Department of Climate and Space Sciences and Engineering in the College of Engineering at the University of Michigan

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Electric Activity on Mars Reignites Challenging Discussion

Posted: June 8, 2009

Electric Activity on Mars Reignites Challenging Discussion Download File(s): Mars_activity0609.pdf

Thirty years ago, with soil measurements from the Viking landers, the possibility that martian dust storms might be electrically active like Earth’s thunderstorms and thus, might be a source of reactive chemistry, was discussed and considered among planetary scientists. But the hypothesis was untestable. In 2006, using theoretical modeling, laboratory experiments and field studies on Earth, a group of planetary scientists suggested that, while oxidizing chemicals could be produced by martian dust storms, there was no direct evidence that lightning occurred during these events.

However, a new study, the results of which will be published in an upcoming issue of the AGU journal Geophysical Research Letters, by University of Michigan faculty members Chris Ruf and Nilton Renno, along with recently graduated student Jasper Kok, Etienne Bandelier, lead research engineer Steve Gross, and their two JPL collaborators, may have turned the thinking back thirty years. The study found direct evidence that “non-thermal microwave radiation” was emitted by powerful electric discharges in a martian dust storm.

“What we saw on Mars was a series of huge and sudden electrical discharges caused by a large dust storm,” said Chris Ruf. “On Earth this is sometimes called “dry lightning” because there is no rain associated with it. Clearly, there was no rain associated with the electrical discharges on Mars. However, the implied possibilities are exciting.”

The findings are based on observations made using an innovative microwave detector developed at the U-M Space Physics Research Laboratory. The kurtosis detector, which is capable of differentiating between thermal and non-thermal radiation, took measurements of microwave emissions from Mars for approximately 5 hours/day for 12 days between May 22 and June 16, 2006. In the data collected on June 8, both an unusual pattern of non-thermal radiation and an intense Martian dust storm occurred, the only time that non-thermal radiation was detected.

The data was reviewed as to the strength, duration and frequency of the non-thermal activity as well as the possibility of other sources. But each test led to the conclusion that the dust storm was probably the cause of the “dry lightning.”

“Electric activity in martian dust storms has important implications for Mars science,” said Nilton Renno. “It affects atmospheric chemistry, habitability and preparations for human exploration. It might even have implications for the origin of life, as suggested by the Miller/Urey experiments in the 1950s.”

Related links:  “The Emission of Non-Thermal Microwave Radiation by a Martian Dust Storm” (PDF File)
    Christopher Ruf
    Nilton Renno
    Space Physics Research Laboratory (SPRL)

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