Paper Session I-A - Dielectric Properties of Martian Soil Simulant

NASA’s Viking and Mars Pathfinder missions each used onboard instruments to determine the composition of the Martian soil at their respective landing sites. Those findings led to the development of a Martian soil simulant (JSC Mars-1) at NASA Johnson Space Center. However, in spite of the compositional studies conducted during those previous missions, no direct measurements were ever made of the dielectric properties of the Martian soil. Recently, instrumentation was developed at NASA Kennedy Space Center that enables investigations of the dielectric properties of granular materials to be conducted, including studies of Martian soil simulant. In the present study, a three-electrode system was used to measure the frequency response to an applied sinusoidal voltage of finely ground Martian soil simulant that was placed in a dry, low-vacuum environment. The data is shown to support a simple model of the granular system in which the resistances and capacitances of individual particles are connected in series by the resistance and capacitance of interparticle contacts

Uso de SIG´S no delineamento de zonas de manejo para uso agrícola.

Este trabalho trata da utilização do sistema de informação geográfica (SIG) e aplicativos geoestatísticos para definição de sub-áreas homogêneas em um sítio específico, tendo como referência um pivot central de 38 ha instalado na Embrapa Milho e Sorgo em LEd, fase cerrado, 19"28 '03" latitude S, 44°10'37" longitude W, com declive de cerca de 5%, aqui denominado pivot 3. Foi utilizada a base cartográfica da Embrapa Milho e Sorgo, na escala de 1:10.000, e coleta direta de dados, com o Global Positioning System (GPS). Foram utilizados na análise, dados de produtividade de milho dos anos agrícola 1999/00 e 2000/01 (metade do pivot) e soja do ano agrícola 2000/01 (metade do pivot), fertilidade de solos, condutividade elétrica, altitude. O processo de análise incluiu tratamento geoestatístico, tratamento espacial e interpretação visual de imagem de satélite Landsat5, como balizador dos resultados aferídos. Pode -se concluir que o Modelo FuzMe mostrou ser eficiente na definição das quatro zonas de manejo pois é um método de resposta rápida aos agrupamentos similares. O refinamento das informações poderá oferecer subsídios ao incremento de eficiência no manejo agrícola

Exploring atmospheric radon with airborne gamma-ray spectroscopy

$^{222}$Rn is a noble radioactive gas produced along the $^{238}$U decay chain, which is present in the majority of soils and rocks. As $^{222}$Rn is the most relevant source of natural background radiation, understanding its distribution in the environment is of great concern for investigating the health impacts of low-level radioactivity and for supporting regulation of human exposure to ionizing radiation in modern society. At the same time, $^{222}$Rn is a widespread atmospheric tracer whose spatial distribution is generally used as a proxy for climate and pollution studies. Airborne gamma-ray spectroscopy (AGRS) always treated $^{222}$Rn as a source of background since it affects the indirect estimate of equivalent $^{238}$U concentration. In this work the AGRS method is used for the first time for quantifying the presence of $^{222}$Rn in the atmosphere and assessing its vertical profile. High statistics radiometric data acquired during an offshore survey are fitted as a superposition of a constant component due to the experimental setup background radioactivity plus a height dependent contribution due to cosmic radiation and atmospheric $^{222}$Rn. The refined statistical analysis provides not only a conclusive evidence of AGRS $^{222}$Rn detection but also a (0.96 $\pm$ 0.07) Bq/m$^{3}$ $^{222}$Rn concentration and a (1318 $\pm$ 22) m atmospheric layer depth fully compatible with literature data.Comment: 17 pages, 8 figures, 2 table

Paper Session II-C - Detection of Water in Martian Soil

The mineral composition of the Martian soil was previously characterized during NASA\u27s two Viking missions, and also on the Mars Pathfinder mission. The recent NASA MER missions will also contribute to our understanding of the composition of the Martian soil, and they will also look for evidence to indicate the presence of water in the soil at some time in the distant past. While the ongoing Mars Glob al Surveyor orbiter mission has provided (indirect) evidence for the presence of water on Mars, there have not been any direct measurements of water in the Martian soil by any lander mission. We will describe a possible method that may be used to directly detect water in the Martian soil. We will present data obtained using an instrument that we developed at NASA Kennedy Space Center to measure the dielectric properties of JSC Mars- I Martian soil simulant under dry and moist conditions, and show that this is a direct method that can be used to detect the presence of water in soil