The first European to cross the forbidding waste was Diego de Almagro, the Spanish conquistador, in 1537. From then until the middle of the 19th cent. it was largely ignored, but with the discovery of the use of sodium nitrate as a fertilizer and later with the invention of smokeless powder using nitroglycerin, the desert had a mining boom. Although the southern half of Atacama belonged to Bolivia, the companies exploiting the deposits were Chilean. Differences arose, and in the ensuing war (see Pacific, War of the), Chile won the entire area. When synthetic nitrates were developed after World War I, the boom collapsed. Economically, the Atacama is declining, as reserves are depleted and the desert expands southward into once arable land.
The Atacama Desert is a virtually rainless plateau in South America, covering a 966 km (600 mi) strip of land on the Pacific coast of South America, west of the Andes mountains. The rain shadow on the leeward side of the Andes keeps this over 20 million-year-old desert 50 times drier than California's Death Valley. It is the second-driest desert in the world, after the McMurdo Dry Valleys of Antarctica. The Atacama occupies 181,300 square kilometers (70,000 mi²) in northern Chile, composed mostly of salt basins (salares), sand, and lava flows.
Some locations in the Atacama do receive a marine fog known locally as the Camanchaca, providing sufficient moisture for hypolithic algae, lichens and even some cacti. But in the region that is in the "fog shadow" of the high coastal crest-line, which averages 3,000 m height for about 100 km south of Antofagasta, the soil has been compared to that of Mars. Due to its otherworldly appearance, the Atacama has been used as a location for filming Mars scenes, most notably in the television series Space Odyssey: Voyage to the Planets.
In 2003, a team of researchers published a report in Science magazine titled "Mars-like Soils in the Atacama Desert, Chile, and the Dry Limit of Microbial Life" in which they duplicated the tests used by the Viking 1 and Viking 2 Mars landers to detect life, and were unable to detect any signs in Atacama Desert soil. The region may be unique on Earth in this regard and is being used by NASA to test instruments for future Mars missions. In 2008, the Phoenix Mars Lander detected perchlorates on the surface of Mars at the same site where water was first discovered. Perchlorates are also found in the Atacama and associated nitrate deposits have contained organics, leading to speculation that signs of life on Mars are not incompatible with percholates. Alonso de Ercilla described the desert in La Araucana, published in 1569: "Towards Atacama, near the deserted coast, you see a land without men, where there is not a bird, not a beast, nor a tree, nor any vegetation" (quoted Braudel 1984 p 388).
During the 19th century the desert came under control of Bolivia, Chile and Peru and soon became a zone of conflict due to unclear borders and the discovery of nitrate there. After the War of the Pacific, in which Chile annexed most of the desert, cities along the coast developed into international ports, and many Chilean workers migrated there.
The Escondida Mine and Chuquicamata are also located within the Atacama Desert.
The Pan-American Highway runs through the Atacama in a north-south trajectory.
A new radio astronomy observatory, called ALMA, is being built in the Atacama by astronomers from Europe, Japan, and North America. Another radio astronomy observatory, ACT, is being built on Cerro Toco in the Atacama Desert.
The desert has rich deposits of copper and other minerals, and the world's largest natural supply of sodium nitrate, which was mined on a large scale until the early 1940s. The Atacama border dispute over these resources between Chile and Bolivia began in the 1800s.
Now the desert is littered with approximately 170 abandoned nitrate (or "saltpeter") mining towns, almost all of which were shut down decades after the invention of synthetic nitrate in Germany at the turn of the 20th century (see Haber Process). The towns include Chacabuco, Humberstone, Santa Laura, Pedro de Valdivia, Puelma, Maria Elena and Oficina Anita.
One of the best examples of an abandoned mining town is that of Baquedano, which was home to one of the most technologically advanced train stations during the nitrate "white gold" boom of the early 20th century. While it is now almost completely abandoned, the remains of the station are untouched and seldom visited by outsiders. Only a few kilometers from Baquedano, on the Pan-American highway, is one of many makeshift cemeteries housing the remains of indigenous miners who were persuaded to work for the German mining operations. Many of the graves belong to children under the age of five, poisoned by the pollution kicked up during the mining process.