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The US Space Surveillance Network has tracked every object in orbit over 10 cm since 1957. There are approximately 3,000 satellites in orbit, with the largest being the International Space Station. The operational lifetime of satellites is 5-20 years, and many countries and international companies have launched them for military and commercial purposes. The SSN was founded after the Soviet Union launched Sputnik in 1957, and the space race between the USSR and the USA ended with the Apollo landing in 1969.
The satellites are tracked by the United States Space Surveillance Network (SSN), which has tracked every object in orbit with a diameter greater than 10 cm (3.937 inches) since it was founded in 1957. There are approximately 3,000 satellites operating in orbit terrestrial, according to the US National Aeronautics and Space Administration (NASA), out of about 8,000 man-made objects in total. Throughout its history, the NHS has tracked more than 24,500 space objects orbiting the Earth. Most of these fell into unstable orbits and were incinerated during re-entry. The NHS also keeps track of which piece of space junk belongs to which country.
The SSN was founded in the wake of the Soviet Union’s launch of Sputnik, the first man-made satellite, in October 1957. Orbiting the planet at 20,000 mph (32,186.88 km/h) while emitting a constant radio signal, Sputnik it was a red flag telling America not to take its technological dominance for granted. In the next decade, the space race between the USSR and the USA took place, which ended with the Apollo landing in July 1969.
As space technology has matured, satellites have been launched for military and commercial purposes. The price of satellite launches has dropped to a few million dollars for light satellites and a few tens of millions for heavy satellites. This has put satellite technology within the reach of many nations and international companies.
The satellites have an operational lifetime of between five and 20 years. In 2008, the former Soviet Union and Russia had nearly 1,400 satellites in orbit, the United States about 1,000, Japan more than 100, China about 80, France more than 40, India more than 30, Germany nearly 30, the UK and Canada 25, and at least ten each from Italy, Australia, Indonesia, Brazil, Sweden, Argentina, Saudi Arabia and South Korea. The Sea Launch company — a consortium of four companies from the United States, Russia, Ukraine and Norway — has launched a few satellites into orbit from international waters every year, although the company filed for bankruptcy in 2009.
The largest artificial satellite currently orbiting the Earth is the International Space Station. Some satellites, called microsats, nanosats or picosats, can have a diameter of up to 10 cm (3.937 inches) and a mass of 0.1 kg (0.22 pounds).
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