Methane evolution from UV-irradiated spacecraft materials under simulated martian conditions: Implications for the Mars Science Laboratory (MSL) mission

Fifteen organic and three inorganic compounds were tested for methane (CH₄) evolution under simulated martian conditions of 6.9 mbar; UVC (200-280 nm) flux of 4 W m⁻²; 20 °C; simulated optical depth of 0.1; and a Mars gas composition of CO₂ (95.3%), N₂ (2.7%), Ar (1.7%), O₂ (0.13%), and water vapor (0.03%). All three inorganic compounds (i.e., NaCl, CaCO₃, graphite) failed to evolve methane at the minimum detection level 0.5 ppm, or above. In contrast, all organic compounds evolved methane when exposed to UV irradiation under simulated martian conditions. The polycyclic aromatic hydrocarbon, pyrene, released the most methane per unit of time at 0.175 nmol CH₄ g⁻¹ h⁻¹, and a spectral reflectance target material used for the MER rovers and Phoenix lander released the least methane at 0.00065 nmol CH₄ cm⁻² h⁻¹. Methane was also released from UV-killed bacterial endospores of Bacillus subtilis. Although all organic compounds evolved methane when irradiated with UV photons under martian conditions, the concentrations of residual organics, biogenic signature molecules, and dead microbial cells should be relatively low on the exterior surfaces of the MSL rover, and, thus, not significant sources of methane contamination. In contrast, kapton tape was found to evolve methane at the rate of 0.00165 nmol CH₄ cm⁻² h⁻¹ (16.5 nmol m⁻² h⁻¹) under the UV and martian conditions tested. Although the evolution of methane from kapton tape was found to decline over time, the large amount of kapton tape used on the MSL rover (lower bound estimated at 3 m²) is likely to create a significant source of terrestrial methane contamination during the early part of the mission.     

Integrating radar stratigraphy with high resolution visible stratigraphy of the north polar layered deposits,Mars

Shallow Radar (SHARAD) on board NASA’s Mars Reconnaissance Orbiter has successfully detected tens of reflectors in the subsurface of the north polar layered deposits (NPLD) of Mars. Radar reflections are hypothesized to originate from the same material interfaces that result in visible layering. As a first step towards verifying this assumption, this study uses signal analyses and geometric comparisons to quantitatively examine the relationship between reflectors and visible layers exposed in an NPLD outcrop. To understand subsurface structures and reflector geometry, reflector surfaces have been gridded in three dimensions, taking into account the influence of surface slopes to obtain accurate subsurface geometries. These geometries reveal reflector dips that are consistent with optical layer slopes. Distance–elevation profiling of subsurface reflectors and visible layer boundaries reveals that reflectors and layers demonstrate similar topography, verifying that reflectors represent paleosurfaces of the deposit. Statistical and frequency-domain analyses of the separation distances between successive layers and successive reflectors confirms the agreement of radar reflector spacing with characteristic spacing of certain visible layers. Direct elevation comparisons between individual reflectors and discrete optical layers, while necessary for a one-to-one correlation, are complicated by variations in subsurface structure that exist between the outcrop and the SHARAD observations, as inferred from subsurface mapping. Although these complications have prevented a unique correlation, a genetic link between radar reflectors and visible layers has been confirmed, validating the assumption that radar reflectors can be used as geometric proxies for visible stratigraphy. Furthermore, the techniques for conducting a stratigraphic integration have been generalized and improved so that the integration can be undertaken at additional locations.     

Geochemical studies of the SUBO 18 (Enkingen) drill core and other impact breccias from the Ries crater,Germany

Suevite and melt breccia compositions in the boreholes Enkingen and Polsingen are compared with compositions of suevites from other Ries boreholes and surface locations and discussed in terms of implications for impact breccia genesis. No significant differences in average chemical compositions for the various drill cores or surface samples are noted. Compositions of suevite and melt breccia from southern and northeastern sectors of the Ries crater do not significantly differ. This is in stark contrast to the published variations between within‐crater and out‐of‐crater suevites from northern and southern sectors of the Bosumtwi impact structure, Ghana. Locally occurring alteration overprint on drill cores—especially strong on the carbonate‐impregnated suevite specimens of the Enkingen borehole—does affect the average compositions. Overall, the composition of the analyzed impact breccias from Ries are characterized by very little macroscopically or microscopically recognized sediment‐clast component; the clast populations of suevite and impact melt breccia are dominated consistently by granitic and intermediate granitoid components. The Polsingen breccia is significantly enriched in a dioritic clast component. Overall, chemical compositions are of intermediate composition as well, with dioritic‐granodioritic silica contents, and relatively small contributions from mafic target components. Selected suevite samples from the Enkingen core have elevated Ni, Co, Cr, and Ir contents compared with previously analyzed suevites from the Ries crater, which suggest a small meteoritic component. Platinum‐group element (PGE) concentrations for some of the enriched samples indicate somewhat elevated concentrations and near‐chondritic ratios of the most immobile PGE, consistent with an extraterrestrial contribution of 0.1–0.2% chondrite‐equivalent.     

摄影测量与遥感之发展趋势和展望

0引言摄影测量与遥感的原理可定义为:确定物体表面反射或发射某特定波长的电磁辐射特性(如:能量、相位、极化、传播时间等),并由这些测量值中提取物体及其表面的几何特征(如位     

The complex X-ray spectrum of the isolated neutron star RBS1223

We present a first analysis of a deep X-ray spectrum of the isolated neutron star RBS1223 obtained with XMM-Newton. Spectral data from four new monitoring observations in 2005/2006 were combined with archival observations obtained in 2003 and 2004 to form a spin-phase averaged spectrum containing 290 000 EPIC-pn photons. This spectrum shows higher complexity than its predecessors, and can be parameterised with two Gaussian absorption lines superimposed on a blackbody. The line centers, E ₂≃2E ₁, could be regarded as supporting the cyclotron interpretation of the absorption features in a field B∼4×10¹³ G. The flux ratio of those lines does not support this interpretation. Hence, either feature might be of truly atomic origin.      

WASP-1b and WASP-2b: two new transiting exoplanets detected with SuperWASP and SOPHIE

We have detected low-amplitude radial-velocity variations in two stars, USNO-B1.0 1219–0005465 (GSC  02265–00107 = WASP–1  ) and USNO-B1.0 0964–0543604 (GSC  00522–01199 = WASP–2  ). Both stars were identified as being likely host stars of transiting exoplanets in the 2004 SuperWASP wide-field transit survey. Using the newly commissioned radial-velocity spectrograph SOPHIE at the Observatoire de Haute-Provence, we found that both objects exhibit reflex orbital radial-velocity variations with amplitudes characteristic of planetary-mass companions and in-phase with the photometric orbits. Line-bisector studies rule out faint blended binaries as the cause of either the radial-velocity variations or the transits. We perform preliminary spectral analyses of the host stars, which together with their radial-velocity variations and fits to the transit light curves yield estimates of the planetary masses and radii. WASP-1b and WASP-2b have orbital periods of 2.52 and 2.15 d, respectively. Given mass estimates for their F7V and K1V primaries, we derive planet masses 0.80–0.98 and 0.81–0.95 times that of Jupiter, respectively. WASP-1b appears to have an inflated radius of at least 1.33 R _Jup, whereas WASP-2b has a radius in the range 0.65–1.26 R _Jup.     

Modelling observed and future runoff from a glacierized tropical catchment (Cordillera Blanca, Perú)

Monthly runoff from the 34.3% glacierized tropical catchment of Llanganuco in the tropical Cordillera Blanca, Perú, is successfully simulated and compared with a measured 44 year time series. In the investigation area, the climate is characterized by all-year round homogenous temperature conditions and a strong variability in air humidity and moisture content of the atmosphere. Thus, contrary to the mid latitudes, the seasonal variation in glacier melt strongly depends on moisture-related variables, rather than on air temperature. The here presented ITGG-2.0-R model aims for these requirements. The lack of moisture-related input data other than precipitation demands for an intermediate calibration step. Net shortwave radiation, the emissivity of the atmosphere and a sublimation/melt ratio are related to precipitation amounts. Runoff is well simulated and correlates with the measured record with r² = 0.76. Seasonally obtained r² are only slightly smaller. On a long-term, the cumulative deviation is minor, and the mean annual cycle of runoff is reproduced rather well (r² = 0.99). Based on four different IPCC climate change scenarios, future runoff is simulated. All runoff scenarios are modelled for the respective steady-state glacier extent. This leads to a reduction in the glacier size and a decreased amount of glacier melt. On the other hand, direct runoff increases due to larger glacier free areas. Consequently, mean annual runoff remains almost unchanged, but the seasonality intensifies considerably with more runoff during the wet and less runoff during the dry season.     

Galaxies in Interaction

Posters: Because of the large number of contributions, some oral presentations had to be transferred into Posters. The reader is referred to the final programme for the actual allocation of Posters. A01 Chemical Enrichment of the Intracluster Medium A02 Structural analysis of high‐velocity clouds – Evidence for an interaction between the Milky Way and the Magellanic System A03 Multi‐Phase Chemo‐Dynamical SPH code for galaxy evolution A04 The proper motion of M33 A05 Wavelet analysis of Intra–group Light in Hickson Compact Groups A06 Evidence for an evolutionary connection between early and late type dwarf galaxies A07 Dwarf Galaxies in the NGC 5846 Group A08 X‐ray spectroscopy of serendipitous clusters of galaxies in XMM‐Newton observations A09 Evolution of smale scale systems of galaxies: X‐ray detected E+S galaxy pairs A10 Modelling Star Formation in Interacting Galaxies A11 NGC 1427A – the beginning of the end: a lonely dwarf irregular entering the dense core of the Fornax cluster A12 Dwarf galaxies in galaxy groups: Photo‐evaporation, orbits and gas stripping A13 High resolution stellar kinematics for the central component of the Polar Ring Galaxy NGC 4650A A14 The Influence of Environment on the Morphological Evolution of Disk‐Dominated Galaxies A15 Interactions and star formation in galaxies A16 Dust Condensations and Molecular Clouds in Interacting Spirals A17 Star formation rates and kinematics of modelled interacting galaxies A18 Evolution of Galaxies and the Tully–Fisher Relation A19 Evolution and Collision of Galaxies on the GRID A20 Multiwavelength observations of two S+E merger candidates: the Medusa and NGC 4441 A21 Interacting Galaxies in Small Galaxy Groups A22 Virial and total masses of galaxy triplets in the Local Supercluster A23 Simulations of Interaction Processes of Galaxies with the Intra‐Cluster Medium A24 Chemical evolution of the thick and thin disks of our Galaxy A25 Dust properties of UV‐bright galaxies at z ∼ 2 A26 Simulation of the Gravitational Collapse and Fragmentation of Rotating Molecular Clouds A27 NGC 5719/13: interacting spirals forming a counter‐rotating stellar disc A28 Starbursts in very metal‐poor dwarfs due to interactions and mergers: link to the processes in the high‐redshift young galaxies A29 Testing galaxy evolution in the field: morphology and properties of the diffuse X‐ray emission in shell galaxies A30 Effects of galactic winds on dIrrs with particular emphasis on NGC 1569 and the refill of superbubble cavities A31 Galaxy formation through merging at z ≈ 2 A32 3D simulations of the ISM‐ICM interaction of disk galaxies in clusters A33 Gas replenishment in ram pressure stripped disk galaxies A34 New Results on the Kinematics of the Outer Cluster System of NGC 1399 A35 Chemical gradient evolution in massive galaxy disk due to its minor merger with dwarf galaxy A36 The complex kinematics of galaxies in Hickson 62 A37 Dust in the outer regions of interacting galaxies A38 Dynamical interaction of M31 and M32 A39 A comparative study of galaxy properties in low‐ and high density environment A40 Compact Groups in Dense Environment: The Case of IC1370 A41 The Star Formation History of CG J1720‐67.8 A42 Galaxy populations in the infall regions of intermediate redshift clusters A43 The study of gravitational fragmentation in two‐clumps collisions A44 Star Formation Activity in Galaxy Clusters Near and Far A45 An Exploration of the Merging History of the Local Starburst Galaxy, NGC 3310 A46 The high‐velocity clouds of M31: tracers of galactic evolution A47 The Properties of Fossil Groups