The Calipso (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite bservation) satellite, for which Alcatel Alenia Space handled spacecraft-payload integration, will be launched on April 21, from the Vandenberg Air Force Base in California, using a Boeing Delta 2 rocket.

The Calipso mission is part of a joint program between the French space agency CNES and the National Aeornautics and Space Administration, and will be launched along with the Cloudsat satellite.

The Calipso satellite will help scientists better understand the climatic system and predict changes, an ability which is currently limited by ncertainties about the radiation impact of clouds and aerosols. In particular, it will provide a unique dataset on the vertical distribution of clouds and aerosols, to be measured by the first spaceborne backscatter lidar (LIght Detection And Ranging, a sort of laser radar). The satellite’s design life is three years.

Calipso is part of a global French-American climate study program, and ill be orbiting in formation, no more than a few minutes apart, with the two satellites Aqua and Cloudsat, and the French microsatellite Parasol.

Dubbed the "A-Train", this constellation forms an exceptional spaceborne observatory. It will be placed in sun-synchronous orbit at an altitude of 705 kilometers (438 miles). The A-Train combines a full slate of active and passive measurement techniques to study the Earth’s climate and interactions between radiation, clouds, aerosols and the water cycle. An unrivaled observatory, it will be able to test and improve digital forecasting models, covering both weather and pollution aspects of our climate.

With this dual launch, the constellation will comprise five satellites:

Aqua was launched in April 2002 and has a nominal lifespan of five years, while Aura was launched in July 2004, Parasol in December 2004, Cloudsat and Calipso, scheduled for April 21.

The main industrial partners in this mission are Alcatel Alenia Space and Ball Aerospace. Following Jason-1, launched in December 2001, Calipso is the second low-orbit minisatellite developed using the Proteus multimission platform (a reconfigurable platform for observation, telecom and science missions). It was designed by Alcatel Alenia Space as prime contractor, in collaboration with CNES.

The upcoming satellites built by Alcatel Alenia Space using the Proteus platform are Corot, slated for launch this year, SMOS in 2007 and Jason-2 in 2008.