“We used more than 20,000 THEMIS nighttime temperature images to generate the highest resolution surface property map of Mars ever created,” explained team member Dr Robin Fergason at the U.S. Geological Survey’s Astrogeology Science Center in Flagstaff, Arizona. As day and night alternate on Mars, loose, fine-grain materials such as sand and dust change temperature quickly and thus have low values of thermal inertia. Bedrock represents the other end of the thermal inertia range: because it cools off slowly at night and warms up slowly by day, it has a high thermal inertia.“Darker areas in the map are cooler at night, have a lower thermal inertia and likely contain fine particles, such as dust, silt or fine sand. The brighter regions are warmer, she explains, and have surfaces with higher thermal inertia. These consist perhaps of coarser sand, surface crusts, rock fragments, bedrock or combinations of these materials,” Dr Fergason said. A version of the map optimized for scientists is available at the U.S. Geological Survey.
“The map has an important practical side. NASA used THEMIS images to find safe landing sites for the Mars Exploration Rovers in 2004, and for Curiosity, the Mars Science Laboratory rover, in 2012,” Dr Fergason said. “THEMIS images are now helping NASA select a landing site for its next Mars rover in 2020.”
