Author Topic: LIVE: TianGong-1 JSLC CZ-2F (T1) launch September 29, 2011  (Read 341602 times)

Offline titusou

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Re: LIVE: TianGong-1 JSLC CZ-2F (T1) launch September 29, 2011
« Reply #800 on: 09/07/2017 10:20 PM »
It looks like orbit decay been accelerated a bit in last few wks...
lmage from heavens above.

Titus
« Last Edit: 09/07/2017 10:21 PM by titusou »

Offline Thomas Dorman

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Re: LIVE: TianGong-1 JSLC CZ-2F (T1) launch September 29, 2011
« Reply #801 on: 09/08/2017 07:23 PM »
titusou
Do not believe we are seeing anything unusual it is what  would be pretty much expected as Tiangong 1 interacts with the Earth tenuous upper Atmosphere causing more drag on the Space Station. With the significant increase in Solar activity over the last month would not be surprise to see this increase in decay become a little steeper.  Even if it was losing 30 Kilometers a month you still are looking at a decay some where in the mid- January to mid February of 2018. We do have several high passes in the next  few week will once again take a look to monitor for signs of the space station starting to tumble.
Regards
Thomas
« Last Edit: 09/08/2017 07:24 PM by Thomas Dorman »

Offline Star One

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LIVE: TianGong-1 JSLC CZ-2F (T1) launch September 29, 2011
« Reply #802 on: 09/08/2017 07:51 PM »
titusou
Do not believe we are seeing anything unusual it is what  would be pretty much expected as Tiangong 1 interacts with the Earth tenuous upper Atmosphere causing more drag on the Space Station. With the significant increase in Solar activity over the last month would not be surprise to see this increase in decay become a little steeper.  Even if it was losing 30 Kilometers a month you still are looking at a decay some where in the mid- January to mid February of 2018. We do have several high passes in the next  few week will once again take a look to monitor for signs of the space station starting to tumble.
Regards
Thomas

I think with the level of solar activity your prediction could be seen as something of a hostage of fortune.
« Last Edit: 09/10/2017 06:37 PM by Star One »

Offline Thomas Dorman

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Re: LIVE: TianGong-1 JSLC CZ-2F (T1) launch September 29, 2011
« Reply #803 on: 09/08/2017 11:31 PM »
Star One
Look at the graph you are looking at best a 6 Kilometer drop since the middle of August. We were projecting on a 30 Kilometer drop every month out to next year. We are still looking at a  reentry time next year some where in the first three months 2018. One exception here to the prediction is if Tiangong 1  starts to tumble then we have a whole new ball game that is why we are doing as many observation of high passes of Tiangong 1 looking to see if it starts to go into a tumble!  Also Solar active is going to have to kick into high gear over the next five month to change this drastically which we are now in a declining Solar cycle. Just because we see a little increase in Solar activity doesn't mean we will see this continue for five or six months down the road.
Regards
Thomas
« Last Edit: 09/08/2017 11:32 PM by Thomas Dorman »

Offline Star One

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Re: LIVE: TianGong-1 JSLC CZ-2F (T1) launch September 29, 2011
« Reply #804 on: 09/08/2017 11:49 PM »
Star One
Look at the graph you are looking at best a 6 Kilometer drop since the middle of August. We were projecting on a 30 Kilometer drop every month out to next year. We are still looking at a  reentry time next year some where in the first three months 2018. One exception here to the prediction is if Tiangong 1  starts to tumble then we have a whole new ball game that is why we are doing as many observation of high passes of Tiangong 1 looking to see if it starts to go into a tumble!  Also Solar active is going to have to kick into high gear over the next five month to change this drastically which we are now in a declining Solar cycle. Just because we see a little increase in Solar activity doesn't mean we will see this continue for five or six months down the road.
Regards
Thomas

To play devils advocate it also doesn't mean that we will not see this greater activity continue. The problem with all these cycles we impose on the Sun is we just haven't been studying it long enough to see the longer cycles. I've seen this argued by those far wiser in such things than me.

Online Phillip Clark

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Re: LIVE: TianGong-1 JSLC CZ-2F (T1) launch September 29, 2011
« Reply #805 on: 09/09/2017 01:30 AM »
Even specialists in the field of estimating orbital decays admit that it is more of an art than an exact science!

Offline Thomas Dorman

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Re: LIVE: TianGong-1 JSLC CZ-2F (T1) launch September 29, 2011
« Reply #806 on: 09/09/2017 02:03 AM »
Let's throw another fly in the ointment! The 22 year solar magnetic cycle and the effects on Earth's atmosphere.
http://iopscience.iop.org/article/10.1088/0004-6256/144/1/6
Rarely do you hear any one talk about this cycle and it's effects.
Still been observing and tracking satellites for five decades, our first satellite being Echo II, if we are wrong on our prediction will be more than willing to eat our whole heaping helping of cold crow  barring as we have caveat that we do not see Tiangong -1 start tumbling and it remains in a roll until reentry interface.
Regards
Thomas

Offline titusou

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Re: LIVE: TianGong-1 JSLC CZ-2F (T1) launch September 29, 2011
« Reply #807 on: 09/10/2017 09:14 AM »
I tried to overlay 37820 (shallow line) meaning height over to 41477 (steep line). Attached image is what I got.

37820 = Tiangong1, image is compress vertically to get the same meaning height grid with 41477
41477 = Nodes2 cubesat launch from ISS (somehow but Heavns-Above.com wrote it as Nodes1)

I know there are alot of variables will affect orbit decay, but a simple comparison:

360->340km: 41477 = 2.1mons; 37280 = 4.8mons
340->320km: 41477 = 2.0mons; 37280 = 4.2mons

I guess that's indication of 37820's BC is ~2.2 times of 41477.

For 41477, 320->260km is 2.2mons

If everything goes liner, it will take 37820 4~5mons to reach 260km, which place the timing to mid-Jan~mid-Feb,2018.

I'm really curious to see how accurate that goes.


Titus

--
(edited for typo fix)
« Last Edit: 09/10/2017 09:16 AM by titusou »

Online Phillip Clark

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Re: LIVE: TianGong-1 JSLC CZ-2F (T1) launch September 29, 2011
« Reply #808 on: 09/10/2017 09:35 AM »
When I presented my Tiangong 1 paper at the Sino-Russian Technical Forum of the British Interplanetary Society on May 21, 2016 I gave "rough estimate for decay: second quarter of 2018".

Offline titusou

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Re: LIVE: TianGong-1 JSLC CZ-2F (T1) launch September 29, 2011
« Reply #809 on: 09/10/2017 01:59 PM »
When I presented my Tiangong 1 paper at the Sino-Russian Technical Forum of the British Interplanetary Society on May 21, 2016 I gave "rough estimate for decay: second quarter of 2018".
In my world the first question after that would be... FY or CY? ;ppp

But seriously, do you see current behavior fit to your prediction?

Titus

Online Phillip Clark

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Re: LIVE: TianGong-1 JSLC CZ-2F (T1) launch September 29, 2011
« Reply #810 on: 09/10/2017 04:20 PM »
When I presented my Tiangong 1 paper at the Sino-Russian Technical Forum of the British Interplanetary Society on May 21, 2016 I gave "rough estimate for decay: second quarter of 2018".
In my world the first question after that would be... FY or CY? ;ppp
But seriously, do you see current behavior fit to your prediction?
Titus

I simply averaged out the short-term irregularities and used a "best fit" curve based upon the decay rate from December 2015 (the last manoeuvre) to May 2016.

Offline titusou

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Re: LIVE: TianGong-1 JSLC CZ-2F (T1) launch September 29, 2011
« Reply #811 on: 09/10/2017 11:41 PM »
Found something interesting to read, not directly related to Tiangong1, but about Skylab deorbit story.
http://www.spaceref.com/iss/skylab.deorbit.html

Titus

Offline Thomas Dorman

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Re: LIVE: TianGong-1 JSLC CZ-2F (T1) launch September 29, 2011
« Reply #812 on: 09/14/2017 07:24 PM »
This morning pass of Tiangong 1  at 10:28 UT September 14,2017 on a max pass of 86 degrees. Three video clips shot between  70 degrees to  around 30 degrees elevation with phase angles ranging  from 58 degrees to 134 degrees. Distances ranged from 334.4 Kms  to around 590.9 Kms. Also observed it visually Tiangong 1 shows zero signs of any tumble.

Regards
Thomas

Offline Thomas Dorman

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Re: LIVE: TianGong-1 JSLC CZ-2F (T1) launch September 29, 2011
« Reply #813 on: 09/18/2017 05:39 PM »
http://www.newsweek.com/china-tiangong-1-out-control-space-station-crash-earth-2018-666836?utm_source=yahoo&utm_medium=yahoo_news&utm_campaign=rss&utm_content=/rss/yahoous/news&yptr=yahoo
The prediction made by Aerospace Corporation in this article is pretty much the prediction some of us in the Amateur satellite observing community made back in early 2016 to the window of reentry! Once again unless we see Tiangong 1 start to tumble this window for reentry still stands.
Let get's some facts straight Tiangong 1 doesn't orbit over 2/3 of the Earth Ocean it goes no more than 42 degrees North or South of the Equator. This leaves 48 degrees North or South of the Equator the Space Station never passes over.
Yep, its orbit does take it over some of the most populated areas on the planet.
So we are going to pony up now with our prediction of odds of damage or casualties on the ground. Believe the odds come down to if the space station is still in a roll or what degree of tumble the space station has at reentry. So going to give a range at 1 in 2600 to a 1 in 3100 chances of damage or casualties on the ground.

Now some of the numbers on the amount of debris making it to the ground, given by some experts, have ranged in 40 to 80 pounds ranging up to 200 to 300 pounds. We believe, we know we are going to take a beating on this one, that the debris will be in an order of a little less than 1 metric ton or somewhere near or around 2000 pounds.
Let the games begin with the media and the "Experts"! ;D ;) :)
Regards
Thomas

Offline titusou

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Re: LIVE: TianGong-1 JSLC CZ-2F (T1) launch September 29, 2011
« Reply #814 on: 09/25/2017 02:58 PM »
Nodes2 (41477) is now deorbited, so it give a pretty good background info to compare with Tiangong1 (37820).
I will try to keep this up-to-date monthly update so we have better comparison.

Titus

Tags: TianGong-1