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The first satellite to explore the Earth: How did Landsat 1 start the era of remote sensing?
On July 23, 1972, with the successful launch of the US Landsat 1 satellite, Earth observation entered a new era. The satellite, originally named ERTS-A, was tasked with not only collecting data about the Earth but also pioneering remote sensing technology.
Landsat 1 was the first satellite to carry a multispectral scanner, an innovation that allowed scientists to more accurately analyze various resources on the Earth's surface.
Background
In 1966, the U.S. Department of the Interior launched the multi-agency Landsat program to collect Earth data using remote sensing technology. The feasibility study that followed did not provide funding for the satellite, but it paved the way for the subsequent Landsat program.
Satellite Design
Development
Studies that defined two Earth observation satellites began in 1967, culminating in the selection of General Electric as prime contractor for ERTS-A, with production to be performed at its Pennsylvania facility.
Operation
The satellite is about 3 meters high and 1.5 meters in diameter. It is equipped with two 4-meter-long solar panels that can continuously supply energy. Its main propulsion system consists of three hydrohydrazine thrusters and is equipped with an attitude control system to ensure that the satellite's stability in three axes is within the range of ±0.7 degrees.
Sensors
Landsat 1 carried two main imaging instruments: the echo camera (RBV) and the multispectral scanner (MSS). RBV is used to capture visible light and near-infrared images, while MSS is used for more in-depth environmental analysis.
Missions
After launching from Vandenberg Air Force Base in California, the satellite entered a sun-synchronous orbit that circles the Earth every 103 minutes. In 1975, NASA renamed it Landsat 1, and ERTS-B was named Landsat 2 that year.
Results
From its launch to 1974, Landsat 1 transmitted more than 100,000 images covering more than 75% of the Earth's surface. In the process of analyzing these images, the scientific community discovered a lot of important information, including a small uninhabited island discovered in 1976, which was later named Landsat Island.
The images sent back by Landsat 1 are widely used in the study of the Global Non-Deep Vegetation Index (NDVI), which has now become an important indicator for measuring plant growth.
Landsat 1 was officially retired in 1978 after its videotape recorder malfunctioned, but its data and methods continue to guide the future of Earth science and environmental research.
Overall, Landsat 1 was not just a satellite, but the beginning of a more comprehensive understanding of the Earth's environment. From here, how can technology better serve environmental protection and sustainable use of resources?
