The ASTER (Advanced Spaceborne Thermal Emission and Reflection radiometer) is one of five state-of-art instrument sensors aboard satellite Terra (originally known as Earth Observing System EOS AM-1) launched 1999. This was the first launch in NASA’s Earth Observing System program. Terra carries multispectral imagers, radiation budget instrument, detector to measure CO and methane pollution and an instrument to study cloud top and vegetation properties. The orbital parameters of Terra are similar to Landsat 7’s so the sensor suite on both satellites can act in a supplementary arrangement.

ASTER is a Japanese built 14 channel sensor with the ability of backward viewing for along-track stereoscopic observation. Channels are arranged around atmospheric windows in the visible and thermal parts of electromagnetic spectrum. Compared with Landsat, ASTER has a better spectral resolution in both the mid infrared (sometimes referred to as the ‘short wave infrared’) and thermal infrared spectrums. The significant advantage is a better (12-bits) radiometric resolution (dynamic range) in the thermal infrared to enable the precise measurement of surface temperatures.

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