Lunar Exploration Orbiter (LEO): Providing a Globally Covered, Highly Resolved, Integrated Geological, Geochemical and Gephysical Data Base of the Moon

The German initiative for the Lunar Exploration Orbiter (LEO) originated from the national conference “Exploration of our Solar System”, held in Dresden in November 2006. Major result of this conference was that the Moon is of high interest for the scientific community for various reasons, it is affordable to perform an orbiting mission to Moon and it insures technological and scientific progress necessary to assist further exploration activities of our Solar System. Based on scientific proposals elaborated by 50 German scientists in January 2007, a preliminary payload of 12 instruments was defined. Further analysis were initated by DLR in the frame of two industry contracts, to perform a phase-zero mission definition. The Moon, our next neighbour in the Solar System is the first choice to learn, how to work and live without the chance of immediate support from earth and to get prepared for further and farther exploration missions. We have to improve our scientific knowledge base with respect to the Moon applying modern and state of the art research tools and methods. LEO is planed to be launched in 2012 and shall orbit the Moon for about four years in a low altitude orbit

Hydraulic conductivity estimation from induced polarisation data at the field scale - the Krauthausen case history

Recently, encouraging results have been obtained to estimate hydraulic conductivity in unconsolidated sediments from induced polarisation (IP) measurements. The work focussed on laboratory experiments in order to establish semi-empirical relationships between complex electrical conductivity and hydraulic parameters. Although field studies are certainly important to evaluate the feasibility of the method in practice, only a limited number of case histories have been reported. We carried out an IP survey at the Krauthausen hydrogeological test site in Germany. Multifrequency data were recorded along two profiles with a dipole-dipole configuration and 2 in electrode spacing. The data were inverted with a 2-D inversion code to obtain images of conductivity magnitude and phase for each frequency. We used a novel focussing regularisation scheme that does not suppress sharp boundaries and yields realistic images of the subsurface. The gross structural features compare well with the known lithology, which consists of an approx. 9 in thick sand/gravel aquifer over fine sands and a thin clay layer which constitutes the base at approx. I I in depth. From the complex electrical conductivity distribution we calculate hydraulic conductivity estimates using the empirical equations suggested by Bbmer et al. [Borner, F. D., Schopper J. R., Weller, A., 1996. Evaluation of transport and storage properties in the soil and groundwater zone from induced polarisation measurements. Geophys. Prosp. 44, 583-601] and by Slater and Lesmes [Slater, L. D., Lesmes, D. P., 2002a. Electric hydraulic relationships observed for unconsolidated sediments. Water Res. Research, 3 8 (10), doi:10.1029/2001WR001075] and compare the results with values obtained from grain size data at two boreholes. The Bbmer model yields hydraulic conductivities in the same order of magnitude as the grain size data, whereas the Slater and Lesmes model substantially underestimates hydraulic conductivities. We also compare the specific inner surface estimated from our IP data with values obtained from BET measurements at the two borehole locations. In this case, we observe a reasonable agreement with both the Borner and the Slater and Lesmes equations. Our results constitute an encouraging example where reasonable estimates of hydraulic parameters are obtained at the field scale. (C) 2006 Elsevier B.V. All rights reserved