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If the satellites when destroyed will they came into the earth?
Space debris, also known as orbital debris, space junk, and space waste, is the collection of defunct objects in orbit around Earth. This includes everything from spent rocket stages, old satellites, fragments from disintegration, erosion, and collisions. Since orbits overlap with new spacecraft, debris may collide with operational spacecraft.

Currently about 19,000 pieces of debris larger than 5 cm are tracked,with another 300,000 pieces smaller than 1 cm below 2000 km altitude.For comparison, ISS orbits in the 300–400 km range and both the 2009 collision and 2007 antisat test events occurred at between 800–900 km.

Most space debris is less than 1 cm (0.39 in), including dust from solid rocket motors, surface degradation products such as paint flakes, and coolant released by RORSAT nuclear-powered satellites. Impacts of these particles cause erosive damage, similar to sandblasting.

Damage can be reduced with "Whipple shield", which, for example, protects some parts of the International Space Station. However, not all parts of a spacecraft may be protected in this manner, e.g. solar panels and optical devices (such as telescopes, or star trackers), and these components are subject to constant wear by debris and micrometeoroids. The flux of space debris is greater than meteroids below 2000 km altitude for most sizes circa 2012.

Safety from debris over 10 cm (3.9 in), comes from maneuvering a spacecraft to avoid a collision. If a collision occurs, resulting fragments over 1 kg (2.2 lb) can become an additional collision risk. As the chance of collision is influenced by the number of objects in space, there is a critical density where the creation of new debris occurs faster than the various natural forces remove them. Beyond this point a runaway chain reaction may occur that pulverizes everything in orbit, including functioning satellites. Called the "Kessler syndrome", there is debate if the critical density has already been reached in certain orbital bands

A runaway Kessler syndrome would render the useful polar-orbiting bands difficult to use, and greatly increase the cost of space launches and missions. Measurement, growth mitigation and active removal of space debris are activities within the space industry today.

Hazard on Earth

Saudi officials inspect a crashed PAM-D module, January 2001.

Although most debris will burn up in the atmosphere, larger objects can reach the ground intact and present a risk.

The original re-entry plan for Skylab called for the station to remain in space for 8 to 10 years after its final mission in February 1974. Unexpectedly high solar activity expanded the upper atmosphere resulting in higher than expected drag on space station bringing its orbit closer to Earth than planned. On 11 July 1979, Skylab re-entered the Earth's atmosphere and disintegrated, raining debris harmlessly along a path extending over the southern Indian Ocean and sparsely populated areas of Western Australia.

On 12 January 2001, a Star 48 Payload Assist Module (PAM-D) rocket upper stage re-entered the atmosphere after a "catastrophic orbital decay".The PAM-D stage crashed in the sparsely populated Saudi Arabian desert. It was positively identified as the upper-stage rocket for NAVSTAR 32, a GPS satellite launched in 1993.

The Columbia disaster in 2003 demonstrated this risk, as large portions of the spacecraft reached the ground. In some cases entire equipment systems were left intact.NASA continues to warn people to avoid contact with the debris due to the possible presence of hazardous chemicals.

On 27 March 2007, wreckage from a Russian spy satellite was spotted by Lan Chile (LAN Airlines) in an Airbus A340, which was travelling between Santiago, Chile, and Auckland, New Zealand, carrying 270 passengers.The pilot estimated the debris was within 8 km of the aircraft, and he reported hearing the sonic boom as it passed The aircraft was flying over the Pacific Ocean, which is considered one of the safest places in the world for a satellite to come down because of its large areas of uninhabited water.

In 1969, five sailors on a Japanese ship were injured by space debris, probably of Russian origin. In 1997 an Oklahoma woman named Lottie Williams was hit in the shoulder by a 10 cm × 13 cm (3.9 in × 5.1 in) piece of blackened, woven metallic material that was later confirmed to be part of the propellant tank of a Delta II rocket which had launched a U.S. Air Force satellite in 1996. She was not injured.


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