NASA’s CALIPSO mission stops blasting lasers at Earth after 17 years

The Lidar and radar instruments on the satellite direct beams of energy at Earth and measure how they reflect off the clouds and the aerosols in the atmosphere. Other orbiting science experiments typically use passive sensors that measure the sunlight or other radiation reflected by the Earth or clouds.

The two satellites were launched on April 28, 2003, and they circled the planet in a Sun-synchronous orbit from the North to the South poles. This meant that they crossed the equator in the early afternoon every day. They measured the altitude of clouds and layers of airborne particles like dust, sea salt, ash and soot while probing the “vertical structure” of the atmosphere.

The observations from the two satellites allowed scientists to build more sophisticated models to understand complex atmospheric processes like cloud formation, atmospheric convection, precipitation and particle transport. This was especially useful in situations like during the massive wildfires in Australia in 2020.

At that time, CALIPS observed smoke rising to between 15 and 20 kilometres above the Earth;s surface, high enough to reach the stratosphere, making them some of the highest plumes ever recorded.