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Traditional Catholic Faith => General Discussion => Topic started by: Maria Regina on March 30, 2018, 04:55:23 PM

Title: Tiangong's Uncontrolled Re-entry
Post by: Maria Regina on March 30, 2018, 04:55:23 PM

China said that they had planned on a controlled descent, but then advised the United Nations that they had lost control.

What is the truth? Does China plan on striking a target and then blaming it on an uncontrolled ascent to avoid liability?

If the space station, the size of a school bus, suffers an uncontrolled descent, when will it arrive and where? The latest updates show the reentry will occur on Easter Sunday, April 1, 2018. Since we do not know where it will land, it would be  great idea to go to Holy Confession beforehand.

For the latest updates, please see http://blogs.esa.int/rocketscience/2018/03/26/tiangong-1-reentry-updates/

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Update 30 March 2018

The current estimated reentry window runs from the night of 31 March to the late evening of 1 April (in UTC time); this is highly variable.

Today’s new forecast is a noticeable change from that of yesterday, and is due to solar activity.

One of the main reasons why it is so difficult to make an accurate reentry predictions (http://blogs.esa.int/rocketscience/2018/03/28/why-its-tough-to-predict-reentries/), even if just a few days in advance of an expected reentry, materialised during the last 24 hours.

A high-speed stream of particles from the Sun, which was expected to reach Earth and influence our planet’s geomagnetic field, did, in fact, not have any effect, and calmer space weather around Earth and its atmosphere is now expected in the coming days.

This means that the density of the upper atmosphere, through which Tiangong-1 is moving, did not increase as predicted (which would have dragged the spacecraft down sooner) and hence the ESA Space Debris Office has adjusted the predicted decay rate.

This implies that the new (and still uncertain) reentry window has shifted to later in the day on 1 April.

Title: Re: Tiangong's Uncontrolled Re-entry
Post by: Smedley Butler on March 31, 2018, 10:18:54 AM

Track it live:


www.heavens-above.com/GroundTrack.aspx

Title: Re: Tiangong's Uncontrolled Re-entry
Post by: Neil Obstat on April 01, 2018, 06:38:14 PM

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So now flat-earthers suddenly are okay with satellites?
Can't make up your mind? Or is your mind always changing anyway?
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Maybe it changes so much you can't keep track of it.
But you think you can keep track of a satellite that you said doesn't exist?
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You can deny the existence of satellites all you want, and one falling can still kill you.
You don't have to believe in satellites to die when you get hit by one.
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Title: Re: Tiangong's Uncontrolled Re-entry
Post by: Maria Regina on April 01, 2018, 06:52:53 PM

It is estimated that the space debris will fall into the Southern Pacific Ocean perhaps 1000 or more miles off the coast of South America.

http://www.aerospace.org/CORDSuploads/TiangongStoryboard.png

Estimated time of impact will be in one hour and 20 minutes from now.

Title: Re: Tiangong's Uncontrolled Re-entry
Post by: Neil Obstat on April 01, 2018, 08:00:12 PM

Quote from: Maria Regina on April 01, 2018, 06:52:53 PM

It is estimated that the space debris will fall into the Southern Pacific Ocean perhaps 1000 or more miles off the coast of South America.

http://www.aerospace.org/CORDSuploads/TiangongStoryboard.png

Estimated time of impact will be in one hour and 20 minutes from now.

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The altitude of this thing is going up and down like a yo-yo.
They're saying it will crash when its altitude gets to about 100 km above earth.
But it's been up and down between 136 km and 145 km all afternoon today.
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https://www.wired.com/story/you-can-model-chinas-tiangong-1-space-station-crash/
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AT SOME POINT this week, the Chinese space station Tiangong-1 is going to crash down to Earth. When and where? We can't know for sure. And for that, we have physics to blame.
Tiangong-1 (https://en.wikipedia.org/wiki/Tiangong-1) is in orbit around the Earth at an altitude of about 138 miles. At first approximation, there is only one force acting on the space station—the gravitational pull from the Earth. This gravitational force pulls the space station towards the center of the Earth so that it moves in a mostly circular orbit. It's just like taking a ball on a string and swinging it around your head. The string pulls the ball so that it moves in a circle.
But wait! There's actually more than just the gravitational force. We like to pretend that outer space is an empty vacuum—but there are plenty of gases up there. And in the case of objects like Tiangong-1 in low Earth orbit, there are also still some atmospheric effects from the Earth's air. Oh sure, the air is super thin up there, but even a little bit of air resistance can make a difference over a long time. In fact, this is why the International Space Station gets an occasional reboost (https://www.wired.com/2013/04/atv-reboost-homework/) so that it doesn't slow down from the interaction with the air.
This tiny air resistance force pushes on the space station in the opposite direction of its motion. It's just like sticking your hand out the window of a moving car—but in space. This backwards pushing force decreases the speed of the space station so that it has a lower orbit. Oh, and what happens when the orbit gets lower? Yup, the object moves further into the atmosphere where there is even more air and greater air resistance. This can quickly lead to a runaway effect that heats up the object—so much that most of it will burn up during re-entry.
Now, if the basic physics of re-entry is understood, then why don't when know when and where the Tiangong-1 will land? The short answer is that the motion of the space station is very sensitive to initial conditions. Let me explain this by making a model of something similar to the Tiangong-1 in low Earth orbit.
When building something, it's best to start off simple. Here is a numerical model for an object in orbit around the Earth with no air resistance (here is an example of the physics from an older post (https://www.wired.com/2015/03/glowscript-tutorial-8-gravity-orbits/)). Note: You can indeed rotate your view here. Just right-click-drag (or ctl-click-drag) to view the orbit from another angle (for fun). If it stops, just click the "play" button to start it again. Oh, and the orbital height is to scale, but the size of the space object is greatly exaggerated so that you can see it.
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[go to source site to see the video]
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Now I want to add an air resistance force to the orbiting object. This air resistance force will depend on the size and shape of the object, the velocity of the object, and the density of air. It's that last one, the air density, that's the tough part for our purposes. Of course as you get farther from the surface of the Earth, the air density decreases, but getting the density as a function of altitude isn't so easy. Fortunately, someone has already created such a density model—you can check it out here (https://www.grc.nasa.gov/www/k-12/airplane/atmosmet.html).
I'll skip over the details but there should be enough comments in the code (https://trinket.io/glowscript/d1d058e923) for you to figure things out. I won't include the visualization since it basically looks the same as the previous one except this time it eventually "crashes." Instead, I will just show you a plot of the altitude as a function of time.
(https://media.wired.com/photos/5abceddd1241350ba90563e1/master/w_480,c_limit/orbitgraphcrash1.png)
Notice that with these initial conditions, it took a little over 8,000 seconds to crash. But what happens if I change the atmospheric density just a tiny little bit? (This isn't a totally crazy idea; the Earth's atmospheric density actually changes all the time depending on the weather (https://www.spaceacademy.net.au/watch/debris/atmosmod.htm)). So let me modify the density function for just the very highest altitudes—just a super tiny bit. This is such a small atmospheric change, you can barely see it. Here is a plot of the density as a function of altitude for my two atmospheric models.
(https://media.wired.com/photos/5abcedf9624d1d6458b788dd/master/w_640,c_limit/barelydifffdensity.png)
Now when I run two identical objects with the exact same initial conditions (except for the atmospheric density), I get the following.
(https://media.wired.com/photos/5abcee04768d7859929e74a7/master/w_480,c_limit/supertinyorbitdifference.png)
Here you can see that the object with slightly lower air density crashed about 16 minutes after the other object (here is the code if you want to play with it (https://trinket.io/glowscript/b899931d3e)). That might not seem like a big difference, but it is. Remember, this is just a model of orbiting objects. I created it so that they would "crash" in a reasonable amount of time. In reality something like Tiangong-1 is in an orbit such that it is influenced by the air drag over a very long time by a very little amount. Any tiny changes to the atmosphere will make huge differences in the final outcome. And that's just modeling one variable that could impact its trajectory.
So no, we don't know exactly when and where the Tiangong-1 will crash. We have a fairly good idea of its current altitude and velocity (but not exactly), but we don't have a perfect model for the density of air. (It actually gets worse: I used a model for air drag that most certainly does not apply to cases where the density is so low and the speed is super high.) Here's the good news, though: While physics is your enemy when it comes to knowing the space station's landing site, statistics is your friend when it comes to knowing if it'll hit you. It won't. You, after all, are a very tiny person on a very large planet.

Title: Re: Tiangong's Uncontrolled Re-entry
Post by: Maria Regina on April 01, 2018, 08:13:15 PM

Did Tiangong crash?

I visited http://www.aerospace.org/cords/reentry

Sure, there is the desktop showing the predicted crash site in the Southwestern Pacific, near South America,  but all the other parameters are now gone.

So what has happened?

Title: Re: Tiangong's Uncontrolled Re-entry
Post by: Neil Obstat on April 01, 2018, 08:19:43 PM

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https://www.express.co.uk/news/science/939774/Chinese-space-station-crash-tracker-Tiagnong-1-watch-live-stream-path-tracking

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The European Space Agency previously suggested the window centered at around 11.25pm GMT on April 1, but the variable window runs from the afternoon of April 1 to the early morning on April 2.
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You can watch the Chinese space station online through a robotically controlled telescope at The Virtual Telescope Project (https://www.virtualtelescope.eu/webtv/).
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The telescope started live coverage on Wednesday, March 28 at 12pm GMT and the webcast will feature live views of the space station in partnership with the Tenagra Observatories in Arizona as it plummets toward Earth.
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No one knows for sure where debris may land though many experts believe much of the station will burn up during re-entry.
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(https://cdn.images.express.co.uk/img/dynamic/151/590x/Chinese-space-station-tracker-939774.jpg)
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The Virtual Telescope Project said: “The Tiangong-1 Chinese Space Station is reentering our atmosphere soon.
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“Next 28 March, the Virtual Telescope Project and Tenagra Observatories offer you the unique chance to see it during one of its very last passage across the skies.
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“You can join us online, via the internet, from the comfort of your own home.
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“The Virtual Telescope Project and Tenagra Observatories, on behalf of their partnership, offer you the opportunity to see the Tiangong 1 station during one of its final passes across the stars."
.        _________________________________________________________________________

From the  Virtual Telescope Project website:

https://www.virtualtelescope.eu/webtv/
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https://youtu.be/hFWaEdXjvlw
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The voice of the speaking man on the video above is very interesting.
He has a foreign accent, but I'm not sure where he's from.
He sounds like a mix between eastern European and Japanese.
It would help if I could see his face!
But what he says -- in English -- is quite informative.
I highly suggest you check it out. This is happening NOW.
And the broadcast is free.
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But you can subscribe if you really like it.
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He says they are conducting a new experiment and they have no idea what the outcome will be.
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They have just started live images, waiting for the station to be a few degrees above the horizon.
"Let's hope we will see this right away.... just checking we are hoping we have everything ready.... okay
It should be appear in a few minutes .. I hope we can track this extremely difficult project right now ....
in southwestern Arizona ... very, very AArd (he means hard).... our telescope tracking it... not sure why we are not tracking... let me try again ... doing very critical things, my friends, but, you know... keeping the finger cross-ed..."
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Keeping his finger cross-ed.

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I think he's Chinese but he pronounces the L in "could". So his English is learned from books and classroom, not in practice.
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I knew a Korean man who learned English in Korea out of books and he pronounced the P in "receipt." 
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Title: Re: Tiangong's Uncontrolled Re-entry
Post by: Maria Regina on April 01, 2018, 08:38:02 PM

CBS Radio just announced that the Chinese spacecraft has crash landed in the South Pacific.

The European Space Agency just announced:
reentry was at 0016 UT
-13.6 degrees latitude
195.7 degrees longitude
South Pacific Ocean

Title: Re: Tiangong's Uncontrolled Re-entry
Post by: Neil Obstat on April 01, 2018, 08:44:36 PM

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This tracking site (http://www.heavens-above.com/GroundTrack.aspx) shows elevation right now at 137.3 km, north of New Zealand, going east southeast toward the South Pacific and South America.
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Height above ground is currently increasing, to 139 km, coordinates 20.9 south, 177 west.
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Now it's at 25 deg. south, 172 deg. west.
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This longer time to edit is great!  HAHAHAHA
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Update: 28 south, 167 west.
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30 south, 164 west.
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32 south, 162 west.  Elevation 143 km -- going up, folks.
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Going to cross over Santiago, Chile in about 15 minutes.
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Hey, happenby, go see the space station hurdling, careening, lunging, speeding across the sky.
It looks like it's standing still. How could it be going over 1,000 mph?
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The tracker puts its path right over  Uruguay. I know a guy who moved down there. Maybe I should call him up, and tell him to get into the basement real quick.
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41 south, 135 west, 146 km high.

Title: Re: Tiangong's Uncontrolled Re-entry
Post by: Maria Regina on April 01, 2018, 08:53:12 PM

Quote from: Neil Obstat on April 01, 2018, 08:44:36 PM

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This tracking site (http://www.heavens-above.com/GroundTrack.aspx) shows elevation right now at 137.3 km, north of New Zealand, going east southeast toward the South Pacific and South America.
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Height above ground is currently increasing, to 139 km, coordinates 20.9 south, 177 west.
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Now it's at 25 deg. south, 172 deg. west.
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This longer time to edit is great!  HAHAHAHA
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Update: 28 south, 167 west.
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30 south, 164 west.
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32 south, 162 west.  Elevation 143 km -- going up, folks.
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Could this site above be an April's Fools Joke?

The re-entry was at 5:16 PM PDT today or 0016 UT on April 2, 2018.

Yes, I really appreciate the extra 15 minutes to edit posts.

Title: Re: Tiangong's Uncontrolled Re-entry
Post by: Neil Obstat on April 01, 2018, 09:00:00 PM

Quote from: Maria Regina on April 01, 2018, 08:53:12 PM

Could this site above be an April's Fools Joke?

The re-entry was at 5:16 PM PDT today or 0016 UT on April 2, 2018.

Yes, I really appreciate the extra 15 minutes to edit posts.

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Where are the flat-earthers claiming that satellites are ALL April Fools' jokes?
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All I see is what the site has on it:
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Height above ground	146.7 km
Position	42.6°S, 123.3°W
Spacecraft in sunlight?	true
Orbital Elements Epoch

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They would have to be making it up for the elevation and coordinates to be constantly changing.
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The virtual telescope spokesman was really excited, saying this is the best success he has had in his entire life with live telescope capture of a re-entering satellite. He thought the brightness of the station was due to its heating up in the atmosphere but later he said it was due to the sunlight shining on it.
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Then he said China (who owns the station) said they expect re-entry to take place sometime tomorrow, April 2nd, plus or minus one day.
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Other sites claimed to have a 6 hour margin of error. I don't know who to believe.
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The margin of error is a very important part of this prediction.
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Why bother with a new post when you can edit the old one?! HAHAHAHA
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Height above ground                 143.5 km
Position                                    36.3°S, 80.0°W
Spacecraft in sunlight?                    false
Orbital Elements Epoch              2018-Apr-01 09:07:05

Note: "Epoch" refers to the ephemerides or data set of the satellite, which tells you where it's at and stuff.

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It just passed Santiago and is over the Andes mountains headed for Brazil.. crossing Argentina...
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Height above ground           139.9 km
Position                          27.5°S, 62.9°W
Spacecraft in sunlight?          false
Orbital Elements Epoch        2018-Apr-01 09:07:05

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Height above ground         137.6 km
Position                        21.3°S, 54.4°W 
Spacecraft in sunlight?          false
Orbital Elements Epoch        2018-Apr-01 09:07:05

Title: Re: Tiangong's Uncontrolled Re-entry
Post by: Neil Obstat on April 01, 2018, 09:17:52 PM

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I just noticed that the time stamp doesn't change, but the other numbers do...
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Height above ground         135.9 km
Position                     16.1°S, 48.1°W
Spacecraft in sunlight?       false
Orbital Elements Epoch      2018-Apr-01 09:07:05
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I have no idea how long it's been at 09:07:05 
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Title: Re: Tiangong's Uncontrolled Re-entry
Post by: Maria Regina on April 01, 2018, 09:30:24 PM

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http://www.dailymail.co.uk/news/article-5567801/Chinese-space-station-hurtling-Earth-set-enter-atmosphere-hours.html

BREAKING NEWS: Chinese space station smashes to Earth at 17,000mph off the coast of Tahiti: Nine-ton installation the size of a school bus comes crashing into the atmosphere in a huge fireball and just misses tropical paradise

• The chances of any one person being hit by its debris are considered to be less than one in a trillion

By Tim Stickings For Mailonline (http://www.dailymail.co.uk/home/search.html?s=&authornamef=Tim+Stickings+For+Mailonline) and Rory Tingle For Dailymail.com (http://www.dailymail.co.uk/home/search.html?s=&authornamef=Rory+Tingle+For+Dailymail.com)
Published: 16:08 EDT, 1 April 2018 | Updated: 22:08 EDT, 1 April 2018

Chinese space authorities say its defunct Tiangong 1 space station re-entered the earth's atmosphere over the South Pacific and crashed near Tahiti early on Monday.

The craft re-entered the atmosphere around 8.15am Beijing time (0015GMT) and the 'vast majority' of it had burnt up upon re-entry, the China Manned Space Engineering Office said.

It had said shortly before that it was expected to re-enter off the Brazilian coast in the South Atlantic near the cities of Sao Paulo and Rio de Janeiro.

China's space authority said on Sunday that the station would hit speeds of nearly 17,000mph before disintegrating. They previously said its fiery disintegration would offer a 'splendid' show akin to a meteor shower.

Scientists monitoring the craft's disintegrating orbit had forecast the craft would mostly burn up and would pose only the slightest of risks to people. Analysis from the Beijing Aerospace Control Center showed it had mostly burned up.

Thank goodness it landed in the ocean. Sadly, it will contaminate the sea with heavy metals and contaminates.

China saved face this time.

Title: Re: Tiangong's Uncontrolled Re-entry
Post by: Maria Regina on April 01, 2018, 09:36:37 PM

Quote from: Neil Obstat on April 01, 2018, 09:17:52 PM

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I just noticed that the time stamp doesn't change, but the other numbers do...
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Height above ground         135.9 km
Position                     16.1°S, 48.1°W
Spacecraft in sunlight?       false
Orbital Elements Epoch      2018-Apr-01 09:07:05
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I have no idea how long it's been at 09:07:05
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I think that site is fake news and an April fool's day joke.
It is not official.

Notice that Samuel provided that website.

Title: Re: Tiangong's Uncontrolled Re-entry
Post by: Neil Obstat on April 01, 2018, 09:43:07 PM

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I'm seeing other sites concur Tiangong-1 re-entered and spashed into the South Pacific Ocean
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The reentry has been confirmed as 2018/04/02 00:16 UTC. Reentry occurred in the Pacific Ocean.
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That was about a half hour ago, 00:16 UTC (I'm at UTC -7 and it's 7:40 now).

Title: Re: Tiangong's Uncontrolled Re-entry
Post by: Neil Obstat on April 01, 2018, 09:46:56 PM

Quote from: Maria Regina on April 01, 2018, 09:36:37 PM

I think that site is fake news and an April fool's day joke.
It is not official.

Notice that Samuel provided that website.

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The page was one that displays logged-in data but I wasn't logged in so the page might have been going on a pre-set routine showing the data, but not changing the time since my location was not an input quantity.
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I thought I was watching a live stream of the virtual telescope guy but later I found I could watch the whole thing again, so it was recorded the first time I saw it. It had already happened.
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