NASA's Advanced Topographic Laser Altimeter System (ATLAS) is a laser altimeter aboard the Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2) platform. ATLAS has three primary tasks: Send pulses of laser light to the ground, collect the returning packets of electromagnetic radiation (called photons), and record the photon travel time. The instrument measures height about every 2.3 feet along the satellite’s path and can measure surface height to a precision of approximately one inch (about the length of a standard paperclip). While the primary intent of ATLAS is to measure cryospheric elevation, the instrument is able to measure elevation in temperate regions, including measurements of forest cover and vegetation, and is even able to detect water features such as coral reefs and ocean waves.