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#340
by
saliva_sweet
on 28 Oct, 2017 11:09
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Anyone have any idea what just happened to the R/B from this launch? Did they perform a de-orbit manoever???
1 42802U 17038B 17293.72551647 .00027554 34224-5 23039-2 0 9996
2 42802 24.5026 10.7656 8296019 214.1455 24.5398 1.15434098 1332
1 42802U 17038B 17298.50320531 -.00000191 22902-6 00000+0 0 9993
2 42802 24.2449 8.5033 5926106 217.8158 334.7218 4.30932446 1399
1 42802U 17038B 17298.50320531 -.00000191 22902-6 00000+0 0 9993
2 42802 24.2449 8.5033 5926106 217.8158 334.7218 4.30932446 1399
1 42802U 17038B 17298.50320531 -.00000191 22902-6 00000+0 0 9993
2 42802 24.2449 8.5033 5926106 217.8158 334.7218 4.30932446 1399
1 42802U 17038B 17298.50320531 -.00000191 22902-6 00000+0 0 9993
2 42802 24.2449 8.5033 5926106 217.8158 334.7218 4.30932446 1399
1 42802U 17038B 17299.50658123 .00002909 -18328-4 00000+0 0 9999
2 42802 24.1857 6.6360 2957658 221.3868 298.2410 9.85103635 1432
Why do all the TLEs have the same set number?
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#341
by
Notleslie
on 28 Oct, 2017 11:10
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I got them from Space-track.org
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#342
by
saliva_sweet
on 28 Oct, 2017 11:17
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I guess it's the same observation being refined over time. All except the last TLE are bugged. But I'm not sure.
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#343
by
Raul
on 28 Oct, 2017 23:09
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Anyone have any idea what just happened to the R/B from this launch? Did they perform a de-orbit manoever???
No de-orbit maneuver, this is standard gradual deceleration of the second stage before reentry and decay from GTO due to drag in upper atmosphere at perigee 154, 120 and 95 km.
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#344
by
Comga
on 29 Oct, 2017 03:40
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Can someone translate those TLEs into date, apogee, and prrigee?
The decay of second stages left in GTO orbits has been of interest for a long time.
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#345
by
Raul
on 29 Oct, 2017 08:17
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Can someone translate those TLEs into date, apogee, and prrigee?
Fri Oct 20 2017 17:24:44 GMT 154/63757km
Wed Oct 25 2017 12:04:36 GMT 120/19026km
Thu Oct 26 2017 12:09:28 GMT 95/5533km
Fri Oct 27 2017 Decayed
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#346
by
saliva_sweet
on 29 Oct, 2017 09:07
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Fri Oct 20 2017 17:24:44 GMT 154/63757km
Wed Oct 25 2017 12:04:36 GMT 120/19026km
Thu Oct 26 2017 12:09:28 GMT 95/5533km
Fri Oct 27 2017 Decayed
So they were separate TLEs. Can you explain why they had the same set number - 999 (first three digits of the last element of line 1)? I thought these were supposed to be incremented each time a new TLE set was created.
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#347
by
Notleslie
on 29 Oct, 2017 09:08
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Fri Oct 20 2017 17:24:44 GMT 154/63757km
Wed Oct 25 2017 12:04:36 GMT 120/19026km
Thu Oct 26 2017 12:09:28 GMT 95/5533km
Fri Oct 27 2017 Decayed
So they were separate TLEs. Can you explain why they had the same set number - 999 (first three digits of the last element of line 1)? I thought these were supposed to be incremented each time a new TLE set was created.
They are but I got them from Space-track.org where they are all 999 for some reason
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#348
by
saliva_sweet
on 29 Oct, 2017 09:20
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They are but I got them from Space-track.org where they are all 999 for some reason
Space-track sets all set numbers in all TLEs for all objects to 999?
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#349
by
Notleslie
on 29 Oct, 2017 09:22
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They are but I got them from Space-track.org where they are all 999 for some reason
Space-track sets all set numbers in all TLEs for all objects to 999?
On my account they seem too, I assumed it was the same for everyone.
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#350
by
Comga
on 31 Oct, 2017 15:44
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Can someone translate those TLEs into date, apogee, and prrigee?
Fri Oct 20 2017 17:24:44 GMT 154/63757km
Wed Oct 25 2017 12:04:36 GMT 120/19026km
Thu Oct 26 2017 12:09:28 GMT 95/5533km
Fri Oct 27 2017 Decayed
Adding in the initial orbital elements from the Update thread and plotting:
It looks like the second stage hit a brick wall in late October.
Possibly had the perigee tidally pulled lower and it snowballed.
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#351
by
woods170
on 31 Oct, 2017 17:51
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Can someone translate those TLEs into date, apogee, and prrigee?
Fri Oct 20 2017 17:24:44 GMT 154/63757km
Wed Oct 25 2017 12:04:36 GMT 120/19026km
Thu Oct 26 2017 12:09:28 GMT 95/5533km
Fri Oct 27 2017 Decayed
Adding in the initial orbital elements from the Update thread and plotting:
It looks like the second stage hit a brick wall in late October.
Possibly had the perigee tidally pulled lower and it snowballed.
That brick wall is known as Earth's atmosphere.
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#352
by
Lar
on 31 Oct, 2017 18:38
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There isn't a step change in density, it's more gradual (leading to expectations of a less steep decay curve) but the effect might as well be a brick wall I guess?
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#353
by
Comga
on 31 Oct, 2017 18:56
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Can someone translate those TLEs into date, apogee, and prrigee?
Fri Oct 20 2017 17:24:44 GMT 154/63757km
Wed Oct 25 2017 12:04:36 GMT 120/19026km
Thu Oct 26 2017 12:09:28 GMT 95/5533km
Fri Oct 27 2017 Decayed
Adding in the initial orbital elements from the Update thread and plotting:
It looks like the second stage hit a brick wall in late October.
Possibly had the perigee tidally pulled lower and it snowballed.
That brick wall is known as Earth's atmosphere.
As Lar said, the atmosphere is not a brick wall.
Look at something like
the orbital decay of Tiangong 1. It spent all of October in the atmosphere below 310 km without falling out of the sky. The decay does, however, get steeper all the time.
The Bulgariasat second stage spent four months dipping below 200 km on each orbit.
Then something passed a threshold, either a tipping point in atmospheric density or an external event, like a gravitational tug from the Moon.
A salient question is what was that event, and what does it say about the decay of other second stages. But that's for another thread.
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#354
by
Lars-J
on 31 Oct, 2017 19:46
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Can someone translate those TLEs into date, apogee, and prrigee?
Fri Oct 20 2017 17:24:44 GMT 154/63757km
Wed Oct 25 2017 12:04:36 GMT 120/19026km
Thu Oct 26 2017 12:09:28 GMT 95/5533km
Fri Oct 27 2017 Decayed
Adding in the initial orbital elements from the Update thread and plotting:
It looks like the second stage hit a brick wall in late October.
Possibly had the perigee tidally pulled lower and it snowballed.
That brick wall is known as Earth's atmosphere.
As Lar said, the atmosphere is not a brick wall.
Look at something like the orbital decay of Tiangong 1. It spent all of October in the atmosphere below 310 km without falling out of the sky. The decay does, however, get steeper all the time.
The Bulgariasat second stage spent four months dipping below 200 km on each orbit.
Then something passed a threshold, either a tipping point in atmospheric density or an external event, like a gravitational tug from the Moon.
A salient question is what was that event, and what does it say about the decay of other second stages. But that's for another thread.
A circular LEO orbital decay is going to be a lot more gradual and predictable.
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#355
by
envy887
on 31 Oct, 2017 19:54
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The Bulgariasat second stage spent four months dipping below 200 km on each orbit.
Then something passed a threshold, either a tipping point in atmospheric density or an external event, like a gravitational tug from the Moon.
A salient question is what was that event, and what does it say about the decay of other second stages. But that's for another thread.
There are several exponentially compounding effects here. Air density and thus drag at 95 km is some 100x higher than at 154 km. Also, as each perigee pass slows the stage, the apogee drops significantly - and since most of the orbit time is around apogee, the next perigee pass happens much sooner.
154/63757km has a period of 20.7 hours
120/19026km has a period of 5.8 hours
95/5533km has a period of 2.48 hours
So even though that last orbit doesn't look substantially lower, it's decaying ~1000x faster than the highest orbit.
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#356
by
Comga
on 31 Oct, 2017 21:22
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All that is known.
The atmosphere doubles in density roughly every 20 km
Lowering the perigee reduces the orbital period resulting in more passes through the top of atmosphere per day.
The emptied second stage is particularly light and large, almost a giant aluminum balloon.
Nevertheless, the terminal decay is rather dramatic.
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#357
by
envy887
on 01 Nov, 2017 01:18
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All that is known.
The atmosphere doubles in density roughly every 20 km
Lowering the perigee reduces the orbital period resulting in more passes through the top of atmosphere per day.
The emptied second stage is particularly light and large, almost a giant aluminum balloon.
Nevertheless, the terminal decay is rather dramatic.
Density doubling every 20 km is not accurate in this perigee range. Around 120 km there is a "knee" in the curve and density increases more than 100-fold in just 25 km. This makes decay extremely sensitive to perigee altitude.
The plots below model air density from 95 to 155 km; one is on a log scale, the other the same data on a linear scale:
Data from:
https://omniweb.gsfc.nasa.gov/vitmo/msis_vitmo.html
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#358
by
Comga
on 01 Nov, 2017 01:42
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Neat data
The log-linear assymptotes show that above 130 km the doubling height is ~13 km
Below 110 km it's only ~3 km
That is a lot like a brick wall.
Doubling every 20 km is a decent approximation above 300 km
Near the ground, it doubles around 20 kft or 6 km.
SO nonlinear.
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#359
by
Notleslie
on 02 Nov, 2017 05:33
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Theres a new elset on Space-track.org for it... what the heck is going on with their elsets??
1 42802U 17038B 17305.79196749 +.99999999 -28699-4 +93816-8 0 9999
2 42802 024.1564 357.8001 2618557 238.2422 285.5175 10.75890139002054