Mapping Earth’s Resources and Changes with Landsat Satellites
Since 1972, Landsat satellites have provided valuable images of Earth's surface from space. Managed by the United States Geological Survey (USGS) and National Aeronautics and Space Administration (NASA), the Landsat program has played a critical role in monitoring natural resources, tracking environmental changes, and supporting a wide range of applications, from agriculture and forestry to urban planning and emergency response. In this article, we will explore the history, technology, and applications of Landsat, and how it has revolutionized our understanding of the world.A Brief History of Landsat Satellites
The first Landsat satellite, originally named Earth Resources Technology Satellite (ERTS-1), was launched in 1972. It carried two sensors, the Return Beam Vidicon (RBV) camera and the Multispectral Scanner (MSS) instrument. The RBV camera had a resolution of 80 meters and could capture black-and-white images, while the MSS instrument had a resolution of 80 meters, with four spectral bands that could distinguish different types of land cover, such as vegetation, water, and urban areas. Since then, seven Landsat missions have been launched, with Landsat 8 currently in orbit. Landsat 8 carries two sensors, the Operational Land Imager (OLI) and the Thermal Infrared Sensor (TIRS), which can collect data in 11 spectral bands, ranging from visible and near-infrared to thermal infrared. With a resolution of 30 meters for most bands, Landsat 8 can capture more detailed and accurate images than its predecessors, and provide new opportunities for research and applications.Applications and Innovations in Landsat Imagery
Landsat imagery has been used for a wide variety of applications, including agriculture, forestry, geology, hydrology, climate research, and urban planning. For example, Landsat data can help farmers monitor crop growth and health, detect pests and diseases, and optimize irrigation and fertilization. Foresters can use Landsat data to track deforestation, wildfires, and insect infestations, and estimate timber volume and quality. Geologists can use Landsat data to map geological formations, identify mineral resources, and monitor volcanic activity. Hydrologists can use Landsat data to assess water quality and availability, monitor droughts and floods, and model water balance. Climate researchers can use Landsat data to study land surface temperature, vegetation dynamics, and carbon cycle. Urban planners can use Landsat data to analyze land use, population density, and transportation patterns, and support smart growth and resilience. In recent years, Landsat imagery has been combined with new technologies and methods, such as machine learning, cloud computing, and data fusion, to enable more efficient and accurate analysis and visualization. For example, Google Earth Engine provides free access to Landsat imagery and tools for processing and analyzing large datasets, and has been used for a wide range of research and applications, such as monitoring land cover changes, assessing deforestation risks, and predicting crop yields. Other platforms, such as Planet and Sentinel Hub, also offer Landsat data and services for various users, from researchers and developers to NGOs and governments. In conclusion, Landsat satellites have played a crucial role in advancing our understanding of Earth's resources and changes, and supporting a wide range of applications and innovations. As we face increasingly complex and urgent environmental challenges, Landsat data and technologies will continue to be a valuable resource for scientific research, policy making, and public education.