Saudi Arabia is drilling for a resource possibly more precious than oil. Over the last 24 years, it has tapped hidden reserves of water to grow wheat and other crops in the Syrian Desert. This time series of data shows images acquired by three different Landsat satellites operated by NASA and the U.S. Geological Survey. In this series of four Landsat images, the agricultural fields are about one kilometer across. Healthy vegetation appears bright green while dry vegetation appears orange. Barren soil is a dark pink, and urban areas, like the town of Tubarjal at the top of each image, have a purple hue. Credit: NASA/GSFC The green fields that dot the desert draw on water that in part was trapped during the last Ice Age. In addition to rainwater that fell over several hundred thousand years, this fossil water filled aquifers that are now buried deep under the desert's shifting sands. Saudi Arabia reaches these underground rivers and lakes by drilling through the desert floor,...