Greensboring :: Outside The Media. Beyond The News.

An image sent back from the Red Planet has revealed an object bearing an uncanny resemblance to a wooden log. It was captured by the Mars Rover near the Endurance Crater.

The find has excited conspiracy theorists on blogs and websites who claim it is evidence there are vast forests on Mars that have been kept from the public.

It is more likely to be a case of pareidolia - where a random stimulus is perceived as having significance, be it a symbol seen in a cloud or a face on a piece of toast. VIA

"The key to figuring out the spiders and the spots," says Christensen, "was thinking through a physical model for what was happening." The whole process, he explains, begins during Mars' frigid Antarctic winter, when temperatures drop to -200° F. That's so cold that the Martian air - 95 percent carbon dioxide - freezes out directly onto the surface of the permanent polar cap, which is made of water ice covered with layers of dust and sand.

This seasonal deposit begins as a layer of dusty CO2 frost. Over the winter, the frost recrystalizes and becomes denser, a process called annealing. The dust and sand particles caught in the frost slowly sink. By spring, with the Sun about to rise, the frost layer has become a slab of semi-transparent ice about 3 feet thick, lying on a substrate of dark sand and dust.

Sunlight passing through the slab reaches the dark material and warms it enough that the ice touching the ground sublimates - it turns directly into gas. As days pass and the Sun rises higher, sublimation continues. Before long, the warmed substrate generates a reservoir of pressurized gas under the slab, lifting it off the ground.

Soon after, weak spots in the slab break through, forming narrow vents, and high-pressure gas roars out at speeds of 100 miles per hour or more. Under the slab, the gas erodes the ground as it rushes toward the vents, snatching up loose particles of sand and carving networks of grooves that converge on the vents.

"Once a spider becomes established," says Christensen, "it affects the surface so that a vent will form in the same place the following year."

As they erupt, the jets carry loose sand and particles high in the air. The largest and heaviest particles fall closest to the vent, piling up around it to make the spots. As lighter sand grains tossed out by the jet blow downwind, they create the fans, which can extend tens to hundreds of yards. The lightest particles, meanwhile, drift away on the wind to form a thin layer of dust.