Updates Tiangong 1 reentry

[cristiapi]

Hi Cris, i can perform a reentry simulation for the tiangong using orbiter, or better i can try to simulate approaching some info and coefficients,just give me some time to do it.

Hi infotechggs, very good!
Do you plan to use an improved atmospheric model with updated solar indices?

Just for curiosity,which type of software did you use to plot the space weather on this picture?

I just use excel to plot the solar indices given in this file:
ftp://ftp.agi.com/pub/DynamicEarthData/SpaceWeather-All-v1.2.txt

 

[cristiapi]

Here is a Monte Carlo simulation for the reentry date:

For each TLE, I calculate the initial state of the Tiangong-1 for the TLE epoch with the SGP4 propagator, then I propagate it with a specially crafted propagator (based on a DOPRI853 integrator).
Then, for 49 times I add a random offset to the initial radius vector and I propagate the new random state (the gray diamonds in the graph).
I obtained 50 reentry dates for each TLE. The graph shows 64 blue diamonds (the number of the used TLE) and 3136 gray diamonds (the modified initial states).
The simulation took about 12 hours of CPU time (I ran 2 simulations simultaneously).

 

[GLS]

Watched it at dusk (finally ) a few times this week... the 280Km altitude shows as it zooms by faster than e.g. the ISS.

---------- Post added at 01:14 AM ---------- Previous post was at 01:04 AM ----------

Any predictions on the groundtracks for that 2 week period, or is it still too "spread" to mean anything?

 

[cristiapi]

Here is the predicted reentry locations that come from the same Monte Carlo simulation:

a perfect random number generator!

 

[GLS]

Here is the predicted reentry locations that come from the same Monte Carlo simulation:

a perfect random number generator!

Yeah, still too much uncertainty, although the blue dots seem to be +/- over South America, Europe and Asia... :shifty:

---------- Post added at 11:59 AM ---------- Previous post was at 11:19 AM ----------

Here's the plot above overlaid on a map:

(blue dots replaced with red dots to have more contrast with blue oceans)

 

[cristiapi]

Very nice! Thank you.
There is a red dot almost above my head!

EDIT:
If you like to play with the data, you can download the excel file:
http://cristianopi.altervista.org/Tiangong/TIA1-2018-01-20_MC_XLS.7z

 

[Andy44]

We should start a contest: if it hits your car or your house, all of OF buys you a beer, one from each of us.

 

[cristiapi]

My latitude is 43.5 N, while the Tiangong-1 inclination is only 42.8; I'm safe! But if you want to send me 100 lt of Guinness, I'll be very happy! :lol:

 

[Notebook]

A new unit of inclination, Guiness per Degree. I think I've been there...

N.

 

[Thunder Chicken]

I wonder if you took the data and made a histogram by latitude, maybe you would see a higher probability at the extremes of latitude?

 

[Andy44]

I wonder if you took the data and made a histogram by latitude, maybe you would see a higher probability at the extremes of latitude?

I was thinking the same thing.

 

[Urwumpe]

We should start a contest: if it hits your car or your house, all of OF buys you a beer, one from each of us.

And if an orbiteer is hit, we'll drink a toast to him?

Like "He was really a great lad, but he did not know when it was time to step aside."

 

[MaverickSawyer]

And if an orbiteer is hit, we'll drink a toast to him?

Like "He was really a great lad, but he did not know when it was time to step aside."

"hey, guys, I'm gonna catch a piece of the-"
WHAM

:lol:

 

[cristiapi]

I wonder if you took the data and made a histogram by latitude, maybe you would see a higher probability at the extremes of latitude?

The map shows 2 Tiangon-1 orbits (Miller Cylindrical projection):

This one shows 40 orbits:

Does that answer the question?

 

[GLS]

I wonder if you took the data and made a histogram by latitude, maybe you would see a higher probability at the extremes of latitude?

If you look at the orbit projected on a map you'll see that it "hangs around" the high end of the latitudes more than equatorial regions, where it quickly "passes by". So, excluding all other factors and assuming an uniform distribution around the orbit for the probability of impact, you should get that "higher probability at the extremes of latitude".

 

[Urwumpe]

Also, the big issue is, that right now, quite many orbits have a similar probability to be the final one. Its hard to get a heat map of possible impact locations at this stage.

 

[Thunder Chicken]

Also, the big issue is, that right now, quite many orbits have a similar probability to be the final one. Its hard to get a heat map of possible impact locations at this stage.

No, you can make a heat map, but it simply won't have much variation in longitude.

 

[Urwumpe]

No, you can make a heat map, but it simply won't have much variation in longitude.

It would also be a pretty flat heatmap - even in latitude, the chances are not too much higher - just see the "dot" map above -> while the extreme altitudes have a few dots more appearing, its mostly a pretty even distribution of the impact locations.

I can give it maybe a try later to create one, I have still R and R Studio installed on my notebook for university work and there is a nice tutorial about it:

https://www.r-bloggers.com/maps-in-r-choropleth-maps/

 

[Andy44]

And if an orbiteer is hit, we'll drink a toast to him?

Like "He was really a great lad, but he did not know when it was time to step aside."

If I get hit with falling space junk I would certainly hope to be remembered on OF. I doubt any of you would know it was me, though. You'd see my real name in the news but probably nobody would connect it to my user name...I would be an unsung lost Orbinaut.

 

[Urwumpe]

If I get hit with falling space junk I would certainly hope to be remembered on OF. I doubt any of you would know it was me, though. You'd see my real name in the news but probably nobody would connect it to my user name...I would be an unsung lost Orbinaut.

Maybe we should get some robust ceramic card to put into our wallets "Wanderer, should I get killed by space debris, go tell the Orbiter-Forum, I was trying my best to catch it first." :lol: