CloudSat’s revolutionary radar technology
NASA’s CloudSat mission, launched in 2006, marked a turning point in understanding atmospheric dynamics with its innovative Cloud Profiling Radar, the first 94 GHz (W-band) radar ever sent to the space. This instrument, a thousand times more sensitive than terrestrial meteorological radar, has made it possible to observe clouds no longer as flat images, but as three-dimensional sections of the atmosphere rich in ice and rain.
For the first time, researchers were able to study clouds and precipitation at the same time, opening new frontiers in forecasting global weather and climate. “Without clouds, humanity would not exist, as they provide fresh water for life as we know it,” said Graeme Stephens, the mission’s principal investigator at NASA’s Jet Propulsion Laboratory in California. “Clouds have been a puzzle in terms of predicting climate change.”
The challenge of storms
Over the years, CloudSat has flown over powerful storm systems like Hurricanes Maria, Harvey and Sandy, exploring beneath their cirrhous cloud covers. Its radar has proven particularly effective in penetrating cloud layers, helping scientists to understand the mechanisms of intensification of tropical cyclones.
Despite several potentially fatal issues for the mission, related to the battery and satellite orientation control mechanisms, the CloudSat team has developed innovative solutions, such as satellite hibernation during the unlit parts of the orbit to conserve energy, and orientation with a reduced number of reaction wheels. These techniques allowed operations to continue until the radar was finally shut down in December 2023.
Twin satellites and the legacy of CloudSat
CloudSat was launched together with the CALIPSO satellite, equipped with lidar, and together they were part of an international constellation of satellites for monitoring weather and climate. Radar and lidar, considered “active” sensors, have made it possible to study the vertical structure of the atmosphere and the influence of suspended particles, such as dust, sea salt, ash and soot, on the formation of clouds.
The question of the influence of aerosols on clouds remains central to global warming projections. To explore this and other questions, the recently launched PACE satellite and future NASA Earth System Observatory missions will build on the legacy of CloudSat and CALIPSO for a new generation of studies.
“The Earth in 2030 will be different from the Earth in 2000,” Stephens said. “The world has changed, and the climate has changed. Continuing these measurements will provide us with new insights into changing weather patterns.”
The CloudSat project is managed for NASA by JPL, which developed the Cloud Profiling Radar instrument with important hardware contributions from the Canadian Space Agency. The University of Colorado manages the data processing and distribution scientific. BAE Systems of Broomfield, Colorado, designed and built the satellite. The US Space Force and the US Department of Energy contributed resources. US and international universities and research centers support the mission’s scientific team. Caltech in Pasadena, California, operates JPL for NASA.
The joint NASA-CNES CALIPSO mission concluded in August 2023.
