New unmanned moon mission may unlock planets mysteriesDecember 17th, 2007 - 4:25 pm ICT by admin
Washington, Dec 17 (ANI): New images taken from NASAs orbiting HiRise camera have revealed surprising details about two bizarre features that are in the form of spiders and fans, on the surface of Mars.
These formations appear during the spring in a region near the planet’s south pole, which is dense with unusual features.
For example, fan shaped layers of dust, which are in fact gas jets; accumulate on top of the region’s polar ice, spreading in the direction of the prevailing winds.
According to scientists, the polar ice is made up of carbon dioxide, which is warmed by spring sunshine, causing it to transform directly into gas and spew out dust like a dirty geyser.
The warm dirt transfers heat to the bottom layer of ice, which turns to gas. As pressure builds, the gas scours channels beneath the ice, picking up dust. When the moving gas finds a hole or breaks through a weak spot, the dust spews into the air and then rains back to the surface downwind.
The new HiRise images clearly show the network of pipelike channels feeding each jet. Some are simply lacelike patterns, but others have legs extending in all directions.
“You can see the sort of spiderlike shape,” said Candice Hansen of NASA’s Jet Propulsion Laboratory. “They drape over the local topography. In fact, they love to sit on top of little hummocks,” she added.
HiRise was also able to determine the composition of bright streaks that often angle outward from the dust deposits, like slightly wider fans.
These streaks are comprised of carbon dioxide rather than dust, said Tim Titus of the U.S. Geological Survey in Flagstaff, Arizona. The fact that the white streaks and the black fans don’t perfectly align indicates that they were produced at different times of the day, he added.
According to Titus, at dawn, there isn’t enough heat from the sun to melt any gas. Later gas flows form, but they’re not fast enough to pick up any dust. When this gas escapes into the air, it expands and cools rapidly, raining back carbon dioxide “snow” to the surface.
“Our calculation is that as much as 2 percent of the gas can get converted back into frost,” Titus told National Geographic News. “That’s plenty to form these white fans,” he added.
According to scientists, the pictures also provide insights into wind patterns and daily cycles on the red planet.
“Like the Earth, Mars experiences seasons. Unlike the Earth, the polar cap is made out of carbon dioxide, or dry ice,” said Hansen. “The carbon dioxide ice is translucent. That allows sunlight to penetrate and warm the surface below,” she added. (ANI)
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