Water Ice: Not Just for Earthlings Any More

Without water, life as we know it could not have evolved on Earth.

Or Mars.

As it turns out, there's water on both planets.

According to Science Daily, "NASA's Viking Lander 2, digging into mid-latitude Mars in 1976, might have struck ice if it had dug 10 centimeters (4 inches) deeper."

In fact, it seems that every time a meteorite strikes the surface of Mars, a layer of water ice forms on the surface. This discovery came about when scientists, checking out images sent by NASA's Mars Reconnaissance Orbiter, noticed bright spots in previously dark areas. Investigating with a spectrometer, it quickly became clear that the bright spots were caused by the sun reflecting off thin sheets of water ice.

Over just a few weeks, the water ice disappears, vaporizing in the thin Martian atmosphere. But there's no doubt that the water is real -- and, according to researcher Shane Byrne of the University of Arizona, "This ice is a relic of a more humid climate from perhaps just several thousand years ago."

What, precisely, does this discovery mean to the search for extraterrestrial life? So far, no evidence has suggested the presence of little green men. But water ice is one step closer to that inevitable moment.

Photo courtesy of NASA