Odyssey: a solar system mission     

B. Christophe  P. H. Andersen  J. D. Anderson  S. Asmar  Ph. Bério  O. Bertolami  R. Bingham  F. Bondu  Ph. Bouyer  S. Bremer  J.-M. Courty  H. Dittus  B. Foulon  P. Gil  U. Johann  J. F. Jordan  B. Kent  C. Lämmerzahl  A. Lévy  G. Métris  O. Olsen  J. Pàramos  J. D. Prestage  S. V. Progrebenko  E. Rasel  A. Rathke  S. Reynaud  B. Rievers  E. Samain  T. J. Sumner  S. Theil  P. Touboul  S. Turyshev  P. Vrancken  P. Wolf  N. Yu 《Experimental Astronomy》2009,23(2):529-547

The Solar System Odyssey mission uses modern-day high-precision experimental techniques to test the laws of fundamental physics which determine dynamics in the solar system. It could lead to major discoveries by using demonstrated technologies and could be flown within the Cosmic Vision time frame. The mission proposes to perform a set of precision gravitation experiments from the vicinity of Earth to the outer Solar System. Its scientific objectives can be summarized as follows: (1) test of the gravity force law in the Solar System up to and beyond the orbit of Saturn; (2) precise investigation of navigation anomalies at the fly-bys; (3) measurement of Eddington’s parameter at occultations; (4) mapping of gravity field in the outer solar system and study of the Kuiper belt. To this aim, the Odyssey mission is built up on a main spacecraft, designed to fly up to 13 AU, with the following components: (a) a high-precision accelerometer, with bias-rejection system, measuring the deviation of the trajectory from the geodesics, that is also giving gravitational forces; (b) Ka-band transponders, as for Cassini, for a precise range and Doppler measurement up to 13 AU, with additional VLBI equipment; (c) optional laser equipment, which would allow one to improve the range and Doppler measurement, resulting in particular in an improved measurement (with respect to Cassini) of the Eddington’s parameter. In this baseline concept, the main spacecraft is designed to operate beyond the Saturn orbit, up to 13 AU. It experiences multiple planetary fly-bys at Earth, Mars or Venus, and Jupiter. The cruise and fly-by phases allow the mission to achieve its baseline scientific objectives [(1) to (3) in the above list]. In addition to this baseline concept, the Odyssey mission proposes the release of the Enigma radio-beacon at Saturn, allowing one to extend the deep space gravity test up to at least 50 AU, while achieving the scientific objective of a mapping of gravity field in the outer Solar System [(4) in the above list].   相似文献   

Future changes in vegetation and ecosystem function of the Barents Region   总被引：1，自引：0，他引：1  

Annett Wolf  Terry V. Callaghan  Karin Larson 《Climatic change》2008,87(1-2):51-73

The dynamic vegetation model (LPJ-GUESS) is used to project transient impacts of changes in climate on vegetation of the Barents Region. We incorporate additional plant functional types, i.e. shrubs and defined different types of open ground vegetation, to improve the representation of arctic vegetation in the global model. We use future climate projections as well as control climate data for 1981–2000 from a regional climate model (REMO) that assumes a development of atmospheric CO₂-concentration according to the B2-SRES scenario [IPCC, Climate Change 2001: The scientific basis. Contribution working group I to the Third assessment report of the IPCC. Cambridge University Press, Cambridge (2001)]. The model showed a generally good fit with observed data, both qualitatively when model outputs were compared to vegetation maps and quantitatively when compared with observations of biomass, NPP and LAI. The main discrepancy between the model output and observed vegetation is the overestimation of forest abundance for the northern parts of the Kola Peninsula that cannot be explained by climatic factors alone. Over the next hundred years, the model predicted an increase in boreal needle leaved evergreen forest, as extensions northwards and upwards in mountain areas, and as an increase in biomass, NPP and LAI. The model also projected that shade-intolerant broadleaved summergreen trees will be found further north and higher up in the mountain areas. Surprisingly, shrublands will decrease in extent as they are replaced by forest at their southern margins and restricted to areas high up in the mountains and to areas in northern Russia. Open ground vegetation will largely disappear in the Scandinavian mountains. Also counter-intuitively, tundra will increase in abundance due to the occupation of previously unvegetated areas in the northern part of the Barents Region. Spring greening will occur earlier and LAI will increase. Consequently, albedo will decrease both in summer and winter time, particularly in the Scandinavian mountains (by up to 18%). Although this positive feedback to climate could be offset to some extent by increased CO₂ drawdown from vegetation, increasing soil respiration results in NEE close to zero, so we cannot conclude to what extent or whether the Barents Region will become a source or a sink of CO₂.  相似文献   

Potential impact of climate change and reindeer density on tundra indicator species in the Barents Sea region     

Christoph Zöckler  Lera Miles  Lucy Fish  Annett Wolf  Gareth Rees  Fiona Danks 《Climatic change》2008,87(1-2):119-130

Climate change is expected to alter the distribution of habitats and thus the distribution of species connected with these habitats in the terrestrial Barents Sea region. It was hypothesised that wild species connected with the tundra and open-land biome may be particularly at risk as forest area expands. Fourteen species of birds were identified as useful indicators for the biodiversity dependent upon this biome. By bringing together species distribution information with the LPJ-GUESS vegetation model, and with estimates of future wild and domestic reindeer density, potential impacts on these species between the present time and 2080 were assessed. Over this period there was a net loss of open land within the current breeding range of most bird species. Grazing reindeer were modelled as increasing the amount of open land retained for nine of the tundra bird species.  相似文献   

LINET—An international lightning detection network in Europe   总被引：1，自引：0，他引：1  

Hans D. Betz  Kersten Schmidt  Pierre Laroche  Patrice Blanchet  Wolf P. Oettinger  Eric Defer  Z. Dziewit  J. Konarski 《Atmospheric Research》2009,91(2-4):564-573

During the past years a VLF/LF lightning detection network (LINET) was developed at the University of Munich, which provides continuous data for both research and operational purposes. In particular, the network introduces five new features: a) total lightning capability: both cloud-to-ground strokes (CG) and cloud lightning (IC) are measured; b) low-amplitude reporting: weak lightning events from discharge channel with currents well below 5 kA are detected within the central part of the network, whereby IC events dominate; c) new 3D-discrimination: a time-of-arrival method is utilized to separate CG from IC with good reliability, provided that the sensor baseline does not exceed ~ 250 km; d) IC emission height: for each cloud event a height is determined which is thought to reflect the central region of the involved channel; and e) optimised location accuracy: due to precision and combined action of all influential network components, complemented by site-error corrections, the position accuracy of strokes reaches an average value as small as ~ 150 m, whereby false locations (‘outliers’) rarely occur. During international co-operations LINET has been deployed in four continents: Europe (initially Germany), South America (area of Bauru, Brazil), Australia (around Darwin), and Central Africa (Benin). Since the features quoted above could be verified in the tests, a 65-sensor network was established in Europe and started on May 1, 2006, in co-operation with the service company nowcast. LINET covers a wide area approximately from longitude − 10° to 25° to latitude 35° to 66°; it is available for scientific projects and officially utilized by the German Weather Service for operational purposes. Meanwhile, the network was extended by deployment of additional sites so that it comprises about 90 sensors in 17 countries.  相似文献   

Helium-rich hot subdwarfs and single low-mass white dwarfs: formation mechanisms and further implications     

Stephen Justham  Philipp Podsiadlowski  Zhanwen Han  Christian Wolf 《Astrophysics and Space Science》2010,329(1-2):3-10

Variations in the mass loss from single stars have been used to explain the existence of hot subdwarf stars and the existence of single low-mass white dwarfs (LMWDs). Hence remaining uncertainty in mass loss from single red-giant stars is important to the understanding of these problems. However, natural formation channels for hot subdwarfs and single LMWDs have also been proposed which do not rely on unexplained mass loss from single red-giant stars. We outline these, and discuss how the different mechanisms could be distinguished. For example, a formation channel for single LMWDs which involves the break-up of a binary system by a type Ia supernova should produce a population of single LMWDs with a distinct kinematic signature. If that population is found to exist, it could be used to study one of the popular single-degenerate formation channels for type Ia supernovae in a previously impossible way. In addition, we examine the formation of helium-rich sdO stars—which are shown to emerge from one of the previously existing binary formation channels for hot subdwarfs. Both the SN Ia formation mechanism for single LMWDs and the formation channel for He-sdOs are a natural consequence of existing models. Hence if these formation channels do not work at all, then the result is a significant one.  相似文献   

The First Arab Impact Cratering and Astrogeology Conference,Amman, Jordan, 9–11 November 2009—An appreciation     

Wolf Uwe Reimold 《Meteoritics & planetary science》2010,45(2):157-160

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Deglacial land emergence and lateral upper-mantle heterogeneity in the Svalbard Archipelago—II. Extended results for high-resolution load models     

Georg Kaufmann  Detlef Wolf 《Geophysical Journal International》1996,127(1):125-140

In Paper I (Breuer & Wolf 1995), a preliminary interpretation of the postglacial land emergence observed at a restricted set of six locations in the Svalbard Archipelago was given. The study was based on a simple model of the Barents Sea ice sheet and suggested increases in lithosphere thickness and asthenosphere viscosity with increasing distance from the continental margin.
In the present paper, the newly developed high-resolution load model. BARENTS-2, and land-uplift observations from an extended set of 25 locations are used to study further the possibility of resolving lateral heterogeneity in the upper mantle below the northern Barents Sea. A comparison of the calculated and observed uplift values shows that the lithosphere thickness is not well resolved by the observations, although values above 110 km are most common for this parameter. In contrast to this, there are indications of a lateral variation of asthenosphere viscosity. Whereas values in the range 10¹⁸-10²⁰Pas are inferred for locations close to the continental margin, 10²⁰-10²¹ Pa s are suggested further away from the margin.
A study of the sensitivity of the values found for lithosphere thickness and asthenosphere viscosity to modifications of load model BARENTS-2 shows that such modifications can be largely accommodated by appropriate changes in lithosphere thickness, whereas the suggested lateral variation of asthenosphere viscosity is essentially unaffected. An estimate of the influence of the Fennoscandian. ice sheet leads to the conclusion that its neglect results in an underestimation of the thickness of the Barents Sea ice sheet by about 10 per cent.  相似文献   

Note on estimates of the glacial-isostatic decay spectrum for Fennoscandia     

Detlef Wolf 《Geophysical Journal International》1996,127(3):801-805

For more than 30 years, Sauramo's (1958) shoreline diagram of the Fennoscandian uplift has been used in geophysical studies for estimates of the glacial-isostatic decay spectrum in order to infer from it the viscosity stratification in the Earth's mantle below Fennoscandia. The intent of the present note is to point out that more recent geological studies suggest that Sauramo's shoreline diagram is an incorrect representation of the Fennoscandian uplift. Geophysical interpretations based on the diagram may therefore require revision.  相似文献   

Editorial     

Wolf Tietze 《Geoforum》1973,4(1):3

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Südosteuropa-literatur     

Wolf Tietze 《Geoforum》1971,2(2):96

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