BEIJING- An uncontrolled Chinese space station weighing at least seventonnes is set to break up as it hurtles to Earth on or around April 1, theEuropean Space Agency has forecast.
“It will mostly burn up due to the extreme heat generated by its high-speedpassage through the atmosphere,” it said in a statement.
Some debris from the Tiangong-1 — or “Heavenly Palace” — spacelab willlikely fall into the ocean or somewhere on land, but the chances of humaninjury are vanishingly small, said Stijn Lemmens, an ESA space debrisexpert based in Darmstadt, Germany.
“Over the past 60 years of space flight, we are nearing the mark of 6,000uncontrolled reentries of large objects, mostly satellites and upper(rocket) stages,” he told AFP.
More than 90 percent of those bits of high-tech space junk weighed 100kilos (220 pounds) or more.
“Only one event actually produced a fragment which hit a person, and it didnot result in injury.”
Lemmens calculated the odds of being struck by space debris at one in 1.2trillion — 10 million times less likely than getting hit by lightning.
The China Manned Space programme, which put Tiangong-1 into orbit inSeptember 2011, has been mostly mum on the fate of China’s first spacestation, designed to test technologies related to docking in orbit.
Daily updates on its official website have tracked its gradual descent –average altitude as of Tuesday was 207.7 kilometres (129 miles) — but notmuch else.
On Monday, China’s state-run news agency Xinhua cited the agency as sayingthe spacelab “should be fully burnt as it reenters the Earth’s atmosphere.”
During its operational lifetime, Tiangong took part in two crewed missions,and an unmanned one.
As with all large satellites and spacecraft, the Chinese spacelab had beenslated for a “controlled reentry” that would have seen it fall somewhere inthe Pacific Ocean, far from human habitation.
In March 2016, however, the space station ceased functioning.
– ‘Design for demise’ –
With ground teams no longer able to ignite its engines, Tiangong is”expected to make an ‘uncontrolled reentry’,” the ESA said.
“It can be surmised that Tiangong-1 will break up during its atmosphericreentry and that some parts will survive the process and reach the surfaceof Earth.”
Debris has become a major headache for space agencies and private companieslobbing satellites and other modules into Earth orbit.
The problem is not what comes back down, but what stays in space.
More than 5,000 rockets launched since 1957 have hoisted some 7,500satellites into orbit, with more than 4,300 of them still in place.
The US Space Surveillance Network tracks some 23,000 debris objectstravelling at speeds of up to 28,000 kilometres per hour (17,500 miles perhour).
Statistical models estimate that there are nearly 30,000 objects of atleast 10 centimetres across, and 20 times that number measuring between oneand 10 cm in diameter.
“These form a real collision risk for spacecraft and manned space-flightactivity,” said Lemmens.
“What we really fear is the so-called ‘Kessler Syndrome’, whereby objectscollide in an exponential cascade, with one collision causing thousands offragments that in turn start colliding with others.”
Not much can be done to reduce the volume of orbiting space junk, much ofwhich will eventually drift into Earth’s atmosphere and burn up.
To avoid further clutter, programmed reentry is crucial, said Lemmens. Allnations capable of launching a spacecraft have signed a treaty making themliable for damages caused, in space or on Earth, he noted.
Future spacecraft will also be ‘designed for demise’ upon reentry.
A new generation of fuel tanks, for example, will replace ones currentlymade with titanium, which can withstand very high temperatures.
Tiangong-1 weighed 8.5 tonnes on take off, but with fuel consumption hasprobably shed at least one tonne. APP/AFP