China's decommissioned and allegedly out-of-control Tiangong 1 space station is expected to reenter Earth's atmosphere sometime this weekend. It poses little risk to people and property on the ground, as most of the 8.5-tonne bus vehicle is burned upon reentry into the city, although space agencies are not sure when and where that will happen  Below are some questions and answers about the station, its reentry and the past and future of China's ambitious space program
WHAT IS PRESENT AND HOW BIG IS THE DANGER?  The European Space Agency predicts that the station will re-enter the atmosphere between Saturday morning and Sunday afternoon ̵
China Space Agency's most recent estimate is a re-entry between Saturday and Wednesday.
Western space experts say they believe China has lost control of the station. Zhu Zongpeng, Chief Developer of the Space Laboratory in China, denied that Tiangong was out of control, but did not say what China would do to control the ship's re-entry.
Based on the orbit of Tiangong 1, it will come to Earth somewhere between latitudes 43 degrees North and 43 degrees South, or about anywhere across most of the United States, China, Africa, Southern Europe, Australia and South America. Out of reach are Russia, Canada and Northern Europe.
Due to its size, only about 10 percent of spacecraft will likely survive re-entry into the air, especially the heavier components such as the engines. The probability of anyone being hit by rubble on Earth is considered less than one to one trillion.
Ren Guoqiang, spokesman for the Chinese Ministry of Defense, told reporters on Thursday that Beijing has informed the United Nations and the international community about Tiangongs 1 -Interfacing over multiple channels
HOW TOGETHER IS MAN-MADE SPACE DEBRIS?
Debris from satellites, space launches, and the International Space Station enters the atmosphere every few months, but only one person American Lottie Williams, who struck in 1997 during a sport in an Oklahoma Park from a falling piece of a US Delta II missile hit, but was not injured.
America's most famous 77-ton Skylab crashed through the atmosphere in 1979, scattering debris near the city of Perth in southwestern Australia, which seized $ 400 for garbage.
The separation from the Columbia Space Shuttle in 2003 killed all seven astronauts and sent more than 80,000 debris on a large strip of the southern United States. No one on the ground was hurt.
In 2011, the NASA Atmospheric Research Satellite was considered a slight risk to the public when it came to Earth 20 years after its launch. Wreckage of the 6-ton satellite landed in the Pacific Ocean and caused no damage.
China's own space program was a source of concern after a missile killing an out-of-service Chinese satellite in 2007 and a potentially dangerous debris cloud.
WHAT IS TIANGONG 1 AND WHAT HAS IT BEEN USED?
Launched in 2011, Tiangong 1 was China's first space station to serve as an experimental platform for major projects such as Tiangong 2, launched in September 2016, and a future permanent Chinese space station.
The station, whose name translates as "Heavenly Palace", hosted two manned missions that included China's first female astronaut and served as a test platform to perfect docking and other operations. The last crew left in 2013 and contact was interrupted in 2016. Since then, they are increasingly distancing themselves from the earth while they are being monitored.
The station had two modules, one for their solar cells and motors, and one for an astronaut couple to live in and perform experiments. A third astronaut slept in the Shenzhou spacecraft docking at the station, which also included personal hygiene and food preparation facilities
HOW EXTENDS CHINA'S ROOM PROGRAM?
Since China occupied its first occupation The Mission in 2003 – to become only the third country after Russia and the US – has adopted increasingly ambitious projects, including a spacewalk and the landing of the Jade Rabbit Rover the moon.
China today operates the Tiangong 2 precursor space station facility, while the 20 ton core module of the base station is due to be launched this year. The completed 60-tonne station is expected to go into operation in 2022 and operate for at least a decade.
China was excluded from the 420-ton International Space Station, mainly due to US legislation that prohibits such cooperation and concerns about the Chinese military connections of the space program. China's space program is still very secretive and some experts have complained that a lack of information about Tiangong 1's design makes it difficult to predict what might happen after its reentry.
A mission to land another rover on Mars and bring back samples is scheduled to start in 2020. China also plans to become the first country to land a probe on the other side of the moon.