In (Ding the twelfth lunar month 13), February 1, 1958, the United States launched the 1st artificial Earth satellite "Explorer". February

1958, the United States launched the "explorers" No. 1, the first artificial Earth satellite, "Explorer" series in 1975 launched a total of 55 satellites, of which 53 to enter track.
"explorers" No. 1 satellite orbit parameters perigee of 360 km, apogee 2531 km, inclination of 33.34 �� cycle of 114.8 minutes. May 23, 1958 satellite stopped working. This satellite series
main task is to: (1) to detect the Earth's atmosphere and ionosphere; (b) measuring the Earth's high-altitude magnetic field; (3) to measure solar radiation. The solar wind and the Sun-Earth relationship; (4) detection of interstellar space; (5) the detection and study of cosmic rays and the rapids of stars; (6) determination of the shape of the Earth and the Earth's gravitational field. [����d��y����h�� $ �Ө�ry.c��m]