Proton-M rb (2021-066B) reentry forecast (updated)

 (this post is updated when I have run new predictions)

click diagram to enlarge

The Proton-M third stage from the July 21 Nauka launch (see previous post) is coming down fast. The current reentry forecast models place the reentry into the atmosphere in the early hours of August 6 UT.

The diagram above shows CSpOC TIP data in red, and my own GMAT model results in black. My GMAT predictions in tabular form:

DATE         UT    +-        LAT    LON    orbit epoch
6-8-2021     9:55  1.8  day                28-7-2021 12:12
6-8-2021    16:51  1.7  day                29-7-2021 06:01
6-8-2021     9:18  1.4  day                30-7-2021 04:16
6-8-2021     8:29  1.2  day                31-7-2021 05:28
6-8-2021     9:47  1.0  day                 1-8-2021 05:09
6-8-2021    18:23   23  hr                  1-8-2021 22:54
6-8-2021    21:00   23  hr                  2-8-2021 03:19
6-8-2021    13:52   17  hr                  3-8-2021 00:31
6-8-2021    11:44   14  hr                  3-8-2021 16:12
6-8-2021     9:29   11  hr    15 S  177 W   4-8-2021 00:05
6-8-2021     7:50    8  hr    19 N  180 W   4-8-2021 15:44
6-8-2021     6:40    6  hr    38 S  108 W   4-8-2021 23:04
6-8-2021     6:26    5  hr     4 N  146 W   5-8-2021 03:27
6-8-2021     2:56  2.9  hr    25 N  112 E   5-8-2021 12:14
6-8-2021     5:07  2.5  hr    22 S  104 W   5-8-2021 16:37
6-8-2021     5:34  1.7  hr    29 S   24 E   5-8-2021 21:00
6-8-2021     4:49  1.6  hr    32 N  148 W   5-8-2021 21:00*

The last orbit was re-issued with an epoch almost similar to the previous orbit. This orbit is indicated by an asterisk and my final forecast.

Within current uncertainty windows, no meaningful prediction can be given about the location of the reentry yet. The values nevertheless listed in the tabe for latitude and longitude are nominal values only for the middle of the quoted uncertainty interval (which spans multiple revolutions around the Earth). Given the current uncertainty intervals, they are basically meaningless. Only an hour or so before the actual reentry, the uncertainty interval becomes less than one revolution.

The map below shows the nominal GMAT and last pre-reentry CSpOC TIP positions, plus the trajectory over the uncertainty window [EDIT: see update with final TIP at end of post!!!!]:

 

click map to enlarge

The rocket stage has a dry mass of about 4 tons and is about 4 x 4 meter wide. The diagram below shows the evolution of the orbital altitude of the rocket stage so far, based on CSpOC tracking data. Perigee is the lowest point in it's elliptical orbit around earth, apogee the highest point. Altitudes refer to the equatorial radius of the earth.

 

The last few orbits shows signs of trouble in determining the (quickly evolving) orbit (look at the perigee values for the last four orbits issued). The last available orbit was issued in two versions

 

click diagram to enlarge

 

On July 21, a few hours after launch, I filmed the Proton rocket stage during a pass over Leiden, accompanied by three pieces of debris that were never catalogued by CSpOC:

 

(EDIT: see update below movie!)

UPDATE: 

The final CSpOC TIP is in: 4:46 +- 1m UT (August 6) near 37.8 N 155.7 W, north of Hawaii (this is probably based on a SBIRS detection of the reentry fireball, given the very accurate +- of 1 minute).

This is very close to my last nominal GMAT estimate (4:49 UT near 32 N 148 W)! 

In all honesty: given the uncertainty intervals, that very good match is down to pure luck....

click map to enlarge