Rough Notes:
| Credit: NASA/JPL/Malin Space Science Systems
Image credit: NASA/JPL/Texas A&M Gusev crater dust devil |
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pic of the day Links: Society for
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Sep 16, 2005 In Mars’ thin and dry atmosphere, dust devils are the equivalent of Earthly lightning. And they, too, leave behind a record of their passing burned into the soil. Because Mars is a charged body orbiting within a cell of plasma that surrounds the Sun (a stellar plasma sheath), an electric current flows to the Martian surface. Mars’ atmosphere, like Earth’s, acts as a self-repairing capacitor, insulating the surface until breakdown voltage is reached. Then the current flows through the atmosphere to the surface, persisting until the electric field strength becomes too weak to sustain the discharge. In Mars’ thin and dry atmosphere, these arcs take the form of giant vortexes—miles-high dust devils. The electric currents powering these electric tornados burn the surface as they pass over it, leaving the characteristic trail of scorched soil. The Mars Orbiter Camera captured this bird’s eye view of a dust devil burning its way across the landscape and leaving behind a blackened path. (The shadow of the dust devil lies to the right of it.) Many other dark trails in the vicinity attest to the frequency of dust devils in this area. |
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Copyright 2005: thunderbolts.info |
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