On October 4, 1957, the Soviet Union made history by launching the first Earth-orbiting artificial satellite, Sputnik 1. The launch of Sputnik was followed by the launch of Explorer 1 by the United States in 1958 and Astérix by France in 1965. By the dawn of the 21st century, nearly all the major countries of the world had their satellites orbiting the planet.
In fact, countries like the United States and Russia had launched hundreds of satellites by then, thus bringing the total count of man-made satellites to a four-digit figure. Russia alone has more than a thousand satellites in space today. While it is difficult to find out how many satellites are there in space, the estimates put this number well beyond the 2000 mark.
Some Facts about Artificial Satellites
Though the term 'satellite' can also refer to the Moon, i.e., the Earth's lone natural satellite, it is more often used to refer to man-made satellites (A.K.A. artificial satellites) orbiting the planet. There are thousands of satellites in space, each of which is assigned a specific task, right from communication and military surveillance to space exploration. While some satellites orbit the Earth along the polar orbit, others orbit it along the geostationary orbit. The average lifespan of a satellite ranges between 5 - 20 years. As the mission nears its end phase, satellite operators can either de-orbit the satellite, leave it in its orbit, or move it to the graveyard orbit. As the de-orbiting process is costly, most of the countries either leave the satellite in their current orbit or move them to the graveyard orbit.
Number of Satellites are in Space
Since it came into existence in 1957, the United States Space Surveillance Network (SSN), which has the ability of tracking any object with a diameter of 3.93 inches, has tracked more than 26,000 space objects orbiting the Earth. Of these 26,000 objects, approximately 8,000 are man-made as per the data compiled by National Aeronautics and Space Administration (NASA). The SSN has the ability to keep a track of objects ranging from pieces of spent rocket bodies, which weigh around 10 lb, to active satellites, which can weigh several tons. If the data compiled by the National Space Science Data Center is to be believed, as many as 6,578 satellites have been launched into space since 1957.
Does that mean as many as 6,578 active man-made satellites are in space at this moment? Not really. Like we said earlier, the average lifespan of a satellite ranges between 5 - 20 years. The evaluation of the data compiled by Space Surveillance Network reveals that only around 7 percent of the total objects that it is tracking, which amount to around 560, are actually active satellites, while rest are mere space debris, which include spent rocket pieces as well as defunct satellites. If the data compiled by the Goddard Space Flight Center is to be believed, there are as many as 2,271 satellites currently in orbit (both, active and defunct satellites). With a total of 1324 satellites to its credit, Russia leads the list of countries in terms of number of satellites, followed by the United States with 658 of its own.
With so many man-made satellites orbiting the planet, the chances of collision cannot be ruled out, and that was proved by the recent incident wherein the Iridium communications satellite collided with a Russian satellite. The largest artificial satellite that has ever orbited the Earth is the International Space Station (ISS), an internationally developed research facility in low Earth orbit which is expected to be completed in 2011.