Was there really no life there? You might think that the driest place on Earth is the Sahara. Surprisingly, the driest deserts are cold, not hot. While the Viking equipment missed any signs of life in the Atacama, new understanding of extremophiles—life found in extreme conditions—led NASA scientists to look beneath the soil and within rocks, where they found photosynthetic bacteria.
And if life can exist here, in the most inhospitable place on Earth, we might also find it on the next mission to Mars. Today, NASA is using these two deserts to develop equipment and tests for organics that will be more sensitive in future Mars missions.
The World's Largest Deserts Geology. Discover the natural wonders of Earth on over radio stations nationwide. Download PDF zip file. And by extension, no life on Mars? If possible, space explorers test their hypotheses and equipment on Earth before trying them out in space. Apollo astronauts learned about geology and practiced driving moon rovers in the deserts of the southwestern United States.
They are almost pure halite, a form of sodium chloride, and when the humidity is above 70 per cent small pores in the rock fill with a liquid salt solution which the hardy bacteria can exploit. The mineral also lets enough sunlight through for the bacteria to carry out photosynthesis, while protecting them from destructive ultraviolet radiation — just as some other desert cyanobacteria survive inside translucent quartz.
McKay thinks that the Atacama bacteria must photosynthesise during a brief interval in the morning, after the rocks have collected water from the relatively moist night air. McKay suggests that this way of harnessing minute amounts of moisture might also have allowed microbial life to survive in the arid conditions on Mars. Halite and similar rocks have been found on Mars by the rover Opportunity. They might still be clinging on in niches somewhere on the planet, but they would have to cope with even drier conditions than the Atacama, more intense ultraviolet radiation, lower temperatures and, worst of all, a near vacuum.
Wierzchos returned to the Atacama last week to collect more samples in the hope of understanding these organisms better, and to see whether their remains might be detected long after they have died off. The main crops grown are peaches, dates and apricots. Nearby, the desert is low-lying and covered by sand dunes up to feet m in height. Arica is the driest city on the planet, though not quite the driest place.
It's a port city, and despite the lack of wet stuff from the sky, Arica does have a high level of humidity and cloud cover. While the air is wet, the moisture doesn't quite make it to the ground. The surrounding Atacama Desert is in a rain shadow that squeezes moisture out over the mountains and carries only dry air to the desert some places in the desert have not received rain in more than years!
Though Antarctica summons a mental picture of snow-covered terrain, it's Dry Valleys are actually the world's driest spot. The valleys have extremely low humidity and almost no ice or snow cover the largest ice-free region on the continent. Nearby mountains are high enough that they block seaward flowing ice from reaching the valleys. The unique conditions are caused, in part, by powerful katabatic winds these occur when cold, dense air is pulled downhill by the force of gravity.
The winds can reach speeds of mph kph , heating as they descend, and evaporating all water, ice and snow. The valleys are considered the closest of any of Earth's environments to the planet Mars , and scientists are studying the ecosystem to better understand the surface of the Red Planet. Live Science.
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