On the exploitation of differential aerodynamic lift and drag as a means to control satellite formation flight

For a satellite formation to maintain its intended design despite present perturbations (formation keeping), to change the formation design (reconfiguration) or to perform a rendezvous maneuver, control forces need to be generated. To do so, chemical and/or electric thrusters are currently the methods of choice. However, their utilization has detrimental effects on small satellites’ limited mass, volume and power budgets. Since the mid-80s, the potential of using differential drag as a means of propellant-less source of control for satellite formation flight is actively researched. This method consists of varying the aerodynamic drag experienced by different spacecraft, thus generating differential accelerations between them. Its main disadvantage, that its controllability is mainly limited to the in-plain relative motion, can be overcome using differential lift as a means to control the out-of-plane motion. Due to its promising benefits, a variety of studies from researchers around the world have enhanced the state-of-the-art over the past decades which results in a multitude of available literature. In this paper, an extensive literature review of the efforts which led to the current state-of-the-art of different lift and drag-based satellite formation control is presented. Based on the insights gained during the review process, key knowledge gaps that need to be addressed in the field of differential lift to enhance the current state-of-the-art are revealed and discussed. In closer detail, the interdependence between the feasibility domain/the maneuver time and increased differential lift forces achieved using advanced satellite surface materials promoting quasi-specular or specular reflection, as currently being developed in the course of the DISCOVERER project, is discussed

Rapid response to the earthquake emergency of May 2012 in the Po Plain, northern Italy

No abstrac

Bristol Bay Subsistence Harvest and Sociocultural Systems Inventory

In 1975, in response to a lack of published information on which to base environmental impact statements, the Minerals Management Service (MMS) began to sponsor a series of social and economic studies in a variety of offshore areas. The goal of these studies is to provide information necessary in the development of accurate and defensible environmental assessments and to make possible the monitoring of environmental effects from OCS development, should such effects occur. Because harvests of naturally-occurring, renewable (wild) resources are important to rural Alaskan communities, much work has focused on subsistence issues. The need for Bristol Bay subsistence-harvest and sociocultural information had been identified in several MMS Alaska Regional Studies Plans. The Alaska Department of Fish and Game (ADF&G), Division of Subsistence, as a result of an FY-1988 study, supplied MMS with a computerized data base and technical papers from baseline subsistence studies they had conducted in Bristol Bay communities beginning in 1980. The general purpose of this study was to describe and analyze the harvest and uses of wild resources for the Bristol Bay region. Specific study objectives were: 1) development of a typology of subregions within Bristol Bay based on multivariate analysis of subsistence harvesting and processing; 2) examination of the ethnographic meanings and context of subsistence; and, 3) analysis of the key political, economic, social and cultural factors that affect subsistence pursuits

Feasibility study on earthquake early warning application to schools: the example of the ITIS ‘E. Majorana', Somma Vesuviana, Naples (Italy)

Feasibility study on earthquake early warning application to schools: the example of the ITIS ‘E. Majorana', Somma Vesuviana, Naples (Italy