B Chinese not sure where space station will land

[mfb]

Risk. That’s an open term. If the demise of Skylab was as badly planned as that of the Chinese station then my comment applies. If no money can be spared for suitable protective measures then a project should not fly.

What exactly makes you think it was badly planned? You throw around accusations without any basis for them.
Which risk of injury to humans or property damage do you consider acceptable? 1 in a thousand? 1 in a million? 1 in a billion? How does this compare to the risks of Tiangong-1 and Spacelab?

Those who are in love with space at all cost

Do you have an example for this group?

Disposal could be part of any project but that is not a very glamorous phase to plan (at pay) for.

It is part of all projects. But things can fail.

 

[sophiecentaur]

something unexpected went wrong with comms

Skylab entered the atmosphere largely uncontrolled as well.

Comms can be made as fault tolerant as you're prepared to pay for. Both of those craft were built to sustain human passengers so they would both have been built with appropriate ruggedness. But skylab was twenty years earlier and things could / should be better these days.

Do you have an example for this group?

That would involve a personal comment which would not be nice but we all know how the 'space' solution for many problems gets more approval from many members. I appreciate that the Physics of a space project is often more interesting than a boring old Earthbound solution so there is some excuse for that.

I just thought. Why not use space junk as the source of material for the solar sunshade in that other thread?

 

[Laurie K]

On the latest projections (07:11 UTC, April 1) Satview has Tiangong 1 reentering on 2 April at 01:39 UTC and USstratCom has it reentering at 00:15 UTC. Both projections have an altitude of nominal burst of 128km. 15h 23m as I post.

 

[256bits]

Risk. That’s an open term. If the demise of Skylab was as badly planned as that of the Chinese station then my comment applies. If no money can be spared for suitable protective measures then a project should not fly.
Those who are in love with space at all cost should perhaps examine the priorities a bit. We tut tut about all the space junk but it is no surprise that it exists. Disposal could be part of any project but that is not a very glamorous phase to plan (at pay) for.

Does/did either one have a propulsion system capable of a giving the station a controlled deorbit.
probably not,

 

[256bits]

Which risk of injury to humans or property damage do you consider acceptable? 1 in a thousand? 1 in a million? 1 in a billion? How does this compare to the risks of Tiangong-1 and Spacelab?

Around 1 in a trillion for you or me or anyone else to be hit personally by a piece of space junk.
Globally, in the path of reentry, the number of people expected to be hit is 10^-4.

 

[256bits]

http://www.google.ca/url?sa=t&rct=j...ep1&type=pdf&usg=AOvVaw3UerILQ-pGnkKwx2cka0o5

 

[256bits]

It strikes me that wilfully ignoring the possibility of such a disaster in the initial planning of the space station should be treated as a criminal act. The must have been a time in the station's life when it could have been brought down Smith precision and somewhere safe. This is a potential International Incident; it is not a potential act of god.
But some nations have less regard than others for human life.

I think the state responsible for sending something into space is also responsible for damage caused when it comes down.
I don't know if there is a special treaty to that, and/or if everyone needs to sign on.
Nevertheless, a court of arbitration of international law probably comes into effect in these instances determining owner of satellite, damage, cleanup, and compensation for the infringed upon nations or entities.

 

[OmCheeto]

...
I don't know if there is a special treaty to that, and/or if everyone needs to sign on.
...

Apparently there is:

What to do if this Chinese space station crashes into your house this weekend
Mar 30, 2018 5:44 PM EDT

Step 1: Don’t touch anything
Step 2: Call a diplomat

...That means if Tiangong-1 did strike your property, your sole means of recourse would be the Space Liability Convention, an international treaty ratified in 1972 by the United Nations.​

Step 3: Realize that space is a quasi-lawless frontier

...No one was harmed in 1979 when NASA’s 80-ton Skylab made a semi-controlled descent that scattered wreckage across a rural part of northern Australia. Still, the Aussies used the opportunity to play a prank, issuing a $400 ticket for littering to the American space agency.​

 

[OmCheeto]

Also, if you are lucky enough to:

a. not be killed by the falling debris

and​

b. find some debris​

According to international law, it will not belong to you:

Agreement on the Rescue of Astronauts, the Return of Astronauts and the Return of Objects Launched into Outer Space

"...States shall, upon request, provide assistance to launching States in recovering space objects that return to Earth outside the territory of the Launching State."​

Though, I didn't see anything about a "finders fee", which might explain:

Skylab's Grave: Remains of 1st American Space Station in Australia​

 

[Spinnor]

This looks neat,

From, http://www.aerospace.org/cords/reentry-predictions/tiangong-1-reentry/

Looks like it is predicted to skip a bit?

What a good reentry light show looks like,



Could use image stabilization.

 

[Spinnor]

Live blog at, https://www.express.co.uk/news/scie...IVE-expected-to-crash-midnight-tonight-latest

Good video for Monday I hope.

 

[OmCheeto]

...
Looks like it is predicted to skip a bit?
...

If you are referring to the dip then rise in altitude, that's actually because it's in a slightly elliptical orbit.

Here's a snapshot I took a couple of days ago:

2018.03.30 0019 PDT

 

[mfb]

The station passed Japan, so far without re-entry reports. Now it will fly over the Pacific, reaching the predicted central reentry point of aerospace.org shortly before Chile. If it is still around afterwards, it might enter over South America, the South Atlantic, Africa, Asia, or again the Pacific.

It should have passed the Altair tracking station right at the time of my post, so we should have a new estimate soon.

Edit: Not clear if Altair found it - due to drag the orbit is now hard to predict. Now passing over South America, if it is still in space.

Edit2: Unclear if it has been seen over South America (cloudy?), might reenter over the Atlantic.
A lot of rubbish on Twitter.

 

[mfb]

On Twitter there are a few reports that it might have crashed close to Chile, some of them could be real. We'll know more in a few hours.

 

[JLowe]

Several sites report that it crashed in the South Pacific west of Chile.

 

[mfb]

Here is a reliable source.
That's it. Very close to the usual place for planned deorbits.

 

[Laurie K]

Here is a reliable source.
That's it. Very close to the usual place for planned deorbits.

On Satview that was their projected reentry location and it was an April 1 notice. The post from Spinnor #40 has a closer location to the last projection that Satview said was from USstratCom when I made my previous post here. They said USstratCom projected April 2 00:15 UTC and they now have a USstratCom message stating that Tingong 1 had reentered the atmosphere on April 2 at 00:16 UTC +/- 1 minute, on the link below.

http://www.satview.org/?sat_id=37820U

Also it looks like the Chinese engineered Tiangong 1 to glide in if they lost control, from the German radar pics (link below) on March 1, Congratulations guys.

https://www.space.com/40089-china-space-station-tiangong-1-radar-images.html