The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) instruments completed a successful series of ground tests at Ball Aerospace & Technologies Corp., Boulder, Colo. CALIPSO was then shipped to the Alcatel Space facility in Cannes, France, where the U.S. and French payload will be integrated into a Proteus spacecraft platform.

CALIPSO is expected to give the international science community a better understanding of clouds and atmospheric aerosols that influence Earth's climate. Data from CALIPSO will help create climate predictions for national and international leaders to make policy decisions about global climate change.

"One of NASA's goals is to understand how the Earth's climate system functions and is expected to change in the future," said NASA's David Winker, principal investigator for CALIPSO. "There are significant uncertainties regarding the role of clouds and aerosols in the climate system, because it's difficult to make the necessary measurements from space. CALIPSO offers a whole new way of looking at the atmosphere and overcomes many of the limitations of passive instruments. It's like the difference between an X-ray photograph and a CAT scan, he said."

The primary instrument on CALIPSO is a three-channel polarization lidar (light detection and ranging instrument) that will provide unique information on clouds and aerosols. Satellite instruments are passive. They observe scattered sunlight or emitted heat and try to infer the altitude and properties of aerosols and clouds.

CALIPSO will use a laser to actively sense where they are located, similar to the way radar works. CALIPSO underwent active laser testing in early December at Ball Aerospace's facilities. "The atmospheric test was extremely successful," said Jim Wells, NASA's Langley Research Center CALIPSO Atmospheric Test Director. "As a result, NASA has gained significant confidence in the scientific capabilities of the CALIPSO payload."

As a part of the NASA Earth System Science Pathfinder program, CALIPSO is a collaborative effort with the French space agency Centre National d'Etudes Spatiales (CNES), Ball Aerospace, Hampton University and France's Institut Pierre Simon Laplace.

Ball Aerospace is responsible for CALIPSO's scientific instrument and communications suite, including the lidar and wide field camera. CNES provided a three-channel imaging infrared radiometer, will monitor and command CALIPSO on its 36-month mission.

Final testing and launch of CALIPSO is at Vandenberg Air Force Base, Calf. CALIPSO will share the Delta II rocket in a dual configuration with NASA's CloudSat, a satellite that will use millimeter wave radar to measure cloud properties from space. Launch is planned for early 2005. CALIPSO and CloudSat will fly in orbital formation as part of a constellation of Earth-observing satellites including Aqua, PARASOL, and Aura, collectively known as the "A-train."

"Because we'll fly in formation, measurements from CALIPSO can also be used to test and improve the accuracy of cloud and aerosol measurements from the other A-train instruments," Winker said. "The height-resolved measurements of aerosols and clouds from CALIPSO will help to improve our ability to predict the severity of global warming."

CALIPSO and other Earth Observing System research is funded by NASA's Earth Science Enterprise. The Enterprise is dedicated to understanding the Earth as an integrated system and applying Earth System Science to improve prediction of climate, weather and natural hazards using the unique vantage point of space. For more information about the mission on the Internet, visit:

http://www-calipso.larc.nasa.gov/