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Washington: A storm of tiny dust particles has engulfed much of Mars in the past two weeks.
The weather conditions prompted NASA's rover Opportunity to suspend its scientific operations.
But across the globe, NASA's Curiosity rover, which has studied Martian soil at Gale Crater, is expected to remain largely unscathed by dust.
While Opportunity is powered by sunlight, which is erased by dust at its current location, Curiosity has a nuclear power battery that runs day and night.
The Martian dust storm has gained momentum and is now officially a "global" (or "global") dust event.
Although Curiosity is on the other side of Opportunity's March, dust has steadily risen over this weekend. The atmospheric mist blocking sunlight, called "tau", is now above 8.0 at Gale Crater – the highest tau ever recorded by the mission.
Tau was last measured close to 11 on Opportunity, thick enough so that accurate measurements are no longer possible for the oldest active rover in Mars.
For NASA scientists watching from the ground, Curiosity offers an unprecedented window to answer a few questions. One of the biggest: Why some Martian dust storms last for months and grow massively, while others stay small and last only a week.
"We have no good idea," said Scott D. Guzewich, an atmospheric scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland, leading the investigation into the Curiosity dust storm.
Curiosity, he pointed out, plus a fleet of spacecraft in the orbit of Mars will allow scientists for the first time to gather a mine of information on dust from both the surface and of space. The last global-magnitude storm that enveloped Mars took place in 2007, five years before Curiosity landed there.
In the animation, Curiosity was facing the edge of the crater, about 30 kilometers from where it is located inside the crater. The daily photos captured by his Mast Camera, or Mastcam, showed that the sky was becoming foggy. This wall of fog obstructing the sun was about six to eight times thicker than normal for this period of the season.
Curiosity engineers at NASA's Jet Propulsion Laboratory in Pasadena, California, have studied the potential of the growing dust storm to affect rover instruments, and say it poses little risk.
The most important impact is on the rover cameras, which require additional exposure time due to low illumination. The mobile is already systematically pointing his Mastcam to the ground after each use to reduce the amount of dust blowing on his optics.
Martian dust storms are common, especially in the spring and summer of the southern hemisphere, when the planet is closest to the Sun. As the atmosphere heats up, winds generated by greater surface temperature contrasts at different locations mobilize dust particles the size of individual talcum powder grains.
Frozen carbon dioxide on the winter fleece hood evaporates, thickening the atmosphere and increasing surface pressure. This enhances the process by helping to suspend dust particles in the air. In some cases, dust clouds reach up to 40 miles (60 kilometers) or more in altitude.
Although common, Martian dust storms usually remain in a local area. In contrast, the current storm, if it occurred on Earth, would cover the combined North American and Russian zone, Guzewich said.
The dust storm may seem exotic to some Earthmen, but it's not unique to Mars. The Earth also has dust storms in desert regions like North Africa, the Middle East and the Southwest United States.
But the conditions here prevent them from spreading globally, said Ralph A. Kahn, a senior researcher at Goddard who studies the atmospheres of the Earth and Mars.
These include the structure of our thicker atmosphere and the stronger gravity that helps to build up the dust. The earth also has a vegetal cover on the ground that binds the soil with its roots and helps to block the wind and rain that wash the particles out of the atmosphere.
The discoveries are made by NASA and Goddard Space Flight Research Center. (ANI)
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