NASA's Perseverance rover has revealed an ancient subsurface river delta under its ground-penetrating radar, RIMFAX. The rover's primary mission is to search for signs of ancient life in Jezero Crater in 2021. The radar, which continuously fires radar waves into the ground, acquired soundings each time the rover traveled 10 centimeters. This discovery allows scientists to construct a two-dimensional, vertical slice of the subsurfaced. The discovery was led by Emily L. Cardarelli, an astrobiologist at the University of California Los Angeles.