An artist’s concept shows NASA’s CloudSat spacecraft orbiting above Earth. Launched in 2006, it provided the world’s first study of cloud properties before being decommissioned in March 2024, at the end of its lifespan. Credit: NASA/JPL
For nearly two decades, its powerful radar has provided unprecedented detail about clouds and helped advance global weather and climate predictions.
CloudSat, a NASA The mission that scanned hurricanes, counted snowfall rates around the world and achieved other weather and climate firsts has ended operations. Originally proposed for a 22-month mission, the spacecraft was recently decommissioned after nearly 18 years of observing the vertical structure and ice and water content of clouds.
As planned, the spacecraft – having reached the end of its lifespan and no longer able to conduct regular observations – was placed last month into an orbit that will result in its eventual disintegration in the atmosphere.
NASA’s CloudSat flew over Hurricane Bill near the eastern coast of the United States in August 2009, capturing data from the Category 4 storm eye. This pair of images shows a view from the Aqua satellite of the agency (top) as well as the vertical structure of the clouds measured by CloudSat radar (bottom). Credit: Jesse Allen, NASA Earth Observatory
Revolutionary radar technology
When launched in 2006, the mission’s cloud profiling radar was the first-ever 94 GHz wavelength (W-band) radar to fly in space. A thousand times more sensitive than conventional ground-based weather radars, it gave a new view of clouds – not as flat images on a screen but as 3D slices of atmosphere bristling with ice and rain .
For the first time, scientists were able to observe clouds and precipitation together, said Graeme Stephens, the mission’s principal investigator at NASA’s Jet Propulsion Laboratory in Southern California. “Without clouds, humans would not exist, because they provide the fresh water that life as we know it requires,” he said. “We sometimes refer to them as clever little devils because of their puzzling properties. Clouds are a conundrum when it comes to predicting climate change.
In this animation, CloudSat’s radar clips Hurricane Maria as it rapidly intensified in the Atlantic Ocean in September 2017. The areas of high reflectivity, shown in red and pink, extend for more than 15 kilometers height, indicating that large quantities of water are being drawn upward into the atmosphere. Credit: NASA/JPL-Caltech/ACEI
Clouds have long held many secrets. Before CloudSat, we didn’t know how often clouds produced rain and snow on a global scale. Since its launch, we have also come a long way in understanding how clouds are able to cool and warm the atmosphere and surface, as well as how they can cause aircraft to ice.
CloudSat data has inspired thousands of research publications and continues to help scientists make key discoveries, including how much ice and water clouds contain globally and how much way in which, by trapping heat in the atmosphere, clouds accelerate the melting of ice in Greenland and at the poles.
Weather the storm
Over the years, CloudSat has flown over powerful storm systems with names like Maria, Harvey and Sandy, peeking beneath their swirling cirrus clouds. Its cloud profiling radar excelled at penetrating cloud layers to help scientists explore how and why tropical cyclones intensify.
During CloudSat’s life, several potentially mission-ending problems have arisen, related to the spacecraft’s battery and the reaction wheels used to control the satellite’s orientation. The CloudSat team has developed unique solutions, including “hibernation” of the spacecraft during the parts of each orbit where it is not daylight to save energy and steer it with fewer reaction wheels. Their solutions made it possible to continue operations until the Cloud Profiling Radar was permanently deactivated in December 2023.
“The fact that we have dedicated and talented teams who can do things that have never been done before is part of who we are as a NASA family,” said Deborah Vane, CloudSat project manager at JPL. . “We recovered from these anomalies with techniques that no one had ever used before. »
Sister satellites
CloudSat was launched on April 28, 2006, in tandem with a lidar-carrying satellite called CALIPSO (short for Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation). The two spacecraft joined an international constellation of weather and climate tracking satellites in Earth orbit.
Radar and lidar are considered “active” sensors because they direct beams of energy toward Earth – radio waves in the case of CloudSat and laser light in the case of CALIPSO – and measure how Beams reflect off clouds and fine particles (aerosols) in the atmosphere. Other scientific instruments in orbit use “passive” sensors that measure reflected sunlight or radiation emitted by Earth or clouds.
Orbiting less than a minute apart, CloudSat and CALIPSO circled the globe in sun-synchronous orbits from the North Pole to the South Pole, crossing the equator early in the afternoon and after midnight daily. Their overlapping radar-lidar fingerprints traverse the vertical structure of the atmosphere to study thin and thick clouds, as well as layers of airborne particles such as dust, sea salt, ash and soot which can influence the formation of clouds.
The influence of aerosols on clouds remains a key question for 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.
“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 give us new information on changing weather conditions.
Learn more about missions
The CloudSat project is managed for NASA by JPL. JPL developed the Cloud Profiling Radar instrument with significant hardware contributions from the Canadian Space Agency. Colorado State University provides processing and distribution of scientific data. BAE Systems of Broomfield, Colorado, designed and built the spacecraft. The US Space Force and the US Department of Energy contributed resources. American and international universities and research centers support the mission’s scientific team. Caltech in Pasadena, California, manages JPL for NASA.
CALIPSO, which was a joint mission of NASA and the French space agency, CNES (Centre National d’Études Spatiales), completed its mission in August 2023.
