Is Tiangong-1 Going To Fall On My Head?

Watch out: China’s ill-fated prototype station will crash sometime next year, but don’t worry—it will likely fall in an unpopulated area.

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AsianScientist (Oct. 27, 2016) – The Chinese prototype space station Tiangong-1 (‘Heavenly Palace’), which is hurtling uncontrollably around the Earth, has apparently received a diagnosis on its point of failure. It has lost power due to a malfunctioning battery charger. Presumably, they did not purchase their batteries and chargers from Samsung.

It’s interesting to read the comments on social media regarding the rogue satellite. “Boo! Made in China!” and other such comments indicate global opinion of Chinese manufactured goods. But of course, the US never made a faulty space station which fell uncontrollably to Earth, did they? *cough* Skylab *cough*

Let’s be fair to China. Tiangong-1 was designed with a two-year operational lifespan, and it exceeded that lifespan by nine months. Nine months may not sound like a lot in Earth time, but in space, that’s a fairly wide margin. Mission success.

A lot has been learned from the experience. Tiangong-1 was an engineering testbed designed to perfect orbital rendezvous techniques, and they certainly achieved that goal having docked three spacecraft with the station. One of those spacecraft, Shenzhou 9, carried China’s first female taikonauts. Knowledge gained from this project has also been fundamental to the design and operation of the recently-launched Tiangong-2, and the future Chinese modular space station.

The Chinese National Space Administration (CNSA) has had Tiangong-1 operating in ‘sleep mode’ since 2013, so that the agency could better monitor the lifespan of key components. I think it’s fair to say that they now have a reliability figure for their battery chargers.


Down to Earth

In September 2016, a spokeswoman for CNSA announced that yes indeed, the agency had lost control and telemetry of Tiangong-1, that its orbit is decaying at a rate of around 100 meters per day, and that it should crash (or hopefully splash) down to Earth sometime in late 2017. And just like Skylab, it is impossible to predict exactly where or when Tiangong-1 will hit Earth at this moment in time.

There are too many factors at work to be able to accurately predict such a thing. Effects such as differential drag will act on the spacecraft changing its velocity over time, so even an educated guess is out of the question. Predicting where the space station will land in 2017 is akin to me predicting where my paper aeroplane will land if I throw it out of my eighth storey window next Thursday. It would be hard enough to predict if I threw it out at this very moment in time, let alone having to account for the effect of next week’s unknown weather situation on the paper dart.

There are too many unforeseen and unpredictable factors at play. Forecasting exact orbital decay is exactly the same. Really, the only things that we can be sure of is that the station will touch down in late 2017, and that it will fall somewhere in between 42.7 degrees north and 42.7 degrees south of the equator.

But not to worry: CNSA has assured everyone that it is likely to fall in an unpopulated area, which statistically is probably correct. There is a lot of desert and ocean in between those two latitudes, so it is unlikely that it will fall on my particular head. And Singapore, where I’m based, is a very small target, so we are pretty safe here on the Red Dot.

But then, NASA said the same thing about Skylab, and as the people of Esperance in Western Australia can confirm, burning space wreckage does occasionally rain down from the sky. Hopefully, CNSA will pay the litter fine if Tiangong 1 does touchdown in a populated region—unlike NASA, who still owes the Esperance town council AU$400 (~US$381).


This article is from a monthly column called Final Frontiers. Click here to see the other articles in this series.

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Copyright: Asian Scientist Magazine; Photo: Shutterstock.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.

Phillip Keane has a bachelor degree in aerospace engineering from Coventry University, UK, and an MSc in Space Studies from International Space University in France. He loves all things space and science fiction.

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