PASADENA, Calif. (AP) - NASA is tracking a regional dust storm on Mars, but says it has not affected the operations of its two rovers on the surface.

The space agency said Wednesday the storm raging in the Martian southern hemisphere was spotted earlier this month by the Mars Reconnaissance Orbiter circling overhead.

The storm came within 840 miles of Opportunity's location. On the opposite side of the red planet, a weather station aboard NASA's newest rover, Curiosity, detected changes in air pressure and overnight temperature related to the storm.

Scientists want to learn more about Martian dust storms, including why some morph into storms that blanket the planet.

If this latest storm turns into a global one, the solar-powered Opportunity would see an energy decline. Curiosity, powered by plutonium, won't be as directly affected.

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