THE FRIENDLY GHOST
Dust storm imaged by the Mars Orbiter Camera in a region just northwest of Elysium Mon June 8, 2006. Shadows on the northeast side of storm indicate that the dust cloud reaches at least 22 miles (35 km) above the surface. The white arrow indicates the location of the storm. Credit: Ruf, et al., GRL
The first detection of lightning in a Martian dust storm has likely been made by a new detector on a radio telescope.
Scientists have long thought that as with dust devils and storms here on Earth, Martian dust storms should produce lightning. But direct evidence of electric discharges on the red planet was lacking.
That's where an innovative detector installed in a 34-meter radio telescope in the Deep Space Network lent a hand.
This detector captured the signature of the radiation given off by the lightning for a few hours during a Martian dust storm on June 8, 2006.
"We saw the lightning," said Christopher Ruf of the University of Michigan in Ann Arbor, who first developed the new detector for use on Earth-orbiting weather satellites.
While lightning was expected to occur on Mars, "it was a surprise that the signal was so strong," Ruf told SPACE.com.
The lightning wouldn't look quite like what we see on Earth during a thunderstorm — "It wouldn't likely be the big lightning bolts," Ruf said, instead it would look more like a glow in the clouds, akin to so-called heat lightning here on Earth.
The dust storm the lightning was detected in was a major one, measuring 22 miles (35 kilometers) deep, but "it should be there in smaller storms" too, Ruf said.
"These dust storms happen all the time there," he added.
The lightning isn't a major worry for the rovers currently on the Martian surface (or any future robotic or human explorers), because to cause a problem, the discharge would have to occur in the cloud right at the location of the rover.
But the lightning could cause chemical reaction that affect the chemistry of the Martian atmosphere and surface, creating caustic compounds that would affect human equipment and would have to be factored into designs, Ruf explained.
Another intriguing consideration is how lightning might affect the possibility of past or present life on Mars. Life is more likely to occur with lightning than without, Ruf said, because electric currents make for more complex molecules, but Ruf isn't holding his breath.
Scientists are working to install more sensitive detectors on telescopes to see if they can make more measurements of Martian lightning in the future.