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article imageMassive dust storm on Mars has become a 'global weather event'

By Karen Graham     Jun 21, 2018 in Science
A massive dust storm on Mars that covered one-fourth of the planet just a week ago has grown into a global weather event, NASA officials said on Wednesday.
In Perseverance Valley, the weather has been atrocious of late, so much so that NASA’s Opportunity rover has gone offline because it is dependent on solar power, and well, there is no sunlight.
This situation has NASA scientists a bit worried because the bot is unable to recharge its batteries - and as its power supply continues to dwindle - there is the fear it might "freeze out" because there won't be enough power to feed the inbuilt heater, according to ZME Science.
About 5,000 miles away, on the opposite sides of Mars, NASA's Curiosity rover, which is nuclear powered, is busy snapping photos, even as the weather grew worse.
"As of Tuesday morning, June 19, the Martian dust storm had grown in size and was officially a "planet-encircling" (or "global") dust event, according to Bruce Cantor of Malin Space Science Systems, San Diego, who is deputy principal investigator of the Mars Color Imager camera onboard NASA's Mars Reconnaissance Orbiter.
This graphic compares atmospheric opacity in different Mars years from the point of view of NASA’s...
This graphic compares atmospheric opacity in different Mars years from the point of view of NASA’s Opportunity rover.
NASA
NASA is reporting the dust from the "planet-encircling" storm is rapidly settling on Curiosity, having more than doubled over the past weekend. The storm's light-blocking factor, called "Tau" has grown to over 8.0 above at the Gale Crater where Curiosity is right now. Tau in astronomy is a measure of optical depth, or how much sunlight cannot penetrate the atmosphere.
Opportunity is experiencing 11 Tau, a high enough value to make any accurate measurements from its instruments impossible. But even Curiosity cameras are having a few problems, mainly because with the dust being so thick, it takes longer for exposure times. NASA is tilting the cameras toward the ground after each exposure to limit the amount of dust in the lenses.
Mars has a history of dust storms
NASA says the dust storm encircling Mars is comparable in scale to a similar storm observed by Viking I in 1977, but not as big as the 2007 storm that Opportunity previously weathered.
These two views from NASA’s Curiosity rover  acquired specifically to measure the amount of dust i...
These two views from NASA’s Curiosity rover, acquired specifically to measure the amount of dust inside Gale Crater, show that dust has increased over three days from a major Martian dust storm. The left-hand image shows a view of the east-northeast rim of Gale Crater on June 7, 2018 (Sol 2074); the right-hand image shows a view of the same feature on June 10, 2018 (Sol 2077). The images were taken by the rover’s Mastcam.
NASA/JPL-Caltech/MSSS
This storm is also different from the massive storms observed by Mariner 9 (1971-1972) and Mars Global Surveyor (2001). Those dust storms totally obscured the planet, except for the peaks of Mars' tallest volcanoes. There is no telling when the present storm will clear up or if it will get even worse.
On Earth, these types of storms don't occur because of our thick atmosphere, stronger gravity, and thick vegetation. NASA explains why it is vastly different on Mars: "Martian dust storms are common, especially during southern hemisphere spring and summer, when the planet is closest to the Sun. As the atmosphere warms, winds generated by larger contrasts in surface temperature at different locations mobilize dust particles the size of individual talcum powder grains. Carbon dioxide frozen on the winter polar cap evaporates, thickening the atmosphere and increasing the surface pressure. This enhances the process by helping suspend the dust particles in the air. In some cases, the dust clouds reach up to 40 miles (60 kilometers) or more in elevation."
While some of these Martian storms will only last a few weeks, others can go on for years. This is why having the two rovers and the information they can send back is so important to scientists.
You can get updates about the dust storm, and Opportunity’s status, at NASA’s Mars Storm Watch page.
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