Debris from space enters the atmosphere every few months, but only one person is known to have been hit by any of it: American woman Lottie Williams, who was struck but not injured by a falling piece of a U.S. Delta II rocket while exercising in an Oklahoma park in 1997.

BEIJING — China’s defunct and reportedly out-of-control Tiangong 1 space station is expected to re-enter Earth’s atmosphere sometime this weekend. It poses only a slight risk to people and property on the ground, since most of the bus-size, 8.5-ton vehicle is expected to burn up on re-entry, although space agencies don’t know exactly when or where that will happen.

Below are some questions and answers about the station, its re-entry and the past and future of China’s ambitious space program.

What will happen and how great is the danger?

The European Space Agency predicts the station will re-enter the atmosphere between Saturday morning and Sunday afternoon — an estimate it calls “highly variable,” likely because the ever-changing shape of the upper atmosphere affects the speed of objects falling into it.

The Chinese space agency’s latest estimate puts re-entry between Saturday and Wednesday.

Western space experts say they believe China has lost control of the station. China’s chief space laboratory designer Zhu Zongpeng has denied Tiangong was out of control, but hasn’t provided specifics on what, if anything, China is doing to guide the craft’s re-entry.

Based on Tiangong 1’s orbit, it will come to Earth somewhere between latitudes of 43 degrees north and 43 degrees south, or roughly somewhere over most of the United States, China, Africa, southern Europe, Australia and South America. Out of range are Russia, Canada and northern Europe.

Based on its size, only about 10 percent of the spacecraft will likely survive being burned up on re-entry, mainly its heavier components such as its engines. The chances of anyone person on Earth being hit by debris is considered less than one in a trillion.

Ren Guoqiang, China’s defense ministry spokesman, told reporters Thursday that Beijing has been briefing the United Nations and the international community about Tiangong 1’s re-entry through multiple channels.

Debris from satellites, space launches and the International Space Station enters the atmosphere every few months, but only one person is known to have been hit by any of it: American woman Lottie Williams, who was struck but not injured by a falling piece of a U.S. Delta II rocket while exercising in an Oklahoma park in 1997.

Most famously, America’s 77-ton Skylab crashed through the atmosphere in 1979, spreading pieces of wreckage near the southwestern Australia city of Perth, which fined the U.S. $400 for littering.

The breakup on re-entry of the Columbia space shuttle in 2003 killed all seven astronauts and sent more than 80,000 pieces of debris raining down on a large swath of the Southern United States. No one on the ground was injured.

In 2011, NASA’s Upper Atmosphere Research Satellite was considered to pose a slight risk to the public when it came down to Earth 20 years after its launching. Debris from the six-ton satellite ended up falling into the Pacific Ocean, causing no damage.

China’s own space program raised major concerns after it used a missile to destroy an out-of-service Chinese satellite in 2007, creating a large and potentially dangerous cloud of debris.

What is tiangong 1 and what was it used for?

Launched in 2011, Tiangong 1 was China’s first space station, serving as an experimental platform for bigger projects such as the Tiangong 2 launched in September 2016 and a future permanent Chinese space station.

The station, whose name translates as “Heavenly Palace,” played host to two crewed missions that included China’s first female astronauts and served as a test platform for perfecting docking procedures and other operations. Its last crew departed in 2013 and contact with it was cut in 2016. Since then it has been orbiting gradually closer and closer to Earth on its own while being monitored.

The station had two modules, one for its solar panels and engines, and one for a pair of astronauts to live in and conduct experiments. A third astronaut slept in the Shenzhou spaceships that docked with the station, which also contained facilities for personal hygiene and food preparation.

Since China conducted its first crewed mission in 2003 — becoming only the third country after Russia and the U.S. to do so — it has taken on increasingly ambitious projects, including staging a spacewalk and landing its Jade Rabbit rover on the moon.

China now operates the Tiangong 2 precursor space station facility, while the permanent station’s 20-ton core module is due to be launched this year. The completed 60-ton station is set to come into full service in 2022 and operate for at least a decade.

China was excluded from the 420-ton International Space Station mainly due to U.S. legislation barring such cooperation and concerns over the Chinese space program’s strong military connections. China’s space program remains highly secretive and some experts have complained that a lack of information about Tiangong 1’s design has made it harder to predict what might happen upon its re-entry.

A mission to land another rover on Mars and bring back samples is set to launch in 2020. China also plans to become the first country to soft-land a probe on the far side of the moon.</s>With China's Tiangong-1 space station (translated as "Heavenly Palace") full of highly toxic chemicals such as hydrazine, set to crash into the earth at a still unknown location some time today, Michigan isn't taking any chances.

As a reminder, several weeks ago Aerospace.org predicted that while the list of possible crash sites includes locations in Northern China, South America, Southern Africa, Northern Spain and the United States, lower Michigan in particular is among the regions with the highest probability of a direct hit.

Fast forward to today when in advance of Tiangong's atmospheric reentry, sometime between now and April 2, Michigan Gov. Rick Snyder has activated the state's Emergency Operations Center today to monitor its travels.

According to the Detroit Free Press, and as noted previously, pieces of the 8.5 ton space station have the potential to land in the southern Lower Peninsula of Michigan, according to the Aerospace Corporation. Still , while the possibility that space debris could land in Michigan looms, the odds of it actually happening are miniscule.

"When considering the worst-case location ... the probability that a specific person (i.e., you) will be struck by Tiangong-1 debris is about 1 million times smaller than the odds of winning the Powerball jackpot," according to Aerospace, a government contractor that provides research, development, and advisory services to national-security space programs.

In any event, Michigan's Emergency Operations Center urges anyone who suspects they have encountered debris from the space station to call 911 and stay at least 150 feet away from it.

In a follow up article we will present readers with several options on how to track the space station's trajectory in real time.</s>The Chinese space lab Tiangong-1 is expected to fall back to Earth within the next 24 hours, putting an end to the nearly 19,000-pound, out-of-control space craft.

Tiangong-1, or “Heavenly Palace,” will re-enter the Earth’s atmosphere at some point late Sunday evening or early Monday morning, according to the European Space Agency’s Space Debris Office.

The estimates were made on Coordinated Universal Time, which is four hours ahead of Eastern Time.

The Space Agency notes the spacecraft could hit the Earth anywhere within a large band of 43 degrees north and 43 degrees south of the equator. That area includes the majority of the United States, Mexico, South America, Africa, India, Australia and a host of other countries. The chance of someone getting hit by the spacecraft is very low, as TIME has previously reported. According to the Aerospace Corporation, the odds of someone getting hit by a falling space object like this one is less than 1 in 1 trillion, and debris from the spacecraft will most likely fall into the ocean.

People can expect to see what will look like “a shower of meteors,” according to the China Manned Space Engineering Office.

The “Heavenly Palace” space station was China’s first as the country bulked up its space program. The spacecraft was launched into space in September 2011, and has been the site of a two-man mission and a three-man mission. The latter mission included China’s first female astronaut, Liu Yang.

Tiangong-1 lost connection with Earth back in 2016, however, making the spacecraft’s reentry to the Earth’s atmosphere an out-of-control fall. The unsuccessful orbit for the spacecraft did not slow down China’s space program, however. The country launched the larger Tiangong-2 in September 2016, and that spacecraft is now in orbit.</s>BERLIN (AP) — China's defunct Tiangong 1 space station hurtled toward Earth on Sunday and was expected to re-enter the atmosphere within hours.

Most of the craft should burn up on re-entry, so scientists said falling debris poses only a slight risk to people on the ground.

The European Space Agency forecast that the station, whose name translates as "Heavenly Palace," will re-enter sometime between Sunday night and early Monday GMT. The Chinese space agency said it should happen during the course of Monday Beijing time.

The Aerospace Corp. predicted Tiangong 1's re-entry would take place within 2 hours of either side of 0018 GMT Monday (8:18 p.m. Sunday EDT.)

Based on the space station's orbit, it will come back to Earth somewhere 43 degrees north and 43 degrees south, a range covering most of the United States, China, Africa, southern Europe, Australia and South America. Out of range are Russia, Canada and northern Europe.

Only about 10 percent of the bus-sized, 8.5-ton spacecraft will likely survive being burned up on re-entry, mainly its heavier components such as its engines. The chances of any one person being hit by debris are considered less than one in a trillion.

Launched in 2011, Tiangong 1 was China's first space station, serving as an experimental platform for bigger projects, such as the Tiangong 2 launched in September 2016 and a future permanent Chinese space station.

The station played host to two crewed missions and served as a test platform for perfecting docking procedures and other operations. Its last crew departed in 2013 and contact with it was cut in 2016.

Since then, it has orbited gradually closer and closer to Earth on its own while being monitored.

Many Western space experts think China has lost control of the station. China's chief space laboratory designer, Zhu Zongpeng, has denied Tiangong was out of control, but hasn't provided specifics on what, if anything, China was doing to guide the craft's return to Earth.</s>China's defunct Tiangong 1 space station hurtled toward Earth on Sunday and was expected to re-enter the atmosphere within hours.

Most of the craft should burn up on re-entry, so scientists said it poses only a slight risk to people on the ground.

The European Space Agency forecast that the station, whose name translates as "Heavenly Palace," will re-enter sometime between Sunday night and early Monday GMT. The Chinese space agency said it should happen during the course of Monday Beijing time.

The Aerospace Corp. predicted Tiangong 1's re-entry would take place within 2 ½ hours of either side of 0010 GMT Monday (8.10 p.m. Sunday EDT.)

Based on the space station's orbit, it will come back to Earth somewhere 43 degrees north and 43 degrees south, a range covering most of the United States, China, Africa, southern Europe, Australia and South America. Out of range are Russia, Canada and northern Europe.

Only about 10 percent of the bus-sized, 8.5-ton spacecraft will likely survive being burned up on re-entry, mainly its heavier components such as its engines. The chances of any one person being hit by debris are considered less than one in a trillion.

Launched in 2011, Tiangong 1 was China's first space station, serving as an experimental platform for bigger projects, such as the Tiangong 2 launched in September 2016 and a future permanent Chinese space station.

The station played host to two crewed missions and served as a test platform for perfecting docking procedures and other operations. Its last crew departed in 2013 and contact with it was cut in 2016.

Since then it has been orbiting gradually closer and closer to Earth on its own while being monitored.

Western space experts say they believe China has lost control of the station. China's chief space laboratory designer Zhu Zongpeng has denied Tiangong was out of control, but hasn't provided specifics on what, if anything, China is doing to guide the craft's re-entry.</s>
• China lost control of its first space station, Tiangong-1, or "Heavenly Palace" in March of 2016.
• The spacecraft is expected to burn up in Earth's atmosphere on the evening of April 1.
• As of Sunday afternoon EST, this means Tiangong-1 is about 8 hours away from crashing, give or take two and a half hours.
• Pieces of the bus-size vessel should be durable enough to reach our planet's surface.
• Any surviving pieces of Tiangong-1 will most likely land in the ocean.

China's first space station, called Tiangong-1 or "Heavenly Palace," will soon break up over Earth into a fiery rain of space — and the predictions for when it's coming down are getting more exact.

The Aerospace Corp., a nonprofit spaceflight research company, has released its newest prediction about the derelict spacecraft's doom: Tiangong-1 should reenter Earth's atmosphere on April 1 at 8:10 p.m. ET, give or take 2.5 hours. This is similar to the latest prediction by the European Space Agency (ESA), which expects the space station fall sometime in the night of April 1 or early morning of April 2.

This means the dead spacecraft should come crashing down in about 8 hours, providing fireworks high in the sky at the start of April.

When it does, extreme heat and pressure caused by plowing through the air at more than 15,000 mph will destroy the roughly 9.4-ton vessel.

Not everything may vanish, though.

There's a good chance that gear and hardware left onboard could survive intact all the way to the ground, according to Bill Ailor, an aerospace engineer who specializes in atmospheric reentry. That durability is thanks to Tiangong-1's onion-like layers of protective material.

"The thing about a space station is that it's typically got things on the inside," Ailor, who works for The Aerospace Corp., previously told Business Insider. "So basically, the heating will just strip these various layers off.

"If you've got enough layers, a lot of the energy is gone before a particular object falls out, it doesn't get hot, and it lands on the ground."

For example, he said, after NASA's Columbia space shuttle broke up over the US in 2003, investigators recovered a working flight computer. (The artifact that ultimately helped explain how the deadly incident happened.)

Launched in September 2011, Tiangong-1 is a two-room space station that two crews of taikonauts, or Chinese astronauts, visited.

It's 34 feet long and has a volume of 15 cubic meters, or about 1/60th of the volume of the International Space Station, which is about the length of a football field.

Though China superseded Tiangong-1 in 2016 with Tiangong-2, space experts hailed the first space station as a major achievement for the nation, since it helped pioneer a permanent Chinese presence in orbit.

"It conducted six successive rendezvous and dockings with spacecraft Shenzhou-8, Shenzhou-9, and Shenzhou-10 and completed all assigned missions, making important contributions to China's manned space exploration activities," said a memo that China submitted in May 2017 to the United Nations Committee on the Peaceful Uses of Outer Space.

In the memo, China said it lost contact with the spacecraft on March 16, 2016, after it "fully fulfilled its historic mission."

By May 2017, Tiangong-1 was coasting about 218 miles above Earth and dropping by about 525 feet a day, the memo said. Its altitude has since plummeted to an altitude of about 92 miles, according to the Aerospace Corporation's latest data.

"For any vehicle like this, the thing that brings them down is atmospheric drag," Ailor said. "Why there's a lot of uncertainty in the predictions is that it depends on what the sun's doing, to a large measure."

The sun can unleash solar storms and solar flares — bursts of X-rays and ultraviolet light — that heat Earth's outer atmosphere, causing the air to expand and rise. That forces low-flying objects like Tiangong-1 to plow through denser gases.

"This puts just a little bit of a higher force on these objects that causes them to come down," Ailor said.

An analysis of the combined effects of solar activity and Tiangong-1's orbital speed, direction, and altitude, as well as other factors, helps the Aerospace Corporation provide its latest by-the-minute deorbit estimates.

The European Space Agency (ESA) reported on Friday that calm space weather shifted the window for the expected landing later in the day on April 1, though things are still highly variable.

Tiangong-1 is likely to crash over the ocean, as water covers about 71% of Earth's surface.

But there's a decent chance some pieces may strike land as it breaks up over a long and thin oval footprint.

"The whole footprint length for something like this could be 1,000 miles or so," Ailor said, with heavier pieces at the front and lighter debris toward the back.

If anyone is lucky enough to witness Tiangong-1's atmospheric breakup from an airplane, it may look similar to the destruction of the European Space Agency's 14-ton Automated Transfer Vehicle in 2015.

The ATV was an expendable spacecraft that used to resupply the ISS. Once astronauts and cosmonauts unloaded its supplies, it was filled with garbage and sent careening back to Earth.

When asked for comment on Tiangong-1's threat to ongoing NASA missions, the space agency told Business Insider it "actually doesn't track any debris."

But Ailor said pieces of China's space station are "really unlikely" to hit anyone or anything on Earth. Re-entry will occur between latitudes of 43ºN and 43ºS, shown in the map below.

According to The Aerospace Corp.'s website, the probability of being hit "is about 1 million times smaller than the odds of winning the Powerball jackpot."

"It's not impossible, but since the beginning of the space age ... a woman who was brushed on the shoulder in Oklahoma is the only one we're aware of who's been touched by a piece of space debris," he said.

Should a hunk of titanium, a computer, or another piece smash through a roof or windshield, however, international space law covers compensation for victims.

"It's China's responsibility if someone gets hurt or property gets damaged by this," NASA's representative said.

This story has been updated with new information. It was originally published on January 2, 2018.

More on the crash of Tiangong-1:
• A Chinese space station is about to crash to Earth — here's what it was doing
• These may be the last photos of the Chinese space station before it falls to Earth
• A Chinese space station is hurtling toward Earth — here's how to track the crash as it happens
• China's out-of-control space station may release a toxic chemical when it crashes
• More than 14,000 hunks of dangerous space junk are hurtling around Earth — here's who put it all up there
• China's out-of-control space station will soon fall to a fiery doom — and no one is sure where its pieces will crash</s>A defunct Chinese space laboratory is set to become a “splendid” meteor shower as it re-enters Earth’s atmosphere on Monday, Chinese authorities maintain.

Hitting speeds of over 26,000km an hour before disintegrating, the Tiangong-1 is expected to make an uncontrolled earthbound plunge on Monday Beijing time, China’s Manned Space Agency said on Sunday – an estimate roughly in line with European Space Agency projections.

The Manned Space Agency did not specify a time when it expects the craft to enter the atmosphere.

South Korea’s National Space Situational Awareness Organisation said on Sunday the 10.4-metre-long (34-foot) station is expected to re-enter the atmosphere some time between 5.12am and 1.12pm Seoul time on Monday (8.12pm on Sunday and 4.12am on Monday GMT).

The debris from the abandoned eight-tonne craft could land anywhere between the latitudes of 43 degrees north and 43 degrees south – from New Zealand to the American midwest, the ESA said.

Many experts believe much of the station will burn up during re-entry. Beijing said on Friday that it is unlikely any large pieces will reach the ground. 



There is “no need for people to worry”, the China Manned Space Engineering Office said on its WeChat social media account.

Such falling spacecraft do “not crash into the Earth fiercely like in sci-fi movies, but turn into a splendid [meteor shower] and move across the beautiful starry sky as they race towards the Earth”, it said.

Tiangong-1, or “Heavenly Palace”, was launched in 2011 to carry out docking and orbit experiments. It was originally planned to be decommissioned in 2013 but its mission was repeatedly extended.

China had said its re-entry would occur in late 2017 but that process was delayed, leading some experts to suggest the space laboratory is out of control. Chinese media has downplayed these comments, saying the reports are an invention of the foreign media.

On Chinese social media, however, commenters criticised the government’s reluctance to own up to the situation.

“Can you or can’t you report that you’ve lost control of the situation?” one commenter wrote on the Twitter-like Weibo. “It’s not unusual that something this complicated would have a mishap.”</s>A Chinese space lab could plummet back to Earth in the next 24 hours, authorities say, in a fiery end to one of the country's highest profile space projects.

The 40-foot long Tiangong-1 or "Heavenly Palace," is expected to re-enter the Earth's atmosphere between Sunday night and Monday morning US eastern time, according to the latest updates from the European Space Agency and the China Manned Space Engineering Office. Earlier estimates put the date as late as April 4.

Scientists have emphasized the danger of being hit by falling debris is tiny, as low as one in 1 trillion, as the structure is likely to burn up in the atmosphere during reentry.

"There is no need for people to worry about its re-entry into the atmosphere," an article by the China Manned Space Engineering Office published on state media said.

"It won't crash to the Earth fiercely, as in sci-fi movie scenarios, but will look more like a shower of meteors."

The Tiangong-1 was launched in September 2011 as a prototype for China's ultimate space goal: a permanent space station which is expected to launch around 2022.

But the Chinese government told the United Nations in May 2017 their space lab had "ceased functioning" in March 2016, without saying exactly why.

As of Thursday, the space lab is orbiting the Earth at a height of 196.4 kilometers (122 miles).

Although the incident has been embarrassing for the China's space program, it hasn't delayed its progress. In September 2016 the Tiangong-2 space lab was successfully launched and put into orbit.

Witnesses may see 'series of fireballs'

Markus Dolensky, technical director of the International Center for Radio Astronomy Research in Australia, said witnesses to the Tiangong-1 descent should see "series of fireballs" streaking across the sky -- provided there were no clouds.

"It is now nearing its fiery demise as it gradually gets slowed down by the fringes of the Earth's upper atmosphere," he said.

While it is not uncommon for debris such as satellites or spent rocket stages to fall to Earth, large vessels capable of supporting human life are rarer.

NASA's first space station, Skylab, fell to Earth in an out-of-control reentry in 1979, burning up harmlessly in the process.

The last space outpost to drop was Russia's 135-ton Mir station in 2001, which made a controlled landing with most parts breaking up in the atmosphere.

The re-entry latitude of the Tiangong-1 is expected to be within 43 degrees north and 43 degrees south of the equator, a huge swath of the earth which stretches from New York to Cape Town. Scientists say it's not possible to be more specific about exactly where it will come down.

"Some parts of the upper atmosphere are thicker than others meaning the craft slows unpredictably and since it travels around the Earth in just 90 minutes even an uncertainty of a two minutes means the craft could fall anywhere along a 1,000 kilometer track," Alan Duffy, a research fellow in the Center for Astrophysics and Supercomputing at Swinburne University of Technology in Australia, said.</s>An out-of-control Chinese space station is set to crash to Earth in the early hours of Monday morning - but no one knows exactly where.

The defunct Tiangong-1 ("Heavenly Palace-1") spacecraft is expected to fall to Earth around 2.07am BST, plus or minus two hours.

Much of the 34-ft long, 8.5-tonne module is expected to burn up when it re-enters the Earth's atmosphere, with experts predicting any surviving components such as tanks will land in the sea.

But there's a slight risk fragments of the space laboratory could hit a populated area when it hurtles towards Earth in a wide range that includes southern Europe (not including the UK), the US, most of Asia and South America, Africa, Australia and part of New Zealand.

More than 5bn people live within the re-entry zone - between 43 degrees north and south of the equator - but most of that area is ocean.

China has lost communication with the spacecraft and is unable to control its descent, but has said it's unlikely that any large pieces will reach the ground.

The station was launched in 2011 to carry out docking and orbit experiments under China's ambitious space programme, and was visited by six astronauts.

It was initially supposed to be taken out of service in 2013, but its mission was repeatedly extended.

China's Manned Space Agency had announced the Tiangong-1 would crash to Earth in late 2017, but that process was delayed, leading to speculation that the space laboratory was out of control.

The spacecraft is being tracked by space agencies around the world as it plummets towards Earth.

Richard Crowther, the UK Space Agency's chief engineer, told the BBC: "Given Tiangong-1 has a larger mass and is more robust, as it is pressurised, than many other space objects that return uncontrolled to Earth from space, it is the subject of a number of radar tracking campaigns.

"The majority of the module can be expected to burn up during re-entry heating, with the greatest probability being that any surviving fragments will fall into the sea."</s>Only around 10 percent of the 8.5-ton spacecraft is likely to survive. This will most likely be its heavier components such as its engines. Astronomer Jonathan McDowell of the Harvard-Smithsonian Centre for Astrophysics said on Twitter: “Remember: 1) this thing will reenter spectacularly but it will (almost super certainly) not hurt anyone. “2) We may not know that it's come down until an hour or so after it actually has done.” The chances of any one person being hit by debris are considered less than one in a trillion by the Aerospace Corporation.

Most of the space station will dissipate in the air and a small amount of debris will fall relatively slowly before landing across hundreds of square miles, most likely in the ocean. The ocean covers more than 70 per cent of the Earth's surface. The European Space Agency said that nearly 6,000 uncontrolled re-entries of large objects have occurred over the past 60 years and none of them have caused any harm. The largest object to renter Earth to date was Russia's MIR space lab in 2001 which weighed 120 tonnes. Meterologist Bryan Bennett said: “When it reaches 65 miles above the Earth it will no longer be able to orbit and will begin its rapid re-entry.

“Atmospheric breakup will begin when it reaches 50 miles above the Earth and undergo a fiery reentry until about 30 miles.” Andrew Abraham, a senior member of Aerospace's technical staff, said: "We know that Tiangong-1 is tumbling, or at least it was when Germany took a radar update, so the question is it still tumbling, and is the tumbling getting faster or slower.”

The Chinese tabloid Global Times said on Monday worldwide media hype about the re-entry reflected overseas "envy" of China's space industry. It said: ”It's normal for spacecraft to re-enter the atmosphere, yet Tiangong-1 received so much attention partly because some Western countries are trying to hype and sling mud at China's fast-growing aerospace industry.” Beijing said on Friday it was unlikely any large pieces would reach the ground and would therefore be unlikely to cause any damage. China had said its re-entry would occur in late 2017 but that process was delayed, leading some experts to suggest the space laboratory is out of control. The space station, also known as "Heavenly Palace 1”, was launched in 2011 to carry out docking and orbit experiments as part of China's ambitious space programme, which aims to place a permanent station in orbit by 2023.
Updated analysis by the European Space Agency and Aerospace Corporation suggests that the derelict Chinese space station Tiangong-1 will crash on tomorrow evening or the day thereafter in the morning. Although the prediction remains highly uncertain, the station may impact around Africa.