ESSP (Earth System Science Pathfinder) Program is a component of NASA's Earth Science Enterprise. ESSP manages, directs, and implements low- to moderate-cost, rapidly-developed science missions, the primary goal of which is to investigate global climatic change. The first missions in the Program are GRACE (Gravity Recovery and Climate Experiment), launched on March 17, 2002; CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations), scheduled for launch in April 2005; CloudSat, scheuled for launch in April 2005; OCO (Orbiting Carbon Observatory), scheduled for launch in August 2007; Aquarius, scheduled for launch in September 2008; and HYDROS (Hydrosphere State Mission), scheduled for launch December 2010. Development of an earlier ESSP mission, VCL (Vegetation Canopy Lidar), was suspended.