CALIPSO was a joint NASA (US) and CNES (France) environmental satellite, built in the Cannes Mandelieu Space Center, which was launched atop a Delta II rocket on April 28, 2006.

Its name stands for Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations.

Passive and active remote sensing instruments on board the CALIPSO satellite monitored aerosols and clouds 24 hours a day.

CALIPSO was part of the "C-Train" alongside CloudSat, orbiting on a similar track to the "A-Train."

[1] Three instruments: In February 2009, CALIPSO switched over to the redundant laser as scheduled.