- Press Release
- Oct 5, 2022
NASA Mars Odyssey THEMIS Image: Meridiani Crater in Day and Night
Context image credit: NASA/Mars Orbiter Laser Altimeter (MOLA) Team
[ Find on map: CGI version ]
Full data on this image has now been released via the THEMIS Data Releases website.
This pair of images shows crater ejecta in the Terra Meridiani region.
Day/Night Infrared Pairs
The image pairs presented focus on a single surface feature as seen
in both the daytime and nighttime by the infrared THEMIS camera.
The nighttime image (right) has been rotated 180 degrees to place north at
Infrared image interpretation
Infrared images taken during the daytime exhibit both the morphological and
thermophysical properties of the surface of Mars. Morphologic details are
visible due to the effect of sun-facing slopes receiving more energy than
antisun-facing slopes. This creates a warm (bright) slope and cool (dark) slope
appearance that mimics the light and shadows of a visible wavelength image.
Thermophysical properties are seen in that dust heats up more quickly than
rocks. Thus dusty areas are bright and rocky areas are dark.
Infrared images taken during the nighttime exhibit only the thermophysical
properties of the surface of Mars. The effect of sun-facing versus non-sun-facing
energy dissipates quickly at night. Thermophysical effects dominate as different
surfaces cool at different rates through the nighttime hours. Rocks cool
slowly, and are therefore relatively bright at night (remember that rocks are
dark during the day). Dust and other fine grained materials cool very quickly
and are dark in nighttime infrared images.
[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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