An astronaut aboard the International Space Station took this photograph of solar evaporation ponds outside the city of Moab, Utah. There are 23 colorful ponds spread across 400 acres. They are part of a large operation to mine potassium chloride—more commonly referred to as muriate of potash (MOP)—from ore buried underground. MOP is in high demand as fertilizer because there are no easy substitutes for potassium, an essential nutrient for plant growth.