U.S. satellite scrap "hit" the Earth

The United States is to hit the Earth out of control satellite is expected to be the afternoon of September 23 fell to the ground the British media reported that the bus While similar in size with the satellite could fall anywhere on Earth, and mankind's only 20 seconds warning time. 

UK <<The Daily Telegraph>> September 22 reported that, at present, NASA (NASA) and U(http://www.f-paper.com/).S(News News http://www.f-paper.com/). Department of Defense experts are tracking Fengyun diameter of 10 meters, total weight about 6 tons of high-level meteorological research satellite, It is the speed of the Earth at 8 km, expected fragments of 800 km in diameter scattered in an area. 

'We know it will hit 57 degrees north latitude and 57 degrees south latitude to the middle of somewhere.' NASA scientist who studies garbage track Mark Martini said: 'Unfortunately, this covers the world's population live in absolute most of the region. 'alleged that the largest piece of debris about 136 kilograms, with a very large fridge.
Reported that, although the NASA spokesman has stressed that the satellite of the formation of human life and property risk is extremely small, but experts calculate that the formation of the debris hit on the person's probability of 1 / 3200 because of its falling fast, the human only 20 seconds of warning.
Currently, the U.S. Strategic Command Joint Space Operations Centre is expected to drop satellite time and place in the public notice to NASA and all federal security staff. NASA has warned people, if you see debris, do not touch, because they very sharp edges. 

Uncertain placement
Largest debris such as refrigerators
Space junk
Has reached the 'critical point'
Radiant space exploration history negative, is a dark history of space junk.
50 years ago, the former Soviet Union the first time in human history, space launch 'Sputnik' satellite, now, is running above the Earth's active-duty commercial, military and civilian satellites total of about 1000, but at the same time, human beings are left in space under a variety of junk, from cans to cigarette butts, grease gun to the spacecraft from debris from the satellite to its waste scattered parts, and now near-earth orbit the Earth, just like a high-tech garbage dump earlier this month, U.S. National Research Commission report that the number of space junk has reached 'critical point', the report said, under the U.S. Strategic Command space surveillance network in 2006 to 9949 orbital debris monitoring in 2011, this figure had risen to 16,094.
Although the majority of space junk will fall to the ground during the burning, but there are always some in the track year-round, 'wandering', making the circle more and more space junk, there is a greater chance of penetrating the spacecraft, astronauts security threats and data relay satellite .
Moreover, despite the retirement Satellite 'hit' the Earth is still rare, falling humans congregate very low probability, but if it continues unchecked, one day, space may become a real garbage dump, space junk 'accident' may be routine, may become reasonable alarmist synonym comprehensive Xinhua News Agency Xinhua 

Earth has a lot of rubbish near-Earth orbit debris
Ultra-rugged high-strength structural materials burn is not bad wrestling is not broken
Plunging to the ground satellite 'Hard' the most terrible
China Academy of Space Technology researcher Hao Pang told Xinhua News Agency reporter an exclusive interview that the satellite hit the Earth's trouble could have been avoided. If the fuel is sufficient, will not easily fall of the satellite guide to a higher orbit, or control it fell South Pacific spacecraft 'Cemetery', there would be no threat to the planet today.
'Upper Atmosphere Research Satellite' is a 1990s United States, 'Mission to Planet Earth program' to enable the first satellite, which aims to use a series of satellites to monitor Earth's environment. 'Upper Atmosphere Research Satellite,' in 2005 failed. After due runs out of fuel, the ground loses its control.
Threat is not the case the satellite hit the Earth European Space Agency announced on 12 September this year, its control of the number of retired observation satellite ERS2 have exhausted their fuel, the current accelerated fall in the future, can also cause problems.
Pang Zhihao said the country should be more scientific planning, so that each spacecraft can be 'obedient' to find a home.
Pang Hao said, the public need not worry too much about the satellite hit the Earth. Out of control satellite from the main threat on the ground in the body of the 'Hard.' Part of the key components of the satellite with high-strength titanium alloy material, and fuel tank design is generally very strong, these components in the satellite fell into the Earth's atmosphere is difficult to totally destroyed, the residual fragments will pound the ground in most cases, these pieces will fall into the ocean or unpopulated wilderness, etc. In addition, the United States and other countries now have the ability to fall to the ground in pieces forecast within a few hours before crash site, so the officers threatened areas time to evacuate or shelter.
Five ways to deal with the satellite hit the ground
A transfer to the retired spacecraft without prejudice to other spacecraft's orbit, such as high orbit far from Earth,
Second, the retired guide spacecraft plunged into the specified area,
Third, smaller spacecraft can be allowed to free fall, burned in the atmosphere,
Fourth, when the spacecraft to fall close to the orbit from the Earth, the use of anti-satellite weapons to blow to pieces. This method is usually used only for classified spacecraft, because if implemented properly, the spacecraft debris flying up , resulting in more space junk,
Fifth, use the space shuttle and other manned spacecraft to capture a large retired spacecraft back to the ground, but the U.S. space shuttle retired, the current method has been impossible to implement.
Currently, researchers are trying to use biodegradable materials spacecraft so that they can easily return to Earth, 'turned into smoke.'