SEIS: Insight’s Seismic Experiment for Internal Structure of Mars

By the end of 2018, 42 years after the landing of the two Viking seismometers on Mars, InSight will deploy onto Mars’ surface the SEIS (Seismic Experiment for Internal Structure) instrument; a six-axes seismometer equipped with both a long-period three-axes Very Broad Band (VBB) instrument and a three-axes short-period (SP) instrument. These six sensors will cover a broad range of the seismic bandwidth, from 0.01 Hz to 50 Hz, with possible extension to longer periods. Data will be transmitted in the form of three continuous VBB components at 2 sample per second (sps), an estimation of the short period energy content from the SP at 1 sps and a continuous compound VBB/SP vertical axis at 10 sps. The continuous streams will be augmented by requested event data with sample rates from 20 to 100 sps. SEIS will improve upon the existing resolution of Viking’s Mars seismic monitoring by a factor of ∼ 2500 at 1 Hz and ∼ 200 000 at 0.1 Hz. An additional major improvement is that, contrary to Viking, the seismometers will be deployed via a robotic arm directly onto Mars’ surface and will be protected against temperature and wind by highly efficient thermal and wind shielding. Based on existing knowledge of Mars, it is reasonable to infer a moment magnitude detection threshold of Mw ∼ 3 at 40◦ epicentral distance and a potential to detect several tens of quakes and about five impacts per year. In this paper, we first describe the science goals of the experiment and the rationale used to define its requirements. We then provide a detailed description of the hardware, from the sensors to the deployment system and associated performance, including transfer functions of the seismic sensors and temperature sensors. We conclude by describing the experiment ground segment, including data processing services, outreach and education networks and provide a description of the format to be used for future data distribution

Computer modelling of crack growth in rubber-toughened polymers

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN016667 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Molecular dynamics calculation of elastic constants in Gay-Berne nematic liquid crystals

<F4.417e+05> In this paper we present a molecular dynamics calculation of the Frank elastic constants of a nematic liquid crystal. We study two well-known variants of the Gay-Berne potential, and determine the elastic constants by measuring orientational fluctuations as a function of wavevector, using reasonably large system sizes in the range 1000--8000 molecules. For some of the simulations, a set of Lagrangian constraints was applied in order to keep the director fixed along one of the box axes, facilitating the measurement of fluctuations in components of the reciprocal-space order tensor <F5.754e+05><F5.273e+05><F5.754e+05><F5.273e+05> Q(k)<F4.417e+05> in the director frame. <F5.754e+05>1 Introduction<F4.417e+05> In a nematic liquid crystal, the distribution of molecular positions is translationally invariant but the orientational distribution shows preferential alignment along the director. Deviations from uniform alignment occur principally through the existence of defects (..

Replicated Data and Domain Decomposition Molecular Dynamics Techniques for the Simulation of Anisotropic Potentials

The implementation of parallel molecular dynamics techniques is discussed in the context of the simulation of single-site anisotropic potentials. We describe the use of both replicated data and domain decomposition approaches to molecular dynamics and present results for systems of upto 65536 Gay-Berne molecules on a range of parallel computers (Transtech i860/XP Paramid, Intel iPSC/860 Hypercube, Cray T3D). We find excellent parallel speed-ups are possible for both techniques, with the domain decomposition method found to be the most efficient for the largest systems studied. I. INTRODUCTION In recent years molecular dynamics (MD) has become one of the most widely used techniques for studying condensed systems. It can be applied to a wide range of problems including the simulation of liquids [1], biological systems [2], and the investigation of complex fluids such as liquid crystals [3], colloids [4] and micellar systems [5]. In most of these cases molecular dynamics involves the s..

The European Experience of Educational Seismology

International audienceThis chapter provides an overview of the last two decades’ European experiences in educational seismology and describes the different contexts in which they have been developed. The basic idea of these educational projects is that seismology may represent an efficient communication vehicle for teaching a wide range of basic earth science topics through laboratory practices and educational activities. Moreover, it is also an effective tool to raise in the young citizens the awareness on the earthquake risk and possible mitigation actions. In this frame, several seismic stations with different technologies were installed in schools across Europe. The scientific support of researchers and the need to establish strong links between teachers and researchers attribute to the school an active role in the knowledge process using the scientific laboratory practice by adopting the ‘learning by doing’ modern approach of science communication (R. Schank C. Cleary, 1995). Some educational activities correlated with seismological projects are presented, following different strategies depending on the country, but all aimed at building a new way to communicate science in the schools. The new vogue is the opening towards social media and blogs. This generalises the concept of an educational Geoscience website making it an e-platform for science communication and multimedia data sharing, where researchers, teachers, students and education operators can interact and constantly be kept informed of ongoing activities and relevant events

The European experience of educational seismology

This chapter provides an overview of last two decades, European experiences in educational seismology and describes the different contexts in which they have been developed. The basic idea of these educational projects is that Seismology may represent an efficient communication vehicle for teaching a wide range of basic Earth sci-ence topics through laboratory practices and educational activities. Moreover it is also an effective tool to raise in the young citizens the awareness on the earthquake risk and possible mitigation actions. In this frame several seismic stations with different technologies were installed in schools across Europe. The scientific support of re-searchers and the need to establish strong links between teachers and researchers attribute to the school an active role in the knowledge process using the scientific laboratory practice by adopting the “learning by doing” modern approach of science communication (R. Schank and C. Cleary, 1995, Engines for Education, Ed. Routledge, 248 pp). Some educational activities correlated with seismological projects are presented, following different strategies depending on the country, but all aimed at building a new way to communicate science in the schools. The new vogue is the opening toward social networks and blogs. This generalizes the concept of an educational Geoscience website making it an e-platform for science communication and multimedia data sharing, where researchers, teachers, students and education op-erators can interact and constantly be kept informed of ongoing activities and relevant events. All of these 'seismology at school' initiatives rely on the concept of school networking and will merge in the European project NERA (Network of European Research Infrastructures for Earthquake Risk Assessment and Mitigation, http://www.nera-eu.org/) where a spe-cific workpackage is dedicated to networking school seismology programs