Updates Tiangong 1 reentry

[GLS]

I'm sure some people now breathing better, other probably not...

It the date still around April 10?

 

[cristiapi]

No, now is predicted for March 2:

Before March 12, the reentry was on April 5 (see post #54), but from March 11 to March 13 something strange happened:

notice the big burst on the decay rate (I'm not totally convinced that the Tiangong-1 is completely out of control).

 

[GLS]

Yes, April 5... (for some reason I had the 10th in my mind :S)

About the "anomaly": I searched for solar activity around that time and only around March 15 did "stuff happen", so it shouldn't be that.
For the "control" hypothesis, could the timeframe of those "blips" be correlated with it flying over China? If it is indeed being commanded it makes sense it would be directly from the ground (and not from a communications ship... at least for now). It would have to have a pass between the last normal rate and the first higher rate measurements, and another pass when it returned to the usual.

 

[cristiapi]

China is very wide and the station passes many times over it. Here is one of the March 11 passes:

 

[Urwumpe]

Another factor could be that the axis of tumbling changed. AFAIR, the station was never designed to be spin stabilized, so a sudden transfer of rotational impulse from one vector component to the other should be possible.

EDIT: But looking at the plot for a longer period of time, the change does not look too impressive in the past days.

http://www.satflare.com/track.asp?q=37820#TOP

It rather looks like it is in a pretty expected exponential curve down.

 

[cristiapi]

Another factor could be that the axis of tumbling changed.

That can be checked with the B* TLE parameter (TLE line 1, columns 54 to 61):

We can see an almost periodic shape for B* that probably shows a slow chaotic tumbling (we can also see the big peak that perfectly matches the peak in the decay rate).

 

[Urwumpe]

The Fraunhofer Institute for High Frequency Physics and Radar Techniques (FHR) have produced some bistatic radar images of the station:

https://www.fhr.fraunhofer.de/de/presse-medien/pressemitteilungen/wiedereintritt_tiangong-1.html

Like in similar missions in the past, they used the 34m TIRA radar antenna in near Bonn together with the 100m dish at Effelsberg to produce the images.

 

[Notebook]

http://www.esa.int/spaceinimages/Images/2018/03/Spotted_in_space

Title Spotted in space
Released 28/03/2018 10:33 am
Copyright Fraunhofer FHR. Used by permission
Description
In the next few days, an unoccupied Chinese space station, Tiangong-1, is expected to reenter the atmosphere following the end of its operational life. Most of the craft should burn up.
ESA is hosting a campaign to follow the reentry, conducted by the Inter Agency Space Debris Coordination Committee (IADC).

 

[RacerX]

does anybody know of a place where there will be a live stream of the event? Or is that impossible to do at this point?

 

[Urwumpe]

does anybody know of a place where there will be a live stream of the event? Or is that impossible to do at this point?

Well, if you know where it will come down, you could place a camera there. But right now, its a bit hard to even tell exactly WHEN it will happen. :lol:

http://blogs.esa.int/rocketscience/2018/03/26/tiangong-1-reentry-updates/

Right now, the window runs from noon (UTC) on the March 31st to early afternoon (UTC) on the first April.

 

[GLS]

(image is updated +/- every 5 minutes)
http://www.aerospace.org/cords/reentry-predictions/tiangong-1-reentry/

 

[Notebook]

BBC article:

http://www.bbc.co.uk/news/science-environment-43557446

N.

 

[Zatnikitelman]

I live in Atlanta, I guess I need to wear a hard hat Saturday through Sunday.

 

[GLS]

(image is updated +/- every 5 minutes)
http://www.aerospace.org/cords/reentry-predictions/tiangong-1-reentry/

Right now it looks like it will miss Europe and Africa, leaving SE Asia and the Americas in the firing line.

 

[MaverickSawyer]

Current projected time puts it somewhere near the Philippines and Indonesia...

 

[GLS]

Latest forecast has Africa and SE Europe coming into the firing line, as well as Central Asia and the ME, while North and Central America have become safer. The reentry time is still showing a "delaying" trend, so I expect the actual reentry time to move further forward, which would increase the risk in Europe. :shifty:

---------- Post added 04-01-18 at 02:29 AM ---------- Previous post was 03-31-18 at 04:00 PM ----------

Looks like the will to live is strong with this one, as it will survive another day. The predictions are now pointing to a middle of the night reentry (UTC) on the 2nd, which puts it pretty much in the worst groundtrack IMO, with only North America being safe.

 

[Zatnikitelman]

Surprised no one's ASAT'd it yet.

 

[MaverickSawyer]

Well, the Chinese would be the only ones able to do so without causing a major international incident... And they've already proven that they can hit smaller and higher targets. So burning an ASAT missile would be rather pointless.

 

[GLS]

New update: 5h window around 0010UTC April 2nd.

Africa, South America and Asia in the firing line.

 

[Notebook]

http://www.bbc.co.uk/news/science-environment-43557446

The estimated window of re-entry for the defunct Chinese space lab Tiangong-1 has narrowed sharply.
The timeframe for the fall to Earth is centred on 01:07 Monday GMT (02:07 BST), plus or minus two hours.
Experts are tracking the module as it orbits at an ever decreasing altitude.
However, they will only be sure of the timing of the final plunge very late in the descent because of the uncertainties over Tiangong's interactions with the high atmosphere.

Only a "plunge", not a "Death Plunge". Must be optimistic.

N.