Major spin-offs from NASA's multi- and hyper spectral imaging remote sensing technology developed for Earth resources monitoring, are creative techniques that combine and integrate spectral with spatial methods. Such techniques are finding use in medicine, agriculture, manufacturing, forensics, and an e er expanding list of other applications. Many such applications are easier to implement using a sensor design different from the pushbroom or whiskbroom air- or space-borne counterparts. This need is met by using a variety of electronically tunable filters that are mounted in front of a monochrome camera to produce a stack of images at a sequence of wavelengths, forming the familiar 'image cube'. The combined spectral/spatial analysis offered by such image cubes takes advantage of tools borrowed form spatial image processing, chemometrics and specifically spectroscopy, and new custom exploitation tools developed specifically for these applications. Imaging spectroscopy is particularly useful for non homogeneous samples or scenes. examples include spatial classification based on spectral signatures, use of spectral libraries for material identification, mixture composition analysis, plume detection, etc. This paper reviews available tunable filters ,system design considerations, general analysis techniques for retrieving the intrinsic scene properties from the measurements, and applications and examples.

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Imaging spectroscopy using tunable filters: a review

[1] Against a backdrop of intensive exploration of the Martian surface environment, intended to lead to human exploration, some aspects of the modern climate and the meteorology of Mars remain relatively unexplored. In particular, there is a need for detailed measurements of the vertical profiles of atmospheric temperature, water vapor, dust, and condensates to understand the intricately related processes upon which the surface conditions, and those encountered during descent by landers, depend. The most important of these missing data are accurate and extensive temperature measurements with high vertical resolution. The Mars Climate Sounder experiment on the 2005 Mars Reconnaissance Orbiter, described here, is the latest attempt to characterize the Martian atmosphere with the sort of coverage and precision achieved by terrestrial weather satellites. If successful, it is expected to lead to corresponding improvements in our understanding of meteorological phenomena and to enable improved general circulation models of the Martian atmosphere for climate studies on a range of timescales.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2006JE002790

Mars Climate Sounder: An investigation of thermal and water vapor structure, dust and condensate distributions in the atmosphere, and energy balance of the polar regions

The Diviner Lunar Radiometer Experiment on NASA’s Lunar Reconnaissance Orbiter will be the first instrument to systematically map the global thermal state of the Moon and its diurnal and seasonal variability. Diviner will measure reflected solar and emitted infrared radiation in nine spectral channels with wavelengths ranging from 0.3 to 400 microns. The resulting measurements will enable characterization of the lunar thermal environment, mapping surface properties such as thermal inertia, rock abundance and silicate mineralogy, and determination of the locations and temperatures of volatile cold traps in the lunar polar regions.

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The Lunar Reconnaissance Orbiter Diviner Lunar Radiometer Experiment

The possible role of the north residual cap in the current Martian water cycle was examined using models to assess the ability of the cap to supply water to the atmosphere and the ability of the atmospheric circulation to transport it out of the polar regions to low northern latitudes. Results indicate that rather extreme circumstances would be required for the cap to provide all of the observed increase in atmospheric water, such as a combination of high surface winds, low cap emissivities, or substantial evaporation from dark material. But even if these conditions could be met, the high-latitude circulation is too localized in scale to move much water vapor out of the polar environment. Both the present calculations and the data from the Viking's Mars Atmospheric Water Detection Experiment show that about two thirds of the water appearing in the Martian northern hemisphere during summer must be supplied by other sources. It is suggested that the additional source is water desorbing from the nonpolar regolith.

Sublimation and transport of water from the north residual polar cap on Mars

Current understanding of weather, climate and global atmospheric circulation on Mars is incomplete, in particular at altitudes above about 30 km. General circulation models for Mars [1,2,3,4,5,6] are similar to those developed for weather and climate forecasting on Earth and require more martian observations to allow testing and model improvements. However, the available measurements of martian atmospheric temperatures, winds, water vapour and airborne dust are generally restricted to the region close to the surface and lack the vertical resolution and global coverage that is necessary to shed light on the dynamics of Mars' middle atmosphere at altitudes between 30 and 80 km (ref. 7). Here we report high-resolution observations from the Mars Climate Sounder instrument [8] on the Mars Reconnaissance Orbiter [9]. These observations show an intense warming of the middle atmosphere over the south polar region in winter that is at least 10–20 K warmer than predicted by current model simulations. To explain this finding, we suggest that the atmospheric downwelling circulation over the pole, which is part of the equator-to-pole Hadley circulation, may be as much as 50% more vigorous than expected, with consequences for the cycles of water, dust and CO2 that regulate the present-day climate on Mars.

Intense polar temperature inversion in the middle atmosphere on Mars

The study of the atmosphere and climate of Mars will soon be advanced considerably by the Mars Observer mission. This paper describes the atmospheric sounder for this mission and how it will measure key Martian atmospheric parameters using IR gas correlation and filter radiometry. The instrument now under development will provide high-resolution vertical profiles of atmospheric temperature, pressure, water vapor, dust, and clouds using limb sounding techniques as well as nadir observations of surface thermal properties and polar radiative balance.

Dj J. Diner

Papers

Remote sensing of the atmosphere of Mars using infrared pressure modulation and filter radiometry.