The science process for selecting the landing site for the 2011 Mars Science Laboratory

The process of identifying the landing site for NASA’s 2011 Mars Science Laboratory (MSL) began in 2005 by defining science objectives, related to evaluating the potential habitability of a location on Mars, and engineering parameters, such as elevation, latitude, winds, and rock abundance, to determine acceptable surface and atmospheric characteristics. Nearly 60 candidate sites were considered at a series of open workshops in the years leading up to the launch. During that period, iteration between evolving engineering constraints and the relative science potential of candidate sites led to consensus on four final sites. The final site will be selected in the Spring of 2011 by NASA’s Associate Administrator for the Science Mission Directorate. This paper serves as a record of landing site selection activities related primarily to science, an inventory of the number and variety of sites proposed, and a summary of the science potential of the highest ranking sites.     

Assessing adequacy of spectrum‐matched ground motions for response history analysis

Response spectrum matching is commonly used to generate ground motions with response spectra matching a scenario target spectrum. There is some debate in the literature about whether spectrum‐matched motions lead to biased structural analysis results. Furthermore, there are no objective, quantitative criteria available for deciding whether a ground motion has been manipulated excessively by spectrum matching, and whether large modification may also lead to bias. This study investigates both of these issues by presenting the results of structural analysis using two reinforced concrete moment frame models and two earthquake scenarios, with suites of unmatched and matched ground motions. Through comparison with a robust benchmark, it is shown that no significant bias is introduced by spectrum matching. The period range and target damping values for matching are also investigated, and matching up to three times the fundamental period is shown to be beneficial in reducing dispersion in the results. Finally, these analyses were also used to investigate whether large changes in the ground motion lead to biased analysis results. Several potential measures of change are investigated, including those based on peak absolute ground motion, cumulative squared ground motion (absolute or normalized), and input energy into single‐degree‐of‐freedom systems. Although no systematic, statistically significant correlation is found for the analysis results in terms of any of these measures of change, tentative criteria are proposed, which may be used by analysts to aid in the decision of whether to accept or reject a spectrum‐matched motion. Copyright © 2012 John Wiley & Sons, Ltd.     

Fate of Pesticides and Their Transformation Products: First Flush Effects in a Semi‐Arid Catchment

Although it is known for many years, that transformation products (TPs) of pesticides are often more persistent, mobile, and sometimes more toxic than the parent compound, former catchment scale studies of substance release and flushing effects focused only on the parent compound. In this study, four river points were sampled in the Hula Valley, Israel, and samples were analyzed in the lab for chlorpyrifos (CP) and endosulfan residues (including transformation products; TPs). Sampling results of the first rainfall in autumn 2009 identified a strong release of most substances to the rivers. First flush effects of these substances were assessed regarding the risk for drinking water supply and ecology, like fresh water invertebrates and fish. Although, these substances were found in Jordan River water during the first significant rainfall the observed levels are below international drinking water guideline values with no adverse effects on human health in the region. However, the observed CP and chlorpyrifos oxon (CPO) levels are above the acute toxicity for fresh water invertebrates and fish. The study shows that the Hula Valley was an important source of pesticides and TPs at the Upper Jordan River basin and that substance flushing is extremely important for pesticides‐monitoring campaigns.     

Impact of acid sulfate soils on the geochemistry of rivers in south-western Finland

Large areas of acid sulfate (AS) soils are located along the coastal plains of Finland, and previous studies have shown that after reclamation they release extreme quantities of metals to watercourses in mid-western and northern Finland. In this study on streams of south-western Finland, where little information about AS soils is available, these soils were found to exhibit the same pattern of elevated metal- and sulfate concentrations as in the notorious AS soil landscapes of mid-western Finland. Meteorologically/hydrologically driven temporal variations of these elements were great in the most affected streams. There were also significant positive implications regarding future environmental work; AS soils in the highlighted region were found to cause sudden temporal influxes of acidic water only in the most affected streams, indicating that the overburden and soils of the area discharge well buffered water. Moreover, it was indicated that the high (less toxic) metal concentrations are largely caused by erosion of suspended phyllosilicates (<0.45 μm) from farmland rather than by AS soils.     

Chronology of the Lower and Middle Palaeolithic in NW Europe: developer-funded investigations at Dunbridge,Hampshire, southern England

This paper reports important findings relating to the chronology of Palaeolithic occupation, artefact typology and Quaternary fluvial deposits from a geoarchaeological watching brief undertaken over 17 years at Kimbridge Farm Quarry, Dunbridge, Hampshire. Sections were recorded and sampled and 198 artefacts, principally hand axes, were collected, with the primary aim of enhancing understanding of the geological context of the richest Lower Palaeolithic assemblage from Hampshire. Digital terrain modelling was used to characterize the three-dimensional form of the fluvial geology. Two gravel terraces have been confirmed: an upper Belbin Formation, which contained most of the archaeological artefacts, and a lower Mottisfont Formation. Results of specific note included recovery of artefacts demonstrating elements of ‘proto-Levallois’ technology from within the Belbin Gravel deposition. Fully developed Levallois technology was present across both the Belbin Gravel and the Mottisfont Formation at Dunbridge, the latter having an otherwise relatively sparse Palaeolithic content. Previously published OSL dating, supplemented by new data, has been combined with uplift modelling to suggest dates of MIS 9b and MIS 8, respectively, for these two gravels. This fits well with evidence from other sites in England and the near Continent for the timing of the earliest Levallois at around MIS 9. The results from the Dunbridge watching brief have demonstrated that this response provides a relatively cost effective method by which important scientific data can be salvaged from commercial quarrying.     

QuakeSim and the Solid Earth Research Virtual Observatory

We are developing simulation and analysis tools in order to develop a solid Earth Science framework for understanding and studying active tectonic and earthquake processes. The goal of QuakeSim and its extension, the Solid Earth Research Virtual Observatory (SERVO), is to study the physics of earthquakes using state-of-the-art modeling, data manipulation, and pattern recognition technologies. We are developing clearly defined accessible data formats and code protocols as inputs to simulations, which are adapted to high-performance computers. The solid Earth system is extremely complex and nonlinear, resulting in computationally intensive problems with millions of unknowns. With these tools it will be possible to construct the more complex models and simulations necessary to develop hazard assessment systems critical for reducing future losses from major earthquakes. We are using Web (Grid) service technology to demonstrate the assimilation of multiple distributed data sources (a typical data grid problem) into a major parallel high-performance computing earthquake forecasting code. Such a linkage of Geoinformatics with Geocomplexity demonstrates the value of the Solid Earth Research Virtual Observatory (SERVO) Grid concept, and advances Grid technology by building the first real-time large-scale data assimilation grid.     

iSERVO: Implementing the International Solid Earth Research Virtual Observatory by Integrating Computational Grid and Geographical Information Web Services

We describe the goals and initial implementation of the International Solid Earth Virtual Observatory (iSERVO). This system is built using a Web Services approach to Grid computing infrastructure and is accessed via a component-based Web portal user interface. We describe our implementations of services used by this system, including Geographical Information System (GIS)-based data grid services for accessing remote data repositories and job management services for controlling multiple execution steps. iSERVO is an example of a larger trend to build globally scalable scientific computing infrastructures using the Service Oriented Architecture approach. Adoption of this approach raises a number of research challenges in millisecond-latency message systems suitable for internet-enabled scientific applications. We review our research in these areas.     

The use of tracers to assess leakage from the sequestration of CO2 in a depleted oil reservoir,New Mexico,USA

Geological sequestration of CO₂ in depleted oil reservoirs is a potentially useful strategy for greenhouse gas management and can be combined with enhanced oil recovery. Development of methods to estimate CO₂ leakage rates is essential to assure that storage objectives are being met at sequestration facilities. Perfluorocarbon tracers (PFTs) were added as three 12 h slugs at about one week intervals during the injection of 2090 tons of CO₂ into the West Pearl Queen (WPQ) depleted oil formation, sequestration pilot study site located in SE New Mexico. The CO₂ was injected into the Permian Queen Formation. Leakage was monitored in soil–gas using a matrix of 40 capillary adsorbent tubes (CATs) left in the soil for periods ranging from days to months. The tracers, perfluoro-1,2-dimethylcyclohexane (PDCH), perfluorotrimethylcyclohexane (PTCH) and perfluorodimethylcyclobutane (PDCB), were analyzed using thermal desorption, and gas chromatography with electron capture detection. Monitoring was designed to look for immediate leakage, such as at the injection well bore and at nearby wells, and to develop the technology to estimate overall CO₂ leak rates based on the use of PFTs. Tracers were detected in soil–gas at the monitoring sites 50 m from the injection well within days of injection. Tracers continued to escape over the following years. Leakage appears to have emanated from the vicinity of the injection well in a radial pattern to about 100 m and in directional patterns to 300 m. Leakage rates were estimated for the 3 tracers from each of the 4 sets of CATs in place following the start of CO₂ injection. Leakage was fairly uniform during this period. As a first approximation, the CO₂ leak rate was estimated at about 0.0085% of the total CO₂ sequestered per annum.