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The puzzle of the Earth: How does Landsat 7 images turn into amazing vision on Google Maps?
Landsat 7 is the seventh satellite managed and operated by the U.S. Geological Survey (USGS), launched on April 15, 1999 to refresh the archives of satellite photos around the world and provide the latest cloudless images.The satellite not only provides decades of data on earth's environmental changes, but also provides important support for scientific research, environmental monitoring and urban planning.
Advances in satellite imaging technology allow us to observe and understand our planet from an unprecedented perspective.
Satellite Specifications
The Landsat 7 has a five-year design life, but it has been in operation for more than twenty years due to its outstanding performance.The satellite can collect and broadcast up to 532 images every day, scanning the surface of the earth at its altitude of 705 kilometers.The satellite weighs 1973 kilograms, is 4.04 meters long and 2.74 meters in diameter. It makes full use of its onboard's 378 Gbits solid-state memory and can store about 100 images.
Main Instruments
The main instrument equipped with Landsat 7 is the Enhanced Theme Detector (ETM+), which is a scanning image sensor.The satellite has up to eight channels that can display images from blue, green to red, near and mid-infrared.
Such a configuration allows Landsat 7 to fully capture a variety of spectral information on the Earth's surface and monitor various natural and man-made phenomena.
Failed by scanning line corrector
However, on May 31, 2003, Landsat 7's Scan Line Corrector (SLC) failed, causing the image to become unstable, and the image moves in a "jagged shape" way, plus about 22% of the Data is missing in the image.Nevertheless, through expert evaluation, these can still be used in many scientific research.
Application of satellite image
Landsat 7 images are widely used on various digital platforms, including Google Maps and NASA WorldWind.These platforms use Landsat's data to provide detailed visual information about the earth, allowing us to query geographic information easily and quickly.
Such data flow not only enriches the user's geographical experience, but also demonstrates its value in disaster management, agricultural monitoring, etc.
Road Adjustment and Future Outlook
The Landsat 7 track can be adjusted to maintain the accuracy of its data, which was last performed on February 7, 2017.However, since then, the orbit of the satellite has begun to gradually decrease and has deviated to 9:15 AM observation time in 2021.With the advent of Landsat 9, Landsat 7 will gradually terminate its scientific mission.
Conclusion
Landsat 7 is not only a satellite, but also a key tool for humans to understand and protect our planet.With the development of science and technology, how will future satellites allow us to observe and understand this planet where we live together in a more specific way?
