Neil Bowles

Abstract:

The retrieval of surface composition from IR measurements of airless bodies requires a model capable of computing the significant thermal gradients present in the top few hundred microns of the regolith. In this study we introduce a model which reproduces most of the features found in controlled experiments made in the simulated lunar environment emission chamber (SLEEC). Although the model presented here is forced by a lower boundary held at a fixed temperature, we conclude that a similar algorithm driven by solar illumination may be used as a forward model to retrieve composition, particle size and effective thermal conductivity from IR measurements of airless bodies. Copyright 2011 by the American Geophysical Union.

Abstract:

Accurate measurement of the temperature, composition and dynamics of Jupiter's atmosphere is one of the main scientific goals of ESA's and NASA's Outer Planet Mission proposals. Infrared remote sounding provides a powerful tool for achieving these objectives and was used by Voyager/IRIS and Cassini/CIRS, but is insensitive to some altitudes and gases. The sub-millimetre wavelength (terahertz) region of the electromagnetic spectrum, which has not been significantly exploited to date in the discipline of planetary science, provides unique spectral information over a range of atmospheric pressures and, when combined with infrared data, is a powerful in situ planetary atmospheric sounder. We will describe a novel low mass and low power consumption combined terahertz/IR instrument proposed for inclusion on the Jupiter Ganymede Orbiter that will greatly improve our understanding of the atmosphere of Jupiter. Through the combination of high spectral resolution 2.2THz spectroscopy (R=10⁶) and lowspectral resolution IR radiometry, the entire temperature profile of the Jovian atmosphere from 0.6 to 10^-3 bar can be evaluated (filling in the currently unmeasured levels between 0.1 and 0.01 bar). In addition, the tropospheric and stratospheric composition can be determined (especially water vapour) and observations of the Doppler shifting of sub-millimetre lines can also be used to measure horizontal wind speeds.

Abstract:

Diviner Lunar Radiometer Experiment surface-temperature maps reveal the existence of widespread surface and near-surface cryogenic regions that extend beyond the boundaries of persistent shadow. The Lunar Crater Observation and Sensing Satellite (LCROSS) struck one of the coldest of these regions, where subsurface temperatures are estimated to be 38 kelvin. Large areas of the lunar polar regions are currently cold enough to cold-trap water ice as well as a range of both more volatile and less volatile species. The diverse mixture of water and high-volatility compounds detected in the LCROSS ejecta plume is strong evidence for the impact delivery and cold-trapping of volatiles derived from primitive outer solar system bodies.

Abstract:

We obtained direct global measurements of the lunar surface using multispectral thermal emission mapping with the Lunar Reconnaissance Orbiter Diviner Lunar Radiometer Experiment. Most lunar terrains have spectral signatures that are consistent with known lunar anorthosite and basalt compositions. However, the data have also revealed the presence of highly evolved, silica-rich lunar soils in kilometer-scale and larger exposures, expanded the compositional range of the anorthosites that dominate the lunar crust, and shown that pristine lunar mantle is not exposed at the lunar surface at the kilometer scale. Together, these observations provide compelling evidence that the Moon is a complex body that has experienced a diverse set of igneous processes.