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Comment by dopeboy | Hacker News Reader

How's this work on an international coordination level? Does the Chinese space agency contact its counterparts and give a heads up?

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As signatories of the Outer Space Treaty they should give a heads up to the international community, and are liable for any damage that's caused by this event even if they provide warning (but could probably get out of it with enough political double talk).

What's interesting to me is that China haven't officially admitted to losing control of the station, they have only admitting to lost telemetry- so we must rely on external sensors to track it. I suspect (but don't have any real information on why) that they are doing this to avoid some sort of admission of guilt in the event that it ends up hitting a populated area. I'm not entirely sure but admitting you lost control of an orbiting school bus might be seen similarly to a kid that accidentally breaks your window with a baseball- it wasn't intentional, but that kid is still paying for the window. If your window gets hit by something, but the kid never admits that it was his ball ("gee mister, I lost my ball yesterday but I'm pretty sure it didn't go in your backyard"), then maybe he can get away without paying for it.

China notified the UN last year, and has kept them updated as required.

Here's one such notification: http://www.unoosa.org/oosa/en/oosadoc/data/documents/2017/aa...

Right, but what they've said is "we've lost TM and it's going to deorbit sometime in the future. We'll watch it and keep you posted." Which is all well and good until you realize what they haven't said, and they've had more than a year to say it:

What they haven't said is "the reason it's going to deorbit at an unspecified time instead of an exact time is because we've lost control so we can't do a controlled reentry burn to have it splash harmlessly in the Pacific. So if it puts a few redhot hunks of ceramic through an apartment building there's nothing we can do. Sorry."

Everyone knows they've lost control, and it's not the first time a country has lost control of a satellite. But maybe they get some legal benefit out of not admitting the loss of control. Because otherwise they should confess, it's not like this is the first time a country has lost control of a satellite.

None really for this one. They're not controlling the descent at all as far as anyone has been able to tell, there's just been a steady degradation of the orbit since it's last reboost years ago.

China, in typical China fashion, denied they lost control of the station right up to the end.

"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."

https://www.cbsnews.com/news/tiangong-1-tracking-the-chinese...

what if that is their design and everything is going well with the plan? so well it didn't require a noticeable correction since the orbit move a year ago...

That's probably impossible to do. Slight variations in atmospheric densities even in the last days/weeks leading up to the final reentry can change the final reentry time by 1/6th or more of an orbit. Wired did an article about a small simplistic model check it out. So managing a 'controlled' reentry from 2+ years out is just too complex to be done now, maybe ever it depends on a lot of different variables.

https://www.wired.com/story/you-can-model-chinas-tiangong-1-...

For further example: as of right now ESA still gives a 4 hour window for the reentry which is a really wide swath of the Earth that it could fall onto.

https://twitter.com/esa/status/980492830081679361

If it falls in Australia, the Chinese will probably have to pay a fine. But they can just not pay, I think the Americans never did for Skylab.

The fine that was levied on NASA was more tongue in cheek than serious. It was only for $400 and was from a local council.

NASA didn't, but IIRC a 3rd party paid it out, sourced from donations.

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