53 years ago today, on July 23, 1972 (June 13, 1972 lunar calendar), the United States launched the first earth resource technology satellite. The United States launched the first earth resource technology satellite, referred to as ERTS, on July 23, 1972. Two years later, it was renamed Landsat. Since then, in 1975, four Landsat 2 to Landsat 5 have been launched successively. Due to the characteristics of high imaging accuracy, large coverage area, and superiority of time and spectral resolution, Landsat images and data are widely used by countries all over the world. Most of the information sources for the development and utilization of natural resources in our country's "Seventh Five-Year" scientific research projects basically use Landsat image data and numerical information as materials. Due to the relatively reliable scientific and economic nature of its images, ground receiving stations have been established in more than a dozen countries such as China and Japan to facilitate timely receipt of data (without the need to order images from the United States). Since the satellite was launched, remote sensing yield estimation, remote sensing fishing, and remote sensing prospecting have entered a new era. In the late 1970s, the United States' remote sensing yield estimation of Soviet wheat reached 94% accuracy, which caused a sensation in the whole world, thus setting off a remote sensing frenzy, which is directly related to land satellite image data. Therefore, the remote sensing community called the successful launch of the first US earth resources technology satellite a new milestone in the history of spaceflight.