In 1957, the Soviet Union launched the first man-made satellite. Because at that time space technology was in its infancy, it was hard to get an exact fix on the satellite's orbit.
西元一九五七年，蘇俄發射第一顆人造衛星進入太空，由於當時太空科技剛起步，無法精確掌握人造衛星運行的軌道，且極有掉落的可能。