The PLATO mission

PLATO (PLAnetary Transits and Oscillations of stars) is ESA’s M3 mission designed to detect and characterise extrasolar planets and perform asteroseismic monitoring of a large number of stars. PLATO will detect small planets (down to <2R ) around bright stars (<11 mag), including terrestrial planets in the habitable zone of solar-like stars. With the complement of radial velocity observations from the ground, planets will be characterised for their radius, mass, and age with high accuracy (5%, 10%, 10% for an Earth-Sun combination respectively). PLATO will provide us with a large-scale catalogue of well-characterised small planets up to intermediate orbital periods, relevant for a meaningful comparison to planet formation theories and to better understand planet evolution. It will make possible comparative exoplanetology to place our Solar System planets in a broader context. In parallel, PLATO will study (host) stars using asteroseismology, allowing us to determine the stellar properties with high accuracy, substantially enhancing our knowledge of stellar structure and evolution. The payload instrument consists of 26 cameras with 12cm aperture each. For at least four years, the mission will perform high-precision photometric measurements. Here we review the science objectives, present PLATO‘s target samples and fields, provide an overview of expected core science performance as well as a description of the instrument and the mission profile towards the end of the serial production of the flight cameras. PLATO is scheduled for a launch date end 2026. This overview therefore provides a summary of the mission to the community in preparation of the upcoming operational phases

Lateral stability of pipelines in clay. Presented at: 11 annu. offshore technology conference Houston, TX (USA) 30 Apr. 1979

p. 1025-1034.The material presented in this paper is derived from a laboratory and field investigation using model pipelines in cohesive soils. The field investigation, sponsored by Shell Development Company, was carried out in Harris County, Texas, near Galveston Bay. The study was accomplished using 2.875 and 4.50 inch diameter pipes which were weighted with steel rods to obtain different specific gravities of pipe. A followup investigation was conducted in the laboratory using pipe diameters of 1.50 and 3.00 inches. The model pipes were also filled with ballast but the pipe specific gravity was not varied. The laboratory investigation was conducted to extend the results of the field work in a controlled environment using kaolin clay. The parameters varied in the laboratory investigation included depth of embedment, pipe diameter and rate of displacement. The soil type, water content and shear strength were not varied. Based on both sets of studies, a modified theoretical model was developed to calculate the maximum values of resistance based upon the theory of plasticity using the limit analysis techniques. A relationship between the depth-to-diameter ratio of the pipeline and the maximum resistance developed against lateral movement in the soil is presented. Conclusions are drawn with respect to the effect of the diameter of the pipe, pipe weight, and the rate of displacement on the soil resistance developed. Finally, recommendations are made for further work in this field.http://gbic.tamug.edu/request.ht