In-situ regolith instrumentation: Space Weathering and bulk density

Résumé: Two separate instrument techniques are discussed here for making in situ measurements of planetary regolith properties. The first is proposed to characterise the degree of impact and solar wind alteration to exposed regoliths on airless bodies. This <> changes the optical and magnetic properties of the soil, masking spectral properties measured from orbit. Multi-frequency measurements of magnetic susceptibility can be used to detect the sub-microscopic metallic iron responsible for these changes. Used together with other surface instrumentation, such as Mossbauer spectroscopy, such measurements provide vital ground truth in support of orbital measurements and assist the mapping of true quantitative mineralogy. The second technique discussed is the measurement of bulk density. As well as being of interest in its own right for both science and engineering purposes, this parameter is necessary for assessing planetary heat flux. The Heat flow and Physical Properties Package (HP3) originally proposed for the BepiColombo Mercury Surface Element has been funded by ESA for technology development and is approaching breadboard maturity. Delivered by a mole to a depth of several metres, HP3 measures the temperature gradient and thermal properties of the regolith using combined temperature sensors and heater and also measures a bulk density profile. The densitometer (DEN), developed at the Open University, uses a gamma-ray Compton backscatter technique and is described here. ------------------------------------------------------------------------ SEMINAIRES DE SAINT MAUR ------------------------------------------------------------------------