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Abstracts received before 23/5/2006

Models of planet formation with migration and disk evolution - Monte-Carlo approach.

Alibert, Yann Mordasini, Christoph Benz, Willy Naef, Dominique Physikalisches Institut, University of Bern CH-3012 Bern - Switzerland European Southern Observatory, Alonso de Cordova 3107, Casilla 19001 santiago 19, Chile

presented by: Alibert, Yann email-yann.alibert@space.unibe.ch, phone-+41 31 631 44 27, fax-+41 31 631 44 05

We present Monte-Carlo calculations based on extended core-accretion planet formation models taking into account disk structure and evolution and migration of the protoplanet. These models lead to giant planet formation timescales compatible with disk lifetimes.

For different initial conditions, we calculate the evolution of a disk and an embryo that may form a giant planet. The initial conditions are in particular the disk mass, disk lifetime and metallicity of the system.

Using observed distributions for these initial conditions, and taking into account the observational bias introduced by radial velocity surveys, we will compare in a statistical way the results of our models and the population of know extrasolar planets.

Río Tinto as an anlogue of martian mineralogy

Amils, R., Fernández-Remolar, D., Gómez, F., Rodríguez, N. Centro de Astrobiología, INTA, carretera de Ajalvir, km 4, 28850 Torrejón de Ardoz, Madrid Spain

presented by: Amils, R. email-ramils@cbm.uam.es, phone-34/91/4978078, fax-34/91/4978087

Río Tinto is an extreme acidic river that is the result of the action of subsurface geomicrobiology on the complex sulfides of the Iberian Pyritic Belt (MARTE project). The Tinto ecosystem is controlled by iron. Different iron minerals can be found in the Tinto basin as products of this geomicrobiological activity. The higher solubility of sulfates over iron hydroxides and the acidic nature of ferric iron promotes a gradual enrichment in sulfates along the river. The geobiological properties of this extant iron world raises the question of its feasibility both during our Archaean when ocean iron concentration several orders of magnitude higher than nowadays, or on Mars, in light of the latest reports from the ongoing missions.

Technology Challenges and Mission Architecture Options for the In-Situ Exploration of Icy Satellites

Tibor S. Balint, James A. Cutts,   Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, M/S 301-170U, Pasadena, California, 91109

Understanding the composition, geology, environment, dynamics and astrobiology potential of icy satellites could elucidate us about the formation of the solar system and its potential to harbor life. Consequently, in the Solar System Exploration Decadal Survey (2002) the National Research Council (NRC) identified the exploration of Europa, Jupiter's icy satellite, as the highest priority science objective to be addressed through the flagship class mission category. According to NASA's Solar System Exploration Roadmap (2006), follow up missions could target other icy moons, such as Saturn's Titan, and Neptune's Triton. Furthermore, based on recent discoveries by the Cassini orbiter, Enceladus also became a significant target of interest. In-situ exploration of these moons is highly desirable, in order to complement and validate orbital remote sensing measurements. In this paper we discuss mission architecture options and technology challenges for icy body landers, with a special focus on three small Europa lander concepts and on a Triton lander concept. In the same context we also address two other icy moons, Enceladus and Titan. The mass allocation for this type of landers is driven by mission architecture and technology considerations. We demonstrate that in all cases a significant fraction  potentially well over 50%  of the entry mass is required to slow down and to land the spacecraft. Europa, Triton and Enceladus are airless bodies, where a lander must remove most or all of its excess velocity through propulsive means. We address various landing methods through a comparison between soft and hard landers and impactors. On Titan, however, the atmosphere could be utilized for an aeroassist maneuver to remove most of the entry velocity, by employing an aeroshell and parachutes. We also discuss the potentially available mass fractions for strawman science payloads  expected in the range of 2.5% to 10%. Extreme environments at these destinations have a significant impact on the mission and technology trade space. Low temperature electronics, high radiation tolerant electronics and radioisotope power systems (RPS) could extend mission lifetime; while advanced propellants could increase payload mass fraction. We address power system trades between batteries and RPSs as a function of in-situ mission duration. Additional challenges for a landed mission will be also discussed, which could include potential contamination of the landing site by the propulsion system; planetary protection issues; terrain uncertainty during and after landing; communication constraints between the lander and orbiter or Earth; and the design of a suitable sampling mechanism. Consequently, in this paper we provide an overview of mission architecture and technology trade space options and challenges, which could enable potential future mass limited landers to mitigate the encountered extreme environments, while exploring these icy satellites of our outer solar system in line with the Vision for Space Exploration.

A Terrestrial analogue to Europa's salty ocean: the Tirez lake (geological and geochemical aspects)

Olga Prieto Ballesteros Centro de Astrobiologia

presented by: Olga Prieto Ballesteros email-prietobo@inta.es, phone-+34 91 5206429, fax-+34 91 5201074

Based on the comparison of its hydrogeochemistry with the geochemical features of the alteration mineralogy of meteoritic precursors and with Galileo`s NIMS data, Tirez Lake (Spain) is proposed as a terrestrial analogue of the Europa's ocean. Hydrogeochemical and mineralogical analyses showed that Tirez waters corresponded to Mg-Na-SO4-Cl brines with epsomite, hexahydrite and halite as end members. Frozen Tirez brines were analyzed by FTIR, providing similar spectra to the Galileo spectral data. Calorimetric measurements of Tírez brines showed pathways and phase metastability for magnesium sulfate and sodium chloride crystallization which may aid in understanding the processes involved in the formation of Europa's icy crust. Biological aspects of Tirez lake will be described in Gomez F. presentation (this issue)

The atmosphere of an exoplanet

Isabelle Baraffe, ENS, Lyon, France

presented by: Isabelle Baraffe email-ibaraffe@ens-lyon.fr, phone-+33 4 72 72 87 04, fax-+33 4 72 72 87 87

The number of exoplanets newly discovered increases rapidly with time. Those detections are, however, still indirect, via radial velocity surveys and photometric transits, and still very little is known about their atmospheric properties. Despite this lack of direct observations, many efforts are devoted to the modelling of exo-planet atmospheres. I will review the current status of giant planet atmosphere models, and describe their main properties. I will also describe the properties of planets orbiting their parent star at close orbital distances. The former undergo irradiation effects from their parent star and eventually evaporation effects. Both processes can severely affect the properties of close-in planets, in terms of atmosphere structure, emitted flux and evolution.

Global Spectral Diversity of Titan's Surface

Jason W. Barnes, Robert H. Brown, Bonnie J. Buratti, Christophe Sotin, Lawrence Solderblom, Kevin Baines, Roger Clark, and Phil Nicholson University of Arizona / LPL, JPL, Universite de Nantes, USGS, Cornell University

presented by: Jason W. Barnes email-jbarnes@c3po.lpl.arizona.edu, phone-(520)327-8483, fax-(520)621-4933

Titan shows a variegated surface to the Cassini orbiter in near-infrared reflection. The equatorial regions are a vast, dark dunefield intersperced with brighter material including unique Xanadu; the mid-latitudes are bright, but spectrally distinct from the equatorial brightlands; and the south pole is again a mixture of bright and dark, with the different dark material than that near the equator. Two distinct 5-micron-bright areas adorn the leading hemisphere. We present color global mapping of Titan and spectral unit maps of Titan's surface generated using principal components and cluster analyses. We discuss these results in the context of returns from Huygens and RADAR to paint a global picture of Titan's state and evolution.

TNO surface properties

M.Antonietta Barucci LESIA Observatoire de Paris

presented by: M.A. Barucci email-antonella.barucci@obspm.fr, phone-33.145077775, fax-33.145077110

Trans-Neptunian objects and Centaurs contain the least processed material accessible to direct investigation and they can provide important clues on the processes that were operating in the protoplanetary nebula. The study of these objects can help in understanding the accretion processes which governed the planetary formation, as well as those of other dust star disks.

Studies of the physical and chemical properties of these icy bodies are still limited by the faintness of these objects, even if observed with the worldwide largest telescopes. Recent observations in visible photometry have provided B, V, R and I high quality colors for more than 130 objects. The color diversity is now a reality in the TNOs population. Relevant statistical analysis have been performed and all possible correlations between optical colors and orbital parameters have been analyzed. A taxonomy scheme based on multivariate statistical analysis of a subsample described by the 4 color indices (B-V, V-R, V-I and V-J) has been obtained. A tentative interpretation of the obtained groups in terms of surface characteristics is given.

Visible and infrared spectra are available for about 30 objects. The wavelength region ranging 0.4 - 2.3 microns encompass diagnostic spectral features to investigate on organic compounds, minerals and ices present on the surface of the TNOs. While some show no diagnostic spectral bands, others have surface deposits of ices of H20, CH4, and N2 sharing these properties with Pluto and Triton. The investigation of the surface variation can be diagnostic of possible composition diversity and/or different evolution with different physical processes affecting the surface.

The state of art on the knowledge of the surface properties and composition of the population will be presented, analyzed and interpreted. Possible surface alteration will be investigate and discussed.

Saturnian stream particles: origin and dynamics inside Saturn's magnetosphere

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Uwe Beckmann, Sascha Kempf, Ralf Srama, Georg Moragas-Klostermeyer,Stefan Helfert, Eberhard Grün Max-Planck-Institut für Kernphysik

presented by: Uwe Beckmann email-Uwe.Beckmann@mpi-hd.mpg.de, phone-+49-6221-516-563, fax-

In 2004, the Cosmic Dust Analyzer (CDA) onboard the spacecraft Cassini detected dust streams of nanometer-sized particles up to 1 AU (Astronomical Unit » 1.5 ·1011m) away from Saturn.

Backtracking the particles path showed that their origin lay inside the Saturnian system.

The creation process of these dust streams is understood: tiny grains are charged up by Saturn's surrounding plasma and get accelerated inside Saturn's magnetosphere. Due to their large charge to mass ratio, the particles reach escape velocity and leave the Saturnian system. But the particles' sources are still unknown.

Additionally, this particle population is difficult to detect by CDA inside Saturn's magnetosphere. The dominant part of the dust measurements are micron-sized dust particles, which build the E ring, Saturn's largest ring.

Here we present a model calculation of tiny particles inside Saturn's magnetosphere. First estimates of their sources and their differences to bounded dust particles are given.

Mars: History and past climate from recent space observations

Jean-Pierre Bibring, and the OMEGA team Institut d'Astrophysique Spatiale (IAS)

presented by: Jean-Pierre Bibring email-bibring@ias.u-psud.fr, phone-+33 1 6985 8686, fax-+33 1 6985 8606

The present Mars missions, coupling in situ measurements in two selected sites by the NASA rovers, to orbital coverage, in particular through the ESA/Mars Express, offer an in-depth revisiting of the long-term Mars History, with a special emphasis on the role water played. We will discuss the most recent discoveries, with relevance to the possibility for Mars to have hosted habitats in its early times.

Space Weather at 9P/Tempel 1: Chandra observations during the Deep Impact campaign

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D. Bodewits (1), C.M. Lisse (2), D. J. Christian (3), S. J. Wolk (4), K. Dennerl (5), T.H. Zurbuchen (6), K.C. Hansen (6), R. Hoekstra (1), M. R. Combi (6). T. Makinen (7), P. Schultz (8), H.A. Weaver (2) (1) KVI atomic physics, Rijksuniversiteit Groningen; (2) Planetary Exploration Group, Space Department Johns Hopkins University, Applied Physics Laboratory; (3)Queens University Belfast, Department of Pure and Applied Physics; (4)Chandra X-Ray Observatory Center, Harvard-Smithsonian Center for Astrophysics; (5) Max-Planck-Institut für extraterrestrische Physik; (6) The University of Michigan, Department of Atmospheric, Oceanic and Space Sciences; (7) Finnish Meteorological Institute, Space Research; (8) Department of Geological Sciences, Brown University

presented by: D. Bodewits, email-bodewits@kvi.nl, phone-+31-50-363-5195, fax-+31-50-363-4003

On July 4, 2005 NASA's Deep Impact sent a 375 kg impactor into the nucleus of comet 9P/Tempel 1. We report here on the results of the Chandra observations of the Deep Impact encounter. Comets emit X-rays when highly charged ions from the solar wind charge exchange with its neutral coma. Because of the comet's low outgassing rate it was collisionally thin to charge exchange. Freshly released gas should therefore directly increase the emission measure, allowing Chandra to detect gas created by the impact. The nearly 30 day time span of our observations sampled several severe changes in the solar wind and outbursts in the comet's activity, which can be clearly identified in the observed X-ray emission morphology, spectra and long term light curve.

Charge Exchange Emission from Solar Wind Ions

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D. Bodewits (1), A. G. G. M. Tielens(2), R. Hoekstra (1) (1) KVI atomic physics, Groningen University; (2) Kapteyn Institute, Groningen University

presented by: D. Bodewits email-bodewits@kvi.nl, phone-+31-50-363 5195, fax-+31-50 363 4003

Charge exchange emission in (soft) X-ray results from the interaction between the solar wind and comets, planets and the ISM. Depending strongly on velocity and target species, this emission can be regarded as a fingerprint of the underlying interaction. This can open a new window on local plasma conditions, thusfar only accessible by space exploration - given sufficient knowledge is available about charge exchange. We studied these reactions in the laboratory with special emphasis on collisions between He2+ and gasses characteristic for cometary and planetary atmospheres. The data are used to demonstrate the diagnostics of charge exchange emission by analyzing EUVE observations of comets Hyakutake and Hale-Bopp in terms of solar wind and coma quantities.

The Juno Mission

Scott J. Bolton and the Juno Team Southwest Research Institute

presented by: Scott J. Bolton email-sbolton@swri.edu, phone-210 522 3851, fax-210 543 0052

The Juno mission, currently in Phase B, was selected by NASA to be the second mission in the New Frontiers Program. The overarching scientific goal of the Juno mission is to understand the origin and evolution of Jupiter. As the archetype of giant planets, Jupiter can provide the knowledge we need to understand the origin of our own solar system and the planetary systems being discovered around other stars. Juno's investigation of Jupiter focuses on four themes: Origin, Interior Structure, Atmospheric Composition and Dynamics, and the Polar Magnetosphere.

The scientific measurements include global maps of the gravity and magnetic fields, microwave radiometry of Jupiter's deep atmosphere and fields and particles measurements of Jupiter's polar magnetosphere. Juno's 32 polar orbits extensively sample Jupiter's full range of latitudes and longitudes. High sensitivity radiometric measurements yield a 3-dimensional view of Jupiter's deep atmosphere (down to >100 bars) and will be used to infer the global abundance of water, and to investigate the deep atmosphere's complex meteorology. Determining the Jovian water abundance permits discrimination between various scenarios of the formation of Jupiter. The gravity data constrain the planet's interior rotation, core size and interior structure. The magnetic field measurements investigate how the interior dynamo works and examine the depth of generation of Jupiter's powerful magnetic field. Fields and particles measurements as well as UV polar images investigate Jupiter's auroral physi! cs to determine what drives Jupiter's remarkable northern and southern lights.

An overview of the mission and science objectives will be presented.

Study of the Io footprint short timescale variability

B. Bonfond, J.-C. Gérard, D. Grodent Laboratoire de Physique Atmosphérique et Planétaire - Université de Liège (Belgium)

presented by: Bertrand Bonfond email-B.Bonfond@ulg.ac.be, phone-+ 32 (0) 4 366 97 72, fax-+ 32 (0) 4 366 97 11

The electromagnetic interaction between Io and Jupiter leads to single or multiple auroral UV spots in both jovian hemispheres. This study concentrates on short timescale ( 1 min) morphological changes of the footprints. In order to achieve a sufficient time resolution, we use the time-tag mode of the HST/STIS instrument. This allows us to account for the spots blurring due to the rapid evolution of the jovian magnetic field lines. In addition to the spots motion, our analysis focuses on the spots brightness variations and on the correlation between these variations. The characterisation of the parameters herein gives rise to both clues and new questions on the mechanisms that induce the precipitation of energetic electrons.

Structures in the coma of COMET C/NEAT (2001 Q4): analysis and Monte Carlo modelling

Galin Borisov and Tanyu Bonev,   Institute of Astronomy, Bulgarian Academy of Sciences

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Comet C/NEAT (2001 Q4) was observed in three consecutive nights in May 2004 (19th, 20th and 21th) with the 2m Ritchey-Chretien-Coude telescope and the 2-Channel Focal Reducer at the Bulgarian National Astronomical Observatory -Rzhen. Narrow-band filters were used, centered on the blue and red comets' continuum at 443 nm and 642 nm, respectively. The images were calibrated to intensities using spectrophotometric standard star observed at the same airmass. The raw images show irregularity of the dust coma in the direction to the Sun. After applying a numerical filter jet-like structures are visible. For the description of these features a Monte-Carlo model, based on Finson-Probstein theory for dust particles dynamics, is developed. The size of the active region, its coordinates on the nucleus surface, and the range of the dust particles' sizes were found by trial and error. Fixed values of the particle size distribution, the rotational period and the orientation of the rotation axis were adopted. The contribution of the structures to the total intensity of the dust coma is 4-5size of the active region. This suggests that the source region of the observed structures is 10 times more active than the remaining nucleus surface. The images obtained at both continuum wavelengths were used to produce color maps of the dust coma. The color of the structure does not deviate strongly from the color of the ambient dust coma.

Polar Caps on Titan?

Robert H. Brown University of Arizona, Dept. of Planetary Sciences

presented by: R. H. Brown email-rhb@lpl.arizona.edu, phone-520-628-9907, fax-

It is now quite clear that there are no large expanses of liquid organics on Titan detectable by Cassini's optical instruments. Unless photochemical models are quite wrong, it is difficult to account for the absence of the predicted simple organics. A possible way out of the conundrum is that some fraction of the simple organics on Titan is tied up in polar ice deposits consisting of ethane mixed with enough other organics to raise its freezing point enough to keep it solid over some range of latitudes on Titan. To investigate this hypothesis, I have constructed a simple model of polar cap formation on Titan that employs 1-dimensional, glacial-flow, combined with assumptions about the extent and rate of solid precipitation on Titan. The calculations will be presented and conclusions drawn as to the total volatile inventory and latitudinal extent of Titan's hypothetical polar caps.

High resolution spectroscopy with SARG at TNG (La Palma) before and after the DEEP IMPACT event

M.T. Capria (1), G. Cremonese (2), M.C. De Sanctis (1), E. Epifani (3), J. Licandro (4) (1) INAF-IASF Rome Italy, (2) INAF-OAPD Padua Italy, (3) INAF-OAC Naples Italy, (4) INGT/IAC Tenerife Spain

presented by: M.T. Capria email-mariateresa.capria@iasf-roma.inaf.it, phone-+39 06 4993 4452, fax-

On July 4, 2005 the NASA spacecraft Deep Impact delivered an impactor on the comet 9P/Tempel 1 to study the material ejected from the nucleus. A worldwide observation campaign accompanied the mission, to characterize the activity of Tempel 1 before and after the impact. At La Palma (Canary Islands), the comet was observed from July 2 to July 9 using the echelle spectrograph SARG on the Telescopio Nazionale Galileo (TNG). 15 spectra have been obtained in the spectral range 4620-7920 Å with a resolving power R=29000. Most of the lines found in the spectra can be attributed to C2, NH2 and CN; the atomic oxygen lines, both the green line at 5577 Å and the red doublet at 6300 and 6364 Å are clearly visible in every spectrum. The intensity ratio between the green line and the sum of the red lines, indicative of the parent of these lines, has been computed for most of the spectra and seems to point to water. Only the ratio computed on the spectra taken few hours after the impact has a slightly different value.

The Search for Power in the Saturnian System

J. Castillo, D. Matson, T. Johnson, J. Lunine Jet Propulsion Laboratory California Institute of Technology Pasadena CA USA, Lunar and Planetary Laboratory Tucson Arizona USA / ITA-ISFI Roma Italy

presented by: Julie Castillo email-julie.c.castillo@jpl.nasa.gov, phone-1 818 354 0019, fax-

New spacecraft data, material parameters and better heat transfer theories, yield outer planet satellite interiors colder than previously thought. While there are observations indicating that these satellites are very cold (e.g., heavily cratered surfaces, non-hydrostatic shapes), there are also numerous indications of endogenic activity: tidally driven dynamical evolution (e.g., Iapetus' synchronous state), geology (e.g., Enceladus' geysers), and differentiated interiors that require the production of a large amount of heat. Existing models are not favorable for developing tidal dissipation as a driver for endogenic activity and dynamical evolution. We show new models that include (1) initial porosity;, (2) short-lived radionuclides that can melt most or all of the ice and can make the interior dissipative for enabling tidally driven processes. This work was carried out by the Jet Propulsion Laboratory, California Institute of Technology, under NASA contract.

Recent Results, New Approaches, Hypotheses, Riddles, and "Way to Go?" in the Geophysics of Outer Planet Satellites

D. Matson, J. Castillo, T. Johnson, J. Lunine, C. Sotin Jet Propulsion Laboratory California Institute of Technology Pasadena CA USA, Lunar and Planetary Laboratory Tucson Arizona USA / ITA-ISFI Roma Italy, LPGN Universite de Nantes France

presented by: Dennis Matson email-julie.c.castillo@jpl.nasa.gov, phone-1 818 354 2253, fax-

Since the Voyager missions, Galileo and Cassini-Huygens have explored in detail the satellite systems of Jupiter and Saturn, respectively. Laboratory experiments have improved our knowledge of material properties relevant to the satellites. Advances in geophysical modeling have provided new views of the interior, exterior, and orbital evolution. We present new approaches that allow to understand how small satellites can be significantly more geologically-dynamically active than previously thought (e.g., Enceladus' geysers); and to solve long-standing riddles (e.g., Iapetus' synchronous rotation). These new models involve the presence in the early outer Solar system of short-lived radiogenic species. We discuss the implications of these new results, e.g., fine-scale radiochronometry of satellites and constraints on the environment in which they formed and evolved. This work was carried out by the Jet Propulsion Laboratory, California Institute of Technology, under NASA contract.

Origin of the atmospheres of the terrestrial planets

Chassefière Eric Service d'Aéronomie/ Institut Pierre Simon Laplace

presented by: Chassefière Eric email-eric.chassefiere@aero.jussieu.fr, phone-33 1 44 27 37 53, fax-33 1 44 27 37 76

The atmospheres of the three terrestrial planets (Venus, Earth, Mars) are thought to have evolved from a relatively similar initial state to the present, extremely different, conditions. Whereas Mars lost most of its amosphere and evolved toward desertification, Venus probably undergone a runaway greenhouse resulting in a massive atmosphere and a high surface temperature. The absence of liquid water on Mars and Venus, their one-plate tectonic regime, the lack of an intrinsic magnetic field protecting them from solar wind erosion, make them different from Earth. Understanding why they evolved differently, and why Earth didn't follow these two extreme paths, is a major goal of comparative planetology. Different aspects of atmospheric evolution, coupled to interior evolution, will be presented, and replaced in the context of space exploration.

Planet-planet scattering in systems with multiple Jupiters

S. Chatterjee, F. A. Rasio Northwestern University, Northwestern University

presented by: S. Chatterjee email-s-chatterjee@northwestern.edu, phone-1-847-491-4661, fax-1-847-491-3135

We study long-term instabilities and planet-planet scattering in a system with three giant planets around a central star using numerical experiments. We characterize the growth timescale of instability as a function of the initial orbital configuration. We obtain the final stable configurations and determine their statistical properties from large numbers of integrations. We discuss strong planet-planet scattering as a possible mechanism for producing both highly eccentric orbits and "Hot Jupiters" in the observed extrasolar planet population.

Metallicity evolution in young stars

Carolina Chavero, Ramiro de la Reza Observatório Nacional-Rio de Janeiro

presented by: Carolina Chavero email-carolina@on.br, phone-55 21 3878 9223, fax-55 21 2580 6041

The investigation of the physical mechanisms explaining the observed planet-star metallicity correlation is of particular interest today. Nevertheless,we don´t have a clear idea for this mechanism and we can express this problem this way:is high metallicity the cause of planets or planets the cause of high metallicity ? We investigate the behavior of the metallicity of young coeval associations with different ages in relation with the convective layer´s size of the stellar members. We performed a similar analysis for old main sequence field stars. This will maybe test the possibility of explaining the know observed strong correlation of stars with planets with larger metallicity by means injection of planetesimals during the early stage of evolution.

On the Scale Problem in Planetary Exploration and How it can Distort our Views of Mars

Benton C. Clark Lockheed Martin Space Exploration Systems, Denver, CO, USA.

presented by: Clark email-benton.c.clark@LMCO.com, phone-01-303-971-9007, fax-01-303-971-2390

In Earth sciences, observations from orbit often benefit from "ground truth," but occur only rarely for planetary explorations. Fortunately, orbiter ground-track pixel sizes are decreasing while spectral band content is increasing. Landers are becoming rovers, expanding their vistas by orders of magnitude. With these advances, the challenges of scale are becoming more apparent. The discovery of as many different classes of rock types by MER Spirit rover in a transect across one topographic feature (Husband Hill, area   4 km2) as the total number of compositional units mapped by orbiters over the entire planet (100 million km2 in area) indicates the fundamental dilemma for exploring a complex planet. Aqueous history of Meridiani Planum is revealed by "microscopic imaging" (100 µm pixel size) of bedding patterns. The scale gap inhibits a secure understanding of Mars.

Planetary Magnetic Fields: from Plate Tectonics on Mars to the Geysers of Enceladus

J. E. P. Connerney,  NASA GSFC

presented by: Jack Connerney email-Jack.Connerney@nasa.gov, phone-301 286 5884, fax-301 286 1433

Magnetism is the essential tool of geophysics. An active dynamo tells us about the composition and state of a planet's (satellite's) interior and how it evolved. Crustal remanence gives us a magnetic record of times past, as illustrated by the striped pattern of anomalies associated with sea floor spreading (on Earth and Mars)in the presence of a reversing dynamo. I argue that the Mars Global Surveyor (MGS) mapping observations can be interpreted in the context of plate tectonics. From Mars we travel to the Saturn system, to rings sculpted by an electromagnetic erosion process that to this very day delivers water from the geysers of Enceladus to Saturn's atmosphere.

The Formation of regular satellites

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Angioletta Coradini(1) and Gianfranco Magni(2) (1)IFSI- INAF- Rome (2)IASF- INAF-Rome

presented by: angioletta Coradini email-angioletta.coradini@ifsi-roma.inaf.it, phone-+39 06 4993 4184, fax-+39 06 20 66 01 88

In this presentation we will review the satellite systems structure and we will try to describe what are the main processes leading to their formation. The satellite formation process cannot be studied independently from will the formation of the central body, and therefore we will describe it in the context of the giant planet formation. There are 2 main groups of satellites: 1- Major Prograde Satellites of Jupiter, Saturn, and Uranus. In this case the role of the central object is extremely important, in fact as the gas giants formed, the pulled in gas and dust due to their gravitational attraction. This material collapsed into a disk in much the same way that the solar nebula did. The inner portion of these disks were possibly warmer due to the heat of the forming planet, so we see similar gradients in composition (rock/ice mix) to those in the solar system as a whole. The process of disk formation and the disk characteristics will be discussed. It will be shown that satellites can be formed in this kind of disk. 2. Captured Satellites Many small outer moons of the gas giants are captured. Aso in this case the thermodinamical characteristics of the gas swirling about the central body could be relevant. The probability of gas capture will be also discussed.

Combining radial velocities and dynamical study to constrain extrasolar planets orbital elements

J. Couetdic, J. Laskar, A.C.M. Correia IMCCE Departamento de Fisica da Universidade de Aveiro

presented by: J. Couetdic email-couetdic@imcce.fr, phone-(+33)1 40 51 20 24, fax-(33)1 40 51 20 55

152 extrasolar planetary systems have now been detected by radial velocity(RV), 18 of which are multiple systems. Because of the planets proximity, and large masses and eccentricities (eg. HD202206, GJ876, HD82943), these multiple systems show large chaotic regions and, due to the uncertainties in the observations and in the dynamical models, numerical fits from RV can be largely unstable. On the other hand, stable regions can exist nearby the solution with optimal fit, as for example, in presence of a resonant island. The stable resonant solution, which can be found through dynamical studies and frequency map analysis, should then be preferred to the solution of optimal fit. Combining RV and frequency analysis, we can thus provide stable fits for planetary systems, and also look for possible limits on inclination and masses.

Titan's chemical composition in the stratosphere

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Athena Coustenis LESIA, Paris-Meudon Observatory

presented by: Athena Coustenis email-athena.coustenis@obspm.fr, phone-+ 331 45077720, fax-+ 331 45077469

Investigations of Titan's atmospheric composition in the past decade include measurements by ISO (detection of the water vapor in Titan's atmosphere and description of the chemical composition as a disk-average). More recently, data recorded by Cassini/CIRS allow the study of several molecular signatures: hydrocarbons, nitriles and CO2. A firm detection of benzene (C6H6) was provided by CIRS at 674 cm-1, as well as the abundances of the trace constituents and some of their isotopes in Titan's stratosphere. The D/H ratio on Titan was determined from the CH3D band at 8.6 micron to be 1.25 ±0.2 ×10-4. Information is retrieved on the meridional variations of the trace constituents and tied to predictions by dynamical-photochemical models.

Diversity of comets: the two "reservoirs".

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Jacques Crovisier Observatoire de Meudon

presented by: email-jacques.crovisier@obspm.fr, phone-0145077599, fax-0145077939

Traditionally, comets are suspected to come from two "reservoirs": the Oort cloud and the Kuiper belt. The two kinds of comets formed at different places in the primitive Solar System and experienced different orbital evolutions. One can thus expect different chemical and physical properties. I will review which differences are effectively observed or expected: chemical and isotopic compositions, spin temperatures, dust particle properties, nucleus surface properties... The difficulty of such a study is that long-period comets from the Oort cloud are better known, from Earth-based observations, than the weak short-period comets from the Kuiper belt. On the other hand, only the latter are easily accessed by space missions.

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Prebiotic chemistry: the astronomer's point of view

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D. Despois Observatoire de Bordeaux OASU/L3AB

presented by: D. Despois email-despois@obs.u-bordeaux1.fr, phone-05-57-77-61-59, fax-05-57-77-61-10

Comets and asteroids are rich in complex molecules inherited from the parent interstellar cloud, synthesized in the solar nebula, or produced in the body itself. These molecules may have contributed, together with chemical synthesis in the early atmosphere and ocean, to the initial stock of prebiotic molecules from which Life has started. To precise what has been their exact role is an important question for astrobiology, and a source of challenges for astronomers, planetary scientists and chemists. We will present the concept of prebiotic molecule, the nature and possible origin of the organic molecules present in Solar system small bodies and in the Interstellar medium, the questions posed by a quantitative estimate, and some examples of progress we may expect in the future.

Models of the protoplanetary disk

C. Dominik Sterrenkundig Institut Änton Pannekoek" Univeresity of Amsterdam

presented by: C. Dominik email-dominik@science.uva.nl, phone-+31 20 525 7477, fax-

I will summarize the results of recent modelling of dust growth and settling in protoplanetary disks. For the first time now, such calculations have been coupled with full radiative transfer to show the observational effects of dust evolution in disks. These calculations show how dust coagulation leads to a fast depletion of small grains in the solar nebula, with severe consequences for the structure and appearance of the solar nebula. I will also show results of modelling the emission of the H2D+ molecule, a recently discovered tracer of cold gas and ionization in disks that may become a major tool in the future for tracing the gas component in protoplanetary disks. In this way it will finaly be possible to study the evolution of both gas and dust in disks.

Discovery of a Dynamic Atmosphere at Enceladus from Cassini Magnetometer Observations

M. K. Dougherty1, K. K. Khuarana2, F. M. Neubauer3, C. T. Russell2, J. Saur3, J. S. Leisner2 and M. E. Burton4 1Imperial College, London, SW7 2AZ, UK 2UCLA, Los Angeles, CA 90025, USA 3Koln University, 50923 Koln, Germany 4JPL, Pasadena, CA 91109, USA

presented by: Michele Dougherty email-m.dougherty@imperial.ac.uk, phone-442075947757, fax-442075947772

Cassini magnetometer observations from three targeted flybys of Saturn's icy moon Enceladus have revealed the existence of a dynamic atmosphere. This unexpected detection was originally made on a distant flyby and was subsequently confirmed on two follow-on flybys one of which was very close, at a distance of 173km from the surface of the moon. The magnetic field observations from all three flybys will be described as well as their interpretation. The observations from the second and third flybys are consistent with an atmospheric plume concentrated near Enceladus's south pole.


Dubinin E., M. Fraenz, J. Woch, E. Roussos (1), S. Barabash, R. Lundin (2), D. Winningham (3)  (1) Max-Planck Institute of Solar System Study, Katlenburg-Lindau, Germany, (2) Swedish Institute of Space Physics, Kiruna, Sweden (3) Southwest Research Institute, San-Antonio, USA

presented by: Dubinin E. email-dubinin@mps.mpg.de, phone-+49 5556 979 129, fax-+49 5556 979 240

Solar wind induced escape is one of the effective mechanisms responsible for atmospheric and ionospheric losses on Mars. ASPERA-3 observations carried out on the MEX spacecraft reveal the efficient extraction and energization of planetary ions. Planetary ions (O+, O2+, CO2+) gain energy of several keV on a distance of several thousands km from the planet. It is found that processes of ion extraction and penetration of solar wind plasma into the Martian magnetosphere are closely related. Morphology of ion fluxes, role of crustal fields and mechanisms of extractions are discussed.

Mineralogical correlation between HED meteorites and V-type asteroids

Duffard, René (1) and Lazzaro, Daniela (2) (1) Max Planck Institute for Solar System Research, Germany. (2) Observatório Nacional, Brazil

presented by: Duffard email-duffard@mps.mpg.de, lazzaro@on.br, phone-+49 5556 979464, fax-

The correlation between specific meteorites and asteroids is a long-standing problem. The best-known correlation seems to be the HEDVesta, although several problems still remain to be solved. A number of small asteroids exist with the same spectral characteristics as (4) Vesta, and are taxonomically classified as V-type, as Vesta. These small asteroids are mostly found in the region near Vesta, but some are also in near-Earth orbits, and one is in the outer part of the main belt. The purpose of this work is try to determine if the HED meteorites found on Earth and the small V-type asteroids are all genetically linked to Vesta through the comparative study of their mineralogy. We report the spectral reflectance analysis, 0.4-2.5 microns, of 47 basaltic achondrite meteorites and 22 V-type asteroids trying to associate spectral properties with mineralogy. The meteorite spectra are from 25 eucrites, 13 howardites and 9 diogenites, taken from the RELAB database. On the other han! d, the spectra of 18 main belt asteroids and 4 NEOS were observed in different instruments/telescopes. We used the Modified Gaussian Model to fit the spectra to a serie of overlapping, modified gaussian absorptions. The fitted individual bands are validated against established laboratory calibrations. With spectral resolution extending to the near-infrared, we are able to resolve the presence of both high-calcium pyroxene (HCP) and low-calcium pyroxene (LCP) and, thus, use the HCP/(HCP+LCP) ratios to remotely trace igneous processing on asteroids. A search of this mineral provides a useful probe of differentiation.The high HCP/(HCP+LCP) ratios found require extensive differentiation of these asteroids and/or their primordial parent body. The degree of melting obtained for the eucrites, using the former ratio, is comparable with that obtained for all the V-type asteroids here analyzed, suggesting a comparable geologic history.

Vesta Mineralogy with the Framing Camera onboard DAWN

Duffard, René. Nathues, A. Keller, H.U. Max Planck Institute for Solar System Research

presented by: Duffard, R. email-duffard@mps.mpg.de, phone-[+49] 5556 979 464, fax-[+49] 5556 979 240

Reflectance spectra of HED meteorites have been convolved with the response curve of the framing camera (FC) filters to obtain the expected response of the camera to the surface material of Vesta. Several spectral parameters were analyzed to obtain mineralogical information. Two framing cameras (FC) onboard the DAWN mission, designed and built by the MPI for Solar System Research in co-operation with DLR Berlin and IDA Braunschweig will provide images of the surface of asteroids (4) Vesta and (1) Ceres. The field of view of 5& # 9702;×5& # 9702; is imaged onto a frame-transfer CCD with 1024×1024 sensitive pixels. The FC will provide a high spatial resolution images of the surface of Vesta in 8 filter, one clear and 7 band pass filters in the visible/NIR range of the spectrum (430, 540, 650, 750, 830, 920 and 980 nm).

A study of the Martian atmosphere using OMEGA/Mars Express and IR ground-based measurements

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T. Encrenaz, B. Bézard (1), R. Melchiorri, T. Fouchet, P. Drossart (1), T. Greathouse (2), M. Richter (3), B. Gondet, Y. Langevin, J.-P. Bibring (4), F. Forget (5), F. Lefèvre (6), S. Atreya (7) (1) LESIA, Observatoire de Paris, France; (2) LPI, Houston, USA; (3) UC Davis, USA; (4) IAS, Orsay, France; (5) LMD, Paris, France;(6) SA, Paris, France; (7) Un. Michigan, Ann Arbor, USA

presented by: Therese Encrenaz email-therese.encrenaz@obspm.fr, phone-33 1 45 07 76 91, fax-33 1 45 07 28 06

The TEXES instrument, mounted at the NASA/IRTF, has been used to map H2O2 and H2O on Mars (Encrenaz et al., Icarus 170, 424, 2004; Icarus 179, 43, 2005a). While the H2O map appears in good agreement with the GCM and previous measurements, there are some departures between the H2O2 maps and the GCM predictions. Heterogeneous chemistry may help resolving the discrepancies (Lefèvre et al., 2nd Mars workshop, Granada, 2006).

OMEGA/MEx has also been used to map H2O over the seasonal cycle (Encrenaz et al., A& A 441, L9, 2005b; Melchiorri et al., submitted to PSS, 2006). Results appear in general agreement with

the GCM and TES previous results. OMEGA has also been used to study the CO mixing ratio over Hellas as a function of solar longitude. An enhancement by 2 to 3 is observed during southern winter, in global agreement with the GCM predictions (Forget et al., 2nd Mars workshop, Granada, 2006).

Cassini views on Saturn's rings

Cécile Ferrari  UMR AIM, University Paris 7 and SAp/DAPNIA/DSM/CEA Saclay, France

presented by: Cécile Ferrari, tél: 33169087829, fax: 33169086577

The Cassini mission is opening a new era in the exploration of Saturn's rings, in the quest for answers on still pending issues on their origin and evolution: