A technique called interferometric synthetic aperture radar (InSAR), used to detect tiny movements of Earth’s surface from space, is taking off. Individual GPS stations can track surface movements of less than 1 millimeter, but InSAR can measure changes almost as subtle across a swath hundreds of kilometers wide. With InSAR, scientists are tracking how ice streams flow, how faults slip in earthquakes, and how the ground moves as fluids are pumped in or out. And the flood of InSAR data is growing fast. Since 2018, the number of civil and commercial SAR satellites in orbit has more than doubled. And at least a dozen more are set to launch this year, which would bring the total to more than 60. With the help of computing advances that make data processing easier, the satellite fleets may soon be able to detect daily or even hourly surface changes at just about every patch of ground on Earth. And that will enable new applications: near–real-time monitoring of the structural integrity of dams and buildings, along with disaster response efforts for floods and fires. Analysts value the SAR market at roughly $4 billion and expect that figure to nearly double over the next 5 years. Many believe InSAR will eventually underpin our daily lives.