Implications of the Global Surface Fault Distribution and of Lithospheric Cooling

This contribution presents a model that links the observed distribution of surface faults to the spatial distribution of marsquakes. The annual seismic moment budget is computed based on the as-sumption that global cooling and subsequent shrink-ing of Mars is the main source of strain today [1]. A truncated Gutenberg-Richter distribution is used to re-late the seismic moment budget to marsquake frequen-cies. We have derived a theoretical relation for the limitation of quake size by the lengths of the individual faults. This relation is used for the simulation of epi-center catalogs that may serve as input data for the development of seismological experiments

Phobos DTM and Coordinate Refinement for Phobos-Grunt Mission Support.

Images obtained by the High Resolution Stereo Camera (HRSC) during recent Phobos flybys were used to study the proposed new landing site area of the Russian Phobos-Grunt mission, scheduled for launch in 2011 [1]. From the stereo images (resolution of up to 4.4 m/pixel), a digital terrain model (DTM) with a lateral resolution of 100 m per pixel and a relative point accuracy of ±15 m, was determined. Images and DTM were registered to the established Phobos control point network [7]. A map of the landing site area was produced enabling mission planers and scientists to extract accurate body-fixed coordinates of features in the Phobos Grunt landing site area

RiPKI: The Tragic Story of RPKI Deployment in the Web Ecosystem

Previous arXiv version of this paper has been published under the title "When BGP Security Meets Content Deployment: Measuring and Analysing RPKI-Protection of Websites", Proc. of Fourteenth ACM Workshop on Hot Topics in Networks (HotNets), New York:ACM, 2015Previous arXiv version of this paper has been published under the title "When BGP Security Meets Content Deployment: Measuring and Analysing RPKI-Protection of Websites", Proc. of Fourteenth ACM Workshop on Hot Topics in Networks (HotNets), New York:ACM, 2015Web content delivery is one of the most important services on the Internet. Access to websites is typically secured via TLS. However, this security model does not account for prefix hijacking on the network layer, which may lead to traffic blackholing or transparent interception. Thus, to achieve comprehensive security and service availability, additional protective mechanisms are necessary such as the RPKI, a recently deployed Resource Public Key Infrastructure to prevent hijacking of traffic by networks. This paper argues two positions. First, that modern web hosting practices make route protection challenging due to the propensity to spread servers across many different networks, often with unpredictable client redirection strategies, and, second, that we need a better understanding why protection mechanisms are not deployed. To initiate this, we empirically explore the relationship between web hosting infrastructure and RPKI deployment. Perversely, we find that less popular websites are more likely to be secured than the prominent sites. Worryingly, we find many large-scale CDNs do not support RPKI, thus making their customers vulnerable. This leads us to explore business reasons why operators are hesitant to deploy RPKI, which may help to guide future research on improving Internet security

Surface softening in metal-ceramic sliding contacts: An experimental and numerical investigation

This study investigates the tribolayer properties at the interface of ceramic/metal (i.e., WC/W) sliding contacts using various experimental approaches and classical atomistic simulations. Experimentally, nanoindentation and micropillar compression tests, as well as adhesion mapping by means of atomic force microscopy, are used to evaluate the strength of tungsten?carbon tribolayers. To capture the influence of environmental conditions, a detailed chemical and structural analysis is performed on the worn surfaces by means of XPS mapping and depth profiling along with transmission electron microscopy of the debris particles. Experimentally, the results indicate a decrease in hardness and modulus of the worn surface compared to the unworn one. Atomistic simulations of nanoindentation on deformed and undeformed specimens are used to probe the strength of the WC tribolayer and despite the fact that the simulations do not include oxygen, the simulations correlate well with the experiments on deformed and undeformed surfaces, where the difference in behavior is attributed to the bonding and structural differences of amorphous and crystalline W-C. Adhesion mapping indicates a decrease in surface adhesion, which based on chemical analysis is attributed to surface passivation

High-Resolution Phobos Atlas derived from High Resolution Stereo Camera (HRSC) Images on Mars Express

We deal with the Martian satellite Phobos and present a global orthomosaic and an atlas. The mosaic and maps are based on image data obtained by the High Resolution Stereo Camera (HRSC) (Jaumann et al., 2007), the pushbroom scanner on Mars Express (MEX). The new atlas is an update of the previously released version (Wählisch et al., 2010), which was derived from images of the Super Resolution Channel (SRC) (Oberst et al., 2008), the CCD frame camera of the HRSC. Due to the different nature of the camera systems (9 line CCD scanner vs. the 1K CCD frame), the orthoimage production for the mosaic differs considerably. We selected 18 HRSC scenes, obtained during MEX Phobos flybys from 2004 to 2011. We have carried out a photogrammetric adjustment for the selected scenes (5 images each) (Willner et al., 2013), which yields improved orientation data for all 90 images. As the distance between the spacecraft and Phobos varied between approx. 100 and 2240 km, image resolutions range from 3.7 m/ pixel to 98.5 m/ pixel. 10 images were selected guaranteeing the Phobos coverage for production of a global mosaic. We used the newly updated Digital Terrain Model (DTM) (Willner et al., 2013) for ortho-rectification. The 10 images (resolutions from 3.7 m/ pixel to 24.0 m/ pixel) were resampled to a uniform resolution of 16 pixels/ degree or 12.11 m/ pixel, and subsequently superimposed. Phobos is in a synchronous rotation in a near-circular orbit around Mars. A gap on the trailing hemisphere, which could not been imaged by HRSC due to the illuminating conditions, was closed by three Viking orthoimages. The atlas consists of 6 topographic image maps, which were created at a scale of 1: 50,000 (Wählisch et al., 2013). The mosaics in the equator region are in Mercator projection. Submosaics using 3 images in each case were generated for the North and South poles in Stereographic projection. The atlas shows two different types of contour lines: sheet 1 (map 1 to 3) of the atlas displays dynamic height contours obtained from gravity field modelling (Shi et al., 2012), useful to identify down-slope direction and mobility of surface materials. On sheet 2 (map 1 to 3), contour lines represent geometrical heights above the sphere (Rmean = 11.1 km) derived from the global DTM. For simplicity, the same sphere was chosen as horizontal reference. Finally, 17 craters with approved names by the International Astronomical Union (IAU) are marked in the map, for which the coordinates and dimensions were re-determined