A Celestial Palace Falls to Earth
March 28, 2018 12:56 PM   Subscribe

In the next few days Tiangong-1, China's orbiting space station, (previously, previously, previously) will have an uncontrolled re-entry into the Earth's atmosphere. "It's not supposed to happen like this." You can track Tiangong-1's progress here.
posted by runcibleshaw (60 comments total) 24 users marked this as a favorite
 
"It's not supposed to happen like this." - your life and mine, Tiangong-1, your life and mine.

Ad Astra buddy.

oh shit, wait, no, not that, I mean, geez, sorry
posted by GuyZero at 12:59 PM on March 28, 2018 [15 favorites]


Fun tidbit at the end of the WaPo article:
Skylab itself, weighing in at 74 tons, made an infamous semi-controlled reentry in 1979. The spacecraft didn’t burn up as fast as NASA thought it would, so instead of landing in the ocean southeast of Cape Town, South Africa, its pieces scattered across southwest Australia.

One town even fined NASA $400 for littering. As far as we know, that fine was never paid.
posted by Salvor Hardin at 1:00 PM on March 28, 2018 [9 favorites]


Despite the NYT trying to imply the opposite, Tiangong-1's mass of 8506 kg is not that big. All the iterations of the Soyuz spacecraft from 1986 on were (and are) about 7200 kg. I mean, yeah, the Chinese have been careless about this, but we're not talking about huge flaming chunks spread over a wide area. It wouldn't be too surprising if nothing of any real size makes it to the ground.
posted by Quindar Beep at 1:05 PM on March 28, 2018 [1 favorite]


In the extremely unlikely chance you happen to see any satellite fall from space or otherwise come across wreckage of a satellite - it's a really good idea to keep your distance and stay upwind due to hypergolic fuels possibly leaking out of the wreckage. Dinitrogen tetroxide is some of the nastiest stuff that exists, chemically speaking, short of elemental fluorine.
posted by loquacious at 1:06 PM on March 28, 2018 [3 favorites]


Is it really possible for anything even remotely hypergolic to make it through reentry? Space shuttle tiles used to get to 1650 C on reentry and I'm going to go out on a limb and say the impact is probably going to thoroughly mix anything that hasn't already incinerated or oxidized already.
posted by GuyZero at 1:14 PM on March 28, 2018 [2 favorites]


I found the problem in the YouTube video linked from the aerospace.org article. It appears that the engineering team attached a schoolbus to the port side solar panel.

While this wouldn't affect aerodynamics in space, when the driver exited the vehicle to check tire pressure in March 2016, the students probably reset the radio frequency, thereby breaking contact with Earth. Happened all the time on my bus as a kid. Silly oversight by the Chinese.
posted by Abehammerb Lincoln at 1:19 PM on March 28, 2018 [17 favorites]


If it survives re-entry, I hope it lands on Peter Thiel.
posted by SansPoint at 1:21 PM on March 28, 2018 [23 favorites]


huge fan of the ESA graph that maps out the likely areas of re-entry for the Tiangong-1 and pairs it up with a population density according to latitude

looks like the highest probability are it plunging into an ocean or into a heavily populated landmass. and what an excellent geopolitical environment for an international incident to occur
posted by runt at 1:24 PM on March 28, 2018 [13 favorites]


2018 was the year that the Chinese space station went out of control. No one knew where it might land. It soared above the ozone layer like a lethal bird of prey. The whole world was alarmed. Claire couldn't care less.
posted by octobersurprise at 1:25 PM on March 28, 2018 [29 favorites]


From the WaPo article:

(By the way, you can see all of the stuff in space in real time, at the website stuffin.space.)

COOL and also wow that's a lotta stuff
posted by showbiz_liz at 1:34 PM on March 28, 2018 [11 favorites]


Is it really possible for anything even remotely hypergolic to make it through reentry?

Yes. It's a question of speed, mass and angle of re-entry. There have been cases of space debris (especially spherical tanks) making it to land remarkably intact. If you're storing your fuel and oxidizers in newer carbon composite tanks, they're more likely to survive rentry and breakup.

Especially-especially when you're talking about slow, uncontrolled low altitude de-orbits like this. We're not talking about the SST deliberately punching into the atmosphere at a full 17,000 MPH LEO speed, plus all of it's aerobraking mass suddenly breaking up.

And it doesn't take much hypergolic oxidizer to ruin someone's day/life, or a whole town of someone's.

Are you questioning if it's a good idea to not approach presumably fuming aerospace debris? No, no it's not.

Anyway, you don't have take my word for it, here's what the Aerospace.org site says about the subject:
What will this reentry look like?

Depending on the time of day and cloud visibility, the reentry may appear as multiple bright streaks moving across the sky in the same direction. Due to the relatively large size of the object, it is expected that there will be many pieces reentering together, some of which may survive reentry and land on the Earth’s surface. Some examples of reentries can be found here: video 1, video 2.

Are there hazardous materials on board?

Potentially, there may be a highly toxic and corrosive substance called hydrazine on board the spacecraft that could survive reentry. For your safety, do not touch any debris you may find on the ground nor inhale vapors it may emit.
Anyway, in the rare chance you ever see red vapor/smoke coming out of basically anything, and/or any kind of vapor/steam/smoke coming out of something that just fell out of the sky - get upwind and far away from it.
posted by loquacious at 1:38 PM on March 28, 2018 [14 favorites]


When I was 9 my friend and I had a Skylab watch, the night Skylab was supposed to re-enter. Even though we lived in New England, we were convinced it was going to come down in our neighborhood. So we had a sleepover, set up his telescope and, until his mom made us go to bed, we stood outside waiting for the station to re-enter. To our nine year-old minds, every little light or streak we saw in the sky was Skylab, crashing down in the backyard.

I hope there will be some dumbass nine year-old kids doing the same thing this time around.
posted by bondcliff at 1:39 PM on March 28, 2018 [40 favorites]


in the rare chance you ever see red vapor/smoke coming out of basically anything

Googling 'red vapor' just gave me a lot of vape juice retailers - deets on why this is the case? Just curious.
posted by showbiz_liz at 1:40 PM on March 28, 2018 [1 favorite]


Ad Astra buddy.

Ad Terra?
posted by Greg_Ace at 1:42 PM on March 28, 2018 [3 favorites]


Also, if people like satellite trackers, here's one of my favorites, with their tracking and observation data for Tiangong-1: Satflare.com.

This one is focused on visual tracking and interaction with satellites.

Check out the ISS/Zarya tracker and "flare" predictor, then set a location and go to the flare predictions tab.

These trackers give you stuff like star charts and ground tracks and higher magnitude visible flare passes so you know where to look in the sky for the ISS or other satellites zooming overhead.

The first time you actually see a really bright ISS/Zarya flyover it's just otherwordly. At first it's just a little dot of light, and it just keeps getting faster and faster until it's zooming overhead and it's obviously not an airplane at all, and is much, much higher and moving much faster.

There's also a few good ISS and iridium flare tracker for Android. You can set them up so they give you a bit of warning and an alert for a good flyover so you can just pop out and look at it, because they fly over in a brisk 20-30 seconds or so.

If it's clear out I usually spot the ISS a couple of times a week or month, and iridiums almost every night if I want to go look at 'em.
posted by loquacious at 1:49 PM on March 28, 2018 [7 favorites]


Are you questioning if it's a good idea to not approach presumably fuming aerospace debris? No, no it's not.

Well not really but it is pretty amazing that a tank of hydrazine can make it from orbit to ground intact. I wouldn't carry a closed vial of it across a parking lot.
posted by GuyZero at 1:54 PM on March 28, 2018 [1 favorite]


🙏🙏Mar-a-Lago🙏🙏
posted by Thorzdad at 1:56 PM on March 28, 2018 [62 favorites]


Googling 'red vapor' just gave me a lot of vape juice retailers - deets on why this is the case? Just curious.

Hypergolic fuels.

Dinitrogen tetroxide in particular.

Additionally, while there's lots of invisible gases that are bad for you, pretty much anything that has any sort of color is almost 100% likely to be super bad for you. Off the top of my head I can't think of any elemental or chemical gas that has any kind of color that's harmless, mildly friendly or even remotely safe. Examples: Yellows: Chlorines, ammonia, flourine. Browns: Bromines/bromides.
posted by loquacious at 1:58 PM on March 28, 2018 [1 favorite]


Googling 'red vapor' just gave me a lot of vape juice retailers - deets on why this is the case? Just curious.

Hydrazines are colorless, but I'm guessing N2O4 (the oxidizer in this fuel combination) is the red color, as it can decompose to NO2, which is red.
posted by Existential Dread at 1:59 PM on March 28, 2018


Just to quickly point out that dinitrogen tetroxide is not in fact a fuel, but an oxidiser
posted by Dysk at 2:14 PM on March 28, 2018 [4 favorites]


Sorry, the term I should be using is hypergolic propellant, not fuel. The propellant is the combination of fuel and oxidizer.
posted by loquacious at 2:19 PM on March 28, 2018 [2 favorites]


Yay rocket/space geeking! Also, bipropellant is such a fun word!
posted by Dysk at 2:24 PM on March 28, 2018 [2 favorites]


And while not falling from orbital speeds, the terminal speed for mostly empty cylinders isn't all that high so sometimes boosters land near population centers.
posted by Kyol at 2:37 PM on March 28, 2018


I wish I could find video of the John Belushi Skylab sketch.
posted by Splunge at 2:39 PM on March 28, 2018 [2 favorites]




So if we have the population density and the likely-to-come-down percentages, we can calculate the chance that it comes down on a piece of land that has a certain minimum population density, right? Is that number out there right now? I'm not able to calculate it, that's for sure.
posted by wires at 2:44 PM on March 28, 2018


Anyway, in the rare chance you ever see red vapor/smoke coming out of basically anything, and/or any kind of vapor/steam/smoke coming out of something that just fell out of the sky - get upwind and far away from it.

Well, there goes another plan for getting superpowers.
posted by Halloween Jack at 2:58 PM on March 28, 2018 [10 favorites]


> In the extremely unlikely chance you happen to see any satellite fall from space or otherwise come across wreckage of a satellite...

Obligatory?
posted by cjorgensen at 3:01 PM on March 28, 2018 [2 favorites]


Can tired overweight balding men even get superpowers? Asking for a friend. Fuck, I have no friends. Cover blown. Worst potential super hero ever.

Takes out CBT worksheet. Fills in another row.
posted by srboisvert at 3:29 PM on March 28, 2018 [19 favorites]


In many countries if a meteorite lands on your property, you own it. Wonder if the same applies to tanks of incredibly toxic gases falling from the sky
posted by ook at 3:30 PM on March 28, 2018 [1 favorite]


I also remember waiting around for Skylab to land in our backyard. I think someone said it was Jimmy Carter's fault.
posted by RobotVoodooPower at 3:38 PM on March 28, 2018 [3 favorites]


So you’re saying this is going to land on my house. 50/50 chance? Great.
posted by Don.Kinsayder at 3:40 PM on March 28, 2018


>In many countries if a meteorite lands on your property, you own it. Wonder if the same applies to tanks of incredibly toxic gases falling from the sky

You mean will you have to pay for the remediation if it lands in your driveway? I wouldn't be a bit surprised. I wonder if you could put some cinderblocks under it and tell people it just needs a little work...
posted by Sing Or Swim at 3:46 PM on March 28, 2018 [2 favorites]


I think someone said it was Jimmy Carter's fault.

It was 1979; Carter bore the blame for most everything.
posted by Iris Gambol at 4:13 PM on March 28, 2018 [3 favorites]


It was 1979; Carter bore the blame for most everything.

It's true. I remember very energetically and vocally blaming him for not getting a Big Wheel for Christmas that year. I'm also pretty sure he's the reason my mom never bought Fruity Pebbles and I was always eating weird puffed millet cereal that looked like it came packaged in a bread bag.
posted by loquacious at 5:35 PM on March 28, 2018 [9 favorites]


And while not falling from orbital speeds, the terminal speed for mostly empty cylinders isn't all that high so sometimes boosters land near population centers.

And this is part of how SpaceX boosters can manage reentry without a bunch of thermal shielding. They're not making orbital velocities by the time they start their flip and boostback burn and come back at speeds in (AFAIR) the 5-6,000 MPH range as opposed to the 15-18,000 MPH range, and then they manage that speed with a mix of aerobreaking, terminal velocity and retrofire burns.

But at the velocities they're dealing with they basically stop moving mid-trajectory, track back a bit and then fall out of the sky until the main landing retro burn and a few very small velocity/correction burns on the way down.

The boosters are basically running the same program as a semi-ballistic but aero-guided free falling bomb with grid fins with a landing sequence tacked on the end. And, of course, the nitrogen attitude control jets to keep it pointed the right way so the boosters and grid fins even work.

Most of the thermal damange you see on a landed Space-X booster is from the retro burns from the boosters. It's not primarily from atmospheric heating.

To put this into an even wilder perspective, given a perfectly spherical (or otherwise stable and not spinning) astronaut in a space suit, there's no major reason why you couldn't skydive and fall from space from, say, ISS heights in the 150-200 mile range as long as you weren't moving at orbital velocities.

Your terminal velocity falling straight down would be relatively low. You might hit mach 1.5, maybe even 2 from that height, but at that atmospheric density it doesn't really matter, and your speed would drop off very quickly as terminal velocity decreased.

And AFAIR NASA at one point was investigating this as an emergency escape and rescue system. Not only did the Shuttle have ejection seats at one point, they also had plans for these weird spherical rescue pods, and I remember seeing mockups and proposals about how to make pods that could either burn a lot of velocity or handle orbital re-entry speeds and still get a single astronaut back to earth.

Getting to/from space doesn't have to be a fiery, dramatic thing if you either have a low enough velocity or enough delta V to burn to take it real slow.

The only reason why rockets (and re-entries) are traditionally this high speed, dynamic, dangerous thing is because of the limitations of our engineering, our budgets and the limitations of chemical rockets. You have a limited window of mass and burn time to achieve orbit, and that means you have to get to orbit and stop burning fuel as fast as possible.

If you had something like a nuclear jet/rocket engine combo - which is a horrifying thing that has existed and apparently exists in some of Russia's newer death machines - you could climb out of the atmosphere and re-enter at quite leisurely velocities, if you were willing to overlook the hideous plume of hot, radioactive gases you were using as a thruster.
posted by loquacious at 5:54 PM on March 28, 2018 [10 favorites]


> loquacious:
"In the extremely unlikely chance you happen to see any satellite fall from space or otherwise come across wreckage of a satellite - it's a really good idea to keep your distance and stay upwind due to hypergolic fuels possibly leaking out of the wreckage. Dinitrogen tetroxide is some of the nastiest stuff that exists, chemically speaking, short of elemental fluorine."

Forget about that. Given what chemicals China has allowed into human food-oriented products, if a piece of that lands anywhere near me, I am, at the least, changing counties.
posted by Samizdata at 7:04 PM on March 28, 2018


One town even fined NASA $400 for littering. As far as we know, that fine was never paid.

If I send them four hundred kangaroo bucks, will they give me all the pieces of Skylab? Because they would be a damn BARGAIN.

Anyone want to chip in for a share?
posted by wenestvedt at 7:14 PM on March 28, 2018


> wenestvedt:
"If I send them four hundred kangaroo bucks..."

I hear male kangaroos can be quite vicious creatures, so I don't have any on hand.
posted by Samizdata at 7:42 PM on March 28, 2018 [1 favorite]


Oh God that millet cereal...
posted by aramaic at 8:17 PM on March 28, 2018 [3 favorites]


"Can tired overweight balding men even get superpowers? Asking for a friend. Fuck, I have no friends. Cover blown. Worst potential super hero ever."

One Punch Man.
posted by Sprocket at 8:52 PM on March 28, 2018 [1 favorite]


Unless the station's wreckage includes a strange green slime, I'm not worried.
posted by happyroach at 9:14 PM on March 28, 2018


I approve of the the turn this thread has taken.
posted by runcibleshaw at 9:15 PM on March 28, 2018 [1 favorite]


Looks like WaPo didn't read their own last link; NASA may not have paid the fine, but someone from the Southwest did, writing a big check to the Shire of Esperance. (Lots of neat pictures of space junk at this link.)
posted by Halloween Jack at 9:24 PM on March 28, 2018 [4 favorites]


I approve of the the turn this thread has taken.

Let's hope we can say the same of the spacecraft's incoming trajectory.
posted by Greg_Ace at 9:32 PM on March 28, 2018 [4 favorites]


Lots of neat pictures of space junk at this link.

So if I call my junk "space junk" and upload a buncha photos ...

Brilliant.
posted by oheso at 2:01 AM on March 29, 2018 [1 favorite]


Dang, beaten to it!
posted by wenestvedt at 3:14 AM on March 29, 2018


The altitude chart in the last link was really surprising to me, I didn't realise station keeping manoeuvres would be so major, or rather that they'd allow such a relatively large change in the orbit.
posted by lucidium at 4:47 AM on March 29, 2018


Of relevance
posted by ojemine at 5:03 AM on March 29, 2018


I think someone said it was Jimmy Carter's fault.

It was 1979; Carter bore the blame for most everything.


Plus he had a brother who liked to drink beer.
posted by parm=serial at 5:39 AM on March 29, 2018 [1 favorite]


These are giving me Skylab flashbacks. I was six and was convinced it was going to fall on my house and kill us all, because the news hyped for weeks that even the tiniest speck could crush a human. Basically, the complete opposite of bondcliff's experience. :)
posted by kimberussell at 6:31 AM on March 29, 2018 [2 favorites]


And AFAIR NASA at one point was investigating this as an emergency escape and rescue system. Not only did the Shuttle have ejection seats at one point, they also had plans for these weird spherical rescue pods, and I remember seeing mockups and proposals about how to make pods that could either burn a lot of velocity or handle orbital re-entry speeds and still get a single astronaut back to earth.

So, let's say each crew member has an emergency exit kit that included an aerodynamically shaped panel, more or less shaped like a surf-board...well, my question is, would it glow?
posted by mule98J at 10:03 AM on March 29, 2018 [3 favorites]


I have found various claims scattered around the tubes that the United States claims ownership in its own space debris, even if it conks you on the noggin. I will not bother posting any of these since I didn't find one that seemed Clearly Authoritative. However, I don't see how they could claim part of a Chinese satellite and I have no idea what would happen if it lands in another country. Except China. I have a guess about that one.
posted by Gilgamesh's Chauffeur at 3:09 PM on March 30, 2018


Re-entry projection is now Apr. 2, 00:18 UTC (4:18 a.m. EDT) ± 2 hours, which means it can be narrowed down to about 3 orbits. Looks like North America, Europe, and Australia are safe, while parts of South America, Africa, and Asia still lie within the potential re-entry zone. Although the best guess at this point is somewhere in the South Pacific.
posted by DevilsAdvocate at 12:08 PM on April 1, 2018 [3 favorites]


Well, thanks, Devil's Advocate. Not a single update to the thread for two days and then you come in and snipe me as I type. :)

I would just add two things:
  • 00:18UTC is actually 8:18EDT, so the predicted re-entry is between 6pm and 10pm on the East Coast.
  • My prediction: From that probability graph mentioned earlier, I think it spends more time at the extremal latitudes, so perhaps, based on those yellow and green orbits...
    If it lands before 8:18pm, then it will most probably land on the China-Mongolia border, or possibly in southern Chile/Argentina. If it lands after 8:18pm, then: Uzbekistan-Kazakhstan-Kyrgyzstan or the Pacific, just West of Chile.
posted by pjenks at 12:21 PM on April 1, 2018 [2 favorites]


00:18UTC is actually 8:18EDT

D'oh!! You're right, of course.
posted by DevilsAdvocate at 12:23 PM on April 1, 2018


Live updates from Daily Express. Here's the fun part: it may have already crashed, no one knows, at least no one who's saying anything. Recent entries (times listed are British Summer Time, UTC+1):

1.19am: Could the Tiangong-1 have already crash landed on Earth?

1.32am: Chinese space station is set to cross the Chile’s coast

1.36am: Tiangong-1 is set to pass over Uruguay within minutes.

1.42am: No reports have emerged of the Chinese space station crossing South America yet - has it already crashed?

1.47am: Tiangong-1 is set to cross the Ivory Coast and Ghana next

1.50am: Overcast weather in South America could be responsible for a lack of Tiangong-1 sightings
posted by DevilsAdvocate at 6:03 PM on April 1, 2018


Apparently still up:

2.00am: The Tiangong-1 soars over the Sahara Desert

The Chinese space station is currently flying over the Sahara Desert in Afria.

It is believed the station is traveling at a height of around 134kilometres.
posted by DevilsAdvocate at 6:09 PM on April 1, 2018


Apparently it has arrived (8:16 EDT in the Pacific):
@18SPCS: UPDATE: #JFSCC confirmed #Tiangong1 reentered the atmosphere over the southern Pacific Ocean at ~5:16 p.m. (PST) April 1. For details see http://www.space-track.org
h/t: @planet4589 (Jonathan McDowell, CfA)
posted by pjenks at 6:20 PM on April 1, 2018 [1 favorite]


@planet4589: The predictions were actually pretty good. [image]
posted by pjenks at 6:41 PM on April 1, 2018 [1 favorite]


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