Keeping watch

-- Satellites perform a number of roles in modern society. According to the Washington Post , communications in the United States were disrupted when the Galaxy 4 satellite spun out of position recently throwing everything into confusion. This event illustrates how much communication relies today on satellites. Galaxy 4 is one of more than 260 commercial satellites operating that make global TV, radio and telephone signals possible. Apart from satellites for communications, there are 40 civilian satellites for Earth observation and meteorological purposes, and at least 100 military satellites on reconnaissance and early-warning missions which circle the Earth.