Mars orbiters studying global dust storm

Scientists hope to learn why some annual local dust storms become global events.

NASA’s Mars orbiters have been taking advantage of the rare dust storm that has engulfed the Red Planet for weeks to study its  effects on the Martian atmosphere and surface.

Dust storms that envelop the entire planet occur approximately once every three to four Martian years, or every six to eight Earth years.

In this case, a small, localized dust storm that formed on May 30 began a series of runaway storms that by June 20 created a dust cloud surrounding the entire planet.

On the ground, NASA’s Opportunity rover, which requires sunlight to recharge its batteries, went dormant and stopped communicating with Earth. However, the dust covering the rover acts as insulation, preventing its temperatures from dropping too low.

NASA’s Curiosity rover, which is nuclear-powered, can operate without sunlight and is studying the storm from its surface vantage point.

The majority of data on the storm is being collected by NASA’s Mars Reconnaissance Orbiter (MRO), Mars Odyssey, and Mars Atmosphere and Volatile EvolutioN (MAVEN).

Two MRO science instruments, the Mars Color Imager (MARCI) and the Mars Climate Sounder (MCS) are actively studying the storm. MARCI is tracing the storm’s evolution by mapping the planet during Martian afternoons while MCS is measuring changes in atmospheric temperatures at various altitudes.

When dust in the Martian atmosphere is heated by the Sun, wind patterns across the planet and even circulation of the entire atmosphere are altered. These temperature changes affect the storm by altering wind directions and carrying more surface dust into the atmosphere.

“The very fact that you can start with something that’s a local storm, no bigger than a small [U.S.] state, and then trigger something that raises more dust and produces a haze that covers almost the entire planet is remarkable,” said MRO project scientist Rich Zurek of NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California.

Through its Thermal Emission Imaging System (THEMIS), Mars Odyssey is tracking Mars’s surface and atmospheric temperatures and measuring atmospheric dust levels, all of which help scientists learn how such storms grow, evolve, and dissipate.

“This is one of the largest weather events we’ve seen on Mars. Having another example of a dust storm really helps us to understand what’s going on,” emphasized Michael Smith of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, who works on THEMIS.

MRO has increased its atmospheric observations from every 10 days to twice a week since the storm began.

Instead of studying the storm, MAVEN is focusing on how it impacts Mars’s upper atmosphere approximately 62 miles (100 km) above the surface. This orbiter’s primary goal is to determine the fate of ancient Mars’s atmosphere, and its findings suggest that atmosphere was stripped by the solar wind between 3.5 and four billion years ago.

MAVEN scientists hope to learn whether atmospheric escape is altered when dust traps heat from the Sun. A warmer atmosphere may have caused ancient water vapor to rise to a position where it was broken up by sunlight, causing its hydrogen atoms to escape into space.


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