English: NASA’s Ingenuity Mars Helicopter took these images on its fourth flight, on April 30, 2021, using its navigation camera. The camera, which tracks surface features below the helicopter, takes images at a rate at which the helicopter’s blades appear frozen in place, despite making 21 full rotations in-between each image. In flight, the blades spin at 2,537 rpm. The images are aligned entirely using Ingenuity's on-board position tracking system highlighting the stability and accuracy of the navigation algorithm. The Ingenuity Mars Helicopter was built by JPL, which also manages the technology demonstration project for NASA Headquarters. It is supported by NASA’s Science, Aeronautics Research, and Space Technology mission directorates. NASA’s Ames Research Center in California’s Silicon Valley, and NASA’s Langley Research Center in Hampton, Virginia, provided significant flight performance analysis and technical assistance during Ingenuity’s development. AeroVironment Inc., Qualcomm, and SolAero also provided design assistance and major vehicle components. Lockheed Martin Space designed and manufactured the Mars Helicopter Delivery System.