Commentary: China's "Heavenly Palace" space station is headed back to Earth, and it almost certainly won't hit you. Still, it's human nature to worry, at least a little.
Here are the facts: China's 9-ton Tiangong-1 space station appears to be out of control and heading for a collision with Earth sometime this weekend. The bus-size spacecraft is massive enough that it might not totally burn up in the atmosphere, leaving some pieces to hit our fair planet.
So an obvious question for most of us on Earth is: Should I be freaked out about the possibility of getting clobbered by a falling space station?
Probability-wise, the answer is pretty clear. You and everyone you know will almost certainly survive the fall of the Heavenly Palace (the Chinese translation of Tiangong).
Since humans started sending big stuff to space that carried with it the risk of falling back down on top of us, only one person has ever been struck by such debris -- a small piece hit Lottie Williams' shoulder as she walked through an Oklahoma park in 1997, and she was fine.
Furthermore, while debris from Tiangong-1 could theoretically reach the surface of the Earth anywhere between 43 degrees north and south of the equator, most of that area is covered by ocean. Take the remaining area that's land and only a small percent (3 percent on average) falls in urban areas.
"The personal probability of being hit by a piece of debris from the Tiangong-1 is actually 10 million times smaller than the yearly chance of being hit by lightning," the European Space Agency explains in its FAQ on the reentry.
So, rationally, there's nothing to worry about. You're going to put yourself in far more danger next time you climb into any kind of motor vehicle, take a drag of a cigarette or eat a hamburger (which is more risky both because of its high fat content and the potential for choking on it).
But, emotionally, it's OK to be a little bothered by the fact that a huge hunk of metal is falling from the heavens and there's no way to do anything about it. It's not really even possible to predict where or when it will land, meaning no preparations or preventive measures can be taken.
This complete lack of control over a potentially lethal threat is, in itself, a scary notion to humans, even if we know rationally that it's unlikely to affect us individually.
"The more serious the threat and the more emotional the topic (such as radioactivity), the less reassuring a reduction in risk seems to us," author, philosopher and author Rolf Dobelli writes in "The Art of Thinking Clearly." "Two researchers at the University of Chicago have shown that people are equally afraid of a 99 percent chance as they are of a 1 percent chance of contamination by toxic chemicals. An irrational response, but a common one."
Another study looked at how fearful people in Israel were the day before the partially out-of-control Skylab space station finally crashed to the ground (mostly in rural Australia) in 1979. It found many of the people surveyed overrated the risk posed by that falling space junk and concluded the errors in judgment "may be due to inability to handle rationally probabilistic types of information, and ... fear of science and technology (which may be stronger among individuals with low levels of education)."
By many accounts, people are a lot less freaked out about the fall of Tiangong-1 this week than they were by Skylab back in 1979. Back then, some world leaders made statements to reassure the public and NASA fielded a flood of calls from some people that were "really quite panicky."
It probably helps that society is more accustomed to space technology at this point and that we've already been through Skylab's reentry, so we have some idea what to expect.
It's also worth keeping in mind that Skylab was also about 10 times the mass of Tiangong-1.
Still, all those bits of rational reassurance can only go so far.
There's an unusual lack of human control with Tiangong-1 that remains disconcerting. NASA was able to adjust Skylab's position until just before its reentry, attempting to aim it at least somewhat toward an unpopulated area. This time we're probably not going to know much until it's all over. There's a good chance Tiangong-1 will fall off of radar and into the ocean without any eyewitnesses ever catching its demise.
But there's also that teeny-tiny chance it strikes a populated area, and there's nothing that can be done to influence which outcome we actually get. This is a situation we don't encounter much as humans who prefer to at least delude ourselves into thinking we're in control, whether it's having our hands on the steering wheel or being able to see thunderheads rolling in and go the other direction.
A 1978 study titled "How Safe is Safe Enough" found that fear of driving, an unarguably dangerous and potentially lethal activity, is low because we feel in command while behind the wheel, even though we are not in control of our fellow drivers and other dangers on the road. In fact, other risk-perception research has found that more uncertainty in a situation typically translates into a more fearful response.
This response probably developed through the eons when uncertainty truly was a dangerous thing. If you didn't know what tribe or animal's territory you were wandering into thousands of years ago, there was probably good reason to worry.
But studies have shown that scared people can make dangerous decisions in the pursuit of regaining control. For example, in the wake of the 2001 terrorist attacks, many opted to drive long distances rather than fly, which is still a far safer means of travel despite the tragedy of September 11.
Perhaps it's fortunate, then, that the Tiangong-1 is so completely out of our control it's hard to imagine what you might do to ensure your safety, aside from spending the weekend in a bunker or taking a trip to Alaska or somewhere else north of the 43rd parallel.
Just keep in mind that you're much more likely to be hurt traveling to your bunker or another safe destination of your choice than if you simply stay in one place and monitor the end of Tiangong-1 online.
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