Landsat

Landsat
Name	Landsat
Mission type	Earth observation satellite
Operator	NASA / USGS
Website	https://landsat.gsfc.nasa.gov/

Landsat is the world's longest-running enterprise for acquisition of satellite imagery of Earth. It is a joint program between the National Aeronautics and Space Administration and the United States Geological Survey. Since the launch of Landsat 1 in 1972, the mission has provided a continuous, multispectral record of the planet's surface, enabling transformative studies in geography, forestry, agriculture, and climate science.

Overview

The program was conceived during the early days of the Space Race to systematically observe Earth from space. Managed through a partnership between NASA and the USGS, it represents a cornerstone of civilian remote sensing. Data from the constellation is used globally by researchers in institutions like the European Space Agency and governments across Asia and Africa. The continuous archive, maintained by the Earth Resources Observation and Science Center, serves as an invaluable tool for monitoring deforestation in the Amazon rainforest and urban sprawl around megacities like Tokyo.

History and development

The origins trace to proposals like the Earth Resources Observation Satellite program in the 1960s. The success of Landsat 1, originally named the Earth Resources Technology Satellite, demonstrated the practical value of space-based observation. Subsequent missions, including Landsat 4 and Landsat 5, introduced advanced sensors like the Thematic Mapper. A significant policy shift occurred with the Landsat Remote Sensing Policy Act of 1992, which commercialized operations under Space Imaging before management returned to the USGS. The launch of Landsat 7 in 1999 and Landsat 8 in 2013 ensured data continuity.

Satellites and sensors

Each satellite has carried progressively more sophisticated instrumentation. Early missions, such as Landsat 1 through Landsat 3, were equipped with the Return Beam Vidicon and the Multispectral Scanner System. The Landsat 4 mission marked a major advancement with the Thematic Mapper, providing improved spatial and spectral resolution. Landsat 7 carried the Enhanced Thematic Mapper Plus, while Landsat 8 features the Operational Land Imager and the Thermal Infrared Sensor. The latest, Landsat 9, launched in 2021, continues this legacy with upgraded copies of its predecessor's instruments.

Data characteristics and applications

Data is characterized by a spatial resolution ranging from 15 to 60 meters across multiple spectral bands, including visible light, near-infrared, and thermal infrared. This enables diverse applications, such as tracking glacier retreat on the Greenland ice sheet, assessing crop health across the Midwestern United States, and managing water resources in arid regions like the Sahara. Scientists use the data to study phenology in the Siberian taiga and map damage from events like the 2011 Tōhoku earthquake and tsunami.

Data access and policy

Following the Landsat Data Continuity Mission policy, all archived and new imagery is available free of charge to users worldwide via portals like EarthExplorer. This open-access policy, established in 2008, revolutionized the field of geospatial analysis by removing cost barriers. Data is processed and distributed by the USGS at facilities like the Sioux Falls EROS Center. This policy has been adopted as a model by other programs, including the Copernicus Programme operated by the European Union.

Impact and legacy

The program has fundamentally shaped modern environmental monitoring and earth system science. Its uninterrupted record is critical for the work of the Intergovernmental Panel on Climate Change and for international treaties like the Paris Agreement. The long-term data set is indispensable for documenting the decline of the Aral Sea and the expansion of Shanghai. It has also spawned commercial sectors and inspired subsequent constellations, such as the Sentinel-2 mission. The archive stands as an enduring global public good.

Category:Earth observation satellites of the United States Category:NASA programs Category:Remote sensing