Unraveling the Mystery of NASA's Green Laser Beams

A Japanese astronomer, Daichi Fujii, captured footage of NASA's ICESat-2 satellite firing laser beams at Earth using a homemade motion detection camera. The satellite uses lidar to measure the height of Earth's ice, water, and land surfaces from space. The laser instrument fires 10,000 times a second, sending six beams to Earth to measure how long it takes individual photons to bounce off the surfaces and come back to the satellite. The footage marks the first time that the ICESat-2 team has ever seen footage of the satellite's green laser beams from Earth.