Countdown to impact
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I've been casually watching the updated predictions on where China's rocket will fall. Current prediction is off the east coast of Africa in about 36 hours from now:
A few days ago it was off the west coast of Mexico, then southwest of Australia.
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@boomzilla Looking at that map and marker, I want it to go down, say, half an hour later. As close to Beijing as feasible.
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@PleegWat said in Countdown to impact:
I want it to go down, say, half an hour later. As close to Beijing as feasible.
Would Wuhan be OK, too?
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Anyway, living at 50°N, I am in a rather safe place.
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@BernieTheBernie said in Countdown to impact:
Anyway, living at 50°N, I am in a rather safe place.
Yeah but there's no air conditioning, is there.
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@Gribnit I'm 51° north. We get maybe a week per year above 30°C.
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And now it's back out to the east of Australia:
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This post is deleted!
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@PleegWat said in Countdown to impact:
I'm 51° north. We get maybe a week per year above 30°C.
I'm further north than that. What is this concept called “30°C”?
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@dkf said in Countdown to impact:
@PleegWat said in Countdown to impact:
I'm 51° north. We get maybe a week per year above 30°C.
I'm further north than that. What is this concept called “30°C”?
It’s what they set the interrogation room thermostat to in order to torture northerners
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@dkf said in Countdown to impact:
@PleegWat said in Countdown to impact:
I'm 51° north. We get maybe a week per year above 30°C.
I'm further north than that. What is this concept called “30°C”?
303.15K.
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Can someone explain to me how it's possible we can precisely predict movements of celestial bodies billion miles away decades in the future, but can't tell which continent a free-falling rocket will hit the next day?
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@Gąska Because with large celestial bodies, being a few miles off don't matter squat. With falling debris, being a few miles off can be a matter of life or death.
In other words, there is error, but it's under-reported for the former.
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@Gąska Air resistance is a pain. We need to send in a massive surge and end that resistance once and for all!
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@coderpatsy said in Countdown to impact:
@Gąska Because with large celestial bodies, being a few miles off don't matter squat. With falling debris, being a few miles off can be a matter of life or death.
I could understand a few miles. But a few days ago it was predicted to land west of Mexico, then east of Africa, and now it's east of Australia. How is that possible?
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@dkf said in Countdown to impact:
@PleegWat said in Countdown to impact:
I'm 51° north. We get maybe a week per year above 30°C.
I'm further north than that. What is this concept called “30°C”?
Unseasonably cool.
Filed under:
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@Gąska said in Countdown to impact:
Can someone explain to me how it's possible we can precisely predict movements of celestial bodies billion miles away decades in the future, but can't tell which continent a free-falling rocket will hit the next day?
It depends very much on air friction. Atmospheric friction at that altitude is tiny, but not zero. (If it were zero, the orbit wouldn't decay, and it would stay in orbit.) Fluctuations in that tiny amount of friction are difficult to estimate. The atmosphere expands and contracts, and that changes the amount of friction. This depends on temperature, solar radiation, and probably other stuff the
has chosen not to look into. The object's own orientation with respect to the direction of travel through the thin atmosphere also affects the amount of friction.The high speed of the rocket body means it orbits the Earth roughly every 90 minutes and so a change of just a few minutes in reentry time results in reentry point thousands of kilometers away.
The Long March 5B core stage’s orbital inclination of 41.5 degrees means the rocket body passes a little farther north than New York, Madrid and Beijing and as far south as southern Chile and Wellington, New Zealand, and could make its reentry at any point within this area.
The world has gone through this before, most notably back in 1979 with Skylab. It massed 76 tons, total, and several pieces of it were sturdy enough that they were believed likely to survive reentry and impact the ground.
The largest and most famous incident was the 1979 reentry of NASA’s 76-ton Skylab, whose uncontrolled reentry scattered debris across the Indian Ocean and Western Australia.
For the last 30 years or so, large objects like this are usually maneuvered out of orbit in a controlled fashion, rather than being allowed to fall wherever friction happens to drag them down.
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LOL, predictions are all over the place. Even this close to re-entry.
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@PleegWat said in Countdown to impact:
@dkf said in Countdown to impact:
@PleegWat said in Countdown to impact:
I'm 51° north. We get maybe a week per year above 30°C.
I'm further north than that. What is this concept called “30°C”?
303.15K.
Rankine would have been preferable here.
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@boomzilla said in Countdown to impact:
LOL, predictions are all over the place. Even this close to re-entry.
I mean it's not rocket... science... per-se it's ballistics
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@HardwareGeek so it’s basically a chaotic system with regard to the initial conditions. The rocket’s current state and the earth’s atmosphere at every point in the trajectory cannot be determined to a high enough precision that rounding errors do not completely change the results.
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@topspin Already in the tweet it says "03:30 UTC ± 4 hours". Since the thing makes a full circle around the earth each 1.5 hours, you can't really predict anything.
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@Grunnen said in Countdown to impact:
@topspin Already in the tweet it says "03:30 UTC ± 4 hours". Since the thing makes a full circle around the earth each 1.5 hours, you can't really predict anything.
Everything on Red.
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@Gribnit said in Countdown to impact:
@Grunnen said in Countdown to impact:
@topspin Already in the tweet it says "03:30 UTC ± 4 hours". Since the thing makes a full circle around the earth each 1.5 hours, you can't really predict anything.
Everything on Red.
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@topspin said in Countdown to impact:
@Gribnit said in Countdown to impact:
@Grunnen said in Countdown to impact:
@topspin Already in the tweet it says "03:30 UTC ± 4 hours". Since the thing makes a full circle around the earth each 1.5 hours, you can't really predict anything.
Everything on Red.
Are the big books tracking this, though, seriously? The freeform gambling rooms in Vegas seem like they should have this available.
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@Gąska said in Countdown to impact:
Can someone explain to me how it's possible we can precisely predict movements of celestial bodies billion miles away decades in the future, but can't tell which continent a free-falling rocket will hit the next day?
Scott Manley might be the guy to tell you:
https://youtu.be/afGFmAljL5EAs others already have said, atmosphere plays a large factor. The thing might be tumbling.
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@Gąska said in Countdown to impact:
How is that possible?
It's probably tumbling and where it lands will depend on when exactly it hits enough of the atmosphere, whose exact extent is unknown anyway (that's variable).
Oh.
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It landed in the Indian Ocean
'Out-of-control' Chinese rocket has landed in the Indian Ocean
Some criticised China for not making an effort to control the descent but China maintained it was "not worth panicking about".
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@Jaloopa rien ne va plus. No winners.
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@topspin said in Countdown to impact:
@Jaloopa rien ne va plus. No winners.
It's fair to say that everyone in a (land-based) place it could have fallen on but didn't(1) was a sort of minor winner.
(1) Example: Peking.
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@Steve_The_Cynic said in Countdown to impact:
@topspin said in Countdown to impact:
@Jaloopa rien ne va plus. No winners.
It's fair to say that everyone in a (land-based) place it could have fallen on but didn't(1) was a sort of minor winner.
(1) Example: Peking.
Mercy deferred is mercy denied.
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@Steve_The_Cynic said in Countdown to impact:
@topspin said in Countdown to impact:
@Jaloopa rien ne va plus. No winners.
It's fair to say that everyone in a (land-based) place it could have fallen on but didn't(1) was a sort of minor winner.
(1) Example: Peking.
Eh, it would’ve been fun in the unlikely case it had crashed on the US. That certainly would still be in the middle of nowhere (anything else is unlikely) so nobody would be harmed, but it might have sent some unfriendly words Peking’s way.
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@topspin said in Countdown to impact:
@Steve_The_Cynic said in Countdown to impact:
@topspin said in Countdown to impact:
@Jaloopa rien ne va plus. No winners.
It's fair to say that everyone in a (land-based) place it could have fallen on but didn't(1) was a sort of minor winner.
(1) Example: Peking.
Eh, it would’ve been fun in the unlikely case it had crashed on the US. That certainly would still be in the middle of nowhere (anything else is unlikely) so nobody would be harmed, but it might have sent some unfriendly words Peking’s way.
Like a $250 littering fine?
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@PleegWat said in Countdown to impact:
@topspin said in Countdown to impact:
@Steve_The_Cynic said in Countdown to impact:
@topspin said in Countdown to impact:
@Jaloopa rien ne va plus. No winners.
It's fair to say that everyone in a (land-based) place it could have fallen on but didn't(1) was a sort of minor winner.
(1) Example: Peking.
Eh, it would’ve been fun in the unlikely case it had crashed on the US. That certainly would still be in the middle of nowhere (anything else is unlikely) so nobody would be harmed, but it might have sent some unfriendly words Peking’s way.
Like a $250 littering fine?
Possibly bigger in Texas, given their slogan.
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@Jaloopa said in Countdown to impact:
Some criticised China for not making an effort to control the descent but China maintained it was "not worth panicking about".
If U.S. were to fish up the remains of that rocket, and start publishing close-up photos exhibiting the tech... Maybe even reviewing their technical solutions to common problems...
That might make China rethink about dropping the rocket just anywhere.
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@acrow said in Countdown to impact:
That might make China rethink about dropping the rocket just anywhere.
If the stage indeed started tumbling out of control after detaching, they might have to design better rockets in the first place.
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@cvi why? It's not like they care about any potential casualties.
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@acrow said in Countdown to impact:
@Jaloopa said in Countdown to impact:
Some criticised China for not making an effort to control the descent but China maintained it was "not worth panicking about".
If U.S. were to fish up the remains of that rocket, and start publishing close-up photos exhibiting the tech... Maybe even reviewing their technical solutions to common problems...
That might make China rethink about dropping the rocket just anywhere.
Maybe I can eBay it.
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@Gąska said in Countdown to impact:
@cvi why? It's not like they care about any potential casualties.
Nah, but they don't like being worse at things than the rest of the world.
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@cvi said in Countdown to impact:
@Gąska said in Countdown to impact:
@cvi why? It's not like they care about any potential casualties.
Nah, but they don't like being worse at things than the rest of the world.
This is why it's important to support beard-growing competitions.
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@cvi said in Countdown to impact:
@Gąska said in Countdown to impact:
@cvi why? It's not like they care about any potential casualties.
Nah, but they don't like being worse at things than the rest of the world.
They don't give a shit as long as you pay them for low quality garbage.
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Yes, you also need an ANSI/ISEA Z89.1-2014 (R2019)-compliant hard hat when working near falling rocket boosters.
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@boomzilla Question is: does that count as a illegal parking or a vehicle breakdown? (Guess you'd call the towing service either way.)
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@cvi I don't think a rocket ship meets the legal definition of a motor vehicle.
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@boomzilla Booster of unknown origin
CZ-5B Rocket Body (ID 48275) | The Aerospace Corporation
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