For the first time since the Viking Mars mission of the 1970s, which ended more than a generation ago, scientists will soon begin systematic observations of Mars from orbit at times of day around local sunrise and sunset. The instrument they will use is the Thermal Emission Imaging System (THEMIS) camera, designed at
The new approach is a result of
"We don't know exactly what we'll find when we get to an orbit where we see Mars just after sunrise," says
THEMIS is a multi-band camera that images Mars in nine infrared (heat-sensitive) "colors" and five visible ones. It was launched on Mars Odyssey in
Morning and evening on Mars
Besides revealing landscapes in sharp relief, thanks to the low sun angle, the new orbital time of day for THEMIS promises to let scientists explore frosts, ground fogs, early morning clouds and hazes, and other transient atmosphere-related features that usually vanish as the Martian day goes on.
"We know that in places, carbon dioxide frost forms overnight," says Christensen. "And then it sublimates immediately after sunrise. What would this process look like in action? How would it behave? We've never observed this kind of phenomenon directly."
He notes that the Martian atmosphere is more variable than scientists have appreciated in the past.
"We can look for seasonal differences," says Christensen. "Are fogs more common in winter or spring? Do they vary from day to day? From one part of the year to another? From year to year? We'll check it out."
In addition, THEMIS will measure surface temperatures at thousands of locations. These observations can yield insight about materials in the ground and about temperature-driven processes. These include warm-season flows of water or brine seen on some slopes, and gas-and-sand geysers fed by spring thawing of carbon dioxide ice near Mars'
"We're teaching an old spacecraft new tricks," says Odyssey project scientist
After Mars Odyssey reaches its intended orbit of
"Mars is a dynamic world," says Christensen. "And for a generation, we've not been positioned to explore this part of it so thoroughly."
TNS 30TagarumaMar-140213-4636670 30TagarumaMar
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