Hi, everybody: Please chill out.
While some overblown headlines may lead you to believe that China’s space station module — which played host to Chinese astronauts in the past — is on an imminent, possibly dangerous crash course with Earth, that’s not the full story.
It’s true that eventually China’s Tiangong-1 — which translates to “heavenly palace” in English — will eventually come back through Earth’s atmosphere, but that breakup isn’t necessarily happening in the next few weeks, and even if it were, it shouldn’t necessarily be a cause for serious concern.
“It’s way down on my list of things to panic about,” astrophysicist and spaceflight enthusiast Jonathan McDowell told Mashable in an interview.
When and where?
The likelihood that the spacecraft, which China designed as a proving ground for future crewed space missions, will make its fiery re-entry above a large population center is quite low.
Although some bits of debris might make it back to Earth intact, the chance that it could cause damage or hurt someone is about 1 in 10,000, McDowell said.
Like many other spacecraft currently in orbit right now, Tiangong-1 is expected to de-orbit eventually, so when — and where — will that be?
McDowell has been keeping a close eye on Tiangong-1’s orbit for some time and notes that Chinese mission controllers have boosted the spacecraft’s orbit with engine burns many times since its launch in 2011.
Just judging by the spacecraft’s orbit — which brings it about 211 miles, or 340 kilometers, above Earth, the Chinese craft isn’t due to re-enter Earth’s atmosphere until 2017 at the earliest, McDowell said.
According to McDowell’s calculations, Tiangong-1 isn’t due for its next reboost until later this year or early next. That means that right now it may appear to be descending on a crash course, but it’s current trajectory is likely to be misleading.
Instead, whether it reboosts or not will provide a better indication of what kind of control mission managers have over it.
An uncontrolled re-entry?
There are, however, reasons to think that all is not well with Tiangong-1.
A report from an amateur astronomer interviewed by Space.com claims that the Chinese space module is rolling in its orbit, as observed through changes in its brightness in the night sky — meaning that it could be flipping around uncontrolled.
China’s state-run media reported earlier this year that Tiangong-1 had “terminated its data service,” meaning that it may no longer be sending information back to the ground. That may also indicate that mission controllers aren’t able to communicate with the module.
However, it’s unclear what exactly is going on, since China tends to keep their space plans rather hush-hush.
It’s way down on my list of things to panic about
For his part, McDowell thinks it’s possible the spacecraft could be tumbling, or it might just be in a controlled spin, hibernating in orbit until it comes back through the atmosphere.
Ideally, Chinese officials will control Tiangong-1’s de-orbit using thrusters that will force the spacecraft down over a specific part of the world, probably in the Pacific Ocean far from civilization. They would also alert the proper authorities before the craft burns up in the atmosphere.
That kind of controlled re-entry would follow guidelines put in place by the United Nations.
But even if Tiangong-1 makes an uncontrolled re-entry, it won’t be the first time an object around this size (about 8 metric tons and 34 feet long) has burned up in the atmosphere.
Something of this size re-enters the atmosphere every couple of years, McDowell said, adding that “we have two ton things retiring all the time.”
McDowell also thinks that it’s possible Chinese officials will keep Tiangong-1 in orbit until Tiangong-2 makes it to space during a planned launch later this year.
The first module may be kept in orbit until controllers on the ground know that Tiangong-2 is safely above Earth and they no longer need the first module as a backup plan.
Operations on Tiangong-1 were specifically designed to help pave the way for China to eventually build a full space station in orbit around Earth sometime during the 2020s.
If you want to investigate for yourself, Tiangong-1 can be spotted from the ground if you know where to look. You can use tools like N2YO.com to figure out when to look up and maybe spot the speeding spacecraft.