‘Perfect Storm’ Encircles Mars
A massive wind-driven dust storm, dubbed “the perfect storm” by scientists, is raging across the surface of Mars, shrouding nearly all of the Red Planet in a veil of orange dust.
“This is a planetary-scale event, one that if it were here on Earth would have truly unimaginable consequences,” said James Garvin, the head of NASA’s Mars exploration program.
Such planet-encircling dust storms are thought to occur periodically on Mars, but this is the first time scientists have been able to watch as one of the massive storms blossomed.
The powerful Hubble Space Telescope and various cameras aboard the orbiting Mars Global Surveyor have been snapping pictures since the storm began at the end of June. The photos were released Thursday.
“This is an unprecedented view, having a daily snapshot from Mars,” said Michael Malin, a planetary scientist who runs the Mars Orbiter Camera, which took many of the photos.
In three months, the storm has carried dust around the entire planet, leaving only the polar regions unobscured. The dust has traveled 43 miles into the Martian atmosphere, powered by relentless 70-mph winds peppered by much stronger gusts.
“Imagine a hurricane parked off Florida for 90 days,” Malin said. “This storm was blowing for 90 days.”
Planet’s Storms Were First Noted in 1796
The dust has made Mars look blurry. All of the planet’s features, except for its bright carbon dioxide ice caps and its tallest volcanoes, are obscured. The dust also has darkened the planet’s surface and has cooled it by 10 degrees Fahrenheit. The only equivalent events to occur on Earth are from massive volcanic explosions, such as Mt. Pinatubo, which fill the atmosphere with dust and lower global temperatures--although by considerably lesser degrees.
Dust storms have been a visible feature of Mars for centuries. They were first described as “yellow clouds” in 1796. In 1956, scientists observed what they thought was a planet-encircling dust storm, but such storms were not documented fully until 1971. That year, Mariner 9, the first spacecraft to orbit Mars, found the largest known storm to date--extending to the poles and sending dust 50 miles into the atmosphere.
Dust storms and dust devils can occur on Mars in any season, but the global storms are most likely to occur when it is spring and summer in the planet’s southern hemisphere, said Richard W. Zurek, an expert on the Martian atmosphere at JPL. In these months, Mars is closest to the sun and there is more heating, which can amplify winds.
Scientists do not know why some dust storms remain small and localized while others bloom into planetary events. Nor do they know why storms develop in some years but not others. The new images suggest that localized storms somehow trigger the bigger events.
“This was not just one dust storm,” said Philip R. Christensen, a planetary geologist at Arizona State University who analyzed the heat generated by the storm with an infrared instrument he has aboard the Mars Global Surveyor. “They explode out. . . . The storms actually spawn other storms.”
Once they started to expand, the storms raced across the planet’s equator. Some of the dust moved 2,500 miles in two days, Malin said.
Because there was no global dust storm during the last Martian summer, scientists can compare images taken then with the new pictures to “see the onset of these storms and try to understand” why they formed, Zurek said.
Storms Could Hinder Exploration of Planet
The newest Mars spacecraft, Odyssey, is expected to enter the Martian atmosphere Oct. 23. Though the dust storm is dying down and not expected to cause a problem for the spacecraft, engineers are relying on the constant weather monitoring in case another dust storm arises in coming months. “We won’t be caught unaware,” said Zurek, who is assisting the navigation team.
The other group interested in the new Martian weather reports are planning teams from NASA who are looking for ways for humans to safely explore Mars. The dust, which is much finer than dust on Earth, could foul respiration and power systems. Because it clings to everything, it also could prove to be a huge nuisance.
Said the space agency’s Garvin: “Dust matters.”
