Last updated on April 24, 2014 at 1:21 EDT
THEMIS image of Earthmoon
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THEMIS image of Earth/moon

October 7, 2009
2001 Mars Odyssey's thermal emission imaging system took this portrait of the Earth and its companion Moon, using the infrared camera, one of two cameras in the instrument. It was taken at distance of 3,563,735 kilometers (more than 2 million miles) on April 19, 2001 as the 2001 Mars Odyssey spacecraft left the Earth. From this distance and perspective the camera was able to acquire an image that directly shows the true distance from the Earth to the Moon. The Earth's diameter is about 12,750 kilometers, and the distance from the Earth to the Moon is about 385,000 kilometers, corresponding to 30 Earth diameters. The dark region seen on Earth in the infrared temperature image is the cold south pole, with a temperature of minus 50 degrees Celsius (minus 58 degrees Fahrenheit). The small bright region above it is warm Australia. This image was acquired using the 9.1 micron infrared filter, one of nine filters that the instrument will use to map the mineral composition and temperature of the Martian surface. From this great distance, each picture element (pixel) in the image corresponds to a region 900 by 900 kilometers (about 560 by 560 miles). Once Odyssey reaches Mars orbit each infrared pixel will cover a region only 100 by 100 meters on the surface (about 330 by 330 feet), about the size of a major league baseball field.

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.