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THEMIS image of Earth
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THEMIS image of Earth

October 7, 2009
The 2001 Mars Odyssey's thermal emission imaging system acquired these images of the Earth using its visible and infrared cameras as the spacecraft left the Earth. The visible light image shows the thin crescent viewed from Odyssey's perspective. The infrared image was acquired at exactly the same time, but shows the entire Earth using the infrared's "night-vision" capability. In visible light, the instrument sees only reflected sunlight and therefore sees nothing on the night side of the planet. In infrared light the camera observes the light emitted by all regions of the Earth. The coldest ground temperatures seen correspond to the nighttime regions of Antarctica; the warmest temperatures occur in Australia. The low temperature in Antarctica is minus 50 degrees Celsius (minus 58 degrees Fahrenheit); the high temperature at night in Australia 9 degrees Celsius (48.2 degrees Fahrenheit). These temperatures agree remarkably well with observed temperatures of minus 63 degrees Celsius at Vostok Station in Antarctica, and 10 degrees Celsius in Australia. The images were taken at a distance of 3,563,735 kilometers (more than 2 million miles) on April 19, 2001 as the Odyssey spacecraft left Earth.

Mars Odyssey carries three scientific instruments designed to tell us what the Martian surface is made of and about its radiation environment: a thermal-emission imaging system, a gamma ray spectrometer and a Martian radiation environment experiment. Odyssey will arrive at Mars on October 24, when it will fire its main engine and be captured into Mars' orbit.

The Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. Principal investigators at Arizona State University in Tempe, the University of Arizona in Tuscon, and NASA's Johnson Space Center, Houston, Texas, will operate the science instruments. Lockheed Martin Astronautics, Denver, Colo., is the prime contractor for the project, and developed and built the orbiter. Mission operations will be conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena. The thermal emission imaging system was built by Raytheon Santa Barbara Remote Sensing, Santa Barbara, Calif. and is operated by Arizona State University.