Earth observation data archiving in the USA and Europe

The growing number of Earth observation satellites are producing exponential increases in the amount of data produced. These data sets contain valuable information on the state of the environment to accurately monitor and predict the impact of global change. Global change investigations require access to long-term data. This paper is a review of the current archiving practices of NOAA, NASA, SPOT, ESA and the DLR. It is demonstrated that despite recognition at a regional and organisational level of the importance of data archiving much work remains to be done. Funding responsibility is identified as a particularly problematic area of data archiving: it is an issue along with the need for easy accessibility and adequate metadata that will need to be resolved to ensure that future generations have access to adequate Earth observation data archives.     

Fuel mass penalty due to generators and fuel cells as energy source of the all-electric aircraft

The paper presents the results of an assessment of the fuel mass penalty due to generators and fuel cell systems. Based on the simulation tool SysFuel, fuel mass penalties for different mission ranges and fuel cell architectures are calculated and compared to a conventional reference architecture. Different fuel cell architectures using ram air or cabin exhaust air and different options of energy recovery are considered. As a result of the studies, target values are presented for the mass to power ratio of fuel cell systems to achieve fuel mass reductions compared to conventional generator and auxiliary power unit systems.     

European perspectives on trends in public sector Earth observation data policies

The growing number of Earth observation satellites are producing ever increasing amounts of data. These data sets require adequate management to be widely exploited and to ensure preservation of what is a valuable information resource. Many Earth observation organisations have formulated or are developing policies related to how data are managed and distributed which encompass issues such as property rights, access and price of the data, exclusive data use and data archiving. European Earth observation is gaining more prominence in these developing policy issues. This paper is a review, from a largely European perspective, of current Earth observation data policies in operation by various public sector international, regional and national organisations in both the data providing and data user sectors. It will be demonstrated that certain trends exist between the various data policies but that differences in position are present in some key areas which may need to be reconciled in order for the Earth observation sector to reach maturity.     

On the stability of the track of the space elevator

A string moving with geostationary angular velocity in its radial relative equilibrium configuration around the Earth, reaching from the surface of the Earth far beyond the geostationary height, could be used as track for an Earth to space elevator. This is an old dream of mankind, originating about 100 years ago in Russia. Besides the question of feasibility from a technological point of view also the question concerning the stability of such a configuration has not yet been completely solved. Under the assumption that a proper material (carbon nanotubes) is available, making the connection possible technologically, we address the question of existence and stability of the radial relative equilibrium of a tapered string on a circular geosynchronous trajectory around the Earth, reaching from the surface of the Earth far beyond the geostationary height.     

Pricing policy and legal issues: 6th and 7th EOPOLE workshops

The following report presents the main conclusions of the sixth and seventh EOPOLE workshops, held in Hydra, Greece, 3–4 May and Leiden, the Netherlands, 3–5 July 2000, respectively. The objectives of the first workshop were to evaluate different approaches to pricing policy and to assess how new developments in Earth observation and information technology are having an impact on Earth observation data pricing policy. Those of the second were to assess the constraints that legal frameworks impose on Earth observation and to explore ways in which they can be used to its advantage.     

On biogenicity criteria for endolithic microborings on early Earth and beyond

Micron-sized cavities created by the actions of rock-etching microorganisms known as euendoliths are explored as a biosignature for life on early Earth and perhaps Mars. Rock-dwelling organisms can tolerate extreme environmental stresses and are excellent candidates for the colonization of early Earth and planetary surfaces. Here, we give a brief overview of the fossil record of euendoliths in both sedimentary and volcanic rocks. We then review the current understanding of the controls upon the distribution of euendolithic microborings and use these to propose three lines of approach for testing their biogenicity: first, a geological setting that demonstrates a syngenetic origin for the euendolithic microborings; second, microboring morphologies and distributions that are suggestive of biogenic behavior and distinct from ambient inclusion trails; and third, elemental and isotopic evidence suggestive of biological processing. We use these criteria and the fossil record of terrestrial euendoliths to outline potential environments and techniques to search for endolithic microborings on Mars.