67 years ago today, February 1, 1958 (December 13, 1957 Calendar), the United States launched the "Explorer" 1 artificial Earth satellite. On February 1, 1958, the "Explorer" 1 was the first artificial Earth satellite in the United States, until the "Explorer" series in 1975 launched a total of 55 satellites, of which 53 entered the orbit of the "Explorer" 1 satellite, the orbital parameters of the satellite are close to 360 km, distance 2531 km, angle of 33.34 °, cycle of 114.8 minutes. On May 23, 1958, the satellites stopped working. The main tasks of this satellite series are: (1) to detect the Earth's atmosphere and ionic layer; (2) to measure the Earth's high-air magnetic field; (3) to measure solar radiation.