- Press Release
- Nov 29, 2022
NASA Mars Odyssey THEMIS Image: Melas Chasma in IR Color
Context image credit: NASA/Mars Orbiter Laser Altimeter (MOLA) Team
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Full data on this image has now been released via the THEMIS Data Releases website.
This image shows two representations of the same infra-red image over Melas Chasma. On the left is a grayscale image showing surface temperature, and on the right is a false-color composite made from 3 individual THEMIS bands. The false-color image is colorized using a technique called decorrelation stretch (DCS), which emphasizes the spectral differences between the bands to highlight compositional variations.
There is a distinct purple/blue layer present in the northern wall of the Chasma. Although this layer likely has a composition different than the surrounding areas, it is difficult to interpret its specific composition due to the high variability of sunlit and shaded surfaces in this area, which cause a wide range of temperatures to be present within each pixel of the image. It is possible that this layer has a unique composition due to differences in the volcanic or sedimentary environment at the time that the rock formed, or it could be a layer of magma injected between two previously existing rock layers. Another possibility is that the wall is mostly covered by dust and debris, and this portion contains the only exposed bedrock. The light blue colors present in many other areas of the Chasma are due to water ice clouds.
[Source: ASU THEMIS Science Team]
Note: this THEMIS infrared image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.
Image Credit: NASA/JPL/Arizona State University
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