Electric Devils Could Harass Mars Explorers
(From the July/August 2004 issue of StarDate magazine)
While the Spirit and Opportunity rovers continue to roll across the Martian
landscape, researchers have found evidence that other mobile residents of
the desert planet could prove a nuisance to future manned missions.
A team led by Peter Smith of the University of Arizona found that the
twisting columns of air known as dust devils produce unexpectedly large
electric fields, which could create a host of problems for human explorers.
Dust devils are common in desert environments on Earth. They form as
different parts of the desert floor heat at different rates, creating rising
currents of warm air. Changes in wind speeds and directions above the ground
cause them to spin like small, weak tornadoes.
Since Mars is a big desert, plenty of dust devils crawl across its surface.
But in the planet’s thin atmosphere and light gravity, they grow much larger
than on Earth — up to several hundred yards across and several miles high.
To understand how dust devils might affect future missions to Mars,
scientists tracked the little twisters across Nevada and Arizona. They found
that dust devils create electric fields. The fields form because smaller
particles of dust, which climb higher into the sky, develop a negative
electrical charge, while larger, lower particles have a positive charge.
This acts like two poles of a battery, setting up an electrical field.
Since the dust devils on Mars can grow much bigger than those on Earth,
their fields could be much stronger. Smith’s team suggests that large dust
devils could cause electronic components to arc or short out, make the fine
Martian dust stick to space suits and power-producing solar panels,
interfere with radio transmissions, and cause other potential problems. -- Damond Benningfield
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