Telescopes spot big dust storm on Mars

The view from Mars
NASA's Mars rover Opportunity, currently exploring the Meridiani Planum, has seen some signs of the dust storm, which is apparently nearby.

"This may be the second-biggest dust storm that Opportunity has seen," Mark Lemmon, a rover science team member from Texas A&M University, told Space.com.

He said he saw the images taken by Sherrod, "and I waited very impatiently for the rover's downlink to come in."

Lemmon said that the data returned to Earth Friday by Opportunity showed elevated dust levels at Meridiani Planum, which were measured at an optical depth of about 1.4. The largest dust storm experienced by the rover occurred in June and rated an optical depth of about 2, he added.

In comparison, a smoggy day in Los Angeles would rate an optical depth of about 1.0, and moderate days on Mars are about 0.5, NASA officials said.

Martian dust storms blot out sunlight from rover panels, but otherwise are relatively harmless to the robotic explorers, Lemmon said.

While dust storm activity in Opportunity's region of Mars is winding down, team members with NASA's Mars Global Surveyor orbiter noticed a rise in activity about two weeks ago, Lemmon said. Researchers are not sure how large the current storm could grow.

"We started seeing more and more dusting on the solar panels," he added. "And we have indirect evidence that these storms are windy. We've seen material blown out of the rover tracks over the last two weeks."

Tickled by the fingers
Lemmon suspects that Opportunity experienced one of the "fingers" of the storm photographed by Sherrod, adding that later atmospheric measurements were lower than the 1.4 optical depth seen earlier, but not quite at the moderate 0.5.

"Because we got the warning that something was happening ... we were able to get in some atmospheric observations in," Lemmon said. "So if this does give us a direct hit over the rover, we're ready."

Lemmon said he and other researchers are eager to learn the properties of the dust within the storm and compare it to the material Opportunity sees daily.

Meanwhile, Opportunity's robotic twin Spirit has found some signs of additional atmospheric dust at its Gusev Crater landing site on the other side of Mars.

Lemmon said Spirit detected an optical depth of about 0.6, still well within the moderate range, but would likely not experience as significant an increase in dust levels as Opportunity.

Space.com's Tariq Malik contributed to this report.

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