Landsat 7

An unprecedented enterprise began 40 years ago when the Earth Resources Technology Satellite—later renamed Landsat—was launched. Five more Landsat spacecraft would reach orbit during the next 27 years. All were launched from Vandenberg Air Force Base, Calif. into near-polar orbits, allowing them to image the entire Earth, one slice at a time, as it rotated below, and Lockheed Martin built every spacecraft at its Valley Forge, Pa., facility.
The Defense Meteorological Satellite Program (DMSP)
Landsat’s 40-year collection of land images serves those who observe and study the Earth, who manage and utilize its natural resources, and who monitor the changes brought on by natural processes and human activities. The data from Landsat spacecraft constitute the longest moderate spatial resolution multispectral record of Earth’s continental surfaces as seen from space and the only such data set with near global coverage every year. The record is unmatched in quality, detail, coverage, and value.