ASTER images can include measurements made in three different spectral groups, visible and near-infrared (VNIR), short-wave infrared (SWIR), and thermal infrared (TIR). Several of the ASTER bands are designed specifically to enhance separation of geologic units, with narrower spectral bands than Landsat 7 ETM (and the Landsat 8 satellite that should be launched in the next few months). ASTER includes six bands in the thermal infrared that allows the detection of variations in thermal emissivity that can be helpful for separating some minerals. The ASTER images acquired after August 2008 do not have the SWIR measurements but do have the VNIR and TIR measurements. See http://asterweb.jpl.nasa.gov/ for more information on ASTER.

The Landsat 7 ETM+ and Landsat 4 & 5 TM instruments are similar except for a 15 m pan-chromatic band that was added on Landsat 7. There are 7 bands in the visible, near-infrared, short-wave infrared and thermal infrared for both ETM+ and TM. There is only one wide band in the thermal IR. As Benjamin noted, the Landsat 7 ETM+ instrument has degraded imagery since 2003, but there is data acquired by Landsat 5 TM until 2012 with full coverage. See http://landsat.usgs.gov/index.php for more information on the Landsat series.

ASTER has 15 bands whereas Landsat ETM+ has 8 bands. The short wave infrared ASTER bands are 30 meter resolution, the same as most of the Landsat bands. I would use ASTER for mineral prospecting rather than Landsat because of the tighter band grouping and use of additional bands even though you'll end up using bands with 30 meter resolution. You'll have more band combinations available. For modern imagery, ASTER is scan line corrected. The Landsat ETM+ scan line corrector broke in 2003.

ASTER images can include measurements made in three different spectral groups, visible and near-infrared (VNIR), short-wave infrared (SWIR), and thermal infrared (TIR). Several of the ASTER bands are designed specifically to enhance separation of geologic units, with narrower spectral bands than Landsat 7 ETM (and the Landsat 8 satellite that should be launched in the next few months). ASTER includes six bands in the thermal infrared that allows the detection of variations in thermal emissivity that can be helpful for separating some minerals. The ASTER images acquired after August 2008 do not have the SWIR measurements but do have the VNIR and TIR measurements. See http://asterweb.jpl.nasa.gov/ for more information on ASTER.

The Landsat 7 ETM+ and Landsat 4 & 5 TM instruments are similar except for a 15 m pan-chromatic band that was added on Landsat 7. There are 7 bands in the visible, near-infrared, short-wave infrared and thermal infrared for both ETM+ and TM. There is only one wide band in the thermal IR. As Benjamin noted, the Landsat 7 ETM+ instrument has degraded imagery since 2003, but there is data acquired by Landsat 5 TM until 2012 with full coverage. See http://landsat.usgs.gov/index.php for more information on the Landsat series.

Landsat 8 TIRS is important also because mission continuity of Landsat until 2018 include a new generation prototype..

low temperature can be modeled using physical laws...