One of the driest places on Earth is Atacama Desert but the driest place in this desert is found near Yungay - abandoned mining town.
This is highly unusual place which has attracted attention of astrobiologists due to high similarity to Mars environment. Only lately, after intense search here have been found some microorganisms in some places.
Realm of nitrates
Atmosphere per 78% consists of nitrogene. Photochemical reactions in the upper layers of atmosphere create nitrates which are deposited everywhere on Earth. But almost everywhere these nitrates immediately are consumed by microorganisms. Only in a few places of the world there is too little water and - as a result - too little life for denitrification. Such places are found in Dry Valleys of Antarctica, Nevada and California (United States) and in northern Kenya. But the richest nitrate deposits are found in Atacama Desert.
The driest place in Atacama desert is the area around Yungay town because it has so called "double rain shadow": a lower range screening it from the Pacific and the much higher Andes stopping any rain coming from the rainforests of Paraná and Amazon.
Rain comes here approximately once per 10 years and precipitation is measured in millimeters per decades. There has been fixed also a period without rain lasting for 40 years.
Nowhere else in the world there are found that many nitrates as here. Throughout 10 - 15 million years the nitrate has virtually covered this land. Nitrates form up to 28% of the soil, forming a specific rock called caliche. Layer of caliche in some places is even 5 m thick.
Besides nitrates here are found other water soluble salts, which often are not found elsewhere in the world - such as perchlorates and iodides. Most salts came here by wind from the ocean and from local evaporated lakes whose sediments also are moved around by the wind.
Wealth from the desert
Nitrogen is one of the primary plant nutrients and nitrate fertilizers can do wonders in agriculture. This was discovered in the middle of 19th century and agricultural business immediately started to look for this excellent possibility to boost their profit.
Soil with weight content of nitrates above 7% was considered to excellent fertiliser - a kind of "fertiliser ore". In short time Atacama desert gained huge popularity as the main producer of nitrate fertilizer in the world. Chile managed to gain the control over most of deposits and for decades this was the main source of income in Chile.
In late 19th century in the lifeless hills developed a miner town Yungay and other mining towns.
In 1920ies there was developed industrial method for artificial synthesis of nitrate fertilizers and in 1940ies the large scale mining of fertilisers in Atacama desert ended. Since then the town has been almost completely abandoned. This was heavy blow to the economics of Chile as well, ruining its financial system and proving how unsafe might be the dependance of state economy on natural resources.
Astrobiologists look for life
As fertiliser business left Atacama, here came completely different people - astrobiologists.
Their main interest is to find a border in the ground between areas without life and with life. When such border is found, there could be researched which factors decide whether life exists or not. These findings could be of great assistance in the quest for life in outer space.
It is surprisingly hard to find a soil on Earth without life. Microbial activity is found everywhere from the deepest seas to the highest mountains, from the coldest land to hottest springs. It seems that only complete lack of water leads to complete lack of life. Microorganisms are found even in the Dry Valleys of Antarctica which are nearly as dry and a lot colder than Atacama Desert.
Near the abandoned buildings of Yungay is located University of Antofagasta Desert Research Station. From time to time in this small house come interested scientists from all over the world. With different methods they are researching the dry, lifeless soil and publishing lots of scientific articles about their findings.
The soil does not have abnormal acidity or alkalinity and it is not toxic - if there would be water, it would sustain a whole set of diverse species. But until recent times it seemed that area around Yungay is completely lifeless.
Thus a group of scientists from NASA Ames Research Center have been looking for life here for several years and have found none - their collected soil samples did not contain any traces of DNA. The only organic molecules found by pyrolysis-gas chromatography-mass spectrometry method were formic acid and benzene found in very low concentrations.
Only in 2007 it has been found that some microbial life exists on the thin layer (varnish) on the surface of rocks. Areas devoid of larger rocks still are lifeless.
In 2010 there has been published another research showing that microbial life exists also in gypsum crusts which are found in some areas. But in driest locations of Yungay even in gypsum crusts there is no life.
Some species of microorganisms manage to live in the dry salt flocks which gather some moisture at dawn, when temeprature falls and air releases some moisture.
But there are locations in Yungay where none of these habitats exists. It is possible that these areas are the only lifeless grounds on Earth.