Why the world's largest salt flat is essential for calibrating our satellites

Nature · Published 3 October 2026 Swipe more like this →

In short: Salt flats are more than just blindingly white desert expanses. These ancient, mineral-rich basins are formed when water evaporates faster than it falls, leaving behind vast, flat crusts. Beyond their stark beauty, these geological oddities serve as critical tools for modern space technology and hold massive reserves of essential minerals.

A salt flat is a natural, open expanse of ground coated in minerals, typically appearing as a brilliant white surface that reflects sunlight. These formations arise in arid environments where the rate of evaporation consistently outpaces precipitation. When water collects in a basin with no drainage, it sits on the surface until it vanishes, leaving behind concentrated salt ions. Over millennia, these minerals build up, creating the distinct, flat landscapes found in deserts worldwide.

These environments are deceptively complex. While they appear solid, the salt crust can hide treacherous mud traps capable of swallowing heavy vehicles. Historically, these features were used as strategic barriers; during World War II, the Qattara Depression in the Sahara served this purpose. Conversely, the extreme flatness and clear skies of the Salar de Uyuni in Bolivia provide a unique utility: it is an ideal site for calibrating the altimeters of Earth observation satellites.

Beyond their role in science, salt flats are significant economic and ecological zones. The Salar de Uyuni is particularly notable for its lithium deposits. As of 2024, Bolivia is estimated to hold roughly 22% of the world's known lithium resources, totaling approximately 23 million tons out of a global 105 million tons. Other regions, such as the Rann of Kutch in India, demonstrate the seasonal versatility of these landscapes, shifting between salt marsh and salt pan depending on the time of year.

Distinguishing these natural formations from artificial salt evaporation ponds is important. While both involve mineral accumulation, natural flats are geological features of desert basins. Other related terms, such as sabkhas or dry lakes, describe variations of these closed drainage systems. Whether they are serving as testing grounds for land speed records in Utah or as vital mineral reservoirs, salt flats remain one of the most intriguing and functional landscapes on the planet.

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