Terra, launched on 18th December 1999, is a polar-orbiting satellite within the Morning Constellation that have equator crossings around 10:30 and 22:30 under NASA's Earth Obseration System (EOS).

On February 24, 2000, Terra began collecting what was aimed to ultimately become a new, 15-year global data set on which to base scientific investigations about our complex home planet. Together with the entire fleet of EOS spacecraft, Terra is helping scientists unravel the mysteries of climate and environmental change.

The satellite carries the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), the Clouds and Earth's Radiant Energy System (CERES), the Measurements of Pollution in the Troposphere (MOPITT), the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Multi-angle Imaging Spectroradiometer (MISR), and these collect data on the Earth's atmosphere, ocean, land, snow and ice, and energy budget.