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MARS ODYSSEY October 24, 2001. Thermal Emission Imaging System (THEMIS). Visible Imaging System Visible-light images with 18 meters per pixel resolution Infrared Imaging System Infrared data set with 100 meters per pixel resolution.
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MARS ODYSSEY October 24, 2001
Thermal Emission Imaging System (THEMIS) • Visible Imaging System • Visible-light images with 18 meters per pixel resolution • Infrared Imaging System • Infrared data set with 100 meters per pixel resolution
Reviewing features on Mars as seen in THEMIS visible images and MOLA shaded relief context images
THEMIS Visible Image Most THEMIS visible images are ~18 km across CONTEXT images appear to have the sun shining from the right Context Image: MOLA Shaded Relief THEMIS visible images are taken during the afternoon and the sun is shining from the left -19N, 173E
THEMIS Visible Image Context Image 2N, 237E
THEMIS Visible Image: Caldera Context Image 2N, 237E
THEMIS Visible Image Context Image -20N, 240E
THEMIS Visible Image: Lava Flow Context Image -20N, 240E
THEMIS Visible Image Context Image Coprates Chasma -14N, 307E
THEMIS Visible Image: Canyon plateau, landslides and floor Context Image Coprates Chasma -14N, 307E
Landslide closeupsTHEMIS visible images Melas Chasma -9N, 282E Ius Chasma -7N, 275E
Candor Chasma -7N, 290E Layers within Valles Marineris
THEMIS Visible Image Context Image -47N, 19E
THEMIS Visible Image: Sand Dunes Context Image -47N, 19E
THEMIS Visible Image Context Image 55N, 190E
THEMIS Visible Image: Splosh Crater with central peak and slumps Central Peak Slumps Context Image 55N, 190E
Hale Crater -35N, 324E Gullies found in crater walls
THEMIS Visible Image Context Image 22N, 126E
THEMIS Visible Image: Channel Context Image 22N, 126E
THEMIS Visible Image Context Image 18N, 329E
THEMIS Visible Image: Streamlined Islands Context Image 18N, 329E
THEMIS Visible Image Context Image -3N, 331E
THEMIS Visible Image: Chaos Terrain Context Image -3N, 331E
THEMIS Visible Image Context Image 25N, 255E
THEMIS Visible Image: Graben/Fractures Context Image 25N, 255E
THEMIS Visible Image Context Image -15N, 175E
THEMIS Visible Image: Dust Devil Tracks Context Image -15N, 175E
THEMIS Visible Image Context Image -5N, 200E
THEMIS Visible Image: Yardangs Context Image -5N, 200E
Behavior of Light • Reflect • Transmit • Absorb • Emit • In the visible, we are seeing reflected light • In the infrared, we are detecting emitted energy
Infrared Energy/Light • Primarily thought of as heat (thermal radiation) • Is part of the EM spectrum • Infrared energy is just beyond the red portion of the visible light spectrum – we can not see infrared energy with our eyes • Any object that has a temperature above absolute zero (~-273C or ~-460F) radiates in the infrared • Just about everything emits energy in the infrared – Everything glows!
ASU’s IR Camera • Gray-scale not color • Everything is relative! • Hot = Bright • Cold = Dark
Heating Effects • Sunlight versus shadow • Black versus white (Albedo) • What would you rather stand on: • Black asphalt parking lot • White concrete sidewalk • Albedo: A measure of how much light is being reflected • Dark colored material: reflects little light, absorbs a lot of light = low albedo • Light colored material: reflects a lot of light, absorbs little light = high albedo
Heating Effects Heating Effect Visible Day IR Night IR Sunlight High Low Albedo High Low TI High Low
Shadow Mapping Activity: Shadow and Sun Effects Materials Needed: -Notebook -IR Thermometers -Pencil -Colored pencils
Shadow Mapping Activity: Shadow and Sun Effects • Find an object which is casting a large shadow and will be in the sunlight for most of the day. • Record the current time, and sketch (as seen from above) the shadow cast by the object. Be sure to indicate which way is north on sketch. • Using the IR thermometer, measure the temperature of the object and the surrounding ground at the points indicated in the sample drawing. • Create a temperature scale and color your temperature map.
Temperature in Black and White Activity: Albedo Effects Materials Needed: -Notebook -IR Thermometers -Black and white albedo samples -Stopwatch -Colored pencils
Heating Effects Heating Effect Visible Day IR Night IR Sunlight High Low Albedo High Low TI High Low
Heating Effects Heating Effect Visible Day IR Night IR Sunlight High Bright Hot N/E Low Dark Cold N/E Albedo High Bright Cold N/E Low Dark Hot N/E TI High Low
Thermal Inertia • Thermal Inertia (TI) = measures the amount of energy it takes to heat up a materials and how long it takes that material to cool down after the energy source is removed • High TI = requires more energy to heat up and cool down • Low TI = requires less energy to heat up and cool down
Thermal Inertia • Think of a sandy beach during the day: As you walk around, what is really hot? • Think of that same sandy beach at night: What is the temperature like of the sand? How about the rocks? What takes more energy to be heated up and cool down (loose it’s heat)? = High TI What takes less energy to heat up and cool down (heats up and cools down more quickly)? = Low TI
Thermal Inertia • TI is related to grain size • Rocks • Sand • “Dust”/finer grained materials
Heating Effects Heating Effect Visible Day IR Night IR Sunlight High Bright Hot N/E Low Dark Cold N/E Albedo High Bright Cold N/E Low Dark Hot N/E TI High Low
Heating Effects Heating Effect Visible Day IR Night IR Sunlight High Bright Hot N/A Low Dark Cold N/A Albedo High Bright Cold N/A Low Dark Hot N/A TI High N/A N/A Hot Low N/A N/A Cold