To calculate the diffusive flux of a condensable gas through a geologically reasonable soil, an accurate model of both the pore-size distribution and pore structure must be used. Unfortunately, even some of the best models for describing diffusion through soils with broad pore-size distributions fail miserably when applied to diffusion problems that involve condensation. One particular area of interest is aqueous alteration of materials, which has played a large role in the development of some asteroids and possibly comets as well. Determining the porosity of a sample is important in studying aqueous alteration. However, these methods are not applicable to small samples of IDPs and most meteorites.
Much work remains to be done.
Relatively few IDPs have been examined, and there is a paucity of data for carbonaceous chondrites. This summer we will continue our work on IDPs and extend it to carbonaceous and ordinary chondrites on samples now in hand. With the results of this summer's work in hand, we should be able to proceed with three-dimensional numerical modeling of the fluid flow and attendant alteration within hydrous asteroids. Paul Schenk, Lunar and Planetary Institute Io is the most volcanically active object in the solar system, yet we know little about even the gross composition of the lavas that cover the vast majority of its surface. Numerous volcanic pits, or calderas, dot the surface.