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CALIPSO and CloudSat: Dancing Around Earth

February 26, 2005

NASA — Most of us only pay attention to clouds when trying to plan a picnic or an outside activity. But to scientists, they mean much more. Clouds affect temperatures and air quality across the globe and play a crucial role in the planet’s climate.

Clouds are the link between energy and water in the Earth’s climate system; they dominate the energy budget of the Earth and carry the precipitation that redistributes fresh water on the Earth’s surface.

To aid our stewardship of Earth, we need to know how to better manage the air quality. We can’t say with any certainty what increasing carbon dioxide will do to the Earth’s climate unless we can improve the way that clouds and aerosols are represented in climate models.

Even small changes in the amount of cloudiness can profoundly change the way the Earth’s climate responds to increased greenhouse gases or aerosols in the atmosphere.

NASA will look to the suite of instruments on two new satellites: CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) and CloudSat to help Earth’s leaders make better policy decisions in response to global climate changes.

The satellites are scheduled for launch no earlier than mid-June from Vandenberg Air Force Base in California aboard the same Delta II rocket.

Scientists need to know the composition of cloud condensation nuclei, the amount of water and ice in clouds, the height of clouds in the sky and the extent to which clouds at different altitudes overlap each other. These factors affect the distribution of heating within the atmosphere and at the surface of the Earth, influencing the circulation of the atmosphere and of the ocean. This is because the balance between incoming sunlight and outgoing energy determines the planet’s temperature and ultimately, its climate.

CALIPSO and CloudSat will join a carefully choreographed dance of satellites. The duo will fly in orbital formation with NASA’s Earth-observing satellites Aqua and Aura, and with PARASOL, a satellite developed by the French space agency, Centre National d’Etudes Spatiales (CNES). Collectively, the satellites are known as the “A-train” after the famous jazz tune.

Measurements from CALIPSO and CloudSat will be used to test and improve the accuracy of cloud and aerosol measurements from the other A-train satellites, according to David Winker, NASA’s principal investigator for CALIPSO and Graeme Stephens, NASA’s Principal Investigator for CloudSat.

Within the first 30 days of the launch, CloudSat will be maneuvered into formation to maintain a precise distance and time separation from CALIPSO creating a “virtual” spacecraft platform.

The CloudSat Mission is a partnership between Colorado State Univerity, the Jet Propulsion Laboratory in California, the Canadian Space Agency, the U.S. Air Force and the U.S. Department of Energy. Ball Aerospace & Technologies Corp. built the spacecraft.

Image right: CloudSat will make key measurements that will advance our limited understanding of cloud-climate feedback. Credit: NASA/Colorado State University

NASA’s Langley Research Center in Virginia is leading the CALIPSO mission, providing overall project management and collaborating with NASA’s Goddard Space Flight Center in Maryland, CNES, Ball Aerospace, Hampton University and the Institut Pierre Simon Laplace in France.

One of NASA’s goals is to understand the effects of natural and human-made hazards on the atmosphere and predict the effects of climate change. Scientists who learn new ways to improve conditions on Earth may use that knowledge to monitor the health of other planets as we travel to the Moon, Mars and beyond.


CALIPSO and CloudSat Dancing Around Earth


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