MGS MOC Release No. MOC2-171, 10 August 1999
The first two pictures (A and B, above) show a color composite view of the Amazonis dust devils as they appeared to the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) red and blue wide angle cameras; the white arrows in MOC2-171b (B, above) point to each individual dust devil. The third picture (C, above) is a GIF "movie" (Click on the Icon) that shows dust devil occurrences on two different dates in May 1999. The scene in this "movie" is about 88 kilometers (55 miles) across. The fourth picture (D, above) is a diagram that compares the typical heights of dust devils and tornados on Earth with dust devils on Mars. Click on the "cartoon" icon to see the entire diagram, including a comparison with the heights of the tallest mountains on Earth (Himalayas) and Mars (Olympus Mons).
The heights of dust devils in MOC images can be estimated from the length of the dark shadows that they cast. The shadows in these pictures all point toward the northeast (toward upper right). The largest dust devil in these pictures towers nearly 8 kilometers (5 miles) above the martian surface, and has a lower basal plume of dust that suggests substantial surface flow of wind and dust into the rising column.
In the MOC images shown here, north is up, and the sun's illumination is from the lower left. The 40 kilometer scale bar also indicates a distance of about 25 miles. Additional MOC images regarding these and other dust devils:
Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.
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