Global Nighttime Temperatures

Figure 1: Global Nighttime Temperatures

This image shows the nighttime (2 AM) temperature of the Martian surface as measured by the Thermal Emission Spectrometer (TES) instrument on the Mars Global Surveyor. The data were acquired during the first 500 orbits of the MGS mapping mission. The coldest temperatures (shown in purple) are -120C and the warmest temperatures (white) are -65C. The pattern of nighttime temperature in the equatorial region indicates variations in the particle size of the surface materials.

The coldest regions are areas of very fine (dust) grains, while the warmest regions are areas of coarse sand, gravel, and rocks. Valles Marineris (~-10S, 30-90W) and the channels leading into Acidalia Planitia and the Pathfinder landing site (5-20N; 20-45W) are clearly visible as regions of warm (sand and rock) material. The cold regions in the south mark the edge of the south polar cap. The pattern of nighttime temperatures observed by TES agrees well with the thermal inertia maps made by the Viking Infrared Thermal Mapper experiment, but the TES data shown here are at significantly higher spatial resolution (15 km versus 60 km).

Figure 2: Hemispheric View

This image shows the nighttime (2AM) temperatures measured by the Thermal Emission Spectrometer (TES) instrument on the Mars Global Surveyor wrapped on to a globe. The coldest temperatures (shown in purple) are -120C and the warmest temperatures (white) are -65C.

The view is centered on Isidis Planitia (15N, 270W), which is covered with warm material, indicating a sandy and rocky surface. The small, cold (blue) circular region to the right is the Elysium volcanoes, which are covered in dust that cools off rapidly at night. At this season the north polar region is in full sunlight as is relatively warm at night. It is winter in the southern hemisphere and the temperatures are extremely low (~-120C).

The TES instrument was built by Santa Barbara Remote Sensing and is operated by Philip R. Christensen, of Arizona State University, Tempe, AZ. The MGS mission is managed for NASA by the Jet Propulsion Laboratory, Pasadena CA.

Contact: Phil Christensen, Arizona State University; (480) 965-1790

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