
Falling Chinese Space Station to Crash This Weekend - awl130
https://www.popularmechanics.com/space/satellites/a19640957/falling-chinese-space-station-to-crash-this-weekend/
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teraflop
The predictions have narrowed considerably since the tweet in this article was
posted. This site has an up-to-date forecast:
[http://www.aerospace.org/cords/reentry-
predictions/tiangong-...](http://www.aerospace.org/cords/reentry-
predictions/tiangong-1-reentry/)

(You may need to click through to the full-resolution image and manually
refresh to see the latest updates.)

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sduclos
woaw this .png is updated in real-time
[http://www.aerospace.org/CORDSuploads/TiangongStoryboard.png](http://www.aerospace.org/CORDSuploads/TiangongStoryboard.png)

From 11:05 to 11:25 UTC the perigee dropped ~10km (165 to 153)

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kurthr
They are blocking repeated hotlinks to the .png based on referrer.

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jgh
interesting that they have pretty much no idea where it will end up, i thought
they'd be able to estimate that a bit.

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sephamorr
I think the best analogy is a roulette wheel. You know about when it's going
to stop, but that doesn't help much to analyze where.

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Lozzer
I think you'd enjoy the book "The Newtonian Casino".

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wallace_f
>this morning, Tiangong-1 was orbiting between 178 and 189 km (117 mi.) in
altitude, having descended 7 km in the past 24 hours

The Wikipedia page lists its intended perigee and apogee at 168-178km. So
either Wikipedia, or the article, are mistaken.

For reference, Salyut, the old Russian space station, was in orbit at
220-280km. The ISS and most others orbit around at a little over 400km.

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lordelph
You're looking at it's current orbital parameters - if you look further down
you'll see how the orbit degraded from approx 350km in 2017

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elijahparker
The Sky Guide iOS app (and likely others -- it's just the one I have) shows
the path if you search for Tiangong-1. From my location here in MN, the next
time it is will be above the horizon is Monday morning around 4:50am. It
leaves only a very slim chance of seeing anything from here, but I'll have a
camera running on my roof just in case.

Still, I wonder if the data in the app is updated regularly enough to account
for the recent changes, or if it's just showing the original orbit?

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dopeboy
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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rtkwe
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.

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gcb0
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...

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rtkwe
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-...](https://www.wired.com/story/you-can-model-chinas-
tiangong-1-space-station-crash/)

~~~
rtkwe
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](https://twitter.com/esa/status/980492830081679361)

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dis-sys
could be fun if someone picks up some debris and put it on ebay for auction.

given that the international treaty explicitly states that the nation which
launched such stuff should be responsible for its possible reentry damages, is
there any international laws or treaties stating that the debris still legally
owned by the nation that launched it?

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ansible
I guarantee there will be fraudulent sellers though.

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ChuckMcM
I wish there was a twilo service that would text me when it starts its last 2
or 3 orbits.

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kawfey
same, or a twitter profile or service that would notify everyone when it
actually happens, and if it happens to be over a populated area, warn people
below it in a timely manner that they might get hit with a bolt or something.

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gambiting
I'm just curious how is that information useful at all. A bolt falling from
space will penetrate any house, so I guess you'd need an underground bunker to
protect yourself - but then the chances are so incredibly low, is it worth
bothering with?

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ChuckMcM
For me, it's not so much get out of the way, as it is to look up and observe
it directly. On its penultimate orbit it should be observable all along its
orbit and when it does de-orbit there is probably a 2500 mile wide swatch
where you will get to see some portion of its disintegration. These were
pictures of Mir : [http://news.bbc.co.uk/2/hi/asia-
pacific/1238009.stm](http://news.bbc.co.uk/2/hi/asia-pacific/1238009.stm) for
example.

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joering2
Honest question; there is a nuclear reactor about 10 miles from new york city;
how is it protected against such sattelite smashing at the top of the dome?
Wouldnt that be Chernobyl times 1,000 ? And does new york city have a solid
plan on evacuating 8 million people off the island in some reasonable amount
of time?

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zupa-hu
Why the downvotes? That's a totally legit question. Unexpected events happen
all the time. Yes, the probability of this single event happening is small,
but the sheer number of unexpected events that can happen around the world
makes it likely that some of them will happen. I'd rather live in a place
where asking these questions won't get you burned.

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burfog
Wasn't me, but I can take a guess:

1\. absurdly low probability

2\. power plants are built to withstand airliner crashes having far more
energy

3\. it'll be insignificant debris, broken smaller than pieces of that space
shuttle

4\. the comment smells like nuclear fearmongering

It may be wrongly assumed that everybody here is nerdy enough to know all
these things.

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zupa-hu
Interesting, I didn't know power plants were built to withstand airplane
crashes. If that's true, that would be a great answer.

As for 1., sure, but still (probability x damage) makes it nevertheless
reasonable to consider it, even if it is later dismissed.

4\. - agree, and that's my problem. Sounds like [1].

[1] [http://www.paulgraham.com/say.html](http://www.paulgraham.com/say.html)

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skookumchuck
Chance of MetalStorm: 100%

