Dr Marco Langbroek Profile picture
Aug 4, 2021 10 tweets 9 min read Read on X
The #Proton-M third stage from the #Nauka launch is now coming down faster and faster.
Current prediction models place reentry within 2 days from now, either late August 5 or early August 6, with the trend in predictions tending towards August 5.
@SSC_NL ImageImage
These reentry forecasts are also on my blog:
sattrackcam.blogspot.com/2021/08/proton…
The #Proton-M third stage from the #Nauka launch now has less than one day left in orbit. Current model forecasts suggest a reentry in the morning of August 6 UT. ImageImage
New update. The #Proton-M rocket stage is going down faster and faster. Last published orbit (12:14 UT) has it in a 178 x 146 km orbit
My nominal current GMAT reentry result is 6 Aug 2:56 +- 3h UT, but looking at the trend it will probably be a bit earlier. ImageImage
New orbit released, pushing #reentry of the #Proton-M 3rd stage from the #Nauka launch slightly back: my current modelled reentry is at 5:07 +- 2.5 h UT (6 Aug). This window encompasses about 4 revolutions around earth.
Current CSpOC TIP is 4:27 +- 2h UT ImageImage
This is the approximate trajectory over the time window for the #Proton rocket stage #reentry given in the previous tweet.
Yellow circle is the nominal GMAT position, grey the current CSpOC TIP.
Note that both are still quite meaningless as the uncertainty is multiple revolutions Image
New update for the #Proton-M 3rd stage #reentry: my GMAT modelling suggests reentry at 5:34 +- 1.7h UT, 6 Aug.
HOWEVER, I have my doubts about the last 3 orbit updates, as the perigee suddenly is (too) stable at 145 km. So I suspect we'll acctually see reentry earlier. ImageImage
Overnight a new orbit for the #Proton-M 3rd stage with almost the same epoch as previous one was published: confirms the last few orbits are unreliable.
My GMAT modelled #reentry time based on this orbit: 4:49 +- 1.6h UT.
So it is down, have to wait for the final TIP for where. ImageImage
The #Proton-M 3rd stage should have come down last night somewhere on the line in the map below. Nominal predicted positions are shown but quite meaningless with a ~1.6 hr (= two full orbital revolutions) uncertainty.
Perhaps a new TIP later today might shed some more light. Image
The final CSpOC #TIP for the #reentry of the #Proton-M upper stage from the Nauka launch today is in:
4.46 +/- 1m UT at 37.8 N 155.7 W.
Turns out my last nominal GMAT estimate (4:49 UT) was very close!!!
(in all honesty: given the uncertainty margins, this is pure luck...) Image

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More from @Marco_Langbroek

Nov 18, 2023
So, I did some simulations with GMAT.
Assumptions:
- For totally arbitrary drag area of 1 m^2;
- Near-orbital speed at disintegration;
- disintegration at 148 km;
labels are mass in kg of fragment.
@planet4589 @DJSnM @Ian_Benecken Image
2/x
additional info: no mass loss due to ablation upon reentry (this is important: if they do loose mass 9and they will), they come down earlier than in the map)
3/x
Nevertheless: they appear to be surviving a lot further downrange than I actually had anticipated.
Read 7 tweets
Oct 25, 2023
1/x
The very successful @AETUDelft-built 3U cubesat Delfi-C3, launched 15 yrs ago, is near the end of its life. It will probably reenter into the atmosphere next month.
Yesterday evening, I managed to image it with my tracking camera from Leiden, the Netherlands: Image
2/x
Here is the video footage (it is very faint, being a 3U cubesat, i.e. 10 x 10 x 30 cm large). Footage was shot at 25 fps with a WATEC 902H2 Supreme and Samyang 2.0/135 mm lens.
3/x
Over the past months, the cubesat has been coming down increasingly fast. Currently it is in a 351 x 365 km orbit (when launched in 2008, it was at 615 x 635 km) Image
Read 8 tweets
Feb 18, 2023
Approximate trajectory flown by the #ICBM that #NorthKorea tested today. A highly lofted trajectory.
(reconstruction based on Japanese DoD info).

When launched on a 'normal', non-lofted trajectory, the range would be 18000+ km, i.e. capable of reaching any place on Earth
Trajectory is based on rough information on apogee, range, and map with approximate impact point provided by Japanese DoD here:
mod.go.jp/j/press/news/2…
It will be interesting to see what missile it concerns when Northg Korea publishes their propaganda photo's. Hwasong-17? Something new?
Read 9 tweets
Aug 1, 2022
Rumour has it that thisd might be another inspector satellite.
The orbital plane of USA 326 passes over Plesetsk at 20:25 UT
USA 326 (2022-009A) was launched on February 2 this year and is believed to be a new generation of electro-optical reconnaissance satellite:
sattrackcam.blogspot.com/2022/02/the-up…
It is in a 97.4 deg inclined, 518 x 488 km orbit.
The Russian launch today was indeed at 20:25 UTC, right at the moment the USA 326 orbital plane passed over Plesetsk (i.e. the launch was into the orbital plane of USA 326):
interfax.ru/russia/854824
Read 6 tweets
Feb 26, 2022
1/x
Navigational Warnings have appeared that suggest a #test launch of a #Minuteman #ICBM from Vandenberg on March 3 - 4.

(I suspect 1 or 2 more NavWarnings to appear for areas around Kwajalein, based on previous tests)
@nukestrat @mhanham @wslafoy @ArmsControlWonk ImageImage
2/x
To be clear (as such suggestions always arrise):
This has *nothing* to do with the Ukraine crisis. Tests like these are scheduled months in advance.
They are regular tests to ascertain the readiness and training of missile crews.
3/x
As I expected, another Navigational Warning has appeared, adding an extra hazard area west of Kwajalein.
Updated map for this upcoming #Minuteman III test (probably GT240GM): ImageImage
Read 8 tweets
Oct 17, 2021
1/x
(lange) draad:
Het gaat véél verder dan een "hypersonische raket": de Fin. Times claimt dat de Chinese test een test voor FOBS betrof...

FOBS staat voor "Fractional Orbital Bormbardment System". FOBS lanceer je niet op een ballistisch traject zoals een normale ICBM, (cont.)
2/x
...maar worden echt in een baan om de aarde gebracht, zoals een satelliet. Waarna op een gegeven moment met een deorbit burn door een retroraket, de lading weer omlaag wordt gebracht, boven het doelwit.
Welnu: waarom zou je dit zo doen in plaats van een normale ICBM lanceren?
3/x
Het voordeel van FOBS is dat het je toestaat toe te slaan vanuit richtingen die met gewone ICBM's niet worden verwacht. Via een traject over de zuidpool bijvoorbeeld. Dan benader je de VS (het doelwit) vanuit het zuiden (gele lijn), terwijl
Read 26 tweets

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