Galileo in-situ dust measurements in Jupiter’s gossamer rings

Galileo was the first artificial satellite to orbit Jupiter. During its late orbital mission the spacecraft made two passages through the giant planet’s gossamer ring system. The impact-ionization dust detector on board successfully recorded dust impacts during both ring passages and provided the first in-situ measurements from a dusty planetary ring. During the first passage—on 5 November 2002 while Galileo was approaching Jupiter—dust measurements were collected until a spacecraft anomaly at 2.33R_J (Jupiter radii) just 16 min after a close flyby of Amalthea put the spacecraft into a safing mode. The second ring passage on 21 September 2003 provided ring dust measurements down to about 2.5R_J and the Galileo spacecraft was destroyed shortly thereafter in a planned impact with Jupiter. In all, a few thousand dust impacts were counted with the instrument accumulators during both ring passages, but only a total of 110 complete data sets of dust impacts were transmitted to Earth. Detected particle sizes range from about 0.2 to 5 μm, extending the known size distribution by an order of magnitude towards smaller particles than previously derived from optical imaging [Showalter, M.R., de Pater, I., Verbanac, G., Hamilton, D.P., Burns, J.A., 2008. Icarus 195, 361-377; de Pater, I., Showalter, M.R., Macintosh, B., 2008. Icarus 195, 348-360]. The grain size distribution increases towards smaller particles and shows an excess of these tiny motes in the Amalthea gossamer ring compared to the Thebe ring. The size distribution for the Amalthea ring derived from our in-situ measurements for the small grains agrees very well with the one obtained from images for large grains. Our analysis shows that particles contributing most to the optical cross-section are about 5 μm in radius, in agreement with imaging results. The measurements indicate a large drop in particle flux immediately interior to Thebe’s orbit and some detected particles seem to be on highly-tilted orbits with inclinations up to 20°. Finally, the faint Thebe ring extension was detected out to at least 5R_J, indicating that grains attain higher eccentricities than previously thought. The drop interior to Thebe, the excess of submicron grains at Amalthea, and the faint ring extension indicate that grain dynamics is strongly influenced by electromagnetic forces. These findings can all be explained by a shadow resonance as detailed by Hamilton and Krüger [Hamilton, D.P., Krüger, H., 2008. Nature 453, 72-75].     

STAGES: the Space Telescope A901/2 Galaxy Evolution Survey

We present an overview of the Space Telescope A901/2 Galaxy Evolution Survey (STAGES). STAGES is a multiwavelength project designed to probe physical drivers of galaxy evolution across a wide range of environments and luminosity. A complex multicluster system at   z ∼ 0.165  has been the subject of an 80-orbit F606W Hubble Space Telescope (HST) /Advanced Camera for Surveys (ACS) mosaic covering the full     span of the supercluster. Extensive multiwavelength observations with XMM–Newton , GALEX, Spitzer , 2dF, Giant Metrewave Radio Telescope and the 17-band COMBO-17 photometric redshift survey complement the HST imaging. Our survey goals include simultaneously linking galaxy morphology with other observables such as age, star formation rate, nuclear activity and stellar mass. In addition, with the multiwavelength data set and new high-resolution mass maps from gravitational lensing, we are able to disentangle the large-scale structure of the system. By examining all aspects of an environment we will be able to evaluate the relative importance of the dark matter haloes, the local galaxy density and the hot X-ray gas in driving galaxy transformation. This paper describes the HST imaging, data reduction and creation of a master catalogue. We perform the Sérsic fitting on the HST images and conduct associated simulations to quantify completeness. In addition, we present the COMBO-17 photometric redshift catalogue and estimates of stellar masses and star formation rates for this field. We define galaxy and cluster sample selection criteria, which will be the basis for forthcoming science analyses, and present a compilation of notable objects in the field. Finally, we describe the further multiwavelength observations and announce public access to the data and catalogues.     

Space monitoring of pollution of the Russian sector of the Azov-Black Sea basin in 2008

Technology of space monitoring of the state of water bodies and results of its application for studying the Azov-Black Sea basin in 2008 are considered. Based on the processing of more than 1000 satellite images and ground-based station data, basic characteristic features of the marine environmental pollution are determined which are connected with suspension dispersion, phytoplankton and algae growth, ship dumping of oil products (more than 62 oil patches were revealed), etc. The influence of dynamic structures in the coastal zone on the spatiotemporal distribution of the sea surface pollution parameters, and their contribution to mechanisms of water purification and self-purification are estimated. In particular, new data are obtained about the evolution of “Caucasian anticyclones,” about the dates of intensification of the Main Black Sea Current, and about features of coccolithophore bloom in the abyssal area of the Black Sea, etc.     

Internal structural geometry of the Paleozoic of Graz

The Paleozoic of Graz is an isolated nappe complex of about 1,500 km² size and belongs to the Austroalpine units of the eastern European Alps. Despite more than 500 publications on stratigraphy, paleontology and local structure, many aspects of the internal geometry of this complex as a whole remained unclear. In this contribution, we present integrated geological profiles through the entire nappe complex. Based on these profiles, we present (1) a simplified lithological subdivision into 13 rock associations, (2) a modified tectonostratigraphy where we consider only two major tectonic units: an upper and a lower nappe system and in which we abandon the traditionally used facies nappe concept, and (3) a modified paleogeography for the whole complex. Finally, we discuss whether the internal deformation of the Paleozoic of Graz is of Variscan or Eo-Alpine age and which of the published models best explain the tectonic evolution of the Paleozoic of Graz.     

Analytical Solutions for Flow Fields near Drain-and-Gate Reactive Barriers

Permeable reactive barriers (PRBs) are a popular technology for passive contaminant remediation in aquifers through installation of reactive materials in the pathway of a plume. Of fundamental importance are the degree of remediation inside the reactor (residence time) and the portion of groundwater intercepted by a PRB (capture width). Based on a two-dimensional conformal mapping approach (previously used in related work), the latter is studied in the present work for drain-and-gate (DG) PRBs, which may possess a collector and a distributor drain (“full” configuration) or a collector drain only (“simple” configuration). Inherent assumptions are a homogeneous unbounded aquifer with a uniform far field, in which highly permeable drains establish constant head boundaries. Solutions for aquifer flow fields in terms of the complex potential are derived, illustrated, and analyzed for doubly symmetric DG configurations and arbitrary reactor hydraulic resistance as well as ambient groundwater flow direction. A series of practitioner-friendly charts for capture width is given to assist in PRB design and optimization without requiring complex mathematics. DG PRBs are identified as more susceptible to flow divergence around the reactor than configurations using impermeable side structures (e.g., funnel-and-gate), and deployment of impermeable walls on drains is seen to mitigate this problem under certain circumstances.     

How Much Physiology is Needed in Forest Gap Models for Simulating Long-Term Vegetation Response to Global Change? Challenges, Limitations, and Potentials

Gap models were introduced over 30 years ago to examine the dynamics of forestvegetation structure and species composition based on plant populationdynamics. While there have been many advances, gap models remain heavilycriticized for their lack of attention to physiology, particularly as itaffects their ability to simulate forest response to elevated CO₂concentration and climatic change. In this paper we provide a summary andsynthesis of the results from the Gap Model Comparison Workshop that was heldin July, 1999 at Pingree Park, Colorado (U.S.A.). We identify some grandchallenges for the future development of forest gap models and discusslimitations as well as potentials of this modeling approach.     

Die rezente hydrothermal-sedimentäre Lagerstätte Atlantis-II-Tief im Roten Meer

Zusammenfassung Die in Entstehung befindliche hydrothermal-sedimentäre Lagerstätte Atlantis-II-Tief im Roten Meer wurde in den Jahren 1969, 1971 und 1972 von den Forschungsschiffen Wando River und Valdivia aus genauer untersucht. Die Detailkartierung zeigt eine Fallenstruktur, die hauptsächlich durch NW-streichende Grabenrandverwerfungen hervorgerufen wurde. Die in die se Depression in ihren tiefsten Teil einströmenden metallhaltigen Solen hielten das für die Lagerstättenbildung, besonders das für die Sulfidausfällung nötige Milieu über längere Zeit aufrecht. Diese seit dem ausgehenden Pleistozän anhaltende stabile Situation wurde einige Male von Lava-Ausflüssen, tektonischen Ereignissen und Verlagerung der Quellen unterbrochen. Diese Vorgänge und die komplizierte Morphologie der solegefüllten Becken führten zu einer sehr komplexen Faziesentwicklung und stratigraphischen Abfolge. Insgesamt läßt sich, von den Quellen ausgehend, eine Zonierung von sulfidisch-silikatischer zu manganitischlimonitischer Ausfällung beobachten.

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The Atlantis II Deep, a hydrothermal-sedimentary metal depositin statu nascendi has been investigated in detail 1969, 1971 and 1972 with the research vessels Wando River and Valdivia. The new bathymetric map reveals a trap structure mainly caused by NW-striking faults, limiting local grabens. The metalliferous brines discharging into the deepest part of this depression maintained the conditions necessary for the formation of the deposit, esp. of the sulfides, for a long time.This stabil situation active since the end of the Pleistocene was several times disturbed by lava flows, tectonic events and displacement of the discharge vents.These events and the complicate morphologic structure of the brine-filled deep are responsible for a very complex development of lithologic facies and the stratigraphic sequence. There is a general deposit differentiation from sulfidic-silicatic precipitation near the discharge points and formation of limonite and manganite outside the brines.

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Résumé Pendant les années 1969, 1971 et 1972 les gisements hydrothermaux sédimentaires Atlantis II, en voie de formation dans la Mer Rouge, ont fait l'objet de campagnes scientifiques détaillées entreprises par les navires océanographiques Wando River et Valdivia.La carte morphologique montre une structure de descente qui a été formée principalement par des failles de direction NW délimitant des graben. Les saumures métallifères affluant dans la partie la plus profonde de cette dépression ont maintenu pendant une certaine durée le milieu nécessaire à la formation du gisement, et surtout à la précipitation des sulfures. Cette situation restée stable depuis la fin du Pléistocène a été interrompue plusieurs fois des émissions basaltiques, par des dislocations tectoniques et par le déplacement des sources. Ces événements, ainsi que la morphologie compliquée du bassin rempli de saumures, ont conduit à un développement très complexe des faciès lithologiques et de la séquence stratigraphique. Dans l'ensemble on peut constater une zonation des faciès avec précipitations sulfurosilicatées près des points d'entrée des saumures et manganolimonitiques plus à l'écart.

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