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Salar de Coipasa salt lake from the air

Photo: NASA earth observatory

Without sunglasses, it is difficult for people to even recognize Bolivia's salt flats. The endless white background, flat as a flounder, reflects the light so strongly in good weather that the surroundings easily merge into a garish mush.

The landscape here, in the southwest of Bolivia on the border with Chile, is spectacular: In the middle of the peaks of the Altiplano highlands at an altitude of more than 3600 meters lies the salt lake Salar de Coipasa, in the center of the picture. And its larger neighbor Salar de Uyuni (right), the largest so-called salt pan on earth. The Coipasa already has an area of more than 2200 square kilometers, that of the Uyuni is almost five times as large. The two plains, separated by a volcanic massif, were formed when a large lake dried up about 10,000 years ago.

Today, the salt crusts of the two basins are up to ten meters thick. They form a stark contrast to the barren, brown peaks of the Andes that surround them. The lakes collect water only in the rainy season between January and March, then it stands a few centimeters high and transforms the surface into huge mirrors that reflect the mountains during the day and the stars at night. Photographers are then offered unique motifs. The picture above is from the beginning of May, apparently there is still some water on the salt surface.

However, this will change as the year progresses. In August, the salt desert is dry, the water has evaporated. That's when tourists in jeeps like to venture onto the fields and bring some guests to the few hundred inhabitants of Coipasa, a town on the island in the lake.

There are even hotels made entirely of salt at the Salar de Uyuni, even the beds are made of them. The population also earns a living by working in the Salinas, the salt mining sites. About 25,000 tons of the raw material are extracted here every year, mostly by hand.

In the end, however, it was another resource that aroused desire: lithium. The silvery-white, particularly conductive light metal, which is so important for battery production, is found in both lakes. The deposit at the Salar de Uyuni is considered one of the largest in the world. According to data from the U.S. Geological Survey, millions of tons of lithium are located here.

So far, plans for mining in the remote region have failed. An agreement with a German company on the exploitation of the deposits did not materialize and fell victim to the political turmoil caused by the ousted ex-president Evo Morales. Subsequently, it was hoped for a renewal of the deal. But most recently, a Chinese consortium was awarded the contract.

Salt lakes in the focus of space exploration

But Uyuni and Coipasa are interesting for other reasons. As the U.S. space agency Nasa writes, the lakes are something like natural laboratories for exploring the Martian environment. The clays and mineral brines are comparable to those of the Red Planet. For this reason, the region offers insights into processes that could also play a role on Mars.

The geology and geochemistry at the Salar de Uyuni can be compared to that of the Aureum Chaos, a large basin on the surface of Mars. Before future Mars missions, Nasa may take a closer look at the lakes. Perhaps this is also the reason why an astronaut on board the International Space Station ISS took the picture with his digital camera.