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.
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.
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 |
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