US: Launched on April 15, 1999, the Landsat 7 satellite has now been observing Earth from outer space for 15 years. The Landsat program is a decades-long NASA and US Geological Survey (USGS) partnership that has provided a continuous record of change across the earth land surface since 1972.
The satellite was designed to last only 3 to 5 years but continues to provide important information about the land surface of the planet. Landsat 7′s companion satellite, Landsat 5, recently achieved 25 years of operation, which surpassed its designed life expectancy by 22 years.
Landsat 7’s remarkable longevity has been vital to the majority of Landsat data users who require frequent imaging of specific areas for land and resource management. For example, water resource managers in western US states need Landsat’s unique combination of thermal and vegetation condition readings at field scale to estimate water use more efficiently for crop irrigation — typically the major source of water consumption in these arid regions.
Combined with Landsat 8, Landsat 7 ensures the collection of images across the entire US every eight days and enables the collection of critical global imagery sets on a seasonal basis. Working in tandem, Landsat 7 and Landsat 8 together collect nearly 1000 images daily, almost double the amount of data collected when Landsat 5 and 7 were operating together. This increased data collection benefits all Landsat applications, especially in persistently cloudy areas (e.g. humid tropics and high latitudes) where multiple imaging attempts are essential. NASA and the USGS are working together on a plan to ensure long-term continuity of land imaging operations while also addressing the near-term need to replace Landsat 7.