilibrium effects are investigated. Predictions of the equilibrium and nonequilibrium models are compared with the arcjet data.

  1. Titan's Primordial Soup: Formation of Amino Acids via Low Temperature Hydrolysis of Tholins

    NASA Astrophysics Data System (ADS)

    Neish, Catherine; Somogyi, Á.; Smith, M. A.

    2009-09-01

    Titan, Saturn's largest moon, is a world rich in the "stuff of life". Reactions occurring in its dense nitrogen-methane atmosphere produce a wide variety of organic molecules, which subsequently rain down onto its surface. Water - thought to be another important ingredient for life - is likewise abundant on Titan. Theoretical models of Titan's formation predict that its interior consists of an ice I layer several tens of kilometers thick overlying a liquid ammonia-rich water layer several hundred kilometers thick (Tobie et al., 2005). Though its surface temperature of 94K dictates that Titan is on average too cold for liquid water to persist at its surface, melting caused by impacts and/or cryovolcanism may lead to its episodic availability. Impact melt pools on Titan would likely remain liquid for 102 - 104 years before freezing (O'Brien et al., 2005). The combination of complex organic molecules and transient locales of liquid water make Titan an interesting natural laboratory for studying prebiotic chemistry. In this work, we sought to determine what biomolecules might be formed under conditions analogous to those found in transient liquid water environments on Titan. We hydrolyzed Titan organic haze analogues, or "tholins", in 13 wt. % ammonia-water at 253K and 293K for a year. Using a combination of high resolution mass spectroscopy and tandem mass spectroscopy fragmentation techniques, four amino acids were identified in the hydrolyzed tholin sample. These four species have been assigned as the amino acids asparagine, aspartic acid, glutamine, and glutamic acid. This represents the first detection of biologically relevant molecules created under conditions similar to those found in impact melt pools and cryolavas on Titan. Future missions to Titan should therefore carry instrumentation capable of detecting amino acids and other prebiotically relevant molecules on its surface This work was supported by the NASA Exobiology Program.

  2. The search continues for a Titan-generated Nitrogen Torus in Saturn's Magnetosphere

    NASA Astrophysics Data System (ADS)

    Smith, H. T.; Johnson, R. E.; Rymer, A. M.; Lewis, G.; Coates, A. J.; Mitchell, D. G.; Young, D. T.

    2012-12-01

    Saturn's largest moon, Titan, possesses a dense relatively unprotected nitrogen rich atmosphere with no detected intrinsic magnetic field. Therefore, despite the inability of pre-Cassini observations to detect nitrogen in Saturn's magnetosphere , it was logically assumed that nitrogen particles from Titan's atmosphere would form a large toriodal gas cloud. However, Cassini observations have confirmed water-group ions dominate Saturn's heavy ion magnetospheric plasma. While nitrogen ions have been detected beyond the orbit of Rhea, these ions appear to be primarily originating from the Enceladus plumes with little nitrogen plasma detected in the magnetosphere near Titan's orbit. In fact, pick-up oxygen ions from Enceladus are much more abundant than nitrogen in Titan's orbit. These results appear inconsistent with the expectation that Titan's dense relatively unprotected atmosphere should provide a significant source of heavy particles to Saturn's magnetosphere. Resolving this inconsistency could provide import insight into atmospheric loss. In this talk, we expand on our previous research that categorizes the plasma environments near Titan to include all locations along Titan's orbit. Using these categories, we develop characteristic plasma spectra of each type of environment, update ionization lifetimes for each region and apply these results in a 3D Monte Carlo model to more accurately examine the fate of nitrogen and methane escaping Titan's atmosphere to support the possible presence of a Titan torus despite the lack of observations. We also present preliminary Cassini data analysis that looks for the presence of a nitrogen torus as well as the relative ion composition at increasing distances from Titan. This work is supported by the NASA Cassini Data Analysis Program and NASA JPL contract 1243218 for Cassini MIMI and CAPS investigation.

  3. Organic chemistry on Titan: Surface interactions

    NASA Technical Reports Server (NTRS)

    Thompson, W. Reid; Sagan, Carl

    1992-01-01

    The interaction of Titan's organic sediments with the surface (solubility in nonpolar fluids) is discussed. How Titan's sediments can be exposed to an aqueous medium for short, but perhaps significant, periods of time is also discussed. Interactions with hydrocarbons and with volcanic magmas are considered. The alteration of Titan's organic sediments over geologic time by the impacts of meteorites and comets is discussed.

  4. Large Particle Titanate Sorbents

    SciTech Connect

    Taylor-Pashow, K.

    2015-10-08

    This research project was aimed at developing a synthesis technique for producing large particle size monosodium titanate (MST) to benefit high level waste (HLW) processing at the Savannah River Site (SRS). Two applications were targeted, first increasing the size of the powdered MST used in batch contact processing to improve the filtration performance of the material, and second preparing a form of MST suitable for deployment in a column configuration. Increasing the particle size should lead to improvements in filtration flux, and decreased frequency of filter cleaning leading to improved throughput. Deployment of MST in a column configuration would allow for movement from a batch process to a more continuous process. Modifications to the typical MST synthesis led to an increase in the average particle size. Filtration testing on dead-end filters showed improved filtration rates with the larger particle material; however, no improvement in filtration rate was realized on a crossflow filter. In order to produce materials suitable for column deployment several approaches were examined. First, attempts were made to coat zirconium oxide microspheres (196 µm) with a layer of MST. This proved largely unsuccessful. An alternate approach was then taken synthesizing a porous monolith of MST which could be used as a column. Several parameters were tested, and conditions were found that were able to produce a continuous structure versus an agglomeration of particles. This monolith material showed Sr uptake comparable to that of previously evaluated samples of engineered MST in batch contact testing.

  5. Structure of Titan's evaporites

    NASA Astrophysics Data System (ADS)

    Cordier, D.; Cornet, T.; Barnes, J. W.; MacKenzie, S. M.; Le Bahers, T.; Nna-Mvondo, D.; Rannou, P.; Ferreira, A. G.

    2016-05-01

    Numerous geological features that could be evaporitic in origin have been identified on the surface of Titan. Although they seem to be water-ice poor, their main properties - chemical composition, thickness, stratification - are essentially unknown. In this paper, which follows on a previous one focusing on the surface composition (Cordier, D., Barnes, J.W., Ferreira, A.G. [2013b]. Icarus 226(2),1431-1437), we provide some answers to these questions derived from a new model. This model, based on the up-to-date thermodynamic theory known as "PC-SAFT", has been validated with available laboratory measurements and specifically developed for our purpose. 1-D models confirm the possibility of an acetylene and/or butane enriched central layer of evaporitic deposit. The estimated thickness of this acetylene-butane layer could explain the strong RADAR brightness of the evaporites. The 2-D computations indicate an accumulation of poorly soluble species at the deposit's margin. Among these species, HCN or aerosols similar to tholins could play a dominant role. Our model predicts the existence of chemically trimodal "bathtub rings" which is consistent with what it is observed at the south polar lake Ontario Lacus. This work also provides plausible explanations to the lack of evaporites in the south polar region and to the high radar reflectivity of dry lakebeds.

  6. Renal Ablation Update

    PubMed Central

    Khiatani, Vishal; Dixon, Robert G.

    2014-01-01

    Thermal ablative technologies have evolved considerably in the recent past and are now an important component of current clinical guidelines for the treatment of small renal masses. Both radiofrequency ablation and cryoablation have intermediate-term oncologic control that rivals surgical options, with favorable complication profiles. Studies comparing cryoablation and radiofrequency ablation show no significant difference in oncologic control or complication profile between the two modalities. Early data from small series with microwave ablation have shown similar promising results. Newer technologies including irreversible electroporation and high-intensity–focused ultrasound have theoretical advantages, but will require further research before becoming a routine part of the ablation armamentarium. The purpose of this review article is to discuss the current ablative technologies available, briefly review their mechanisms of action, discuss technical aspects of each, and provide current data supporting their use. PMID:25049445

  7. Widespread morning drizzle on Titan.

    PubMed

    Adámkovics, Máté; Wong, Michael H; Laver, Conor; de Pater, Imke

    2007-11-01

    Precipitation is expected in Titan's atmosphere, yet it has not been directly observed, and the geographical regions where rain occurs are unknown. Here we present near-infrared spectra from the Very Large Telescope and W. M. Keck Observatories that reveal an enhancement of opacity in Titan's troposphere on the morning side of the leading hemisphere. Retrieved extinction profiles are consistent with condensed methane in clouds at an altitude near 30 kilometers and concomitant methane drizzle below. The moisture encompasses the equatorial region over Titan's brightest continent, Xanadu. Diurnal temperature gradients that cause variations in methane relative humidity, winds, and topography may each be a contributing factor to the condensation mechanism. The clouds and precipitation are optically thin at 2.0 micrometers, and models of "subvisible" clouds suggest that the droplets are 0.1 millimeter or larger.

  8. Is titan wet or dry?

    PubMed

    Eshleman, V R; Lindal, G F; Tyler, G L

    1983-07-01

    Titan's dense and cold nitrogen atmosphere contains a small amount of methane under conditions at least approaching those at which one or both constituents would condense. The possibility of methane and nitrogen rain clouds and global methane oceans has been discussed widely. From specific features of radio occultation and other Voyager results, however, it is concluded that nitrogen does not condense on Titan and that Titan has neither global methane oceans nor a global cloud of liquid methane droplets. Certain results indirectly support the conjecture that methane does not condense at any location. However, other considerations favor a methane ice haze high in the troposphere, and liquid and solid methane might exist on the surface and as low clouds at polar latitudes.

  9. Charged particles in Titan's ionosphere

    NASA Astrophysics Data System (ADS)

    Tripathi, Sachchida

    2010-05-01

    Charged particles in Titan's ionosphere Marykutty Michael1, Sachchida Nand Tripathi1,2,3, Pratima Arya1 1Indian Institute of Technology Kanpur 2Oak Ridge Associated Universities 3NASA Goddard Space Flight Center Observations by two instruments onboard the Cassini spacecraft, Ion Neutral Mass Spectrometer (INMS) and CAssini Plasma Spectrometer (CAPS), revealed the existence of heavy hydrocarbon and nitrile species with masses of several thousand atomic mass units at altitudes of 950 - 1400 km in the atmosphere of Titan (Waite et al., 2007; Crary et al., 2009). Though these particles were believed to be molecules, they are most likely aerosols formed by the clumping of smaller molecules (Waite et al., 2009). These particles were estimated to have a density of 10-3 kg m-3 and a size of up to 256 nm. The existence of very heavy ions has also been observed by the CAPS components with a mass by charge ratio of up to 10000 (Coates et al., 2007, 2009; Sittler et al., 2009). The goal of this paper is to find out whether the so called heavy ions (or charged particles) are generated by the charge transfer of ions and electrons to the particles. The charging of these particles has been studied by using the charge balance equations that include positive ions, negative ions, electrons, neutral and charged particles. Information on the most abundant ion clusters are obtained from Vuitton et al., (2009) and Wilson and Atreya, (2004). Mass by charge ratio thus calculated will be compared with those observed by Coates et al. (2007). References: Coates AJ, et al., Discovery of heavy negative ions in Titan's ionosphere, Geophys. Res. Lett., 34:L22103, 2007. Coates AJ, et al., Heavy negative ions in titan's ionosphere: altitude and latitude dependence. Planet. Space Sci., doi:10.1016/j.pss.2009.05.009, 2009. Crary F.J., et al., Heavy ions, temperatures and winds in titan's ionosphere: Combined cassini caps and inms observations. Planet. Space Sci., doi:10.1016/j.pss.2009.09.006, 2009

  10. The induced magnetosphere of Titan

    NASA Astrophysics Data System (ADS)

    Ness, N. F.; Acuna, M. H.; Behannon, K. W.

    1982-03-01

    No evidence was found for an intrinsic magnetic field, nor for the development of a bow shock wave, as the corotating Saturnian magnetoplasma convected past Titan during the Voyager 1 close encounter of November 12, 1980. The observation of a well-developed, induced bipolar magnetic tail is evidence, however, of a strong electrodynamic interaction. Three thin, current-carrying regions were crossed which correspond to the inbound and outbound tail magnetopause and an imbedded tail neutral sheet. The interaction is unique among those observed to date in the solar system, in that it is intermediate with respect to sonic and Alfvenic Mach numbers by comparison with Titan in the solar wind and Io in the Jovian magnetosphere. The draping of the Saturnian magnetic field around the ionosphere of Titan is suggested by results of the analysis of magnetic field data.

  11. Radiofrequency Ablation of Cancer

    SciTech Connect

    Friedman, Marc; Mikityansky, Igor; Kam, Anthony; Libutti, Steven K.; Walther, McClellan M.; Neeman, Ziv; Locklin, Julia K.; Wood, Bradford J.

    2004-09-15

    Radiofrequency ablation (RFA) has been used for over 18 years for treatment of nerve-related chronic pain and cardiac arrhythmias. In the last 10 years, technical developments have increased ablation volumes in a controllable, versatile, and relatively inexpensive manner. The host of clinical applications for RFA have similarly expanded. Current RFA equipment, techniques, applications, results, complications, and research avenues for local tumor ablation are summarized.

  12. Diurnal variations of Titan's ionosphere

    NASA Astrophysics Data System (ADS)

    Cui, J.; Galand, M.; Yelle, R. V.; Vuitton, V.; Wahlund, J.-E.; Lavvas, P. P.; Müller-Wodarg, I. C. F.; Cravens, T. E.; Kasprzak, W. T.; Waite, J. H.

    2009-06-01

    We present our analysis of the diurnal variations of Titan's ionosphere (between 1000 and 1300 km) based on a sample of Ion Neutral Mass Spectrometer (INMS) measurements in the Open Source Ion (OSI) mode obtained from eight close encounters of the Cassini spacecraft with Titan. Although there is an overall ion depletion well beyond the terminator, the ion content on Titan's nightside is still appreciable, with a density plateau of ˜700 cm-3 below ˜1300 km. Such a plateau is a combined result of significant depletion of light ions and modest depletion of heavy ones on Titan's nightside. We propose that the distinctions between the diurnal variations of light and heavy ions are associated with their different chemical loss pathways, with the former primarily through “fast” ion-neutral chemistry and the latter through “slow” electron dissociative recombination. The strong correlation between the observed night-to-day ion density ratios and the associated ion lifetimes suggests a scenario in which the ions created on Titan's dayside may survive well to the nightside. The observed asymmetry between the dawn and dusk ion density profiles also supports such an interpretation. We construct a time-dependent ion chemistry model to investigate the effect of ion survival associated with solid body rotation alone as well as superrotating horizontal winds. For long-lived ions, the predicted diurnal variations have similar general characteristics to those observed. However, for short-lived ions, the model densities on the nightside are significantly lower than the observed values. This implies that electron precipitation from Saturn's magnetosphere may be an additional and important contributor to the densities of the short-lived ions observed on Titan's nightside.

  13. Ion cyclotron waves at Titan

    NASA Astrophysics Data System (ADS)

    Russell, C. T.; Wei, H. Y.; Cowee, M. M.; Neubauer, F. M.; Dougherty, M. K.

    2016-03-01

    During the interaction of Titan's thick atmosphere with the ambient plasma, it was expected that ion cyclotron waves would be generated by the free energy of the highly anisotropic velocity distribution of the freshly ionized atmospheric particles created in the interaction. However, ion cyclotron waves are rarely observed near Titan, due to the long growth times of waves associated with the major ion species from Titan's ionosphere, such as CH4+ and N2+. In the over 100 Titan flybys obtained by Cassini to date, there are only two wave events, for just a few minutes during T63 flyby and for tens of minutes during T98 flyby. These waves occur near the gyrofrequencies of proton and singly ionized molecular hydrogen. They are left-handed, elliptically polarized, and propagate nearly parallel to the field lines. Hybrid simulations are performed to understand the wave growth under various conditions in the Titan environment. The simulations using the plasma and field conditions during T63 show that pickup protons with densities ranging from 0.01 cm-3 to 0.02 cm-3 and singly ionized molecular hydrogens with densities ranging from 0.015 cm-3 to 0.25 cm-3 can drive ion cyclotron waves with amplitudes of ~0.02 nT and of ~0.04 nT within appropriate growth times at Titan, respectively. Since the T98 waves were seen farther upstream than the T63 waves, it is possible that the instability was stronger and grew faster on T98 than T63.

  14. Titan and Enceladus mission (TANDEM)

    NASA Astrophysics Data System (ADS)

    Coustenis, A.

    2007-08-01

    Our understanding of Titan's atmosphere and surface has recently been enhanced by the data returned by the Cassini-Huygens mission. The Cassini orbiter will continue to be operational for about 3 more years during its extended mission. After this mission, any unanswered questions will forever remain unknown, unless we go back with an optimized orbital tour and advanced instrumentation. Considering the complementary nature of the geological, chemical and evolutionary history of Titan and Enceladus, we propose to carry out studies for a mission to perform an in situ exploration of these two objects in tandem. In our proposal we determine key science measurements, the types of samples that would be needed and the instrument suites for achieving the science goals. In particular, we develop conceptual designs for delivering the science payload, including orbiters, aerial platforms and probes, and define a launch/delivery/communication management architecture. This mission will require new technologies and capabilities so that the science goals can be achieved within the cost cap and acceptable risks. International participation will play a key role in achieving all the science goals of this mission. We will build this mission concept around a central core of single orbiter, a single Titan aerial probe and a core group of category 1 instruments. Aerobraking with Titan's atmosphere will be given serious consideration to minimize resource requirements and risk. This approach will allow a single orbiter to be used for both Enceladus science and Titan science with final orbit around Titan and later release of aerial probe(s) into Titan's atmosphere. The Titan aerial probe may be a Montgolfière balloon concept that will use the waster heat ~ 1000 watts from a single RTG power system. There will be a release of penetrator(s) on Enceladus also. This proposal addresses directly several of the scientific questions highlighted in the ESA Cosmic Vision 2015-2025 call, particularly

  15. Will Titan lose its veil?

    NASA Astrophysics Data System (ADS)

    Dimitrov, V.

    2007-08-01

    Methane CH4 is the only highly reactive and short-lived background component in Titan's atmosphere, so its overall reserve predetermines both features and duration of atmospheric chemical activity. Titan's global chemical activity is considered in terms of methane cycle. One cycle is defined as a period T0=7.0.1014s of complete photochemical destruction of methane's observable atmospheric content CH04 = 2.33.1017 kg. Cycle duration T0, number of the past NP =200±20, future NF =500±50 and total Nmax=NP+NF =700±70 cycles are the main quantitative indices of the global chemical activity [2]. The fact that the period T0 is much less than Titan's lifetime TT =1.42*1017s implies that the current content CH04 is continuously replenishing by methane global circulation. There are two sources of this replenishment, i.e. the outgassing of primordial methane reserve trapped in Titan's interior as the clathrate, and the (sub)ground liquidphase reduction of non-saturated final products of the atmospheric photochemical process. Internal reserve provides the dominant portion (>95%) of general recycling, while reducing reconversion is the minor constituent of the global balance. Yet, there is the problem of the availability of the off-the-shelf trapped methane. Overall admissible stock of the trapped methane depends on its internal allocation and falls in the range (CH4)max1,2=(15.3÷33.3).1020 kg, while continuous atmospheric activity during the whole Titan's life TSun 5.0.1017s needs only (CH4)crit=(CH04 ).Nmax = .(CH4)max 1.65.1020 kg. In turn, this bulk (CH4)crit depends on the clathrate cage-filling efficiency (molecular packing index) {kg CH4/kg clathrate} and can be provided if equals respectively to [1] crit1= (TSun/T0).[(CH4)0/[(CH4)max1] = 5.45.10-3 crit2= (TSun/T0).[(CH4)0/[(CH4)max2] = 2.51.10-3 Thus, the interrelation of overall trapped stock (CH4)max and crucial -values assigns the critical value (CH4)crit that in turn predetermines the very fate of Titan's veil

  16. AVIATR—Aerial Vehicle for In-situ and Airborne Titan Reconnaissance. A Titan airplane mission concept

    NASA Astrophysics Data System (ADS)

    Barnes, Jason W.; Lemke, Lawrence; Foch, Rick; McKay, Christopher P.; Beyer, Ross A.; Radebaugh, Jani; Atkinson, David H.; Lorenz, Ralph D.; Le Mouélic, Stéphane; Rodriguez, Sebastien; Gundlach, Jay; Giannini, Francesco; Bain, Sean; Flasar, F. Michael; Hurford, Terry; Anderson, Carrie M.; Merrison, Jon; Ádámkovics, Máté; Kattenhorn, Simon A.; Mitchell, Jonathan; Burr, Devon M.; Colaprete, Anthony; Schaller, Emily; Friedson, A. James; Edgett, Kenneth S.; Coradini, Angioletta; Adriani, Alberto; Sayanagi, Kunio M.; Malaska, Michael J.; Morabito, David; Reh, Kim

    2012-03-01

    We describe a mission concept for a stand-alone Titan airplane mission: Aerial Vehicle for In-situ and Airborne Titan Reconnaissance (AVIATR). With independent delivery and direct-to-Earth communications, AVIATR could contribute to Titan science either alone or as part of a sustained Titan Exploration Program. As a focused mission, AVIATR as we have envisioned it would concentrate on the science that an airplane can do best: exploration of Titan's global diversity. We focus on surface geology/hydrology and lower-atmospheric structure and dynamics. With a carefully chosen set of seven instruments—2 near-IR cameras, 1 near-IR spectrometer, a RADAR altimeter, an atmospheric structure suite, a haze sensor, and a raindrop detector—AVIATR could accomplish a significant subset of the scientific objectives of the aerial element of flagship studies. The AVIATR spacecraft stack is composed of a Space Vehicle (SV) for cruise, an Entry Vehicle (EV) for entry and descent, and the Air Vehicle (AV) to fly in Titan's atmosphere. Using an Earth-Jupiter gravity assist trajectory delivers the spacecraft to Titan in 7.5 years, after which the AVIATR AV would operate for a 1-Earth-year nominal mission. We propose a novel `gravity battery' climb-then-glide strategy to store energy for optimal use during telecommunications sessions. We would optimize our science by using the flexibility of the airplane platform, generating context data and stereo pairs by flying and banking the AV instead of using gimbaled cameras. AVIATR would climb up to 14 km altitude and descend down to 3.5 km altitude once per Earth day, allowing for repeated atmospheric structure and wind measurements all over the globe. An initial Team-X run at JPL priced the AVIATR mission at FY10 715M based on the rules stipulated in the recent Discovery announcement of opportunity. Hence we find that a standalone Titan airplane mission can achieve important science building on Cassini's discoveries and can likely do so

  17. Characterizing GEO Titan Transtage Fragmentations using Ground-based Measurements

    NASA Technical Reports Server (NTRS)

    Cowardin, H.; Anz-Meador, P.

    2016-01-01

    In a continued effort to better characterize the Geosynchronous Orbit (GEO) environment, NASA's Orbital Debris Program Office (ODPO) utilizes various ground-based optical assets to acquire photometric and spectral data of known debris associated with fragmentations in or near GEO. The Titan IIIC Transtage upper stage is known to have fragmented four times. Two of the four fragmentations were in GEO while a third Transtage fragmented in GEO transfer orbit. The forth fragmentation occurred in Low Earth Orbit. In order to better assess what may be causing these fragmentations, the NASA ODPO recently acquired a Titan Transtage test and display article that was previously in the custody of the 309th Aerospace Maintenance and Regeneration Group (AMARG) in Tucson, Arizona. After initial inspections at AMARG demonstrated that the test article was of sufficient fidelity to be of interest, the test article was brought to JSC to continue material analysis and historical documentation of the Titan Transtage. The Transtage will be a subject of forensic analysis using spectral measurements to compare with telescopic data; as well, a scale model will be created to use in the Optical Measurement Center for photometric analysis of an intact Transtage, including a BRDF. The following presentation will provide a review of the Titan Transtage, the current analysis that has been done to date, and the future work to be completed in support of characterizing the GEO and near GEO orbital debris environment.

  18. Sprayable lightweight ablative coating

    NASA Technical Reports Server (NTRS)

    Simpson, William G. (Inventor); Sharpe, Max H. (Inventor); Hill, William E. (Inventor)

    1991-01-01

    An improved lightweight, ablative coating is disclosed that may be spray applied and cured without the development of appreciable shrinkage cracks. The ablative mixture consists essentially of phenolic microballoons, hollow glass spheres, glass fibers, ground cork, a flexibilized resin binder, and an activated colloidal clay.

  19. Organic chemistry in Titan's atmosphere

    NASA Technical Reports Server (NTRS)

    Scattergood, T.

    1982-01-01

    Laboratory photochemical simulations and other types of chemical simulations are discussed. The chemistry of methane, which is the major known constituent of Titan's atmosphere was examined with stress on what can be learned from photochemistry and particle irradiation. The composition of dust that comprises the haze layer was determined. Isotope fractionation in planetary atmospheres is also discussed.

  20. The organic aerosols of Titan

    NASA Technical Reports Server (NTRS)

    Khare, B. N.; Sagan, C.; Thompson, W. R.; Arakawa, E. T.; Suits, F.; Calcott, T. A.; Williams, M. W.; Shrader, S.; Ogino, H.; Willingham, T. O.

    1986-01-01

    A dark reddish organic solid, called tholin, is synthesized from simulated Titanian atmospheres by irradiation with high energy electrons in a plasma discharge. The visible reflection spectrum of this tholin is found to be similar to that of high altitude aerosols responsible for the albedo and reddish color of Titan. The real (n) and imaginary (k) parts of the complex refractive index of thin films of Titan prepared by continuous dc discharge through a 0.9 N2/0.1 CH4 gas mixture at 0.2 mb is determined from X-ray to microwave frequencies. Values of n (approx. 1.65) and k (approx. 0.004 to 0.08) in the visible are consistent with deductions made by groundbased and spaceborne observations of Titan. Many infrared absorption features are present in k(lambda), including the 4.6 micrometer nitrile band. Molecular analysis of the volatile components of this tholin was performed by sequential and nonsequential pyrolytic gas chromatography/mass spectrometry. More than one hundred organic compounds are released; tentative identifications include saturated and unsaturated aliphatic hydrocarbons, substituted polycylic aromatics, nitriles, amines, pyrroles, pyrazines, pyridines, pyrimidines, and the purine, adenine. In addition,acid hydrolysis produces a racemic mixture of biological and nonbiological amino acids. Many of these molecules are implicated in the origin of life on Earth, suggesting Titan as a contemporary laboratory environment for prebiological organic chemistry on a planetary scale.

  1. The dynamics of Titan's troposphere.

    PubMed

    Tokano, Tetsuya

    2009-02-28

    While the Voyager mission could essentially not reveal the dynamics of Titan's troposphere, useful information was obtained by the Cassini spacecraft and, particularly, by the Huygens probe that landed on Titan's surface; this information can be interpreted by means of numerical models of atmospheric circulation. The meridional circulation is likely to consist of a large Hadley circulation asymmetric about the equator, but is susceptible to disruption by turbulence in clouds. The zonal wind in the troposphere is comparable to or even weaker than that in the terrestrial troposphere and contains zones of easterlies, much in contrast to the super-rotating stratosphere. Unique to Titan is the transition from a geostrophic to cyclostrophic wind balance in the upper troposphere. While Earth-like storm systems associated with baroclinic instability are absent, Saturn's gravitational tide introduces a planetary wave of wavenumber 2 and a periodical variation in the wind direction in the troposphere. Unlike on Earth, the wind over the equatorial surface is westerly. The seasonal reversal in the Hadley circulation sense and zonal wind direction is predicted to have a substantial influence on the formation of dunes as well as variation of Titan's rotation rate and length of day.

  2. The organic aerosols of Titan.

    PubMed

    Khare, B N; Sagan, C; Thompson, W R; Arakawa, E T; Suits, F; Callcott, T A; Williams, M W; Shrader, S; Ogino, H; Willingham, T O; Nagy, B

    1984-01-01

    A dark reddish organic solid, called tholin, is synthesized from simulated Titanian atmospheres by irradiation with high energy electrons in a plasma discharge. The visible reflection spectrum of this tholin is found to be similar to that of high altitude aerosols responsible for the albedo and reddish color of Titan. The real (n) and imaginary (k) parts of the complex refractive index of thin films of Titan tholin prepared by continuous D.C. discharge through a 0.9 N2/0.1 CH4 gas mixture at 0.2 mb is determined from x-ray to microwave frequencies. Values of n (approximately equal to 1.65) and k (approximately equal to 0.004 to 0.08) in the visible are consistent with deductions made by ground-based and spaceborne observations of Titan. Many infrared absorption features are present in k (lambda), including the 4.6 micrometers nitrile band. Molecular analysis of the volatile component of this tholin was performed by sequential and non-sequential pyrolytic gas chromatography/mass spectrometry. More than one hundred organic compounds are released; tentative identifications include saturated and unsaturated aliphatic hydrocarbons, substituted polycyclic aromatics, nitriles, amines, pyrroles, pyrazines, pyridines, pyrimidines, and the purine, adenine. In addition, acid hydrolysis produces a racemic mixture of biological and non-biological amino acids. Many of these molecules are implicated in the origin of life on Earth, suggesting Titan as a contemporary laboratory environment for prebiological organic chemistry on a planetary scale.

  3. Titan Aeromony and Climate Workshop

    NASA Astrophysics Data System (ADS)

    Bézard, Bruno; Lavvas, Panayotis; Rannou, Pascal; Sotin, Christophe; Strobel, Darrell; West, Robert A.; Yelle, Roger

    2016-06-01

    The observations of the Cassini spacecraft since 2004 revealed that Titan, the largest moon of Saturn, has an active climate cycle with a cloud cover related to the large scale atmospheric circulation, lakes of methane and hyrdrocarbons with variable depth, a dried fluvial system witnessing a past wetter climate, dunes, and deep changes in the weather and atmospheric structure as Titan went through the North Spring equinox. Moreover, the upper atmosphere is now considered the cradle of complex chemistry leading to aerosol formation, as well as the manifestation place of atmospheric waves. However, as the Cassini mission comes to its end, many fundamental questions remain unresolved... The objective of the workshop is to bring together international experts from different fields of Titan's research in order to have an overview of the current understanding, and to determine the remaining salient scientific issues and the actions that could be implemented to address them. PhD students and post-doc researchers are welcomed to present their studies. This conference aims to be a brainstorming event leaving abundant time for discussion during oral and poster presentations. Main Topics: - Atmospheric seasonal cycles and coupling with dynamics. - Composition and photochemistry of the atmosphere. - Formation and evolution of aerosols and their role in the atmosphere. - Spectroscopy, optical properties, and radiative transfer modeling of the atmosphere. - Surface composition, liquid reservoirs and interaction with atmosphere. - Evolution of the atmosphere. - Titan after Cassini, open questions and the path forward.

  4. Titan's gas and plasma torus

    NASA Technical Reports Server (NTRS)

    Eviatar, A.; Podolak, M.

    1983-01-01

    The implications of the Voyager observations for a steady state model of a torus of hydrogen and nitrogen neutral gas and plasma are assessed. Constraints are placed on the nitrogen neutral density, the neutral hydrogen and nitrogen escape fluxes (from Titan), and the diffusion rate in terms of observed or inferred quantities. The results obtained are consistent with the Voyager observations.

  5. Titan's Polar Atmosphere

    NASA Astrophysics Data System (ADS)

    Flasar, F. M.; Achterberg, R. K.; Schinder, P. J.

    2015-12-01

    Cassini CIRS and Radio-Occultation measurements obtained in 2004-2015 have tracked the evolution of temperatures and winds in Titan's polar atmosphere, as the winter season shifted from the northern hemisphere to the southern. The dissolution of the strong circumpolar vortex initially seen in the northern hemisphere has been gradual. There is no evidence of the rapid distortion and disruption forced by planetary waves that can occur on Earth. Indeed, neither Cassini experiment has identified any thermal signature attributable to planetary-scale waves. The south-polar region has turned wintry fairly abruptly: temperature and zonal wind maps from CIRS data show that the 1-mbar temperatures at high southern latitudes in late autumn are already much colder than those at the corresponding latitudes in the north in midwinter, when the first extensive polar measurements were obtained. The south-polar region now has a strong circumpolar vortex, with maximum stratospheric winds occurring near 60° S, in contrast to the northern hemisphere in winter, where the polar vortex was much broader, extending to 20°-30° N. Potential vorticity maps now indicate steep meridional gradients at high southern latitudes, implying a barrier to efficient mixing between the polar region and lower latitudes. Radio-occultations have higher vertical resolution than CIRS, and they have recently probed latitudes as high as 65° in both hemispheres (latitudes closer to the pole are precluded because of the geometry of Earth occultations and the season). Above 80 km at these latitudes, where the radiative damping times are small enough that temperatures have large seasonal variations, the stratosphere in the north has warmed, and it has become much colder in the south. The abrupt transition region with negative vertical temperature gradient between 80 and 100 km, which was seen at high northern latitudes in winter, has weakened, but it is still visible. In the south, one can see the early stage of

  6. Temperate Lakes Discovered on Titan

    NASA Astrophysics Data System (ADS)

    Vixie, Graham; Barnes, Jason W.; Jackson, Brian; Wilson, Paul

    2012-04-01

    We have discovered two temperate lakes on Titan using Cassini's Visual and Infrared Mapping Spectrometer (VIMS). Three key features help to identify these surface features as lakes: morphology, albedo, and specular reflection. The presence of lakes at the mid-latitudes mean liquid can accumulate and remain stable outside of the poles. We first identify a lake surface by looking for possible shorelines with a lacustrine morphology. Then, we apply a simple atmospheric correction that produces an approximate surface albedo. Next, we prepare cylindrical projection maps of the brightness of the sky as seen from any points on the surface to identify specular reflections. Our techniques can then be applied to other areas, such as Arrakis Planitia, to test for liquid. Currently, all the known lakes on Titan are concentrated at the poles. Lakes have been suggested in the tropic zone by Griffith et al. Our discovery of non-transient, temperate lakes has important implications for Titan's hydrologic cycle. Clouds have been recorded accumulating in the mid-latitudes and areas have been darkened by rainfall but later brightened after evaporation (Turtle et al. 2011). Stable temperate lakes would affect total rainfall, liquid accumulation, evaporation rates, and infiltration. Polaznik Macula (Figure 1) is a great candidate for lake filling, evaporation rates, and stability. References: Griffith, C., et al.: "Evidence for Lakes on Titan's Tropical Surface". AAS/Division for Planetary Sciences Meeting Abstracts #42, Vol. 42, pp. 1077, 2010. Turtle, E. P., et al.: "Rapid and Extensive Surface Changes Near Titan's Equator: Evidence of April Showers". Science, Vol. 331, pp. 1414-, 2011. Figure 1: Polaznik Macula is the large, dark area central to the figure. The encircled dark blue areas represent positively identified lake regions in the T66 flyby. The light blue areas represent lake candidates still under analysis. The green circle marks a non-lake surface feature enclosed by a

  7. Nitrogen compounds in Titan's stratosphere

    NASA Astrophysics Data System (ADS)

    Coustenis, A.; Cirs Investigation Team

    Titan's atmosphere is essentially composed of molecular nitrogen (N2). The chemistry between the two mother molecules (N2 and CH4) leads to the formation of a certain number of nitriles observed in Titan's stratosphere as early as at the time of the Voyager 1 encounter in 1980. In the spectra taken by the Infrared Radiometer Interferometer Spectrometer (IRIS) the signatures of HCN, HC3N, C2N2 and C4N2 (in solid form) were found and reported. Subsequent observations from the ground better described the vertical profiles of these constituents and allowed for the detection of CH3CN (acetonitrile) in the mm range [3,4]. Recent data recorded by the Composite Infrared Spectrometer (CIRS) aboard the Cassini spacecraft during the Titan flybys (October 2004 - June 2006) give a handle on the temporal and latitudinal variations of these constituents. The nadir spectra characterize various regions on Titan from 85°S to 75°N with a variety of emission angles. We study the emission observed in the mid-infrared CIRS detector arrays (covering roughly the 600-1500 cm-1 spectral range with apodized resolutions of 2.54 or 0.53 cm-1 ). The composite spectrum shows several molecular signatures of nitriles. Information is retrieved on the meridional variations of the trace constituents and tied to predictions by dynamical-photochemical models [1,2,5]. The nitriles show a significant enhancement at high northern latitudes albeit not as marked as at the time of the Voyager encounter. We will give a review of our current understanding of the minor nitrile chemistry on Titan. References : [1] Coustenis et al., 2006. Icarus, in press. [2] Flasar et al., 2005. Science 308, 975. [3] Marten, A., et al., 2002, Icarus, 158, 532-544. [4] Marten, A. & Moreno, R., 2003. 35th Annual DPS Meeting, Monterey, Ca, BAAS, 35, 952. [5] Teanby et al., 2006. Icarus, 181, 243-255.

  8. Titan's Spectacular Volte-Face

    NASA Astrophysics Data System (ADS)

    Griffith, Caitlin A.

    2013-10-01

    Like Earth, Titan sports lakes, storms and rainfall. These features derive from a methane cycle, reminiscent of Earth's hydrological cycle; methane exists as an ice, liquid and gas and transfers between the surface and atmosphere, according to the seasonal weather. Titan's seasons contrast Earth’s. Imagine a summer trip to 70 latitude, where hurricane-sized storms burst forth out of a clear sky every few months for about 15 years. Then they vanish for another 15 years. Envision a trip to the winter polar region. Here the sky is perhaps clear except that the high haze, which filters sunlight like a translucent globe, is somewhat thicker than it is in the summer. Imperceptibly, you are blocking the diffuse organic matter, which is slowly settling out of the hazy orb, and accumulating on the polar surface. These effects are a few of the many that derive from Titan’s circulation and its seasonal changes during the satellite's 29.5 Earth year orbit about the Sun. In particular, and as indicated in recent observations, Titan's circulation flip-flopped. Before equinox in 2009, on average, air rose in the southern polar region and downwelled in the northern polar region. Now the reverse appears to be happening. Here we discuss the observations ranging from the surface to ~500 km altitude that reveal the symphony of responses of Titan's surface and atmosphere to this dramatic shift. In addition we discuss the syntheses of these effects, from theoretical efforts involving microphysical models, local cloud models and general circulation models, with the question of why Titan's seasonal changes are so much more spectacular compared to those of Earth.

  9. Alternate nozzle ablative materials program

    NASA Technical Reports Server (NTRS)

    Kimmel, N. A.

    1984-01-01

    Four subscale solid rocket motor tests were conducted successfully to evaluate alternate nozzle liner, insulation, and exit cone structural overwrap components for possible application to the Space Shuttle Solid Rocket Motor (SRM) nozzle asasembly. The 10,000 lb propellant motor tests were simulated, as close as practical, the configuration and operational environment of the full scale SRM. Fifteen PAN based and three pitch based materials had no filler in the phenolic resin, four PAN based materials had carbon microballoons in the resin, and the rest of the materials had carbon powder in the resin. Three nozzle insulation materials were evaluated; an aluminum oxide silicon oxide ceramic fiber mat phenolic material with no resin filler and two E-glass fiber mat phenolic materials with no resin filler. It was concluded by MTI/WD (the fabricator and evaluator of the test nozzles) and NASA-MSFC that it was possible to design an alternate material full scale SRM nozzle assembly, which could provide an estimated 360 lb increased payload capability for Space Shuttle launches over that obtainable with the current qualified SRM design.

  10. Numerical modelling of sedimentary structures in rivers on Titan and Earth

    NASA Astrophysics Data System (ADS)

    Misiura, Katarzyna; Czechowski, Leszek

    2016-04-01

    preliminary results indicate that suspended load is the main way of transport in simulated Titan's conditions. We also indicate that braided rivers appears for larger range of slope on Titan (e.g. S=0.01-0.04) than on Earth (e.g. S=0.004-0.009). Also, for the same type of river, the grain size on Titan is at least 10 times larger than on Earth (1 cm for Titan versus 1 mm for the Earth). It is very interesting that on Titan braided rivers appear even for very little discharge (e.g. Q=30m3/s) and for very large grain size (e.g. 10 cm). In the future we plan the experimental modelling in sediment basin to confirm results from computer modelling. Acknowledgements We are very grateful to Yaoxin Zhang and Yafei Jia from National Center for Computational Hydroscience and Engineering for providing their program - CCHE2D. References [1] Misiura, K., Czechowski, L., 2015. Numerical modelling of sedimentary structures in rivers on Earth and Titan. Geological Quarterly, 59(3): 565-580.

  11. Thermal Ablation Modeling for Silicate Materials

    NASA Technical Reports Server (NTRS)

    Chen, Yih-Kanq

    2016-01-01

    A thermal ablation model for silicates is proposed. The model includes the mass losses through the balance between evaporation and condensation, and through the moving molten layer driven by surface shear force and pressure gradient. This model can be applied in ablation simulations of the meteoroid or glassy Thermal Protection Systems for spacecraft. Time-dependent axi-symmetric computations are performed by coupling the fluid dynamics code, Data-Parallel Line Relaxation program, with the material response code, Two-dimensional Implicit Thermal Ablation simulation program, to predict the mass lost rates and shape change. For model validation, the surface recession of fused amorphous quartz rod is computed, and the recession predictions reasonably agree with available data. The present parametric studies for two groups of meteoroid earth entry conditions indicate that the mass loss through moving molten layer is negligibly small for heat-flux conditions at around 1 MW/cm(exp. 2).

  12. Laser ablation of dyes

    NASA Astrophysics Data System (ADS)

    Späth, M.; Stuke, M.

    1992-01-01

    High density 50 μs pulses of the UV dyes PPF, POPOP and BBO and of two dyes in the visible region, Xanthen N92 and Fluorol 7GA were generated by laser ablation. Dye powders were pressed with 7800 kp/cm 2 in round pellets which were ablated by exposure to KrF excimer laser radiation (248 nm) at a fluence of 100 mJ/cm 2. The ablation cloud was optically activated with a XeCl excimer laser. Its fluorescence spectrum was measured and was identified as a dye vapour fluorescence spectrum by comparison to conventional dye solution and dye vapour spectra. The dye cloud is not deflected in an electric field (10 6 V/m). By changing the delay time between the ablation laser and the focused activation laser, the velocity distribution of the ablated dye was measured. Its maximum is at 600 m/s for PPF. Knowing the thickness of the ablated dye layer per shot (300 Å) and the size of the ablation cloud (pictures of a video camera), one can estimate the maximum density of the dye in the gas pulse to be 10 -5 mol/ l in the range of concentration of lasing dyes. However, no lasing was observed up to now.

  13. Tumor Ablation and Nanotechnology

    PubMed Central

    Manthe, Rachel L.; Foy, Susan P.; Krishnamurthy, Nishanth; Sharma, Blanka; Labhasetwar, Vinod

    2010-01-01

    Next to surgical resection, tumor ablation is a commonly used intervention in the treatment of solid tumors. Tumor ablation methods include thermal therapies, photodynamic therapy, and reactive oxygen species (ROS) producing agents. Thermal therapies induce tumor cell death via thermal energy and include radiofrequency, microwave, high intensity focused ultrasound, and cryoablation. Photodynamic therapy and ROS producing agents cause increased oxidative stress in tumor cells leading to apoptosis. While these therapies are safe and viable alternatives when resection of malignancies is not feasible, they do have associated limitations that prevent their widespread use in clinical applications. To improve the efficacy of these treatments, nanoparticles are being studied in combination with nonsurgical ablation regimens. In addition to better thermal effect on tumor ablation, nanoparticles can deliver anticancer therapeutics that show synergistic anti-tumor effect in the presence of heat and can also be imaged to achieve precision in therapy. Understanding the molecular mechanism of nanoparticle-mediated tumor ablation could further help engineer nanoparticles of appropriate composition and properties to synergize the ablation effect. This review aims to explore the various types of nonsurgical tumor ablation methods currently used in cancer treatment and potential improvements by nanotechnology applications. PMID:20866097

  14. Dissolution on Titan and on Earth: Towards the age of Titan's karstic landscapes

    NASA Astrophysics Data System (ADS)

    Cornet, T.; Cordier, D.; Le Bahers, T.; Bourgeois, O.; Fleurant, C.; Le Mouélic, S.; Altobelli, N.

    2015-10-01

    The morphology of Titan's lacustrine depressions led to comparisons with terrestrial depressions developed by karstic dissolution. We tested this hypothesis by computing dissolution rates of Titan's solids in liquid methane. We inferred from these rates the timescales needed to create dissolution landforms of a given depth. Dissolution would be a very efficient geological process to shape Titan's surface, on timescales generally shorter than 100 Myrs, consistent with the youth of Titan's surface (<1 Gyr).

  15. Nitrogen Chemistry in Titan's Upper Atmosphere

    NASA Technical Reports Server (NTRS)

    McKay, Christopher P.; Cuzzi, Jeffrey (Technical Monitor)

    1996-01-01

    In Titan's upper atmosphere N2 is dissociated to N by solar UV and high energy electrons. This flux of N provides for interesting organic chemistry in the lower atmosphere of Titan. Previously the main pathway for the loss of this N was thought to be the formation of HCN, followed by diffusion of this HCN to lower altitudes leading ultimately to condensation. However, recent laboratory simulations of organic chemistry in Titan's atmosphere suggest that formation of the organic haze may be an important sink for atmospheric N. Because estimates of the eddy diffusion profile on Titan have been based on the HCN profile, inclusion of this additional sink for N will affect estimates for all transport processes in Titan's atmosphere. This and other implications of this sink for the N balance on Titan are considered.

  16. Photochemically driven collapse of Titan's atmosphere.

    PubMed

    Lorenz, R D; McKay, C P; Lunine, J I

    1997-01-31

    Saturn's giant moon Titan has a thick (1.5 bar) nitrogen atmosphere, which has a temperature structure that is controlled by the absorption of solar and thermal radiation by methane, hydrogen, and organic aerosols into which methane is irreversibly converted by photolysis. Previous studies of Titan's climate evolution have been done with the assumption that the methane abundance was maintained against photolytic depletion throughout Titan's history, either by continuous supply from the interior or by buffering by a surface or near surface reservoir. Radiative-convective and radiative-saturated equilibrium models of Titan's atmosphere show that methane depletion may have allowed Titan's atmosphere to cool so that nitrogen, its main constituent, condenses onto the surface, collapsing Titan into a Triton-like frozen state with a thin atmosphere. PMID:9005844

  17. Navigation Systems for Ablation

    PubMed Central

    Wood, B. J.; Kruecker, J.; Abi-Jaoudeh, N; Locklin, J.; Levy, E.; Xu, S.; Solbiati, L.; Kapoor, A.; Amalou, H.; Venkatesan, A.

    2010-01-01

    Navigation systems, devices and intra-procedural software are changing the way we practice interventional oncology. Prior to the development of precision navigation tools integrated with imaging systems, thermal ablation of hard-to-image lesions was highly dependent upon operator experience, spatial skills, and estimation of positron emission tomography-avid or arterial-phase targets. Numerous navigation systems for ablation bring the opportunity for standardization and accuracy that extends our ability to use imaging feedback during procedures. Existing systems and techniques are reviewed, and specific clinical applications for ablation are discussed to better define how these novel technologies address specific clinical needs, and fit into clinical practice. PMID:20656236

  18. The magnetic memory of Titan's ionized atmosphere.

    PubMed

    Bertucci, C; Achilleos, N; Dougherty, M K; Modolo, R; Coates, A J; Szego, K; Masters, A; Ma, Y; Neubauer, F M; Garnier, P; Wahlund, J-E; Young, D T

    2008-09-12

    After 3 years and 31 close flybys of Titan by the Cassini Orbiter, Titan was finally observed in the shocked solar wind, outside of Saturn's magnetosphere. These observations revealed that Titan's flow-induced magnetosphere was populated by "fossil" fields originating from Saturn, to which the satellite was exposed before its excursion through the magnetopause. In addition, strong magnetic shear observed at the edge of Titan's induced magnetosphere suggests that reconnection may have been involved in the replacement of the fossil fields by the interplanetary magnetic field. PMID:18787164

  19. The Global Energy Balance of Titan

    NASA Technical Reports Server (NTRS)

    Li, Liming; Nixon, Conor A.; Achterberg, Richard K.; Smith, Mark A.; Gorius, Nicolas J. P.; Jiang, Xun; Conrath, Barney J.; Gierasch, Peter J.; Simon-Miller, Amy A.; Flasar, F. Michael; Baines, Kevin H.; Ingersoll, Andrew P.; West, Robert A.; Vasavada, Ashwin R.; Ewald, Shawn P.

    2011-01-01

    We report the first measurement of the global emitted power of Titan. Longterm (2004-2010) observations conducted by the Composite Infrared Spectrometer (CIRS) onboard Cassini reveal that the total emitted power by Titan is (2.84 plus or minus 0.01) x 10(exp 8) watts. Together with previous measurements of the global absorbed solar power of Titan, the CIRS measurements indicate that the global energy budget of Titan is in equilibrium within measurement error. The uncertainty in the absorbed solar energy places an upper limit on the energy imbalance of 5.3%.

  20. Titan In Situ Exploration Concepts at JPL

    NASA Technical Reports Server (NTRS)

    Elliott, John O.; Hall, Jeffery L.; Jones, Jack; Reh, Kim

    2008-01-01

    This slide presentation reviews concepts for exploring Titan via balloon vehicles. The presentation includes information about the baseline options, the deployment scenario, and the balloon technology development.

  1. Can Titan generate tori in Saturn's magnetosphere?

    NASA Astrophysics Data System (ADS)

    Smith, H. T.; Johnson, R. E.; Rymer, A. M.; Mitchell, D. G.

    2011-12-01

    Prior to Cassini's arrival at Saturn, nitrogen ions were thought to dominate heavy plasma in Saturn's magnetosphere and that Titan's atmosphere was the source of this nitrogen. Therefore, the presence of a Titan nitrogen torus was anticipated. However, it is now known water-group ions dominate Saturn's heavy ion plasma. While nitrogen ions have been detected beyond the orbit of Rhea, they appear to be originating from the Enceladus plumes with little nitrogen plasma detected in the magnetosphere near Titan's orbit. These results appear inconsistent with the expectation that Titan's dense relatively unprotected atmosphere should provide a significant source of heavy particles to Saturn's magnetosphere. This inconsistency suggests that the plasma environment at Titan's orbit is much more complex than originally anticipated. In this talk, we expand on our previous research that categorizes the plasma environments near Titan to include all locations along Titan's orbit. Using these categories, we develop characteristic plasma spectra of each type of environment and use these results in a 3D Monte Carlo model to more accurately examine fate of nitrogen and methane escaping Titan's atmosphere. These results are compared to Cassini observations to determine if Titan is capable of generating tori.

  2. The magnetic memory of Titan's ionized atmosphere.

    PubMed

    Bertucci, C; Achilleos, N; Dougherty, M K; Modolo, R; Coates, A J; Szego, K; Masters, A; Ma, Y; Neubauer, F M; Garnier, P; Wahlund, J-E; Young, D T

    2008-09-12

    After 3 years and 31 close flybys of Titan by the Cassini Orbiter, Titan was finally observed in the shocked solar wind, outside of Saturn's magnetosphere. These observations revealed that Titan's flow-induced magnetosphere was populated by "fossil" fields originating from Saturn, to which the satellite was exposed before its excursion through the magnetopause. In addition, strong magnetic shear observed at the edge of Titan's induced magnetosphere suggests that reconnection may have been involved in the replacement of the fossil fields by the interplanetary magnetic field.

  3. Nitrogen fractionation in Titan's aerosols

    NASA Astrophysics Data System (ADS)

    Carrasco, Nathalie; Kuga, Maia; Marty, Bernard; Fleury, Benjamin; Marrocchi, Yves

    2016-06-01

    A strong nitrogen fractionation is found by Cassini in Titan's atmosphere with the detection of 15N-rich HCN relative to N2. Photodissociation of N2 associated or not to self-shielding might involve 15N-rich radicals prone to incorporation into forming organics. However the isotopic composition is only available for very simple gaseous N-bearing compounds, and the propagation and conservation of such a large N-isotopic fractionation upon polymerization is actually out of reach with the instruments onboard Cassini. We will therefore present a first laboratory investigation of the possible enrichment in the solid organic aerosols. We will also discuss the space instrumention required in the future to answer this pending issue on Titan.

  4. Ion Cyclotron Waves at Titan

    NASA Astrophysics Data System (ADS)

    Russell, C. T.; Wei, H.; Cowee, M.; Neubauer, F. M.; Dougherty, M. K.

    2014-12-01

    The observation of ion cyclotron waves was generally expected well before Cassini arrived at Titan in 2004, because strong ion cyclotron waves were seen at Io where its atmosphere interacted with the corotating magnetospheric plasma. However, the region of the interaction of the Saturnian magnetospheric plasma with the Titan atmosphere has been quite devoid of ion cyclotron waves. Finally, on pass T63, ion cyclotron waves were seen briefly. More recently, on pass T98, a longer sequence of ion cyclotron waves also occurred. On pass T63, the pick-up ion signature is that of both H+ and H2+, while on pass T98, only H+ ion cyclotron waves are observed. We examine the strength of these waves and their region of occurrence in the light of our previous work on the expected occurrence of these waves.

  5. Titan's geoid and hydrology: implications for Titan's geological evolution

    NASA Astrophysics Data System (ADS)

    Sotin, Christophe; Seignovert, Benoit; Lawrence, Kenneth; MacKenzie, Shannon; Barnes, Jason; Brown, Robert

    2014-05-01

    A 1x1 degree altitude map of Titan is constructed from the degree 4 gravity potential [1] and Titan's shape [2] determined by the Radio Science measurements and RADAR observations of the Cassini mission. The amplitude of the latitudinal altitude variations is equal to 300 m compared to 600 m for the amplitude of the latitudinal shape variations. The two polar caps form marked depressions with an abrupt change in topography at exactly 60 degrees at both caps. Three models are envisaged to explain the low altitude of the polar caps: (i) thinner ice crust due to higher heat flux at the poles, (ii) fossil shape acquired if Titan had higher spin rate in the past, and (iii) subsidence of the crust following the formation of a denser layer of clathrates as ethane rain reacts with the H2O ice crust [3]. The later model is favored because of the strong correlation between the location of the cloud system during the winter season and the latitude of the abrupt change in altitude. Low altitude polar caps would be the place where liquids would run to and eventually form large seas. Indeed, the large seas of Titan are found at the deepest locations at the North Pole. However, the lakes and terrains considered to be evaporite candidates due to their spectral characteristics in the infrared [4,5] seem to be perched. Lakes may have been filled during Titan's winter and then slowly evaporated leaving material on the surface. Interestingly, the largest evaporite deposits are located at the equator in a deep depression 150 m below the altitude of the northern seas. This observation seems to rule out the presence of a global subsurface hydrocarbon reservoir unless the evaporation rate at the equator is faster than the transport of fluids from the North Pole to the equator. This work has been performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract to NASA. [1] Iess L. et al. (2012) Science, doi 10.1126/science.1219631. [2] Lorenz R.D. (2013

  6. Moldable cork ablation material

    NASA Technical Reports Server (NTRS)

    1977-01-01

    A successful thermal ablative material was manufactured. Moldable cork sheets were tested for density, tensile strength, tensile elongation, thermal conductivity, compression set, and specific heat. A moldable cork sheet, therefore, was established as a realistic product.

  7. Cassini Imaging Results at Titan

    NASA Technical Reports Server (NTRS)

    McEwen, A.; Turtle, E.; Perry J.; Fussner, S.; Porco, C.; West, R.; Johnson, T.; Collins, G.; DelGenio, T.; Barbara, J.

    2005-01-01

    The Cassini Imaging Science Subsystem (ISS) images show striking albedo markings on the surface of Titan. In equatorial regions the albedo patterns have high contrast and exhibit prominent lineaments and linear/angular boundaries suggestive of tectonic influences or fracturing of brittle surficial materials. There are intriguing dark curving lines near the south pole. Here we present several working hypotheses to explain these patterns. We also briefly summarize atmospheric science results.

  8. Safe prescribing: a titanic challenge.

    PubMed

    Routledge, Philip A

    2012-10-01

    The challenge to achieve safe prescribing merits the adjective 'titanic'. The organisational and human errors leading to poor prescribing (e.g. underprescribing, overprescribing, misprescribing or medication errors) have parallels in the organisational and human errors that led to the loss of the Titanic 100 years ago this year. Prescribing can be adversely affected by communication failures, critical conditions, complacency, corner cutting, callowness and a lack of courage of conviction, all of which were also factors leading to the Titanic tragedy. These issues need to be addressed by a commitment to excellence, the final component of the 'Seven C's'. Optimal prescribing is dependent upon close communication and collaborative working between highly trained health professionals, whose role is to ensure maximum clinical effectiveness, whilst also protecting their patients from avoidable harm. Since humans are prone to error, and the environments in which they work are imperfect, it is not surprising that medication errors are common, occurring more often during the prescribing stage than during dispensing or administration. A commitment to excellence in prescribing includes a continued focus on lifelong learning (including interprofessional learning) in pharmacology and therapeutics. This should be accompanied by improvements in the clinical working environment of prescribers, and the encouragement of a strong safety culture (including reporting of adverse incidents as well as suspected adverse drug reactions whenever appropriate). Finally, members of the clinical team must be prepared to challenge each other, when necessary, to ensure that prescribing combines the highest likelihood of benefit with the lowest potential for harm.

  9. Laser ablation of concrete.

    SciTech Connect

    Savina, M.

    1998-10-05

    Laser ablation is effective both as an analytical tool and as a means of removing surface coatings. The elemental composition of surfaces can be determined by either mass spectrometry or atomic emission spectroscopy of the atomized effluent. Paint can be removed from aircraft without damage to the underlying aluminum substrate, and environmentally damaged buildings and sculptures can be restored by ablating away deposited grime. A recent application of laser ablation is the removal of radioactive contaminants from the surface and near-surface regions of concrete. We present the results of ablation tests on concrete samples using a high power pulsed Nd:YAG laser with fiber optic beam delivery. The laser-surface interaction was studied on various model systems consisting of Type I Portland cement with varying amounts of either fine silica or sand in an effort to understand the effect of substrate composition on ablation rates and mechanisms. A sample of non-contaminated concrete from a nuclear power plant was also studied. In addition, cement and concrete samples were doped with non-radioactive isotopes of elements representative of cooling waterspills, such as cesium and strontium, and analyzed by laser-resorption mass spectrometry to determine the contamination pathways. These samples were also ablated at high power to determine the efficiency with which surface contaminants are removed and captured. The results show that the neat cement matrix melts and vaporizes when little or no sand or aggregate is present. Surface flows of liquid material are readily apparent on the ablated surface and the captured aerosol takes the form of glassy beads up to a few tens of microns in diameter. The presence of sand and aggregate particles causes the material to disaggregate on ablation, with intact particles on the millimeter size scale leaving the surface. Laser resorption mass spectrometric analysis showed that cesium and potassium have similar chemical environments in the

  10. Condensation of trace species to form ice layers in Titan's stratosphere

    NASA Astrophysics Data System (ADS)

    Barth, Erika L.

    2015-11-01

    In addition to the organic haze particles produced photochemically in Titan's upper atmosphere, a number of trace gases are also created. These hydrocarbon and nitrile species include C2H6, C2H2, C4H10, HCN, HC3N, C2H5CN and many more. While both Voyager and Cassini observations have found evidence for ices (e.g. C4N2, HCN) in the atmosphere above Titan's poles, these species are also likely to condense at other latitudes forming optically thin ice layers in the stratosphere. A series of simulations have been conducted using Titan CARMA, a 1-D microphysics and radiative transfer model, to explore cloud particle formation with ~20 of Titan's trace hydrocarbon and nitrile gases. These species reach their condensation temperatures between 60 and 110 km. Most condense solely as ices, however, C3H8 will condense first near 70 km as a liquid and then freeze as the droplets descend toward the surface. C3H8 and C2H6 join CH4 as a liquid at Titan's surface. Many ices have long condensation timescales resulting in particle radii ~1 μm or less. Several (including HCN, C3H8, C2H2) will grow 10-50 times larger. Expected condensation altitudes and particle sizes will be presented, as well as the implications for the optical properties of Titan's stratospheric aerosol particles.This work was supported by the NASA Outer Planets Research program.

  11. Safety evaluation of RTG launches aboard Titan IV launch vehicles

    SciTech Connect

    Rosko, Robert J.; Loughin, Stephen

    1997-01-10

    The analytical tool used to evaluate accidents aboard a Titan IV launch vehicle involving a Radioisotope Thermoelectric Generator (RTG) is discussed. The Launch Accident Scenario Evaluation Program-Titan IV version (LASEP-T) uses a Monte Carlo approach to determine the response of an RTG to various threatening environments. The threatening environments arise from a complex interplay of probabilistic and deterministic processes, and are therefore parameterized by a set of random variables with probability distributions. The assessment of the RTG response to a given environment is based on both empirical data and theoretical modeling. Imbedding detailed, complex response models into the LASEP-T calculation was not practical. Simpler response models have been constructed to capture both the inherent variability due to the phenomenology of the accident scenario along with the uncertainty of predicting response behavior. The treatment of variability and uncertainty as it pertains to the launch accident evaluation of RTG response will be discussed.

  12. Performance of Conformable Ablators in Aerothermal Environments

    NASA Technical Reports Server (NTRS)

    Thornton, J.; Fan, W.; Skokova, K.; Stackpoole, M.; Beck, R.; Chavez-Garcia, J.

    2012-01-01

    Conformable Phenolic Impregnated Carbon Ablator, a cousin of Phenolic Impregnated Carbon Ablator (PICA), was developed at NASA Ames Research Center as a lightweight thermal protection system under the Fundamental Aeronautics Program. PICA is made using a brittle carbon substrate, which has a very low strain to failure. Conformable PICA is made using a flexible carbon substrate, a felt in this case. The flexible felt significantly increases the strain to failure of the ablator. PICA is limited by its thermal mechanical properties. Future NASA missions will require heatshields that are more fracture resistant than PICA and, as a result, NASA Ames is working to improve PICAs performance by developing conformable PICA to meet these needs. Research efforts include tailoring the chemistry of conformable PICA with varying amounts of additives to enhance mechanical properties and testing them in aerothermal environments. This poster shows the performance of conformable PICA variants in arc jets tests. Some mechanical and thermal properties will also be presented.

  13. [Steam ablation of varicose veins].

    PubMed

    van den Bos, Renate R; Malskat, Wendy S J; Neumann, H A M Martino

    2013-01-01

    In many western countries endovenous thermal ablation techniques have largely replaced classical surgery for the treatment of saphenous varicose veins as they are more effective and patient friendly. Because these treatments can be performed under local tumescent anaesthesia, patients can mobilize immediately after the procedure. A new method of thermal ablation is endovenous steam ablation, which is a fast and easy procedure. Steam ablation may cause less pain than laser ablation and it is also cheaper and more flexible than segmental radiofrequency ablation. PMID:23484513

  14. Ablative therapies for renal tumors

    PubMed Central

    Ramanathan, Rajan; Leveillee, Raymond J.

    2010-01-01

    Owing to an increased use of diagnostic imaging for evaluating patients with other abdominal conditions, incidentally discovered kidney masses now account for a majority of renal tumors. Renal ablative therapy is assuming a more important role in patients with borderline renal impairment. Renal ablation uses heat or cold to bring about cell death. Radiofrequency ablation and cryoablation are two such procedures, and 5-year results are now emerging from both modalities. Renal biopsy at the time of ablation is extremely important in order to establish tissue diagnosis. Real-time temperature monitoring at the time of radiofrequency ablation is very useful to ensure adequacy of ablation. PMID:21789083

  15. Titania bound sodium titanate ion exchanger

    DOEpatents

    DeFilippi, Irene C. G.; Yates, Stephen Frederic; Shen, Jian-Kun; Gaita, Romulus; Sedath, Robert Henry; Seminara, Gary Joseph; Straszewski, Michael Peter; Anderson, David Joseph

    1999-03-23

    This invention is method for preparing a titania bound ion exchange composition comprising admixing crystalline sodium titanate and a hydrolyzable titanium compound and, thereafter drying the titania bound crystalline sodium titanate and subjecting the dried titania bound ion exchange composition to optional compaction and calcination steps to improve the physical strength of the titania bound composition.

  16. Nitrogen Ocean/Lakes on Early Titan

    NASA Astrophysics Data System (ADS)

    Toon, Owen B.; Tian, F.; McKay, C.; Moore, J. M.; Zahnle, K.; Howard, A. D.

    2010-10-01

    Today Titan's surface temperature is 95 K and its atmosphere contains 1.5 bars of N2. The standard model for Titan is that the current thick atmosphere has been present over the age of the Solar System. However, observations of Titan present some paradoxes for the standard model: the short life time of methane, the lack of good evidence for active cryovolcanism, and the inadequate surface deposit to account for the photochemical products that would have accumulated over 4.5 billion years. Thus alternative models are motivated. Today both surface albedo and greenhouse warming contribute to Titan's surface temperature and its atmosphere condition. The albedo could have been different if the surface of ancient Titan was covered by liquid nitrogen/methane or solid methane ice. The greenhouse effect depends on the existence of atmospheric methane and nitrogen. The variations of either factor could have made ancient Titan similar to present Triton with high surface albedo and little atmosphere. Alternatively early Titan could have had much larger fraction of its nitrogen and methane in liquid phase (ocean/lakes), which would have interesting geological implications. In this work we will explore the effect of changing surface albedo, surface reservoirs of nitrogen and methane, and greenhouse warming on ancient Titan's climate.

  17. Activity and stability studies of titanates and titanate-carbon nanotubes supported Ag anode catalysts for direct methanol fuel cell

    NASA Astrophysics Data System (ADS)

    Mohamed, Mohamed Mokhtar; Khairy, M.; Eid, Salah

    2016-02-01

    Titanate-SWCNT; synthesized via exploiting the interaction between TiO2 anatase with oxygen functionalized SWCNT, supported Ag nanoparticles and Ag/titanate are characterized using XRD, TEM-EDX-SAED, N2 adsorption, Photoluminescence, Raman and FTIR spectroscopy. These samples are tested for methanol electrooxidation via using cyclic voltammetry (CV) and impedance measurements. It is shown that Ag/titanate nanotubes exhibited superior electrocatalytic performance for methanol oxidation (4.2 mA cm-2) than titanate-SWCNT, Ag/titanate-SWCNT and titanate. This study reveals the existence of a strong metal-support interaction in Ag/titanate as explored via formation of Ti-O-Ag bond at 896 cm-1 and increasing surface area and pore volume (103 m2 g-1, 0.21 cm3 g-1) compared to Ag/titanate-SWCNT (71 m2 g-1, 0.175 cm3 g-1) that suffers perturbation and defects following incorporation of SWCNT and Ag. Embedding Ag preferably in SWCNT rather than titanate in Ag/titanate-SWCNT disturbs the electron transfer compared to Ag/titanate. Charge transfer resistance depicted from Nyquist impedance plots is found in the order of titanate > Ag/titanate-SWCNT > titanate-SWCNT > Ag/titanate. Accordingly, Ag/titanate indicates a slower current degradation over time compared to rest of catalysts. Conductivity measurements indicate that it follows the order Ag/titanate > Ag/titanate-SWCNT > titanate > titanate-SWCNT declaring that SWCNT affects seriously the conductivity of Ag(titanate) due to perturbations caused in titanate and sinking of electrons committed by Ago through SWCNT.

  18. Size and shape of Saturn's moon Titan.

    PubMed

    Zebker, Howard A; Stiles, Bryan; Hensley, Scott; Lorenz, Ralph; Kirk, Randolph L; Lunine, Jonathan

    2009-05-15

    Cassini observations show that Saturn's moon Titan is slightly oblate. A fourth-order spherical harmonic expansion yields north polar, south polar, and mean equatorial radii of 2574.32 +/- 0.05 kilometers (km), 2574.36 +/- 0.03 km, and 2574.91 +/- 0.11 km, respectively; its mean radius is 2574.73 +/- 0.09 km. Titan's shape approximates a hydrostatic, synchronously rotating triaxial ellipsoid but is best fit by such a body orbiting closer to Saturn than Titan presently does. Titan's lack of high relief implies that most--but not all--of the surface features observed with the Cassini imaging subsystem and synthetic aperture radar are uncorrelated with topography and elevation. Titan's depressed polar radii suggest that a constant geopotential hydrocarbon table could explain the confinement of the hydrocarbon lakes to high latitudes.

  19. Interaction of Titan's ionosphere with Saturn's magnetosphere.

    PubMed

    Coates, Andrew J

    2009-02-28

    Titan is the only Moon in the Solar System with a significant permanent atmosphere. Within this nitrogen-methane atmosphere, an ionosphere forms. Titan has no significant magnetic dipole moment, and is usually located inside Saturn's magnetosphere. Atmospheric particles are ionized both by sunlight and by particles from Saturn's magnetosphere, mainly electrons, which reach the top of the atmosphere. So far, the Cassini spacecraft has made over 45 close flybys of Titan, allowing measurements in the ionosphere and the surrounding magnetosphere under different conditions. Here we review how Titan's ionosphere and Saturn's magnetosphere interact, using measurements from Cassini low-energy particle detectors. In particular, we discuss ionization processes and ionospheric photoelectrons, including their effect on ion escape from the ionosphere. We also discuss one of the unexpected discoveries in Titan's ionosphere, the existence of extremely heavy negative ions up to 10000amu at 950km altitude. PMID:19073464

  20. The Lakes and Seas of Titan

    NASA Astrophysics Data System (ADS)

    Hayes, Alexander G.

    2016-06-01

    Analogous to Earth's water cycle, Titan's methane-based hydrologic cycle supports standing bodies of liquid and drives processes that result in common morphologic features including dunes, channels, lakes, and seas. Like lakes on Earth and early Mars, Titan's lakes and seas preserve a record of its climate and surface evolution. Unlike on Earth, the volume of liquid exposed on Titan's surface is only a small fraction of the atmospheric reservoir. The volume and bulk composition of the seas can constrain the age and nature of atmospheric methane, as well as its interaction with surface reservoirs. Similarly, the morphology of lacustrine basins chronicles the history of the polar landscape over multiple temporal and spatial scales. The distribution of trace species, such as noble gases and higher-order hydrocarbons and nitriles, can address Titan's origin and the potential for both prebiotic and biotic processes. Accordingly, Titan's lakes and seas represent a compelling target for exploration.

  1. Size and shape of Saturn's moon Titan

    USGS Publications Warehouse

    Zebker, Howard A.; Stiles, Bryan; Hensley, Scott; Lorenz, Ralph; Kirk, Randolph L.; Lunine, Jonathan

    2009-01-01

    Cassini observations show that Saturn's moon Titan is slightly oblate. A fourth-order spherical harmonic expansion yields north polar, south polar, and mean equatorial radii of 2574.32 ± 0.05 kilometers (km), 2574.36 ± 0.03 km, and 2574.91 ± 0.11 km, respectively; its mean radius is 2574.73 ± 0.09 km. Titan's shape approximates a hydrostatic, synchronously rotating triaxial ellipsoid but is best fit by such a body orbiting closer to Saturn than Titan presently does. Titan's lack of high relief implies that most—but not all—of the surface features observed with the Cassini imaging subsystem and synthetic aperture radar are uncorrelated with topography and elevation. Titan's depressed polar radii suggest that a constant geopotential hydrocarbon table could explain the confinement of the hydrocarbon lakes to high latitudes.

  2. Interaction of Titan's ionosphere with Saturn's magnetosphere.

    PubMed

    Coates, Andrew J

    2009-02-28

    Titan is the only Moon in the Solar System with a significant permanent atmosphere. Within this nitrogen-methane atmosphere, an ionosphere forms. Titan has no significant magnetic dipole moment, and is usually located inside Saturn's magnetosphere. Atmospheric particles are ionized both by sunlight and by particles from Saturn's magnetosphere, mainly electrons, which reach the top of the atmosphere. So far, the Cassini spacecraft has made over 45 close flybys of Titan, allowing measurements in the ionosphere and the surrounding magnetosphere under different conditions. Here we review how Titan's ionosphere and Saturn's magnetosphere interact, using measurements from Cassini low-energy particle detectors. In particular, we discuss ionization processes and ionospheric photoelectrons, including their effect on ion escape from the ionosphere. We also discuss one of the unexpected discoveries in Titan's ionosphere, the existence of extremely heavy negative ions up to 10000amu at 950km altitude.

  3. Radioactive Transfer Models for Saturn and Titan

    NASA Technical Reports Server (NTRS)

    Wu, S. T.

    1996-01-01

    The infrared spectra of the earth's atmosphere and planetary atmospheres contains information about atmospheric physical and chemical processes. Atmospheric molecular constituents absorb and emit infrared radiation by rotational and vibrational transition. Observed spectra exhibit characteristic features in the electromagnetic spectrum region. Observation of the absorption or thermal emission spectra may be obtained with space-borne high resolution infrared spectrometers in the 10-5000 cm(exp -1) (2-1000 micro-m) spectral region. Information about the atmospheric thermal structure, composition, and the chemical and physical processes of the observed spectral was accomplished. A preliminary version of a P-T retrieval algorithm for Saturn using all three modes for temperature inversion, e.g., CH4-limb, and H2-nadir spectra was completed and tested for accuracy. Radiative transfer and inversion programs were studied and analyzed for applications to infrared limb thermal emission observations of Saturn and Titan from the Cassini Orbiter, as well as Earth's atmosphere. Analysis and modification of the existing radiative transfer and inversion programs for Earth and planetary atmospheres are being made. Data analysis and retrieval of information form the observations by digital calculations were carried out at UAH and MSFC computer. The working program for generating and reading g-k arrays for using the c-k arrays via the c-k method for radiative transfer calculations for desired atmospheric and instrumental parameters was completed, tested for accuracy and resides at the MSFC computer.

  4. Titan Orbiter with Aerorover Mission (TOAM)

    NASA Technical Reports Server (NTRS)

    Sittler, E. C., Jr.; Cooper, J. F.; Mahaffy, P.; Esper, J.; Fairbrother, D.; Farley, R.; Pitman, J.; Kojiro, D. R.; Acuna, M.; Allen, M.; Bjoraker, G.; Brasunas, J.; Farrell, W.; Burchell, M. J.; Burger, M.; Chin, G.; Coates, A. J.; Farrell, W.; Flasar, M.; Gerlach, B.; Gorevan, S.; Hartle, R. E.; Im, Eastwood; Jennings, D.; Johnson, R. E.

    2007-01-01

    We propose to develop a new mission to Titan called Titan Orbiter with Aerorover Mission (TOAM). This mission is motivated by the recent discoveries of Titan, its atmosphere and its surface by the Huygens Probe, and a combination of in situ, remote sensing and radar mapping measurements of Titan by the Cassini orbiter. Titan is a body for which Astrobiology (i.e., prebiotic chemistry) will be the primary science goal of any future missions to it. TOAM is planned to use an orbiter and balloon technology (i.e., aerorover). Aerobraking will be used to put payload into orbit around Titan. One could also use aerobraking to put spacecraft into orbit around Saturn first for an Enceladus phase of the mission and then later use aerocapture to put spacecraft into orbit around Titan. The Aerorover will probably use a hot air balloon concept using the waste heat from the MMRTG approx. 1000 watts. Orbiter support for the Aerorover is unique to our approach for Titan. Our strategy to use an orbiter is contrary to some studies using just a single probe with balloon. Autonomous operation and navigation of the Aerorover around Titan will be required, which will include descent near to the surface to collect surface samples for analysis (i.e., touch and go technique). The orbiter can provide both relay station and GPS roles for the Aerorover. The Aerorover will have all the instruments needed to sample Titan's atmosphere, surface, possible methane lakes-rivers, use multi-spectral imagers for surface reconnaissance; to take close up surface images; take core samples and deploy seismometers during landing phase. Both active and passive broadband remote sensing techniques will be used for surface topography, winds and composition measurements.

  5. Processing science of barium titanate

    NASA Astrophysics Data System (ADS)

    Aygun, Seymen Murat

    Barium titanate and barium strontium titanate thin films were deposited on base metal foils via chemical solution deposition and radio frequency magnetron sputtering. The films were processed at elevated temperatures for densification and crystallization. Two unifying research goals underpin all experiments: (1) To improve our fundamental understanding of complex oxide processing science, and (2) to translate those improvements into materials with superior structural and electrical properties. The relationships linking dielectric response, grain size, and thermal budget for sputtered barium strontium titanate were illustrated. (Ba 0.6Sr0.4)TiO3 films were sputtered on nickel foils at temperatures ranging between 100-400°C. After the top electrode deposition, the films were co-fired at 900°C for densification and crystallization. The dielectric properties were observed to improve with increasing sputter temperature reaching a permittivity of 1800, a tunability of 10:1, and a loss tangent of less than 0.015 for the sample sputtered at 400°C. The data can be understood using a brick wall model incorporating a high permittivity grain interior with low permittivity grain boundary. However, this high permittivity value was achieved at a grain size of 80 nm, which is typically associated with strong suppression of the dielectric response. These results clearly show that conventional models that parameterize permittivity with crystal diameter or film thickness alone are insufficiently sophisticated. Better models are needed that incorporate the influence of microstructure and crystal structure. This thesis next explores the ability to tune microstructure and properties of chemically solution deposited BaTiO3 thin films by modulation of heat treatment thermal profiles and firing atmosphere composition. Barium titanate films were deposited on copper foils using hybrid-chelate chemistries. An in-situ gas analysis process was developed to probe the organic removal and the

  6. An assessment of the readiness of ablative materials for preflight application to the shuttle orbiter

    NASA Technical Reports Server (NTRS)

    Tompkins, S. S.; Brewer, W. D.; Clark, R. K.; Pittman, C. M.; Brinkley, K. L.

    1980-01-01

    The shuttle orbiter relies primarily on a reusable surface insulation (RSI) thermal protection system (TPS). The RSI is very efficient in its thermal performance; however, the RSI tile system has shown poor mechanical integrity. The state-of-the-art of the ablative TPS is reviewed, and an assessment made of the ablator's readiness for use on the shuttle orbiter. Unresolved technical issues with regard to the ablative TPS are identified. Short time, highly focused analytical and experimental programs were initiated to: (1) identify candidate ablation materials; (2) assess the data base for these materials; (3) evaluate the need and kind of waterproof coating; (4) calculate thermal and other stresses in an ablator tile; (5) identify an acceptable ablator/RSI tile joint filler; and (6) assess the sensitivity of the ablator to sequential heat pulses. Results from some of these programs are discussed.

  7. The detached haze layer in Titan's mesosphere: The formation process

    NASA Astrophysics Data System (ADS)

    Lavvas, P.; Yelle, R. V.; Vuitton, V.

    2008-09-01

    Cassini observations made by the Imaging Science Subsystem (ISS) [1] and by the UltraViolet Imaging Spectrometer (UVIS) [2,3] have revealed the presence of a detached haze layer in Titan's mesosphere at an altitude of 520 km. Analysis of the observed optical properties presented in the accompanying talk [5], suggests that the average size of particles in the detached layer is of ~40 nm, with an imaginary index k < 0.3 at 187.5 nm and a number density of ˜30 particles cm-3, while calculations of the sedimentation velocity of the haze particles coupled with the derived number density imply a mass flux of 1.9-3.2 × 10-14 g cm-2 s-1. This is approximately equal to the mass flux required to explain the main haze layer and suggests that the main haze layer in Titan's stratosphere is formed primarily by sedimentation and coagulation of particles in the detached layer [5,6]. The HASI data clearly show that the haze is coincident with a temperature maximum. This rules out condensation as the source of the detached haze. We have also considered a more complicated scenario in which the detached layer is caused by an increase in the density of condensation nuclei near 520 km. This is motivated by the fact that silicate micrometeorites ablate near 500 km [7,8]. Recondensation of the refractory vapor creates `smoke' particles that could serve as condensation nuclei. Combination of Pioneer measurements along with theoretical estimations for the particles velocity distribution, suggest a mass flux of ~10-17 g cm-2 s-1 at Saturn's region [9], while measurements from the Cassini Dust Analyser (CDA) suggest a similar magnitude at Titan's location [10]. These fluxes are ~3 orders of magnitude smaller than the lower limit of the estimated mass flux out of the detached haze layer, so meteorite ablation can not be the direct cause of the aerosol layer. However, if the ablated meteoritic material reforms 1 nm particles, the implied number flux would be 2.4 × 103 particles cm-2 s-1

  8. Spectral Characteristics of Titan's Surface

    NASA Astrophysics Data System (ADS)

    Griffith, Caitlin A.; Turner, Jake D.; Penteado, Paulo; Khamsi, Tymon B.; Soderblom, Jason M.

    2014-11-01

    Cassini/Huygens and ground-based measurements of Titan reveal an eroded surface, with lakes, dunes, and sinuous washes. These features, coupled with measurements of clouds and rain, indicate the transfer of methane between Titan’s surface and atmosphere. The presence of methane-damp lowlands suggests further that the atmospheric methane (which is continually depleted through photolysis) may be supplied by sub-surface reservoirs. The byproducts of methane photolysis condense onto the surface, leaving layers of organic sediments that record Titan’s past atmospheres.Thus knowledge of the source and history of Titan's atmosphere requires measurements of the large scale compositional makeup of Titan's surface, which is shrouded by a thick and hazy atmosphere. Towards this goal, we analyzed roughly 100,000 spectra recorded by Cassini’s Visual and Infrared Mapping Spectrometer (VIMS). Our study is confined to the latitude region (20S—20N) surrounding the landing site of the Huygens probe (at 10S, 192W), which supplied only measurement of the vertical profiles of the methane abundance and haze scattering characteristics. VIMS near-IR spectral images indicate subtle latitudinal and temporal variations in the haze characteristics in the tropics. We constrain these small changes with full radiative transfer analyses of each of the thousands of VIMS spectra, which were recorded of different terrains and at different lighting conditions. The resulting models of Titan’s atmosphere as a function of latitude and year indicate the seasonal migration of Titan’s tropical haze and enable the derivation of Titan’s surface albedo at 8 near-IR wavelength regions where Titan’s atmosphere is transparent enough to allow visibility to the surface. The resultant maps of Titan’s surface indicate a number of terrain types with distinct spectral characteristics that are suggestive of atmospheric and surficial processes, including the deposition of organic material, erosion of

  9. The energetics of Titan's ionosphere

    NASA Astrophysics Data System (ADS)

    Roboz, A.; Nagy, A. F.

    1994-02-01

    We have developed a comprehensive model to study the dynamics and energetics of the ionosphere of Titan. We solved the one-dimensional, time-dependent, coupled continuity and momentum equations for several ion species, together with single ion and electron energy equations, in order to calculate density, velocity, and temperature profiles. Calculations were carried out for several cases corresponding to different local times and configurations of the Titan-Saturn system. In our model the effects of horizontal magnetic fields were assumed to be negligible, except for their effect on reducing the electron and ion thermal conductivities and inhibiting vertical transport in the subram region. The ionospheric density peak was found to be at an altitude of about 1100 km, in accordance with earlier model calculations. The ionosphere is chemically controlled below an altitude of about 1500 km. Above this level, ion densities differ significantly from their chemical equilibrium values due to strong upward ion velocities. Heat is deposited in a narrow region around the ionospheric peak, resulting in temperature profiles increasing sharply and reaching nearly constant values of 800-1000 deg K for electrons and 300 deg K for ions in the topside, assuming conditions appropriate for the wake region. In the subram region magnetic correction factors make the electron heat conductivities negligible, resulting in electron temperatures increasing strongly with altitude and reaching values in the order of 5000 deg K at our upper boundary located at 2200 km. Ion chemical heating is found to play an important role in shaping the ion energy balance in Titan's ionosphere.

  10. Hydrogen diffusion in lead zirconate titanate and barium titanate

    NASA Astrophysics Data System (ADS)

    Alvine, K. J.; Vijayakumar, M.; Bowden, M. E.; Schemer-Kohrn, A. L.; Pitman, S. G.

    2012-08-01

    Hydrogen is a potential clean-burning, next-generation fuel for vehicle and stationary power. Unfortunately, hydrogen is also well known to have serious materials compatibility issues in metals, polymers, and ceramics. Piezoelectric actuator materials proposed for low-cost, high efficiency high-pressure hydrogen internal combustion engines (HICE) are known to degrade rapidly in hydrogen. This limits their potential use and poses challenges for HICE. Hydrogen-induced degradation of piezoelectrics is also an issue for low-pressure hydrogen passivation in ferroelectric random access memory. Currently, there is a lack of data in the literature on hydrogen species diffusion in piezoelectrics in the temperature range appropriate for the HICE as charged via a gaseous route. We present 1HNMR quantification of the local hydrogen species diffusion within lead zirconate titanate and barium titanate on samples charged by exposure to high-pressure gaseous hydrogen ˜32 MPa. Results are discussed in context of theoretically predicted interstitial hydrogen lattice sites and aqueous charging experiments from existing literature.

  11. Hydrogen diffusion in lead zirconate titanate and barium titanate

    SciTech Connect

    Alvine, K. J.; Vijayakumar, M.; Bowden, M. E.; Schemer-Kohrn, A. L.; Pitman, S. G.

    2012-08-28

    Hydrogen is a potential clean-burning, next-generation fuel for vehicle and stationary power. Unfortunately, hydrogen is also well known to have serious materials compatibility issues in metals, polymers, and ceramics. Piezoelectric actuator materials proposed for low-cost, high efficiency high-pressure hydrogen internal combustion engines (HICE) are known to degrade rapidly in hydrogen. This limits their potential use and poses challenges for HICE. Hydrogen-induced degradation of piezoelectrics is also an issue for low-pressure hydrogen passivation in ferroelectric random access memory. Currently, there is a lack of data in the literature on hydrogen species diffusion in piezoelectrics in the temperature range appropriate for the HICE as charged via a gaseous route. We present 1HNMR quantification of the local hydrogen species diffusion within lead zirconate titanate and barium titanate on samples charged by exposure to high-pressure gaseous hydrogen ~32 MPa. We discuss results in the context of theoretically predicted interstitial hydrogen lattice sites and aqueous charging experiments from existing literature.

  12. Aerosol growth in Titan's ionosphere.

    PubMed

    Lavvas, Panayotis; Yelle, Roger V; Koskinen, Tommi; Bazin, Axel; Vuitton, Véronique; Vigren, Erik; Galand, Marina; Wellbrock, Anne; Coates, Andrew J; Wahlund, Jan-Erik; Crary, Frank J; Snowden, Darci

    2013-02-19

    Photochemically produced aerosols are common among the atmospheres of our solar system and beyond. Observations and models have shown that photochemical aerosols have direct consequences on atmospheric properties as well as important astrobiological ramifications, but the mechanisms involved in their formation remain unclear. Here we show that the formation of aerosols in Titan's upper atmosphere is directly related to ion processes, and we provide a complete interpretation of observed mass spectra by the Cassini instruments from small to large masses. Because all planetary atmospheres possess ionospheres, we anticipate that the mechanisms identified here will be efficient in other environments as well, modulated by the chemical complexity of each atmosphere. PMID:23382231

  13. Fractal aggregates in Titan's atmosphere

    NASA Astrophysics Data System (ADS)

    Cabane, M.; Rannou, P.; Chassefiere, E.; Israel, G.

    1993-04-01

    The cluster structure of Titan's atmosphere was modeled by using an Eulerian microphysical model with the specific formulation of microphysical laws applying to fractal particles. The growth of aggregates in the settling phase was treated by introducing the fractal dimension as a parameter of the model. The model was used to obtain a vertical distribution of size and number density of the aggregates for different production altitudes. Results confirm previous estimates of the formation altitude of photochemical aerosols. The vertical profile of the effective radius of aggregates was calculated as a function of the visible optical depth.

  14. Condensation in Titan's lower atmosphere

    NASA Astrophysics Data System (ADS)

    Lavvas, P.; Griffith, C. A.; Yelle, R. V.

    2011-10-01

    We present a self-consistent description of Titan's aerosols-clouds-gases system and compare our results with the optical properties retrieved from measurements made by the Descent Imager / Spectral Radiometer (DISR) experiment on the Huygens probe [4]. Our calculations include the condensation of methane, ethane and hydrogen cyanide on photochemical aerosols produced in the thermosphere. Our results suggest that the two distinct extinction layers observed by DISR below 80 km are produced by HCN and methane condensation, respectively, while for the Huygens' equatorial conditions simulated here, the contribution of ethane clouds to the total opacity is negligible

  15. This is Commercial Titan, Inc

    NASA Astrophysics Data System (ADS)

    van Rensselaer, F. L.; Slovikoski, R. D.; Abels, T. C.

    1989-10-01

    Out of a quarter-century heritage of eminently successful expendable launch vehicle history with the U.S government, a commercial launch services enterprise which challenges the corporation as well as the competition has been launched within the Martin Marietta Corporation. This paper is an inside look at the philosophy, structure, and success of the new subsidiary, Commercial Titan, Inc., which is taking on its U.S. and foreign rocket-making competitors to win a share of the international communication satellite market as well as the U.S. government commercial launch services market.

  16. Transient Ablation of Teflon Hemispheres

    NASA Technical Reports Server (NTRS)

    Arai, Norio; Karashima, Kei-ichi; Sato, Kiyoshi

    1997-01-01

    For high-speed entry of space vehicles into atmospheric environments, ablation is a practical method for alleviating severe aerodynamic heating. Several studies have been undertaken on steady or quasi-steady ablation. However, ablation is a very complicated phenomenon in which a nonequilibrium chemical process is associated with an aerodynamic process that involves changes in body shape with time. Therefore, it seems realistic to consider that ablation is an unsteady phenomenon. In the design of an ablative heat-shield system, since the ultimate purpose of the heat shield is to keep the internal temperature of the space vehicle at a safe level during entry, the transient heat conduction characteristics of the ablator may be critical in the selection of the material and its thickness. This note presents an experimental study of transient ablation of Teflon, with particular emphasis on the change in body shape, the instantaneous internal temperature distribution, and the effect of thermal expansion on ablation rate.

  17. Advanced Ablative TPS

    NASA Technical Reports Server (NTRS)

    Gasch, Matthew J.

    2011-01-01

    Early NASA missions (Gemini, Apollo, Mars Viking) employed new ablative TPS that were tailored for the entry environment. After 40 years, heritage ablative TPS materials using Viking or Pathfinder era materials are at or near their performance limits and will be inadequate for future exploration missions. Significant advances in TPS materials technology are needed in order to enable any subsequent human exploration missions beyond Low Earth Orbit. This poster summarizes some recent progress at NASA in developing families of advanced rigid/conformable and flexible ablators that could potentially be used for thermal protection in planetary entry missions. In particular the effort focuses technologies required to land heavy (approx.40 metric ton) masses on Mars to facilitate future exploration plans.

  18. Titan - a New Laboratory for Oceanography

    NASA Astrophysics Data System (ADS)

    Lorenz, R. D.

    2001-12-01

    Saturn's giant moon Titan has a thick (1.5 bar) nitrogen atmosphere, and quite probably large expanses of liquid hydrocarbons on its surface. The physical processes in these lakes and seas will open new vistas on oceanography and limnology. Although the Voyager-era paradigm of a deep, global ocean is ruled out by radar and infrared data showing that at least part of Titan's surface is icy, the photochemical arguments that originally led to the proposal of hydrocarbon oceans still apply. Even if the methane in the atmosphere is being resupplied by delivery from the interior, the ethane produced by photolysis would still accumulate to form large deposits on the surface. The near-infrared maps of Titan's surface from the Hubble Space Telescope and groundbased adaptive optics consistently show a number of dark (in fact, pitch-black!) regions that are strong candidates for hydrocarbon seas. These could be up to some 500km in extent. Titan promises to be a new laboratory for oceanography. Like in meteorology, many ocean processes are better parameterized than they are understood, and thus the different physical circumstances on Titan may shed new light on them. Titan has a lower gravity and its ocean fluids are of lower density, perhaps of lower viscosity (depending on solutes and suspended material) and probably rather more likely to cavitate. The ratio of atmospheric density to ocean density is much larger on Titan than on Earth, suggesting that liquid motions will be well-coupled to surface winds (although the distance from the sun is such that the energy in such winds is likely to be low.) Titan is also subject to strong tidal forces (the equilibrium tide due to Saturn's gravity is some 400x larger than that of the moon on Earth.) Although the 100m tidal bulge stays almost fixed because Titan rotates synchronously, the eccentricity of Titan's orbit leads to significant libration and variation in the tidal strength. The 500km seas allowed by the IR data may yet have a

  19. Spectra and Optical Constants of Nitrile Ices Relevant to Titan

    NASA Astrophysics Data System (ADS)

    Moore, William; Ferrante, R. F.; Hudson, R. L.; Moore, M. H.; Samuelson, R. E.; Anderson, C.

    2009-09-01

    Spectra and optical constants of nitrile ices known or suspected to be in Titan's atmosphere are presented from 2.5 to 200 microns (4000 to 50 cm-1). These results are relevant to the ongoing modeling of Cassini CIRS observations of Titan's winter pole. Ices studied include: HCN, hydrogen cyanide; HC3N, cyanoacetylene; CH3CN, acetonitrile; C2H5CN, propionitrile; C2N2, cyanogen; and C4N2, dicyanoacetylene. For each of these molecules we have calculated optical constants at a variety of temperatures from 15 to at least 95 K for crystalline-phase nitrile ice. Our results are focused on the crystalline ice phase formed after annealing the amorphous nitrile ice condensed at 50 K. In addition, we have recorded spectra for each nitrile deposited near its vaporization temperature and then cooled to 95 K, in search of metastable phases that would be relevant to Titan. This laboratory effort uses a dedicated FTIR spectrometer to record transmission spectra of thin-film ice samples. Laser interference is used to measure film thickness during condensation onto a transparent cold window attached to the tail section of a helium cryostat. Optical constants, real (n) and imaginary (k) refractive indices, are determined using Kramers-Kronig (KK) analysis. Our calculation reproduces the complete spectrum, including all interference effects. Support for this work comes from NASA's Cassini Data Analysis and Planetary Atmospheres Programs

  20. Shuttle subscale ablative nozzle tests

    NASA Technical Reports Server (NTRS)

    Powers, L. B.; Bailey, R. L.

    1980-01-01

    Recent subscale nozzle tests have identified new and promising carbon phenolic nozzle ablatives which utilize staple rayon, PAN, and pitch based carbon cloth. A 4-inch throat diameter submerged test nozzle designed for the 48-inch Jet Propulsion Laboratory char motor was used to evaluate five different designs incorporating 20 candidate ablatives. Test results indicate that several pitch and PAN-based carbon phenolic ablatives can provide erosion and char performance equivalent or superior to the present continuous rayon-based SRM ablative.

  1. Thermochemical Ablation Analysis of the Orion Heatshield

    NASA Technical Reports Server (NTRS)

    Sixel, William

    2015-01-01

    enthalpy and B´c. A MATLAB program was developed to allow for faster, more accurate and automated computation of Arrhenius reaction parameters. These parameters are required for a material model to be used in the CHAR ablation analysis program. This MATLAB program, along with thermogravimetric analysis (TGA) data, was used to generate uncertainties on the Arrhenius parameters for Avcoat. In addition, the TGA fitting program was developed to provide Arrhenius parameters for the ablation model of the gap filler material, RTV silicone.

  2. Thermal ablation in cancer

    PubMed Central

    Liu, Yong; Cao, Cheng-Song; Yu, Yang; Si, Ya-Meng

    2016-01-01

    Radiofrequency ablation (RFA) and cryoablation are alternative forms of therapy used widely in various pathological states, including treatment of carcinogenesis. The reason is that ablation techniques have ability of modulating the immune system. Furthermore, recent studies have applied this form of therapy on tumor microenvironment and in the systematic circulation. Moreover, RFA and cryoablation result in an inflammatory immune response along with tissue disruption. Evidence has demonstrated that these procedures affect carcinogenesis by causing a significant local inflammatory response leading to an immunogenic gene signature. The present review enlightens the current view of these techniques in cancer. PMID:27703520

  3. Transient clouds in Titan's lower atmosphere.

    PubMed

    Griffith, C A; Owen, T; Miller, G A; Geballe, T

    1998-10-01

    The 1980 encounter by the Voyager 1 spacecraft with Titan, Saturn's largest moon, revealed the presence of a thick atmosphere containing nitrogen and methane (1.4 and approximately 0.05 bar, respectively). Methane was found to be nearly saturated at Titan's tropopause, which, with other considerations, led to the hypothesis that Titan might experience a methane analogue of Earth's vigorous hydrological cycle, with clouds, rain and seas. Yet recent analyses of Voyager data indicate large areas of super-saturated methane, more indicative of dry and stagnant conditions. A resolution to this apparent contradiction requires observations of Titan's lower atmosphere, which was hidden from the Voyager cameras by the photochemical haze (or smog) in Titan's stratosphere. Here we report near-infrared spectroscopic observations of Titan within four narrow spectral windows where the moon's atmosphere is ostensibly transparent. We detect pronounced flux enhancements that indicate the presence of reflective methane condensation clouds in the troposphere. These clouds occur at a relatively low altitude (15+/-10 km), at low latitudes, and appear to cover approximately 9 per cent of Titan's disk.

  4. Future Missions to Titan and Enceladus.

    NASA Astrophysics Data System (ADS)

    Beauchamp, Patricia; Reh, Kim; Lunine, Jonathan; Coustenis, Athena; John, Elliott; Matson, Dennis L.; Lebreton, Jean-Pierre; Waite, Hunter; Turtle, Elizabeth

    A mission to Titan is a high priority for exploration, as recommended by the 2003 NRC report on New Frontiers in the Solar System (Decadal Survey). As anticipated by the NRC subcommittee, recent Cassini-Huygens discoveries have revolution-ized our understanding of Titan and its potential for harboring "ingredients" necessary for life. These discoveries reveal that Titan has a thick atmosphere that is rich in organics, possibly contains a vast liquid water subsurface ocean and has energy sources to drive chemical evolu-tion. Furthermore, insight into Titan's climate is important in understanding the climates of Earth, Venus and Mars. With these recent discoveries, interest in Titan as the next scientific target in the outer Solar System is strongly reinforced. Cassini's discovery of active geysers on Enceladus adds a second target in the Saturn system for such a mission, one that is synergistic with Titan in understanding planetary evolution and in adding a potential abode in the Saturn system for life. This presentation will provide an overview of the Titan Saturn System Mission (TSSM) concept, a discussion of other potential concepts, and current plans to advance technical readiness. This work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract to NASA.

  5. Cloud Formation In The Troposphere Of Titan

    NASA Astrophysics Data System (ADS)

    Tsai, I.-Chun; Chen, J.; Liang, M.

    2010-10-01

    Methane-nitrogen containing clouds are known to be present in the troposphere of Titan. However, their formation mechanism and chemical properties remain poorly known. One major difficulty is due to the lack of laboratory constraints, resulting in great uncertainties in modeling cloud formation using microphysical models. Recently CH4-N2 clouds are synthesized in lab under conditions similar to that of Titan, providing a crucial constraint for microphysics model. In this study, a detail microphysical model is developed and used to analyze nucleation and condensation processes occurred in the troposphere of Titan. Sensitivity for the most probable unary and binary nucleation pathways and the subsequent condensation growth of particles is performed based on observed chemical and thermodynamic conditions of Titan's atmosphere. The model is first validated using a laboratory simulation. Comparing to laboratory results, our model simulation shows that binary nucleation from CH4 and N2 produces reasonable particle number concentration as in Titan's atmosphere when appropriate accommodation coefficient for vapor condensation is applied. Applying this detailed model to a model Titan atmosphere, clouds can be formed between 10-30 km, depending on the updraft velocity, with particle sizes of 1-10 μm. These results provide not only information of the size and composition of particles in Titan's atmosphere but also help to design laboratory experiments for measuring critical thermodynamic parameters relevant to the particle production mechanisms, as well as for interpreting observations.

  6. Chemical investigation of Titan and Triton tholins

    NASA Technical Reports Server (NTRS)

    Mcdonald, Gene D.; Thompson, W. R.; Heinrich, Michael; Khare, Bishun N.; Sagan, Carl

    1994-01-01

    We report chromatographic and spectroscopic analyses of both Titan and Triton tholins, organic solids made from the plasma irradiation of 0.9:0.1 and 0.999:0.001 N2/CH4 gas mixtures, respectively. The lower CH4 mixing ratio leads to a nitrogen-richer tholin (N/C greater than 1), probably including nitrogen heterocyclic compounds. Unlike Titan tholin, bulk Triton tholin is poor in nitriles. From high-pressure liquid chromatography, ultraviolet and infrared spectroscopy, and molecular weight estimation by gel filtration chromatography, we conclude that (1) several H2O-soluble fractions, each with distinct UV and IR spectral signatures, are present, (2) these fractions are not identical in the two tholins, (3) the H2O-soluble fractions of Titan tholins do not contain significant amounts of nitriles, despite the major role of nitriles in bulk Titan tholin, and (4) the H2O-soluble fractions of both tholins are mainly molcules containing about 10 to 50 (C + N) atoms. We report yields of amino acids upon hydrolysis of Titan and Triton tholins. Titan tholin is largely insoluble in the putative hydrocarbon lakes or oceans on Titan, but can yield the H2O-soluble species investigated here upon contact with transient (e.g., impact-generated) liquid water.

  7. Neutral Chemistry in Titan's Ionospheric Simulated Conditions

    NASA Astrophysics Data System (ADS)

    Dubois, David; Carrasco, Nathalie; Petrucciani, Marie; Tigrine, Sarah; Vettier, Ludovic

    2016-10-01

    Titan's atmospheric gas phase chemistry leading to the formation of organic aerosols can be simulated in laboratory experiments. Typically, plasma reactors can be used to achieve Titan-like conditions. Such a discharge induces dissociation and ionization processes to the N2-CH4 mixture by electron impact. This faithfully reproduces the electron energy range of magnetospheric electrons entering Titan's atmosphere and can also approximate the solar UV input at Titan's ionosphere. In this context, it is deemed necessary to apply and exploit such a technique in order to better understand the chemical reactivity occurring in Titan-like conditions.In the present work, we use the PAMPRE cold dusty plasma experiment with an N2-CH4 gaseous mixture under controlled pressure and gas influx, hence, emphasizing on the gas phase which we know is key to the formation of aerosols on Titan. Besides, an internal cryogenic trap has been developed to accumulate the gas products during their formation and facilitate their detection. These products are identified and quantified by in situ mass spectroscopy and Fourier-Transform Infrared Spectroscopy. We present here results from this experiment in two experimental conditions: 90-10% and 99-1% N2-CH4 mixing ratios respectively. We use a quantitative approach on nitriles and polycyclic aromatic hydrocarbons.Key organic compounds reacting with each other are thus detected and quantified in order to better follow the chemistry occuring in the gas phase of Titan-like conditions. Indeed, these species acting as precursors to the solid phase are assumed to be relevant in the formation of Titan's organic aerosols. These organic aerosols are what make up Titan's hazy atmosphere.

  8. Acceleration of electrons in Titan's ionosphere

    NASA Astrophysics Data System (ADS)

    Zaitsev, V. V.; Shaposhnikov, V. E.; Khodachenko, M. L.; Rucker, H. O.; Panchenko, M.

    2010-03-01

    A consideration of the acceleration mechanism which supplies the fast electrons to the source of Saturnian kilometric radiation (SKR) and an interpretation of the recently reported observational indications of the influence of Titan on the SKR are presented. The proposed mechanism operates by the effect of the different magnetization of the electrons and ions in Titan's ionosphere which in the course of Titan's motion through the Saturnian magnetic field causes the creation of a charge-separation electric field. This field has a component parallel to the magnetic field and accelerates part of the ionospheric electrons (called “runaway electrons”). The performed estimates show that the mechanism accelerates the runaway electrons up to an energy of ˜5 keV. The power of the acceleration mechanism is sufficient for SKR generation and also for the ultraviolet luminescence of Titan's atmosphere. The weakening of the SKR when Titan passes on the dayside of Saturn is due to a decrease of the magnetic field strength near the dayside magnetopause, when the Moon escapes the Saturnian magnetosphere, as well as due to the break in the magnetic connection between the electron acceleration region on Titan and the SKR sources. The latter prevents the penetration of the accelerated electrons into the radiation generation region. When Titan is on the nightside of Saturn, it enters into shell L˜14, which is stretched owing to the ring current. In this case, the electrons that accelerated in the ionosphere of Titan can reach the nightside SKR sources and activate them and therefore being the reason for the Titan influence on the SKR.

  9. Identification of Acetylene on Titan's Surface

    NASA Astrophysics Data System (ADS)

    Singh, S.; McCord, T. B.; Rodriguez, S.; Combe, J. P.; Cornet, T.; Le Mouelic, S.; Maltagliati, L.; Chevrier, V.; Clark, R. N.

    2015-12-01

    Titan's atmosphere is opaque in the near infrared due to gaseous absorptions, mainly by methane, and scattering by aerosols, except in a few "transparency windows" (e.g., Sotin et al., 2005). Thus, the composition of Titan surface remains difficult to access from space and is still poorly constrained, limited to ethane in the polar lakes (Brown et al., 2008) and a few possible organic molecules on the surface (Clark et al., 2010). Photochemical models suggest that most of the organic compounds formed in the atmosphere are heavy enough to condense and build up at the surface in liquid and solid states over geological timescale (Cordier et al., 2009, 2011). Acetylene (C2H2) is one of the most abundant organic molecules in the atmosphere and thus thought to present on the surface as well. Here we report direct evidence of solid C2H2 on Titan's surface using Cassini Visual and Infrared Mapping Spectrometer (VIMS) data. By comparing VIMS observations and laboratory measurements of solid and liquid C2H2, we identify a specific absorption at 1.55 µm that is widespread over Titan but is particularly strong in the brightest terrains. This surface variability suggests that C2H2 is mobilized by surface processes, such as surface weathering, topography, and dissolution/evaporation. The detection of C2H2 on the surface of Titan opens new paths to understand and constrain Titan's surface activity. Since C2H2 is highly soluble in Titan liquids (Singh et al. 2015), it can easily dissolve in methane/ethane and may play an important role in carving of fluvial channels and existence of karstic lakes at higher latitudes on Titan. These processes imply the existence of a dynamic surface with a continued history of erosion and deposition of C2H2 on Titan.

  10. Titan's organic chemistry: Results of simulation experiments

    NASA Technical Reports Server (NTRS)

    Sagan, Carl; Thompson, W. Reid; Khare, Bishun N.

    1992-01-01

    Recent low pressure continuous low plasma discharge simulations of the auroral electron driven organic chemistry in Titan's mesosphere are reviewed. These simulations yielded results in good accord with Voyager observations of gas phase organic species. Optical constants of the brownish solid tholins produced in similar experiments are in good accord with Voyager observations of the Titan haze. Titan tholins are rich in prebiotic organic constituents; the Huygens entry probe may shed light on some of the processes that led to the origin of life on Earth.

  11. The greenhouse and antigreenhouse effects on Titan

    NASA Technical Reports Server (NTRS)

    Mckay, Christopher P.; Pollack, James B.; Courtin, Regis

    1991-01-01

    The parallels between the atmospheric thermal structure of the Saturnian satellite Titan and the hypothesized terrestrial greenhouse effect can serve as bases for the evaluation of competing greenhouse theories. Attention is presently drawn to the similarity between the roles of H2 and CH4 on Titan and CO2 and H2O on earth. Titan also has an antigreenhouse effect due to a high-altitude haze layer which absorbs at solar wavelengths, while remaining transparent in the thermal IR; if this haze layer were removed, the antigreenhouse effect would be greatly reduced, exacerbating the greenhouse effect and raising surface temperature by over 20 K.

  12. Mapping products of Titan's surface: Chapter 19

    USGS Publications Warehouse

    Stephan, Katrin; Jaumann, Ralf; Karkoschka, Erich; Kirk, Randolph L.; Barnes, Jason W.; Tomasko, Martin G.; Turtle, Elizabeth P.; Le Corre, Lucille; Langhans, Mirjam; Le Mouélic, Stéphane; Lorenz, Ralph D.; Perry, Jason; Brown, Robert; Lebreton, Jean-Pierre; Waite, J. Hunter

    2010-01-01

    Remote sensing instruments aboard the Cassini spacecraft have been observed the surface of Titan globally in the infrared and radar wavelength ranges as well as locally by the Huygens instruments revealing a wealth of new morphological features indicating a geologically active surface. We present a summary of mapping products of Titan's surface derived from data of the remote sensing instruments onboard the Cassini spacecraft (ISS, VIMS, RADAR) as well as the Huygens probe (DISR) that were achieved during the nominal Cassini mission including an overview of Titan's recent nomenclature.

  13. Planetary science. The weather on Titan.

    PubMed

    Lorenz, R D

    2000-10-20

    When the Voyager 1 spacecraft returned images in 1980, the dense atmosphere of Saturn's moon Titan was assumed to be bland and featureless. As Lorenz discusses in his Perspective, recent ground-based spectroscopy, and images from the Hubble Space Telescope, are changing this perception. Observations such as the short-lived clouds in Titan's atmosphere reported by Griffith et al. suggest that although average precipitation is likely to be low, individual precipitation events may be heavy enough to cause deep valleys on Titan's surface.

  14. Detection of daily clouds on Titan.

    PubMed

    Griffith, C A; Hall, J L; Geballe, T R

    2000-10-20

    We have discovered frequent variations in the near-infrared spectrum of Titan, Saturn's largest moon, which are indicative of the daily presence of sparse clouds covering less than 1% of the area of the satellite. The thermodynamics of Titan's atmosphere and the clouds' altitudes suggest that convection governs their evolutions. Their short lives point to the presence of rain. We propose that Titan's atmosphere resembles Earth's, with clouds, rain, and an active weather cycle, driven by latent heat release from the primary condensible species.

  15. Planetary science. The weather on Titan.

    PubMed

    Lorenz, R D

    2000-10-20

    When the Voyager 1 spacecraft returned images in 1980, the dense atmosphere of Saturn's moon Titan was assumed to be bland and featureless. As Lorenz discusses in his Perspective, recent ground-based spectroscopy, and images from the Hubble Space Telescope, are changing this perception. Observations such as the short-lived clouds in Titan's atmosphere reported by Griffith et al. suggest that although average precipitation is likely to be low, individual precipitation events may be heavy enough to cause deep valleys on Titan's surface. PMID:11183770

  16. Ablation response testing of simulated radioisotope power supplies

    NASA Astrophysics Data System (ADS)

    Lutz, Steven A.; Chan, Chris C.

    1994-05-01

    Results of an experimental program to assess the aerothermal ablation response of simulated radioisotope power supplies are presented. Full-scale general purpose heat source, graphite impact shell, and lightweight radioisotope heater unit test articles are all tested without nuclear fuel in simulated reentry environments. Convective stagnation heating, stagnation pressure, stagnation surface temperature, surface recession profile, and weight loss measurements are obtained for diffusion-limited and sublimation ablation conditions. The recession profile and weight loss measurements show an effect of surface features on the stagnation face. The surface features alter the local heating which in turn affects the local ablation.

  17. Ablative Thermal Response Analysis Using the Finite Element Method

    NASA Technical Reports Server (NTRS)

    Dec John A.; Braun, Robert D.

    2009-01-01

    A review of the classic techniques used to solve ablative thermal response problems is presented. The advantages and disadvantages of both the finite element and finite difference methods are described. As a first step in developing a three dimensional finite element based ablative thermal response capability, a one dimensional computer tool has been developed. The finite element method is used to discretize the governing differential equations and Galerkin's method of weighted residuals is used to derive the element equations. A code to code comparison between the current 1-D tool and the 1-D Fully Implicit Ablation and Thermal Response Program (FIAT) has been performed.

  18. Integration of PanDA workload management system with Titan supercomputer at OLCF

    NASA Astrophysics Data System (ADS)

    De, K.; Klimentov, A.; Oleynik, D.; Panitkin, S.; Petrosyan, A.; Schovancova, J.; Vaniachine, A.; Wenaus, T.

    2015-12-01

    The PanDA (Production and Distributed Analysis) workload management system (WMS) was developed to meet the scale and complexity of LHC distributed computing for the ATLAS experiment. While PanDA currently distributes jobs to more than 100,000 cores at well over 100 Grid sites, the future LHC data taking runs will require more resources than Grid computing can possibly provide. To alleviate these challenges, ATLAS is engaged in an ambitious program to expand the current computing model to include additional resources such as the opportunistic use of supercomputers. We will describe a project aimed at integration of PanDA WMS with Titan supercomputer at Oak Ridge Leadership Computing Facility (OLCF). The current approach utilizes a modified PanDA pilot framework for job submission to Titan's batch queues and local data management, with light-weight MPI wrappers to run single threaded workloads in parallel on Titan's multicore worker nodes. It also gives PanDA new capability to collect, in real time, information about unused worker nodes on Titan, which allows precise definition of the size and duration of jobs submitted to Titan according to available free resources. This capability significantly reduces PanDA job wait time while improving Titan's utilization efficiency. This implementation was tested with a variety of Monte-Carlo workloads on Titan and is being tested on several other supercomputing platforms. Notice: This manuscript has been authored, by employees of Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The publisher by accepting the manuscript for publication acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes.

  19. Titan's Atmospheric Dynamics and Meteorology

    NASA Technical Reports Server (NTRS)

    Flasar, F. M.; Baines, K. H.; Bird, M. K.; Tokano, T.; West, R. A.

    2008-01-01

    Titan, after Venus, is the second example of an atmosphere with a global cyclostrophic circulation in the solar system, but a circulation that has a strong seasonal modulation in the middle atmosphere. Direct measurement of Titan's winds, particularly observations tracking the Huygens probe at 10degS, indicate that the zonal winds are generally in the sense of the satellites rotation. They become cyclostrophic approx. 35 km above the surface and generally increase with altitude, with the exception of a sharp minimum centered near 75 km, where the wind velocity decreases to nearly zero. Zonal winds derived from the temperature field retrieved from Cassini measurements, using the thermal wind equation, indicate a strong winter circumpolar vortex, with maximum winds at mid northern latitudes of 190 ms-' near 300 km. Above this level, the vortex decays. Curiously, the zonal winds and temperatures are symmetric about a pole that is offset from the surface pole by approx.4 degrees. The cause of this is not well understood, but it may reflect the response of a cyclostrophic circulation to the offset between the equator, where the distance to the rotation axis is greatest, and the solar equator. The mean meridional circulation can be inferred from the temperature field and the meridional distribution of organic molecules and condensates and hazes. Both the warm temperatures in the north polar region near 400 km and the enhanced concentration of several organic molecules suggests subsidence there during winter and early spring. Stratospheric condensates are localized at high northern latitudes, with a sharp cut-off near 50degN. Titan's winter polar vortex appears to share many of the same characteristics of winter vortices on Earth-the ozone holes. Global mapping of temperatures, winds, and composition in he troposphere, by contrast, is incomplete. The few suitable discrete clouds that have bee found for tracking indicate smaller velocities than aloft, consistent with the

  20. Micropillar fabrication on bovine cortical bone by direct-write femtosecond laser ablation

    NASA Astrophysics Data System (ADS)

    Lim, Yong C.; Altman, Katrina J.; Farson, Dave F.; Flores, Katharine M.

    2009-11-01

    We investigated fabrication of cylindrical micropillars on bovine cortical bone using direct-write femtosecond laser ablation. The ablation threshold of the material was measured by single-pulse ablation tests, and the incubation coefficient was measured from linear scanned ablation tests. A motion system was programmed to apply multiple layers of concentric rings of pulses to machine pillars of various diameters and heights. The diameter of the top surface of the pillar was found to steadily decrease due to incubation of damage from successive layers of pulses during the machining process. Pillar top diameter was predicted based on a paraxial beam fluence approximation and single-pulse ablation threshold and incubation coefficient measurements. Pillar diameters predicted as successive layers of pulses were applied were well-matched to experiments, confirming that femtosecond laser ablation of the cortical bone was well-modeled by single-pulse ablation threshold measurements and an incubation coefficient.

  1. Family System of Advanced Charring Ablators for Planetary Exploration Missions

    NASA Technical Reports Server (NTRS)

    Congdon, William M.; Curry, Donald M.

    2005-01-01

    Advanced Ablators Program Objectives: 1) Flight-ready(TRL-6) ablative heat shields for deep-space missions; 2) Diversity of selection from family-system approach; 3) Minimum weight systems with high reliability; 4) Optimized formulations and processing; 5) Fully characterized properties; and 6) Low-cost manufacturing. Definition and integration of candidate lightweight structures. Test and analysis database to support flight-vehicle engineering. Results from production scale-up studies and production-cost analyses.

  2. Ablation and radiation coupled viscous hypersonic shock layers, volume 1

    NASA Technical Reports Server (NTRS)

    Engel, C. D.

    1971-01-01

    The results for a stagnation-line analysis of the radiative heating of a phenolic-nylon ablator are presented. The analysis includes flow field coupling with the ablator surface, equilibrium chemistry, a step-function diffusion model and a coupled line and continuum radiation calculation. This report serves as the documentation, i e. users manual and operating instructions for the computer programs listed in the report.

  3. Titan's South Polar Vortex in Motion

    NASA Video Gallery

    This movie captured by NASA'S Cassini spacecraft shows a south polar vortex, or a swirling mass of gas around the pole in the atmosphere, at Saturn’s moon Titan. The swirling mass appears to exec...

  4. Taking on Titan: Meet Carrie Anderson

    NASA Video Gallery

    When she was a little girl, Carrie Anderson dreamed of becoming an astronomer. Now, as a space scientist at NASA Goddard Space Flight Center, Carrie studies the atmosphere on Titan: one of Saturn's...

  5. Cyanide Soap? Dissolved material in Titan's Seas

    NASA Astrophysics Data System (ADS)

    Lorenz, R. D.; Lunine, J. I.; Neish, C. D.

    2011-10-01

    Although it is evident that Titan's lakes and seas are dominated by ethane, methane, nitrogen, and (in some models) propane, there is divergence on the predicted relative abundance of minor constituents such as nitriles and C-4 alkanes. Nitriles such as hydrogen cyanide and acetonitrile, which have a significant dipole moment, may have a disproportionate influence on the dielectric properties of Titan seas and may act to solvate polar molecules such as water ice. The hypothesis is offered that such salvation may act to enhance the otherwise negligible solubility of water ice bedrock in liquid hydrocarbons. Such enhanced solubility may permit solution erosion as a formation mechanism for the widespread pits and apparently karstic lakes on Titan. Prospects for testing this hypothesis in the laboratory, and with measurements on Titan, will be discussed.

  6. Geomorphologic Map of Titan's Polar Terrains

    NASA Astrophysics Data System (ADS)

    Birch, S. P. D.; Hayes, A. G.; Malaska, M. J.; Lopes, R. M. C.; Schoenfeld, A.; Williams, D. A.

    2016-06-01

    Titan's lakes and seas contain vast amounts of information regarding the history and evolution of Saturn's largest moon. To understand this landscape, we created a geomorphologic map, and then used our map to develop an evolutionary model.

  7. The tide in the seas of Titan

    NASA Technical Reports Server (NTRS)

    Sagan, C.; Dermott, S. F.

    1982-01-01

    The parameters of the tides in the near-global ocean that may exist on Titan are assessed. A formula for the difference between the maximum heights of the oceanic and body tides is used to determine that the amplitude of the apparent, near-stationary, oceanic tide on Titan is greater than about 100 m. The effects of tidal dissipation are evaluated, showing that the amplitude of the tide will vary by nine percent over its 15.95-day period. The observed eccentricity of Titan's orbit is used to establish limits on the satellite's surface topography and oceanic depths. It is concluded that either Titan is covered by a near-global methane ocean over 400 m deep, or that there is no methane ocean at all. Reflectivity measurements can decide between these alternatives.

  8. Ion Neutral Mass Spectrometer Measurements from Titan

    NASA Astrophysics Data System (ADS)

    Waite, J. H., Jr.; Niemann, H.; Yelle, R. V.; Kasprzak, W.; Cravens, T.; Luhmann, J.; McNutt, R.; Ip, W.-H.; Gell, D.; Muller-Wordag, I. C. F.; Ledvina, S.; Magee, B.; Borggren, N.; Fletcher, G.; Walter, E.; Miller, R.; Xu, J.; Block, B.; Arnett, K.

    2005-03-01

    In its first flyby of Titan, Cassini/INMS has found that the upper atmospheric structure remains virtually unchanged since the Voyager flyby 20 years ago. The data also provides isotopic clues about the evolution of the atmosphere.

  9. Prebiotic-like chemistry on Titan.

    PubMed

    Raulin, François; Brassé, Coralie; Poch, Olivier; Coll, Patrice

    2012-08-21

    Titan, the largest satellite of Saturn, is the only one in the solar system with a dense atmosphere. Mainly composed of dinitrogen with several % of methane, this atmosphere experiences complex organic processes, both in the gas and aerosol phases, which are of prebiotic interest and within an environment of astrobiological interest. This tutorial review presents the different approaches which can be followed to study such an exotic place and its chemistry: observation, theoretical modeling and experimental simulation. It describes the Cassini-Huygens mission, as an example of observational tools, and gives the new astrobiologically oriented vision of Titan which is now available by coupling the three approaches. This includes the many analogies between Titan and the Earth, in spite of the much lower temperature in the Saturn system, the complex organic chemistry in the atmosphere, from the gas to the aerosol phases, but also the potential organic chemistry on Titan's surface, and in its possible internal water ocean.

  10. Prebiotic-like chemistry on Titan.

    PubMed

    Raulin, François; Brassé, Coralie; Poch, Olivier; Coll, Patrice

    2012-08-21

    Titan, the largest satellite of Saturn, is the only one in the solar system with a dense atmosphere. Mainly composed of dinitrogen with several % of methane, this atmosphere experiences complex organic processes, both in the gas and aerosol phases, which are of prebiotic interest and within an environment of astrobiological interest. This tutorial review presents the different approaches which can be followed to study such an exotic place and its chemistry: observation, theoretical modeling and experimental simulation. It describes the Cassini-Huygens mission, as an example of observational tools, and gives the new astrobiologically oriented vision of Titan which is now available by coupling the three approaches. This includes the many analogies between Titan and the Earth, in spite of the much lower temperature in the Saturn system, the complex organic chemistry in the atmosphere, from the gas to the aerosol phases, but also the potential organic chemistry on Titan's surface, and in its possible internal water ocean. PMID:22481630

  11. Future Exploration of Titan and Enceladus

    NASA Astrophysics Data System (ADS)

    Matson, D. L.; Coustenis, A.; Lunine, J.; Lebreton, J.; Reh, K.; Beauchamp, P.

    2009-05-01

    The future exploration of Titan and Enceladus has become very important for the planetary community. The study conducted last year of the Titan Saturn System Mission (TSSM) led to an announcement in which ESA and NASA prioritized future OPF missions, stating that TSSM is planned after EJSM (for details see http://www.lpi.usra.edu/opag/). TSSM consists of a TSSM Orbiter that would carry two in situ elements: the Titan Montgolfiere hot air balloon and the Titan Lake Lander. The mission could launch in the 2023-2025 timeframe on a trajectory to arrive ~9 years later for a 4-year mission in the Saturn system. Soon after arrival at Saturn, the montgolfiere would be delivered to Titan to begin its mission of airborne, scientific observations of Titan from an altitude of about 10 km. The montgolfiere would have a Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) power system and would be designed to last at least 6-12 months in Titan's atmosphere. With the predicted winds and weather, that would be sufficient to circumnavigate the globe! On a subsequent fly-by, the TSSM orbiter would release the Lake Lander on a trajectory toward Titan for a targeted entry. It would descend through the atmosphere making scientific measurements, much like Huygens did, and then land and float on one of Titan's seas. This would be its oceanographic phase, making a physical and chemical assessment of the sea. The Lake Lander would operate 8-10 hours until its batteries become depleted. Following the delivery of the in situ elements, the TSSM orbiter would explore the Saturn system via a 2-year tour that includes in situ sampling of Enceladus' plumes as well as Titan flybys. After the Saturn system tour, the TSSM orbiter would enter orbit around Titan for a global survey phase. Synergistic and coordinated observations would be carried out between the TSSM orbiter and the in situ elements. The scientific requirements were developed by the international TSSM Joint Science Definition

  12. Energy Deposition Processes in Titan's Upper Atmosphere

    NASA Technical Reports Server (NTRS)

    Sittler, Edward C., Jr.; Bertucci, Cesar; Coates, Andrew; Cravens, Tom; Dandouras, Iannis; Shemansky, Don

    2008-01-01

    Most of Titan's atmospheric organic and nitrogen chemistry, aerosol formation, and atmospheric loss are driven from external energy sources such as Solar UV, Saturn's magnetosphere, solar wind and galactic cosmic rays. The Solar UV tends to dominate the energy input at lower altitudes of approximately 1100 km but which can extend down to approximately 400 km, while the plasma interaction from Saturn's magnetosphere, Saturn's magnetosheath or solar wind are more important at higher altitudes of approximately 1400 km, but the heavy ion plasma [O(+)] of approximately 2 keV and energetic ions [H(+)] of approximately 30 keV or higher from Saturn's magnetosphere can penetrate below 950km. Cosmic rays with energies of greater than 1 GeV can penetrate much deeper into Titan's atmosphere with most of its energy deposited at approximately 100 km altitude. The haze layer tends to dominate between 100 km and 300 km. The induced magnetic field from Titan's interaction with the external plasma can be very complex and will tend to channel the flow of energy into Titan's upper atmosphere. Cassini observations combined with advanced hybrid simulations of the plasma interaction with Titan's upper atmosphere show significant changes in the character of the interaction with Saturn local time at Titan's orbit where the magnetosphere displays large and systematic changes with local time. The external solar wind can also drive sub-storms within the magnetosphere which can then modify the magnetospheric interaction with Titan. Another important parameter is solar zenith angle (SZA) with respect to the co-rotation direction of the magnetospheric flow. Titan's interaction can contribute to atmospheric loss via pickup ion loss, scavenging of Titan's ionospheric plasma, loss of ionospheric plasma down its induced magnetotail via an ionospheric wind, and non-thermal loss of the atmosphere via heating and sputtering induced by the bombardment of magnetospheric keV ions and electrons. This

  13. Huygens will soon set off for Titan

    NASA Astrophysics Data System (ADS)

    1997-09-01

    When it parachutes slowly down to the surface of Titan, in November 2004, Huygens will unmask the most enigmatic object in the Solar System. Baffled and tantalized, space scientists don't know how this moon of Saturn acquired a dense atmosphere, which is rich in nitrogen like the Earth's air but also possesses many carbon compounds. The scientists can't say whether the surface of Titan is solid or liquid, or a bit of each. But many are convinced that Titan offers them their best chance of discovering what the Earth and its chemistry were like, before life began. A heat shield will protect Huygens as it slams into Titan's atmosphere at 20,000 kilometres per second. A succession of parachutes will adjust Titan's speed of descent through the atmosphere. Radio signals from the probe will convey the results to the Cassini orbiter, for relaying tothe Earth, and will also reveal how Huygens and its parachute are blown about by the winds of Titan, during the descent. Huygens carries six sets of instruments devised by multinational teams of scientists in Europe and the USA. They will analyse the chemical composition of the haze that hides Titan's surface. They will gauge the weather of Titan during Huygens' descent, and image the clouds and the surface. A surface science package will report the true nature of Titan's surface. A televised launch Cassini-Huygens will be launched by a NASA Titan IVB rocket from the Cape Canaveral Air Station in Florida. The earliest launch date is 6 October, but this is now likely to slip, to allow for the repair of minor damage to insulation within the Huygens probe (see ESA Press Release Nr 27-97). Provided the launch occurs before 4 November, there will be no delay in the arrival at Saturn and Titan. ESA will provide a live TV transmission, free of charge, for European news organizations and other organizations wishing to receive it. Live pictures of the launch will be accompanied by interviews with scientists and engineers of ESA's Huygens

  14. Adsorption of Acetylene and Formation of Benzene on Cosmic Dust in Titan's Atmosphere

    NASA Astrophysics Data System (ADS)

    Frankland, Victoria; James, Alexander; Carrillo Sanchez, Juan; Mangan, Thomas; Willacy, Karen; Plane, John

    2016-04-01

    The formation of the haze layers and tholins in Titan's atmosphere is unclear. One potential mechanism is that small precursors, such as acetylene (C2H2), adsorb onto un-ablated cosmic dust particles as they sediment through Titan's atmosphere. The uptake coefficient of C2H2 onto cosmic dust analogues was measured using low temperature dual flow tube apparatus. Synthesized olivines analogues (Mg2-2nFe2nSiO4 where 1 ≥ n ≥ 0) were used to represent the cosmic dust particles based on investigations of cometary dust. The results indicated that the adsorption of C2H2 was independent of the Mg:Fe ratio in the dust analogue with the mean uptake coefficient (at 181 K) as 1.7 × 10-4. In some cases, the uptake experiments were left until the surface had become saturated with C2H2. Here, a small benzene (C6H6) mass trace was detected indicating that cyclotrimerzation of C2H2 into C6H6 was occurring on the surface. Further experiments using ultrahigh vacuum apparatus were used to confirm this observation. The rate of C6H6 (formed through C2H2 cyclotrimerization) desorbing from un-ablated cosmic dust particles sedimenting through Titan's atmosphere was explored using a 1D model. The results revealed that this heterogeneous formation and desorption route was competitive with gaseous C6H6 formation rates suggesting that the dust could be acting as a seed for the formation of complex organic molecules (such as PAHs) and tholins and, through this, the formation of the haze layers.

  15. Uptake of acetylene on cosmic dust and production of benzene in Titan's atmosphere

    NASA Astrophysics Data System (ADS)

    Frankland, Victoria L.; James, Alexander D.; Sánchez, Juan Diego Carrillo; Mangan, Thomas P.; Willacy, Karen; Poppe, Andrew R.; Plane, John M. C.

    2016-11-01

    A low-temperature flow tube and ultra-high vacuum apparatus were used to explore the uptake and heterogeneous chemistry of acetylene (C2H2) on cosmic dust analogues over the temperature range encountered in Titan's atmosphere below 600 km. The uptake coefficient, γ, was measured at 181 K to be (1.6 ± 0.4) × 10-4, (1.9 ± 0.4) × 10-4 and (1.5 ± 0.4) × 10-4 for the uptake of C2H2 on Mg2SiO4, MgFeSiO4 and Fe2SiO4, respectively, indicating that γ is independent of Mg or Fe active sites. The uptake of C2H2 was also measured on SiO2 and SiC as analogues for meteoric smoke particles in Titan's atmosphere, but was found to be below the detection limit (γ < 6 × 10-8 and < 4 × 10-7, respectively). The rate of cyclo-trimerization of C2H2 to C6H6 was found to be 2.6 × 10-5 exp(-741/T) s-1, with an uncertainty ranging from ± 27 % at 115 K to ± 49 % at 181 K. A chemical ablation model was used to show that the bulk of cosmic dust particles (radius 0.02-10 μm) entering Titan's atmosphere do not ablate (< 1% mass loss through sputtering), thereby providing a significant surface for heterogeneous chemistry. A 1D model of dust sedimentation shows that the production of C6H6via uptake of C2H2 on cosmic dust, followed by cyclo-trimerization and desorption, is probably competitive with gas-phase production of C6H6 between 80 and 120 km.

  16. Nozzle designs with pitch precursor ablatives

    NASA Technical Reports Server (NTRS)

    Blevins, H. R.; Bedard, R. J.

    1976-01-01

    Recent developments in carbon phenolic ablatives for solid rocket motor nozzles have yielded a pitch precursor carbon fiber offering significant raw material availability and cost saving advantages as compared to conventional rayon precursor material. This paper discusses the results of an experimental program conducted to assess the thermal performance and characterize the thermal properties of pitch precursor carbon phenolic ablatives. The end result of this program is the complete thermal characterization of pitch fabric, pitch mat, hybrid pitch/rayon fabric and pitch mat molding compound. With these properties determined an analytic capability now exists for predicting the thermal performance of these materials in rocket nozzle liner applications. Further planned efforts to verify material performance and analytical prediction procedures through actual rocket motor firings are also discussed.

  17. Librations of Enceladus and Titan

    NASA Astrophysics Data System (ADS)

    Yseboodt, M.; Van Hoolst, T.; Baland, R. M.

    2015-12-01

    A moon in synchronous rotation has longitudinal librations (small deviations from the average rotation) because of its nonspherical mass distribution and its elliptical orbit around the planet. We study the long-period librations of Enceladus and Titan and include deformation effects and the existence of a subsurface ocean. We take into account the fact that the orbit is not Keplerian and has other periodicities than the main period of orbital motion around Saturn due to perturbations by the Sun, other planets and moons. An orbital theory is used to compute the orbital perturbations due to these other bodies.We numerically evaluate the amplitude of the long-period librations for many interior structure models of the moon constrained by the mass, radius and gravity field. Measurements of the librations may give constraints on the interior structure of the icy satellites.

  18. Parallel contingency statistics with Titan.

    SciTech Connect

    Thompson, David C.; Pebay, Philippe Pierre

    2009-09-01

    This report summarizes existing statistical engines in VTK/Titan and presents the recently parallelized contingency statistics engine. It is a sequel to [PT08] and [BPRT09] which studied the parallel descriptive, correlative, multi-correlative, and principal component analysis engines. The ease of use of this new parallel engines is illustrated by the means of C++ code snippets. Furthermore, this report justifies the design of these engines with parallel scalability in mind; however, the very nature of contingency tables prevent this new engine from exhibiting optimal parallel speed-up as the aforementioned engines do. This report therefore discusses the design trade-offs we made and study performance with up to 200 processors.

  19. Evidence for surface heterogeneity on Titan

    NASA Astrophysics Data System (ADS)

    Griffith, C. A.

    1993-08-01

    Observational results are presented for two rotational periods of Titan which exhibit the albedo difference noted by Lemmon et al. (1993) between this moon's positions at eastern and western elongation relative to Saturn. The persistence of this difference indicates that this heterogeneity is unlikely to be associated with transient features, and must be intrinsic to the surface. The results presented also indicate that Titan is locked in a synchronous orbit around Saturn.

  20. Saturn's Titan: Evidence for Current Cryovolcanic Activity

    NASA Astrophysics Data System (ADS)

    Nelson, Robert M.; Cassini VIMS Titan Surface Variability Group

    2009-09-01

    We report evidence suggesting current cryovolcanic activity on Titan. This is based on surface changes seen at selected locations by the Cassini Visual and Infrared Mapping Spectrometer (VIMS). Titan's surface is hard to observe because Titan's atmosphere is opaque at visual wavelengths due to methane absorption. However, VIMS is able to image the surface at selected infrared wavelengths where the methane is relatively transparent[1,2]. VIMS reported surface reflectance variability at Hotei Arcus (26S,78W) and that the variability might be due to deposition followed by coverage or dissipation of ammonia frost. Subsequently, Cassini RADAR images found that Hotei Arcus has lobate "flow” forms, consistent with the morphology of volcanic terrain [3]. Here we report the discovery of lobate "flow” patterns at Hotei Arcus in VIMS infrared images taken during Cassini close flybys during 2008-2009. These data further suggest that the brightness variability at Hotei Arcus is associated with ammonia, a compound expected in Titan's interior. This, combined with the previous evidence from VIMS and RADAR images, creates a strong case for Titan having a presently active surface, possibly due to cryovolcanism. It has not escaped our attention that gaseous ammonia, in association with methane and nitrogen in Titan's atmosphere, is similar to the terrestrial environment at the time that life first emerged. If Titan is currently active, then these results raise the following questions: What is the full extent of current geologic activity? What are the ongoing processes? Are Titan's chemical processes today supporting a prebiotic chemistry similar to that under which life evolved on Earth? This work done at JPL under contract with NASA. References: [1]R. M. Nelson et al., Icarus 199 (2009) 429-441. [2]R. M. Nelson et al., GEOPHYSICAL RESEARCH LETTERS, VOL. 36, L04202, doi:10.1029/2008GL036206, 2009. [3]S. D. Wall GEOPHYSICAL RESEARCH LETTERS, VOL. 36, L04203, doi:10.1029/2008GL

  1. Titan Orbiter with Aerorover Mission (TOAM)

    NASA Astrophysics Data System (ADS)

    Sittler, Edward C.; Cooper, J. F.; Mahaffey, P.; Esper, J.; Fairbrother, D.; Farley, R.; Pitman, J.; Kojiro, D. R.; TOAM Team

    2006-12-01

    We propose to develop a new mission to Titan called Titan Orbiter with Aerorover Mission (TOAM). This mission is motivated by the recent discoveries of Titan, its atmosphere and its surface by the Huygens Probe, and a combination of in situ, remote sensing and radar mapping measurements of Titan by the Cassini orbiter. Titan is a body for which Astrobiology (i.e., prebiotic chemistry) will be the primary science goal of any future missions to it. TOAM is planned to use an orbiter and balloon technology (i.e., aerorover). Aerobraking will be used to put payload into orbit around Titan. The Aerorover will probably use a hot air balloon concept using the waste heat from the MMRTG 500 watts. Orbiter support for the Aerorover is unique to our approach for Titan. Our strategy to use an orbiter is contrary to some studies using just a single probe with balloon. Autonomous operation and navigation of the Aerorover around Titan will be required, which will include descent near to the surface to collect surface samples for analysis (i.e., touch and go technique). The orbiter can provide both relay station and GPS roles for the Aerorover. The Aerorover will have all the instruments needed to sample Titan’s atmosphere, surface, possible methane lakes-rivers, use multi-spectral imagers for surface reconnaissance; to take close up surface images; take core samples and deploy seismometers during landing phase. Both active and passive broadband remote sensing techniques will be used for surface topography, winds and composition measurements.

  2. The rotation of Titan and Ganymede

    NASA Astrophysics Data System (ADS)

    Van Hoolst, Tim; Coyette, Alexis; Baland, Rose-Marie; Trinh, Antony

    2016-10-01

    The rotation rates of Titan and Ganymede, the largest satellites of Saturn and Jupiter, are on average equal to their orbital mean motion. Here we discuss small deviations from the average rotation for both satellites and evaluate the polar motion of Titan induced by its surface fluid layers. We examine different causes at various time scales and assess possible consequences and the potential of using librations and polar motion as probes of the interior structure of the satellites.The rotation rate of Titan and Ganymede cannot be constant on the orbital time scale as a result of the gravitational torque of the central planet acting on the satellites. Titan is moreover expected to show significant polar motion and additional variations in the rotation rate due to angular momentum exchange with the atmosphere, mainly at seasonal periods. Observational evidence for deviations from the synchronous state has been reported several times for Titan but is unfortunately inconclusive. The measurements of the rotation variations are based on determinations of the shift in position of Cassini radar images taken during different flybys. The ESA JUICE (JUpiter ICy moons Explorer) mission will measure the rotation variations of Ganymede during its orbital phase around the satellite starting in 2032.We report on different theoretical aspects of the librations and polar motion. We consider the influence of the rheology of the ice shell and take into account Cassini measurements of the external gravitational field and of the topography of Titan and similar Galileo data about Ganymede. We also evaluate the librations and polar motion induced by Titan's hydrocarbon seas and use the most recent results of Titan's atmosphere dynamics. We finally evaluate the potential of rotation variations to constrain the satellite's interior structure, in particular its ice shell and ocean.

  3. Spectral Trends of Titan's Tropical Surface

    NASA Astrophysics Data System (ADS)

    Griffith, Caitlin Ann; Penteado, Paulo F.; Turner, Jake; Montiel, Nicholas; Schoenfeld, Ashley; Lopes, Rosaly M. C.; Soderblom, Laurence A.; Neish, Catherine; Radebaugh, Jani

    2016-10-01

    Titan's surface can be observed most clearly at 8 spectral regions that lie in between the strong methane bands in Titan's spectrum. Within these "windows", between 0.9 to 5 microns, the surface is nonetheless obscured by methane and haze, the latter of which is optically thick at lower wavelengths. Thus studies of Titan's surface must eliminate the effects of atmospheric extinction and extract the subtle spectral features that underlie the dominant spectral trends.To determine the subtle spectral features of Titan's tropical surface (30S--30N) we conducted a Principal Components Analysis (PCA) of the I/F at the 1.1, 1.3, 1.6 and 2.0 um wavelength windows, recorded by Cassini/VIMS. The PCA analysis identifies the spectral trend that defines the highest variance in the data (the principal component), as well as successively weaker orthogonal trends, without a priori assumptions about the surface composition, e.g. as needed in radiative transfer analyses.Our analysis derives the spectral features at the four wavelengths that describe Titan's tropical surface. We detect a large almost contiguous region that extends roughly 160 degrees in longitude and which exhibits absorption features at 1.6 and 2.0, as well as 2.8 um (characteristic of water ice). This vast and perhaps tectonic feature is, in part, associated with terrain that is hypothesized to be some of the oldest surfaces on Titan. In addition, the PCA analysis indicates at least 2 separate organic spectra signatures, potentially due to the separation of liquid and refractory sediments or to their chemically alteration over time. Here we discuss the PCA analysis and compare our derived compositional maps of Titan's surface with Radar maps of the topography and morphology, to entertain questions regarding the geology of Titan's surface the age of its atmosphere.

  4. Atomic hydrogen distribution. [in Titan atmospheric model

    NASA Technical Reports Server (NTRS)

    Tabarie, N.

    1974-01-01

    Several possible H2 vertical distributions in Titan's atmosphere are considered with the constraint of 5 km-A a total quantity. Approximative calculations show that hydrogen distribution is quite sensitive to two other parameters of Titan's atmosphere: the temperature and the presence of other constituents. The escape fluxes of H and H2 are also estimated as well as the consequent distributions trapped in the Saturnian system.

  5. Titan's atmospheric engine: an overview

    NASA Astrophysics Data System (ADS)

    Samuelson, Robert E.

    2003-02-01

    Heating occurs in Titan's stratosphere from the absorption of incident solar radiation by methane and aerosols. About 10% of the incident sunlight reaches Titan's surface and causes heating there. Thermal radiation redistributes heat within the atmosphere and cools to space. The resulting vertical temperature profile is stable against convection and a state of radiative equilibrium is established. Equating theoretical and observed temperature profiles enables an empirical determination of the vertical distribution of thermal opacity. A uniformly mixed aerosol is responsible for most of the opacity in the stratosphere, whereas collision-induced absorption of gases is the main contributor in the troposphere. Occasional clouds are observed in the troposphere in spite of the large degrees of methane supersaturation found there. Photochemistry converts CH 4 and N 2 into more complex hydrocarbons and nitriles in the stratosphere and above. Thin ice clouds of trace organics are formed in the winter and early spring polar regions of the lower stratosphere. Precipitating ice particles serve as condensation sites for supersaturated methane vapor in the troposphere below, resulting in lowered methane degrees of supersaturation in the polar regions. Latitudinal variations of stratospheric temperature are seasonal, and lag instantaneous response to solar irradiation by about one season for two reasons: (1) an actual instantaneous thermal response to a latitudinal distribution of absorbing gases, themselves out of phase with the sun by about one season, and (2) a sluggish dynamical response of the stratosphere to the latitudinal transport of angular momentum, induced by radiative heating and cooling. Mean vertical abundances of stratospheric organics and aerosols are determined primarily by atmospheric chemistry and condensation, whereas latitudinal distributions are more influenced by meridional circulations. In addition to preferential scavenging by precipitating ice particles

  6. Condensation during Titan's Polar Winter

    NASA Astrophysics Data System (ADS)

    de Kok, Remco; Irwin, P. G.; Teanby, N. A.; Fletcher, L. N.; Howett, C. J.; Calcutt, S. B.; Bowles, N. E.; Taylor, F. W.

    2007-10-01

    Titan is currently experiencing winter in its northern hemisphere and the lower atmosphere of its north polar region has been in prolonged darkness since the solstice in October 2002. As a result, the north polar region is currently characterised by cold stratospheric temperatures and there is enrichment of trace gases due to downward atmospheric motion (e.g. Teanby et al., Icarus 181 pp. 243-255, 2006). These conditions make the polar winter very suitable for cloud formation in the stratosphere. A simple transport and condensation model has been made to explore condensation processes in Titan's northern stratosphere. In the model, the atmosphere is advected downwards and clouds are formed as the saturation pressure of various gases is reached. Upper limits of the gases C4N2 and propionitrile (C2H5CN) were determined from Cassini Composite Infrared Spectrometer data to assess scenarios of chemical disequilibrium where the gas phase is far less abundant than the solid phase. The upper limit for C4N2 is 9e-9, which discounts the massive C4N2 build-up in the polar winter proposed by Samuelson et al. (PSS 45, pp. 941-948, 1997) to explain the observed C4N2 cloud at the Voyager epoch. The propionitrile upper limit is 8e-9, which is several orders of magnitude less than needed to create the condensate feature at 220 cm-1 of Khanna (Icarus 177, pp. 116-121) and de Kok et al. (Icarus, in press), assuming it is propionitrile ice, under the steady-state conditions explored by the aformentioned model. HCN ice seems to play an important role in the formation of a massive polar cloud (Haze B in de Kok et al., Icarus, in press), because of the unavailability of sufficient condensable gas other than HCN (and possibly HC3N) to produce the condensate features seen in far-infrared spectra at 220 cm-1.

  7. Safe prescribing: a titanic challenge

    PubMed Central

    Routledge, Philip A

    2012-01-01

    The challenge to achieve safe prescribing merits the adjective ‘titanic’. The organisational and human errors leading to poor prescribing (e.g. underprescribing, overprescribing, misprescribing or medication errors) have parallels in the organisational and human errors that led to the loss of the Titanic 100 years ago this year. Prescribing can be adversely affected by communication failures, critical conditions, complacency, corner cutting, callowness and a lack of courage of conviction, all of which were also factors leading to the Titanic tragedy. These issues need to be addressed by a commitment to excellence, the final component of the ‘Seven C's’. Optimal prescribing is dependent upon close communication and collaborative working between highly trained health professionals, whose role is to ensure maximum clinical effectiveness, whilst also protecting their patients from avoidable harm. Since humans are prone to error, and the environments in which they work are imperfect, it is not surprising that medication errors are common, occurring more often during the prescribing stage than during dispensing or administration. A commitment to excellence in prescribing includes a continued focus on lifelong learning (including interprofessional learning) in pharmacology and therapeutics. This should be accompanied by improvements in the clinical working environment of prescribers, and the encouragement of a strong safety culture (including reporting of adverse incidents as well as suspected adverse drug reactions whenever appropriate). Finally, members of the clinical team must be prepared to challenge each other, when necessary, to ensure that prescribing combines the highest likelihood of benefit with the lowest potential for harm. PMID:22738396

  8. Airglow on Titan During Eclipse

    NASA Astrophysics Data System (ADS)

    West, R. A.; Ajello, J. M.; Stevens, M. H.; Strobel, D. F.; Gladstone, R.; Evans, J. S.; Bradley, E. T.

    2012-12-01

    Magnetospheric or cosmic ray charged particle precipitation into Titan's atmosphere is a potential energy source for driving chemistry and may contribute to airglow and energy balance. Estimates of the significance of these processes vary widely and thus far have been only poorly constrained because of the dominance of XUV radiation in stimulating UV airglow. To address these issues we observed Titan when it was deeply embedded in Saturn's shadow in 2009. We obtained EUV and FUV spectra with the Cassini Ultraviolet Imaging Spectrograph (UVIS) and images with the Cassini Imaging Science Subsystem (ISS) at visible wavelengths. For the first time, nitrogen emissions were seen in the spectra in the absence of XUV stimulation, although with insufficient spatial resolution to do limb profiling. The emissions are about a factor of ten smaller than peak dayside emissions observed with UVIS at closer range (from Stevens et al., , J. Geophys. Res., 116, A05304, doi10.1029/2010ja016284). Hydrogen emissions are also observed, consistent with the idea that precipitating protons and oxygen ions are responsible for part of the emission. The visible images from ISS contribute because they resolve the disk well. No auroral structures are seen. Rather, there is a very faint airglow seen on the limb between about 300 and 1000 km and a stronger intensity coming from the region of the haze at 300 km altitude. Although the limb glow is near the noise limit, the radial profile appears to be inconsistent with ionization profiles expected for precipitating electrons, protons, or oxygen ions which are expected to produce strong limb brightening. The stronger glow from the haze region was unexpected. Its origin is not understood but deeply-penetrating cosmic ray ionization and chemiluminescence are candidates that deserve additional scrutiny. . Part of this work was performed by the Jet Propulsion Lab, Cal. Inst. of Tech. under contract with the National Aeronautics and Space Administration.

  9. Titan 3E/Centaur D-1T Systems Summary

    NASA Technical Reports Server (NTRS)

    1973-01-01

    A systems and operational summary of the Titan 3E/Centaur D-1T program is presented which describes vehicle assembly facilities, launch facilities, and management responsibilities, and also provides detailed information on the following separate systems: (1) mechanical systems, including structural components, insulation, propulsion units, reaction control, thrust vector control, hydraulic systems, and pneumatic equipment; (2) astrionics systems, such as instrumentation and telemetry, navigation and guidance, C-Band tracking system, and range safety command system; (3) digital computer unit software; (4) flight control systems; (5) electrical/electronic systems; and (6) ground support equipment, including checkout equipment.

  10. Rubidium Ultra-Stable Oscillators at Titan: The Huygens Doppler Wind Experiment

    NASA Technical Reports Server (NTRS)

    Bird, M. K.; Allison, M.; Asmar, S. W.; Atkinson, D. H.; Dutta-Roy, R.; Edenhofer, P.; Folkner, W. M.; Heyl, M.; Iess, L.; Plettemeier, D.; Preston, R. A.; Tyler, G. L.; Wohlmuth, R.

    1997-01-01

    The Doppler Wind Experiment (DWE) is one of six investigations to be performed during the Titan atmospheric descent of the ESA Huygens Probe. The primary scientific objective is to measure the direction and strength of Titan's zonal winds with an accuracy better than 1 m/s. The Probe's wind-induced horizontal motion will be derived from the residual Doppler shift of its S-band radio link to the Cassini Orbiter, corrected for all known orbit and propagation effects, from the beginning of the mission (altitude: approx. 160 km) down to impact on the surface. The DWE Instrumentation consists of Rb-based Ultra-Stable Oscillators used to: (1) generate the transmitted signal from the Probe and (2) extract the frequency of the received signal on the Orbiter. The capabilities of these USOs under the rugged experimental conditions on Titan and some results from the DWE pre-launch test program are described.

  11. Nonthermal atmospheric escape from Mars and Titan

    NASA Astrophysics Data System (ADS)

    Lammer, H.; Bauer, S. J.

    1991-02-01

    Energy flux spectra and particle concentrations of the hot O and N coronae from Mars and Titan, respectively, resulting primarily from dissociative recombination of molecular ions, have been calculated by means of a Monte Carlo method. The calculated energy flux spectra lead to an escape flux phi(esc) about 6 x 10 to the 6th/sq cm per sec for Mars and phi(esc) about 2 x 10 to 6th/sq cm per sec for Titan, corresponding to a mass loss of about 0.14 kg/s for Mars and about 0.3 kg/s for Titan. (The contribution of electron impact ionization on N2 amounts to only about 25 percent of Titan's mass loss). Mass loss via solar and magnetospheric wind is also estimated using newly calculated mass loading limits. The mass loss via ion pickup from the extended hot atom corona for Mars amounts to about 0.25 kg/s (O/+/) and for Titan to about 50 g/s (N2/+/or H2CN/+/). Thus, the total mass loss rate from Mars and Titan is about the same (i.e., 0.4 kg/s).

  12. A facility for simulating Titan's environment

    NASA Astrophysics Data System (ADS)

    Wasiak, F. C.; Luspay-Kuti, A.; Welivitiya, W. D. D. P.; Roe, L. A.; Chevrier, V. F.; Blackburn, D. G.; Cornet, T.

    2013-04-01

    As a result of measurements acquired by the Cassini-Huygens mission of Titan's near surface atmospheric composition and temperature, Titan conditions can now be simulated in the laboratory and samples can subsequently be subjected to those conditions. Titan demonstrates an active hydrological-like cycle with its thick atmosphere, dynamic clouds, polar lakes of methane and ethane, moist regolith, and extensive fluvial erosive features. Unlike Earth, Titan's hydrological-like cycle likely involves several constituents, primarily methane and ethane. Here the properties of a new Titan simulation facility are presented, including conceptual methodology, design, implementation, and performance results. The chamber maintains Titan's surface temperature and pressure, and the sample cryogenic liquids undergoing experimentation are condensed within the chamber itself. During the experiments, the evaporation rates of the sample liquids are directly determined by continually measuring mass. Constituents are analyzed utilizing a Fourier Transform Infrared Spectroscopy (FTIR), and vapor concentrations are determined using a gas chromatograph fitted with a Flame Ionization Detector (FID). All pertinent data is logged via computer. Under laboratory conditions, the direct measurements of the evaporation rates of methane, ethane, and mixtures thereof can be achieved. Among the processes to be studied are the effects of regolith on transport from the subsurface to the atmosphere, the freezing point depression effects of dissolved nitrogen, and the solubility of various relevant organic compounds.

  13. Ammonia and the Interior of Titan

    NASA Astrophysics Data System (ADS)

    Lorenz, R. D.

    2002-12-01

    Titan's surface will be very different from those of the Galileans, not just because of interactions with the atmosphere, but because the internal evolution will have been unique. The incorporation of ammonia in the ices making up Titan will make the evolution of Titan's interior structure very different. The presence of ammonia was previously only hinted at by formation models and the remarkably thick nitrogen atmosphere. However, recent radar observations showing Iapetus' bright face to be surprisingly radar-dark also point to incorporation of ammonia in the ices of the Saturnian satellites, explaining Titan's radar-darkness too. Ammonia will have several effects. As is well-known, its freezing-point depression to 176K makes a liquid layer ('internal ocean') more likely. A significant difference compared with the Galileans is that the greater expansivity of ammonia solutions compared with pure water causes the adiabat to be steeper, and thus a greater temperature difference prevails across the liquid layer. This in turn leads to a higher Carnot efficiency for the mantle heat engine - by an order of magnitude compared with Callisto - suggesting endogenic activity may be more manifest on Titan than on its Galilean cousins. The replenishment of methane in Titan's atmosphere against photolysis requires either surface lakes, or volcanic replenishment. If plausible methane contents of water-ammonia cryolavas are assumed, the heat flux associated with volcanism can be easily accommodated by the expected radiogenic heat production in the rocky core.

  14. Handling Late Changes to Titan Science

    NASA Technical Reports Server (NTRS)

    Pitesky, Jo Eliza; Steadman, Kim; Ray, Trina; Burton, Marcia

    2014-01-01

    The Cassini mission has been in orbit for eight years, returning a wealth of scientific data from Titan and the Saturnian system. The mission, a cooperative undertaking between NASA, ESA and ASI, is currently in its second extension of the prime mission. The Cassini Solstice Mission (CSM) extends the mission's lifetime until Saturn's northern summer solstice in 2017. The Titan Orbital Science Team (TOST) has the task of integrating the science observations for all 56 targeted Titan flybys in the CSM. In order to balance Titan science across the entire set of flybys during the CSM, to optimize and influence the Titan flyby altitudes, and to decrease the future workload, TOST went through a "jumpstart" process before the start of the CSM. The "jumpstart" produced Master Timelines for each flyby, identifying prime science observations and allocating control of the spacecraft attitude to specific instrument teams. Three years after completing this long-range plan, TOST now faces a new challenge: incorporating changes into the Titan Science Plan without undoing the balance achieved during the jumpstart.

  15. The Chemical Evolution of Titan's Atmosphere

    NASA Astrophysics Data System (ADS)

    Kaiser, Ralf I.

    2010-11-01

    Astrochemistry or Astrochemical Dynamics presents a newly emerging, interdisciplinary and innovative field comprising scientists in chemistry, physics, biology, astronomy, and planetary chemistry. The prime directive of Astrochemical Dynamics is to understand the origin and chemical evolution of the interstellar medium and of our Solar System. Here, the arrival of the Cassini-Huygens probe at Saturn's moon Titan - the only Solar System body besides Earth and Venus with a solid surface and thick atmosphere - in 2004 opened up a new chapter in the history of Solar System exploration. Titan's most prominent optically visible features are the aerosol-based haze layers, which give Titan its orange-brownish color. However, the underlying chemical processes, which initiate the haze formation, have been the least understood to date. This talk reviews recent laboratory studies on the role of polyacetylenes (polyynes) and (hetero)aromatic molecules like the phenyl radical, benzene, and pyridine in the formation of Titan's organic haze layers utilizing crossed molecular beam experiments. Those investigations provide key concepts on the formation mechanisms of unsaturated hydrocarbon molecules - in particular polyynes and aromatic compounds - together with their hydrogen deficient precursors from the "bottom up" in the atmosphere of Saturn's moon Titan. A brief outline to future research directions tackling also the heterogeneous chemistry on Titan and in hydrocarbon-rich atmospheres in the outer Solar System in general will also be presented.

  16. Luminescence studies of perovskite structured titanates: A review

    NASA Astrophysics Data System (ADS)

    Nag Bhargavi, G.; Khare, Ayush

    2015-06-01

    Apart from widely known dielectric and ferroelectric properties, the perovskite type materials also constitute a class of materials, which are recently investigated for their optical properties. These materials are being used for fabrication of various microelectronics and optoelectronic devices. Photoluminescence (PL), mechanoluminescence (ML) and thermoluminescence (TL) are such phenomena offering numerous applications in different fields like electro-optics, flat panel displays, LED technology, sensors, dynamic visualization etc. This paper briefly reviews the status and new progress in luminescence studies of ferroelectric materials like barium titanate (BT), barium zirconate titanate (BZT), calcium titanate (CT), calcium zirconate titanate (CZT), lead titanate (PT), lead zirconate titanate (PZT), etc., prepared through various methods.

  17. Ablation of Martian glaciers

    NASA Technical Reports Server (NTRS)

    Moore, Henry J.; Davis, Philip A.

    1987-01-01

    Glacier like landforms are observed in the fretted terrain of Mars in the latitude belts near + or - 42 deg. It was suggested that sublimation or accumulation-ablation rates could be estimated for these glaciers if their shapes were known. To this end, photoclinometric profiles were obtained of a number of these landforms. On the basis of analyses of these profiles, it was concluded that ice is chiefly ablating from these landforms that either are inactive rock-glaciers or have materials within them that are moving exceedingly slowly at this time. These conclusions are consistent with other geologic information. The analyses were performed using a two-dimensional model of an isothermal glacier.

  18. Dissolution on Titan and on Earth: Toward the age of Titan's karstic landscapes

    NASA Astrophysics Data System (ADS)

    Cornet, Thomas; Cordier, Daniel; Bahers, Tangui Le; Bourgeois, Olivier; Fleurant, Cyril; Mouélic, Stéphane Le; Altobelli, Nicolas

    2015-06-01

    Titan's polar surface is dotted with hundreds of lacustrine depressions. Based on the hypothesis that they are karstic in origin, we aim at determining the efficiency of surface dissolution as a landshaping process on Titan, in a comparative planetology perspective with the Earth as reference. Our approach is based on the calculation of solutional denudation rates and allow inference of formation timescales for topographic depressions developed by chemical erosion on both planetary bodies. The model depends on the solubility of solids in liquids, the density of solids and liquids, and the average annual net rainfall rates. We compute and compare the denudation rates of pure solid organics in liquid hydrocarbons and of minerals in liquid water over Titan and Earth timescales. We then investigate the denudation rates of a superficial organic layer in liquid methane over one Titan year. At this timescale, such a layer on Titan would behave like salts or carbonates on Earth depending on its composition, which means that dissolution processes would likely occur but would be 30 times slower on Titan compared to the Earth due to the seasonality of precipitation. Assuming an average depth of 100 m for Titan's lacustrine depressions, these could have developed in a few tens of millions of years at polar latitudes higher than 70°N and S, and a few hundreds of million years at lower polar latitudes. The ages determined are consistent with the youth of the surface (<1 Gyr) and the repartition of dissolution-related landforms on Titan.

  19. [Ablative and fractional lasers].

    PubMed

    Beylot, C; Grognard, C; Michaud, T

    2009-10-01

    The use of pulsed or scanning Carbon Dioxide, and pulsed Erbium-YAG lasers allows the programmable and reproducible photocoagulation of thin layers of the epidermis and superficial dermis. Thermal damage depends on the type of laser and is greater with CO(2) lasers. The degree of neocollagenesis is proportional to the thermal damage and is better with CO(2) lasers. Their main indication is the correction of photoaged facial skin but they can also be used for corrective dermatology, e.g. for scars and genodermatosis. Results are highly satisfactory but the technique is invasive and the patient experiences a social hindrance of around two weeks. Fractionated techniques treat 25% of the defective skin area at each session in noncontiguous microzones; four sessions are therefore necessary to treat the entire cutaneous surface. The treatment is given under topical anesthesia and is much less invasive, particularly with nonablative fractional laser treatment in which photothermolysis does not penetrate below the epidermis and/or the effects are slight, with no or very little social isolation. However, the results are much less satisfactory than the results of ablative laser and there is no firming effect. Other zones than the face can be treated. With the fractional CO(2) and Erbium ablative lasers, which have multiplied over the past 2 years, the much wider impacts cause perforation of the epidermis and there is a zone of ablation by laser photovaporization, with a zone of thermal damage below. The results are better in correcting photoaging of the face, without, however, achieving the efficacy of ablative lasers, which remain the reference technique. However, the effects are not insignificant, requiring at least 5 days of social isolation.

  20. The Dynamics of Titan's Convective Clouds

    NASA Astrophysics Data System (ADS)

    Rafkin, S. C.

    2012-12-01

    Titan's deep convective clouds are the most dynamic phenomena known to operate within the atmosphere of the moon. Previous studies have focused primarily on the control of these storms by the large scale thermodynamic environment, especially methane abundance, which determines the amount of convective available potential energy (CAPE). This study looks at factors in addition to the thermodynamic environment that may have a first order impact on the evolution and structure of Titan's deep convective clouds. To the extent that thunderstorms on Earth provide a reasonable analog to the storms on Titan, it is well established that CAPE alone is insufficient to determine the structure and behavior of deep convection. Wind shear—both directional and speed—is also known to exert a first order effect. The influence of both CAPE and wind speed shear is typically expressed as the ratio of the two parameters in the form of the Bulk Richardson Number. On Earth, for a fixed value of CAPE, the addition of wind speed shear (i.e., the reduction of the Bulk Richardson Number) will tend to produce storms that are longer lived, tilted upshear with height, and multi-cellular in nature. These multi-cellular storms also tend to be more violent than storms generated in low wind speed shear environments: strong winds and large hail are common. The addition of directional shear (i.e., helicity) can transform the multi-cell storms into single, intense supercell storms. These are the storms associated typically associated with tornadoes. With respect to Titan, if there is a similar dependence on the Bulk Richardson Number, then this would have implications for how long Titan's storms live, how much precipitation they can produce, the area they cover, and the strength and duration of winds. A series of numerical simulations of Titan's deep convective clouds from the Titan Regional Atmospheric Modeling System are presented. A reasonable sweep of the parameter space of CAPE and shear for

  1. OCDR guided laser ablation device

    DOEpatents

    Dasilva, Luiz B.; Colston, Jr., Bill W.; James, Dale L.

    2002-01-01

    A guided laser ablation device. The device includes a mulitmode laser ablation fiber that is surrounded by one or more single mode optical fibers that are used to image in the vicinity of the laser ablation area to prevent tissue damage. The laser ablation device is combined with an optical coherence domain reflectometry (OCDR) unit and with a control unit which initializes the OCDR unit and a high power laser of the ablation device. Data from the OCDR unit is analyzed by the control unit and used to control the high power laser. The OCDR images up to about 3 mm ahead of the ablation surface to enable a user to see sensitive tissue such as a nerve or artery before damaging it by the laser.

  2. Dissolution on Titan and on Earth: Towards the Age of Titan's Karstic-like Landscapes

    NASA Astrophysics Data System (ADS)

    Cornet, T.; Cordier, D.; Le Bahers, T.; Bourgeois, O.; Fleurant, C.; Le Mouelic, S.; Altobelli, N.

    2015-12-01

    Titan's polar surface is dotted with hundreds of lacustrine depressions. Their morphology suggests that their development would be associated to karstic-like processes, involving Titan's liquids (methane, ethane) dissolving the solid surface, presumably composed of organics and ices. In the present work, we test whether or not surface dissolution could be a major landshaping process on Titan using a solutional denudation rates model. The model is based on thermodynamics (solute solubility in solvents) and climatic (temperature, precipitation rates) parameters and has already been used to describe the dissolution of carbonates in karstic areas on Earth. It allows inference of rough formation timescales for topographic depressions of a given depth, developed by chemical erosion only. We computed and compared the denudation rates of pure solid organics in liquid hydrocarbons and of minerals in liquid water over Titan and Earth timescales. We then investigated the denudation rates of superficial organic layers in liquid methane over one Titan year. At this timescale, such a layer on Titan would behave like salts or carbonates on Earth depending on its composition, which means that dissolution processes would likely occur but would be 30 times slower on Titan compared to the Earth due to the seasonality of methane precipitation. Assuming that Titan's past climatic conditions remained close to the present ones, and assuming an average depth of 100 m for Titan's lacustrine depressions, these could have developed in a few tens of millions of years at polar latitudes higher than 70°N and S, and a few hundreds of million years at lower polar latitudes. The ages determined are consistent with the youth of the surface (<1 Gyr) and the repartition of dissolution-related landforms on Titan.

  3. From Titan to the primitive Earth

    NASA Astrophysics Data System (ADS)

    Raulin, F.; Gpcos Team

    Our knowledge of the conditions prevailing in the environment of the primitive Earth is still very limited, due to the lack of geological data. Fortunately, there are a few planetary objects in the solar system which present similarities with our planet, including during its early history. Titan is one of these. With a diameter of more than 5100 km, Titan, the largest moon of Saturn, is also the only one to have a dense atmosphere. This atmosphere, clearly evidenced by the presence of haze layers, extends to approximately 1500 km. Like the Earth, Titan's atmosphere is mainly composed of dinitrogen, N2 . The other main constituents are methane, CH4 , about 1.6% to 2.0% in the stratosphere, as measured by CIRS on Cassini and GC-MS on Huygens and dihydrogen (H2 , approximate 0.1%). With surface temperatures of approximately 94 K, and an average surface pressure of 1.5 bar, Titan's atmosphere is nearly five times denser than the Earth's. Despite of these differences between Titan and the Earth there are several analogies that can be drawn between the two planetary bodies. The first resemblances concern the vertical atmospheric structure. Although Titan is much colder, with a troposphere (˜94-˜70 K), a tropopause (70.4 K) and a stratosphere (˜70-175 K) its atmosphere presents a similar complex structure to that of the Earth. These analogies are linked to the presence in both atmospheres of greenhouse gases: CH4 and H2 on Titan, equivalent respectively to terrestrial condensable H2 O and non-condensable CO2 . In addition the haze particles and clouds in Titan's atmosphere play an antigreenhouse effect similar to that of the terrestrial atmospheric aerosols and clouds. Indeed, methane on Titan seems to play the role of water on the Earth, with a complex cycle, which still has to be understood. The possibility that Titan is covered with hydrocarbon oceans is now ruled out, but it is still possible that Titan's surface include lakes of methane and ethane. Moreover, the

  4. Multiple target laser ablation system

    DOEpatents

    Mashburn, Douglas N.

    1996-01-01

    A laser ablation apparatus and method are provided in which multiple targets consisting of material to be ablated are mounted on a movable support. The material transfer rate is determined for each target material, and these rates are stored in a controller. A position detector determines which target material is in a position to be ablated, and then the controller controls the beam trigger timing and energy level to achieve a desired proportion of each constituent material in the resulting film.

  5. Multiple target laser ablation system

    DOEpatents

    Mashburn, D.N.

    1996-01-09

    A laser ablation apparatus and method are provided in which multiple targets consisting of material to be ablated are mounted on a movable support. The material transfer rate is determined for each target material, and these rates are stored in a controller. A position detector determines which target material is in a position to be ablated, and then the controller controls the beam trigger timing and energy level to achieve a desired proportion of each constituent material in the resulting film. 3 figs.

  6. Diffusion and thermal escape of CH4 and H2 from Titan's upper atmosphere: Direct Monte Carlo simulations

    NASA Astrophysics Data System (ADS)

    Tucker, O. J.; Tenishev, V.; Combi, M. R.; Nagy, A. F.; Johnson, R. E.

    2013-12-01

    We expand on our previous studies using a similar Direct Monte Carlo Simulation (DSMC) technique to examine the role of thermal conduction and escape in Titan's upper atmosphere for comparison to Cassini Ion Neutral Mass Spectrometer (INMS) densities for N2, CH4 and H2 for the T43 encounter. Recent studies have shown the INMS N2 density measurements in Titan's upper atmosphere are indicative of a highly variable thermal structure, however the energy sources and sinks to the atmosphere that result in the large gradients remain unclear (e.g., Snowden et al., 2013a, b). In our previous study (Tucker et al., 2013) we showed that H2 escape from Titan's upper atmosphere adiabatically cools both N2 and CH4 resulting in density profiles that mimic outward flow. Furthermore, we found from steady state calculations that, over the range of temperatures suggested for Titan's upper atmosphere, the H2 densities in our simulations separated from background atmosphere at altitudes lower than in the Cassini data. In this study we include heating in the simulation domain and we model both CH4 and H2 in the background N2 atmosphere. At a lower boundary of the simulation domain, well below the exobase, we will use the INMS density data and a temperature obtained from published results (e.g., Snowden et al., 2013b, Westlake et al., 2011). In the simulation domain we will use typical energy deposition rates suggested for solar UV and precipitating ions from Saturn's magnetosphere into the upper atmosphere (e.g., Johnson et al., 2009), as well as, the heating rates suggested to reproduce the T43 temperature profile in Snowden et al, (2013b). For comparison the heating rates will be used for both steady state and temporal, over 1 Titan day, calculations. Support for this work was provided by grant NNH12ZDA001N-OPR from the NASA ROSES Outer Planets Research Program. Johnson, R.E., 2009. Titan from Cassini Huygens. Mass Loss Processes in Titan's Upper Atmosphere. Springer, New York (Chapter

  7. Titan's upper atmospheric structure and ionospheric composition

    NASA Astrophysics Data System (ADS)

    Westlake, Joseph H.

    This Dissertation investigates the density structure of the neutral upper atmosphere and the composition of the ionosphere of Titan through Cassini observations. The highly extended atmosphere of Titan consists primarily of N2, CH4, and H2. The focus is on data extracted from the Ion and Neutral Mass Spectrometer (INMS) and the Cassini Plasma Spectrometer (CAPS) instruments onboard Cassini. The INMS, which is fundamentally a quadrupole mass spectrometer, measures the abundance of neutral and ion components with masses of 1--8 and 12--99 Da. The CAPS instrument consists of three subsystems of which the Ion Beam Spectrometer (CAPS-IBS) is used in this study to derive mass spectra of thermal ions up to 400 Da. in mass in Titan's ionosphere. From measurements of molecular nitrogen in Titan's upper atmosphere an atmospheric scale height is derived implying an effective temperature. From an analysis of 29 targeted flybys of Titan we find that the thermosphere is isothermal from an altitude of 1050 km to the exobase height with an average effective temperature of 153 K. The scale height, and hence the effective temperature, is found to be highly variable. We assess this variability against the relevant geospatial, solar, and magnetospheric parameters to determine which are highly correlated to the effective temperatures. Titan's thermospheric temperature is found to be controlled by variations in the magnetospheric plasma environment. No correlation is found to exist with respect to geospatial parameters (i.e., latitude or longitude) and anti-correlation is found with solar parameters implying that Titan's nightside is hotter than its dayside. Furthermore, Titan's thermosphere is found to respond to plasma forcings on timescales less than one Titan day. To investigate the composition of Titan's ionosphere we present a 1D photochemical model of Titan's dayside ionosphere constrained by Cassini measurements. We show that the production of the primary products of

  8. Titan's lower troposphere: thermal structure and dynamics

    NASA Astrophysics Data System (ADS)

    Charnay, B.; Lebonnois, S.

    2011-12-01

    A new climate model for Titan's atmosphere has been developed, using the physics of the IPSL Titan 2-dimensional climate model with the current version of the LMDZ General Circulation Model's dynamical core. The GCM covers altitudes from the surface to 500 km with the diurnal cycle and the gravitational tides included. 1. Boundary layer and thermal structure The HASI profile of potential temperature shows a layer at 300 m, an other at 800 m and a slope change at 2 km ([5],[2]). Dune spacing on Titan is consistent with a 2-3 km boundary layer ([3]). We have reproduced this profile (see figure) and interpreted the layer at 300 m as a convective boundary layer, the layer at 800 m is a residual layer corresponding to the maximum diurnal vertical extension of the PBL. We interpret the slope change at 2 km as produced by the seasonal displacement of the ITCZ. This layer traps the circulation in the first two km and is responsible of the dune spacing. Finally we interpret the fog discovered in summer polar region ([1]) has clouds produced by the diurnal cycle of the PBL (as fair weather cumulus on Earth). 2. Surface winds 2.1 Effect of gravitational and thermal tides We analysed tropospheric winds and the influence of both the thermal and the gravitational tides. The impact of gravitational tides on the circulation is extremely small. Thermal tides have a visible effect, though quite tenuous. 2.2 Effect of topography We produced topography maps derived from spherical harmonic interpolation ([6]) on the reference ellipsoid ([4]). Surface temperatures at high altitude appear higher that the ambient air. Vertical air movements produce anabatic winds developing on smooth and long slopes. This could be one of the main causes controlling the direction of surface winds and the direction of dunes. References [1] Brown et al.: Discovery of fog at the south pole of Titan, Astrophys. J. 706 (2009), pp. L110-L113 [2] Griffith et al.: Titan's Tropical Storms in an Evolving Atmosphere

  9. Spacecraft Exploration of Titan and Enceladus

    NASA Astrophysics Data System (ADS)

    Matson, D.; Coustenis, A.; Lunine, J. I.; Lebreton, J.; Reh, K.; Beauchamp, P.; Erd, C.

    2009-12-01

    The future exploration of Titan and Enceladus is very important for planetary science. The study titled Titan Saturn System Mission (TSSM) led to an announcement in which ESA and NASA prioritized future OPF missions, stating that TSSM is planned after EJSM (for details see http://www.lpi.usra.edu/opag/). The TSSM concept consists of an Orbiter that would carry two in situ elements: the Titan Montgolfiere hot air balloon and the Titan Lake Lander. This mission could launch in the 2023-2025 timeframe on a trajectory to arrive ~9 years later and begin a 4-year mission in the Saturnian system. At an appropriate time after arrival at Saturn, the montgolfiere would be delivered to Titan to begin its mission of airborne, scientific observations of Titan from an altitude of about 10 km above the surface. The montgolfiere would have a Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) power system whose waste heat would warm the gas in the balloon, providing buoyancy. It would be designed to survive at least 6-12 months in Titan’s atmosphere. With the predicted winds and weather, it should be possible to circumnavigate the globe! Later, on a subsequent fly-by, the TSSM orbiter would send the Lake Lander to Titan. It would descend through the atmosphere making scientific measurements, much like Huygens did, and then land and float on one of Titan’s seas. This would be its oceanographic phase of making a physical and chemical assessment of the sea. The Lake Lander would operate for 8-10 hours until its batteries become depleted. Following the delivery of the in situ elements, the TSSM orbiter would then explore the Saturn system for two years on a tour that includes in situ sampling of Enceladus’ plumes as well as flybys of Titan. After the Saturn tour, the TSSM orbiter would go into orbit around Titan and carry out a global survey phase. Synergistic observations would be carried out by the TSSM orbiter and the in situ elements. The scientific requirements for

  10. Comparing Earth and Titan's atmospheric inventory

    NASA Astrophysics Data System (ADS)

    Bampasidis, Georgios; Coustenis, Athena; Solomonidou, Anezina; Moussas, Xenophon; Preka-Papadema, Panagiota

    2010-05-01

    Titan is currently the only confirmed exobiotic environment known to us. It is also perhaps the most intriguing object in our Solar System. Our understanding of Titan, and of the kronian system as a whole, has been greatly enhanced by the data returned by the Cassini/Huygens mission since 2004 and still operating on the spot. Thus, we know today that the thick atmosphere layer - covering the satellite's mysterious surface - is essentially made of nitrogen, with small amounts of methane and hydrogen. The combination among these mother molecules produces an exciting organic chemistry in Titan's atmosphere, with hydrocarbons and nitriles (one of the latter, HCN, is a prebiotic molecule). The organic chemistry, climate conditions, meteorology, methane cycle and other aspects of the surface make Titan an extremely important astrobiological place. We will summarize our current understanding of the analogues between Titan and Earth's atmospheres focusing on some compositional and climatological issues. After the Cassini/Huygens mission, there will remain several unanswered questions on the astrobiological aspects of the satellite that will require a future mission with an optimized orbital tour, specific in situ elements and advanced instrumentation, such as the Titan Saturn System Mission (Coustenis et al, 2009; Reh et al., 2009) studied in 2008. The TSSM orbiter with hi-resolution imagers and IR spectrometers onboard and the TSSM Montgolfier with an aerosol analyser and a meteorology package aboard will deeply investigate the Titan organic factory and its atmospheric diversity by performing long-term observations. Definitely, as Titan is a unique earth-like body in the solar system, the long experience of studying the terrestrial atmosphere gives us the tools to unveil the satellite's mysteries. On the other hand, Titan's science will significally contribute to the Earth's atmospheric knowledge, its evolution and chemistry and to the origin of life, as it certainly

  11. ISO observations of Titan with SWS/grating

    NASA Technical Reports Server (NTRS)

    Coustenis, A.; Encrenaz, T.; Salama, A.; Lellouch, E.; Gautier, D.; Kessler, M. F.; deGraauw, T.; Samuelson, R. E.; Bjoraker, G.; Orton, G.

    1997-01-01

    The observations of Titan performed by the Infrared Space Observatory (ISO) short wavelength spectrometer (SWS), in the 2 micrometer to 45 micrometer region using the grating mode, are reported on. Special attention is given to data from Titan concerning 7 micrometer to 45 micrometer spectral resolution. Future work for improving Titan's spectra investigation is suggested.

  12. Organics on Titan : Carbon Rings and Carbon Cycles (Invited)

    NASA Astrophysics Data System (ADS)

    Lorenz, R. D.

    2010-12-01

    ? What are the inscrutably amorphous midlatitude terrains made of ? Is Titan’s bulk crust made of water ice? Only a few places show evidence of water ice bedrock (notably fluvial debris, and the fresh-looking Sinlap ejecta blanket). This may relate to another puzzle - the apparently karstic depressions, many of which are filled with hydrocarbon lakes, found in the polar regions. Low solubility makes etching of hundred-meter deep depressions in ice rather improbable. Perhaps the crust comprises shock-processed organic material from early in Titan’s history, as well as photolysis/radiolysis products forming today. Are the flow-like features detected in a number of places such as Hotei, ‘classical’ ammonia-water cryolavas as claimed, merely geomorphological delusions, or are they some reprocessed organic material heated or squeezed in the interior ? A terrestrial analog might be the salt glaciers of Iran, or in sci-fi the ‘waxworms’ of Titan in Arthur C. Clarke’s ‘Imperial Earth’. Classic cryovolcanism (and impact melt) is of course of interest for the known prebiotic synthesis pathways via hydrolysis of tholins, but some recent work suggests that at least trace prebiotic synthesis may occur in the gas phase via oxygen-bearing molecules sprinkled into the upper atmosphere by ablation of icy meteoroids and O+ ions from Enceladus. In any case, Titan presents us with an abundant and rich inventory of organics.

  13. High Resolution Camera for Mapping Titan Surface

    NASA Technical Reports Server (NTRS)

    Reinhardt, Bianca

    2011-01-01

    Titan, Saturn's largest moon, has a dense atmosphere and is the only object besides Earth to have stable liquids at its surface. The Cassini/Huygens mission has revealed the extraordinary breadth of geological processes shaping its surface. Further study requires high resolution imaging of the surface, which is restrained by light absorption by methane and scattering from aerosols. The Visual and Infrared Mapping Spectrometer (VIMS) onboard the Cassini spacecraft has demonstrated that Titan's surface can be observed within several windows in the near infrared, allowing us to process several regions in order to create a geological map and to determine the morphology. Specular reflections monitored on the lakes of the North Pole show little scattering at 5 microns, which, combined with the present study of Titan's northern pole area, refutes the paradigm that only radar can achieve high resolution mapping of the surface. The present data allowed us to monitor the evolution of lakes, to identify additional lakes at the Northern Pole, to examine Titan's hypothesis of non-synchronous rotation and to analyze the albedo of the North Pole surface. Future missions to Titan could carry a camera with 5 micron detectors and a carbon fiber radiator for weight reduction.

  14. Evaporation of Liquid Hydrocarbon Mixtures on Titan

    NASA Astrophysics Data System (ADS)

    Luspay-Kuti, Adrienn; Chevrier, V. F.; Rivera-Valentin, E. G.; Singh, S.; Roe, L. A.; Wagner, A.

    2013-10-01

    Besides Earth, Titan is the only other known planetary body with proven stable liquids on its surface. The hydrological cycle of these liquid hydrocarbon mixtures is critical in understanding Titan’s atmosphere and surface features. Evaporation of liquid surface bodies has been indirectly observed as shoreline changes from measurements by Cassini ISS and RADAR (Hayes et al. 2011, Icarus 211, 655-671; Turtle et al. 2011, Science 18, 1414-1417.), but the long seasons of Saturn strongly limit the time span of these observations and their validity over the course of an entire Titan year. Using a novel Titan simulation chamber, the evaporation rate of liquid methane and dissolved nitrogen mixture under Titan surface conditions was derived (Luspay-Kuti et al. 2012, GRL 39, L23203), which is especially applicable to low latitude transient liquids. Polar lakes, though, are expected to be composed of a variety of hydrocarbons, primarily a mixture of ethane and methane (e.g. Cordier et al. 2009, ApJL 707, L128-L131). Here we performed laboratory simulations of ethane-methane mixtures with varying mole fraction under conditions suitable for the polar regions of Titan. We will discuss results specifically addressing the evaporation behavior as the solution becomes increasingly ethane dominated, providing quantitative values for the evaporation rate at every step. These laboratory results are relevant to polar lakes, such as Ontario Lacus, and can shed light on their stability.

  15. Impact-induced Climate Change on Titan

    NASA Astrophysics Data System (ADS)

    Zahnle, K. J.; Korycansky, D.

    2012-12-01

    Titan's thick atmosphere and volatile surface cause it to respond to big impacts like the one that produced the prominent Menrva impact basin in a somewhat Earth-like manner. Menrva was big enough to raise the surface temperature by 100 K. If methane in the regolith is generally as abundant as it was at the Huygens landing site, Menrva would have been big enough to double the amount of methane in the atmosphere, The extra methane would have drizzled out of the atmosphere over hundreds of years. Conditions may have been favorable for clathrating volatiles such as ethane. Impacts can also create local crater lakes set in warm ice but these quickly sink below the warm ice; whether the cryptic waters quickly freeze by mixing with the ice crust or whether they long endure under the ice remains a open question. Bigger impacts can create shallow liquid water oceans at the surface. If Titan's crust is made of water ice, the putative Hotei impact (a possible 800-1200 km diameter basin, Soderblom et al 2009) would have raised the average surface temperature to 350-400 K. Water rain would have fallen and global meltwaters would have averaged 50 m to as much as 500 m deep. The meltwaters may not have lasted more than a few decades or centuries at most, but are interesting to consider given Titan's organic wealth. After Menrva impact on Titan After Hotei impact on Titan

  16. Transient features in a Titan sea

    NASA Astrophysics Data System (ADS)

    Hofgartner, J. D.; Hayes, A. G.; Lunine, J. I.; Zebker, H.; Stiles, B. W.; Sotin, C.; Barnes, J. W.; Turtle, E. P.; Baines, K. H.; Brown, R. H.; Buratti, B. J.; Clark, R. N.; Encrenaz, P.; Kirk, R. D.; Le Gall, A.; Lopes, R. M.; Lorenz, R. D.; Malaska, M. J.; Mitchell, K. L.; Nicholson, P. D.; Paillou, P.; Radebaugh, J.; Wall, S. D.; Wood, C.

    2014-07-01

    Titan's surface-atmosphere system bears remarkable similarities to Earth's, the most striking being an active, global methane cycle akin to Earth's water cycle. Like the hydrological cycle of Earth, Titan's seasonal methane cycle is driven by changes in the distribution of solar energy. The Cassini spacecraft, which arrived at Saturn in 2004 in the midst of northern winter and southern summer, has observed surface changes, including shoreline recession, at Titan's south pole and equator. However, active surface processes have yet to be confirmed in the lakes and seas in Titan's north polar region. As the 2017 northern summer solstice approaches, the onset of dynamic phenomena in this region is expected. Here we present the discovery of bright features in recent Cassini RADAR data that appeared in Titan's northern sea, Ligeia Mare, in July 2013 and disappeared in subsequent observations. We suggest that these bright features are best explained by the occurrence of ephemeral phenomena such as surface waves, rising bubbles, and suspended or floating solids. We suggest that our observations are an initial glimpse of dynamic processes that are commencing in the northern lakes and seas as summer nears in the northern hemisphere.

  17. Matricectomy and nail ablation.

    PubMed

    Baran, Robert; Haneke, Eckart

    2002-11-01

    Matricectomy refers to the complete extirpation of the nail matrix, resulting in permanent nail loss. Usually however, matricectomy is only partial, restricted to one or both lateral horns of the matrix. Nail ablation is the definitive removal of the entire nail organ. The most important common denominator in the successful matricectomy is the total removal or destruction of the matrix tissue. Matricectomy may be indicated for the management of onychauxis, onychogryphosis, congenital nail dystrophies, and chronic painful nail, such as recalcitrant ingrown toenail or split within the medial or lateral one-third of the nail.

  18. High temperature ablative foam

    NASA Technical Reports Server (NTRS)

    Liu, Matthew T. (Inventor)

    1992-01-01

    An ablative foam composition is formed of approximately 150 to 250 parts by weight polymeric isocyanate having an isocyanate functionality of 2.6 to 3.2; approximately 15 to 30 parts by weight reactive flame retardant having a hydroxyl number range from 200-260; approximately 10 to 40 parts by weight non-reactive flame retardant; approximately 10 to 40 parts by weight nonhydrolyzable silicone copolymer having a hydroxyl number range from 75-205; and approximately 3 to 16 parts by weight amine initiated polyether resin having an isocyanate functionality greater than or equal to 3.0 and a hydroxyl number range from 400-800.

  19. Long-period librations of Titan

    NASA Astrophysics Data System (ADS)

    Yseboodt, Marie; Van Hoolst, T.

    2013-10-01

    Because of its elliptical orbit around Saturn and its non-spherical mass distribution, Titan has longitudinal librations. Here we study the long-period librations of Titan and include deformation effects and the existence of a subsurface ocean. We take into account the fact that the orbit is not keplerian and has other periodicities than the main period of orbital motion around Saturn due to perturbations by the Sun, other planets and moons (in particular Iapetus). An orbital theory is used to compute the orbital perturbations due to these other bodies. We numerically evaluate the amplitude of the long-period librations for many interior structure models of Titan constrained by the mass, radius and gravity field. Measurements of these librations may give constrains on the interior structure of the icy satellites.

  20. Results from the Huygens probe on Titan

    NASA Astrophysics Data System (ADS)

    Lebreton, Jean-Pierre; Coustenis, Athena; Lunine, Jonathan; Raulin, François; Owen, Tobias; Strobel, Darrell

    2009-06-01

    The Cassini-Huygens mission, comprising the NASA Saturn Orbiter and the ESA Huygens Probe, arrived at Saturn in late June 2004. The Huygens probe descended under parachute in Titan's atmosphere on 14 January 2005, 3 weeks after separation from the Orbiter. We discuss here the breakthroughs that the Huygens probe, in conjunction with the Cassini spacecraft, brought to Titan science. We review the achievements ESA's Huygens probe put forward and the context in which it operated. The findings include new localized information on several aspects of Titan science: the atmospheric structure and chemical composition; the aerosols distribution and content; the surface morphology and composition at the probe's landing site; the winds, the electrical properties, and the implications on the origin and evolution of the satellite.

  1. Percutaneous Ablation in the Kidney

    PubMed Central

    Wood, Bradford J.; Gervais, Debra A.

    2011-01-01

    Percutaneous ablation in the kidney is now performed as a standard therapeutic nephron-sparing option in patients who are poor candidates for resection. Its increasing use has been largely prompted by the rising incidental detection of renal cell carcinomas with cross-sectional imaging and the need to preserve renal function in patients with comorbid conditions, multiple renal cell carcinomas, and/or heritable renal cancer syndromes. Clinical studies to date indicate that radiofrequency ablation and cryoablation are effective therapies with acceptable short- to intermediate-term outcomes and with a low risk in the appropriate setting, with attention to pre-, peri-, and postprocedural detail. The results following percutaneous radiofrequency ablation and cryoablation in the treatment of renal cell carcinoma are reviewed in this article, including those of several larger scale studies of ablation of T1a tumors. Clinical and technical considerations unique to ablation in the kidney are presented, and potential complications are discussed. © RSNA, 2011 PMID:22012904

  2. Chapman Solar Zenith Angle variations at Titan

    NASA Astrophysics Data System (ADS)

    Royer, Emilie M.; Ajello, Joseph; Holsclaw, Gregory; West, Robert; Esposito, Larry W.; Bradley, Eric Todd

    2016-10-01

    Solar XUV photons and magnetospheric particles are the two main sources contributing to the airglow in the Titan's upper atmosphere. We are focusing here on the solar XUV photons and how they influence the airglow intensity. The Cassini-UVIS observations analyzed in this study consist each in a partial scan of Titan, while the center of the detector stays approximately at the same location on Titan's disk. We used observations from 2008 to 2012, which allow for a wide range of Solar Zenith Angle (SZA). Spectra from 800 km to 1200 km of altitude have been corrected from the solar spectrum using TIMED/SEE data. We observe that the airglow intensity varies as a function of the SZA and follows a Chapman curve. Three SZA regions are identified: the sunlit region ranging from 0 to 50 degrees. In this region, the intensity of the airglow increases, while the SZA decreases. Between SZA 50 and 100 degrees, the airglow intensity decreases from it maximum to its minimum. In this transition region the upper atmosphere of Titan changes from being totally sunlit to being in the shadow of the moon. For SZA 100 to 180 degrees, we observe a constant airglow intensity close to zero. The behavior of the airglow is also similar to the behavior of the electron density as a function of the SZA as observed by Ågren at al (2009). Both variables exhibit a decrease intensity with increasing SZA. The goal of this study is to understand such correlation. We demonstrate the importance of the solar XUV photons contribution to the Titan airglow and prove that the strongest contribution to the Titan dayglow occurs by solar fluorescence rather than the particle impact that predominates at night.

  3. Tidal Response of Titan's Lakes and Seas

    NASA Astrophysics Data System (ADS)

    Karatekin, O.; Demain, C.; Deleersnijder, E.

    2011-12-01

    The Cassini spacecraft has revealed a vast set of lakes/seas filled or partially filled with liquid hydrocarbons and empty lake basins in the high latitudes of Titan. The seas and lakes of Titan provide an opportunity to explore an exciting aqueous environment whose characteristics are very different from what we know on Earth. The lakes appear in various shapes and sizes and are filled with liquid hydrocarbons, primarily methane and ethane. Recently, the Cassini spacecraft provided observations suggesting for the first time temporal variations in lake surfaces. The variation in the shorelines can be explained by different hypothesis including evaporation and tides. During Titan's 16 day orbital period around Saturn, the time-dependent tidal response of the lakes may affect the shorelines. Although the estimated tidal amplitudes by theoretical consideration yield smaller than the observed depth changes on Ontario Lacus, tides can have more significant effects of other lakes/seas with tidal amplitudes up to several meters. In the present study, besides Ontario Lacus we also consider Ligeia Mare, one of three large methane seas discovered by Cassini in the northern hemisphere of Titan and the target for the discovery mission of Titan Mare Explorer (TiME). The tidal response of Titan's lakes an seas are investigated by means of two- dimensional nonlinear shallow water equations The governing partial differential equations on the sphere are solved using SLIM (Second-generation Louvain- la- Neuve Ice-Ocean Model - http://www.climate.be/SLIM). SLIM is a hydrodynamical model based on finite element method. As all general circulation models, it uses primitive variables as prognostic quantities. Partial differential equations are discretized on curved surfaces using triangular meshes. The mesh is generated from recursive subdivisions of the faces of an icosahedron using GMSH software.. The code has a wetting-drying algorithm. The simulations can take into account several

  4. TITAN'S TRANSPORT-DRIVEN METHANE CYCLE

    SciTech Connect

    Mitchell, Jonathan L.

    2012-09-10

    The mechanisms behind the occurrence of large cloud outbursts and precipitation on Titan have been disputed. A global- and annual-mean estimate of surface fluxes indicated only 1% of the insolation, or {approx}0.04 W m{sup -2}, is exchanged as sensible and/or latent fluxes. Since these fluxes are responsible for driving atmospheric convection, it has been argued that moist convection should be quite rare and precipitation even rarer, even if evaporation globally dominates the surface-atmosphere energy exchange. In contrast, climate simulations indicate substantial cloud formation and/or precipitation. We argue that the top-of-atmosphere (TOA) radiative imbalance is diagnostic of horizontal heat transport by Titan's atmosphere, and thus constrains the strength of the methane cycle. Simple calculations show the TOA radiative imbalance is {approx}0.5-1 W m{sup -2} in Titan's equatorial region, which implies 2-3 MW of latitudinal heat transport by the atmosphere. Our simulation of Titan's climate suggests this transport may occur primarily as latent heat, with net evaporation at the equator and net accumulation at higher latitudes. Thus, the methane cycle could be 10-20 times previous estimates. Opposing seasonal transport at solstices, compensation by sensible heat transport, and focusing of precipitation by large-scale dynamics could further enhance the local, instantaneous strength of Titan's methane cycle by a factor of several. A limited supply of surface liquids in regions of large surface radiative imbalance may throttle the methane cycle, and if so, we predict more frequent large storms over the lakes district during Titan's northern summer.

  5. Cassini radar views the surface of Titan

    NASA Technical Reports Server (NTRS)

    Elachi, C.; Wall, S.; Allison, M.; Anderson, Y.; Boehmer, R.; Callahan, P.; Encrenaz, P.; Flamini, E.; Franceschetti, G.; Gim, Y.; Hamilton, G.; Hensley, S.; Janssen, M.; Johnson, W.; Kelleher, K.; Kirk, R.; Lopes, R.; Lorenz, R.; Lunine, J.; Muhleman, D.; Ostro, S.; Paganelli, F.; Picardi, G.; Posa, F.; Roth, L.

    2005-01-01

    The Cassini Titan Radar Mapper imaged about 1% of Titan's surface at a resolution of approximately 0.5 kilometer, and larger areas of the globe in lower resolution modes. The images reveal a complex surface, with areas of low relief and a variety of geologic features suggestive of dome-like volcanic constructs, flows, and sinuous channels. The surface appears to be young, with few impact craters. Scattering and dielectric properties are consistent with porous ice or organics. Dark patches in the radar images show high brightness temperatures and high emissivity and are consistent with frozen hydrocarbons.

  6. The latitudinal distribution of clouds on Titan.

    PubMed

    Rannou, P; Montmessin, F; Hourdin, F; Lebonnois, S

    2006-01-13

    Clouds have been observed recently on Titan, through the thick haze, using near-infrared spectroscopy and images near the south pole and in temperate regions near 40 degrees S. Recent telescope and Cassini orbiter observations are now providing an insight into cloud climatology. To study clouds, we have developed a general circulation model of Titan that includes cloud microphysics. We identify and explain the formation of several types of ethane and methane clouds, including south polar clouds and sporadic clouds in temperate regions and especially at 40 degrees in the summer hemisphere. The locations, frequencies, and composition of these cloud types are essentially explained by the large-scale circulation.

  7. Cassini radar views the surface of Titan

    USGS Publications Warehouse

    Elachi, C.; Wall, S.; Allison, M.; Anderson, Y.; Boehmer, R.; Callahan, P.; Encrenaz, P.; Flamini, E.; Franceschetti, G.; Gim, Y.; Hamilton, G.; Hensley, S.; Janssen, M.; Johnson, W.; Kelleher, K.; Kirk, R.; Lopes, R.; Lorenz, R.; Lunine, J.; Muhleman, D.; Ostro, S.; Paganelli, F.; Picardi, G.; Posa, F.; Roth, L.; Seu, R.; Shaffer, S.; Soderblom, L.; Stiles, B.; Stofan, E.; Vetrella, S.; West, R.; Wood, C.; Wye, L.; Zebker, H.

    2005-01-01

    The Cassini Titan Radar Mapper imaged about 1% of Titan's surface at a resolution of ???0.5 kilometer, and larger areas of the globe in lower resolution modes. The images reveal a complex surface, with areas of low relief and a variety of geologic features suggestive of dome-like volcanic constructs, flows, and sinuous channels. The surface appears to be young, with few impact craters. Scattering and dielectric properties are consistent with porous ice or organics. Dark patches in the radar images show high brightness temperatures and high emissivity and are consistent with frozen hydrocarbons.

  8. Composition of Titan's surface from Cassini VIMS

    USGS Publications Warehouse

    McCord, T.B.; Hansen, G.B.; Buratti, B.J.; Clark, R.N.; Cruikshank, D.P.; D'Aversa, E.; Griffith, C.A.; Baines, E.K.H.; Brown, R.H.; Dalle, Ore C.M.; Filacchione, G.; Formisano, V.; Hibbitts, C.A.; Jaumann, R.; Lunine, J.I.; Nelson, R.M.; Sotin, C.

    2006-01-01

    Titan's bulk density along with Solar System formation models indicates considerable water as well as silicates as its major constituents. This satellite's dense atmosphere of nitrogen with methane is unique. Deposits or even oceans of organic compounds have been suggested to exist on Titan's solid surface due to UV-induced photochemistry in the atmosphere. Thus, the composition of the surface is a major piece of evidence needed to determine Titan's history. However, studies of the surface are hindered by the thick, absorbing, hazy and in some places cloudy atmosphere. Ground-based telescope investigations of the integral disk of Titan attempted to observe the surface albedo in spectral windows between methane absorptions by calculating and removing the haze effects. Their results were reported to be consistent with water ice on the surface that is contaminated with a small amount of dark material, perhaps organic material like tholin. We analyze here the recent Cassini Mission's visual and infrared mapping spectrometer (VIMS) observations that resolve regions on Titan. VIMS is able to see surface features and shows that there are spectral and therefore likely compositional units. By several methods, spectral albedo estimates within methane absorption windows between 0.75 and 5 ??m were obtained for different surface units using VIMS image cubes from the Cassini-Huygens Titan Ta encounter. Of the spots studied, there appears to be two compositional classes present that are associated with the lower albedo and the higher albedo materials, with some variety among the brighter regions. These were compared with spectra of several different candidate materials. Our results show that the spectrum of water ice contaminated with a darker material matches the reflectance of the lower albedo Titan regions if the spectral slope from 2.71 to 2.79 ??m in the poorly understood 2.8-??m methane window is ignored. The spectra for brighter regions are not matched by the spectrum of

  9. Cryovolcanism on Titan and Enceladus

    NASA Astrophysics Data System (ADS)

    Sotin, C.

    2008-12-01

    of CO or CO2 [Matson et al., Icarus, 2007]. On Titan, the SAR (Synthetic Aperture Radar) and the VIMS (Visual and Infrared Mapping Spectrometer) images suggest that several morphological features could be formed by cryovolcanic activity [Sotin et al., Nature, 2005; Barnes et al., GRL, 2006; Lopes et al., Icarus, 2007]. Such volcanism would explain the recent release of methane and its presence in the atmosphere where its lifetime is a few tens of millions of years. In order to link thermal evolution models and cryovolcanic models, it is necessary to have laboratory data that describe the melting temperature of different kinds of ices including clathrate hydrates containing ammonia, methane, nitrogen and other volatiles. Since the melting temperature of ammonia is small compared to that of water ice, it is a good candidate for explaining flow features seen on Titan's surface. However, the presence of an ocean at depth makes unlikely the presence of ammonia in the icy crust. More sophisticated models must be found with species such as methane and CO2. This work has been carried out at the JPL, Caltech, under contract with NASA.

  10. Huygens GCMS Results from Titan

    NASA Technical Reports Server (NTRS)

    Niemann, Hasso B.; Demick, Jaime; Kasprzak, Wayne; Atreya, Sushil; Owen, Tobias

    2007-01-01

    The Huygens Probe executed a successful entry, descent and impact on the Saturnian moon of Titan on January 14, 2005. The Gas Chromatograph Mass Spectrometer (GCMS) instrument conducted isotopic and compositional measurements throughout the two and one half hour descent from 146 km altitude, and on the surface for 69 minutes until loss of signal from the orbiting Cassini spacecraft. The GCMS incorporated a quadrupole mass filter with a secondary electron multiplier detection system. The gas sampling system provided continuous direct atmospheric composition measurements and batch sampling through three gas chromatographic (GC) columns, a chemical scrubber and a hydrocarbon enrichment cell. The GCMS gas inlet was heated to prevent condensation, and to evaporate volatiles from the surface after impact. Data products from the GCMS included altitude profiles of the major atmospheric constituents dinitrogen (N2) and methane (CH4), isotope ratios of 14N/15N, 12C/13C, and D/H, mole fractions of radiogenic argon (40Ar) and primordial argon (36Ar), and upper limits on the mole fractions of neon, krypton and xenon, which were found to be absent. Surface measurements confirmed the presence of ethane (C2H6) and cyanogen (C2N2). Later data products expanded atmospheric profiles to include the surface response of C2N2. C2H6, acetylene (C2H2), and carbon dioxide (CO2). More recent results include the profiles of benzene (C6H6) and molecular hydrogen (H2). The GCMS data are being further analyzed to obtain higher precision results and to identify other trace species ion the atmosphere and evaporating from the surface.

  11. Cassini/Titan-4 Acoustic Blanket Development and Testing

    NASA Technical Reports Server (NTRS)

    Hughes, William O.; McNelis, Anne M.

    1996-01-01

    NASA Lewis Research Center recently led a multi-organizational effort to develop and test verify new acoustic blankets. These blankets support NASA's goal in reducing the Titan-4 payload fairing internal acoustic environment to allowable levels for the Cassini spacecraft. To accomplish this goal a two phase acoustic test program was utilized. Phase One consisted of testing numerous blanket designs in a flat panel configuration. Phase Two consisted of testing the most promising designs out of Phase One in a full scale cylindrical payload fairing. This paper will summarize this highly successful test program by providing the rationale and results for each test phase, the impacts of this testing on the Cassini mission, as well as providing some general information on blanket designs.

  12. Heavy Ion Formation in Titan's Ionosphere: Magnetospheric Introduction of Free Oxygen and Source of Titan's Aerosols?

    NASA Technical Reports Server (NTRS)

    Sittler, E. C., Jr.; Hartle, R. E.; Cooper, J. F.; Johnson, R. E.; Coates, A.; dePater, imke; Strom, Daphne; Simoes, F.; Steele, A.; Robb, F.

    2007-01-01

    With the recent discovery of heavy ions, positive and negative, by the Cassini Plasma Spectrometer (CAPS) instrument in Titan's ionosphere, it reveals new possibilities for aerosol formation at Titan and the introduction of free oxygen to the aerosol chemistry from Saturn's magnetosphere with Enceladus as the primary oxygen source. One can estimate whether the heavy ions in the ionosphere are of sufficient number to account for all the aerosols, under what conditions are favorable for heavy ion formation and how they are introduced as seed particles deeper in Titan's atmosphere where the aerosols form and eventually find themselves on Titan's surface where unknown chemical processes can take place. Finally, what are the possibilities with regard to their chemistry on the surface with some free oxygen present in their seed particles?

  13. Thermal response and ablation characteristics of light weight ceramic ablators

    NASA Technical Reports Server (NTRS)

    Tran, Huy K.; Rasky, Daniel J.; Esfahani, Lili

    1993-01-01

    An account is given of the thermal performance and ablation characteristics of the NASA-Ames Lightweight Ceramic Ablators (LCAs) in supersonic, high-enthalpy convective environments, which use low density ceramic or carbon fiber matrices as substrates for main structural support, with organic resin fillers. LCA densities are in the 0.224-1.282 g/cu cm range. In-depth temperature data have been obtained to determine thermal penetration depths and conductivity. The addition of SiC and PPMA is noted to significantly improve the ablation performance of LCAs with silica substrates. Carbon-based LCAs are the most mass-efficient at high flux levels.

  14. The Huygens Doppler Wind Experiment: Results from Titan

    NASA Astrophysics Data System (ADS)

    Folkner, W. M.; Bird, M. K.; Dutta-Roy, R.; Allison, M.; Asmar, S. W.; Atkinson, D. H.; Edenhofer, P.; Plettemeier, D.; Tyler, L. H.; Preston, R. A.; Gurvits, L.

    2005-05-01

    The ESA Huygens Probe entered and descended for nearly 2.5 hours through the atmosphere of Titan on 14 January 2005. Huygens survived impact on the surface and continued its telemetry broadcast to the NASA Cassini spacecraft on two separate radio links, denoted Channels A and B, respectively, for an additional 1.2 hours. The instrumentation for the Huygens Doppler Wind Experiment (DWE) consisting of two Ultra-Stable Oscillators in the transmitter (TUSO) and receiver (RUSO), were implemented only in Channel A. Whereas Channel B functioned flawlessly during the entire mission, the receiver for Channel A was never able to lock onto the Huygens signal because the DWE-RUSO had not been properly programmed into the critical probe radio relay sequence. All data on Channel A, including the DWE measurements and probe telemetry, were thus lost. In spite of this setback, the Channel A signal was successfully received at many radio telescopes on Earth. The precision of these Doppler measurements, considered as an aggregate, is roughly equivalent to that which had been foreseen from the measurements on board Cassini. We present an overview of the DWE ground-based observations and the Titan wind profile derived from them.

  15. Safety evaluation of RTG launches aboard Titan IV launch vehicles

    SciTech Connect

    Rosko, R.J.; Loughin, S.

    1997-01-01

    The analytical tool used to evaluate accidents aboard a Titan IV launch vehicle involving a Radioisotope Thermoelectric Generator (RTG) is discussed. The Launch Accident Scenario Evaluation Program-Titan IV version (LASEP-T) uses a Monte Carlo approach to determine the response of an RTG to various threatening environments. The threatening environments arise from a complex interplay of probabilistic and deterministic processes, and are therefore parameterized by a set of random variables with probability distributions. The assessment of the RTG response to a given environment is based on both empirical data and theoretical modeling. Imbedding detailed, complex response models into the LASEP-T calculation was not practical. Simpler response models have been constructed to capture both the inherent variability due to the phenomenology of the accident scenario along with the uncertainty of predicting response behavior. The treatment of variability and uncertainty as it pertains to the launch accident evaluation of RTG response will be discussed. {copyright} {ital 1997 American Institute of Physics.}

  16. Epicardial Ablation of Ventricular Tachycardia

    PubMed Central

    Tung, Roderick; Shivkumar, Kalyanam

    2015-01-01

    Epicardial mapping and ablation via a percutaneous subxiphoid technique has been instrumental in improving the working understanding of complex myocardial scars in various arrhythmogenic substrates. Endocardial ablation alone may not be sufficient in patients with ischemic cardiomyopathy, dilated cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, hypertrophic cardiomyopathy, and Chagas disease to prevent recurrent ventricular tachycardia. Multiple observational studies have demonstrated greater freedom from recurrence with adjunctive epicardial ablation compared with endocardial ablation alone. While epicardial ablation is performed predominantly at tertiary referral centers, knowledge of the technical approach, clinical indications, and potential complications is imperative to maximizing clinical success and patient safety. In 1996, Sosa and colleagues modified the pericardiocentesis technique to enable percutaneous access to the pericardial space for mapping and catheter ablation of ventricular tachycardia.1 Originally developed for patients with epicardial scarring due to chagasic cardiomyopathy and patients with ischemic cardiomyopathy refractory to endocardial ablationm,2,3 this approach has since become an essential part of the armamentarium for the treatment of ventricular tachycardia. Myocardial scars are three-dimensionally complex with varying degrees of transmurality, and the ability to map and ablate the epicardial surface has contributed to a greater understanding of scar-related VT in postinfarction cardiomyopathy and nonischemic substrates including idiopathic dilated cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, hypertrophic cardiomyopathy, and chagasic cardiomyopathy. In this review, we highlight the percutaneous approach and discuss clinical indications and potential complications. PMID:26306131

  17. Cryovolcanic features on Titan's surface as revealed by the Cassini Titan Radar Mapper

    USGS Publications Warehouse

    Lopes, R.M.C.; Mitchell, K.L.; Stofan, E.R.; Lunine, J.I.; Lorenz, R.; Paganelli, F.; Kirk, R.L.; Wood, C.A.; Wall, S.D.; Robshaw, L.E.; Fortes, A.D.; Neish, C.D.; Radebaugh, J.; Reffet, E.; Ostro, S.J.; Elachi, C.; Allison, M.D.; Anderson, Y.; Boehmer, R.; Boubin, G.; Callahan, P.; Encrenaz, P.; Flamini, E.; Francescetti, G.; Gim, Y.; Hamilton, G.; Hensley, S.; Janssen, M.A.; Johnson, W.T.K.; Kelleher, K.; Muhleman, D.O.; Ori, G.; Orosei, R.; Picardi, G.; Posa, F.; Roth, L.E.; Seu, R.; Shaffer, S.; Soderblom, L.A.; Stiles, B.; Vetrella, S.; West, R.D.; Wye, L.; Zebker, H.A.

    2007-01-01

    The Cassini Titan Radar Mapper obtained Synthetic Aperture Radar images of Titan's surface during four fly-bys during the mission's first year. These images show that Titan's surface is very complex geologically, showing evidence of major planetary geologic processes, including cryovolcanism. This paper discusses the variety of cryovolcanic features identified from SAR images, their possible origin, and their geologic context. The features which we identify as cryovolcanic in origin include a large (180 km diameter) volcanic construct (dome or shield), several extensive flows, and three calderas which appear to be the source of flows. The composition of the cryomagma on Titan is still unknown, but constraints on rheological properties can be estimated using flow thickness. Rheological properties of one flow were estimated and appear inconsistent with ammonia-water slurries, and possibly more consistent with ammonia-water-methanol slurries. The extent of cryovolcanism on Titan is still not known, as only a small fraction of the surface has been imaged at sufficient resolution. Energetic considerations suggest that cryovolcanism may have been a dominant process in the resurfacing of Titan. ?? 2006 Elsevier Inc.

  18. [New techniques of tumor ablation (microwaves, electroporation)].

    PubMed

    de Baere, T

    2011-09-01

    Since the introduction of radiofrequency tumor ablation of liver tumors in the late 1990s, local destructive therapies have been applied to lung, renal and bone lesions. In addition, new techniques have been introduced to compensate for the limitations of radiofrequency ablation, namely the reduced rate of complete ablation for tumors larger than 3 cm and tumors near vessels larger than 3 mm. Microwave ablation is currently evolving rapidly. While it is a technique based on thermal ablation similar to radiofrequency ablation, there are significant differences between both techniques. Electroporation, of interest because of the non-thermal nature of the ablation process, also is under evaluation.

  19. Ion Escape from the Ionosphere of Titan

    NASA Technical Reports Server (NTRS)

    Hartle, R.; Sittler, E.; Lipatov, A.

    2008-01-01

    Ions have been observed to flow away from Titan along its induced magnetic tail by the Plasma Science Instrument (PLS) on Voyager 1 and the Cassini Plasma Spectrometer (CAPS) on Cassini. In both cases, the ions have been inferred to be of ionospheric origin. Recent plasma measurements made at another unmagnetized body, Venus, have also observed similar flow in its magnetic tail. Much earlier, the possibility of such flow was inferred when ionospheric measurements made from the Pioneer Venus Orbiter (PVO) were used to derive upward flow and acceleration of H(+), D(+) and O(+) within the nightside ionosphere of Venus. The measurements revealed that the polarization electric field in the ionosphere produced the principal upward force on these light ions. The resulting vertical flow of H(+) and D(+) was found to be the dominant escape mechanism of hydrogen and deuterium, corresponding to loss rates consistent with large oceans in early Venus. Other electrodynamic forces were unimportant because the plasma beta in the nightside ionosphere of Venus is much greater than one. Although the plasma beta is also greater than one on Titan, ion acceleration is expected to be more complex, especially because the subsolar point and the subflow points can be 180 degrees apart. Following what we learned at Venus, upward acceleration of light ions by the polarization electric field opposing gravity in the ionosphere of Titan will be described. Additional electrodynamic forces resulting from the interaction of Saturn's magnetosphere with Titan's ionosphere will be examined using a recent hybrid model.

  20. TandEM: Titan and Enceladus mission

    USGS Publications Warehouse

    Coustenis, A.; Atreya, S.K.; Balint, T.; Brown, R.H.; Dougherty, M.K.; Ferri, F.; Fulchignoni, M.; Gautier, D.; Gowen, R.A.; Griffith, C.A.; Gurvits, L.I.; Jaumann, R.; Langevin, Y.; Leese, M.R.; Lunine, J.I.; McKay, C.P.; Moussas, X.; Muller-Wodarg, I.; Neubauer, F.; Owen, T.C.; Raulin, F.; Sittler, E.C.; Sohl, F.; Sotin, C.; Tobie, G.; Tokano, T.; Turtle, E.P.; Wahlund, J.-E.; Waite, J.H.; Baines, K.H.; Blamont, J.; Coates, A.J.; Dandouras, I.; Krimigis, T.; Lellouch, E.; Lorenz, R.D.; Morse, A.; Porco, C.C.; Hirtzig, M.; Saur, J.; Spilker, T.; Zarnecki, J.C.; Choi, E.; Achilleos, N.; Amils, R.; Annan, P.; Atkinson, D.H.; Benilan, Y.; Bertucci, C.; Bezard, B.; Bjoraker, G.L.; Blanc, M.; Boireau, L.; Bouman, J.; Cabane, M.; Capria, M.T.; Chassefiere, E.; Coll, P.; Combes, M.; Cooper, J.F.; Coradini, A.; Crary, F.; Cravens, T.; Daglis, I.A.; de Angelis, E.; De Bergh, C.; de Pater, I.; Dunford, C.; Durry, G.; Dutuit, O.; Fairbrother, D.; Flasar, F.M.; Fortes, A.D.; Frampton, R.; Fujimoto, M.; Galand, M.; Grasset, O.; Grott, M.; Haltigin, T.; Herique, A.; Hersant, F.; Hussmann, H.; Ip, W.; Johnson, R.; Kallio, E.; Kempf, S.; Knapmeyer, M.; Kofman, W.; Koop, R.; Kostiuk, T.; Krupp, N.; Kuppers, M.; Lammer, H.; Lara, L.-M.; Lavvas, P.; Le, Mouelic S.; Lebonnois, S.; Ledvina, S.; Li, J.; Livengood, T.A.; Lopes, R.M.; Lopez-Moreno, J. -J.; Luz, D.; Mahaffy, P.R.; Mall, U.; Martinez-Frias, J.; Marty, B.; McCord, T.; Salvan, C.M.; Milillo, A.; Mitchell, D.G.; Modolo, R.; Mousis, O.; Nakamura, M.; Neish, C.D.; Nixon, C.A.; Mvondo, D.N.; Orton, G.; Paetzold, M.; Pitman, J.; Pogrebenko, S.; Pollard, W.; Prieto-Ballesteros, O.; Rannou, P.; Reh, K.; Richter, L.; Robb, F.T.; Rodrigo, R.; Rodriguez, S.; Romani, P.; Bermejo, M.R.; Sarris, E.T.; Schenk, P.; Schmitt, B.; Schmitz, N.; Schulze-Makuch, D.; Schwingenschuh, K.; Selig, A.; Sicardy, B.; Soderblom, L.; Spilker, L.J.; Stam, D.; Steele, A.; Stephan, K.; Strobel, D.F.; Szego, K.; Szopa,

    2009-01-01

    TandEM was proposed as an L-class (large) mission in response to ESA's Cosmic Vision 2015-2025 Call, and accepted for further studies, with the goal of exploring Titan and Enceladus. The mission concept is to perform in situ investigations of two worlds tied together by location and properties, whose remarkable natures have been partly revealed by the ongoing Cassini-Huygens mission. These bodies still hold mysteries requiring a complete exploration using a variety of vehicles and instruments. TandEM is an ambitious mission because its targets are two of the most exciting and challenging bodies in the Solar System. It is designed to build on but exceed the scientific and technological accomplishments of the Cassini-Huygens mission, exploring Titan and Enceladus in ways that are not currently possible (full close-up and in situ coverage over long periods of time). In the current mission architecture, TandEM proposes to deliver two medium-sized spacecraft to the Saturnian system. One spacecraft would be an orbiter with a large host of instruments which would perform several Enceladus flybys and deliver penetrators to its surface before going into a dedicated orbit around Titan alone, while the other spacecraft would carry the Titan in situ investigation components, i.e. a hot-air balloon (Montgolfi??re) and possibly several landing probes to be delivered through the atmosphere. ?? Springer Science + Business Media B.V. 2008.

  1. Mountains on Titan observed by Cassini Radar

    USGS Publications Warehouse

    Radebaugh, J.; Lorenz, R.D.; Kirk, R.L.; Lunine, J.I.; Stofan, E.R.; Lopes, R.M.C.; Wall, S.D.

    2007-01-01

    The Cassini Titan Radar mapper has observed elevated blocks and ridge-forming block chains on Saturn's moon Titan demonstrating high topography we term "mountains." Summit flanks measured from the T3 (February 2005) and T8 (October 2005) flybys have a mean maximum slope of 37?? and total elevations up to 1930 m as derived from a shape-from-shading model corrected for the probable effects of image resolution. Mountain peak morphologies and surrounding, diffuse blankets give evidence that erosion has acted upon these features, perhaps in the form of fluvial runoff. Possible formation mechanisms for these mountains include crustal compressional tectonism and upthrusting of blocks, extensional tectonism and formation of horst-and-graben, deposition as blocks of impact ejecta, or dissection and erosion of a preexisting layer of material. All above processes may be at work, given the diversity of geology evident across Titan's surface. Comparisons of mountain and blanket volumes and erosion rate estimates for Titan provide a typical mountain age as young as 20-100 million years. ?? 2007 Elsevier Inc. All rights reserved.

  2. The occultation of 28 SGR by Titan

    NASA Astrophysics Data System (ADS)

    Hubbard, W. B.; Sicardy, B.; Miles, R.; Hollis, A. J.; Forrest, R. W.; Nicolson, I. K. M.; Appleby, G.; Beisker, W.; Bittner, C.; Bode, H.-J.; Bruns, M.; Denzau, H.; Nezel, M.; Riedel, E.; Struckmann, H.; Arlot, J. E.; Roques, F.; Sevre, F.; Thuillot, W.; Hoffmann, M.; Geyer, E. H.; Buil, C.; Colas, F.; Lecacheux, J.; Klotz, A.; Thouvenot, E.; Vidal, J. L.; Carreira, E.; Rossi, F.; Blanco, C.; Cristaldi, S.; Nevo, Y.; Reitsema, H. J.; Brosch, N.; Cernis, K.; Zdanavicius, K.; Wasserman, L. H.; Hunten, D. M.; Gautier, D.; Lellouch, E.; Yelle, R. V.; Rizk, B.; Flasar, F. M.; Porco, C. C.; Toublanc, D.; Corugedo, G.

    1993-03-01

    We present a comprehensive analysis of data obtained during the 1989 July 3 occultation of 28 Sgr by Titan. The data set includes 23 lightcurves from 15 separate stations, spanning wavelengths from 0.36 to 0.89 micron. A detailed model of the structure of Titan's atmosphere in the altitude range 250 to 450 km is developed, giving the distribution of temperature, pressure, haze optical depth, and zonal wind velocity as a function of altitude and latitude. Haze layers detected in Titan's stratosphere are about one scale height higher than inferred from Voyager data, and show a wavelength dependence indicative of particle sizes on the order of 0.1 micron. A marked north-south dichotomy in haze density is observed with a transition to lower density south of about -20 deg latitude. Zonal wind speeds are inferred from global distortions from spherical symmetry and are of the order of 100 m/s with significant increase toward higher latitudes. Titan's high atmosphere shows substantial axial symmetry; the position angle of the symmetry axis is equal to the position angle of Saturn's spin axis to within about 1 deg.

  3. Imaging of Titan from the Cassini spacecraft.

    PubMed

    Porco, Carolyn C; Baker, Emily; Barbara, John; Beurle, Kevin; Brahic, Andre; Burns, Joseph A; Charnoz, Sebastien; Cooper, Nick; Dawson, Douglas D; Del Genio, Anthony D; Denk, Tilmann; Dones, Luke; Dyudina, Ulyana; Evans, Michael W; Fussner, Stephanie; Giese, Bernd; Grazier, Kevin; Helfenstein, Paul; Ingersoll, Andrew P; Jacobson, Robert A; Johnson, Torrence V; McEwen, Alfred; Murray, Carl D; Neukum, Gerhard; Owen, William M; Perry, Jason; Roatsch, Thomas; Spitale, Joseph; Squyres, Steven; Thomas, Peter; Tiscareno, Matthew; Turtle, Elizabeth P; Vasavada, Ashwin R; Veverka, Joseph; Wagner, Roland; West, Robert

    2005-03-10

    Titan, the largest moon of Saturn, is the only satellite in the Solar System with a substantial atmosphere. The atmosphere is poorly understood and obscures the surface, leading to intense speculation about Titan's nature. Here we present observations of Titan from the imaging science experiment onboard the Cassini spacecraft that address some of these issues. The images reveal intricate surface albedo features that suggest aeolian, tectonic and fluvial processes; they also show a few circular features that could be impact structures. These observations imply that substantial surface modification has occurred over Titan's history. We have not directly detected liquids on the surface to date. Convective clouds are found to be common near the south pole, and the motion of mid-latitude clouds consistently indicates eastward winds, from which we infer that the troposphere is rotating faster than the surface. A detached haze at an altitude of 500 km is 150-200 km higher than that observed by Voyager, and more tenuous haze layers are also resolved.

  4. Characteristics and variability of Titan's magnetic environment.

    PubMed

    Bertucci, César L

    2009-02-28

    The structure and variability of Saturn's magnetic field in the vicinity of Titan's orbit is studied. In the dawn magnetosphere, the magnetic field presents a significant radial component directed towards Saturn, suggesting that Titan is usually located below the planet's warped and dynamic magnetodisc. Also, a non-negligible component along the co-rotation direction suggests that Saturn's magnetic field lines close to the magnetodisc are being swept back from their respective magnetic meridians. In the noon sector, Titan seems to be closer to the magnetodisc central current sheet, as the field lines in this region seem to be more dipolar. The distance between the central current sheet and Titan depends mainly on the solar wind pressure. Also, delta|B|/|B| approximately 0.5 amplitude waveforms at periods close to Saturn's kilometric radiation period are present in the background magnetic field. This modulation in the field is ubiquitous in Saturn's magnetosphere and associated with the presence of a rotating asymmetry in the planet's magnetic field. PMID:19073462

  5. Low-Latitude Ethane Rain on Titan

    NASA Technical Reports Server (NTRS)

    Dalba, Paul A.; Buratti, Bonnie J.; Brown, R. H.; Barnes, J. W.; Baines, K. H.; Sotin, C.; Clark, R. N.; Lawrence, K. J.; Nicholson, P. D.

    2012-01-01

    Cassini ISS observed multiple widespread changes in surface brightness in Titan's equatorial regions over the past three years. These brightness variations are attributed to rainfall from cloud systems that appear to form seasonally. Determining the composition of this rainfall is an important step in understanding the "methanological" cycle on Titan. I use data from Cassini VIMS to complete a spectroscopic investigation of multiple rain-wetted areas. I compute "before-and-after" spectral ratios of any areas that show either deposition or evaporation of rain. By comparing these spectral ratios to a model of liquid ethane, I find that the rain is most likely composed of liquid ethane. The spectrum of liquid ethane contains multiple absorption features that fall within the 2-micron and 5-micron spectral windows in Titan's atmosphere. I show that these features are visible in the spectra taken of Titan's surface and that they are characteristically different than those in the spectrum of liquid methane. Furthermore, just as ISS saw the surface brightness reverting to its original state after a period of time, I show that VIMS observations of later flybys show the surface composition in different stages of returning to its initial form.

  6. Seasonal Change on Titan. Chapter 14

    NASA Technical Reports Server (NTRS)

    Lorenz, Ralph D.; Brown, Michael E.; Flasar, F. Michael

    2009-01-01

    Titan displays seasonal changes in the distribution of gas and hazes in its atmosphere, in the character of its methane clouds, and in its temperatures and winds. While Cassini has observed some of these cha rges in detail, some are observable from Earth, and the period of mos t rapid change may be just about to begin in the years after equinox,

  7. Dunes on Titan observed by Cassini Radar

    USGS Publications Warehouse

    Radebaugh, J.; Lorenz, R.D.; Lunine, J.I.; Wall, S.D.; Boubin, G.; Reffet, E.; Kirk, R.L.; Lopes, R.M.; Stofan, E.R.; Soderblom, L.; Allison, M.; Janssen, M.; Paillou, P.; Callahan, P.; Spencer, C.; ,

    2008-01-01

    Thousands of longitudinal dunes have recently been discovered by the Titan Radar Mapper on the surface of Titan. These are found mainly within ??30?? of the equator in optically-, near-infrared-, and radar-dark regions, indicating a strong proportion of organics, and cover well over 5% of Titan's surface. Their longitudinal duneform, interactions with topography, and correlation with other aeolian forms indicate a single, dominant wind direction aligned with the dune axis plus lesser, off-axis or seasonally alternating winds. Global compilations of dune orientations reveal the mean wind direction is dominantly eastwards, with regional and local variations where winds are diverted around topographically high features, such as mountain blocks or broad landforms. Global winds may carry sediments from high latitude regions to equatorial regions, where relatively drier conditions prevail, and the particles are reworked into dunes, perhaps on timescales of thousands to tens of thousands of years. On Titan, adequate sediment supply, sufficient wind, and the absence of sediment carriage and trapping by fluids are the dominant factors in the presence of dunes. ?? 2007 Elsevier Inc. All rights reserved.

  8. Big Impacts and Transient Oceans on Titan

    NASA Astrophysics Data System (ADS)

    Zahnle, K. J.; Korycansky, D. G.; Nixon, C. A.

    2014-02-01

    We ask what happened to Titan after the impacts came. A nominal Menrva heats the surface to ~170 K; it takes heroic assumptions to reach 273 K. Bigger impacts (e.g., putative Hotei impact) produce meltwater oceans that last for decades or centuries.

  9. An update of nitrile photochemistry on Titan

    NASA Technical Reports Server (NTRS)

    Yung, Yuk L.

    1987-01-01

    Comparisons are undertaken between laboratory kinetics experiments and Voyager observations in order to shed light on possible chemical reaction pathways to the generation of cyanogen and dicyanoacetylene in Titan's upper atmosphere. The predicted concentrations of the simple nitrile compounds are found to be of a magnitude realistically corresponding to the Voyager observations.

  10. Titan's inventory of organic surface materials

    USGS Publications Warehouse

    Lorenz, R.D.; Mitchell, K.L.; Kirk, R.L.; Hayes, A.G.; Aharonson, O.; Zebker, H.A.; Paillou, P.; Radebaugh, J.; Lunine, J.I.; Janssen, M.A.; Wall, S.D.; Lopes, R.M.; Stiles, B.; Ostro, S.; Mitri, G.; Stofan, E.R.

    2008-01-01

    Cassini RADAR observations now permit an initial assessment of the inventory of two classes, presumed to be organic, of Titan surface materials: polar lake liquids and equatorial dune sands. Several hundred lakes or seas have been observed, of which dozens are each estimated to contain more hydrocarbon liquid than the entire known oil and gas reserves on Earth. Dark dunes cover some 20% of Titan's surface, and comprise a volume of material several hundred times larger than Earth's coal reserves. Overall, however, the identified surface inventories (>3 ?? 104 km3 of liquid, and >2 ?? 105 km3 of dune sands) are small compared with estimated photochemical production on Titan over the age of the solar system. The sand volume is too large to be accounted for simply by erosion in observed river channels or ejecta from observed impact craters. The lakes are adequate in extent to buffer atmospheric methane against photolysis in the short term, but do not contain enough methane to sustain the atmosphere over geologic time. Unless frequent resupply from the interior buffers this greenhouse gas at exactly the right rate, dramatic climate change on Titan is likely in its past, present and future. Copyright 2008 by the American Geophysical Union.

  11. Titan's inventory of organic surface materials

    NASA Astrophysics Data System (ADS)

    Lorenz, Ralph D.; Mitchell, Karl L.; Kirk, Randolph L.; Hayes, Alexander G.; Aharonson, Oded; Zebker, Howard A.; Paillou, Phillipe; Radebaugh, Jani; Lunine, Jonathan I.; Janssen, Michael A.; Wall, Stephen D.; Lopes, Rosaly M.; Stiles, Bryan; Ostro, Steve; Mitri, Giuseppe; Stofan, Ellen R.

    2008-01-01

    Cassini RADAR observations now permit an initial assessment of the inventory of two classes, presumed to be organic, of Titan surface materials: polar lake liquids and equatorial dune sands. Several hundred lakes or seas have been observed, of which dozens are each estimated to contain more hydrocarbon liquid than the entire known oil and gas reserves on Earth. Dark dunes cover some 20% of Titan's surface, and comprise a volume of material several hundred times larger than Earth's coal reserves. Overall, however, the identified surface inventories (>3 × 104 km3 of liquid, and >2 × 105 km3 of dune sands) are small compared with estimated photochemical production on Titan over the age of the solar system. The sand volume is too large to be accounted for simply by erosion in observed river channels or ejecta from observed impact craters. The lakes are adequate in extent to buffer atmospheric methane against photolysis in the short term, but do not contain enough methane to sustain the atmosphere over geologic time. Unless frequent resupply from the interior buffers this greenhouse gas at exactly the right rate, dramatic climate change on Titan is likely in its past, present and future.

  12. Titan's Impact Craters and Associated Fluvial Features

    NASA Astrophysics Data System (ADS)

    Gilliam, A.; Jurdy, D. M.

    2012-12-01

    The Cassini spacecraft has detected remarkably few impact craters on the surface of Titan. By early 2010, with surface radar coverage reaching 33%, seven certain impact craters were discovered, with another 52 nearly certain and probable ones. The paucity of craters implies that the surface of Titan is very dynamic and relatively young. Dynamical models of the internal structure of Titan suggest the possibility of a subsurface ocean of ammonia-water liquid beneath its icy shell. If a large subsurface ocean does exist, it should have measurable effects on Titan's surface and the morphology of its craters. Using a combination of available Cassini radar-SAR, ISS, and VIMS data, we construct geomorphologic maps of Titan's "certain" impact craters with associated features we interpret as fluvial in origin. The best example, Menrva, a 445 km wide double-ring impact basin, hosts a complex network of channels. On the western, more degraded side of the crater, channels cut through the outer rim. To the east of Menrva, a curious network of channels start near the rim crest and appear to have flowed away into a large catchment basin; the complex is termed Elivagar Flumina. Channels surrounding Menrva display a low order - a classification of stream segments based on the number of tributaries upstream - measuring one or two, occasionally up to three. This matches observations of two other confirmed impact craters with associated fluvial features. A halo of low-order channels encircles Selk, an 80 km diameter crater with a small central peak. Also, Ksa, a 30 km diameter crater with a bright central peak and radial ejecta, has a feature that appears to be a first order channel. These differ radically from the tree-shaped dendritic channels common on Titan, which are generally attributed to heavy rainfall. For example, the Xanadu region, as observed on the T13 swath, exhibits a very complex and dendritic network of channels, where the order of channels reaches six to seven. The

  13. Growth and micro structural studies on Yittria Stabilized Zirconia (YSZ) and Strontium Titanate (STO) buffer layers

    NASA Technical Reports Server (NTRS)

    Srinivas, S.; Pinto, R.; Pai, S. P.; Dsousa, D. P.; Apte, P. R.; Kumar, D.; Purandare, S. C.; Bhatnagar, A. K.

    1995-01-01

    Microstructure of Yittria Stabilized Zirconia (YSZ) and Strontium Titanate (STO) of radio frequency magnetron sputtered buffer layers was studied at various sputtering conditions on Si (100), Sapphire and LaAlO3 (100) substrates. The effect of substrate temperatures up to 800 C and sputtering gas pressures in the range of 50 mTorr. of growth conditions was studied. The buffer layers of YSZ and STO showed a strong tendency for columnar growth was observed above 15 mTorr sputtering gas pressure and at high substrate temperatures. Post annealing of these films in oxygen atmosphere reduced the oxygen deficiency and strain generated during growth of the films. Strong c-axis oriented superconducting YBa2Cu3O7-x (YBCO) thin films were obtained on these buffer layers using pulsed laser ablation technique. YBCO films deposited on multilayers of YSZ and STO were shown to have better superconducting properties.

  14. Human Missions to Europa and Titan - Why Not?

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This report describes a long-term development plan to enable human exploration of the outer solar system, with a focus on Europa and Titan. These are two of the most interesting moons of Jupiter and Saturn, respectively, because they are the places in the solar system with the greatest potential for harboring extraterrestrial life. Since human expeditions to these worlds are considered impossible with current capabilities, the proposal of a well-organized sequence of steps towards making this a reality was formulated. The proposed Development Plan, entitled Theseus, is the outcome of a recent multinational study by a group of students in the framework of the Master of Space Studies (MSS) 2004 course at the International Space University (ISU). The Theseus Program includes the necessary development strategies in key scientific and technological areas that are essential for identifying the requirements for the exploration of the outer planetary moons. Some of the topics that are analysed throughout the plan include: scientific observations at Europa and Titan, advanced propulsion and nuclear power systems, in-situ resource utilization, radiation mitigation techniques, closed life support systems, habitation for long-term spaceflight, and artificial gravity. In addition to the scientific and technological aspects of the Theseus Program, it was recognized that before any research and development work may begin, some level of program management must be established. Within this chapter, legal issues, national and international policy, motivation, organization and management, economic considerations, outreach, education, ethics, and social implications are all considered with respect to four possible future scenarios which enable human missions to the outer solar system. The final chapter of the report builds upon the foundations set by Theseus through a case study. This study illustrates how such accomplishments could influence a mission to Europa to search for evidence

  15. Ion acceleration enhanced by target ablation

    SciTech Connect

    Zhao, S.; Lin, C. Wang, H. Y.; Lu, H. Y.; He, X. T.; Yan, X. Q.; Chen, J. E.; Cowan, T. E.

    2015-07-15

    Laser proton acceleration can be enhanced by using target ablation, due to the energetic electrons generated in the ablation preplasma. When the ablation pulse matches main pulse, the enhancement gets optimized because the electrons' energy density is highest. A scaling law between the ablation pulse and main pulse is confirmed by the simulation, showing that for given CPA pulse and target, proton energy improvement can be achieved several times by adjusting the target ablation.

  16. Two-Dimensional Finite Element Ablative Thermal Response Analysis of an Arcjet Stagnation Test

    NASA Technical Reports Server (NTRS)

    Dec, John A.; Laub, Bernard; Braun, Robert D.

    2011-01-01

    The finite element ablation and thermal response (FEAtR, hence forth called FEAR) design and analysis program simulates the one, two, or three-dimensional ablation, internal heat conduction, thermal decomposition, and pyrolysis gas flow of thermal protection system materials. As part of a code validation study, two-dimensional axisymmetric results from FEAR are compared to thermal response data obtained from an arc-jet stagnation test in this paper. The results from FEAR are also compared to the two-dimensional axisymmetric computations from the two-dimensional implicit thermal response and ablation program under the same arcjet conditions. The ablating material being used in this arcjet test is phenolic impregnated carbon ablator with an LI-2200 insulator as backup material. The test is performed at the NASA, Ames Research Center Interaction Heating Facility. Spatially distributed computational fluid dynamics solutions for the flow field around the test article are used for the surface boundary conditions.

  17. Cassini/Huygens Investigations of Titan's Methane Cycle

    NASA Astrophysics Data System (ADS)

    Griffith, C. A.; Penteado, P.

    2008-12-01

    In Titan's atmosphere, the second most abundant constituent, methane, exists as a gas, liquid and solid, and cycles between the atmosphere and surface. Similar to Earth's hydrological cycle, Titan sports clouds, rain, and lakes. Yet, Titan's cycle differs dramatically from its terrestrial counterpart, and reveals the workings of weather in an atmosphere that is ten times thicker than Earth's atmosphere, that is two orders of magnitude less illuminated, and that involves a different condensable. Measurements of Titan's troposphere, where the methane cycle plays out, are limited largely to spectral images of Titan's clouds, several temperature profiles by Voyager, Huygens and Cassini, recent Keck spectra of the surface methane humidity, and one vertical profile of Titan's methane abundance, measured on a summer afternoon in Titan's tropical atmosphere by the Huygens probe. The salient features of Titan's methane cycle are distinctly alien: clouds have predominated the northern and southern polar atmospheres; the one humidity profile precisely matches the profile (of cartoonish simplicity) used in pre-Cassini models, and surface features correlate with latitude. Data of Titan's troposphere are analyzed with thermodynamic and radiative transfer calculations, and synthesized with other studies of Titan's stratosphere and surface, to investigate the workings of Titan's methane cycle. At the end of Cassini's nominal mission, we find that Titan's weather, climate and surface-to-atmosphere exchange of volatiles vastly differs from the manifestation of these processes on Earth, largely as a result of different basic characteristics of these planetary bodies. The talk ends with a comparison between Titan and Earth's tropospheres, their fundamental properties, the energetics of their condensible cycles, their weather and climates. References: Griffith C.A. et al. Titan's Tropical Storms in an Evolving Atmosphere. Ap.J. In Press (2008). Griffith C.A. Storms, Polar Deposits, and

  18. Titan: a laboratory for prebiological organic chemistry

    NASA Technical Reports Server (NTRS)

    Sagan, C.; Thompson, W. R.; Khare, B. N.

    1992-01-01

    When we examine the atmospheres of the Jovian planets (Jupiter, Saturn, Uranus, and Neptune), the satellites in the outer solar system, comets, and even--through microwave and infrared spectroscopy--the cold dilute gas and grains between the stars, we find a rich organic chemistry, presumably abiological, not only in most of the solar system but throughout the Milky Way galaxy. In part because the composition and surface pressure of the Earth's atmosphere 4 x 10(9) years ago are unknown, laboratory experiments on prebiological organic chemistry are at best suggestive; but we can test our understanding by looking more closely at the observed extraterrestrial organic chemistry. The present Account is restricted to atmospheric organic chemistry, primarily on the large moon of Saturn. Titan is a test of our understanding of the organic chemistry of planetary atmospheres. Its atmospheric bulk composition (N2/CH4) is intermediate between the highly reducing (H2/He/CH4/NH3/H2O) atmospheres of the Jovian planets and the more oxidized (N2/CO2/H2O) atmospheres of the terrestrial planets Mars and Venus. It has long been recognized that Titan's organic chemistry may have some relevance to the events that led to the origin of life on Earth. But with Titan surface temperatures approximately equal to 94 K and pressures approximately equal to 1.6 bar, the oceans of the early Earth have no ready analogue on Titan. Nevertheless, tectonic events in the water ice-rich interior or impact melting and slow re-freezing may lead to an episodic availability of liquid water. Indeed, the latter process is the equivalent of a approximately 10(3)-year-duration shallow aqueous sea over the entire surface of Titan.

  19. Low-Latitude Ethane Rain on Titan

    NASA Astrophysics Data System (ADS)

    Dalba, Paul; Buratti, B. J.; Brown, R. H.; Barnes, J. W.; Baines, K. H.; Sotin, C.; Clark, R. N.; Lawrence, K. J.; Nicholson, P. D.

    2012-10-01

    Cassini ISS observed multiple widespread changes in surface brightness in Titan's equatorial regions over the past three years (Barnes, J. W. et al. 2012, Icarus, submitted). These brightness variations are attributed to rainfall from cloud systems that appear to form seasonally (Turtle, E. P. et al. 2011, Science, 331, 1414-1417). Determining the composition of this rainfall is an important step in understanding the “methanological” cycle that dominates Titan's surface and atmosphere. In this study, we use data from Cassini VIMS to complete a thorough spectroscopic investigation of rain-wetted areas near Yalaing Terra, Hetpet Regio and central Adiri on Titan. We compute “before-and-after” spectral ratios of any areas that show either deposition or evaporation of rain at any point in the time span of August 2009 to January 2012. By comparing these spectral ratios to a model of liquid ethane that was calculated to match the resolution and sampling interval of VIMS (Brown, R. H. et al. 2008, Nature, 454, 607-610), we find that the rain is most likely composed of liquid ethane. The spectrum of liquid ethane contains multiple absorption features that fortunately fall within the 2-micron and 5-micron spectral windows in Titan's atmosphere. We show that these features are visible in the spectra taken of Titan's surface and that they are characteristically different than those in the spectrum of liquid methane. Furthermore, just as ISS saw the surface brightness reverting to its original state after a period of time, we show that VIMS observations of later flybys show the surface composition in different stages of returning to its initial form as well. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology under contract to the National Aeronautics and Space Administration. Copyright 2012. All rights reserved.

  20. Low-latitude ethane rain on Titan

    NASA Astrophysics Data System (ADS)

    Dalba, P. A.; Buratti, B. J.; Brown, R. H.; Barnes, J. W.; Baines, K. H.; Sotin, C.; Clark, R. N.; Lawrence, K. J.; Nicholson, P. D.

    2012-12-01

    Cassini ISS observed multiple widespread changes in surface brightness in Titan's equatorial regions over the past three years (Barnes, J. W. et al. 2012, Icarus, submitted). These brightness variations are attributed to rainfall from cloud systems that appear to form seasonally (Turtle, E. P. et al. 2011, Science, 331, 1414-1417). Determining the composition of this rainfall is an important step in understanding the "methanological" cycle that dominates Titan's surface and atmosphere. In this study, we use data from Cassini VIMS to complete a thorough spectroscopic investigation of rain-wetted areas near Yalaing Terra, Hetpet Regio and central Adiri on Titan. We compute "before-and-after" spectral ratios of any areas that show either deposition or evaporation of rain at any point in the time span of August 2009 to January 2012. By comparing these spectral ratios to a model of liquid ethane that was calculated to match the resolution and sampling interval of VIMS (Brown, R. H. et al. 2008, Nature, 454, 607-610), we find that the rain is most likely composed of liquid ethane. The spectrum of liquid ethane contains multiple absorption features that fortunately fall within the 2-micron and 5-micron spectral windows in Titan's atmosphere. We show that these features are visible in the spectra taken of Titan's surface and that they are characteristically different than those in the spectrum of liquid methane. Furthermore, just as ISS saw the surface brightness reverting to its original state after a period of time, we show that VIMS observations of later flybys show the surface composition in different stages of returning to its initial form as well. Funded by NASA.

  1. Aerocapture Technology Developments from NASA's In-Space Propulsion Technology Program

    NASA Technical Reports Server (NTRS)

    Munk, Michelle M.; Moon, Steven A.

    2007-01-01

    This paper will explain the investment strategy, the role of detailed systems analysis, and the hardware and modeling developments that have resulted from the past 5 years of work under NASA's In-Space Propulsion Program (ISPT) Aerocapture investment area. The organizations that have been funded by ISPT over that time period received awards from a 2002 NASA Research Announcement. They are: Lockheed Martin Space Systems, Applied Research Associates, Inc., Ball Aerospace, NASA's Ames Research Center, and NASA's Langley Research Center. Their accomplishments include improved understanding of entry aerothermal environments, particularly at Titan, demonstration of aerocapture guidance algorithm robustness at multiple bodies, manufacture and test of a 2-meter Carbon-Carbon "hot structure," development and test of evolutionary, high-temperature structural systems with efficient ablative materials, and development of aerothermal sensors that will fly on the Mars Science Laboratory in 2009. Due in large part to this sustained ISPT support for Aerocapture, the technology is ready to be validated in flight.

  2. Laser ablation studies in southern Africa

    NASA Astrophysics Data System (ADS)

    McKenzie, Edric; Forbes, A.; Turner, G. R.; Michaelis, Max M.

    2000-08-01

    With the launch of the South African National Laser Centre, new programs will need to be defined. Medical, environmental and industrial laser applications must obviously take top priority -- as opposed to the uranium isotope separation and military applications of the past. We argue however, that a small effort in laser ablation for space propulsion is justifiable, since a few very large CO2 lasers are available and since two tentative propulsion experiments have already been conducted in South Africa. We attempt to give LISP (Laser Impulse Space Propulsion) an equatorial and a Southern dimension.

  3. Coupling of oxygen, nitrogen, and hydrocarbon species in the photochemistry of Titan's atmosphere

    NASA Astrophysics Data System (ADS)

    Dobrijevic, M.; Hébrard, E.; Loison, J. C.; Hickson, K. M.

    2014-01-01

    Analysis of recent detections of water by Herschel/HIFI-PACS and Cassini/CIRS suggest for a steep gradient of the water profile in the lower stratosphere of Titan's atmosphere (Cottini, V., Nixon, C.A., Jennings, D.E., Anderson, C.M., Gorius, N., Bjoraker, G.L., Coustenis, A., Teanby, N.A., Achterberg, R.K., Béezard, B., de Kok, R., Lellouch, E., Irwin, P.G.J., Flasar, F.M., Bampasidis, G. [2012]. Icarus 220, 855-862; Moreno, R., Lellouch, E., Lara, L.M., Feuchtgruber, H., Rengel, M., Hartogh, P., Courtin, R. [2012]. Icarus 221, 753-767). This result provides a good opportunity to better understand the origin of oxygen compounds. However, the current photochemical models use an incomplete oxygen chemical scheme. In the present work, we improve the photochemistry of oxygen and introduce in particular a coupling between hydrocarbon, oxygen and nitrogen chemistries. Through the use of several different scenarios, we show that some oxygen compound abundances are sensitive to the nature of oxygen atoms (O+, OH and H2O) and the source of the flux (micrometeorites ablation or Enceladus' plume activity). Our model also predicts the presence of new and as yet undetected compounds such as NO (nitric oxide), HNO (nitrosyl hydride), HNCO (isocyanic acid) and N2O (nitrous oxide). Their future putative detection will give valuable constraints to discriminate between the different hypotheses for the nature and the source of oxygen compounds in the atmosphere of Titan. Through the use of a Monte Carlo-based uncertainty propagation study and global sensitivity analysis, we identify the key reactions that should be studied in priority to improve coupled photochemical models of Titan's atmosphere.

  4. Visualization of Capsule Reentry Vehicle Heat Shield Ablation using Naphthalene Planar Laser-Induced Fluorescence Imaging

    NASA Astrophysics Data System (ADS)

    Combs, Christopher; Clemens, Noel; Danehy, Paul

    2012-11-01

    NASA has continued interest in the study of ablation owing to the need to develop suitable thermal protection systems for spacecraft that undergo planetary entry. Ablation is a complex multi-physics process, and codes that predict it require a number of coupled submodels, each of which requires validation. For example, Reynolds-averaged Navier Stokes (RANS) and large-eddy simulation (LES) codes require models of the turbulent transport of ablation products under variable compressibility and pressure gradient conditions. A new technique has been developed at The University of Texas at Austin that uses planar laser-induced fluorescence (PLIF) of a low-temperature sublimating ablator (naphthalene) to enable visualization of the ablation products as they are transported in a boundary layer. While high temperature ablation is extremely difficult to recreate in a laboratory environment, low temperature ablation creates a limited physics problem that can be used to simulate the ablation process. In the current work a subscale capsule reentry vehicle model with a solid naphthalene heat shield is tested in a Mach 5 wind tunnel. PLIF imaging reveals the distribution of the ablation products as they are transported into the boundary layer and over the capsule shoulders. Work supported by NASA Space Technology Research Fellowship Program under grant NNX11AN55H.

  5. Development of Naphthalene PLIF for Making Quantitative Measurements of Ablation Products Transport in Supersonic Flows

    NASA Astrophysics Data System (ADS)

    Combs, Christopher; Clemens, Noel

    2014-11-01

    Ablation is a multi-physics process involving heat and mass transfer and codes aiming to predict ablation are in need of experimental data pertaining to the turbulent transport of ablation products for validation. Low-temperature sublimating ablators such as naphthalene can be used to create a limited physics problem and simulate ablation at relatively low temperature conditions. At The University of Texas at Austin, a technique is being developed that uses planar laser-induced fluorescence (PLIF) of naphthalene to visualize the transport of ablation products in a supersonic flow. In the current work, naphthalene PLIF will be used to make quantitative measurements of the concentration of ablation products in a Mach 5 turbulent boundary layer. For this technique to be used for quantitative research in supersonic wind tunnel facilities, the fluorescence properties of naphthalene must first be investigated over a wide range of state conditions and excitation wavelengths. The resulting calibration of naphthalene fluorescence will be applied to the PLIF images of ablation from a boundary layer plug, yielding 2-D fields of naphthalene mole fraction. These images may help provide data necessary to validate computational models of ablative thermal protection systems for reentry vehicles. Work supported by NASA Space Technology Research Fellowship Program under grant NNX11AN55H.

  6. Ablative Approaches for Pulmonary Metastases.

    PubMed

    Boyer, Matthew J; Ricardi, Umberto; Ball, David; Salama, Joseph K

    2016-02-01

    Pulmonary metastases are common in patients with cancer for which surgery is considered a standard approach in appropriately selected patients. A number of patients are not candidates for surgery due to a medical comorbidities or the extent of surgery required. For these patients, noninvasive or minimally invasive approaches to ablate pulmonary metastases are potential treatment strategies. This article summarizes the rationale and outcomes for non-surgical treatment approaches, including radiotherapy, radiofrequency and microwave ablation, for pulmonary metastases.

  7. Laser ablation in analytical chemistry.

    PubMed

    Russo, Richard E; Mao, Xianglei; Gonzalez, Jhanis J; Zorba, Vassilia; Yoo, Jong

    2013-07-01

    In 2002, we wrote an Analytical Chemistry feature article describing the Physics of Laser Ablation in Microchemical Analysis. In line with the theme of the 2002 article, this manuscript discusses current issues in fundamental research, applications based on detecting photons at the ablation site (LIBS and LAMIS) and by collecting particles for excitation in a secondary source (ICP), and directions for the technology. PMID:23614661

  8. Bone and Soft Tissue Ablation

    PubMed Central

    Foster, Ryan C.B.; Stavas, Joseph M.

    2014-01-01

    Bone and soft tissue tumor ablation has reached widespread acceptance in the locoregional treatment of various benign and malignant musculoskeletal (MSK) lesions. Many principles of ablation learned elsewhere in the body are easily adapted to the MSK system, particularly the various technical aspects of probe/antenna design, tumoricidal effects, selection of image guidance, and methods to reduce complications. Despite the common use of thermal and chemical ablation procedures in bone and soft tissues, there are few large clinical series that show longitudinal benefit and cost-effectiveness compared with conventional methods, namely, surgery, external beam radiation, and chemotherapy. Percutaneous radiofrequency ablation of osteoid osteomas has been evaluated the most and is considered a first-line treatment choice for many lesions. Palliation of painful metastatic bone disease with thermal ablation is considered safe and has been shown to reduce pain and analgesic use while improving quality of life for cancer patients. Procedure-related complications are rare and are typically easily managed. Similar to all interventional procedures, bone and soft tissue lesions require an integrated approach to disease management to determine the optimum type of and timing for ablation techniques within the context of the patient care plan. PMID:25053865

  9. A green synthesis of a layered titanate, potassium lithium titanate; lower temperature solid-state reaction and improved materials performance

    SciTech Connect

    Ogawa, Makoto; Morita, Masashi; Igarashi, Shota; Sato, Soh

    2013-10-15

    A layered titanate, potassium lithium titanate, with the size range from 0.1 to 30 µm was prepared to show the effects of the particle size on the materials performance. The potassium lithium titanate was prepared by solid-state reaction as reported previously, where the reaction temperature was varied. The reported temperature for the titanate preparation was higher than 800 °C, though 600 °C is good enough to obtain single-phase potassium lithium titanate. The lower temperature synthesis is cost effective and the product exhibit better performance as photocatalysts due to surface reactivity. - Graphical abstract: Finite particle of a layered titanate, potassium lithium titanate, was prepared by solid-state reaction at lower temperature to show modified materials performance. Display Omitted - Highlights: • Potassium lithium titanate was prepared by solid-state reaction. • Lower temperature reaction resulted in smaller sized particles of titanate. • 600 °C was good enough to obtain single phased potassium lithium titanate. • The product exhibited better performance as photocatalyst.

  10. The TITAN Reversed-Field Pinch fusion reactor study: Scoping phase report

    SciTech Connect

    Not Available

    1987-01-01

    The TITAN research program is a multi-institutional effort to determine the potential of the Reversed-Field Pinch (RFP) magnetic fusion concept as a compact, high-power-density, and ''attractive'' fusion energy system from economic (cost of electricity, COE), environmental, and operational viewpoints. In particular, a high neutron wall loading design (18 MW/m/sup 2/) has been chosen as the reference case in order to quantify the issue of engineering practicality, to determine the physics requirements and plasma operating mode, to assess significant benefits of compact systems, and to illuminate the main drawbacks. The program has been divided into two phases, each roughly one year in length: the Scoping Phase and the Design Phase. During the scoping phase, the TITAN design team has defined the parameter space for a high mass power density (MPD) RFP reactor, and explored a variety of approaches to the design of major subsystems. Two major design approaches consistent with high MPD and low COE, the lithium-vanadium blanket design and aqueous loop-in-pool design, have been selected for more detailed engineering evaluation in the design phase. The program has retained a balance in its approach to investigating high MPD systems. On the one hand, parametric investigations of both subsystems and overall system performance are carried out. On the other hand, more detailed analysis and engineering design and integration are performed, appropriate to determining the technical feasibility of the high MPD approach to RFP fusion reactors. This report describes the work of the scoping phase activities of the TITAN program. A synopsis of the principal technical findings and a brief description of the TITAN multiple-design approach is given. The individual chapters on Plasma Physics and Engineering, Parameter Systems Studies, Divertor, Reactor Engineering, and Fusion Power Core Engineering have been cataloged separately.

  11. Conformal Ablative Thermal Protection System for Planetary and Human Exploration Missions: Overview of the Technology Maturation Efforts Funded by NASA's Game Changing Development Program

    NASA Technical Reports Server (NTRS)

    Beck, Robin A.; Arnold, James O.; Gasch, Matthew J.; Stackpoole, Margaret M.; Fan, Wendy; Szalai, Christine E.; Wercinski, Paul F.; Venkatapathy, Ethiraj

    2012-01-01

    The Office of Chief Technologist (OCT), NASA has identified the need for research and technology development in part from NASA's Strategic Goal 3.3 of the NASA Strategic Plan to develop and demonstrate the critical technologies that will make NASA's exploration, science, and discovery missions more affordable and more capable. Furthermore, the Game Changing Development Program (GCDP) is a primary avenue to achieve the Agency's 2011 strategic goal to "Create the innovative new space technologies for our exploration, science, and economic future." In addition, recently released "NASA space Technology Roadmaps and Priorities," by the National Research Council (NRC) of the National Academy of Sciences stresses the need for NASA to invest in the very near term in specific EDL technologies. The report points out the following challenges (Page 2-38 of the pre-publication copy released on February 1, 2012): Mass to Surface: Develop the ability to deliver more payload to the destination. NASA's future missions will require ever-greater mass delivery capability in order to place scientifically significant instrument packages on distant bodies of interest, to facilitate sample returns from bodies of interest, and to enable human exploration of planets such as Mars. As the maximum mass that can be delivered to an entry interface is fixed for a given launch system and trajectory design, the mass delivered to the surface will require reduction in spacecraft structural mass; more efficient, lighter thermal protection systems; more efficient lighter propulsion systems; and lighter, more efficient deceleration systems. Surface Access: Increase the ability to land at a variety of planetary locales and at a variety of times. Access to specific sites can be achieved via landing at a specific location (s) or transit from a single designated landing location, but it is currently infeasible to transit long distances and through extremely rugged terrain, requiring landing close to the

  12. Exploration of Titan by Balloon or Airship

    NASA Astrophysics Data System (ADS)

    Lorenz, R. D.

    2005-12-01

    Titan's surface is recognized as a focus for future exploration, yet Cassini shows it to be incredibly diverse - landers or even rovers to a handful of sites will not capture the range of phenomena and materials in this exotic landscape. Thus a platform able to access many widely-spaced locations on Titan is essential. Fortunately, Titan's low gravity and thick atmosphere lends itself to exploration by airborne vehicles such as balloons, airplanes, helicopters and airships. The latter vehicle type has received particular attention, since it combines `go to' ability to traverse to and stationkeep at targets of interest, while being, unlike heavier-than-air vehicles, `fail-safe' in terms of floating passively in an unpowered condition. In-situ analysis of surface chemistry can be performed using a tethered sampler. An airship or similar mission at Titan could be augmented by an orbiter, by remote sensing for mission planning and scientific context, by acting as a navigation beacon, and as a communications relay. However, none of these are essential. First, Cassini data allows the identification of target regions of interest at a level of a few kilometers - enough to know where the airship should explore further. Second, clear infrared windows in Titan's atmosphere permit the use of the Sun, Saturn and other targets as beacons for autonomous optical navigation at a large scale : optical odometry, correlation of landscape features with Cassini data, and the impressive Very Long Baseline Interferometry demonstrated by radio astronomers supporting Huygens may permit kilometer-scale location. Finally, while orbiter relay can increase the number of communication opportunities (depending on latitude) and the total data return, tens of megabits per day can be returned with direct-to-Earth communication. A portfolio of mission options therefore exists with a tradeoff of capability versus cost, from a passive balloon with direct-to-Earth only, to an airship with surface

  13. Tidal effects of disconnected hydrocarbon seas on Titan.

    PubMed

    Dermott, S F; Sagan, C

    1995-03-16

    Thermodynamic and photochemical arguments suggest that Titan, the largest satellite of Saturn, has a deep ocean of liquid hydrocarbons. At visible wavelengths, Titan's surface is obscured by a thick stratospheric haze, but radar observations have revealed large regions of high surface reflectivity that are inconsistent with a global hydrocarbon ocean. Titan's surface has also been imaged at infrared wavelengths, and the highest-resolution data (obtained by the Hubble Space Telescope) show clear variations in surface albedo and/or topography. The natural interpretation of these observations is that Titan, like the Earth, has continents and oceans. But Titan's high orbital eccentricity poses a problem for this interpretation, as the effects of oceanic tidal friction would have circularized Titan's orbit for most configurations of oceans and continents. Here we argue that a more realistic topography, in which liquid hydrocarbons are confined to a number of disconnected seas or crater lakes, may satisfy both the dynamical and observational constraints. PMID:7885443

  14. Potential chemical evolution of aerosols on Titan's surface: some new results on Titan's tholins

    NASA Astrophysics Data System (ADS)

    Coll, P.; Poch, O.; Ramirez, S. I.; Buch, A.; Brassé, C.; Raulin, F.

    2011-10-01

    Titan's environment hosts a complex organic chemistry that can be investigated from Earth-based laboratory experiments. One of the key astrobiological questions of Titan's environment is the fate of the organic aerosols produced in the atmosphere, after they are deposited on the surface. In the present study, we report the geological structures these aerosols may encounter in the light of the last observations of the Cassini-Huygens mission. We chose to quantify the production of some astrobiologically interesting molecules in putative ammonia-water bodies likely to be present at the surface or subsurface of Titan, as crater melt pools or cryolavas. After aerosol analogues (tholins) synthesis and surface hydrolysis simulation, some resulting products were identified and quantified. Tholins were found to be very reactive toward an oxygen source. Urea was identified as the main product of Titan's tholins hydrolysis in ammonia-water solutions, with a production yield in mass, ranging from 6 to 12% at 279 K after 10 weeks. Several amino acids - alanine, glycine and aspartic acid - and perhaps the uracil nucleobase were also produced with yields from 0.001 to 0.4%. The determination of production yields carried out by the present study is a major step into the characterization of potential aerosols evolution on Titan.

  15. Mapping of Titan: First Results from the Cassini RADAR

    NASA Technical Reports Server (NTRS)

    Stofan, E. R.; Elachi, C.; Lopes, R.; Lorenz, R.; Kirk, R. L.; Paganelli, F.; Wood, C. A.; Wall, S. D.; Luine, J.; Soderblom, L. A.

    2005-01-01

    Like Venus, the surface of Titan is hidden from view, with little known about its geology prior to Cassini. The first Synthetic Aperture Radar (SAR) swath across the surface of Titan has revealed a surprisingly complex surface, with few features that can be reliably identified as impact craters. More detailed reports on the results of the first radar encounter with Titan can be found in this volume.

  16. Titan's rotation reveals an internal ocean and changing zonal winds

    USGS Publications Warehouse

    Lorenz, R.D.; Stiles, B.W.; Kirk, R.L.; Allison, M.D.; Del Marmo, P.P.; Iess, L.; Lunine, J.I.; Ostro, S.J.; Hensley, S.

    2008-01-01

    Cassini radar observations of Saturn's moon Titan over several years show that its rotational period is changing and is different from its orbital period. The present-day rotation period difference from synchronous spin leads to a shift of ???0.36?? per year in apparent longitude and is consistent with seasonal exchange of angular momentum between the surface and Titan's dense superrotating atmosphere, but only if Titan's crust is decoupled from the core by an internal water ocean like that on Europa.

  17. Detection of the Kuiper bands in the spectrum of Titan

    NASA Technical Reports Server (NTRS)

    Danehy, R. G.; Owen, T.; Lutz, B. L.; Woodman, J. H.

    1978-01-01

    New spectra of Titan centered at 7500 A, at resolutions of 4 and 1 A are presented. Weak absorptions coincident with features observed in the spectra of Uranus and Neptune are found. This observation suggests methane abundances in excess of 1 km-am, thereby, emphasizing the complexity of line formation in Titan's atmosphere. The question of the total atmospheric pressure of Titan must be reexamined.

  18. Performance of Conformable Phenolic Impregnated Carbon Ablator in Aerothermal Environments

    NASA Technical Reports Server (NTRS)

    Thornton, Jeremy; Fan, Wendy; Stackpoole, Mairead; Kao, David; Skokova, Kristina; Chavez-Garcia, Jose

    2012-01-01

    Conformable Phenolic Impregnated Carbon Ablator, a cousin of Phenolic Impregnated Carbon Ablator (PICA), was developed at NASA Ames Research Center as a lightweight thermal protection system under the Fundamental Aeronautics Program. PICA is made using a brittle carbon substrate, which has a very low strain to failure. Conformable PICA is made using a flexible carbon substrate, a felt in this case. The flexible felt significantly increases the strain to failure of the ablator. PICA is limited by its thermal mechanical properties. Future NASA missions will require heatshields that are more fracture resistant than PICA and, as a result, NASA Ames is working to improve PICA's performance by developing conformable PICA to meet these needs. Research efforts include tailoring the chemistry of conformable PICA with varying amounts of additives to enhance mechanical properties and testing them in aerothermal environments. This poster shows the performance of conformable PICA variants in arc jets tests. Some mechanical and thermal properties will also be presented.

  19. Coupled atmosphere-ocean models of Titan's past

    NASA Technical Reports Server (NTRS)

    Mckay, Christopher P.; Pollack, James B.; Lunine, Jonathan I.; Courtin, Regis

    1993-01-01

    The behavior and possible past evolution of fully coupled atmosphere and ocean model of Titan are investigated. It is found that Titan's surface temperature was about 20 K cooler at 4 Gyr ago and will be about 5 K warmer 0.5 Gyr in the future. The change in solar luminosity and the conversion of oceanic CH4 to C2H6 drive the evolution of the ocean and atmosphere over time. Titan appears to have experienced a frozen epoch about 3 Gyr ago independent of whether an ocean is present or not. This finding may have important implications for understanding the inventory of Titan's volatile compounds.

  20. Planetary radio astronomy observations during the Voyager 1 Titan flyby

    NASA Technical Reports Server (NTRS)

    Daigne, G.; Pedersen, B. M.; Kaiser, M. L.; Desch, M. D.

    1982-01-01

    During the Voyager 1 Titan flyby, unusual radio emissions were observed by the planetary radio astronomy experiment in the 20- to 97-kHz frequency range. It is shown that Titan itself is not the source of the observed radio emission. The emission features are attributed to modification of the normal Saturn kilometric radiation by propagation effects in enhanced density structures within the Titan wake. Furthermore, spiky emissions observed in the magnetic wake of Titan are interpreted in terms of local electrostatic instabilities at the electron plasma frequency. From these measurements a range of electron densities in the wake region is derived, and the consistency of the results is discussed.

  1. Titanate-based adsorbents for radioactive ions entrapment from water.

    PubMed

    Yang, Dongjiang; Liu, Hongwei; Zheng, Zhanfeng; Sarina, Sarina; Zhu, Huaiyong

    2013-03-21

    This feature article reviews some titanate-based adsorbents for the removal of radioactive wastes (cations and anions) from water. At the beginning, we discuss the development of the conventional ion-exchangeable titanate powders for the entrapment of radioactive cations, such as crystalline silicotitanate (CST), monosodium titanate (MST), peroxotitanate (PT). Then, we specially emphasize the recent progress in the uptake of radioactive ions by one-dimensional (1D) sodium titanate nanofibers and nanotubes, which includes the synthesis and phase transformation of the 1D nanomaterials, adsorption ability (capacity, selectivity, kinetics, etc.) of radioactive cations and anions, and the structural evolution during the adsorption process.

  2. Aerosol properties in Titan's upper atmosphere

    NASA Astrophysics Data System (ADS)

    Lavvas, Panayotis; Koskinen, Tommi; Royer, Emilie; Rannou, Pascal; West, Robert

    2016-06-01

    Multiple Cassini observations reveal that the abundant aerosol particles in Titan's atmosphere are formed at high altitudes, particularly in the thermosphere. They subsequently fall towards the lower atmosphere and in their path their size, shape, and population change in reflection to the variable atmospheric condition. Although multiple observations can help us retrieve information for the aerosol properties in the lower atmosphere, we have limited information for the aerosol properties between their formation region in the thermosphere and the upper region of the main haze layer or the detached aerosol layer. Observations at UV wavelengths are the only way to probe this part of the atmosphere and help us retrieve the aerosol properties. The presentation will provide an overview of the available observations, and discuss their implications for the production and evolution of Titan's aerosols.

  3. The thermal structure of Titan's atmosphere

    NASA Astrophysics Data System (ADS)

    McKay, C. P.; Pollack, J. B.; Courtin, R.

    1989-07-01

    The present radiative-convective model of the Titan atmosphere thermal structure obtains the solar and IR radiation in a series of spectral intervals with vertical resolution. Haze properties have been determined with a microphysics model encompassing a minimum of free parameters. It is determined that gas and haze opacity alone, using temperatures established by Voyager observations, yields a model that is within a few percent of the radiative convective balance throughout the Titan atmosphere. Model calculations of the surface temperature are generally colder than the observed value by 5-10 K; better agreement is obtained through adjustment of the model parameters. Sunlight absorption by stratospheric haze and pressure-induced gas opacity in the IR are the most important thermal structure-controlling factors.

  4. Buoyant station mission comcepts for titan exploration

    NASA Astrophysics Data System (ADS)

    Friedlander, A. L.

    1985-10-01

    An advanced mission to this unique satellite of Saturn appropriate to the turn-of-the-century time period is described. The mission concept evolves about one or more buoyant stations (balloons and/or airship) operating at varying altitudes in Titan's atmosphere. An orbiter of Titan provides communications link support and accomplishes remote sensing science objectives. Use of buoyant stations are favored over a fixed site lander for two reasons: (1) adaptable to several possible surface physical states and topographies; and (2) capable of exploring both the atmosphere and surface with regional and possibly global mobility. Auxiliary payload concepts investigated include tethered packages and sounding rockets deployed from the buoyant station, and haze probes and surface penetrators deployed from the orbiter. The paper describes science objectives and payloads, propulsion system/mass delivery trades, balloon design requirements and deployment/motion characteristics, and communications link geometry and data characteristics.

  5. Evidence for frozen hydrocarbons on Titan

    NASA Astrophysics Data System (ADS)

    Soderblom, Jason M.; Barnes, Jason W.; Brown, Robert H.; Chevrier, Vincent; Farnsworth, Kendra; Soderblom, Laurence A.

    2016-10-01

    Cassini Visual and Infrared Mapping Spectrometer (VIMS) and Imaging Science Subsystem (ISS) have twice, now, observed widespread darkening of Titan's surface that has been interpreted as evidence of rainfall (Turtle et al., 2009, GRL 36; Turtle et al., 2011, Science 331) followed by an increase in albedo, well beyond the pre-darkened albedo (Barnes et al., 2013, Planet. Sci. 2; Soderblom et al., 2014, DPS). Based on the timescale and magnitude of the albedo changes, and the correlations between the timescale and temperature (inferred from latitude), we favor a thermodynamically controlled process to explain the brightening. Herein, we present a detailed comparison of the IR spectra of the bright materials of these two events. We also discuss the implications on the interpretation of these data from recent laboratory work investigating the freezing of ethane at Titan-like conditions (Farnsworth et al., 2016, LPSC 47).

  6. Observations of Titan IIIC Transtage Fragmentation Debris

    NASA Astrophysics Data System (ADS)

    Cowardin, H.; Buckalew, B.; Barker, E.; Abercromby, K.; Seitzer, P.; Cardona, T.; Krisko, P.; Lederer, S.

    2013-09-01

    The fragmentation of a Titan IIIC Transtage (1968-081) on 21 February 1992 is one of only two known break-ups in or near geosynchronous orbit. The original rocket body and 24 pieces of debris are currently being tracked by the U. S. Space Surveillance Network (SSN). The rocket body (SSN# 3432) and several of the original fragments (SSN# 25000, 25001, 30000, and 33511) were observed in survey mode during 2004-2010 using the 0.6 m Michigan Orbital DEbris Survey Telescope (MODEST) in Chile using a broad R filter. This paper presents a size distribution for all calibrated magnitude data acquired on MODEST. Size distribution plots are also shown using historical models for small fragmentation debris (down to 10 cm) thought to be associated with the Titan Transtage break-up. In November 2010, visible broadband photometry (Johnson/Kron-Cousins BVRI) was acquired with the 0.9 m Small and Moderate Aperture Research Telescope System (SMARTS) at the Cerro Tololo Inter-American Observatory (CTIO) in Chile on several Titan fragments (SSN 25001, 33509, and 33510) and the parent rocket body (SSN 3432). Color index data are used to determine the fragment brightness distribution and how the data compares to spacecraft materials measured in the laboratory using similar photometric measurement techniques. In order to better characterize the break-up fragments, spectral measurements were acquired on three Titan fragments (one fragment observed over two different time periods) using the 6.5-m Magellan telescopes at Las Campanas Observatory in Chile. The telescopic spectra of SSN 25000 (May 2012 and January 2013), SSN 38690, and SSN 38699 are compared with laboratory acquired spectra of materials (e.g., aluminum and various paints) to determine the surface material.

  7. Encouragement from Jupiter for Europe's Titan Probe

    NASA Astrophysics Data System (ADS)

    1996-04-01

    Huygens will transmit scientific information for 150 minutes, from the outer reaches of Titan's cold atmosphere and all the way down to its enigmatic surface. For comparison, the Jupiter Probe radioed scientific data for 58 minutes as it descended about 200 kilometres into the outer part of the atmosphere of the giant planet. The parachutes controlling various stages of Huygens' descent will rely upon a system for deployment designed and developed in Europe that is nevertheless similar to that used by the Jupiter Probe. The elaborate sequence of operations in Huygens worked perfectly during a dramatic drop test from a stratospheric balloon over Sweden in May 1995, which approximated as closely as possible to events on Titan. The performance of the American Probe at Jupiter renews the European engineers' confidence in their own descent control system, and also in the lithium sulphur-dioxide batteries which were chosen to power both Probes. "The systems work after long storage in space," comments Hamid Hassan, ESA's Project Manager for Huygens. "Huygens will spend seven years travelling to Saturn's vicinity aboard the Cassini Orbiter. The Jupiter Probe was a passenger in Galileo for six years before its release, so there is no reason to doubt that Huygens will work just as well." Huygens will enter the outer atmosphere of Titan at 20,000 kilometres per hour. A heat shield 2.7 metres in diameter will withstand the friction and slow the Probe to a speed at which parachutes can be deployed. The size of the parachute for the main phase of the descent is chosen to allow Huygens to reach the surface in about 2 hours. The batteries powering Huygens will last for about 21/2 hours. Prepared for surprises A different perspective on the Jupiter Probe comes from Jean-Pierre Lebreton, ESA's Project Scientist for Huygens. The results contradicted many preconceptions of the Galileo scientists, particularly about the abundance of water and the structure of cloud layers. Arguments

  8. Observations of Titan IIIC Transtage Fragmentation Debris

    NASA Technical Reports Server (NTRS)

    Cowardin, Heather; Seitzer, P.; Abercromby, K.; Barker, E.; Buckalew, B.; Cardona, T.; Krisko, P.; Lederer, S.

    2013-01-01

    The fragmentation of a Titan IIIC Transtage (1968-081) on 21 February 1992 is one of only two known break-ups in or near geosynchronous orbit. The original rocket body and 24 pieces of debris are currently being tracked by the U. S. Space Surveillance Network (SSN). The rocket body (SSN# 3432) and several of the original fragments (SSN# 25000, 25001, 30000, and 33511) were observed in survey mode during 2004-2010 using the 0.6-m Michigan Orbital DEbris Survey Telescope (MODEST) in Chile using a broad R filter. This paper presents a size distribution for all calibrated magnitude data acquired on MODEST. Size distribution plots are also shown using historical models for small fragmentation debris (down to 10 cm) thought to be associated with the Titan Transtage break-up. In November 2010, visible broadband photometry (Johnson/Kron-Cousins BVRI) was acquired with the 0.9-m Small and Moderate Aperture Research Telescope System (SMARTS) at the Cerro Tololo Inter-American Observatory (CTIO) in Chile on several Titan fragments (SSN 25001, 33509, and 33510) and the parent rocket body (SSN 3432). Color index data are used to determine the fragment brightness distribution and how the data compares to spacecraft materials measured in the laboratory using similar photometric measurement techniques. In order to better characterize the break-up fragments, spectral measurements were acquired on three Titan fragments (one fragment observed over two different time periods) using the 6.5-m Magellan telescopes at Las Campanas Observatory in Chile. The telescopic spectra of SSN 25000 (May 2012 and January 2013), SSN 38690, and SSN 38699 are compared with laboratory acquired spectra of materials (e.g., aluminum and various paints) to determine the surface material.

  9. ANALYSIS OF HARRELL MONOSODIUM TITANATE LOT #46000619120

    SciTech Connect

    Taylor-Pashow, K.

    2012-09-06

    Monosodium titanate (MST) for use in the Actinide Removal Process (ARP) must be qualified and verified in advance. A single qualification sample for each batch of material is sent to SRNL for analysis, as well as a statistical sampling of verification samples. The Harrell Industries Lot #46000619120 qualification and the 13 verification samples met each of the selected specification requirements that were tested and, consequently, the material is acceptable for use in the ARP process.

  10. ANALYSIS OF HARRELL MONOSODIUM TITANATE LOT #052511

    SciTech Connect

    Taylor-Pashow, K.

    2011-08-22

    Monosodium titanate (MST) for use in the Actinide Removal Process (ARP) must be qualified and verified in advance. A single qualification sample for each batch of material is sent to SRNL for analysis, as well as a statistical sampling of verification samples. The Harrell Industries Lot No.052511 qualification and 14 verification samples met all the requirements in the specification indicating the material is acceptable for use in the process.

  11. ANALYSIS OF HARRELL MONOSODIUM TITANATE LOT #071311

    SciTech Connect

    Taylor-Pashow, K.

    2011-10-04

    Monosodium titanate (MST) for use in the Actinide Removal Process (ARP) must be qualified and verified in advance. A single qualification sample for each batch of material is sent to SRNL for analysis, as well as a statistical sampling of verification samples. The Harrell Industries Lot No.071311 qualification and 12 verification samples met all the requirements in the specification indicating the material is acceptable for use in the process.

  12. ANALYSIS OF HARRELL MONOSODIUM TITANATE LOT #46000524120

    SciTech Connect

    Taylor-Pashow, K.

    2012-08-29

    Monosodium titanate (MST) for use in the Actinide Removal Process (ARP) must be qualified and verified in advance. A single qualification sample for each batch of material is sent to SRNL for analysis, as well as a statistical sampling of verification samples. The Harrell Industries Lot No.46000524120 qualification and the 14 verification samples met each of the selected specification requirements that were tested and, consequently, the material is acceptable for use in the ARP process.

  13. Technology evaluation: TriGem, Titan.

    PubMed

    Razis, Evangelia; Fountzilas, George

    2003-04-01

    Titan (formerly Trilex) is developing TriGem, a monoclonal antibody directed against I17, for the potential treatment of advanced cancers that express the GD2 ganglioside, including melanoma, small-cell lung cancer, neuroblastoma and sarcoma. Phase II trials of TriGem for use in advanced melanoma were ongoing by June 2002. TriGem also has potential for the treatment of psoriasis, for which phase II trials had begun by 1996.

  14. Titan 4 TPS Replacement Implementation Study

    NASA Technical Reports Server (NTRS)

    Jackson, Charles H.

    1996-01-01

    This final report documents the overall progress of the study. It is a general discussion of the documents reviewed, recommendations, trips taken, findings/observations, and proposed corrective actions. In addition, cost data for the contract is addressed. The normal abstract and executive summary provided with most final reports is also provided as a part of this report. A conclusion section is provided that addresses the relative completeness of the Titan 4 TPSR project and this contract.

  15. Titan's atmosphere composition: certainties and speculations.

    PubMed

    Gautier, D

    1995-03-01

    Firm results concerning the thermal structure, the composition, the seasonal effects of the atmosphere of Titan, as well as the superotation of its stratosphere are reviewed. The nature of the surface of the satellite, the possible presence of argon in the atmosphere and the structure and composition of clouds and aerosols are, among other topics, still speculative. The implications of the observed deuterium enrichment on the origin of ices in the outer part of the nebula are controversial.

  16. Big Impacts and Transient Oceans on Titan

    NASA Technical Reports Server (NTRS)

    Zahnle, K. J.; Korycansky, D. G.; Nixon, C. A.

    2014-01-01

    We have studied the thermal consequences of very big impacts on Titan [1]. Titan's thick atmosphere and volatile-rich surface cause it to respond to big impacts in a somewhat Earth-like manner. Here we construct a simple globally-averaged model that tracks the flow of energy through the environment in the weeks, years, and millenia after a big comet strikes Titan. The model Titan is endowed with 1.4 bars of N2 and 0.07 bars of CH4, methane lakes, a water ice crust, and enough methane underground to saturate the regolith to the surface. We assume that half of the impact energy is immediately available to the atmosphere and surface while the other half is buried at the site of the crater and is unavailable on time scales of interest. The atmosphere and surface are treated as isothermal. We make the simplifying assumptions that the crust is everywhere as methane saturated as it was at the Huygens landing site, that the concentration of methane in the regolith is the same as it is at the surface, and that the crust is made of water ice. Heat flow into and out of the crust is approximated by step-functions. If the impact is great enough, ice melts. The meltwater oceans cool to the atmosphere conductively through an ice lid while at the base melting their way into the interior, driven down in part through Rayleigh-Taylor instabilities between the dense water and the warm ice. Topography, CO2, and hydrocarbons other than methane are ignored. Methane and ethane clathrate hydrates are discussed quantitatively but not fully incorporated into the model.

  17. Analysis of Harrell Monosodium Titanate Lot #46000824120

    SciTech Connect

    Taylor-Pashow, K. M.L.

    2013-01-23

    Monosodium titanate (MST) for use in the Actinide Removal Process (ARP) must be qualified and verified in advance. A single qualification sample for each batch of material is sent to SRNL for analysis, as well as a statistical sampling of verification samples. The Harrell Industries Lot #46000824120 qualification and the 16 verification samples failed to meet the specification for weight percent solids. All of the pails sampled and tested contained less than 15 wt % MST solids.

  18. Analysis of Harrell Monosodium Titanate Lot #46000908120

    SciTech Connect

    Taylor-Pashow, K. M.L.

    2013-01-23

    Monosodium titanate (MST) for use in the Actinide Removal Process (ARP) must be qualified and verified in advance. A single qualification sample for each batch of material is sent to SRNL for analysis, as well as a statistical sampling of verification samples. The Harrell Industries Lot #46000908120 qualification and the 16 verification samples failed to meet the specification for weight percent solids. All of the pails sampled and tested contained less than 15 wt % MST solids.

  19. Titan's south polar stratospheric vortex evolution

    NASA Astrophysics Data System (ADS)

    Teanby, Nicholas A.; Vinatier, Sandrine; Sylvestre, Melody; de Kok, Remco; Nixon, Conor; Irwin, Patrick Gerard Joseph

    2016-10-01

    Titan experienced northern spring equinox in August 2009 when the south polar region was plunged into perpetual darkness. Following equinox, the south pole experienced the most extreme changes in stratospheric behaviour ever observed: the global stratospheric circulation cell reversed direction (Teanby et al 2012), HCN ice clouds (de Kok et al 2014) and other exotic condensates appeared over the south pole (Jennings et al 2015, West et al 2016), and significant composition and temperature changes occurred (Vinatier et al 2015, Teanby et al 2015, Coustenis et al 2016). Here we use Cassini CIRS limb and nadir observations from 2004-2016 to investigate the evolution of south polar stratospheric temperature and composition in the post-equinox period. Reversal following equinox was extremely rapid, taking less than 6 months (1/60th of a Titan year), which resulted in an initial adiabatic polar hot spot and increased trace gas abundances (Teanby et al 2012). However, rather than develop this trend further as winter progressed, Titan's polar hot spot subsequently disappeared, with the formation of a polar cold spot. Recently in late 2015 / early 2016 a more subdued hotspot began to return with associated extreme trace gas abundances. This talk will reveal the rapid and significant changes observed so far and discuss implications for possible polar feedback mechanisms and Titan's atmospheric dynamics.Coustenis et al (2016), Icarus, 270, 409-420.de Kok et al (2014), Nature, 514, 65-67.Jennings et al (2015), ApJL, 804, L34.Teanby et al (2012), Nature, 491, 732-735.Teanby et al (2015), DPS47, National Harbor, 205.02.Vinatier et al (2015), Icarus, 250, 95-115.West et al (2016), Icarus, 270, 399-408.

  20. Dimming Titan Revealed by the Cassini Observations

    PubMed Central

    Li, Liming

    2015-01-01

    Here we report the temporal variation of Titan's emitted energy with the Cassini/CIRS observations. In the northern hemisphere, the hemispheric-average emitted power decreased from 2007 to 2009 and increased from 2009 to 2012–13, which make the net change insignificant (0.1 ± 0.2%) during the period 2007–2013. The decrease from 2007 to 2009 is mainly due to the cooling around the stratospause, and the increase from 2009 to 2012–13 is probably related to temporal variation of atmospheric temperature around the tropopuase in the northern hemisphere. In the southern hemisphere, the emitted power continuously decreased by 5.0 ± 0.6% from 2.40 ± 0.01 W/m2 in 2007 to 2.28 ± 0.01 in 2012–13, which is mainly related to Titan's seasonal variation. The asymmetry in the temporal variation between the two hemispheres results in the global-average emitted power decreasing by 2.5 ± 0.6% from 2.41 ± 0.01 W/m2 in 2007 to 2.35 ± 0.01 W/m2 in 2012–13. The solar constant at Titan decreased by ~13.0% in the same period 2007–2013, which is much stronger than the temporal variation of emitted power. The measurements of Titan's absorbed solar power are needed to determine the temporal variation of the global energy budget. PMID:25649341

  1. Impact-induced climate change on Titan

    NASA Astrophysics Data System (ADS)

    Zahnle, Kevin; Korycansky, D.

    2012-10-01

    Titan's thick atmosphere and volatile surface cause it to respond to big impacts -- like the one that produced the prominent Menrva impact basin -- in a somewhat Earth-like manner. As a first iteration, we construct a globally-averaged model that tracks the energy released by big comet impacts on a simple Titan with a 1.4 bar N2 atmosphere over a water ice crust, with methane in the atmosphere, in lakes, and saturating the upper (porous) crust. Menrva was big enough to raise the surface temperature by 80 K. If methane in the regolith is generally as abundant as it was at the Huygens landing site, Menrva would have doubled the amount of methane in the atmosphere. The extra methane would have drizzled out of the atmosphere over hundreds of years. Bigger impacts can create shallow liquid water oceans at the surface. If Titan's crust is made of water ice, the putative Hotei impact (a possible 800-1200 km diameter basin, Soderblom et al 2009) would have raised the average surface temperature to 350-400 K. Water rain would have fallen and global meltwaters would have averaged 50 m to as much as 500 m deep. It is appreciated that ice and most hydrocarbons will float on the meltwaters. If water freezes at depths greater than 140 m, methane clathrate is stable and it is likely that methane clathrate forms. Global meltwaters may not have lasted more than a few decades or centuries at most, but are interesting to consider given Titan's organic wealth. Impacts also create local crater lakes set in warm ice but these quickly sink below the warm ice; whether the cryptic waters quickly freeze by mixing with the ice crust or whether they long endure under the ice remains a open question.

  2. Titan on the eve of Voyager encounter

    NASA Technical Reports Server (NTRS)

    Caldwell, J.

    1981-01-01

    A decade of scientific study of Titan is reviewed with emphasis on the composition and the extent of its atmosphere. Several viable models are briefly discussed including the inversion model of Danielsen et al. (1973), Hunten's model (1978) which includes an extensive troposphere and a warm surface, with nitrogen as the major component, and models with neon, primordial carbon monoxide, or various mixtures of hydrogen, helium, and CH4. Recent observations by Pioneer 11 and other satellites are examined.

  3. DETECTION OF PROPENE IN TITAN'S STRATOSPHERE

    SciTech Connect

    Nixon, C. A.; Flasar, F. M.; Jennings, D. E.; Bézard, B.; Vinatier, S.; Coustenis, A.; Teanby, N. A.; Sung, K.; Ansty, T. M.; Irwin, P. G. J.; Gorius, N.; Cottini, V.

    2013-10-10

    The Voyager 1 flyby of Titan in 1980 gave a first glimpse of the chemical complexity of Titan's atmosphere, detecting many new molecules with the infrared interferometer spectrometer (IRIS). These included propane (C{sub 3}H{sub 8}) and propyne (CH{sub 3}C{sub 2}H), while the intermediate-sized C{sub 3}H {sub x} hydrocarbon (C{sub 3}H{sub 6}) was curiously absent. Using spectra from the Composite Infrared Spectrometer on Cassini, we show the first positive detection of propene (C{sub 3}H{sub 6}) in Titan's stratosphere (5σ significance), finally filling the three-decade gap in the chemical sequence. We retrieve a vertical abundance profile from 100-250 km, that varies slowly with altitude from 2.0 ± 0.8 ppbv at 125 km, to 4.6 ± 1.5 ppbv at 200 km. The abundance of C{sub 3}H{sub 6} is less than both C{sub 3}H{sub 8} and CH{sub 3}C{sub 2}H, and we remark on an emerging paradigm in Titan's hydrocarbon abundances whereby alkanes > alkynes > alkenes within the C{sub 2}H {sub x} and C{sub 3}H {sub x} chemical families in the lower stratosphere. More generally, there appears to be much greater ubiquity and relative abundance of triple-bonded species than double-bonded, likely due to the greater resistance of triple bonds to photolysis and chemical attack.

  4. Dimming titan revealed by the Cassini observations.

    PubMed

    Li, Liming

    2015-01-01

    Here we report the temporal variation of Titan's emitted energy with the Cassini/CIRS observations. In the northern hemisphere, the hemispheric-average emitted power decreased from 2007 to 2009 and increased from 2009 to 2012-13, which make the net change insignificant (0.1 ± 0.2%) during the period 2007-2013. The decrease from 2007 to 2009 is mainly due to the cooling around the stratospause, and the increase from 2009 to 2012-13 is probably related to temporal variation of atmospheric temperature around the tropopuase in the northern hemisphere. In the southern hemisphere, the emitted power continuously decreased by 5.0 ± 0.6% from 2.40 ± 0.01 W/m(2) in 2007 to 2.28 ± 0.01 in 2012-13, which is mainly related to Titan's seasonal variation. The asymmetry in the temporal variation between the two hemispheres results in the global-average emitted power decreasing by 2.5 ± 0.6% from 2.41 ± 0.01 W/m(2) in 2007 to 2.35 ± 0.01 W/m(2) in 2012-13. The solar constant at Titan decreased by ~13.0% in the same period 2007-2013, which is much stronger than the temporal variation of emitted power. The measurements of Titan's absorbed solar power are needed to determine the temporal variation of the global energy budget. PMID:25649341

  5. Hardening of Titan's aerosols by their charging

    NASA Astrophysics Data System (ADS)

    Dimitrov, Vasili; Bar-Nun, Akiva

    2003-12-01

    Titan's haze consists of long chain polymers of pure and N-mixed hydrocarbons (Coustenis et al., 1989, Icarus 80, 54-76, 1991, Icarus 89, 152-167). These polymers have regularly alternating (i.e., conjugated) double/single and triple/single bonds, which open either spontaneously (free aging) or under the action of some external factors (forced aging), the latter being very diverse, e.g., charging, photolysis, radiolysis, thermolysis, chemical effect of environment, etc. An essential of free aging was examined previously (Dimitrov and Bar-Nun, 2002, Icarus 156, 530-538). The main distinction between free and any forced aging is that both of them possess the same thermodynamics while different kinetics, the forced aging in any case being faster, proceeding in different pathways than the free aging. The more extensive is the list of the external effects and the more intensive they are, the faster and more variably the forced aging proceeds. In this paper we quantified the kinetics of forced aging, considering charging of Titan's aerosol population. It was found that forced aging proceeds approximately hundred times faster as compared to the free aging. Various physico-chemical properties of Titan's aerosol material, including coagulation coefficients, depending on particle size and medium conditions, were defined. The comparison of the aging rate, rate of sedimentation and rate of the particle increase proves that Titan's aerosol domain can be subdivided conditionally into two big subdomains. The upper one contains minor portion (<5%) of the total aerosol bulk, unannealed aerosol particles being fine and sticky. The lower subdomain contains the major portion (>95%) of aerosol bulk, which is completely aged, coarsely dispersed particles. We established the border between these subdomains at the altitude Z˜620 km.

  6. Scalable descriptive and correlative statistics with Titan.

    SciTech Connect

    Thompson, David C.; Pebay, Philippe Pierre

    2008-12-01

    This report summarizes the existing statistical engines in VTK/Titan and presents the parallel versions thereof which have already been implemented. The ease of use of these parallel engines is illustrated by the means of C++ code snippets. Furthermore, this report justifies the design of these engines with parallel scalability in mind; then, this theoretical property is verified with test runs that demonstrate optimal parallel speed-up with up to 200 processors.

  7. The dynamics behind Titan's methane clouds

    PubMed Central

    Mitchell, Jonathan L.; Pierrehumbert, Raymond T.; Frierson, Dargan M. W.; Caballero, Rodrigo

    2006-01-01

    We present results of an axisymmetric global circulation model of Titan with a simplified suite of atmospheric physics forced by seasonally varying insolation. The recent discovery of midlatitude tropospheric clouds on Titan has caused much excitement about the roles of surface sources of methane and the global circulation in forming clouds. Although localized surface sources, such as methane geysers or “cryovolcanoes,” have been invoked to explain these clouds, we find in this work that clouds appear in regions of convergence by the mean meridional circulation and over the poles during solstices, where the solar forcing reaches its seasonal maximum. Other regions are inhibited from forming clouds because of dynamical transports of methane and strong subsidence. We find that for a variety of moist regimes, i.e., with the effect of methane thermodynamics included, the observed cloud features can be explained by the large-scale dynamics of the atmosphere. Clouds at the solsticial pole are found to be a robust feature of Titan's dynamics, whereas isolated midlatitude clouds are present exclusively in a variety of moist dynamical regimes. In all cases, even without including methane thermodynamics, our model ceases to produce polar clouds ≈4–6 terrestrial years after solstices. PMID:17121992

  8. Characterization of clouds in Titan's tropical atmosphere

    USGS Publications Warehouse

    Griffith, C.A.; Penteado, P.; Rodriguez, S.; Le, Mouelic S.; Baines, K.H.; Buratti, B.; Clark, R.; Nicholson, P.; Jaumann, R.; Sotin, C.

    2009-01-01

    Images of Titan's clouds, possible over the past 10 years, indicate primarily discrete convective methane clouds near the south and north poles and an immense stratiform cloud, likely composed of ethane, around the north pole. Here we present spectral images from Cassini's Visual Mapping Infrared Spectrometer that reveal the increasing presence of clouds in Titan's tropical atmosphere. Radiative transfer analyses indicate similarities between summer polar and tropical methane clouds. Like their southern counterparts, tropical clouds consist of particles exceeding 5 ??m. They display discrete structures suggestive of convective cumuli. They prevail at a specific latitude band between 8??-20?? S, indicative of a circulation origin and the beginning of a circulation turnover. Yet, unlike the high latitude clouds that often reach 45 km altitude, these discrete tropical clouds, so far, remain capped to altitudes below 26 km. Such low convective clouds are consistent with the highly stable atmospheric conditions measured at the Huygens landing site. Their characteristics suggest that Titan's tropical atmosphere has a dry climate unlike the south polar atmosphere, and despite the numerous washes that carve the tropical landscape. ?? 2009. The American Astronomical Society.

  9. High Performance Radiation Transport Simulations on TITAN

    SciTech Connect

    Baker, Christopher G; Davidson, Gregory G; Evans, Thomas M; Hamilton, Steven P; Jarrell, Joshua J; Joubert, Wayne

    2012-01-01

    In this paper we describe the Denovo code system. Denovo solves the six-dimensional, steady-state, linear Boltzmann transport equation, of central importance to nuclear technology applications such as reactor core analysis (neutronics), radiation shielding, nuclear forensics and radiation detection. The code features multiple spatial differencing schemes, state-of-the-art linear solvers, the Koch-Baker-Alcouffe (KBA) parallel-wavefront sweep algorithm for inverting the transport operator, a new multilevel energy decomposition method scaling to hundreds of thousands of processing cores, and a modern, novel code architecture that supports straightforward integration of new features. In this paper we discuss the performance of Denovo on the 10--20 petaflop ORNL GPU-based system, Titan. We describe algorithms and techniques used to exploit the capabilities of Titan's heterogeneous compute node architecture and the challenges of obtaining good parallel performance for this sparse hyperbolic PDE solver containing inherently sequential computations. Numerical results demonstrating Denovo performance on early Titan hardware are presented.

  10. Amino acids derived from Titan Tholins

    NASA Astrophysics Data System (ADS)

    Khare, Bishun N.; Sagan, Carl; Ogino, Hiroshi; Nagy, Bartholomew; Er, Cevat; Schram, Karl H.; Arakawa, Edward T.

    1986-10-01

    An organic heteropolymer(Titan tholin) was produced by continuous dc discharge through a 0.9 N 2/0.1 CH 4 gas mixture at 0.2 mbar pressure, roughly simulating the cloudtop atmosphere of Titan. Treatment of this tholin with 6 N HCI yielded 16 amino acids by gas chromatography after derivazation to N-trifluroacetyl isopropyl esters on two different capillary columns. Identifications were confirmed by GC/MS. Glycine, aspartic acid, and α- and β-alanine were produced in greatest abundance; the total yield of amino acids was ˜ 10 -2, approximately equal to the yield of urea. The presence of "nonbiological" amino acids, the absence of serine, and the fact that the amino acids are racemic within experimental error together indicate that these molecules are not due to microbial or other contamination, but are derived from the tholin. In addition to the HCN, HC 2CN, and (CN) 2 found by Voyager, nitriles and aminonitriles should be sought in the Titanian atmosphere and, eventually, amino acids on the surface. These results suggest that episodes of liquid water in the past or future of Titan might lead to major further steps in prebiological organic chemistry on that body.

  11. High Altitude Synthetic Aperture Imaging of Titan

    NASA Astrophysics Data System (ADS)

    West, Richard; Stiles, B.; Anderson, Y.; Boehmer, R.; Callahan, P.; Gim, Y.; Hamilton, G.; Johnson, W. T.; Kelleher, K.; Wye, L.; Zebker, H.

    2006-09-01

    The Cassini spacecraft has been conducting observations of Titan since July 2004 . Currently, 6 close flyby's have collected synthetic aperture radar (SAR) data giving image resolutions down to 300 - 500 m. About 14 additional close radar imaging passes are planned. To improve radar coverage and increase the synergy with other Cassini imaging instruments such as VIMS and ISS, the radar team has started experimenting with very high altitude SAR imaging where conditions permit. This presentation will examine the performance trade-offs, special processing issues, and science potential of these high altitude SAR observations. These data collections are distinct from the normal Titan SAR images because the range will be much larger (around 20,000 km). To acquire enough signal in these circumstances, the radar operates in the lowest bandwidth scatterometer mode while spacecraft pointing control is used to slowly pan the central beam across a small swath. Due to a lower signal to noise ratio these high altitude images are designed to average together 150-200 independent looks to see features that may lie below the noise floor. So far, three high altitude images have been acquired during Titan flyby's T12, T13, and T15. In T12 imaging was attempted from 37000 km with an effective resolution around 5 km. In T13 the Huygens Probe landing site was imaged from 11000 km with effective resolution of 1 - 2 km. In T15 the Tsegehi area was imaged from 20000 km with effective resolution of 2 - 3 km.

  12. The dynamics behind Titan's methane clouds.

    PubMed

    Mitchell, Jonathan L; Pierrehumbert, Raymond T; Frierson, Dargan M W; Caballero, Rodrigo

    2006-12-01

    We present results of an axisymmetric global circulation model of Titan with a simplified suite of atmospheric physics forced by seasonally varying insolation. The recent discovery of midlatitude tropospheric clouds on Titan has caused much excitement about the roles of surface sources of methane and the global circulation in forming clouds. Although localized surface sources, such as methane geysers or "cryovolcanoes," have been invoked to explain these clouds, we find in this work that clouds appear in regions of convergence by the mean meridional circulation and over the poles during solstices, where the solar forcing reaches its seasonal maximum. Other regions are inhibited from forming clouds because of dynamical transports of methane and strong subsidence. We find that for a variety of moist regimes, i.e., with the effect of methane thermodynamics included, the observed cloud features can be explained by the large-scale dynamics of the atmosphere. Clouds at the solsticial pole are found to be a robust feature of Titan's dynamics, whereas isolated midlatitude clouds are present exclusively in a variety of moist dynamical regimes. In all cases, even without including methane thermodynamics, our model ceases to produce polar clouds approximately 4-6 terrestrial years after solstices.

  13. Amino acids derived from Titan tholins

    NASA Technical Reports Server (NTRS)

    Khare, B. N.; Sagan, C.; Ogino, H.; Nagy, B.; Er, C.; Schram, K. H.; Arakawa, E. T.

    1986-01-01

    An organic heteropolymer (Titan tholin) was produced by continuous dc discharge through a 0.9 N2/0.1 CH4 gas mixture at 0.2 mbar pressure, roughly simulating the cloudtop atmosphere of Titan. Treatment of this tholin with 6N HCl yielded 16 amino acids by gas chromatography after derivatization of N-trifluroacetyl isopropyl esters on two different capillary columns. Identifications were confirmed by GC/MS. Glycine, aspartic acid, and alpha- and beta-alanine were produced in greatest abundance; the total yield of amino acids was approximately 10(-2), approximately equal to the yield of urea. The presence of "nonbiological" amino acids, the absence of serine, and the fact that the amino acids are racemic within experimental error together indicate that these molecules are not due to microbial or other contamination, but are derived from the tholin. In addition to the HCN, HC2CN, and (CN)2 found by Voyager, nitriles and aminonitriles should be sought in the Titanian atmosphere and, eventually, amino acids on the surface. These results suggest that episodes of liquid water in the past or future of Titan might lead to major further steps in prebiological organic chemistry on that body.

  14. Constraining and Interpreting Titan's Methane Hydrologic Cycle

    NASA Astrophysics Data System (ADS)

    Lora, Juan; Mitchell, Jonathan; Adamkovics, Mate

    2016-06-01

    Titan's surface supports large reservoirs of stable hydrocarbon liquids, while active weather and a seasonal cycle operate in the troposphere. Titan's hydrologic cycle transports methane between the atmosphere, the surface, and, potentially, the sub-surface on various timescales. Yet the detailed distribution of methane both in the lower atmosphere and in the surface is essentially unknown, though studies of the processes that control it, from seasonal to orbital timescales, are now relatively mature. Many conundrums remain regarding observed hydrologic phenomena. For example, why have widely-expected cloud outbursts at the North pole failed to materialize? Why are there extensive fluvial surface features at the dry low latitudes? Using a combination of general circulation, radiative transfer, and surface modeling, in conjunction with ground-based and Cassini observations, we are working to better characterize and predict tropospheric cloud occurrence, measure and interpret the variability of lower-atmosphere humidity, and clarify the distribution of lakes and surface features and their connection to the atmosphere. Within this context, I will summarize our efforts to improve our understanding of the atmospheric circulation, dynamics, and surface-atmosphere interactions that affect the hydrologic cycle, to gain a better insight into Titan's climate system and its evolution.

  15. Cassini RADARs Penultimate Passes by Titan

    NASA Astrophysics Data System (ADS)

    Wall, Stephen D.; Cassini RADAR Science Team

    2016-10-01

    The Cassini spacecraft will be in its final year of operation as you read this abstract. The RADAR instrument will observe Titan on passes that occur (or occurred) June 27 (T120), July 25 (T121) and April 22, 2017 (T126), all including SAR imaging. T120 SAR, the only pass received at this writing, has revealed what is arguably the best example of Labrynthic terrain, a unit previously identified on about 2% of the observed surface of Titan (Lopes et al., 2016); extended our observations of "cookie cutter lakes" seen in SAR the very dark area described by Griffith et al (2012), and given added context to the equatorial wind-streak features (Malaska, 2016). The T121 SAR swath promises similar exciting data as it observes Hotei Regio, an area previously thought to be a candidate cryovolcano; Tui Regio (Barnes et al., 2006); and a last look at Xanadu's eastern flanks. We will review all new findings on T120 and T121 and also preview T126 SAR, where we will get a last look at the northern seas, including Titan's "Magic Island" (Hofgartner et al., 2015).This work was carried out at the Jet Propulsion Laboratory, California Insititue of Technology, under a contract with the National Aeronautics and Space Administration.

  16. Organic synthesis in the atmosphere of Titan

    NASA Astrophysics Data System (ADS)

    Gupta, S. K.; Ochiai, E.; Ponnamperuma, C.

    1981-10-01

    Experimental simulations of organic chemistry taking place in the atmosphere of Titan are presented in light of the recent atmospheric composition data provided by the Voyager spacecraft. In the experiments, a gas mixture of N2 and CH4 in proportions from about 100:1 to 100:4 was irradiated by UV radiation, electric discharges, an electron beam, gamma radiation and a proton beam to assess the possible contributions of the various possible energy sources to atmospheric chemistry on Titan. Analysis of reaction products by GC/MS reveals UV light to produce saturated hydrocarbons such as C2H6 and C3H8 but no appreciable amounts of unsaturated hydrocarbons or nitrogen-containing compounds. Electric discharges and gamma, beta and proton radiation, however, are found to produce HCN and more unsaturated than saturated hydrocarbons. Acetylene is believed to be produced from ethane or ethylene in methanephotolysis, while HCN may be produced from CH2 radicals. The presence of HCN on Titan is interpreted as implying that the chemical processes postulated as involved in the formation of bases and amino acids on the primitive earth may be common in the solar system.

  17. Liquid Ethane and Methane on Titan

    NASA Astrophysics Data System (ADS)

    Clark, Roger Nelson; Curchin, J.; Brown, R. H.; Barnes, J. W.; Jaumann, R.; Soderblom, L.; Cruikshank, D. P.; Lunine, J.; Stephan, K.; Hoefen, T. H.; Le Mouelic, S.; Sotin, C.; Baines, K.; Buratti, B.; Nicholson, P.

    2008-09-01

    Absorption coefficients for liquid methane and ethane were derived in a 1-bar nitrogen atmosphere at 90K. Ethane and methane were condensed in an aluminum sample cup, and a 2-way transmission spectrum was measured. Different path lengths up to 14 mm allowed a wide range of absorption coefficients to be measured, and covered the range needed to compare to spectra of Titan in the 1- to 5-micron atmospheric windows. The data were used to compute possible liquid absorption in spectra from the Cassini Visual and Infrared Mapping Spectrometer (VIMS) and were compared to global VIMS data for Titan. The laboratory data show that both liquid methane and ethane have a strong absorption band near 4.97 microns that is detectable by VIMS. A liquid lake thickness of 3 mm (6 mm path length) would result in an absorption band depth of about 65% for methane and 85% for ethane. Ethane has a 2.02-micron absorption with a strength similar to the 4.97-micron absorption, and methane has an absorption that is 10x weaker. Continuum absorption would result in the following surface reflectance levels (at VIMS wavelengths and resolution). Examining VIMS Titan data, we find that for most of the surface, we detect no liquid methane or ethane. In a few locations VIMS data indicate liquid methane or ethane, but at less than about 1-mm total path length.

  18. Low Temperature Reflectance Spectra of Titan Tholins

    NASA Technical Reports Server (NTRS)

    Roush, T. L.; Dalton, J. B.; Fonda, Mark (Technical Monitor)

    2001-01-01

    Compositional interpretation of remotely obtained reflectance spectra of outer solar system surfaces is achieved by a variety of methods. These include matching spectral curves, matching spectral features, quantitative spectral interpretation, and theoretical modeling of spectra. All of these approaches rely upon laboratory measurements of one kind or another. The bulk of these laboratory measurements are obtained with the sample of interest at ambient temperatures and pressures. However, surface temperatures of planets, satellites, and asteroids in the outer solar system are significantly cooler than ambient laboratory conditions on Earth. The infrared spectra of many materials change as a function of temperature. As has been recently demonstrated it is important to assess what effects colder temperatures have on spectral properties and hence, compositional interpretations. Titan tholin is a solid residue created by energetic processing of H-, C-, and N-bearing gases. Such residues can also be created by energetic processing if the gases are condensed into ices. Titan tholin has been suggested as a coloring agent for several surfaces in the outer solar system. Here we report laboratory measurements of Titan tholin at a temperature of 100 K and compare these to measurements of the same sample near room temperature. At low temperature the absorption features beyond 1 micrometer narrow slightly. At wavelengths greater than approx. 0.8 micrometer the overall reflectance of the sample decreases slightly making the sample less red at low temperatures. We will discuss the implications of the laboratory measurements for interpretation of cold outer solar system surfaces.

  19. Titan's Surface Temperatures Measured by Cassini CIRS

    NASA Technical Reports Server (NTRS)

    Jennings, Donald E.; Flasar, F. M.; Kundle, V. G.; Samuelson, R. E.; Pearl, J. C.; Nixon, C. A.; Carlson, R. C.; Mamoutkine, A. A.; Brasunas, J. C.; Guandique, E.; Arhterberg, R. K.; Bjoraker, G. L.; Romani, P. N.; Segura, M. E.; Albright, S. A.; Elliott, M. H.; Tingley, J. S.; Calcutt, S.; Coustenis, A.; Bezard, B.; Courtin, R.

    2008-01-01

    A large fraction of 19-micron thermal radiation from the surface of Titan reaches space through a spectral window of low atmospheric opacity. The emergent radiance, after removing the effect of the atmosphere, gives the brightness temperature of the surface. This atmospheric window is covered by the far-infrared channel of the Composite Infrared spectrometer1 (CIRS) on Cassini. In mapping Titan surface temperatures, CIRS is able to improve upon results of Voyager IRIS, by taking advantage of improved latitude coverage and a much larger dataset. Observations are from a wide range of emission angles and thereby provide constraints on the atmospheric opacity and radiance that are used to derive the surface temperature. CIRS finds an average equatorial surface brightness temperature of 93.7+/-0.6 K, virtually identical to the HASI temperature at the Huygens landing site. Mapping in latitude shows that the surface temperature decreases toward the poles by about 2 K in the south and 3 K in the north. This surface temperature distribution is consistent with the formation of lakes seen at high latitudes on Titan.

  20. Titan's Surface Temperatures from Cassini CIRS

    NASA Technical Reports Server (NTRS)

    Jennings, Donald E.; Cottini, Valeria; Nixon, Conor A.

    2010-01-01

    The surface brightness temperature of Titan can be measured from Cassini through a spectral window at 19 microns where the atmosphere is low in opacity. The Composite Infrared Spectrometer (CIRS) on Cassini observes this wavelength in its far-infrared channel. Because the Cassini tour has provided global coverage and a range of viewing geometries, CIRS has been able to go beyond the earlier flyby results of Voyager IRIS Near the equator, CIRS measures the zonally-averaged surface brightness temperature to be 917 K, very close to the temperature found at the surface by Huygens. Latitude maps show that Titan's surface temperatures drop off by about 2 K toward the south and by about 3 K toward the north. This temperature distribution is consistent with Titan's late northern winter when the data were taken. As the seasons progress, CIRS is continuing to search for corresponding changes in the temperatures of the surface and lower atmosphere. CIRS is also extending global mapping to both latitude and longitude to look for correlations between surface temperatures and geological features.

  1. Impact-Induced Climate Change on Titan

    NASA Technical Reports Server (NTRS)

    Zahnle, Kevin; Korycansky, Donald

    2012-01-01

    Titan's thick atmosphere and volatile surface cause it to respond to big impacts like the one that produced the prominent Menrva impact basin in a somewhat Earth-like manner. Menrva was big enough to raise the surface temperature by 100 K. If methane in the regolith is generally as abundant as it was at the Huygens landing site, Menrva would have been big enough to double the amount of methane in the atmosphere. The extra methane would have drizzled out of the atmosphere over hundreds of years. Conditions may have been favorable for clathrating volatiles such as ethane. Impacts can also create local crater lakes set in warm ice but these quickly sink below the warm ice; whether the cryptic waters quickly freeze by mixing with the ice crust or whether they long endure under the ice remains a open question. Bigger impacts can create shallow liquid water oceans at the surface. If Titan's crust is made of water ice, the putative Hotei impact (a possible 800-1200 km diameter basin, Soderblom et al 2009) would have raised the average surface temperature to 350-400 K. Water rain would have fallen and global meltwaters would have averaged 50 m to as much as 500 m deep. The meltwaters may not have lasted more than a few decades or centuries at most, but are interesting to consider given Titan's organic wealth.

  2. The key to Mars, Titan and beyond

    SciTech Connect

    Zubrin, R.M. )

    1990-06-01

    This paper discusses the use of nuclear rockets using indigenous Mars propellants for future missions to Mars and Titan, which would drastically reduce the mass and cost of the mission while increasing its capability. Special attention is given to the CO2-powered nuclear rocket using indigenous Martian fuel (NIMF) vehicle for hopping around on Mars. If water is available on Mars, it could make a NIMF propellant yielding an exhaust velocity of 3.4 km/sec, good enough to allow a piloted NIMF spacecraft to ascent from the surface of Mars and propel itself directly to LEO; if water is available on Phobos, a NIMF spacecraft could travel to earth orbit and then back to Phobos or Mars without any additional propellant from earth. One of the many exciting missions beyond Mars that will be made possible by NIMF technology is the exploration of Saturn's moon Titan. A small automated NIMF Titan explorer, with foldout wings and a NERVA (Nuclear Engine for Rocket Vehicle Applications) engine, is proposed.

  3. Thermal decomposition of bioactive sodium titanate surfaces

    NASA Astrophysics Data System (ADS)

    Ravelingien, Matthieu; Mullens, Steven; Luyten, Jan; Meynen, Vera; Vinck, Evi; Vervaet, Chris; Remon, Jean Paul

    2009-09-01

    Alkali-treated orthopaedic titanium surfaces have earlier shown to induce apatite deposition. A subsequent heat treatment under air improved the adhesion of the sodium titanate layer but decreased the rate of apatite deposition. Furthermore, insufficient attention was paid to the sensitivity of titanium substrates to oxidation and nitriding during heat treatment under air. Therefore, in the present study, alkali-treated titanium samples were heat-treated under air, argon flow or vacuum. The microstructure and composition of their surfaces were characterized to clarify what mechanism is responsible for inhibiting in vitro calcium phosphate deposition after heat treatment. All heat treatments under various atmospheres turned out to be detrimental for apatite deposition. They led to the thermal decomposition of the dense sodium titanate basis near the interface with the titanium substrate. Depending on the atmosphere, several forms of Ti yO z were formed and Na 2O was sublimated. Consequently, less exchangeable sodium ions remained available. This pointed to the importance of the ion exchange capacity of the sodium titanate layer for in vitro bioactivity.

  4. Determining Atmospheric-Density Profile of Titan

    NASA Technical Reports Server (NTRS)

    Sarani, Siamak

    2010-01-01

    A method was developed for measuring the atmospheric density of Titan, the largest moon of Saturn, to create an accurate density profile as a function of altitude. This will allow mission planners to select safe flyby altitudes, and for navigation engineers to accurately predict the delta-v associated with those flybys. The spacecraft angular rate vector profile as a function of time is collected via telemetry from the onboard attitude estimator once every 2 seconds. The telemetry for thruster times, as a function of time, for eight Reaction Control System (RCS) thrusters is gathered, once a second, from the Propulsion Manager algorithm of the Cassini onboard attitude-control flight software. Using these data, the ground software computes the angular momentum vector profile and the per-axis external torque as a function of time imparted from the spacecraft only due to the atmospheric drag. The software can then determine the Titan atmospheric density profile as a function of time and altitude with the known values of spacecraft center of mass, the Titan-relative range and velocity data, the projected area, and the aerocenter, along with the estimated drag coefficient in a free molecular flow field.

  5. Current hot potatoes in atrial fibrillation ablation.

    PubMed

    Roten, Laurent; Derval, Nicolas; Pascale, Patrizio; Scherr, Daniel; Komatsu, Yuki; Shah, Ashok; Ramoul, Khaled; Denis, Arnaud; Sacher, Frédéric; Hocini, Mélèze; Haïssaguerre, Michel; Jaïs, Pierre

    2012-11-01

    Atrial fibrillation (AF) ablation has evolved to the treatment of choice for patients with drug-resistant and symptomatic AF. Pulmonary vein isolation at the ostial or antral level usually is sufficient for treatment of true paroxysmal AF. For persistent AF ablation, drivers and perpetuators outside of the pulmonary veins are responsible for AF maintenance and have to be targeted to achieve satisfying arrhythmia-free success rate. Both complex fractionated atrial electrogram (CFAE) ablation and linear ablation are added to pulmonary vein isolation for persistent AF ablation. Nevertheless, ablation failure and necessity of repeat ablations are still frequent, especially after persistent AF ablation. Pulmonary vein reconduction is the main reason for arrhythmia recurrence after paroxysmal and to a lesser extent after persistent AF ablation. Failure of persistent AF ablation mostly is a consequence of inadequate trigger ablation, substrate modification or incompletely ablated or reconducting linear lesions. In this review we will discuss these points responsible for AF recurrence after ablation and review current possibilities on how to overcome these limitations. PMID:22920482

  6. Ferroelastic domains in lead-free barium zirconate titanate - barium calcium titanate piezoceramics

    NASA Astrophysics Data System (ADS)

    Ehmke, Matthias Claudius

    Piezoelectricity was first discovered by Pierre and Jaque Curie in the year 1880. Nowadays, piezoelectric materials are used in many application such as high voltage generation in gas igniters, actuation in micro-positioning devices, generation and detection of acoustic waves, emitters and receivers for sonar technology, ultrasonic cleaning, ultrasound medical therapy, and micropumps for ink-jet printers. The most commonly used piezoelectric material since the 1950's is the solid solution system lead zirconate titanate (PZT) that offers high piezoelectric performance under a large range of operating conditions. However, the toxicity of lead requires the replacement of PZT. The studied lead-free alternatives are commonly based on potassium sodium niobate (KNN) and bismuth sodium titanate (BNT), and more recently zirconium and calcium substituted barium titanate (BZT-BCT). The BZT-BCT system exhibits large piezoelectric coefficients that can exceed even those of most PZT compositions under certain conditions. Piezoelectricity was first discovered by Pierre and Jaque Curie in the year 1880. Nowadays, piezoelectric materials are used in many application such as high voltage generation in gas igniters, actuation in micro-positioning devices, generation and detection of acoustic waves, emitters and receivers for sonar technology, ultrasonic cleaning, ultrasound medical therapy, and micropumps for ink-jet printers. The most commonly used piezoelectric material since the 1950's is the solid solution system lead zirconate titanate (PZT) that offers high piezoelectric performance under a large range of operating conditions. However, the toxicity of lead requires the replacement of PZT. The studied lead-free alternatives are commonly based on potassium sodium niobate (KNN) and bismuth sodium titanate (BNT), and more recently zirconium and calcium substituted barium titanate (BZT-BCT). The BZT-BCT system exhibits large piezoelectric coefficients that can exceed even those of

  7. Titan Topography: A Comparison Between Cassini Altimeter and SAR Imaging from Two Titan Flybys

    NASA Astrophysics Data System (ADS)

    Gim, Y.; Stiles, B.; Callahan, P. S.; Johnson, W. T.; Hensley, S.; Hamilton, G.; West, R.; Alberti, G.; Flamini, E.; Lorenz, R. D.; Zebker, H. A.; Cassini RADAR Team

    2007-12-01

    The Cassini RADAR has collected twelve altimeter data sets of Titan since the beginning of the Saturn Tour in 2004. Most of the altimeter measurements were made at high altitudes, from 4,000 km to 15,000 km, resulting in low spatial resolutions due to beam footprint sizes larger than 20 km, as well as short ground tracks less than 600 km. One flyby (T30) was dedicated to altimeter data collection from 15,000 km to the closest approach altitude of 950 km. This produced a beam footprint size of 6 km at the lowest altitude and an altimeter ground track of about 3,500 km covering Titan's surface from near the equator to high latitude areas near Titan's north pole. More importantly, the ground track is located inside the SAR swath viewed from an earlier Titan flyby (T28). This provides a rare opportunity to investigate Titan topography with a relatively high spatial resolution and compare nadir-looking altimeter data with side-looking SAR imaging. From altimeter data, we have measured the mean Titan radius of 2575.1 km +/- 0.1 km and observed rather complex topographical variations over a short distance. By comparing altimeter data and SAR images at altitudes below 2,000 km, we have found that there is a strong correlation between SAR brightness and altimeter waveform; SAR dark areas correspond to strong and sharp altimeter waveforms while SAR bright areas correspond to weak and diffused altimeter waveforms. The research described here was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

  8. Femtosecond laser ablation of enamel

    NASA Astrophysics Data System (ADS)

    Le, Quang-Tri; Bertrand, Caroline; Vilar, Rui

    2016-06-01

    The surface topographical, compositional, and structural modifications induced in human enamel by femtosecond laser ablation is studied. The laser treatments were performed using a Yb:KYW chirped-pulse-regenerative amplification laser system (560 fs and 1030 nm) and fluences up to 14 J/cm2. The ablation surfaces were studied by scanning electron microscopy, grazing incidence x-ray diffraction, and micro-Raman spectroscopy. Regardless of the fluence, the ablation surfaces were covered by a layer of resolidified material, indicating that ablation is accompanied by melting of hydroxyapatite. This layer presented pores and exploded gas bubbles, created by the release of gaseous decomposition products of hydroxyapatite (CO2 and H2O) within the liquid phase. In the specimen treated with 1-kHz repetition frequency and 14 J/cm2, thickness of the resolidified material is in the range of 300 to 900 nm. The micro-Raman analysis revealed that the resolidified material contains amorphous calcium phosphate, while grazing incidence x-ray diffraction analysis allowed detecting traces of a calcium phosphate other than hydroxyapatite, probably β-tricalcium phosphate Ca3), at the surface of this specimen. The present results show that the ablation of enamel involves melting of enamel's hydroxyapatite, but the thickness of the altered layer is very small and thermal damage of the remaining material is negligible.

  9. Femtosecond laser ablation of enamel

    NASA Astrophysics Data System (ADS)

    Le, Quang-Tri; Bertrand, Caroline; Vilar, Rui

    2016-06-01

    The surface topographical, compositional, and structural modifications induced in human enamel by femtosecond laser ablation is studied. The laser treatments were performed using a Yb:KYW chirped-pulse-regenerative amplification laser system (560 fs and 1030 nm) and fluences up to 14 J/cm2. The ablation surfaces were studied by scanning electron microscopy, grazing incidence x-ray diffraction, and micro-Raman spectroscopy. Regardless of the fluence, the ablation surfaces were covered by a layer of resolidified material, indicating that ablation is accompanied by melting of hydroxyapatite. This layer presented pores and exploded gas bubbles, created by the release of gaseous decomposition products of hydroxyapatite (CO2 and H2O) within the liquid phase. In the specimen treated with 1-kHz repetition frequency and 14 J/cm2, thickness of the resolidified material is in the range of 300 to 900 nm. The micro-Raman analysis revealed that the resolidified material contains amorphous calcium phosphate, while grazing incidence x-ray diffraction analysis allowed detecting traces of a calcium phosphate other than hydroxyapatite, probably β-tricalcium phosphate Ca3), at the surface of this specimen. The present results show that the ablation of enamel involves melting of enamel's hydroxyapatite, but the thickness of the altered layer is very small and thermal damage of the remaining material is negligible.

  10. Laser ablation studies of concrete

    SciTech Connect

    Savina, M.; Xu, Z.; Wang, Y.; Reed, C.; Pellin, M.

    1999-10-20

    Laser ablation was studied as a means of removing radioactive contaminants from the surface and near-surface regions of concrete. The authors present the results of ablation tests on cement and concrete samples using a 1.6 kW pulsed Nd:YAG laser with fiber optic beam delivery. The laser-surface interaction was studied using cement and high density concrete as targets. Ablation efficiency and material removal rates were determined as functions of irradiance and pulse overlap. Doped samples were also ablated to determine the efficiency with which surface contaminants were removed and captured in the effluent. The results show that the cement phase of the material melts and vaporizes, but the aggregate portion (sand and rock) fragments. The effluent consists of both micron-size aerosol particles and chunks of fragmented aggregate material. Laser-induced optical emission spectroscopy was used to analyze the surface during ablation. Analysis of the effluent showed that contaminants such as cesium and strontium were strongly segregated into different regions of the particle size distribution of the aerosol.

  11. Fragmentation and ablation during entry

    SciTech Connect

    Canavan, G.H.

    1997-09-01

    This note discusses objects that both fragment and ablate during entry, using the results of previous reports to describe the velocity, pressure, and fragmentation of entering objects. It shows that the mechanisms used there to describe the breakup of non-ablating objects during deceleration remain valid for most ablating objects. It treats coupled fragmentation and ablation during entry, building on earlier models that separately discuss the entry of objects that are hard, whose high heat of ablation permits little erosion, and those who are strong whose strength prevents fragmentation, which are discussed in ``Radiation from Hard Objects,`` ``Deceleration and Radiation of Strong, Hard, Asteroids During Atmospheric Impact,`` and ``Meteor Signature Interpretation.`` This note provides a more detailed treatment of the further breakup and separation of fragments during descent. It replaces the constraint on mass per unit area used earlier to determine the altitude and magnitude of peak power radiation with a detailed analytic solution of deceleration. Model predictions are shown to be in agreement with the key features of numerical calculations of deceleration. The model equations are solved for the altitudes of maximum radiation, which agree with numerical integrations. The model is inverted analytically to infer object size and speed from measurements of peak power and altitude to provide a complete model for the approximate inversion of meteor data.

  12. Hydrothermal synthesis map of bismuth titanates

    SciTech Connect

    Sardar, Kripasindhu; Walton, Richard I.

    2012-05-15

    The hydrothermal synthesis of four bismuth titanate materials from common bismuth and titanium precursors under hydrothermal conditions is described. Reaction of NaBiO{sub 3}{center_dot}2H{sub 2}O and anatase TiO{sub 2} in concentrated NaOH solution at 240 Degree-Sign C is shown to produce perovskite and sillenite phases Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} and Bi{sub 12}TiO{sub 20}, depending on the ratio of metal precursors used. When KOH solution is used and a 1:1 ratio of the same precursors, a pyrochlore Bi{sub 1.43}Ti{sub 2}O{sub 6}(OH){sub 0.29}(H{sub 2}O){sub 0.66} is formed. The use of a mixture of HNO{sub 3} and NaOH is shown to facilitate the formation of the Aurivillius-type bismuth titanate Bi{sub 4}Ti{sub 3}O{sub 12}. The phases have been isolated separately as phase-pure powders and profile refinement of powder X-ray diffraction data allows comparisons with comparable materials reported in the literature. Analysis of Bi L{sub III}-edge X-ray absorption near edge structure (XANES) spectra of the materials shows the oxidation state of bismuth is +3 in all of the hydrothermally derived products. - Graphical abstract: Use of NaBiO{sub 3}{center_dot}2H{sub 2}O and TiO{sub 2} as reagents under hydrothermal conditions allows the phase-pure preparation of four crystalline bismuth titanate materials. Highlights: Black-Right-Pointing-Pointer NaBiO{sub 3} and TiO{sub 2} under hydrothermal conditions allow formation of bismuth titanates. Black-Right-Pointing-Pointer Synthesis of four distint phases has been mapped. Black-Right-Pointing-Pointer Bi LIII-edge XANES shows Bi is reduced to oxidation state +3 in all materials. Black-Right-Pointing-Pointer A new hydrated bismuth titanate pyrochlore has been isolated.

  13. Aromatic Structure in Simulates Titan Aerosol

    NASA Technical Reports Server (NTRS)

    Trainer, Melissa G.; Loeffler, M. J.; Anderson, C. M.; Hudson, R. L.; Samuelson, R. E.; Moore, M. A.

    2011-01-01

    Observations of Titan by the Cassini Composite Infrared Spectrometer (CIRS) between 560 and 20 per centimeter (approximately 18 to 500 micrometers) have been used to infer the vertical variations of Titan's ice abundances, as well as those of the aerosol from the surface to an altitude of 300 km [1]. The aerosol has a broad emission feature centered approximately at 140 per centimeter (71 micrometers). As seen in Figure 1, this feature cannot be reproduced using currently available optical constants from laboratory-generated Titan aerosol analogs [2]. The far-IR is uniquely qualified for investigating low-energy vibrational motions within the lattice structures of COITIDlex aerosol. The feature observed by CIRS is broad, and does not likely arise from individual molecules, but rather is representative of the skeletal movements of macromolecules. Since Cassini's arrival at Titan, benzene (C6H6) has been detected in the atmosphere at ppm levels as well as ions that may be polycyclic aromatic hydrocarbons (PAHs) [3]. We speculate that the feature may be a blended composite that can be identified with low-energy vibrations of two-dimensional lattice structures of large molecules, such as PAHs or nitrogenated aromatics. Such structures do not dominate the composition of analog materials generated from CH4 and N2 irradiation. We are performing studies forming aerosol analog via UV irradiation of aromatic precursors - specifically C6H6 - to understand how the unique chemical architecture of the products will influence the observable aerosol characteristics. The optical and chemical properties of the aromatic analog will be compared to those formed from CH4/N2 mixtures, with a focus on the as-yet unidentified far-IR absorbance feature. Preliminary results indicate that the photochemically-formed aromatic aerosol has distinct chemical composition, and may incorporate nitrogen either into the ring structure or adjoined chemical groups. These compositional differences are

  14. Production Of Titan'S Aerosols Analogues By Radio Frequency Plasma Discharge

    NASA Astrophysics Data System (ADS)

    Szopa, Cyril; Cernogora, G.; Quirico, E.; Bernard, J.; Coll, P.

    2006-09-01

    Titan's organic aerosols play a significant role in the physico-chemical mechanisms of the Titan's atmosphere and heat transfer to the Titan's surface. They also contribute to the physico-chemical properties of the Titan's surface, and more particularly to its reflectance, as they can have accumulated at the surface fro a long period. However, the amount of direct data dealing with the Titan's aerosols is quite low, and the data recovered by the Cassini and Huygens probes remain difficult to interpret without any reference data. This is the reason why we developed a laboratory experiment which simulates the Titan's atmosphere chemistry and produces analogues of Titan's aerosols, with the aim to study the properties of the Titan's aerosols and their way of formation.. In this experiment, the Titan's chemistry is simulated by a low pressure Radio Frequency plasma discharge in a N2-CH4 gas mixture. In this device, aerosols are produced in the gas phase without interaction with the reactor walls. The aim of this paper is to present recent results obtained with this experiment. Chemical composition, physical properties, morphology of the produced particles will be presented, as well as their dependence on the plasma conditions. Moreover, the properties of the plasma characterized by optical and eletrcial diagnostics will also be presented. A correlation of the solids particles properties and the plasma characteristics will be attempted. We will finally attempt to correlate these laboratory results with the known properties of the Titan's aerosols in order to try to bring additional information on the Titan's aerosols properties and their way of formation.

  15. Theoretical Modeling for Hepatic Microwave Ablation

    PubMed Central

    Prakash, Punit

    2010-01-01

    Thermal tissue ablation is an interventional procedure increasingly being used for treatment of diverse medical conditions. Microwave ablation is emerging as an attractive modality for thermal therapy of large soft tissue targets in short periods of time, making it particularly suitable for ablation of hepatic and other tumors. Theoretical models of the ablation process are a powerful tool for predicting the temperature profile in tissue and resultant tissue damage created by ablation devices. These models play an important role in the design and optimization of devices for microwave tissue ablation. Furthermore, they are a useful tool for exploring and planning treatment delivery strategies. This review describes the status of theoretical models developed for microwave tissue ablation. It also reviews current challenges, research trends and progress towards development of accurate models for high temperature microwave tissue ablation. PMID:20309393

  16. Image-Guided Ablation of Adrenal Lesions

    PubMed Central

    Yamakado, Koichiro

    2014-01-01

    Although laparoscopic adrenalectomy has remained the standard of care for the treatment for adrenal tumors, percutaneous image-guided ablation therapy, such as chemical ablation, radiofrequency ablation, cryoablation, and microwave ablation, has been shown to be clinically useful in many nonsurgical candidates. Ablation therapy has been used to treat both functioning adenomas and malignant tumors, including primary adrenal carcinoma and metastasis. For patients with functioning adenomas, biochemical and symptomatic improvement is achieved in 96 to 100% after ablation; for patients with malignant adrenal neoplasms, however, the survival benefit from ablation therapy remains unclear, though good initial results have been reported. This article outlines the current role of ablation therapy for adrenal lesions, as well as identifying some of the technical considerations for this procedure. PMID:25049444

  17. Femtosecond lasers for machining of transparent, brittle materials: ablative vs. non-ablative femtosecond laser processing

    NASA Astrophysics Data System (ADS)

    Hendricks, F.; Matylitsky, V. V.

    2016-03-01

    This paper focuses on precision machining of transparent materials by means of ablative and non-ablative femtosecond laser processing. Ablation technology will be compared with a newly developed patent pending non-ablative femtosecond process, ClearShapeTM, using the Spectra-Physics Spirit industrial femtosecond laser.

  18. Radiative transfer analyses of Titan's tropical atmosphere

    NASA Astrophysics Data System (ADS)

    Griffith, Caitlin A.; Doose, Lyn; Tomasko, Martin G.; Penteado, Paulo F.; See, Charles

    2012-04-01

    Titan's optical and near-IR spectra result primarily from the scattering of sunlight by haze and its absorption by methane. With a column abundance of 92 km amagat (11 times that of Earth), Titan's atmosphere is optically thick and only ˜10% of the incident solar radiation reaches the surface, compared to 57% on Earth. Such a formidable atmosphere obstructs investigations of the moon's lower troposphere and surface, which are highly sensitive to the radiative transfer treatment of methane absorption and haze scattering. The absorption and scattering characteristics of Titan's atmosphere have been constrained by the Huygens Probe Descent Imager/Spectral Radiometer (DISR) experiment for conditions at the probe landing site (Tomasko, M.G., Bézard, B., Doose, L., Engel, S., Karkoschka, E. [2008a]. Planet. Space Sci. 56, 624-247; Tomasko, M.G. et al. [2008b]. Planet. Space Sci. 56, 669-707). Cassini's Visual and Infrared Mapping Spectrometer (VIMS) data indicate that the rest of the atmosphere (except for the polar regions) can be understood with small perturbations in the high haze structure determined at the landing site (Penteado, P.F., Griffith, C.A., Tomasko, M.G., Engel, S., See, C., Doose, L., Baines, K.H., Brown, R.H., Buratti, B.J., Clark, R., Nicholson, P., Sotin, C. [2010]. Icarus 206, 352-365). However the in situ measurements were analyzed with a doubling and adding radiative transfer calculation that differs considerably from the discrete ordinates codes used to interpret remote data from Cassini and ground-based measurements. In addition, the calibration of the VIMS data with respect to the DISR data has not yet been tested. Here, VIMS data of the probe landing site are analyzed with the DISR radiative transfer method and the faster discrete ordinates radiative transfer calculation; both models are consistent (to within 0.3%) and reproduce the scattering and absorption characteristics derived from in situ measurements. Constraints on the atmospheric

  19. Microwave ablation of hepatocellular carcinoma

    PubMed Central

    Poggi, Guido; Tosoratti, Nevio; Montagna, Benedetta; Picchi, Chiara

    2015-01-01

    Although surgical resection is still the optimal treatment option for early-stage hepatocellular carcinoma (HCC) in patients with well compensated cirrhosis, thermal ablation techniques provide a valid non-surgical treatment alternative, thanks to their minimal invasiveness, excellent tolerability and safety profile, proven efficacy in local disease control, virtually unlimited repeatability and cost-effectiveness. Different energy sources are currently employed in clinics as physical agents for percutaneous or intra-surgical thermal ablation of HCC nodules. Among them, radiofrequency (RF) currents are the most used, while microwave ablations (MWA) are becoming increasingly popular. Starting from the 90s’, RF ablation (RFA) rapidly became the standard of care in ablation, especially in the treatment of small HCC nodules; however, RFA exhibits substantial performance limitations in the treatment of large lesions and/or tumors located near major heat sinks. MWA, first introduced in the Far Eastern clinical practice in the 80s’, showing promising results but also severe limitations in the controllability of the emitted field and in the high amount of power employed for the ablation of large tumors, resulting in a poor coagulative performance and a relatively high complication rate, nowadays shows better results both in terms of treatment controllability and of overall coagulative performance, thanks to the improvement of technology. In this review we provide an extensive and detailed overview of the key physical and technical aspects of MWA and of the currently available systems, and we want to discuss the most relevant published data on MWA treatments of HCC nodules in regard to clinical results and to the type and rate of complications, both in absolute terms and in comparison with RFA. PMID:26557950

  20. Microwave ablation of hepatocellular carcinoma.

    PubMed

    Poggi, Guido; Tosoratti, Nevio; Montagna, Benedetta; Picchi, Chiara

    2015-11-01

    Although surgical resection is still the optimal treatment option for early-stage hepatocellular carcinoma (HCC) in patients with well compensated cirrhosis, thermal ablation techniques provide a valid non-surgical treatment alternative, thanks to their minimal invasiveness, excellent tolerability and safety profile, proven efficacy in local disease control, virtually unlimited repeatability and cost-effectiveness. Different energy sources are currently employed in clinics as physical agents for percutaneous or intra-surgical thermal ablation of HCC nodules. Among them, radiofrequency (RF) currents are the most used, while microwave ablations (MWA) are becoming increasingly popular. Starting from the 90s', RF ablation (RFA) rapidly became the standard of care in ablation, especially in the treatment of small HCC nodules; however, RFA exhibits substantial performance limitations in the treatment of large lesions and/or tumors located near major heat sinks. MWA, first introduced in the Far Eastern clinical practice in the 80s', showing promising results but also severe limitations in the controllability of the emitted field and in the high amount of power employed for the ablation of large tumors, resulting in a poor coagulative performance and a relatively high complication rate, nowadays shows better results both in terms of treatment controllability and of overall coagulative performance, thanks to the improvement of technology. In this review we provide an extensive and detailed overview of the key physical and technical aspects of MWA and of the currently available systems, and we want to discuss the most relevant published data on MWA treatments of HCC nodules in regard to clinical results and to the type and rate of complications, both in absolute terms and in comparison with RFA. PMID:26557950

  1. The interaction of benzene and ethylene under Titan surface conditions

    NASA Astrophysics Data System (ADS)

    Beauchamp, Patricia; Vu, Tuan H.; Cable, Morgan L.; Hodyss, Robert P.; Choukroun, Mathieu

    2014-11-01

    Previously, we have reported the discovery and characterization of a new co-crystal formed from benzene and ethane (Vu et al. 2014 J. Phys Chem. A 118, 4087; Cable et al. 2014 GRL 41, doi:10.1002/2014GL060531). This co-crystal would be thermodynamically stable on Titan’s surface, and forms easily from the interaction of liquid ethane and solid benzene, as well as from the evaporation of benzene saturated solutions of ethane. These results imply that the benzene-ethane co-crystal may be an important component of Titan’s evaporate deposits. The formation of these kinds of organic co-crystals may influence evaporite characteristics, such as particle size and infrared spectral properties.Here, we report our most recent experiments exploring the interaction between benzene and ethylene. Ethylene has been detected in Titan’s atmosphere, and some photochemical models predict a significant flux to the surface. We performed experiments examining the interaction of liquid ethylene with solid benzene under Titan-like conditions (90-150 K and 1 bar N2), using micro-Raman spectroscopy and optical microscopy. We will present Raman spectra and vibrational analyses of the interaction, and implications for Titan’s surface chemistry and evolution.This work has been conducted at the Jet Propulsion Laboratory, California Institute of Technology, under contract to NASA. Copyright 2014, California Institute of Technology. Support by the NASA Astrobiology Institute (Titan as a Prebiotic Chemical System), the NASA Outer Planets Research Program and government sponsorship are gratefully acknowledged.

  2. A Search for Minor Constituents on Titan and Jupiter

    NASA Astrophysics Data System (ADS)

    Kostiuk, Theodor; Livengood, T. A.; Fast, K.; Hewagama, T.; Buhl, D.; Delgado, J.; Smith, R.; Blass, W.

    2008-09-01

    Spectroscopy at resolving power R 1,000,000 of ethane (C2H6) lines in emission on Titan in the study of global winds, and Jupiter in the study of mid-infrared aurora, reveals spectral features that can not be identified using available ethane line atlases. Unidentified ethane lines or lines corresponding to other species overlapping the 12.2 μm ν9 ethane band may be present. Hydrocarbon species resulting from methane chemistry in these atmospheres such as, allene (C3H4), ethylene (C2H4), and propane (C3H8), all have bands overlapping this spectral region. The high resolving power of infrared heterodyne spectroscopy measurements resolves the overlapping spectral lines and permits identification of the parent molecules. Measurements with the NASA GSFC Heterodyne Instrument for Planetary Wind And Composition (HIPWAC) on the NASA IRTF and on the National Astronomical Observatory of Japan Subaru Telescope are analyzed for retrieval of spectral evidence for the presence of these candidate molecules. Laboratory spectral measurements of the candidate molecules at equal spectral resolution are used to help identify the spectral features in the remote data. Results of this study will be discussed as well as their implications for the retrieval of ethane and hydrocarbon abundances in the stratospheres of Titan, Jupiter and the outer planets. This work was supported by the NASA Planetary Astronomy Program and is based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan, and data collected on the NASA Infrared Telescope Facility.

  3. Transhemangioma Ablation of Hepatocellular Carcinoma

    SciTech Connect

    Pua, Uei

    2012-12-15

    Radiofrequency ablation (RFA) is a well-established treatment modality in the treatment of early hepatocellular carcinoma (HCC) [1]. Safe trajectory of the RFA probe is crucial in decreasing collateral tissue damage and unwarranted probe transgression. As a percutaneous technique, however, the trajectory of the needle is sometimes constrained by the available imaging plane. The presence of a hemangioma beside an HCC is uncommon but poses the question of safety related to probe transgression. We hereby describe a case of transhemangioma ablation of a dome HCC.

  4. Photochemical ablation of organic solids

    NASA Astrophysics Data System (ADS)

    Yingling, Yaroslava G.; Garrison, Barbara J.

    2003-04-01

    We have investigated by molecular dynamics simulations the ablation of material that is onset by photochemical processes. We compare this system with only photochemical processes to a system containing photochemical and photothermal processes. The simulations reveal that ablation by purely photochemical processes is accompanied by the ejection of relatively cold massive molecular clusters from the surface of the sample. The top of the plume exhibits high temperatures whereas the residual part of the sample is cold. The removal of the damaged material through big molecular cluster ejection is consistent with experimental observations of low heat damage of material.

  5. Laser ablation based fuel ignition

    DOEpatents

    Early, J.W.; Lester, C.S.

    1998-06-23

    There is provided a method of fuel/oxidizer ignition comprising: (a) application of laser light to a material surface which is absorptive to the laser radiation; (b) heating of the material surface with the laser light to produce a high temperature ablation plume which emanates from the heated surface as an intensely hot cloud of vaporized surface material; and (c) contacting the fuel/oxidizer mixture with the hot ablation cloud at or near the surface of the material in order to heat the fuel to a temperature sufficient to initiate fuel ignition. 3 figs.

  6. Laser ablation based fuel ignition

    DOEpatents

    Early, James W.; Lester, Charles S.

    1998-01-01

    There is provided a method of fuel/oxidizer ignition comprising: (a) application of laser light to a material surface which is absorptive to the laser radiation; (b) heating of the material surface with the laser light to produce a high temperature ablation plume which emanates from the heated surface as an intensely hot cloud of vaporized surface material; and (c) contacting the fuel/oxidizer mixture with the hot ablation cloud at or near the surface of the material in order to heat the fuel to a temperature sufficient to initiate fuel ignition.

  7. Atrial Fibrillation Ablation and Stroke.

    PubMed

    Aagaard, Philip; Briceno, David; Csanadi, Zoltan; Mohanty, Sanghamitra; Gianni, Carola; Trivedi, Chintan; Nagy-Baló, Edina; Danik, Stephan; Barrett, Conor; Santoro, Francesco; Burkhardt, J David; Sanchez, Javier; Natale, Andrea; Di Biase, Luigi

    2016-05-01

    Catheter ablation has become a widely available and accepted treatment to restore sinus rhythm in atrial fibrillation patients who fail antiarrhythmic drug therapy. Although generally safe, the procedure carries a non-negligible risk of complications, including periprocedural cerebral insults. Uninterrupted anticoagulation, maintenance of an adequate ACT during the procedure, and measures to avoid and detect thrombus build-up on sheaths and atheters during the procedure, appears useful to reduce the risk of embolic events. This is a review of the incidence, mechanisms, impact, and methods to reduce catheter ablation related cerebral insults. PMID:27150179

  8. Radiofrequency ablation of lung tumours

    PubMed Central

    Goh, PYT

    2006-01-01

    Radiofrequency ablation (RFA) is a well-established local therapy for hepatic malignancies. It is rapidly emerging as an effective treatment modality for small lesions elsewhere in the body, in particular, the kidney and the lung. It is a relatively safe and minimally invasive treatment for small lung malignancies, both primary and secondary. In particular, it is the preferred form of treatment for non-surgical candidates. This paper describes the technique employed for radiofrequency ablation of lung tumours, as well as the protocol established, at the Mount Elizabeth Hospital, Singapore. PMID:21614247

  9. Ablative Therapies for Barrett's Esophagus

    PubMed Central

    Garman, Katherine S.; Shaheen, Nicholas J.

    2011-01-01

    Barrett's esophagus has gained increased clinical attention because of its association with esophageal adenocarcinoma, a cancer with increasing incidence and poor survival rates. The goals of ablating Barrett's esophagus are to decrease esophageal cancer rates and to improve overall survival and quality of life. Different techniques have been developed and tested for their effectiveness eradicating Barrett's epithelium. This review assesses the literature associated with different ablative techniques. The safety and efficacy of different techniques are discussed. This review concludes with recommendations for the clinician, including specific strategies for patient care decisions for patients with Barrett's esophagus with varying degrees of dysplasia. PMID:21373836

  10. Tektite ablation - Some confirming calculations.

    NASA Technical Reports Server (NTRS)

    O'Keefe, J. A., III; Silver, A. D.; Cameron, W. S.; Adams , E. W.; Warmbrod, J. D.

    1973-01-01

    The calculation of tektite ablation has been redone, taking into account transient effects, internal radiation, melting and nonequilibrium vaporization of the glass, and the drag effect of the flanges. It is found that the results confirm the earlier calculations of Chapman and his group and of Adams and his co-workers. The general trend of the results is not sensitive to reasonable changes of the physical parameters. The ablation is predominantly by melting rather than by vaporization at all velocities up to 11 km/sec; this is surprising in view of the lack of detectable melt flow in most tektites. Chemical effects have not been considered.

  11. Catheter ablation of parahisian premature ventricular complex.

    PubMed

    Kim, Jun; Kim, Jeong Su; Park, Yong Hyun; Kim, June Hong; Chun, Kook Jin

    2011-12-01

    Catheter ablation is performed in selected patients with a symptomatic premature ventricular complex (PVC) or PVC-induced cardiomyopathy. Ablation of PVC from the His region has a high risk of inducing a complete atrioventricular block. Here we report successful catheter ablation of a parahisian PVC in a 63-year-old man.

  12. Cassini sheds light on Titan's second largest lake, Ligeia Mare

    NASA Astrophysics Data System (ADS)

    Wendel, JoAnna

    2014-04-01

    Saturn's largest moon, Titan, is known for its dense, planet-like atmosphere and large lakes most likely made of methane and ethane. It has been suggested that Titan's atmosphere and surface are a model of early Earth. Since the early 2000s, NASA's Cassini space probe has been unlocking secrets of the distant moon.

  13. Determining the induced and intrinsic fields of Titan

    NASA Astrophysics Data System (ADS)

    Wei, H.; Ma, Y.; Russell, C. T.; Dougherty, M. K.

    2014-12-01

    Cassini mission has obtained abundant measurements around Titan and along its orbit, allowing us to better understand Titan's plasma interaction with its environment and estimate the induced and intrinsic fields from Titan's interior. The magnetic state of Titan could provide important constraints on its interior structures. The presence of an induced field indicates that there are conductive layer/layers in the interior, while the presence and strength of a dynamo-driven intrinsic field provide information on the dynamics in the interior and the thermal state of the material deep inside. When estimating the induced and intrinsic fields of Titan, the most important technique and biggest difficulty is to separate the field generated by the interaction between Titan's ionosphere and its plasma environment from that generated from Titan's interior. Therefore we use MHD simulations to predict the fields from external and internal sources. By comparing observations with simulations, we can search for the signatures of the induced field of Titan and improve the accuracy of our previous intrinsic field estimates.

  14. The low temperature organic chemistry of Titan's geofluid.

    PubMed

    Raulin, F; Bruston, P; Paillous, P; Sternberg, R

    1995-03-01

    Organic chemistry on Titan and prebiotic chemistry on Earth involve the same N-containing organics: nitriles and their oligomers. Couplings of their chemistry in the three parts of Titan's geofluid (atmosphere, aerosols and surface) seem to play a key role in the organic chemical evolution of the planet. If liquid water was present on Titan, then a prebiotic chemistry, involving eutectics, similar to that of the early Earth, may have occurred. However, liquid water is currently absent and a prebiotic chemistry based only on N-organics may be evolving now on Titan. The other consequence of the low temperatures of Titan is the possible formation of organics unstable at room temperature and very reactive. So far, these compounds have not been systematically searched for in experimental studies of Titan's organic chemistry. C4N2 has already been detected on Titan. Powerful reactants in organic chemistry, CH2N2, and CH3N3, may be also present. They exhibit spectral signatures in the mid-IR strong enough to allow their detection at the 10-100 ppb level. They may be detectable on future IR spectra (ISO and Cassini) of Titan.

  15. Effects of Saturn's magnetospheric dynamics on Titan's ionosphere

    NASA Astrophysics Data System (ADS)

    Edberg, N. J. T.; Andrews, D. J.; Bertucci, C.; Gurnett, D. A.; Holmberg, M. K. G.; Jackman, C. M.; Kurth, W. S.; Menietti, J. D.; Opgenoorth, H. J.; Shebanits, O.; Vigren, E.; Wahlund, J.-E.

    2015-10-01

    We use the Cassini Radio and Plasma Wave Science/Langmuir probe measurements of the electron density from the first 110 flybys of Titan to study how Saturn's magnetosphere influences Titan's ionosphere. The data is first corrected for biased sampling due to varying solar zenith angle and solar energy flux (solar cycle effects). We then present results showing that the electron density in Titan's ionosphere, in the altitude range 1600-2400 km, is increased by about a factor of 2.5 when Titan is located on the nightside of Saturn (Saturn local time (SLT) 21-03 h) compared to when on the dayside (SLT 09-15 h). For lower altitudes (1100-1600 km) the main dividing factor for the ionospheric density is the ambient magnetospheric conditions. When Titan is located in the magnetospheric current sheet, the electron density in Titan's ionosphere is about a factor of 1.4 higher compared to when Titan is located in the magnetospheric lobes. The factor of 1.4 increase in between sheet and lobe flybys is interpreted as an effect of increased particle impact ionization from ˜200 eV sheet electrons. The factor of 2.5 increase in electron density between flybys on Saturn's nightside and dayside is suggested to be an effect of the pressure balance between thermal plus magnetic pressure in Titan's ionosphere against the dynamic pressure and energetic particle pressure in Saturn's magnetosphere.

  16. Radiation stability of sodium titanate ion exchange materials

    SciTech Connect

    Kenna, B.T.

    1980-02-01

    Sodium titanate and sodium titanate loaded macroreticular resin are being considered as ion exchangers to remove /sup 90/Sr and actinides from the large volume of defense waste stored at Hanford Site in Washington. Preliminary studies to determine the radiation effect on Sr/sup +2/ and I/sup -/ capacity of these ion-exchange materials were conducted. Samples of sodium titanate powder, sodium titanate loaded macroreticular resin, as well as the nitrate form of macroreticular anion resin were irradiated with up to 2 x 10/sup 9/ Rads of /sup 60/Co gamma rays. Sodium titanate cation capacity decreased about 50% while the sodium titanate loaded macroeticular resin displayed a dramatic decrease in cation capacity when irradiated with 10/sup 8/-10/sup 9/ Rad. The latter decrease is tentatively ascribed to radiation damage to the organic portion which subsequently inhibits interaction with the contained sodium titanate. The anion capacity of both macroreticular resin and sodium titanate loaded macroreticular resin exhibited significant decreases with increasing radiation exposure. These results suggest that consideration should be given to the potential effects of radiation degradation if column regeneration is to be used. 5 figures, 2 tables.

  17. An improved automotive brake lining using fibrous potassium titanate

    NASA Technical Reports Server (NTRS)

    Mansfield, J. A.; Halberstadt, M. L.; Riccitiello, S. R.; Rhee, S. K.

    1976-01-01

    Simultaneous fade reduction and wear improvement of a commercial automotive brake lining were achieved by adding fibrous potassium titanate. The dependence of friction and wear characteristics on quantitative variations in potassium titanate, asbestos, phenolic binder, and organic and inorganic modifiers was evaluated.

  18. Conditional Lineage Ablation to Model Human Diseases

    NASA Astrophysics Data System (ADS)

    Lee, Paul; Morley, Gregory; Huang, Qian; Fischer, Avi; Seiler, Stephanie; Horner, James W.; Factor, Stephen; Vaidya, Dhananjay; Jalife, Jose; Fishman, Glenn I.

    1998-09-01

    Cell loss contributes to the pathogenesis of many inherited and acquired human diseases. We have developed a system to conditionally ablate cells of any lineage and developmental stage in the mouse by regulated expression of the diphtheria toxin A (DTA) gene by using tetracycline-responsive promoters. As an example of this approach, we targeted expression of DTA to the hearts of adult mice to model structural abnormalities commonly observed in human cardiomyopathies. Induction of DTA expression resulted in cell loss, fibrosis, and chamber dilatation. As in many human cardiomyopathies, transgenic mice developed spontaneous arrhythmias in vivo, and programmed electrical stimulation of isolated-perfused transgenic hearts demonstrated a strikingly high incidence of spontaneous and inducible ventricular tachycardia. Affected mice showed marked perturbations of cardiac gap junction channel expression and localization, including a subset with disorganized epicardial activation patterns as revealed by optical action potential mapping. These studies provide important insights into mechanisms of arrhythmogenesis and suggest that conditional lineage ablation may have wide applicability for studies of disease pathogenesis.

  19. The Huygens Gas Chromatograph Mass Spectrometer Investigation Of Titan

    NASA Astrophysics Data System (ADS)

    Atreya, Sushil; Harpold, Dan; Owen, Tobias

    2015-04-01

    A decade ago, on 14 January 2005, the Huygens probe of the Cassini-Huygens mission descended through the smog filled atmosphere of Titan and landed on the surface, revealing for the first time the extraordinary nature of Saturn's largest moon. One of the six payload instruments, the gas chromatograph mass spectrometer (GCMS), was crucial for measuring the composition of the atmosphere and the surface of Titan [1,2]. Most of the GCMS findings were "firsts", including the first direct identification of molecular nitrogen as the bulk constituent of the atmosphere, first vertical profile of Titan's second most abundant volatile, methane, first determination of primordial and radiogenic argon, first quantification of a number of stable gas isotopes, and the first measurements of the make-up of Titan's surface. These data are key to understanding why Titan is so unique amongst planetary moons in possessing a massive atmosphere [3], how Titan maintains a cycle of methane complete with surface reservoirs, evaporation and condensation like the hydrological cycle on earth [3,4,5], and what is responsible for the photochemical smog on Titan that plays a central role in the very existence of an atmosphere on Titan [3]. This presentation will discuss the GCMS investigation and how it helped shape our current view of Titan. [website for downloading pdf's of relevant papers: www.umich.edu/~atreya] [1] Niemann, H. B. et al., The abundances of constituents of Titan's atmosphere from the GCMS instrument on the Huygens probe, Nature 438, 779-784, 2005. [2] Niemann, H. B. et al., The composition of Titan's lower atmosphere and simple surface volatiles as measured by the Cassini-Huygens probe gas chromatograph mass spectrometer experiment, J. Geophys. Res. (Planets) 115, 12006, 2010. [3] Atreya S. K., R. D. Lorenz and J. H. Waite, Volatile origin and cycles: Nitrogen and methane, in Titan from Cassini-Huygens, R. H. Brown, J. P. Lebreton and J. Waite, (eds.), Springer Dordrecht

  20. The 8-13 micron observations of Titan. [temperature inversion in Titan atmosphere

    NASA Technical Reports Server (NTRS)

    Gillett, F. C.; Forrest, W. J.; Merrill, K. M.

    1974-01-01

    Narrow band observations of Titan at selected wavelengths in the 8-13 micron range show evidence for a strong temperature inversion and the existence of at least one more spectroscopically active component in the atmosphere in addition to H2 and CH4.

  1. Titan's atmosphere and surface in 2026: the AVIATR Titan Airplane Mission

    NASA Astrophysics Data System (ADS)

    McKay, Chris; Barnes, Jason W.; Lemke, Lawrence; Beyer, Ross A.; Radebaugh, Jani; Atkinson, David; Flasar, F. Michael

    2010-04-01

    This poster describes the scientific, engineering, and operations planning for a Discovery / New Frontiers class Titan airplane mission, AVIATR (Aerial Vehicle for In-situ and Airborne Titan Reconnaissance). The mission would focus on Titan's surface and atmospheric diversity, using high-resolution imaging, near-infrared spectroscopy, a haze spectrometer, and atmospheric structure measurements. Previous mission studies have elected to use hot-air balloons to achieve similar science goals. These hot-air balloon concepts require the waste heat from inefficient thermocouple-based Radioisotope Thermoelectric Generators (RTGs) for buoyancy. New Advanced Stirling Radioisotope Generators (ASRGs) are much more efficient than RTGs both in terms of power produced per gram of plutonium-238 and the total watts-per-kilogram of the power unit itself. However, they are so efficient that they are much less effective for use in heating a hot-air balloon. Similarly, old-style RTGs produce insufficient specific power for heavier-than-air flight, but the use of 2 ASRGs can support a 120 kg airplane for a long-duration mission at Titan. The AVIATR airplane concept has several advantages in its science capabilities relative to a balloon, including the ability to target any site of interest, remaining on the dayside, stereo and repeat coverage, and easy altitude changes. It also possesses engineering advantages over a balloon like low total mass, a more straightforward deployment sequence, direct-to-Earth communications capability, and a more robust airframe.

  2. HCN ice in Titan's high-altitude southern polar cloud.

    PubMed

    de Kok, Remco J; Teanby, Nicholas A; Maltagliati, Luca; Irwin, Patrick G J; Vinatier, Sandrine

    2014-10-01

    Titan's middle atmosphere is currently experiencing a rapid change of season after northern spring arrived in 2009 (refs 1, 2). A large cloud was observed for the first time above Titan's southern pole in May 2012, at an altitude of 300 kilometres. A temperature maximum was previously observed there, and condensation was not expected for any of Titan's atmospheric gases. Here we report that this cloud is composed of micrometre-sized particles of frozen hydrogen cyanide (HCN ice). The presence of HCN particles at this altitude, together with temperature determinations from mid-infrared observations, indicate a dramatic cooling of Titan's atmosphere inside the winter polar vortex in early 2012. Such cooling is in contrast to previously measured high-altitude warming in the polar vortex, and temperatures are a hundred degrees colder than predicted by circulation models. These results show that post-equinox cooling at the winter pole of Titan is much more efficient than previously thought. PMID:25279918

  3. TALISE: Titan Lake In-situ Sampling Propelled Explorer

    NASA Astrophysics Data System (ADS)

    Urdampilleta, I.; Prieto-Ballesteros, O.; Rebolo, R.; Sancho, J.

    2012-09-01

    Titan is the largest satellite of Saturn System, the only one in the Solar System with a significant atmosphere. About 95% is nitrogen, approximately 3% is methane, and the remaining 2% percent consists of hydrogen, little vapour water, other hydrocarbons, and possibly argon. Hydrocarbons may rain down on the surface, forming enclosed seas, lakes, and ponds. Radar images obtained appear to show lakes of liquid hydrocarbon (such as methane and ethane) in Titan's northern latitudes. The chemical composition of the lakes of Titan is still not well determined. The detection of other compounds and the investigation of influence of both, photochemistry and the atmosphere on the chemical composition of liquids of Titan lakes remain challenging in the absence of in situ measurements. Therefore, it is next step to understand the Titan lakes environment, its relationship with the climate behavior, the surrounding solid substrate and analyze the organic inventory including the possibility of prebiotic compounds.

  4. Charged particle tracking at Titan, and further applications

    NASA Astrophysics Data System (ADS)

    Bebesi, Zsofia; Erdos, Geza; Szego, Karoly

    2016-04-01

    We use the CAPS ion data of Cassini to investigate the dynamics and origin of Titan's atmospheric ions. We developed a 4th order Runge-Kutta method to calculate particle trajectories in a time reversed scenario. The test particle magnetic field environment imitates the curved magnetic environment in the vicinity of Titan. The minimum variance directions along the S/C trajectory have been calculated for all available Titan flybys, and we assumed a homogeneous field that is perpendicular to the minimum variance direction. Using this method the magnetic field lines have been calculated along the flyby orbits so we could select those observational intervals when Cassini and the upper atmosphere of Titan were magnetically connected. We have also taken the Kronian magnetodisc into consideration, and used different upstream magnetic field approximations depending on whether Titan was located inside of the magnetodisc current sheet, or in the lobe regions. We also discuss the code's applicability to comets.

  5. Energetic neutral atom emissions from Titan interaction with Saturn's magnetosphere.

    PubMed

    Mitchell, D G; Brandt, P C; Roelof, E C; Dandouras, J; Krimigis, S M; Mauk, B H

    2005-05-13

    The Cassini Magnetospheric Imaging Instrument (MIMI) observed the interaction of Saturn's largest moon, Titan, with Saturn's magnetosphere during two close flybys of Titan on 26 October and 13 December 2004. The MIMI Ion and Neutral Camera (INCA) continuously imaged the energetic neutral atoms (ENAs) generated by charge exchange reactions between the energetic, singly ionized trapped magnetospheric ions and the outer atmosphere, or exosphere, of Titan. The images reveal a halo of variable ENA emission about Titan's nearly collisionless outer atmosphere that fades at larger distances as the exospheric density decays exponentially. The altitude of the emissions varies, and they are not symmetrical about the moon, reflecting the complexity of the interactions between Titan's upper atmosphere and Saturn's space environment.

  6. The Properties and Effects of Titan's Organic Haze

    NASA Technical Reports Server (NTRS)

    McKay, Christopher P.; Young, Richard E. (Technical Monitor)

    1997-01-01

    Titan's organic haze is the the dominant absorber of solar energy in Titan's atmosphere, creating an anti-greenhouse effect. Its variation over time may have had important implications for Titan's surface temperature. The haze is potentially an important sink of photochemically produced carbon and nitrogen compounds. Laboratory simulations and microphysical models suggest that the haze is a sink for C of 4 x 10(exp 8)/ sq cm s, and a sink for N of 1 x 10(exp 8)sq cm s. The C sink is small compared to condensation of hydrocarbons but the sink for N is comparable to the total production rate of HCN. Because estimates of the eddy diffusion profile on Titan have been based on the HCN profile, inclusion of this additional sink for N will affect estimates for all transport processes in Titan's atmosphere.

  7. Fluvial transport on Titan: formation and evolution of river deltas

    NASA Astrophysics Data System (ADS)

    Witek, Piotr Przemyslaw; Czechowski, Leszek

    2016-10-01

    The Cassini-Huygens mission provided numerous observations indicating that processes of sediment transport are currently operating on the surface of Titan. We performed numerical simulations of flow and sediment transport on Titan with particular emphasis on formation of sedimentary landforms in Titan's lakes. We compared the morphology and evolution of landforms formed in Titanian and terrestrial conditions, under various discharges and with different dominant grain sizes. The processes are similar in both environments; in some cases we observed bifurcation of the flow and switching of the active distributaries. Such processes may lead to abandonment of some delta lobes, as hypothesized for the delta observed in Ontario Lacus on Titan. The lower gravity of Titan and higher buoyancy of the most plausible kinds of sediment result in higher efficiency of transport and generally faster evolution of the deltaic deposits. Our results suggest also that the flat, lobate river deltas may form in narrower range of parameters than on Earth.

  8. Simulating Titan's methane cycle with the TitanWRF General Circulation Model

    NASA Astrophysics Data System (ADS)

    Newman, Claire E.; Richardson, Mark I.; Lian, Yuan; Lee, Christopher

    2016-03-01

    Observations provide increasing evidence of a methane hydrological cycle on Titan. Earth-based and Cassini-based monitoring has produced data on the seasonal variation in cloud activity and location, with clouds being observed at increasingly low latitudes as Titan moved out of southern summer. Lakes are observed at high latitudes, with far larger lakes and greater areal coverage in the northern hemisphere, where some shorelines extend down as far as 50°N. Rainfall at some point in the past is suggested by the pattern of flow features on the surface at the Huygens landing site, while recent rainfall is suggested by surface change. As with the water cycle on Earth, the methane cycle on Titan is both impacted by tropospheric dynamics and likely able to impact this circulation via feedbacks. Here we use the 3D TitanWRF General Circulation Model (GCM) to simulate Titan's methane cycle. In this initial work we use a simple large-scale condensation scheme with latent heat feedbacks and a finite surface reservoir of methane, and focus on large-scale dynamical interactions between the atmospheric circulation and methane, and how these impact seasonal changes and the long term (steady state) behavior of the methane cycle. We note five major conclusions: (1) Condensation and precipitation in the model is sporadic in nature, with interannual variability in its timing and location, but tends to occur in association with both (a) frequent strong polar upwelling during spring and summer in each hemisphere, and (b) the Inter-Tropical Convergence Zone (ITCZ), a region of increased convergence and upwelling due to the seasonally shifting Hadley cells. (2) An active tropospheric methane cycle affects the stratospheric circulation, slightly weakening the stratospheric superrotation produced. (3) Latent heating feedback strongly influences surface and near-surface temperatures, narrowing the latitudinal range of the ITCZ, and changing the distribution - and generally weakening the

  9. Feasibility evaluation of the monolithic braided ablative nozzle

    NASA Astrophysics Data System (ADS)

    Director, Mark N.; McPherson, Douglass J., Sr.

    1992-02-01

    The feasibility of the monolithic braided ablative nozzle was evaluated as part of an independent research and development (IR&D) program complementary to the National Aeronautics and Space Administration/Marshall Space Flight Center (NASA/MSFC) Low-Cost, High-Reliability Case, Insulation and Nozzle for Large Solid Rocket Motors (LOCCIN) Program. The monolithic braided ablative nozzle is a new concept that utilizes a continuous, ablative, monolithic flame surface that extends from the nozzle entrance, through the throat, to the exit plane. The flame surface is fabricated using a Through-the-Thickness braided carbon-fiber preform, which is impregnated with a phenolic or phenolic-like resin. During operation, the braided-carbon fiber/resin material ablates, leaving the structural backside at temperatures which are sufficiently low to preclude the need for any additional insulative materials. The monolithic braided nozzle derives its potential for low life cycle cost through the use of automated processing, one-component fabrication, low material scrap, low process scrap, inexpensive raw materials, and simplified case attachment. It also has the potential for high reliability because its construction prevents delamination, has no nozzle bondlines or leak paths along the flame surface, is amenable to simplified analysis, and is readily inspectable. In addition, the braided construction has inherent toughness and is damage-tolerant. Two static-firing tests were conducted using subscale, 1.8 - 2.0-inch throat diameter, hardware. Tests were approximately 15 seconds in duration, using a conventional 18 percent aluminum/ammonium perchlorate propellant. The first of these tests evaluated the braided ablative as an integral backside insulator and exit cone; the second test evaluated the monolithic braided ablative as an integral entrance/throat/exit cone nozzle. Both tests met their objectives. Radial ablation rates at the throat were as predicted, approximately 0.017 in

  10. Production of Titan's aerosols analogues by radio frequency plasma discharge

    NASA Astrophysics Data System (ADS)

    Szopa, C.; Cernogora, G.; Boufendi, L.; Cavarroc, M.; Quirico, E.; Bernard, J. M.; Coll, P.; Jolly, A.

    Titan s organic aerosols play a significant role in the physico-chemical mechanisms of the Titan s atmosphere and heat transfer to the Titan s surface They also contribute to the physico-chemical properties of the Titan s surface and more particularly to its reflectance as they can have accumulated at the surface fro a long period However the amount of direct data dealing with the Titan s aerosols is quite low and the data recovered by the Cassini and Huygens probes remain difficult to interpret without any reference data This is the reason why we developed a laboratory experiment which simulates the Titan s atmosphere chemistry and produces analogues of Titan s aerosols with the aim to study the properties of the Titan s aerosols and their way of formation In this experiment the Titan s chemistry is simulated by a low pressure Radio Frequency plasma discharge in a N2-CH4 gas mixture In this device aerosols are produced in the gas phase without interaction with the reactor walls The aim of this paper is to present recent results obtained with this experiment Chemical composition physical properties morphology of the produced particles will be presented as well as their dependence on the plasma conditions Moreover the properties of the plasma characterized by optical and eletrcial diagnostics will also be presented A correlation of the solids particles properties and the plasma characteristics will be attempted We will finally attempt to correlate these laboratory results with the known properties of the Titan s aerosols in order to try to bring

  11. The First Year of Cassini RADAR Observations of Titan

    NASA Astrophysics Data System (ADS)

    Elachi, C.; Lorenz, R. D.

    2005-12-01

    Titan`s atmosphere is essentially transparent to Radar, making it an ideal technique to study Titan`s surface. Cassini`s Titan Radar Mapper operates as a passive radiometer, scatterometer, altimeter, and synthetic aperture radar (SAR). Here we review data from four fly-bys in the first year of Cassini`s tour (Ta: October 2004, T3: February 2005, T7: September 2005, and T8: October 2005.) Early SAR images from Ta and T3 (showing < 3% of Titan`s surface) reveal that Titan is geologically young and complex (see Elachi et al., 2005, Science 13, 970-4). Significant variations were seen between the range of features seen in the Ta swath (centered at ~50N, 80W) and T3 (~ 30N, 70W) : the large-scale radiometric properties also differed, with T3 being radar-brighter. A variety of features have been identified in SAR, including two large impact craters, cryovolcanic flows and a probable volcanic dome. Dendritic and braided radar-bright sinuous channels, some 180km long, are evidence of fluvial activity. `Cat scratches`, arrays of linear dark features seem most likely to be Aeolian. Radar provides unique topographic information on Titan`s landscape e.g. the depth of the 80km crater observed in T3 can be geometrically determined to be around 1300m deep. Despite the shallow large-scale slopes indicated in altimetry to date, many small hills are seen in T3. Scatterometry and radiometry maps provide large-scale classification of surface types and polarization and incidence angle coverage being assembled will constrain dielectric and scattering properties of the surface. Judging from the TA/T3 diversity, we expect further variations in the types and distribution of surface materials and geologic features in T7, which spans a wide range of Southern latitudes. T8 SAR will cover a near-equatorial dark region, including the landing site of the Huygens probe.

  12. Modern Advances in Ablative TPS

    NASA Technical Reports Server (NTRS)

    Venkatapathy, Ethiraj

    2013-01-01

    Topics covered include: Physics of Hypersonic Flow and TPS Considerations. Destinations, Missions and Requirements. State of the Art Thermal Protection Systems Capabilities. Modern Advances in Ablative TPS. Entry Systems Concepts. Flexible TPS for Hypersonic Inflatable Aerodynamic Decelerators. Conformal TPS for Rigid Aeroshell. 3-D Woven TPS for Extreme Entry Environment. Multi-functional Carbon Fabric for Mechanically Deployable.

  13. Reconstruction of an ablated breast.

    PubMed

    Scarfì, A; Ordemann, K; Hüter, J

    1986-01-01

    It is the aim of the reconstruction of an ablated breast to repair the woman's integrity. The technique of this operation, according to Bomert, is the sliding of a flap of skin in the case of a horizontal breast scar. For the reconstruction, a silicone prosthesis is implanted which in most cases is prepectoral.

  14. Titan Explorer: The Next Step in the Exploration of a Mysterious World

    NASA Technical Reports Server (NTRS)

    Levine, Joel S.; Wright, Henry S.

    2005-01-01

    The Titan Explorer Mission outlined in this report is a proposed next step in the exploration of Titan, following the highly successful Huygens Titan probe of 2005. The proposed Titan Explorer Mission consists of an Orbiter and an Airship that traverses the atmosphere of Titan and can land on its surface. The Titan Explorer Mission is science driven and addresses some of the fundamental questions about the atmosphere, surface and evolution of Titan, which will add to our understanding of the origin and evolution of life on Earth and assess the likelihood of life elsewhere in the Solar System.

  15. Seasonal Changes in Titan's Surface Temperatures

    NASA Technical Reports Server (NTRS)

    Jennings, Donald E.; Nixon, Conor A.; Cottini, Valeria

    2011-01-01

    Cassini's extended mission has provided the opportunity to search for seasonal variations on Titan. In particular, surface temperatures are expected to have shifted significantly in latitude during the completed portion of the mission. Spectra recorded by the Composite Infrared Spectrometer (CIRS) during the nominal mission (2004-08) and the Equinox mission. (2008-10) have already shown changes in temperature. CIRS has detected a seasonal shift in the latitudinal distribution of surface brightness temperatures by comparing zonal averages from two time segments, one period in late northern winter centered on L(sub s) approximately 335 deg and a second period centered on the equinox (L(sub s) approximately 0 deg.). The earlier period had a meridional distribution similar to that previously reported: 93.5 K at the equator, 91.7 K at 85 S and 899 K at 85 N. The newly measured distribution near equinox shows a cooling in the south and a warming in the north, both by about 0.5 K. We estimate that. the centroid of the distribution moved from approximately 16 S to 7 S between the two periods. This gives a seasonal lag behind insolation of delta L(sub s) approximately 13 deg. The CIRS equinox results are consistent with those of Voyager IRIS, which encountered Titan in November 1980, just following the previous northern equinox (L(sub s) = 10 deg.). When compared with predictions from general circulation models, seasonal variations of surface temperature can help constrain the identification of surface materials. Our measurements most closely match the case of a porous ice regolith treated by Tokano, but with some apparent differences between the northern and southern hemispheres. CIRS will extend its study of seasonal variations in surface temperature on Titan as Cassini continues through northern spring.

  16. Cloud Condensation in Titan's Lower Stratosphere

    NASA Technical Reports Server (NTRS)

    Romani, Paul N.; Anderson, Carrie M.

    2011-01-01

    A 1-D condensation model is developed for the purpose of reproducing ice clouds in Titan's lower stratosphere observed by the Composite Infrared Spectrometer (CIRS) onboard Cassini. Hydrogen cyanide (HCN), cyanoacetylene (HC3N), and ethane (C2H6) vapors are treated as chemically inert gas species that flow from an upper boundary at 500 km to a condensation sink near Titan's tropopause (-45 km). Gas vertical profiles are determined from eddy mixing and a downward flux at the upper boundary. The condensation sink is based upon diffusive growth of the cloud particles and is proportional to the degree of supersaturation in the cloud formation regIOn. Observations of the vapor phase abundances above the condensation levels and the locations and properties of the ice clouds provide constraints on the free parameters in the model. Vapor phase abundances are determined from CIRS mid-IR observations, whereas cloud particle sizes, altitudes, and latitudinal distributions are derived from analyses of CIRS far-IR observations of Titan. Specific cloud constraints include: I) mean particle radii of2-3 J.lm inferred from the V6 506 cm- band of HC3N, 2) latitudinal abundance distributions of condensed nitriles, inferred from a composite emission feature that peaks at 160/cm , and 3) a possible hydrocarbon cloud layer at high latitudes, located near an altitude of 60 km, which peaks between 60 and 80 cm l . Nitrile abundances appear to diminish substantially at high northern latitudes over the time period 2005 to 2010 (northern mid winter to early spring). Use of multiple gas species provides a consistency check on the eddy mixing coefficient profile. The flux at the upper boundary is the net column chemical production from the upper atmosphere and provides a constraint on chemical pathways leading to the production of these compounds. Comparison of the differing lifetimes, vapor phase transport, vapor phase loss rate, and particle sedimentation, sheds light on temporal stability

  17. Global map of Titan's dune fields

    NASA Astrophysics Data System (ADS)

    Le Corre, L.; Le Mouélic, S.; Sotin, C.; Barnes, J. W.; Brown, R. H.; Baines, K.; Buratti, B.; Clark, R.; Nicholson, P.

    2008-09-01

    Introduction Methane is the second major constituent of Titan's atmosphere; but it should be totally removed at least in ten million years by photochemistry in the stratosphere and condensation in the troposphere [1]. The first process produces hydrocarbons which form the haze and can condensate onto the surface. The second process causes methane rains on the surface, which carve channels networks. The loss of methane is possibly balanced by outgassing during cryovolcanic event [2]. But hydrocarbons grains deposited onto the surface cannot be recycled. They may be stored in the dunes [3], which were first seen by SAR (Synthetic Aperture Radar) [4]. We focus our study on the mapping of the dune fields in order to determine their global distribution. The aim is to constrain the amount of hydrocarbon material existing in the dunes, and to relate it to the duration of the methane cycle. Data from the Visual and Infrared Mapping Spectrometer (VIMS) and RADAR instruments onboard Cassini spacecraft can be used to map Titan's surface. Infrared images, which are mainly sensitive to composition and grain size, are very complementary to the microwave measurements which depend mainly on roughness and topography. We used spectral criteria after empirical correction of aerosols to map the distribution of heterogeneous units on Titan [5]. These units are compared with SAR images in overlapping regions. Titan's surface mosaics with VIMS VIMS probes the first ten of microns of the ground in seven narrow atmospheric windows in the 0.88 to 5.11 μm wavelength range. We built infrared mosaics with cubes sorted by spatial resolution, by keeping cubes corresponding to favorable observing conditions (incidence, emergence, phase and time exposure). Band ratios were computed and combined in false color composite images (red as 1.59/1.27-μm, green as 2.03/1.27-μm and blue as 1.27/1.08-μm). Band ratios are useful to minimize the effect of illuminating conditions and albedo variations [6

  18. Seasonal Surface Temperature Changes on Titan

    NASA Astrophysics Data System (ADS)

    Jennings, Donald E.; Cottini, Valeria; Nixon, Conor A.; Coustenis, Athena; Tokano, Tetsuya

    2015-11-01

    The Composite Infrared Spectrometer (CIRS) on Cassini has been measuring surface brightness temperatures on Titan since 2004 (Jennings et al. 2011; Cottini et al. 2012; Tan et al. 2015). Radiation from the surface reaches space through a window of minimum opacity in Titan’s atmosphere near 19 microns wavelength. We mapped surface temperatures in five time periods, each about 2 years, centered on solar longitudes Ls = 313°, 335°, 0°, 28° and 53° degrees. Using zonally-averaged spectra binned in 10-degree latitude intervals, we clearly see the seasonal progression of the pole-to-pole temperature distribution. Whereas peak temperatures in the vicinity of the Equator have been close to 94 K throughout the Cassini mission, early in the mission temperatures at the North Pole were as low as 90 K and at the South Pole were 92 K. Late in the mission the pattern has reversed: 92 K in the north and 90 K in the south. Over 2005 to 2014 the peak temperature moved in latitude from about 15 S to 15 N. We estimate a seasonal lag of 0.2 Titan month. In 2010 the temperature distribution was approximately symmetric north and south, agreeing with Voyager 1 from one Titan year earlier. The surface temperatures follow closely the predictions of Tokano (2005). Our measurements may indicate a lower thermal inertia in the south than in the north.Jennings, D.E. et al., ApJ Lett. 737, L15 (2011)Cottini, V. et al., 2012. Planet. Space Sci. 60, 62 (2012)Tan, S. P. et al., Icarus 250, 64 (2015)Tokano, T., Icarus 204, 619 (2005)

  19. Solar cycle modulation of Titan's ionosphere

    NASA Astrophysics Data System (ADS)

    Edberg, N. J. T.; Andrews, D. J.; Shebanits, O.; Ågren, K.; Wahlund, J.-E.; Opgenoorth, H. J.; Cravens, T. E.; Girazian, Z.

    2013-08-01

    During the six Cassini Titan flybys T83-T88 (May 2012 to November 2012) the electron density in the ionospheric peak region, as measured by the radio and plasma wave science instrument/Langmuir probe, has increased significantly, by 15-30%, compared to previous average. These measurements suggest that a long‒term change has occurred in the ionosphere of Titan, likely caused by the rise to the new solar maximum with increased EUV fluxes. We compare measurements from TA, TB, and T5, from the declining phase of solar cycle 23 to the recent T83-T88 measurements during cycle 24, since the solar irradiances from those two intervals are comparable. The peak electron densities normalized to a common solar zenith angle Nnorm from those two groups of flybys are comparable but increased compared to the solar minimum flybys (T16-T71). The integrated solar irradiance over the wavelengths 1-80nm, i.e., the solar energy flux, Fe, correlates well with the observed ionospheric peak density values. Chapman layer theory predicts that Nnorm∝Fek, with k=0.5. We find observationally that the exponent k=0.54±0.18. Hence, the observations are in good agreement with theory despite the fact that many assumptions in Chapman theory are violated. This is also in good agreement with a similar study by Girazian and Withers (2013) on the ionosphere of Mars. We use this power law to estimate the peak electron density at the subsolar point of Titan during solar maximum conditions and find it to be about 6500cm-3, i.e., 85-160% more than has been measured during the entire Cassini mission.

  20. Atmospheric drag model for Cassini orbit determination during low altitude Titan flybys

    NASA Technical Reports Server (NTRS)

    Pelletier, F. J.; Antreasian, P. G.; Bordi, J. J.; Criddle, K. E.; Ionasescu, R.; Jacobson, R. A.; Mackenzie, R. A.; Parcher, D. W.; Stauch, J. R.

    2006-01-01

    On April 16, 2005, the Cassini spacecraft performed its lowest altitude flyby of Titan to date, the Titan-5 flyby, flying 1027 km above the surface of Titan. This document discusses the development of a Titan atmospheric drag model for the purpose of the orbit determination of Cassini. Results will be presented for the Titan A flyby, the Titan-5 flyby as well as the most recent low altitude Titan flyby, Titan-7. Different solutions will be compared against OD performance in terms of the flyby B-plane parameters, spacecraft thrusting activity and drag estimates. These low altitude Titan flybys were an excellent opportunity to observe the effect of Titan's atmospheric drag on the orbit determination solution and results show that the drag was successfully modeled to provide accurate flyby solutions.

  1. Formation and Evolution of Titan's Atmosphere

    NASA Astrophysics Data System (ADS)

    Coustenis, Athena

    2005-01-01

    The origin and evolution of Titan’s enigmatic atmosphere is reviewed. Starting with the present-day volatile inventory, the question of what was the original composition on Titan and how a satellite of similar size to other Galilean moons managed to acquire and hold on to the required material is discussed. In particular the possible sources and sinks of the main mother molecules (nitrogen, methane and oxygen) are investigated in view of the most recent models and laboratory experiments. The answers expected to be provided by the instruments aboard the Cassini-Huygens mission to some of the most prominent current questions regarding Titan’s atmosphere are defined.

  2. Phase 1 Final Report: Titan Submarine

    NASA Technical Reports Server (NTRS)

    Oleson, Steven R.; Lorenz, Ralph D.; Paul, Michael V.

    2015-01-01

    The conceptual design of a submarine for Saturn's moon Titan was a funded NASA Innovative Advanced Concepts (NIAC) Phase 1 for 2014. The proposal stated the desire to investigate what science a submarine for Titan's liquid hydrocarbon seas might accomplish and what that submarine might look like. Focusing on a flagship class science system (100 kg), it was found that a submersible platform can accomplish extensive science both above and below the surface of the Kraken Mare. Submerged science includes mapping using side-looking sonar, imaging and spectroscopy of the lake, as well as sampling of the lake's bottom and shallow shoreline. While surfaced, the submarine will not only sense weather conditions (including the interaction between the liquid and atmosphere) but also image the shoreline, as much as 2 km inland. This imaging requirement pushed the landing date to Titan's next summer period (2047) to allow for lighted conditions, as well as direct-to-Earth communication, avoiding the need for a separate relay orbiter spacecraft. Submerged and surfaced investigation are key to understanding both the hydrological cycle of Titan as well as gather hints to how life may have begun on Earth using liquid, sediment, and chemical interactions. An estimated 25 Mb of data per day would be generated by the various science packages. Most of the science packages (electronics at least) can be safely kept inside the submarine pressure vessel and warmed by the isotope power system.The baseline 90-day mission would be to sail submerged and surfaced around and through Kraken Mare investigating the shoreline and inlets to evaluate the sedimentary interaction both on the surface and then below. Depths of Kraken have yet to be sensed (Ligeia to the north is thought to be 200 m (656 ft) deep), but a maximum depth of 1,000 m (3,281 ft) for Kraken Mare was assumed for the design). The sub would spend 20 d at the interface between Kraken Mare and Ligeia Mare for clues to the drainage of

  3. Life on Titan: Theorem of existance

    NASA Astrophysics Data System (ADS)

    Potashko, O.

    Volcanoes engender life on heavenly bodies; they are pacemakers of life[1]. All planets during their period of formation pass through volcanism hence - all planets and their satellites pass through life. Tracks of life If we want to find tracks of life -- most promising places are places with volcanic activity, current or past. In the case of just-in-time volcanic activity we have 100% probability to find a life. Therefore the most perspective ``search for life'' are Io and comets, further would be Venus, Jupiter, Saturn, their satellites and first of all -- Titan. Titan has atmosphere. It might be result of high volcanic activity -- from one side, from other side atmosphere is a necessary condition development life from procaryota to eucaryota. Existence of a planet means that all its elements after hydrogen formed just there inside a planet. The forming of the elements leads to the formation of mineral and organic substances and further to the organic life. Development of the life depends upon many factors, e.g. the distance from star/s. The intensity of the processes of the element formation is inversely to the distance from the star. Therefore we may suppose that the intensity of the life in Mercury was very high. Hence we may detect tracks of life in Mercury, particularly near volcanoes. The distance from the star is only one parameter and now Titan looks very active -- mainly due to interior reason. Its atmosphere compounds are analogous to comet tail compounds. Their collation may lead to interesting result as progress occurs at one of them. Volcanic activity is as a source of life origin as well a reason for a death of life. It depends upon the thickness of planet crust. In the case of small thickness of a crust the probability is high that volcanoes may destroy a life on a planet -- like Noachian deluge. Destroying of the life under volcano influences doesn't lead to full dead. As result we would have periodic Noachian deluge or nuclear winter. These

  4. Global map of Titan's dune fields

    NASA Astrophysics Data System (ADS)

    Le Corre, L.; Le Mouélic, S.; Sotin, C.; Barnes, J. W.; Brown, R. H.; Baines, K.; Buratti, B.; Clark, R.; Nicholson, P.

    2008-09-01

    Introduction Methane is the second major constituent of Titan's atmosphere; but it should be totally removed at least in ten million years by photochemistry in the stratosphere and condensation in the troposphere [1]. The first process produces hydrocarbons which form the haze and can condensate onto the surface. The second process causes methane rains on the surface, which carve channels networks. The loss of methane is possibly balanced by outgassing during cryovolcanic event [2]. But hydrocarbons grains deposited onto the surface cannot be recycled. They may be stored in the dunes [3], which were first seen by SAR (Synthetic Aperture Radar) [4]. We focus our study on the mapping of the dune fields in order to determine their global distribution. The aim is to constrain the amount of hydrocarbon material existing in the dunes, and to relate it to the duration of the methane cycle. Data from the Visual and Infrared Mapping Spectrometer (VIMS) and RADAR instruments onboard Cassini spacecraft can be used to map Titan's surface. Infrared images, which are mainly sensitive to composition and grain size, are very complementary to the microwave measurements which depend mainly on roughness and topography. We used spectral criteria after empirical correction of aerosols to map the distribution of heterogeneous units on Titan [5]. These units are compared with SAR images in overlapping regions. Titan's surface mosaics with VIMS VIMS probes the first ten of microns of the ground in seven narrow atmospheric windows in the 0.88 to 5.11 μm wavelength range. We built infrared mosaics with cubes sorted by spatial resolution, by keeping cubes corresponding to favorable observing conditions (incidence, emergence, phase and time exposure). Band ratios were computed and combined in false color composite images (red as 1.59/1.27-μm, green as 2.03/1.27-μm and blue as 1.27/1.08-μm). Band ratios are useful to minimize the effect of illuminating conditions and albedo variations [6

  5. Scalable k-means statistics with Titan.

    SciTech Connect

    Thompson, David C.; Bennett, Janine C.; Pebay, Philippe Pierre

    2009-11-01

    This report summarizes existing statistical engines in VTK/Titan and presents both the serial and parallel k-means statistics engines. It is a sequel to [PT08], [BPRT09], and [PT09] which studied the parallel descriptive, correlative, multi-correlative, principal component analysis, and contingency engines. The ease of use of the new parallel k-means engine is illustrated by the means of C++ code snippets and algorithm verification is provided. This report justifies the design of the statistics engines with parallel scalability in mind, and provides scalability and speed-up analysis results for the k-means engine.

  6. Low surface pressure models for Titan's atmosphere

    NASA Technical Reports Server (NTRS)

    Caldwell, J.

    1978-01-01

    The inversion model for the atmosphere of Titan is reviewed. The basic features of the model are: a cold surface (80 K), a warm stratosphere (160 K) and a low surface pressure (20 mbar). The model is consistent with all existing thermal infrared spectrophotometry, but it cannot preclude the existence of an opaque, cloud, thick atmosphere. The model excludes other gases than methane as bulk constituents. Radio wavelengths observations, including recent data from the very large array, are discussed. These long wavelength observations may be the only direct means of sampling the surface environment before an entry probe or flyby.

  7. High Performance Calcium Titanate Nanoparticle ER Fluids

    NASA Astrophysics Data System (ADS)

    Wang, Xuezhao; Shen, Rong; Wen, Weijia; Lu, Kunquan

    A type of calcium titanate (CTO) nanoparticles was synthesized by means of wet chemical method [1] without coating on the particles. The CTO/silicone oil ER fluid exhibits excellent electrorheological properties: high shear stress (~50-100 kPa) under dc electric field, a low current density (less than 2μA/cm2 at 5kV/mm), and long term stability against sedimentation. Although there are not special additives in the ER fluids, it is found from the chemical analysis that a trace of alkyl group, hydroxyl group, carbonyl group and some ions is remained in the particles which may dominate the ER response.

  8. Esophageal papilloma: Flexible endoscopic ablation by radiofrequency

    PubMed Central

    del Genio, Gianmattia; del Genio, Federica; Schettino, Pietro; Limongelli, Paolo; Tolone, Salvatore; Brusciano, Luigi; Avellino, Manuela; Vitiello, Chiara; Docimo, Giovanni; Pezzullo, Angelo; Docimo, Ludovico

    2015-01-01

    Squamous papilloma of the esophagus is a rare benign lesion of the esophagus. Radiofrequency ablation is an established endoscopic technique for the eradication of Barrett esophagus. No cases of endoscopic ablation of esophageal papilloma by radiofrequency ablation (RFA) have been reported. We report a case of esophageal papilloma successfully treated with a single session of radiofrequency ablation. Endoscopic ablation of the lesion was achieved by radiofrequency using a new catheter inserted through the working channel of endoscope. The esophageal ablated tissue was removed by a specifically designed cup. Complete ablation was confirmed at 3 mo by endoscopy with biopsies. This case supports feasibility and safety of as a new potential indication for BarrxTM RFA in patients with esophageal papilloma. PMID:25789102

  9. Reaction Profiles and Molecular Dynamics Simulations of Cyanide Radical Reactions Relevant to Titan's Atmosphere

    NASA Astrophysics Data System (ADS)

    Trinidad Pérez-Rivera, Danilo; Romani, Paul N.; Lopez-Encarnacion, Juan Manuel

    2016-10-01

    Titan's atmosphere is arguably the atmosphere of greatest interest that we have an abundance of data for from both ground based and spacecraft observations. As we have learned more about Titan's atmospheric composition, the presence of pre-biotic molecules in its atmosphere has generated more and more fascination about the photochemical process and pathways it its atmosphere. Our computational laboratory has been extensively working throughout the past year characterizing nitrile synthesis reactions, making significant progress on the energetics and dynamics of the reactions of .CN with the hydrocarbons acetylene (C2H2), propylene (CH3CCH), and benzene (C6H6), developing a clear picture of the mechanistic aspects through which these three reactions proceed. Specifically, first principles calculations of the reaction profiles and molecular dynamics studies for gas-phase reactions of .CN and C2H2, .CN and CH3CCH, and .CN and C6H6 have been carried out. A very accurate determination of potential energy surfaces of these reactions will allow us to compute the reaction rates which are indispensable for photochemical modeling of Titan's atmosphere.The work at University of Puerto Rico at Cayey was supported by Puerto Rico NASA EPSCoR IDEAS-ER program (2015-2016) and DTPR was sponsored by the Puerto Rico NASA Space Grant Consortium Fellowship. *E-mail: juan.lopez15@upr.edu

  10. Projects To Probe Titan's Surface Composition and Development of Atmospheric Removal Models for Cassini VIMS Data

    NASA Astrophysics Data System (ADS)

    Pitman, K. M.; Buratti, B. J.; Baines, K. H.; West, R. A.; Wolff, M. J.; Brown, R. H.

    2007-05-01

    In this work, we will describe recent projects performed by our group at the Jet Propulsion Laboratory, California Institute of Technology involving I/F data of Titan's surface acquired by Cassini's Visual and Infrared Mapping Spectrometer (VIMS), including the next stage of development of methods to de-gas and de-fog VIMS images. VIMS I/F spectra include contributions from both surface and atmospheric signal; therefore, current spectral data analysis necessarily focuses on portions of VIMS I/F spectra where atmospheric methane and scattering by haze is at a minimum. However, atmospheric opacity clears enough between wavelengths of 1 and 2 microns to provide strong potential to view complex landforms if a proper atmospheric correction can be applied. Plane- parallel radiative transfer (RT) correction methods have been used successfully in surface-atmospheric separation retrievals for Mars and offer some utility for VIMS observations of Titan that are away from the limb. In a previous work (Pitman et al. 2007, LPSC XXXVIII, p. 1164), we determined which inputs to radiative transfer models must be updated, given results from recent meetings and literature, and evaluated two plane-parallel RT models (adding-doubling, discrete ordinates) to determine which is more easily customized for surface- atmospheric separation of Titan. In this work, we report our progress on replacing Voyager with Cassini-Huygens inputs and how these models currently compare. Work performed under contract to NASA and by appointment to the NASA Postdoctoral Program (ORAU).

  11. Observations of H2O in Titan's atmosphere with Herschel

    NASA Astrophysics Data System (ADS)

    Moreno, R.; Lellouch, E.; Lara, L. M.; Courtin, R.; Hartogh, P.; Rengel, M.

    2012-04-01

    Disk averaged observations of several H2O far infrared lines in Titan’s atmosphere were performed with the Herschel Space Observatory, as part of the guaranteed time key program "Water and related chemistry in the Solar System" (HssO, see Hartogh et al 2011). Two instruments were used: (i) HIFI, a heterodyne instrument (R~ 106 ) in the sub-millimeter, which measured the H2O(110-101) rotational transition at 557 GHz on June 10 and Dec. 31, 2010 (ii) PACS, a photoconductor spectrometer (R~103) which measured three water lines at 108.1, 75.4 and 66.4 microns on June 22, 2010. Additional PACS measurements at 66.4 microns on Dec. 15 and 22, 2010 and on July 09, 2011, do not show any significant line intensity variation with time, nor between the leading/trailing sides (i.e. longitude). Spectra were analyzed with a line-by-line radiative transfer code accounting for spherical geometry (Moreno et al. 2011). This model considers the H2O molecular opacity from JPL catalog (Pickett et al. 1998) and also includes collision-induced opacities N2-N2, N2-CH4 and CH4-CH4 (Borysow and Frommhold 1986, 1987, Borysow and Tang 1993). Far infrared aerosol opacities derived by CIRS were included, following Anderson and Samuelson (2011) for their vertical distribution and spectral dependencies. Analysis of the 557 GHz narrow line (FWHM ~ 2 MHz) indicates that it originates at altitudes above 300 km, while lines measured with PACS probe mainly deeper levels (80-150 km). The HIFI and PACS observations are fitted simultaneously, considering a vertical distribution of H2O mixing ratio which follows a power law dependency q=q0(P/P0)n, where q0 is the mixing ratio at some reference pressure level P0, taken near the expected condensation level. Model fits will be presented, and compared with previously proposed H2O vertical distributions. We show in particular that both the steep profile proposed by Lara et al. (1996) (and adopted by Coustenis et al. (1998) to model the first detection of H2O

  12. Escape of Nitrogen from Titan's atmosphere driven by magnetospheric and pick-up ions

    NASA Astrophysics Data System (ADS)

    Michael, M.; Liu, M.; Johnson, R. E.; Luhmann, J. G.; Shematovich, V. I.

    2003-05-01

    The nitrogen rich atmosphere of Titan is a significant source of the neutrals in Saturn's magnetosphere. As Titan does not posses an intrinsic magnetic field, energetic Kronian magnetospheric ions penetrate Titan's atmospheric exobase as can local pick-up ions (e.g. Shematovich et al. 2003). Penetration by energetic ions is described here using a 3-D Monte Carlo model. The incident ions can lead directly or indirectly to the production of fast neutrals that collide with other atmospheric neutrals. This leads to dissociation and the ejection of both atomic and molecular nitrogen. The recently calculated dissociation cross sections of N2 are used in the present model (Tully and Johnson 2002). The incident flux of slowed magentospheric N+ ions and pick-up C2H_5+ ions is estimated from the work of Brecht et al. (2000). These ions of energy less than 1.2 keV are shown to be more efficient in ejecting material from Titan's atmosphere than the higher energy corotating ions described in early estimates (Lammer et al. 1998). This incident flux of ions are used in the model and the results are used as a source of nitrogen for the Saturnian plasma torus. Acknowledgment: This work is supported by NASA:s Planetary Atmospheres Program. References Brecht, S.H., J.G. Luhmann, and D.J. Larson, J. Geophys. Res., 105, 13119, 2000. Lammer, H. W. Stumptner, and S.J. Bauer, Planet. Space Sci., 46, 1207, 1998. Shematovich, V.I., R.E. Johnson, M. Michael and J.G. Luhmann, J. Geophys. Res., in press, 2003. Tully, C., R.E. Johnson, J. Chem. Phys. 117, 6556-6561, 2002.

  13. Effect of ammonia on the stability of clathrate hydrates: experimental study and implications for Titan

    NASA Astrophysics Data System (ADS)

    Choukroun, M.; Ibourichene, A.; Smythe, W. D.; Mielke, R. E.; Barmatz, M.; Hodyss, R. P.

    2013-12-01

    The likely presence of clathrate hydrates on Titan has long been inferred from cosmochemical, thermal, and thermodynamic models. As gas-laden icy structures (up to 15 mol%), they may be internal reservoirs of methane and other atmospheric gasses, and their dissociation during cryovolcanic activity could be a main contributor to the replenishment of Titan's atmospheric methane. However, the controversial nature of the few cryovolcanic features tentatively detected on Titan by the Cassini spacecraft questions our current understanding of the modalities of outgassing processes. The paucity of data on the stability of clathrate hydrates in presence of ammonia (likely source of Titan's atmospheric nitrogen) hinders our capability to address outgassing processes. We are conducting an experimental study in the ternary systems H2O-CH4-NH3 and H2O-THF-NH3. Phase diagrams of the former are constructed under pressures up to 100 bars using a high-pressure cryogenic calorimeter, while the latter is investigated at atmospheric pressure using a liquid nitrogen cooled cryostage coupled to a microscope and a Raman spectrometer. The main preliminary results are: 1/ although ammonia does affect the stability of clathrate hydrates, its influence appears lower than on the melting of water ice; 2/ the dissociation proceeds incongruently, similarly to the incongruent melting of water ice in the H2O-NH3 system. These results and their implications will be presented at the meeting. This work has been conducted at the Jet Propulsion Laboratory, California Institute of Technology, under contract to NASA. Copyright 2013, Caltech. Support by the NASA Outer Planets Research Program and government sponsorship acknowledged.

  14. [Catheter ablation of persistent atrial fibrillation : pulmonary vein isolation, ablation of fractionated electrograms, stepwise approach or rotor ablation?].

    PubMed

    Scherr, D

    2015-02-01

    Catheter ablation is an established treatment option for patients with atrial fibrillation (AF). In paroxysmal AF ablation, pulmonary vein isolation alone is a well-defined procedural endpoint, leading to success rates of up to 80% with multiple procedures over 5 years of follow-up. The success rate in persistent AF ablation is significantly more limited. This is partly due to the rudimentary understanding of the substrate maintaining persistent AF. Three main pathophysiological concepts for this arrhythmia exist: the multiple wavelet hypothesis, the concept of focal triggers, mainly located in the pulmonary veins and the rotor hypothesis. However, the targets and endpoints of persistent AF ablation are ill-defined and there is no consensus on the optimal ablation strategy in these patients. Based on these concepts, several ablation approaches for persistent AF have emerged: pulmonary vein isolation, the stepwise approach (i.e. pulmonary vein isolation, ablation of fractionated electrograms and linear ablation), magnetic resonance imaging (MRI) and rotor-based approaches. Currently, persistent AF ablation is a second-line therapy option to restore and maintain sinus rhythm. Several factors, such as the presence of structural heart disease, duration of persistent AF and dilatation and possibly also the degree of fibrosis of the left atrium should influence the decision to perform persistent AF ablation. PMID:25687615

  15. Microwave Ablation Compared with Radiofrequency Ablation for Breast Tissue in an Ex Vivo Bovine Udder Model

    SciTech Connect

    Tanaka, Toshihiro; Westphal, Saskia; Isfort, Peter; Braunschweig, Till; Penzkofer, Tobias Bruners, Philipp; Kichikawa, Kimihiko; Schmitz-Rode, Thomas Mahnken, Andreas H.

    2012-08-15

    Purpose: To compare the effectiveness of microwave (MW) ablation with radiofrequency (RF) ablation for treating breast tissue in a nonperfused ex vivo model of healthy bovine udder tissue. Materials and Methods: MW ablations were performed at power outputs of 25W, 35W, and 45W using a 915-MHz frequency generator and a 2-cm active tip antenna. RF ablations were performed with a bipolar RF system with 2- and 3-cm active tip electrodes. Tissue temperatures were continuously monitored during ablation. Results: The mean short-axis diameters of the coagulation zones were 1.34 {+-} 0.14, 1.45 {+-} 0.13, and 1.74 {+-} 0.11 cm for MW ablation at outputs of 25W, 35W, and 45W. For RF ablation, the corresponding values were 1.16 {+-} 0.09 and 1.26 {+-} 0.14 cm with electrodes having 2- and 3-cm active tips, respectively. The mean coagulation volumes were 2.27 {+-} 0.65, 2.85 {+-} 0.72, and 4.45 {+-} 0.47 cm{sup 3} for MW ablation at outputs of 25W, 35W, and 45W and 1.18 {+-} 0.30 and 2.29 {+-} 0.55 cm{sup 3} got RF ablation with 2- and 3-cm electrodes, respectively. MW ablations at 35W and 45W achieved significantly longer short-axis diameters than RF ablations (P < 0.05). The highest tissue temperature was achieved with MW ablation at 45W (P < 0.05). On histological examination, the extent of the ablation zone in MW ablations was less affected by tissue heterogeneity than that in RF ablations. Conclusion: MW ablation appears to be advantageous with respect to the volume of ablation and the shape of the margin of necrosis compared with RF ablation in an ex vivo bovine udder.

  16. PEROXOTITANATE- AND MONOSODIUM METAL-TITANATE COMPOUNDS AS INHIBITORS OF BACTERIAL GROWTH

    SciTech Connect

    Hobbs, D.

    2011-01-19

    Sodium titanates are ion-exchange materials that effectively bind a variety of metal ions over a wide pH range. Sodium titanates alone have no known adverse biological effects but metal-exchanged titanates (or metal titanates) can deliver metal ions to mammalian cells to alter cell processes in vitro. In this work, we test a hypothesis that metal-titanate compounds inhibit bacterial growth; demonstration of this principle is one prerequisite to developing metal-based, titanate-delivered antibacterial agents. Focusing initially on oral diseases, we exposed five species of oral bacteria to titanates for 24 h, with or without loading of Au(III), Pd(II), Pt(II), and Pt(IV), and measuring bacterial growth in planktonic assays through increases in optical density. In each experiment, bacterial growth was compared with control cultures of titanates or bacteria alone. We observed no suppression of bacterial growth by the sodium titanates alone, but significant (p < 0.05, two-sided t-tests) suppression was observed with metal-titanate compounds, particularly Au(III)-titanates, but with other metal titanates as well. Growth inhibition ranged from 15 to 100% depending on the metal ion and bacterial species involved. Furthermore, in specific cases, the titanates inhibited bacterial growth 5- to 375-fold versus metal ions alone, suggesting that titanates enhanced metal-bacteria interactions. This work supports further development of metal titanates as a novel class of antibacterials.

  17. Methane storms as a driver of Titan's dune orientation

    NASA Astrophysics Data System (ADS)

    Charnay, Benjamin; Barth, Erika; Rafkin, Scot; Narteau, Clément; Lebonnois, Sébastien; Rodriguez, Sébastien; Courrech Du Pont, Sylvain; Lucas, Antoine

    2015-05-01

    The equatorial regions of Saturn's moon Titan are covered by linear dunes that propagate eastwards. Global climate models (GCMs), however, predict westward mean surface winds at low latitudes on Titan, similar to the trade winds on Earth. This apparent contradiction has been attributed to Saturn's gravitational tides, large-scale topography and wind statistics, but none of these hypotheses fully explains the global eastward propagation of dunes in Titan's equatorial band. However, above altitudes of about 5 km, Titan's atmosphere is in eastward super-rotation, suggesting that this momentum may be delivered to the surface. Here we assess the influence of equatorial tropical methane storms--which develop at high altitudes during the equinox--on Titan's dune orientation, using mesoscale simulations of convective methane clouds with a GCM wind profile that includes super-rotation. We find that these storms produce fast eastward gust fronts above the surface that exceed the normal westward surface winds. These episodic gusts generated by tropical storms are expected to dominate aeolian transport, leading to eastward propagation of dunes. We therefore suggest a coupling between super-rotation, tropical methane storms and dune formation on Titan. This framework, applied to GCM predictions and analogies to some terrestrial dune fields, explains the linear shape, eastward propagation and poleward divergence of Titan's dunes, and implies an equatorial origin of dune sand.

  18. Solar Electric and Chemical Propulsion for a Titan Mission

    NASA Technical Reports Server (NTRS)

    Cupples, Michael; Green, Shaun E.; Donahue, Benjamin B.; Coverstone, Victoria L.

    2005-01-01

    Systems analyses were performed for a Titan Explorer Mission characterized by Earth-Saturn transfer stages using solar electric power generation and propulsion systems for primary interplanetary propulsion, and chemical propulsion for capture at Titan. An examination of a range of system factors was performed to determine their effect on the payload delivery capability to Titan. The effect of varying launch vehicle type, solar array power level, ion thruster number, specific impulse, trip time, and Titan capture stage chemical propellant choice was investigated. The major purpose of the study was to demonstrate the efficacy of applying advanced ion propulsion system technologies like NASA's Evolutionary Xenon Thruster (NEXT), coupled with state-of-the-art (SOA) and advanced chemical technologies to a Flagship class mission. This study demonstrated that a NASA Design Reference Mission (DRM) payload of 406 kg could be successfully delivered to Titan using the baseline advanced ion propulsion system in conjunction with SOA chemical propulsion for Titan capture. In addition, the SEPS/Chemical system of this study is compared to an all- chemical NASA DRM mission. Results showed that the NEXT- based SEPS/Chemical system was able to deliver the required payload to Titan in 5 years less transfer time and on a smaller launch vehicle than the SOA chemical option.

  19. Titan and habitable planets around M-dwarfs.

    PubMed

    Lunine, Jonathan I

    2010-01-01

    The Cassini-Huygens mission discovered an active "hydrologic cycle" on Saturn's giant moon Titan, in which methane takes the place of water. Shrouded by a dense nitrogen-methane atmosphere, Titan's surface is blanketed in the equatorial regions by dunes composed of solid organics, sculpted by wind and fluvial erosion, and dotted at the poles with lakes and seas of liquid methane and ethane. The underlying crust is almost certainly water ice, possibly in the form of gas hydrates (clathrate hydrates) dominated by methane as the included species. The processes that work the surface of Titan resemble in their overall balance no other moon in the solar system; instead, they are most like that of the Earth. The presence of methane in place of water, however, means that in any particular planetary system, a body like Titan will always be outside the orbit of an Earth-type planet. Around M-dwarfs, planets with a Titan-like climate will sit at 1 AU--a far more stable environment than the approximately 0.1 AU where Earth-like planets sit. However, an observable Titan-like exoplanet might have to be much larger than Titan itself to be observable, increasing the ratio of heat contributed to the surface atmosphere system from internal (geologic) processes versus photons from the parent star.

  20. Titan and habitable planets around M-dwarfs.

    PubMed

    Lunine, Jonathan I

    2010-01-01

    The Cassini-Huygens mission discovered an active "hydrologic cycle" on Saturn's giant moon Titan, in which methane takes the place of water. Shrouded by a dense nitrogen-methane atmosphere, Titan's surface is blanketed in the equatorial regions by dunes composed of solid organics, sculpted by wind and fluvial erosion, and dotted at the poles with lakes and seas of liquid methane and ethane. The underlying crust is almost certainly water ice, possibly in the form of gas hydrates (clathrate hydrates) dominated by methane as the included species. The processes that work the surface of Titan resemble in their overall balance no other moon in the solar system; instead, they are most like that of the Earth. The presence of methane in place of water, however, means that in any particular planetary system, a body like Titan will always be outside the orbit of an Earth-type planet. Around M-dwarfs, planets with a Titan-like climate will sit at 1 AU--a far more stable environment than the approximately 0.1 AU where Earth-like planets sit. However, an observable Titan-like exoplanet might have to be much larger than Titan itself to be observable, increasing the ratio of heat contributed to the surface atmosphere system from internal (geologic) processes versus photons from the parent star. PMID:21302558

  1. Likelihood of nitrogen condensation in Titan's present atmosphere

    NASA Astrophysics Data System (ADS)

    Tokano, Tetsuya%F. AA(Institut für Geophysik und Meteorologie, Universität zu Köln)

    2016-06-01

    Nitrogen condensation is considered to have taken place in Titan's atmosphere in the past when the atmosphere contained much less methane than today or the solar luminosity was smaller. On the other hand, it is not known for sure whether nitrogen condensation takes place on present-day Titan. Vertical temperature profiles in Titan's troposphere obtained Voyager, Huygens and Cassini do not reach the pressure-dependent nitrogen condensation temperature at any location, so that nitrogen condensation was probably not occurring along these profiles at the time of measurements. However, these spacecraft may not have sounded the coldest seasons and areas of Titan since they all took place in the seasons following perihelion. The seasonal cycle of temperature and nitrogen relative humidity in Titan's troposphere has been simulated by a general circulation model in an effort to explore possible areas and seasons of nitrogen condensation on present Titan. In contrast to the upper stratosphere, the seasonal temperature variation in the troposphere is more strongly controlled by Saturn's orbital eccentricity than by Saturn's obliquity. Consequently, the tropospheric temperature globally decreases between the northern vernal equinox and autumnal equinox and reaches the annual minimum around the northern autumnal equinox approximately one season after aphelion. It is possible if not certain that the polar atmosphere between 30 and 40 km altitude temporarily reach the nitrogen condensation temperature in this season and thereby causes liquid nitrogen clouds. Qualitative differences to the more common methane condensation as well as possible impact on Titan's weather are discussed.

  2. The atmospheric circulation and methane cycle in the TitanWRF and Titan MITgcm models

    NASA Astrophysics Data System (ADS)

    Lian, Yuan; Newman, Claire E.; Richardson, Mark I.

    2016-10-01

    We use the TitanWRF and Titan MITgcm to simulate the formation of stratospheric superrotation on Titan. The stratospheric wind speed reaches 180 m/s around both solstices. The MITgcm results appear similar to those from Titan WRF (Newman et al., 2011). However, despite the similar physics parameterizations such as radiative transfer and PBL mixing, the MITgcm produces a consistent minimum (about 5 to 15m/s depending on the season) near 50km above the surface. This result is comparable to the wind profile obtained by Huygens, though the observed wind minimum was between 75km and 80km above the surface. Attempts have been made to investigate what produces the wind minimum, e.g., turning off the diurnal cycle and removing surface thermal inertia. The wind minimum persists despite the effort, suggesting the feature may originate from interactions between zonal wind and downward propagating waves. We further examine the effect of topography on the wind structure. The stratospheric superrotation in these simulations is significantly slower than that in the simulations without topography, with maximum speed of 110m/s as opposed to previously simulated 180m/s. The wind minimum near 50km, however, still exists in the MITgcm. Also, results suggest that the near surface winds are primarily guided by topography, and are less affected by solar heating on the surface. Another distinct result, compared to the cases without topography in both TitanWRF and the MITgcm, is that the near surface winds in the equatorial region exhibit strong eastward components, which may help to explain the combination of dune orientations and transport directions inferred from imaging. Lastly, we introduce an active methane cycle using a simplified Betts-Miller scheme (similar to Mitchell et al, 2009) to represent moist convection associated with the methane cycle in the troposphere. We will explore the impact of the new scheme on the methane cycle, and compare its realism to that of the large

  3. Titan LEAF: A Sky Rover Granting Targeted Access to Titan's Lakes and Plains

    NASA Astrophysics Data System (ADS)

    Ross, Floyd; Lee, Greg; Sokol, Daniel; Goldman, Benjamin; Bolisay, Linden

    2016-10-01

    Northrop Grumman, in collaboration with L'Garde Inc. and Global Aerospace Corporation (GAC), has been developing the Titan Lifting Entry Atmospheric Flight (T-LEAF) sky rover to roam the atmosphere and observe at close quarters the lakes and plains of Titan. T-LEAF also supports surface exploration and science by providing precision delivery of in situ instruments to the surface.T-LEAF is a maneuverable, buoyant air vehicle. Its aerodynamic shape provides its maneuverability, and its internal helium envelope reduces propulsion power requirements and also the risk of crashing. Because of these features, T-LEAF is not restricted to following prevailing wind patterns. This freedom of mobility allows it be commanded to follow the shorelines of Titan's methane lakes, for example, or to target very specific surface locations.T-LEAF utilizes a variable power propulsion system, from high power at ~200W to low power at ~50W. High power mode uses the propellers and control surfaces for additional mobility and maneuverability. It also allows the vehicle to hover over specific locations for long duration surface observations. Low power mode utilizes GAC's Titan Winged Aerobot (TWA) concept, currently being developed with NASA funding, which achieves guided flight without the use of propellers or control surfaces. Although slower than high powered flight, this mode grants increased power to science instruments while still maintaining control over direction of travel.Additionally, T-LEAF is its own entry vehicle, with its leading edges protected by flexible thermal protection system (f-TPS) materials already being tested by NASA's Hypersonic Inflatable Aerodynamic Decelerator (HIAD) group. This f-TPS technology allows T-LEAF to inflate in space, like HIAD, and then enter the atmosphere fully deployed. This approach accommodates entry velocities from as low as ~1.8 km/s if entering from Titan orbit, up to ~6 km/s if entering directly from Saturn orbit, like the Huygens probe

  4. Ion Neutral Mass Spectrometer Measurements from Titan

    NASA Technical Reports Server (NTRS)

    Waite, J. H., Jr.; Niemann, H.; Yelle, R. V.; Kasprzak, W.; Cravens, T.; Luhmann, J.; McNutt, R.; Ip, W.-H.; Gell, D.; Muller-Wordag, I. C. F.

    2005-01-01

    Introduction: The Ion Neutral Mass Spectrometer (INMS) aboard the Cassini orbiter has obtained the first in situ composition measurements of the neutral densities of molecular nitrogen, methane, argon, and a host of stable carbon-nitrile compounds in its first flyby of Titan. The bulk composition and thermal structure of the moon s upper atmosphere do not appear to be changed since the Voyager flyby in 1979. However, the more sensitive techniques provided by modern in-situ mass spectrometry also give evidence for large-spatial-scale large-amplitude atmospheric waves in the upper atmosphere and for a plethora of stable carbon-nitrile compounds above 1174 km. Furthermore, they allow the first direct measurements of isotopes of nitrogen, carbon, and argon, which provide interesting clues about the evolution of the atmosphere. The atmosphere was first accreted as ammonia and ammonia ices from the Saturn sub-nebula. Subsequent photochemistry likely converted the atmosphere into molecular nitrogen. The early atmosphere was 1.5 to 5 times more substantial and was lost via escape over the intervening 4.5 billion years due to the reduced gravity associated with the relatively small mass of Titan. Carbon in the form of methane has continued to outgas over time from the interior with much of it being deposited in the form of complex hydrocarbons on the surface and some of it also being lost to space.

  5. Titan's corona: The contribution of exothermic chemistry

    NASA Astrophysics Data System (ADS)

    De La Haye, V.; Waite, J. H.; Cravens, T. E.; Nagy, A. F.; Johnson, R. E.; Lebonnois, S.; Robertson, I. P.

    2007-11-01

    The contribution of exothermic ion and neutral chemistry to Titan's corona is studied. The production rates for fast neutrals N 2, CH 4, H, H 2, 3CH 2, CH 3, C 2H 4, C 2H 5, C 2H 6, N( 4S), NH, and HCN are determined using a coupled ion and neutral model of Titan's upper atmosphere. After production, the formation of the suprathermal particles is modeled using a two-stream simulation, as they travel simultaneously through a thermal mixture of N 2, CH 4, and H 2. The resulting suprathermal fluxes, hot density profiles, and energy distributions are compared to the N 2 and CH 4 INMS exospheric data presented in [De La Haye, V., Waite Jr., J.H., Johnson, R.E., Yelle, R.V., Cravens, T.E., Luhmann, J.G., Kasprzak, W.T., Gell, D.A., Magee, B., Leblanc, F., Michael, M., Jurac, S., Robertson, I.P., 2007. J. Geophys. Res., doi:10.1029/2006JA012222, in press], and are found insufficient for producing the suprathermal populations measured. Global losses of nitrogen atoms and carbon atoms in all forms due to exothermic chemistry are estimated to be 8.3×10 Ns and 7.2×10 Cs.

  6. The Huygens Mission at Titan: Results Highlights

    NASA Technical Reports Server (NTRS)

    Lebreton, J.-P.; Matson, D. L.

    2005-01-01

    After a 7-year interplanetary journey onboard the Cassini Orbiter, the Huygens Probe was released on 25 December at 02:00 UTC. It entered in the atmosphere of Titan on 14 January at about 09:06 UTC. Following the 4-min entry, 3 parachutes were deployed in sequence. The descent under parachute lasted slightly less than 2 1/2 hours. After a soft landing at about 5 m/s, the probe continued to function for several hours on the surface. During the descent under parachute and on the surface, Huygens transmitted its data at 8 kbps on two redundant channels to the over-flying Orbiter which approached Titan at a closest distance of 60000 km about 1/2 hour before landing. Data were successfully received only on one channel due to a configuration error of the receiver of the channel which was driven by the ultra-stable oscillators (USO) of the Doppler Wind Experiment (DWE). The Orbiter received data during the descent under parachute and for 72 minutes on the surface until its path moved it outside the beam of the transmitting antennas of the probe resting on the surface and at the same time as the Orbiter went below the Horizon. Additional information is included in the original extended abstract.

  7. Seasonal Changes in Surface Temperatures on Titan

    NASA Technical Reports Server (NTRS)

    Jennings, D. E.; Cottini, V.; Nixon, C. A.

    2010-01-01

    The surface brightness temperatures on Titan have been measured by the Composite Infrared Spectrometer (CIRS) aboard Cassini during the period spanning late northern winter through vernal equinox. CIRS observes radiance from the surface through a spectral window at 19 microns where the atmosphere has an opacity minimum [I]. CIRS is now seeing a shift in the latitudinal distribution of temperatures froth a distinctly warmer south to a more symmetrical north -south pattern, similar to that found by Voyager IRIS [2,3] at the time of the previous vernal equinox. Near the equator the temperatures remain close to the 93.7 K value found at the surface by Huygens [4]. From the equator to the poles the temperature gradients are 2-3 K. When compared with predictions froth general circulation models [5] the measured temperatures and their seasonal changes constrain the possible types of surface material. As Cassini continues through Titan's northern spring CiRS will extend its, global coverage to took for correlations between surface temperatures and albedo and to search for diurnal temperature variations

  8. Titan's Plains: Global Distribution and Possible Origin

    NASA Astrophysics Data System (ADS)

    Lopes, R. M.; Le Gall, A.; Kirk, R. L.; Kargel, J. S.; Stofan, E. R.; Mitchell, K. L.; Lucas, A.; Janssen, M. A.; Wall, S. D.; Malaska, M. J.

    2012-12-01

    Titan's diverse and Earth-like geologic features have been mapped and interpreted based on their morphological characteristics (Lopes et al., 2010, Icarus 205; Aharonson et al., 2012, Titan: Surface, Atmosphere, Magnetosphere, Cambridge University Press). While the interpretation for the origin of some units, such as dunes and well-preserved impact craters, has been relatively straightforward, others have been more challenging. In particular, the undifferentiated plains first mapped by Lopes et al. (2010) remain mysterious. These vast expanses, mostly found at mid-latitudes are relatively featureless and appear to have low relief. Their gradational boundaries and paucity of features in SAR data make geologic interpretation particularly difficult using only this dataset. Plains may be sedimentary in origin, resulting from fluvial or lacustrine deposition or accumulation of photolysis products created in the upper atmosphere. Alternatively, the plains may be cryovolcanic, consisting of overlapping flows of low relief, obscured by accumulation of sediments. In this paper, we use SAR, radiometry, scatterometry, and SARTopo data to examine the characteristics of the plains and compare them with other geologic units. We also compare their global distribution with that of other units and examine the implications of a possible cryovolcanic origin.

  9. A physical model of Titan's clouds

    NASA Technical Reports Server (NTRS)

    Toon, O. B.; Pollack, J. B.; Turco, R. P.

    1980-01-01

    A physical model of the formation and growth of aerosols in the atmosphere of Titan has been constructed in light of the observed correlation between variations in Titan's albedo and the sunspot cycle. The model was developed to fit spectral observations of deep methane bands, pressures, temperature distributions, and cloud structure, and is based on a one-dimensional physical-chemical model developed to simulate the earth's stratospheric aerosol layer. Sensitivity tests reveal the model parameters to be relatively insensitive to particle shape but sensitive to particle density, with high particle densities requiring larger aerosol mass production rates to produce compatible clouds. Solution of the aerosol continuity equations for particles of sizes 13 A to about 3 microns indicates the importance of a warm upper atmosphere and a high-altitude mass injection layer, and the production of aerosols at very low aerosol optical depths. Limits are obtained for the chemical production of aerosol mass and the eddy diffusion coefficient, and it is found that an increase in mass input causes a decrease in mean particle size.

  10. Big Bang Cosmic Titanic: Cause for Concern?

    NASA Astrophysics Data System (ADS)

    Gentry, Robert

    2013-04-01

    This abstract alerts physicists to a situation that, unless soon addressed, may yet affect PRL integrity. I refer to Stanley Brown's and DAE Robert Caldwell's rejection of PRL submission LJ12135, A Cosmic Titanic: Big Bang Cosmology Unravels Upon Discovery of Serious Flaws in Its Foundational Expansion Redshift Assumption, by their claim that BB is an established theory while ignoring our paper's Titanic, namely, that BB's foundational spacetime expansion redshifts assumption has now been proven to be irrefutably false because it is contradicted by our seminal discovery that GPS operation unequivocally proves that GR effects do not produce in-flight photon wavelength changes demanded by this central assumption. This discovery causes the big bang to collapse as quickly as did Ptolemaic cosmology when Copernicus discovered its foundational assumption was heliocentric, not geocentric. Additional evidence that something is amiss in PRL's treatment of LJ12135 comes from both Brown and EiC Gene Spouse agreeing to meet at my exhibit during last year's Atlanta APS to discuss this cover-up issue. Sprouse kept his commitment; Brown didn't. Question: If Brown could have refuted my claim of a cover-up, why didn't he come to present it before Gene Sprouse? I am appealing LJ12135's rejection.

  11. Titan's zonal winds in its lower stratosphere

    NASA Astrophysics Data System (ADS)

    Flasar, F. Michael; Schinder, Paul J.

    2016-10-01

    Titan's atmosphere near 80 km (20 mbar) marks the transition between lower altitudes, where radiative damping times are large and seasonal variations are muted, and higher higher altitudes, where the damping times are much smaller and temperatures and winds vary significantly over the year. Cassini radio occultation soundings at high northern latitudes in winter have indicated a sharp transition from a highly stable temperature profile in the lower stratosphere to a layer between 80 and 100 km where temperatures decrease with altitude. The cause of this destabilization may be associated with the enhanced infrared opacity of a cloud of organic ices. It is curious that 20 mbar is also the level where the Doppler Wind Experiment on the Huygens Probe at 10° S observed a deep minimum in the zonal wind profile. Application of the gradient wind relation to the altitude-pressure profiles obtained from the Cassini radio occultation soundings have shown that this minimum is global. More recent soundings, obtained as Titan's southern hemisphere moves toward winter, indicate that this structure persists. The cause of this peculiar behavior is not really understood, but the the deceleration of the zonal winds observed in the lower stratosphere may be caused by radiative damping of vertically propagating atmospheric waves in a region where the damping time decreases rapidly with altitude.

  12. Storms in the tropics of Titan.

    PubMed

    Schaller, E L; Roe, H G; Schneider, T; Brown, M E

    2009-08-13

    Methane clouds, lakes and most fluvial features on Saturn's moon Titan have been observed in the moist high latitudes, while the tropics have been nearly devoid of convective clouds and have shown an abundance of wind-carved surface features like dunes. The presence of small-scale channels and dry riverbeds near the equator observed by the Huygens probe at latitudes thought incapable of supporting convection (and thus strong rain) has been suggested to be due to geological seepage or other mechanisms not related to precipitation. Here we report the presence of bright, transient, tropospheric clouds in tropical latitudes. We find that the initial pulse of cloud activity generated planetary waves that instigated cloud activity at other latitudes across Titan that had been cloud-free for at least several years. These observations show that convective pulses at one latitude can trigger short-term convection at other latitudes, even those not generally considered capable of supporting convection, and may also explain the presence of methane-carved rivers and channels near the Huygens landing site.

  13. The low temperature chemistry of Titan's atmosphere

    NASA Astrophysics Data System (ADS)

    Ramírez Jiménez; , Sandra I.; Contreras Jiménez, Gastón

    2010-04-01

    In Titan's atmosphere there is a permanent transformation of its major constituents, nitrogen (N2) and methane (CH4), into more complex organic compounds. We have conducted a series of experiments in which a simulated Titan's atmosphere enriched with trace gases (C2H2, C6H6, CO) was subjected to short-period cold-plasma irradiations at liquid nitrogen temperature in a continuous flow regime. The electric plasma is produced by a high voltage generator at positive and negative polarity and at a constant power of 8.83 Watts. The identification of organic compounds formed in gas phase was performed coupling the gas chromatography and mass spectrometry techniques. They include all the hydrocarbons and nitriles already detected in the satellite's atmosphere, particularly the unsaturated and aromatic ones, and some oxygenated compounds. The energetic yield for each one of the identified compound was calculated and contrasted with results of experiments performed during the last decade in different laboratories (Cabane and Chassefière, 1995; Coll et al., 1999; Ramírez et al., 2001; Ramírez et al., 2002) finding interesting remarks.

  14. 1912: a Titanic year for mass spectrometry.

    PubMed

    Downard, Kevin M

    2012-08-01

    The 1912 sinking of the Titanic continues to capture the imagination and fascination of the general public. The year coincides with the birth of mass spectrometry that began with the cathode ray experiments performed by Joseph John (J. J.) Thomson in Cambridge. Modifications made to Thomson's cathode ray apparatus by Francis William Aston, resulted in an increase in the brightness of the positive rays that aided their detection. This led to the discovery of heavy isotopes for many of the chemical elements in the ensuing decades. As the discovery of (22) Ne was reported in 1913, another of Thomson's students was taking part in an expedition to help save future ocean liners from the fate of the Titanic. Geoffrey Ingram Taylor took part in the first ice patrol of the North Atlantic in 1913 aboard the SS Scotia to investigate the formation and position of icebergs. This article, 100 years on, describes Taylor's work and its impact on safe ocean passage across the Atlantic.

  15. Titan's Length-of-Day Variations

    NASA Astrophysics Data System (ADS)

    Folonier, Hugo Alberto; Ferraz-Mello, Sylvio

    2015-11-01

    The Cassini radar observation of Titan over several years show that the rotation period is slightly faster than the synchronous motion (Lorenz et al. 2008; Stiles et al. 2008 and 2011; Meriggiola 2012). The seasonal variation in the mean and zonal wind speed and direction in Titan’s lower troposphere causes the exchange of a substantial amount of angular momentum between the surface and the atmosphere (Tokano and Neubauer, 2005; Richard et al. 2014). The rotation variation is affected by the influence of the atmosphere when we assume that Titan is a differentiated body and the atmosphere interacts only with the outer layer.In this work, we calculate variations of Titan’s length-of-day when the body is formed by two independent rotating parts and assuming that friction occurs at the interface of them. The tides are considered using the extension of two different theories -- the Darwin tide theory and Ferraz-Mello’s creep tide theory -- to the case of one body formed by two homogeneous parts. The results are compared and their differences are discussed.

  16. Processing ISS Images of Titan's Surface

    NASA Technical Reports Server (NTRS)

    Perry, Jason; McEwen, Alfred; Fussner, Stephanie; Turtle, Elizabeth; West, Robert; Porco, Carolyn; Knowles, Ben; Dawson, Doug

    2005-01-01

    One of the primary goals of the Cassini-Huygens mission, in orbit around Saturn since July 2004, is to understand the surface and atmosphere of Titan. Surface investigations are primarily accomplished with RADAR, the Visual and Infrared Mapping Spectrometer (VIMS), and the Imaging Science Subsystem (ISS) [1]. The latter two use methane "windows", regions in Titan's reflectance spectrum where its atmosphere is most transparent, to observe the surface. For VIMS, this produces clear views of the surface near 2 and 5 microns [2]. ISS uses a narrow continuum band filter (CB3) at 938 nanometers. While these methane windows provide our best views of the surface, the images produced are not as crisp as ISS images of satellites like Dione and Iapetus [3] due to the atmosphere. Given a reasonable estimate of contrast (approx.30%), the apparent resolution of features is approximately 5 pixels due to the effects of the atmosphere and the Modulation Transfer Function of the camera [1,4]. The atmospheric haze also reduces contrast, especially with increasing emission angles [5].

  17. Low Temperature Spin Structure of Gadolinium Titanate

    NASA Astrophysics Data System (ADS)

    Javanparast, Behnam; McClarty, Paul; Gingras, Michel

    2012-02-01

    Many rare earth pyrochlore oxides exhibit exotic spin configurations at low temperatures due to frustration. The nearest neighbor coupling between spins on the corner-sharing tetrahedral network generate geometrical magnetic frustration. Among these materials, gadolinium titanate (Gd2Ti2O7) is of particular interest. Its low temperature ordered phases are not yet understood theoretically. Bulk thermal measurements such as specific heat and magnetic susceptibility measurements find two phase transitions in zero external field, in agreement with simple mean field calculations. However, recent neutron scattering experiments suggest a so-called 4-k spin structure for intermediate phase and a so called canted 4-k structure for lower temperature phase that does not agree with either mean-field theory or Monte Carlo simulation which find the 1-k state and Palmer-Chalker state respectively as the lowest free energy configuration for those phases. In our work, we study the 4-k structure in detail and present a new phase diagram for dipolar Heisenberg spins on a pyrochlore lattice, certain portions of which describe gadolinium titanate.

  18. Composition of the lakes of Titan

    NASA Astrophysics Data System (ADS)

    Mousis, O.; Cordier, D.; Lunine, J. I.; Lavvas, P.; Vuitton, V.

    2009-11-01

    Hundreds of radar-dark patches interpreted as lakes have been discovered in the north and south polar regions of Titan. We have estimated the composition of these lakes by using the direct abundance measurements from the Gas Chromatograph Mass Spectrometer (GCMS) aboard the Huygens probe and recent photochemical models based on the vertical temperature profile derived by the Huygens Atmospheric Structure Instrument (HASI). Thermodynamic equilibrium is assumed between the atmosphere and the lakes, which are also considered as nonideal solutions. We find that the main constituents of the lakes are ethane (C_2H_6) (˜ 76-79%), propane (C_3H_8) (˜ 7-8%), methane (CH_4) (˜ 5-10%), hydrogen cyanide (HCN) (˜ 2-3%), butene (C_4H_8) (˜ 1%), butane (C_4H_{10}) (˜ 1%) and acetylene (C_2H_2) (˜ 1%). The calculated composition of lakes is then substantially different from what has been expected from models elaborated prior to the exploration of Titan by the Cassini-Huygens spacecraft.

  19. TEAM – Titan Exploration Atmospheric Microprobes

    NASA Astrophysics Data System (ADS)

    Nixon, Conor; Esper, Jaime; Aslam, Shahid; Quilligan, Gerald

    2016-10-01

    The astrobiological potential of Titan's surface hydrocarbon liquids and probable interior water ocean has led to its inclusion as a destination in NASA's "Ocean Worlds" initiative, and near-term investigation of these regions is a high-level scientific goal. TEAM is a novel initiative to investigate the lake and sea environs using multiple dropsondes –scientific probes derived from an existing cubesat bus architecture (CAPE – the Cubesat Application for Planetary Exploration) developed at NASA GSFC. Each 3U probe will parachute to the surface, making atmospheric structure and composition measurements during the descent, and photographing the surface – land, shoreline and seas - in detail. TEAM probes offer a low-cost, high-return means to explore multiple areas on Titan, yielding crucial data about the condensing chemicals, haze and cloud layers, winds, and surface features of the lakes and seas. These microprobes may be included on a near-term New Frontiers class mission to the Saturn system as additional payload, bringing increased scientific return and conducting reconnaissance for future landing zones. In this presentation we describe the probe architecture, baseline payload, flight profile and the unique engineering and science data that can be returned.

  20. Illness/injury pattern complex 40 (Titan)

    NASA Technical Reports Server (NTRS)

    Blasdell, Sharon

    1993-01-01

    On July 31, 1991, EG&G Medical began providing medical support at the Titan Area Clinic (TAC). The hours of operation are 0700-2300, Monday through Friday, with Emergency Medical Services (EMS) provided 24-hours a day, seven days a week. The TAC consists of a 10 x 10 ft section of a trailer that also houses Bechtel Safety. Supplies consisted of an examining table, an eye wash chair, first aid equipment, over-the-counter medications, spine boards, a portable rescuscitator, etc. All of the nurses are Advanced Cardiac Life Support (ACLS) certified. Although the Titan Area Clinic is strictly a first-aid station with no ACLS facilities on-site, it is staffed with an Occupational Health Nurse with ACLS certification. If ACLS or additional help is needed, the nurse activates EMS by dialing 911. The nurse responds to any medical problems or emergencies on the complex, but activates EMS prior to leaving the TAC. A Bechtel Safety Representative accompanies the nurse to the site and assists as needed. Other aspects of the complex and its functions are presented.